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Title: The Medals of Creation, Volumes 1 and 2 - First Lessons in Geology and the Study of Organic Remains
Author: Mantell, Gideon Algernon
Language: English
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Transcriber Note
To preserve cross-references between the volumes, both have been
combined into one. Text emphasis denoted by _Italics_. Whole and
fractional parts of numbers displayed as 123-4/5.
THE
Medals of Creation;
FIRST LESSONS IN GEOLOGY,
AND
THE STUDY OF ORGANIC REMAINS.
VOL. I.
"If we look with wonder upon the great remains of human works, such
as the columns of Palmyra, broken in the midst of the desert; the
temples of Pæstum, beautiful in the decay of twenty centuries; or the
mutilated fragments of Greek sculpture in the Acropolis of Athens,
or in our own museums, as proofs of the genius of artists, and power
and riches of nations now past away; with how much deeper feeling of
admiration must we consider those grand monuments of nature which
mark the revolutions of the Globe; continents broken into islands;
one land produced, another destroyed; the bottom of the ocean become
a fertile soil; whole races of animals extinct, and the bones and
exuviæ of one class covered with the remains of another; and upon the
graves of past generations--the marble or rocky tombs, as it were, of
a former animated world--new generations rising, and order and harmony
established, and a system of life and beauty produced out of chaos and
death; proving the infinite power, wisdom, and goodness of the Great
Cause of all things!"--Sir H. Davy.
[Illustration: _Pl. 1._
_J. Dinkel del. G. Scharf lithog._ _Printed by Hullmandel & Walton_
MEDALS OF CREATION]
THE
Medals of Creation;
FIRST LESSONS IN GEOLOGY,
AND
THE STUDY OF ORGANIC REMAINS.
BY
GIDEON ALGERNON MANTELL, LL.D. F.R.S. V.P.G.S.
PRESIDENT OF THE WEST LONDON MEDICAL SOCIETY, ETC. AUTHOR OF THE
WONDERS OF GEOLOGY, ETC.
[Illustration]
"Voilà! une nouvelle espèce de médailles, beaucoup plus importantes,
et incomparablement plus anciennes, que toutes celles des Grecs et des
Remains!"--Knorr, _Monumens des Catastrophes_.
IN TWO VOLS.--VOL. 1.
CONTAINING
Fossil Vegetables, Zoophytes, Echinoderms, and Molluscs.
SECOND EDITION, ENTIRELY REWRITTEN.
LONDON:
HENRY G. BOHN, YORK STREET, COVENT GARDEN.
MDCCCLIV
LONDON:
R. CLAY, PRINTER, BREAD STREET HILL.
TO
MY SONS,
WALTER MANTELL,
OF WELLINGTON, NEW ZEALAND,
AND
REGINALD NEVILLE MANTELL,
OF KENTUCKY, UNITED STATES,
This Work
MY LAST ATTEMPT TO PROMOTE THE ADVANCEMENT
OF SCIENTIFIC KNOWLEDGE,
IS MOST AFFECTIONATELY INSCRIBED.
G. A. M.
Chester Square, Pimlico,
_Feb. 3, 1853_.
[The above having been penned by the much-lamented author of the
"Medals" some months previous to his decease, it is retained in this
posthumous edition of his favourite work as an appropriate dedication,
dictated by the parental affection of one of the chief promoters of
geological science in England, and addressed to his absent sons, whose
works have already shown them to be enthusiastic labourers in the same
field, both at home and in distant parts of the world.]
PREFATORY NOTE TO THE SECOND EDITION.
The untimely Decease of the lamented Author of the "Medals of Creation"
during the progress of the present edition through the press has
unavoidably delayed its publication.
The First Volume has been wholly rewritten by the Author.
The materials of the Second Volume had been elaborately revised and
much enlarged by Dr. Mantell previously to his Decease. The Editor
has laboured to carry out the intentions of the Author in rendering
this part of the Work as complete a compendium as possible of the
Palæontological history of the Organic Beings of which it treats, and
in adapting it to the requirements of the Geological Student of the
present time.
The various sources from which palæontological and zoological
information has been derived have, for the most part, been adverted to
in the text or in the footnotes. The Editor, however, has especially
to acknowledge the kindness of Mr. J. Morris, F.G.S., in allowing
him to refer to the proof-sheets of the forth-coming edition of his
"Catalogue of British Fossils," and thereby affording him important
assistance in making correct statements of the distribution of the
Fossil Remains of the Crustacea, Insecta, and Vertebrata, in the strata
of the British Islands.
T. Rupert Jones.
PREFACE TO THE FIRST EDITION.
In the first edition of the Wonders of Geology, an intention was
expressed of immediately publishing, as a sequel to those volumes,
"First Lessons," or an Introduction to the Study of Petrifactions, for
persons wholly unacquainted with the nature of Fossil Remains; but the
completion of the contemplated work was unavoidably postponed, from
year to year, by the long and severe indisposition of the Author.
In the meanwhile several works professing the same object have issued
from the press; and an enlarged edition of Sir C. Lyell's "Elements"
has also appeared, in which the elementary principles of physical
Geology are fully illustrated, and numerous figures given of the
characteristic fossils of the several formations, or groups of strata.
But that department of the science which especially treats of Organic
Remains is necessarily considered in a cursory manner; and a work
upon the plan originally contemplated by the Author seems still to be
required, to initiate the young and uninstructed in the study of those
Medals of Creation--those electrotypes of nature--the mineralized
remains of the plants and animals which successively flourished in the
earlier ages of our planet, in periods incalculably remote, and long
antecedent to all human history and tradition.
With this conviction the present volumes are offered, with such
modifications of the original plan as circumstances have rendered
necessary, as a guide for the Student and the Amateur Collector of
fossil remains; for the intelligent Observer who may desire to possess
a general knowledge of the subject, without intending to pursue
Geology as a science; and for the Tourist who may wish, in the course
of his travels, to employ profitably a leisure hour in quest of those
interesting memorials of the ancient physical revolutions of our globe,
which he will find everywhere presented to his observation.
Crescent Lodge, Clapham Common, _May_, 1844.
ADDRESS TO THE READER.
"Some books are to be tasted--others to be swallowed--and some few to
be chewed and digested; that is, some Books are to be read only in
parts--others to be read, but not curiously--and some few to be read
wholly and with diligence and attention."--Lord Bacon's Essays.
Anxious that the "Courteous Reader" should derive from this work all
the information it is designed to impart, the Author presumes to
offer a few words in explanation of the plan upon which it has been
constructed, and some suggestions as to the best means of rendering its
contents most available to the varied tastes and pursuits of different
classes of readers.
In its arrangement, a three-fold object was had in view; namely, in the
first place, to present such an epitome of Palæontology, the science
which treats of the fossil remains of the ancient inhabitants of the
Globe, as shall enable the intelligent Observer to comprehend the
nature of the principal discoveries in modern Geology, and the method
of investigation by which such highly interesting, and unexpected
results, have been obtained..
Secondly, to assist the Collector in his search for Organic
Remains,--directing attention to those objects which possess
the highest interest, and are especially deserving of accurate
examination--instructing him in the art of developing and preserving
the specimens he may discover--and pointing out the means to be
pursued, for ascertaining their nature, and their relation to existing
plants or animals.
Thirdly, to place before the Student a familiar exposition of the
elementary principles of Palæontology, based upon a general knowledge
of the structure of vegetable and animal organization; to excite in his
mind a desire for further information, and prepare him for the perusal
and study of works of a higher order than these unpretending volumes;
and to point out the sources from which the required instruction may be
derived.
Although fully aware of the imperfect manner in which these intentions
are fulfilled, the Author hopes that the indulgence claimed by one of
the most able writers of our times may be extended to him; and that,
"if the design be good upon the whole, the work will not be censured
too severely for those faults, from which, in parts, its very nature
would scarcely allow it to be free."[1]
[1] Sir E. B. Lytton--preface to the second edition of "The Disowned."
With regard to the best means of making use of these volumes, the
advice of the great founder of Inductive Philosophy, on the Study of
Books in general, expressed in the quotation prefixed to this address,
is peculiarly applicable to the different classes of readers for whom
the work is designed.
Thus, "_the Book may be tasted, that is, read only in parts_," by the
intelligent reader, who requires but a general acquaintance with the
subjects it embraces. The perusal of the introductory and concluding
remarks of each chapter, of the general descriptions of fossil
remains, and of the circumstances under which they occur,--omitting the
scientific terms and descriptions,--and a cursory examination of the
illustrations, will probably satisfy his curiosity; and the work may
be transferred to the library for occasional reference, or taken as a
travelling companion and guide to some interesting geological district.
But the Book "_must be swallowed, that is, read, but not curiously_,"
by the reader desirous of forming a collection of organic remains. A
general acquaintance with its contents, and a careful investigation
of the characters of the fossils, and comparison with the figures and
descriptions, will be requisite to enable the amateur collector to
determine the nature of the specimens he may discover.
By the Student the Book "_must be digested, that is, read wholly, and
with diligence and attention_." He should fully comprehend one subject
before he advances to the consideration of another, and should test
the solidity of his knowledge by practical research. He should visit
some of the localities described; collect specimens, and develope
them with his own hands; examine their structure microscopically;
nor rest satisfied until he has determined their general characters,
and ascertained their generic and specific relations. Nor is this an
arduous or irksome task; by a moderate degree of attention, a mind
of average ability may quickly overcome the apparent difficulties,
and will find in the knowledge thus acquired, and in the accession of
mental vigour which such investigations never fail to impart, an ample
reward for any expenditure of time and trouble.
It is, indeed, within the power of every intelligent reader, by
assiduity and perseverance, to attain the high privilege of those who
walk in the midst of wonders, in circumstances where the uninformed and
uninquiring eye can perceive neither novelty nor beauty; and of being
"Even as one,
Who by some secret gift of soul or eye,
In every spot beneath the smiling sun.
_Sees where the Springs of living Waters lie!_"
TABLE OF CONTENTS.
~~~~~~~~
VOL. I.
Dedication, p. v.
Prefatory Note to the Second Edition, vii.
Preface to the First Edition, ix.
Address to the Reader, xi.
Table of Contents, xv.
Description of the Plates, xix.
List of Lignographs in Vol. I., xxxi.
Introduction, 1.
Preliminary Remarks:--On the Plan of the Work and the Arrangement and
Subdivision of the subjects it embraces, 8. Works of Reference, 8.
Explanation of Terms, 11. List of subjects, 12.
PART I.--Stratigraphy of the British Islands, and the Nature of
Fossils, 15.
Chapter I.--On the Nature and Arrangement of the British Strata and
their Fossils, 15.
Chapter II.--Synopsis of the British Strata, 23. Chronological
Arrangement of the British Formations; Modern or Human Epoch;
Post-Pliocene, 23. Tertiary Epochs, 24. Secondary Epochs, 25.
Palæozoic Epochs, 30. Hypogene Rocks, 34. Volcanic Rocks, 35.
Chapter III.--On the Nature of Fossils or Organic Remains, 37.
Incrustations, 38. Silicification, 40. Animal Remains, 43. Hints
for Collecting Fossil Bones, 45.
PART II.--Fossil Botany, 51.
Chapter IV.--Fossil Botany, 51. Fossil Vegetables, 51. On the
investigation of the Fossil Remains of Vegetables, 54. Endogenous
Stems, 56. Exogenous Stems, 56. Structure of Coniferæ, 57.
Botanical principles, 58. Exogens, 59. Endogens, 59. Investigation
of Fossil Stems, 61. Fossil Leaves, 64. On the Microscopical
Examination of Fossil Vegetables, 65. Mode of preparing slices of
Fossil Wood, 66.
Chapter V.--On Peat-wood, Lignite, and Coal, 69. Submerged Forests;
Peat, 70. Lignite, Brown-coal, Cannel-coal, 71. Bovey-coal,
72. Jet, 72. Wealden Coal, 73. Coal, 76. Stratification of a
Coal-field, 80. Origin and Nature of Coal, 82.
Chapter VI.--Fossil Vegetables, 86. Fossil Cryptogamia, 87. Recent
Diatomaceæ, 88. Fossil Diatomaceæ, 93. Fossil Coniferæ, 100. Fossil
Fucoids, 101. Chondrites, 101. Moss-agates and Mocha-stones, 103.
Equisetaceæ, 105. Calamites, 107. Filicites or Fossil Ferns, 109.
Pachypteris, 112. Sphenopteris, 112. Cyclopteris, 114. Neuropteris,
115. Glossopteris, 115. Odontopteris, 116. Anomopteris, 116.
Tœniopteris, 117. Pecopteris, 118. Lonchopteris, 119. Phlebopteris,
120. Clathropteris, 121. Stems of Arborescent Ferns, 122.
Caulopteris, 123. Psarolites, 123. Sigillariæ and Stigmariæ, 125.
Internal Structure of Sigillariæ, 130. Stigmaria, 132. Lepidodendron,
137. Lepidostrobus, 140. Triplosporite, 142. Lycopodites, 143. Halonia
and Knorria, 143. Asterophyllites, 145. Sphenophyllum, 147.
Cardiocarpon, 147. Trigonocarpum, 148. Fossil Cycadaceæ, 150.
Pterophyllum, 152. Zamites, 152. Trunks and Stems of Cycadaceæ, 156.
Mantellia, 157. Clathraria, 159. Endogenites, 163. Fossil Coniferæ,
164. Fossil Coniferous Wood, 167. Palæoxylon, 167. Pence, 168.
Araucarites, 168. Sternbergia, 168. Petrified Forests of
Conifers, 169. Coniferous Wood in Oxford Clay, 172. Coniferous Wood
in Chalk, 173. Tertiary Coniferous Wood, 175. Fossil Foliage and
Fruit of Coniferæ, 175. Araucaria, 175. Pinites, 176. Walchia, 177.
Abietites, 178. Thuites, 180. Voltzia, 180. Taxites, 181. Nœggerathia,
181. Fossil Resins and Amber, 181. Fossil Palms, 183. Fossil
Palm-leaves, 185. Fossil Fruits of Palms, 186. Fossil Fruits from the
Isle of Sheppey, 186. Nipadites, 190. Fossil Fruit of Pandanus, 192.
Wood perforated by Teredines, 193. Fossil Liliaceæ, 194. Fossil
Fresh-water Plants, 195. Fossil Fruits of Chara, 195. Fossil
Nymphaeæ, 197. Fossil Flowers, 197. Fossil Angiosperms, 197. Fossil
Flora of Œningen, 200. Carpolithes, 202. Fossil Dicotyledonous Trees,
203. Dicotyledons of the Cretaceous Epoch, 205. Retrospect of Fossil
Botany, 206. On Collecting British Fossil Vegetables, 211. British
localities of Fossil Vegetables, 213.
PART III.--Fossil Zoology, 216.
Chapter VII.--Fossil Zoophytes; Porifera or Amorphozoa; Polypifera
or Corals; Bryozoa or Molluscan Zoophytes, 218. Fossil Porifera,
219. On the Sponges in Chalk and Flint, 222. Spongites, 223.
Fossil Zoophytes of Faringdon, 226. Scyphia, 227. Cnemidium, 228.
Chenendopora, 228. Tragos, 229. Siphonia, 230. Choanites, 233.
Paramoudra, 236. Clionites, 238. Spicula of Sponges, 238.
Spiniferites, 239. Ventriculites, 242. Polype in Flint, 250. Fossil
Polypifera, 251. Graptolites, 255. Fungia, 256. Anthophyllum, 257.
Turbinolia, 257. Caryophillia, 257. Favosites, 258. Catenipora, 259.
Springopora, 259. Lithostrotion, 260. Cyathophyllum, 260. Astræa,
262. Madrepora, 264. Millepora, 264. Lithodendron, 264. Gorgonia,
265. Fossil Bryozoa, 265. Flustra, 266. Crisia, 269. Retepora,
269. Fenestrella, 270. Petalæpora, 270. Pustulopora, 270.
Homœsolen, 271. Idmonea, 271. Verticillipora, 273. Lunulites, 273.
Geological Distribution of Fossil Zoophytes, 273. On Collecting
Fossil Corals, 276. British localities, 278.
Chapter VIII.--Fossil Stelleridæ; comprising the Crinoidea and
the Asteriadæ, 280. Crinoidea, 281. Pentacrinus, 282. Fossil
Crinoidea, 283. Fossil Stems of Crinoidea, 284. Pulley-stones,
285. Apiocrinus, 288. Bourqueticrinus, 291. Encrinus, 292.
Pentacrinites, 293. Actinocrinus, 295. Cyathocrinus, 295.
Rhodocrinus, 297. Eugeniacrinus, 297. Pentremites, 297. Cystidea,
298. Marsupites, 299. Fossil Asteriadæ, 301. Fossil Ossicula of
Star-Fishes, 303. Ophiura, 304. Goniaster, 306. Asterias, 307.
Geological Distribution of the Crinoidea, 308.
Chapter IX.--Fossil Echinidæ, 311. Cidaritidæ, 314. Cidaris, 316.
Diadema, 318. Echinus, 318. Salenia, 318. Spines of Cidarites,
319. Flint Casts of Cidarites, 320. Cidaritidæ of the Palæozoic
Rocks, 321. Clypeasteridæ, 322. Galerites, 322. Holectypus, 324.
Discoidea, 324. Clypeideæ, 325. Clypeus, 325. Nucleolites, 326.
Spatangidæ, 326. Ananchytes, 327. Micraster, 328. Toxaster, 329.
Holaster, 330. Geological Distribution of Echinites, 330. On
Collecting and Developing Echinodermata, 331.
Chapter X.--Fossil Foraminifera; and Microscopical Examination of
Chalk and Flint, 336. Foraminifera, 339. Classification of the
Foraminifera, 342. Nummulites, 344. Orbitoides, 346. Siderolina,
346. Fusulina, 346. Nodosaria, 347. Cristellaria, 348. Flabellina,
348. Polystomella, 348. Lituola, 348. Spirolina, 349. Globigerina,
350. Nonionina, 350. Rotalia, 351. Rosalina, 351. Textularia,
352. Verneuilina, 352. Strata composed of Foraminifera, 352.
Foraminifera of the Chalk and Flint, 355. Fossil Remains of the
Soft Parts of Foraminifera, 357. Foraminifera-Limestones of
India, 362. Foraminifera-deposit at Charing, 363. Foraminifera of
the Oolite, Lias, &c. 364. Foraminifera-deposits of the United
States, 364. Foraminifera of the Carboniferous Formations, 365.
Foraminifera-Limestone of New Zealand, 366. Tertiary Foraminifera,
366. Foraminifera of the Fens of Lincolnshire and Cambridgeshire,
367. Recent Foraminifera-deposit at Brighton, 368. Geological
Distribution of the Foraminifera, 369. Instructions for the
Microscopical Examination of Chalk, Flint, and other Rocks, 371.
Chapter XI.--Fossil Testaceous Mollusks, or Shells, 374. Mollusca,
374. Acephala, 375. Encephala, 378. Fossil Bivalve Shells, 381.
Shell-Rocks, 382. Fossil Brachiopoda, 388. Terebratula, 389.
Spirifer, 390. Rhynchonella, 391. Pentamerus, 391. Orthis, Leptæna,
and Productus, 392. Calceola, 392. Crania, 392. Orbicula, 392.
Obolus, 392. Lingula, 393. Hippurites, 393. Fossil Shells of the
Lamellibranchiates, 394. Monomyaria, 395. Ostrea, 395. Gryphæa,
396. Spondylus, 398. Plagiostoma, 399. Plicatula, 400. Pecten, 400.
Inoceramus, 401. Avicula, 404. Dimyaria, 404. Venericardia, 405.
Pectunculus, 405. Nucula, 406. Pinna, 406. Mytilus, 407. Modiola,
407. Pholadomya, 408. Pholas, 408. Teredo, 410. Trigonia, 412.
Fossil Fresh-water Bivalves, 413. Unio, 414. Cyclas, 416. Fossil
Pteropoda, 417. Fossil Gasteropoda, 417. Fresh-water Univalves,
421. Paludina, 421. Limnæus, 423. Planorbis, 423. Melanopsis, 424.
Marine Univalves, 424. Fusus, 425. Pleurotoma, 425. Cerithium,
425. Potamides, 425. Rostellaria, 426. Dolium, 426. Trochus,426.
Solarium, 426. Conus, 426. Pleurotomaria, 427. Euomphalus, 429.
Murchisonia, 430. Sphærulites, 430. Molluskite, 432. Geological
Distribution of Bivalve and Univalve Mollusks, 436. On the
Collecting and Arranging Fossil Shells, 441. British Localities of
Fossil Shells, 443.
CONTENTS OF VOL. II.
Description of Frontispiece (Plate II.)
List of Lignographs in Vol. II.
Table of Contents.
PART III.--_continued_.
Chapter XII.--Fossil Cephalopoda, 447.
Chapter XIII.--Fossil Articulata, 503.
Chapter XIV.--Fossil Ichthyology; Sharks, Rays, and other Placoid
Fishes, 562.
Chapter XV.--Fossil Ichthyology; Ganoid, Ctenoid, and Cycloid Fishes,
600.
Chapter XVI.--Fossil Reptiles; Enaliosaurians and Crocodiles, 643.
Chapter XVII.--Fossil Reptiles; Dinosaurians, Lacertians,
Pterodactyles, Turtles, Serpents, and Batrachians, 684.
Chapter XVIII.--Fossil Birds, 759.
Chapter XIX.--Fossil Mammals, 775.
PART IV.--Geological Excursions, 827.
Miscellaneous, 905.
General Index, 909.
DIRECTIONS TO THE BINDER.
Plate I.--Frontispiece to Vol. I.
Plate II. Frontispiece to Vol. II.
Plates III., IV., V., and VI., to follow the Table of Contents, and be
placed opposite the description of each.
Lign. 247, to face page 770.
DESCRIPTION
OF THE
FRONTISPIECE OF VOL. I.
PLATE I.
Fig. 1.--A Fern in Coal-shale, from Leicestershire.
2.--A Crustacean in Limestone, from Solenhofen.
3.--A Fish (_Pycnodus rhombus_) in Limestone; from near
Castel-a-mare.
4.--Half the Lower Jaw of a Hyena, from a fissure in a
sandstone rock, near Maidstone.
5.--An Ammonite, from the Isle of Portland.
DESCRIPTION OF THE VIGNETTE OF VOL. I.
A Group of Fossils, containing
Ammonites Mantellii, from the _Chalk-marl_, Sussex.
Turrilites costatus, from the _Lower Chalk_, Rouen.
Chondrites Bignoriensis, from the _Chalk-marl_, Sussex.
Echinus and Fusus, from _Tertiary strata_, Palermo.
DESCRIPTION OF PLATE II.
_The Frontispiece of Vol. II._
A Fossil Fish of the Salmon tribe, allied to the Smelt; from the Chalk,
near Lewes, in Sussex.
[See Vol. II. pages 626 and 628.]
[Illustration: _Pl. 3._
_J. Dinkel del. G. Scharf lithog._
_Printed by Hullmandel & Walton_]
DESCRIPTION OF PLATE III.
_Incrustations, and Fossil Plants._
Figs. 1, 2, 3.--Twigs of Larch and Hawthorn, coated with tufa, or
travertine, from having been exposed to the dripping of
an incrusting spring; from Russia; see p. 39.
5.--A branch of recent _Chara_, with its fruit, with a thin
pellicle of incrustation. Matlock.
6, 7.--Hazel-nuts, from Belfast Lough: fig. 6 is lined with
crystals of calcareous spar; fig. 7 is filled with a
solid mass of the same mineral; see p. 71.
4, 8.--Impressions of Dicotyledonous Leaves in Gypseous Marlstone,
from Stradella, near Pavia; see p. 201.
9.--Eocene Lacustrine or Fresh-water Limestone, from East Cliff
Bay, Isle of Wight, with stems and seeds of Charge: slightly
magnified; see p. 195.
10.--Encrusted Twigs, from Matlock; the vegetable matter has
perished, and left tubular cavities; see p. 39, and p. 873.
[Illustration: _Pl. 4._
_J. Dinkel del. G. Scharf lithog._
_Printed by Hullmandel & Walton_]
DESCRIPTION OF PLATE IV.
Various species of recent Diatomaceæ, to illustrate the Fossil remains
of this Tribe of Vegetables.
_For detailed descriptions, see pages 87-100._
Figs. 1 to 5.--Various kinds of _Xanthidia_: figs. 2, 3, 4, found in a
pond on Clapham Common, and fig. 1. living in a pond
near Westpoint, United States.
1.--Xanthidium _furcatum_: 1/24 of a line in diameter.
2.-- --------- _hirsutum_: 1/36.
3.-- --------- _aculeatum_: 1/24.
4.-- --------- _fasciculatum_: 1/24.
5.-- -------------------- variety of the above.
2*.--Pyxidicula operculata; Carlsbad, Bohemia: 1/48 of a line in
diameter.
6.--Bacillaria vulgaris. 1/36 of a line in diameter. Pond on
Clapham Common.
7.--Cocconeis scutellum: from the Baltic: 1/24 of a line.
8.--Navicula viridis: 1/6 of a line. Ponds on Clapham Common.
9.--The same; a side view; showing the currents produced in the
water by the animal when in locomotion.
10.--Gallionella lineata: 1/36 of a line. Ponds on Clapham Common.
11.--Gallionella moniliformis: 1/72 of a line.
12.--Synhedra ulna: 1/9 of a line: the point _a_, marks the pedicle
of attachment. Ponds on Clapham and Wandsworth Commons.
13.--Podosphenia gracilis: 1/12 of a line; attached to a thread of
_Calothria_ and having by self-division formed a
radiating cluster. Common in the ditches communicating with
the Thames in Battersea-fields.
14.--Navicula splendida: 1/12 of a line in diameter.
15.--Lateral view of the same.
16.--Eunotia turgida: 1/14 of a line; the empty shell, with
sixty-five ribs, viewed laterally.
17.--A living group of the same: 1/20 of a line: a piece of
_Conferva rivularis_, beset with these animalcules.
The smaller species are _E. Westermanni_.
[All the above organisms were figured and described by Ehrenberg as
animals (_Polygastrica_), and are comprised in his family _Bacillaria_;
they are now, however, regarded as unquestionably vegetable structures,
belonging to the family of Algæ, termed _Diatomaceæ_.]
[Illustration: _Pl. 5._
_J. Dinkel del. G. Scharf lithog._
_Printed by Hullmandel & Walton_]
DESCRIPTION OF PLATE V.
_Illustrative of the Structure of Fossil Vegetables._
Fig. 1.--Polished transverse section of silicified Monocotyledonous Wood,
from Antigua; p. 185.
1_a_.--Magnified 20 times linear.
1_b_.--Magnified 75 times linear.
2_a_.--Transverse section of silicified Coniferous Wood
(_Abies Benstedi_) from the Kentish Rag, near Maidstone
(Iguanodon quarry), × 120 linear; p. 173.
2_b_.--Vertical or longitudinal section of the same, × 250
linear.
3_a_.--Transverse section of calcareous coniferous wood, from
Willingdon, Sussex, × 80 linear; p. 173.
3_b_.--Longitudinal section of the above, × 120 linear.
4.--Slice of a transverse section of a recent Dicotyledonous Stem;
showing, 1st, Pith or medullary column, occupying the centre;
2d, Four bands of woody layers, separated by condensed lines
of elongated tissue in series, and having large regular
openings of vessels, with numerous medullary rays running
continuously from the central pith to the bark; 3d, the bark.
(_From Mr. Witham._)
5.--Slice of a transverse section of a recent gymnospermous
phanerogamic stem (of a Cycas), having a central pith, with
woody layers separated by a condensed line, and consisting of
elongated cellular tissue, arranged in a regular series;
medullary rays and bark. (_From Mr. Witham._)
6.--Bundles of vascular tissue in Stigmaria ficoides, × 12 linear.
See p. 135.
The two strands of vessels that appear as if on the surface (and
are of a looser texture) are part of the vascular tissue of
the stem, and become inflected (that is, bent over), and give
rise to a band of vessels (the darker band seen between the
above), that passes towards the bark or cortical covering.
7.--Portion of a transverse section of one of the bundles of
vascular tissue of _Sigillaria elegans_, × 20 linear.
(From _M. Brongniart._) See p. 131.
The convex portion on the left, and which in the original stem
is situated towards the centre, is composed of the medullary
vascular tissue formed of vessels irregularly disposed.
The longitudinal bundles are the woody fibres arranged in a
radiated circle: the smooth interspaces are medullary rays.
The two distinct roundish spots of vascular tissue on the right
of the ligneous zone occur irregularly on the outside of the
woody circle, and are supposed to be detached bundles of the
ligneous zone extending towards the leaves. See p. 131.
[Illustration: _Pl. 6._
_J. Dinkel del. G. Scharf lithog._
_Printed by Hullmandel & Walton_]
DESCRIPTION OF PLATE VI.
_Illustrative of the Structure of Fossil Teeth._
Fig. 1_a_.--Tooth of _Psammodus porosus_, from the Mountain Limestone.
See p. 587.
1_b_.--Vertical section, a portion × 75 linear.
1_c_.--Transverse section of the same, × 75.
2_a_.--Tooth of _Ptychodus polygurus_, from the Chalk, near
Lewes. See p. 585.
2_b_.--Portion of longitudinal section, × 20.
2_c_.--Portion of transverse section, × 20.
3_b_.--Tooth of the _Labyrinthodon Jægeri_, from the New Red
sandstone near Wirtemberg; half the natural size: the specimen
presented by Dr. Jæger. See p. 742.
3_a_.--A moiety of a transverse polished section, × 20.
3_b_.--Portion of a vertical section near the apex, × 20.
3_c_.--One of the anfractuosities of fig. 3_a_ × ×.
4_a_.--Crown or upper portion of a tooth of a young _Iguanodon_,
from Tilgate Forest. See p. 697.
4_b_.--Portion of a vertical section of the above, × 20.
4_c_.--A small portion of a transverse section of the same, × 20.
5.--Tooth of _Goniopholis_, Tilgate Forest: half the natural size.
See p. 678.
6_a_.--Tooth of a reptile (probably of the _Hylæosaurus_), from
Tilgate Forest; half the natural size. See p. 690.
6_b_.--Portion of a vertical section of the same, × 20.
7_a_.--Tooth of _Megalosaurus_, from Tilgate Forest. See p. 687.
7_b_.--Portion of a vertical section of the same, × 10.
8.--A small portion of a vertical section of a tooth of _Dendrodus_.
See p. 618.
9.--Portion of a transverse section of the base of a tooth of
_Ichthyosaurus_, × 20. See p. 665.
10_a_.--Tooth of _Lepidotus_, Tilgate Forest. See p. 606.
10_b_.--The upper figure is a transverse section, and the lower
a vertical section of the same, × 20.
LIST OF LIGNOGRAPHS IN VOL. I.
============
(_Illustrative of Fossil Botany._)
LIGN. PAGE
1. Sections of Recent Vegetables 55
2. Sections of Fern-Stems 62
3. Nodule of Ironstone, enclosing a Fern Leaf 69
4. Siliceous Frustules of Diatomaceæ, and Spicules of Spongillæ 94
5. Fossil Gallionellæ 96
6. Organic Bodies in Porcelain Earth 97
7. Microphytes from the Tertiary deposits at Richmond, U.S. 98
8. Confervites Woodwardii 101
9. Chondrites Bignoriensis 102
10. Delesserites (Fucoides) Lamourouxii 103
11. Moss and Conferva in transparent quartz 104
12. Equisetum Lyellii 105
13. Equisetites columnaris 106
14. Calamites decoratus 107
15. Calamites in Coal-shale 108
16. Pecopteris Sillimani 110
17. Pachypteris lanceolata 112
18. Sphenopteris elegans 112
19. Sphenopteris nephrocarpa 113
20. Sphenopteris Mantellii 113
21. Cyclopteris trichomanoides 114
22. Neuropteris acuminata 115
23. Glossopteris Phillipsii 116
24. Odontopteris Schlotheimii 116
25. Anomopteris Mougeotii 117
26. Tœniopteris latifolia 118
27. Fig. 1, Pecopteris Murrayana 118
2, Pecopteris lonchitica 118
28. Lonchopteris Mantellii 119
29. Fig. 1, Phlebopteris Phillipsii 120
2, Phlebopteris propinqua 120
30. Clathropteris meniscoides 121
31. Caulopteris macrodiscus 123
32. Base of a Trunk of a Sigillaria, with root 126
33. Sigillariæ, in Coal Shale 128
34. Sigillaria Saullii 129
35. Silicified Stem of Sigillaria elegans 130
36. Stigmaria ficoides 133
37. Transverse section of Stigmaria ficoides 135
38. Erect Stem of a Sigillaria, with Roots 136
39. A Terminal Branch of a Lepidodendron 138
40. Lepidostrobi, the Fruit of Lepidodendra 141
41. Stems of Halonia and Knorria, from the Coal Formation 144
42. Asterophyllites equisetiformis 147
43. Fig. 1, Sphenophyllum Schlotheimii 148
2, Sphenophyllum erosum 148
44. Fossil Fruits, or Seed Vessels 149
45. Foliage and upper part of the Stem of Cycas revoluta (recent) 150
46. Part of a leaf of Pterophyllum comptum 152
47. Part of a leaf of Zamites pectinatus 153
48. Fruit of Zamites Mantellii 154
49. Fossil Fruits of Cycadeous Plants 156
50. Mantellia nidiformis 157
51. Mantellia cylindrica 158
52. Clathraria Lyellii, inner Axis of the Stem of 159
53. Clathraria Lyellii, Stem of 160
54. Clathraria Lyellii, part of Stem of 161
55. Clathraria Lyellii, Petiole of 161
56. Clathraria Lyellii, summit of Stem, with petioles 162
57. Clathraria Lyellii, water-worn Stem of 163
58. Fragment of Coniferous Wood in Flint 174
59. Fig. 1, Part of a Branch of Araucaria peregrina 176
2, Calamites nodosus, with foliage 176
60. Walchia hypnoides 178
61. Abietites Dunkeri 179
62. Thuites Kurrianus 180
63. Nipadites and other Fossil Fruits from the Isle of Sheppey 188
64. Fossil Fruits from the Isle of Sheppey 189
65. Fossil Wood perforated by Teredines 193
66. Fossil Fresh-water Plants 196
67. Fossil Fruits and Flower 198
68. Imprints of Dicotyledonous leaves in Gypseous Marlstone 201
(_lllustrative of Fossil Zoology._)
69. Coral and Spongites 224
70. Fossil Zoophytes 227
71. Fossil Sponge 228
72. Fossil Zoophytes 229
73. Siphoniæ from the Greensand 231
74. Polypothecia dichotoma 232
75. Choanites Königi 234
76. Paramoudra in the Chalk 237
77. A group of Spiniferites in Flint 239
78. Spiniferites Reginaldi 241
79. Spiniferites palmatus 241
80. Flints, the forms of which are derived from Zoophytes 243
81. Ventriculites radiatus 244
82. Portions of Ventriculites 245
83. Ventriculites alcyonoides 248
84. A Coral Polype, in flint 250
85. Graptolites in Wenlock Limestone 255
86. Favosites polymorpha 258
87. Corals from the Dudley Limestone 261
88. Fossil Corals 262
89. Corals from the Chalk and Mountain Limestone 268
90. Stems of Encrinites and Pentacrinites 284
91. Recent Comatula and Fossil Crinoidea 286
92. Fossil Crinoidea 289
93. Apiocrinites 291
94. Actinocrinites and Pentacrinite 294
95. Cyathocrinites planus 296
96. Marsupites Milleri 300
97. Fossil remains of Star-fishes 305
98. Goniaster Mantelli 306
99. Asterias prisca 308
100. Fossil Turban Echinus with its Spines 311
101. Cidarites from the Oolite and Chalk 316
102. Fossil Spines of Cidarites 319
103. Echinital remains in flint 320
104. Echinites from the Chalk 323
105. Holectypus inflatus 324
106. Discoidea castanea 325
107. Micraster cor-anguinum 328
108. Toxaster complanatus 329
109. Foraminifera from the Chalk 342
110. Nummulites, or Nummulina 344
111. Foraminifera from the Chalk 347
112. Spirolinites in flint 349
113. Nonionina Germanica (recent) 350
114. Foraminifera in Chalk and flint 351
115. Chalk-dust, chiefly composed of Foraminifera 355
116. Section of a Rotalia in flint 356
117. Rotalia in flint, with the fossilized body of the animal in
the shell 358
118. Soft Bodies of Foraminifera extracted from the Chalk 359
119. Remains of Foraminifera in chalk and flint 361
120. Fossil Oyster, from the Chalk 374
121. Recent Bivalve Mollusc, showing the several parts of the
shell and the animal 377
122. Turritellæ from Bracklesham 383
123. Shell-Conglomerate 385
124. Shell-Limestone, from the mouth of the Thames 386
125. Terebratula and Rhynchonella 388
126. Terebratula and Spirifer 390
127. Shells and Echinite from the Oolite and Lias 397
128. Spondylus spinosus in Chalk-flint 399
129. Inoceramus Cuvieri of the Chalk 401
130. Flint with fragments of Inoceramus perforated by Clionites 403
131. Unio Valdensis 415
132. Cyclas and Melanopsis 416
133. Fossil Shells of Gasteropoda 418
134. Polished Slab of Purbeck Marble 422
135. Univalves from the Chalk of Touraine 427
136. Univalves from the Mountain Limestone 428
137. Murchisonia bilineata 430
138. Sphærulites from the Chalk 431
139. Coprolites and Molluskite 432
THE
MEDALS OF CREATION.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
INTRODUCTION.
"Geology, in the magnitude and sublimity of the objects of which it
treats, ranks next to Astronomy in the scale of the Sciences."--_Sir J.
F. W. Herschel._
Geology, a term signifying a discourse on the Earth, (from two Greek
words: viz. γἡ, _ge_, the earth; and λὁγος, _logos_, a discourse,) is
the science which treats of the physical structure of the planet on
which we live, and of the nature and causes of the successive changes
which have taken place in the organic and inorganic kingdoms, from
the remotest period to the present time, and is therefore intimately
connected with every department of natural philosophy.
While in common with other scientific pursuits it yields the noblest
and purest pleasures of which the human mind is susceptible, it has
peculiar claims on our attention, since it offers inexhaustible and
varied fields of intellectual research, and its cultivation, beyond
that of any other science, is in a great measure independent of
external circumstances; for it can be followed in whatever condition
of life we maybe placed, and wherever our fortunes may lead us.
The eulogium passed by a distinguished living philosopher on scientific
knowledge in general, is strikingly applicable to geological
investigations. "The highest worldly-prosperity, so far from being
incompatible with them, supplies additional advantages for their
pursuit; they may be alike enjoyed in the intervals of the most
active business, while the calm and dispassionate interest with which
they fill the mind, renders them a most delightful retreat from the
agitations and dissensions of the world, and from the conflict of
passions, prejudices, and interests, in which the man of business finds
himself continually involved."[2]
[2] Sir J. F. W. Herschel, "Discourse on the Study of Natural
Philosophy."
From the present advanced state of geological science, particularly
of that department which it is the more especial object of these
volumes to elucidate, namely Palæontology,[3] or the study of Organic
Remains,--it seems scarcely credible, that but little more than a
century ago it was a matter of serious question with naturalists,
whether the petrified shells imbedded in the rocks and strata were
indeed shells that had been secreted by molluscous animals; or whether
these bodies, together with the teeth, bones, leaves, wood, &c. found
in a fossil state, were not formed by what was then termed the plastic
power of the earth; in like manner as minerals, metals, and crystals.
[3] Palæontology: from παλαιος, _palaios_, ancient--οντα, _onta_,
beings--λὁγος, _logos_, a discourse.
In a "Natural History of England," published towards the end of the
last century, it is gravely observed that at Bethersden in Kent, a
kind of stone is found full of shells, "_which is a proof that shells
and the animals we find in them living, have no necessary connexion_."
Another amusing instance of the ignorance on such subjects which
prevailed at no remote period, occurs in a "History of the County
of Surrey," in which it is stated that in a search for coal near
Guildford the borers broke, and "this was thought by Mr. Peter Lely,
the Astrologer, to have been the work of subterranean spirits, who
wrenched off the augers of the miners, lest their secret haunts should
be invaded."
But in the latter part of the seventeenth century, there were several
eminent men in England who were greatly in advance of the age in
which they lived, and strenuously exerted themselves to discover and
promulgate the true principles of Geology. Among these, Dr. Martin
Lister, physician to Queen Anne, was one of the most distinguished.
This accomplished naturalist, in his great work on shells, which
remains to this day a splendid monument of his labours, and of the
talents and filial affection of his two daughters, by whom all the
plates were engraved, figures and describes many fossil shells as real
animal productions, and carefully compares them with recent species.
He also recognised the distinction of strata by the organic remains
they contain; and to him the honour is due of having first suggested
the construction of geological maps;[4] he was likewise well acquainted
with the position and extent of the Chalk and other strata of the South
of England.[5]
[4] See Notes on the Progress of Geology in England, by W. H. Fitton,
M.D. &c. _Philos. Mag._ vols. i. and ii. for 1832 and 1833.
[5] This celebrated physician and British geologist died in 1712, and
was interred in the old church at Clapham; where a tablet to his memory
is affixed to the outside of the north wall of St. Paul's Chapel.
From the foreign writers, who at an early period had obtained some
correct notions of the structure of our planet, and of the nature of
the revolutions it had undergone, I select the following beautiful
and philosophical illustration of the physical mutations to which the
surface of the earth is perpetually subjected. It is from an Arabic
manuscript of the thirteenth century;[6] the narrative is supposed to
be related by Rhidhz, an allegorical personage.
[6] Quoted by Sir C. Lyell in his "Principles of Geology."
"I passed one day by a very ancient and populous city, and I asked
one of its inhabitants how long it had been founded? 'It is, indeed,
a mighty city,' replied he; 'we know not how long it has existed,
and our ancestors were on this subject as ignorant as ourselves.'
Some centuries afterwards I passed by the same place, but I could
not perceive the slightest vestige of the city; and I demanded of a
peasant, who was gathering herbs upon its former site, how long it
had been destroyed? 'In sooth, a strange question,' replied he, 'the
ground here has never been different from what you now behold it.'
'Was there not,' said I, 'of old a splendid city here?' 'Never,'
answered he, 'so far as we know, and never did our fathers speak to us
of any such.'
"On revisiting the spot, after the lapse of other centuries, I
found the sea in the same place, and on its shores were a party of
fishermen, of whom I asked how long the land had been covered by the
waters? 'Is this a question,' said they, 'for a man like you? this
spot has always been what it is now.'
"I again returned ages afterwards, and the sea had disappeared. I
inquired of a man who stood alone upon the ground, how long ago the
change had taken place, and he gave me the same answer that I had
received before.
"Lastly, on coming back again, after an equal lapse of time, I found
there a flourishing city, more populous and more rich in buildings
than the city I had seen the first time; and when I fain would have
informed myself regarding its origin, the inhabitants answered me,
'Its rise is lost in remote antiquity--we are ignorant how long it
has existed, and our fathers were on this subject no wiser than
ourselves.'"
We may smile at the ignorance of the inhabitants of the fabled cities,
but are we in a condition to give a more satisfactory reply should it
be inquired of us, "What are the physical changes which the country you
inhabit has undergone?"--and yet cautious observation, and patient and
unprejudiced investigation, are alone necessary to enable us to answer
the interrogation.
Dismissing from his mind all preconceived opinions, the student must
be prepared to learn that the earth's surface has been, and still is,
subject to perpetual mutation,--that the sea and land are continually
changing place,--that what is now dry land was once the bottom of the
deep, and that the bed of the present ocean will, in its turn, be
elevated above the water and become land,--that all the solid materials
of the globe have been in a softened, fluid, or gaseous state,--that
the relics of countless myriads of animals and plants are entombed in
the rocks and strata,--and that vast mountain-chains, and extensive
regions, are wholly composed of the petrified remains of beings that
lived and died in periods long antecedent to the creation of the human
race. Astounding as are these propositions, they rest upon evidence
so clear and incontrovertible, that they cannot fail to be admitted
by every intelligent and unprejudiced reader, who will bestow but a
moderate share of attention to the examination of the phenomena, of
which the following pages present a familiar exposition.
I cannot conclude these introductory observations, without adverting
to the incalculable benefits which result from scientific pursuits in
general, and of Geology in particular. An able modern writer has justly
remarked:--"It is fearfully true, that nine-tenths of the immorality
which pervades the better classes of society, originate from the want
of an interesting occupation to fill up the vacant time; and as the
study of the natural sciences is as attractive as it is beneficial, it
must necessarily exert a moral and even religious influence upon the
young and inquiring mind. The youth who is fond of scientific pursuits
will not enter into revelry, for frivolous or vicious excitements will
have no fascination for him. The overflowing cup, the unmeaning or
dishonest game, will not entice him. If any one doubts the beneficial
influence of these studies on the morals and character, I would ask him
to point out the immoral young man who is devotedly attached to any
branch of natural science: I never knew such an one. There may be such
individuals--for religion only can change the heart--but if there be,
they are very rare exceptions; and the loud clamours which are always
raised against the man of science who errs, prove how rarely the study
of the works of the Creator fails to exert an ennobling effect upon a
well-regulated mind. Fortunate, indeed, are the youth of either sex,
who early imbibe a taste for natural knowledge, and whose predilections
are not thwarted by injudicious friends."
And while Geology exerts this hallowing influence on the character, it
possesses the great advantage of presenting subjects adapted to every
capacity; on some of its investigations the highest intellectual powers
and the most profound acquirements in exact science are required; while
many of its problems may be solved by any one who has eyes and will use
them; and innumerable facts illustrative of the ancient condition of
our planet, and of its inhabitants, may be gathered by any diligent and
intelligent observer.
But it is surely unnecessary to dwell on the interest and importance
of a study, which instructs us that every pebble we tread upon bears
the impress of the Almighty's hand, and affords evidence of Creative
wisdom; that every grain of sand, every particle of dust scattered
by the wind, may be composed of the aggregated skeletons of beings,
so minute as to elude our unassisted vision, but which possessed an
organization as marvellous as our own;--a science whose discoveries
have realized the wildest imaginings of the poet,--whose realities
far surpass in grandeur and sublimity the most imposing fictions
of romance;--a science, whose empire is the earth, the ocean, the
atmosphere, the heavens;--whose speculations embrace all elements,
all space, all time;--objects the most minute, objects the most
colossal;--carrying its researches into the smallest atom which
the microscope can render accessible to our visual organs,--and
comprehending all the phenomena in the boundless Universe, which the
powers of the telescope can reveal.
And as no branch of natural philosophy can more strongly impress
the mind with that deep sense of humility and dependence, which
the contemplation of the works of the Eternal is calculated to
inspire, so none can more powerfully encourage our aspirations after
truth and wisdom. Every walk we take offers subjects for profound
meditation,--every pebble that attracts our notice, matter for serious
reflection; and contemplating the incessant dissolution and renovation
which are taking place around us in the organic and inorganic kingdoms
of nature, we are struck with the force and beauty of the exclamation
of the poet--
My heart is awed within me, when I think
Of the great miracle which still goes on
In silence round me--the perpetual work
Of Thy Creation, finished, yet renewed
For ever!
PRELIMINARY REMARKS.
ON THE PLAN OF THE WORK, AND THE ARRANGEMENT AND SUBDIVISION OF THE
SUBJECTS IT EMBRACES.
With the view of economizing space, I would refer the reader to the
following volumes for figures and descriptions of such fossils as are
illustrated therein: by this arrangement I hope to afford the student a
comprehensive view of Palæontology, and yet restrict this work within
the limits which as a manual it would be inconvenient to exceed; at the
same time it will be complete in itself, and afford all the information
required by the amateur collector and general reader.
I. Dr. Buckland's _Bridgewater Treatise_: 2 vols. 8vo.--These volumes
contain numerous excellent figures of organic remains; and as the work
is, or ought to be, found in every good public or private library in
the kingdom, it will be accessible to most of my readers.
II. _The Wonders of Geology, or a Familiar Exposition of Geological
Phenomena_; _sixth_ edition, in two vols, with coloured plates, and
numerous figures; by the Author. Price 18_s._--This work is designed
to afford a general view of Geological phenomena, divested as much as
possible of scientific language: it is illustrated by numerous figures
of organic remains.
III. _Geological Excursions round the Isle of Wight and along the
adjacent Coasts of Hampshire and Dorsetshire._ One volume, richly
illustrated. By the Author. Price 12_s._
IV. _Petrifactions and their Teachings; or a Hand-book to the Gallery
of Organic Remains in the British Museum._ One vol. with many original
figures of the most interesting objects. By the Author.[7] Price 5_s._
[7] The three works above named consist of four volumes uniform with
the present edition of the "Medals of Creation:" this series of six
volumes comprises the popular geological works of the Author.
V. _A Pictorial Atlas of Fossil Remains;_ consisting of Coloured
Illustrations selected from "Parkinson's Organic Remains of a Former
World," and Artis' "Antediluvian Phytology." 1 vol. 4to. with
seventy-four coloured plates, and several lignographs, containing
nearly 900 figures of fossils. By the Author. Price 2_l._ 2_s._
To the above may be added Dana's _Mineralogy_, which treats of the
various mineral substances that enter into the composition of the rocks
and strata in which the fossil remains are imbedded.
A good geological map of Great Britain is indispensable. The small
map published by the Society for the Diffusion of Useful Knowledge,
edited by Sir R. Murchison, price 5_s._, is an excellent compendium;
but Mr. Knipe's large "_Geological Map of the British Isles_" is the
most complete and convenient for the traveller: price 3_l._ 3_s._ By
reference to the map, the geological structure, and the prevailing
fossils of a district, may be ascertained.
The above works are referred to as follows: viz.
_Bd._ Dr. Buckland's Treatise.
_Wond._ The Wonders of Geology.
_Geol. I. of W._ Geology of the Isle of Wight.
_Petrifactions._ Petrifactions and their Teachings.
_Pict. Atlas._ Pictorial Atlas of Organic Remains.
The following works, to which reference will often be made, are thus
denoted:--
_Foss. Flor._ The Fossil Flora of Great Britain, by Dr. Lindley, and
W. Hutton, Esq. 3 vols. 8vo.
_Vég. Foss._ Histoire des Végétans: Fossiles, par M. Adolphe
Brongniart. 1 vol. 4 to.
_Geol. Trans._ Transactions of the Geological Society of London. 5
vols. 4to.; and New Series, in 5 vols.
_Geol. Proc._ Geological Proceedings.
_---- Journ._ ---------- Quarterly Journal.
_Sil. Syst._ The Silurian System, by Sir R. I. Murchison. 2 vols.
4to. with plates and map.
_Org. Rem._ Parkinson's Organic Remains of a Former World. 3 vols.
4to.
_Oss. Foss._ Ossemens Fossiles, par Baron Cuvier. 5 vols. 4to.
5^{me.} edit.
_Min. Conch._ Sowerby's Mineral Conchology. 6 vols. 8vo.
_Odont._ Odontography; a Treatise on the Comparative Anatomy of the
Teeth, by Professor Owen. 2 vols. 8vo.
_Brit. Mam._ British Fossil Mammalia; by the same Author. 1 vol. 8vo.
_Brit. Rep._ Reports on British Fossil Reptiles in the British
Association Transactions for 1839, and 1841; by the same Author.
_Phil. York._ Geology of Yorkshire, by Professor John Phillips. 2
vols. 4to.
_South. D._ Fossils of the South Downs, 1 vol. 4to. 42 plates by the
Author. 1822.
_Geol. S. E._ Geology of the South-east of England. 1 vol. 8vo. by
the same.
_Tilg. For._ Fossils of Tilgate Forest. 1 vol. 4to. 20 plates; by the
same. 1827.
_Poiss. Foss._ Recherches sur les Poissons Fossiles, par M. Agassiz.
4 vols. 4to, and 2 vols, folio.
_Man. Geol._ Manual or Elements of Geology, by Sir C. Lyell. 1 vol.
8vo. Edit. 1852.
The following abbreviations are also employed:--
§ 1. _Relative to the Rocks or Strata._
_Drift._ Alluvial deposits, or Drift.
_Tert._ Tertiary. _Lond. C._ London clay.
_Cret._ Cretaceous formation. _U. Ch._ Upper chalk. _L. Ch._ Lower
chalk.
_Trias._ New Red Sandstone, or Triassic deposits.
_Carb._ Carboniferous or Coal formation.
_Mt. L._ Mountain or Carboniferous limestone.
_Devon._ Devonian or Old Red Sandstone formation.
_Sil. Syst._ Silurian System, or formation.
§ 2. _Relative to Organic Remains._
_nat._ Natural size.
× Magnified in diameter: _e.g._ × 8, magnified eight diameters, &c.
× × Highly magnified; the degree not accurately determined.
_inv._ Invisible to the naked eye.
-- Less than natural: _e.g._ --2/3, reduced to two-thirds the
diameter of the original.
_Lign._ Lignograph or woodcut.
_Explanation of Terms._--Upon the occurrence of a scientific word
apparently requiring explanation, the _meaning_, where practicable,
is for the most part given in a parenthesis; for example, Caulopteris
(_fern-stem_); Phascotherium (_pouch-animal_); carboniferous
(_coal-bearing_); except in the case of arbitrary names, and of those
whose derivation cannot be concisely expressed.[8] With the view of
rendering these volumes more generally useful, English terminology
is in many instances made use of, though involving inelegance of
expression.
[8] Upwards of 300 scientific terms are explained in the Glossary,
"Wonders," vol. ii. p. 915-921.
The work is divided into four parts: the first is an _Introduction to
the Study of Organic Remains_; the second treats of _Fossil Botany_;
the third embraces _Fossil Zoology_; and the fourth, under the head
of _Geological Excursions_, illustrates the principles enunciated in
the course of the work, by practical observations on a few instructive
British localities.
PART I.
1. On the British Strata and their Fossils.
2. Arrangement and Characters of the British Formations.
3. On the Nature of Fossils or Organic Remains.
4. On Mineralized Vegetable Remains, and the mode of
conducting their investigation.
5. On Peat, Lignite, and Coal.
PART II.
FOSSIL BOTANY.
Classification of Fossil Vegetables.
1. On the Fossil Remains of Cryptogamiæ.
2. " " Diatomaceæ.
3. " " Ferns.
4. " " Sigillariæ.
5. " " Lepidodendra.
6. " " Cycadaceæ.
7. " " Coniferæ.
8. " " Palms.
9. " " Angiosperms.
Retrospect.
British Localities of Fossil Plants.
PART III.
FOSSIL ZOOLOGY.
On the Fossil Remains of the Animal Kingdom.
1. Zoophytes; Amorphozoa.
2. " Polypifera.
3. Echinoderms; comprising the
a. Crinoidea, or Lily-shaped animals.
b. Asteriada, or Star-Fishes.
c. Echinida, or Sea-Urchins.
4. Foraminifera.
5. Shell-bearing Mollusca.
6. Articulated animals; comprising
a. Crustaceans.
b. Insects.
7. Fishes.
8. Reptiles.
9. Birds.
10. Mammalia.
11. Man.
Retrospect.
PART IV.
I. Geological Excursions in various parts of England,
illustrative of the method of observing geological
phenomena, and of collecting Fossil Remains.
II. Miscellaneous.
On the prices of Fossils; lists of Dealers, &c.
II. Appendix.
PART I.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
CHAPTER I.
ON THE NATURE AND ARRANGEMENT OF THE BRITISH STRATA, AND THEIR FOSSILS.
"To discover order and intelligence in scenes of apparent wildness and
confusion is the pleasing task of the geological inquirer."--Dr. Paris.
The solid materials of which the earth is composed, from the surface to
the greatest depths within the reach of human observation, consist of
minerals and fossils.
Minerals are inorganic substances formed by natural operations, and are
the product of chemical or electro-chemical action.
Fossils are the durable remains of animals and vegetables which have
been imbedded in the strata by natural causes in remote periods, and
subsequently more or less altered in structure and composition by
mechanical and chemical agencies.
The soft and delicate parts of animal and vegetable organisms rapidly
decompose after death; but the firmer and denser structures, such as
the bones and teeth of the former, and the woody fibre of the latter,
possess considerable durability, and under certain conditions will
resist decay for many years, or even centuries; and when deeply
imbedded in the earth, protected from atmospheric influences, and
subjected to the conservative effects of various mineral solutions,
the most perishable tissues often resist decomposition, and becoming
transformed into stone, may endure for incalculable periods of time.
The calcareous and siliceous cases or frustules of numerous microscopic
plants are so indestructible, and occur in such inconceivable
quantities, that the belief of some eminent naturalists of the last
century, that every grain of flint and lime in certain rocks, may have
been elaborated by the energies of vitality, can no longer be regarded
as an extravagant hypothesis. Some idea may be formed of the large
proportion of the solid materials of the globe that has unquestionably
originated from this source, by a reference to the list of strata
which are wholly, or in great part, composed of animal and vegetable
structures, given in the "Wonders of Geology," p. 888.
There are also immense tracts of country that consist in a great
measure of the remains of plants in the state of anthracite, coal,
lignite, &c.; and districts covered with peat-bogs and subterranean
forests.
Although these relics of animal and vegetable organisms are found in
almost every sedimentary deposit, yet they occur far more abundantly,
and in a better state of preservation, in some strata than in others:
nor are they equally distributed throughout the same bed, but are
heaped together in particular localities, and occur but sparingly,
or are altogether absent, in other layers of the same rock. Neither
are the remains of the same kinds of animals and plants found
indiscriminately in strata of different ages: on the contrary, many
species are restricted to the most ancient, others to the most recent
formations; while some genera range through the entire series of
deposits, and also appear as denizens of the existing seas. Hence
organic remains acquire a high degree of importance, not only from
the intrinsic interest they possess as objects of natural history, but
also for the light they shed on the physical condition of our planet in
the remotest ages, and for the data they afford as to the successive
physical revolutions which the surface of the earth has undergone.
Fossils have been eloquently and appropriately termed Medals
of Creation; for as an accomplished numismatist, even when the
inscription of an ancient and unknown coin is illegible, can from the
half-obliterated effigy, and from the style of art, determine with
precision the people by whom, and the period when, it was struck;
in like manner the geologist can decipher these natural memorials,
interpret the hieroglyphics with which they are inscribed, and from
apparently the most insignificant relics, trace the history of beings
of whom no other records are extant, and ascertain the forms and habits
of unknown types of organization whose races were swept from the face
of the earth, ere the creation of man and the creatures which are his
contemporaries. Well might the illustrious Bergman exclaim, "_Sunt
instar nummorum memorialium, quæ de præteritis globi nostri fatis
testantur, ubi omnia silent monumenta historica_."
To derive from these Medals of Creation all the information they are
capable of affording, regard therefore must be had not only to their
peculiar characters, but also to the geological relations of the
strata in which they are imbedded. Data may be thus obtained by which
the relative age of a formation or group of strata can be determined,
as well as the mode of deposition, and the agency by which it was
effected; whether in the bed of an ocean, or of a lake, or estuary,--by
the action of the sea, or of rivers, or running streams,--by the
effects of icebergs or glaciers,--by slow processes through long
periods of time, or by sudden inundations or deluges,--or by the agency
of volcanoes and earthquakes.
The discovery that particular fossils are confined to certain deposits,
was soon productive of important results, which greatly tended to the
advancement of modern Geology; for although Dr. Lister, more than a
century before, had obtained a glimpse of this law, its principles
were neither understood nor regarded in this country until the late
Dr. William Smith, by his own unaided exertions, proved by numerous
observations on the British strata, its value and applicability for the
identification of a deposit, in districts remote from each other.
This phenomenon did not escape the notice of the distinguished French
philosophers, MM. Cuvier and Brongniart, who in their admirable work,
"_Géographie Minéralogique des Environs de Paris_," enunciated the same
principle:--
"Le moyen que nous avons employé pour reconnoitre au milieu d'un si
grand nombre de lits calcaires, un lit déjà, observé, dans un canton
très-éloigné, est pris de la nature des fossiles renfermés dans chaque
couche; ces fossiles sont toujours généralement les mêmes dans les
couches correspondantes, et présentent d'un système de couche à un
autre système, des différences d'espèces assez notables. C'est un
signe de reconnoissance qui jusqu'à présent ne nous a pas trompés."[9]
[9] Géog. Min. Oss. Foss. tom. ii. p. 266.
Now, though recent discoveries have shown that this rule has many
exceptions, and that its too stringent adoption has been productive of
some erroneous generalizations, yet if employed with due caution it
is fraught with the most interesting results, and is the only certain
basis of our knowledge respecting the appearance, continuance, and
extinction, of the lost races of animals and plants, which were once
denizens of our planet.
[Sidenote: ROCKS AND STRATA.]
In the "Wonders of Geology" will be found a comprehensive sketch of
the composition and arrangement of the several formations or groups
of strata; and a reference to that work will afford the student the
necessary information on this branch of Geology. For the convenience
of the general reader I subjoin a synoptical view of the characters and
relations of the British fossiliferous deposits.
The total thickness of the entire series of rocks within the scope
of human examination, is estimated at from fifteen to twenty miles,
reckoning from the summits of the highest mountains to the greatest
depths hitherto penetrated; and as this vertical section scarcely
amounts to 1/400th of the diameter of the globe, it is familiarly
termed the Earth's crust. The substances of which the sedimentary
strata are composed have been deposited by the action of water, and
subsequently more or less modified in structure and composition by
heat, and by electro-chemical forces. The superficial accumulations of
water-worn detritus, consisting of gravel, boulders, sand, clay, &c.
are termed _Drift_, or _Alluvial_ deposits. When the successive layers
in which the sediments subsided are obvious, the deposits are said to
be _stratified_; when the nature of the materials has been altered by
igneous action or high temperature, but the lines of stratification
are not wholly effaced, the rocks are denominated _metamorphic_
(_transformed_). When all traces of organic remains and of sedimentary
deposition are lost, and the mass is crystalline, and composed of
known products of igneous action, such rocks are named _plutonic_, as
granite, sienite, trap, basalt, porphyry, and the like. Lastly, rocks
resembling the lavas, scoria, and other substances emitted by burning
mountains still in activity, are called _volcanic_.
The sedimentary origin ascribed to ancient crystalline rocks is, of
course, hypothetical, since all evidence of aqueous deposition is
wanting, and the minerals (_mica_, _quartz_, and _felspar_) of which
they are so largely constituted, are not readily soluble in water
under ordinary circumstances. But rocks unquestionably deposited by
water, when exposed to intense heat under great pressure, acquire
a crystalline structure (_Wond._ p. 864); and a series of changes,
from a loose earthy deposit, to compact volcanic lava, may be traced
in numerous instances, so as to leave but little doubt that the
rocks called primitive or primary, _may_ have originally been either
argillaceous, siliceous, or calcareous strata, abounding in organic
remains (_Wond._ p. 873). These crystalline masses have been formed
at successive periods; for granite is found of all ages, occurring
in the most ancient, as well as in comparatively modern epochs. The
difference between the composition and aspect of these rocks, and those
of recent volcanoes, is with much probability ascribed to the fact
that the latter are of sub-aerial origin; that is, were erupted on the
surface, and the gaseous products in consequence escaped; while the
former were ejected at great depths, either beneath the sea, or under
immense accumulations of other deposits, and being thus subjected to
great pressure, the volatile elements were confined, and formed new
combinations: in like manner as chalk when burnt in the open air is
converted into lime, the carbonic acid gas escaping; but when exposed
to the same degree of heat in a closed iron tube, is transformed into
granular marble (_Wond._ p. 104).
From these ancient crystalline rocks generally underlying the
sedimentary deposits, and never appearing as if they had been ejected
from a crater, the term _hypogene_[10] (_nether-formed_) is employed
by Sir C. Lyell to designate the whole class; and they are subdivided
into, 1. _plutonic_, those in which all traces of sedimentary origin
are lost, as granite; and 2. _metamorphic_, those which still manifest
traces of stratification, as mica-schist, &c.
[10] Nether-formed, from ιπο, _hypo_, under; and γἱνομαι, ginomai, to be
formed.
The fossiliferous rocks are, for the convenience of study, separated
into three grand divisions.
1. The Tertiary; comprising the deposits between the Chalk and the
superficial Drift and modern Alluvium.
2. The Secondary; from the _Chalk_ to the _Trias or New Red_, inclusive.
3. The Palæozoic; from the _Permian_ to the _Silurian_; including the
vast series of unfossiliferous slate rocks termed the _Cambrian_, in
which all traces of organic remains are lost.
In the following arrangement the strata are enumerated as if lying
in regular sequence, one beneath the other; but in nature such an
unbroken series has never been observed. A few groups only occur in
a serial order, and these but rarely in their original position. The
beds are for the most part disrupted, and lie in various angles of
inclination; sometimes they are completely retroverted, the newer
strata underlying those upon which they were originally deposited. The
order of succession has been ascertained by careful observation of
the relative superposition of the respective members of the series in
different countries; and from an immense number of facts collected by
able observers in every part of the globe.
This synopsis presents a chronological arrangement of the rocks
according to the present state of geological knowledge, but it must
not be supposed that these rigid distinctions, these hard lines, which
are necessary to facilitate the acquisition of a general idea of the
phenomena attempted to be explained, exist in nature. By whatever
names we designate geological periods, there appear to be no clearly
defined boundaries between them in reference to the whole earth:
such well marked lines may be seen in particular localities, but
daily experience teaches us that there is a blending, and a gradual
and insensible passage, from the lowest to the highest sedimentary
strata, particularly in respect of fossil remains. The terms employed
to designate formations can only be considered as expressing the
predominance of certain characters, to be used provisionally, as a
convenient mode of classifying and generalizing the facts collected,
whilst that knowledge is accumulating which in after times will reveal
the nature and order of succession of the principal events in the
earth's physical history.[11]
[11] "Wonders of Geology," p. 892.
Dr. Buckland's "Bridgewater Treatise" (Vol. II. _frontispiece_)
contains a comprehensive Diagram of the rocks and strata of which the
crust of the earth is composed; it was drawn by the late Mr. Thomas
Webster.
CHAPTER II.
SYNOPSIS OF THE BRITISH STRATA.
"Hard lines are admissible in Science, whose object is not to imitate
Nature, but to interpret her works."--Greenough.
The classification of the stratified rocks is based on three principal
characters; namely, 1, the mineral structure; 2, the order of
superposition; and 3, the nature of the organic remains; the following
synopsis has been drawn up in accordance with these principles.[12]
[12] See "Wonders of Geology," vol. i. pp. 200-207, for a Synoptical
Table of the principal rocks.
CHRONOLOGICAL ARRANGEMENT OF THE BRITISH FORMATIONS.
COMMENCING WITH THE UPPERMOST OR NEWEST DEPOSITS.
Modern or Human Epoch.
Alluvial Deposits: remains of Man and existing species of mammalia.
Post-Pliocene.
Drift; Boulder clay; Till; &c. comprising the superficial irregular
accumulations of transported materials, consisting of gravel, boulders,
sand, clay, &c.
_Observations_.--These beds have been formed by a variety of causes;
by land-floods and inundations, by irruptions of the sea, and by the
agency of glaciers and icebergs. They are the catacombs of the extinct
colossal mammalia--of the mastodon, mammoth, rhinoceros, hippopotamus,
elk, horse, ox, whale, &c. They cannot be definitively separated from
those of the Modern or Human epoch, for the gravel beds near Geneva,
which closely resemble the newest tertiary drift in materials and
position, abound in bones of animals, almost all of which belong to
existing species.[13]
[13] See M. Pictet's "_Palæontologie_."
Tertiary Epochs.
An extensive series, comprising many isolated groups of marine
and lacustrine deposits, containing fossil remains of animals and
vegetables of all classes; the greater number of genera and species in
the most ancient or lowermost beds belong to extinct types.
_Subdivisions_:--
1. The Pliocene[14] (_more new_, or _recent_.[15] _Wond._ p. 221);
strata in which the shells are for the most part of recent
species, having only about ten per cent of extinct forms.
(_Norwich Crag._)
2. The Miocene (_less recent_,[16] _Wond._ p. 221); containing about
20 per cent of recent species of shells. (_Suffolk Crag._)
3. The Eocene (_dawn of recent_,[17] in allusion to the first
appearance of recent species--_Wond._ p. 226); the most ancient
tertiary strata contain but very few existing species of shells;
not more than five per cent. (_London, Hants, and Paris basins._)
[14] In the present state of our knowledge, this arrangement is of great
utility, but it will probably require considerable modification, and
must, perhaps, hereafter be abandoned; for it cannot be doubted, that
strata in which no recent species have yet been found, may yield them
to more accurate and extended observations, and those in which only a
few recent species are associated with a large number of extinct forms,
may have these proportions reversed.
[15] From πλειων, _pleion_, more; and καινος, _kainos_, recent.
[16] From μεἱων, _meion_, less, and recent.
[17] From ἠως, _eos_, the dawn or commencement, and _recent_.
_Obs._--The marine are often associated with fresh-water deposits,
and the general characters of the Tertiary system are alternations of
marine and lacustrine strata. In England the most important Tertiary
deposits are those of the London basin, the Isle of Sheppey, the
south-western coasts of Sussex and Hampshire, the north of the Isle of
Wight, and the eastern coasts of Essex, Norfolk, Suffolk. (_Wond._ p.
226.)
Secondary Epochs.
The Cretaceous or Chalk Formation. (_Wond._ p. 296). A marine
formation, comprising a vast series of beds of limestone, sandstone,
marl, and clay, &c.; characterized by remains of extinct zoophytes,
mollusks, cephalopods, echinoderms, crustaceans, fishes, &c.;
lacertians, crocodilians, chelonians, and other extinct reptiles;
drifted coniferous and dicotyledonous wood and foliage, fuci, &c.
_Subdivisions_:--
1. The _Maestricht beds_. Friable coralline and shelly limestones,
with flints and chert.
2. _Upper Chalk_, with flints } _Craie blanche_ of the French
} geologists.
3. _Lower Chalk_, without flints }
4. _Chalk-marl_ _Craie tufeau._
5. _Firestone_, Malm-rock, Upper } _Glauconie crayeuse._
Greensand, or Glauconite }
6. _Galt_, or Folkstone-marl _Glauconie sableuse._
7. _Shanklin_, or Lower Greensand. { _Formation néocomien_; which
{ is divided into _N. supérieur_,
{ the English upper divisions
{ of the Greensand or Kentish
{ rag; and _N. inférieur_, the
{ lower beds of sand and clay,
{ of the southern shore of the
{ Isle of Wight, at Atherfield.[18]
[18] Another subdivision, with _other_ names (chiefly derived from
French localities), has lately been proposed by M. D'Orbigny; which I
notice with the more regret, since this eminent naturalist formerly
repudiated the censurable practice of many modern systematists,
of changing established names of strata and fossils, without any
just cause. The British geologist will smile to see the Wealden
Formation--so eminently distinguished in England and Germany by its
extent, thickness, and remarkable fauna and flora,--ranked as a
subordinate member of the "_Formation néocomien_," of France.
_Obs._--The Maestricht beds are chiefly composed of fawn-coloured
limestones of friable texture; containing peculiar species of corals,
shells, fishes, reptiles, &c. The _Chalk_ is generally white, but
in some localities is of a deep red, in others of a yellow colour;
nodules, layers, and veins of flint occur in the upper, but are seldom
present in the lower chalk. The _Marl_ is an argillaceous limestone,
which generally prevails beneath the white chalk; it sometimes
contains a large intermixture of green or chlorite sand, and then
is called _Firestone_, or _Glauconite_. The _Galt_ is a stiff, blue
or blackish clay, abounding in shells which frequently retain their
pearly lustre. The _Greensand_ is a triple alternation of sands and
sandstones with clays; and beds of cherty limestone called _Kentish
Rag_.
The Wealden; a formation, whose fluviatile character was first
observed and established by the researches of the author (_Wond._
p. 360). A series of clays, sands, sandstones and limestones, with
layers of lignite, and extensive coal-fields; characterized by the
remains of several peculiar terrestrial reptiles, namely, _Iguanodon_,
_Hylæosaurus_, _Pelorosaurus_, _Megalosaurus_; _Crocodilians_ and
_Chelonians_; _Enaliosaurians_; _Pterodactyles_, &c.; Fishes of
fluviatile and marine genera; Insects of several orders; fresh-water
mollusks and crustaceans; conifers, cycads, ferns, &c.
_Subdivisions_:--
1. _Weald-clay_, with Sussex or Petworth marbles.
2. _Tilgate-grit_, and _Hastings sands_.
3. _Ashburnham clays_, shales, and grey limestones.
4. _Purbeck beds_; argillaceous and calcareous shales, and
fresh-water limestones and marbles. Petrified forest, and layers
of vegetable earth; with Cycads and Conifers.
_Obs._--Clays and limestones, almost wholly composed of fresh-water
snail-shells, and minute crustaceans, generally occupy the uppermost
place in the series in Sussex; sands and sandstones, with shales, and
lignite, prevail in the middle; while in the lowermost, argillaceous
beds, with shelly marbles or limestones, again appear; and, buried
beneath the whole, is a petrified pine-forest, with the trees still
erect, and the vegetable mould undisturbed! The upper clay beds and
marbles form the deep valleys or Wealds of Kent and Sussex, and the
middle series constitutes the Forest-Ridge. The Purbeck strata are
obscurely seen in some of the deepest valleys of eastern Sussex;
they emerge on the Dorsetshire coast, form the Island or Peninsula
whose name they bear, and surmount the northern brow of the Isle of
Portland. On the southern coast of the Isle of Wight, the Wealden
beds emerge from beneath the Greensand strata between Atherfield and
Compton Bay on the western limit, and in Sandown Bay on the eastern;
and their characteristic fossils are continually being washed up on
the sea-shore.
The Jurassic or Oolitic Formation. (_Wond._ pp. 202, and 491). A
marine formation of great extent and thickness, consisting of strata
of limestone and clay, which abound in extinct species and genera of
marine shells, Corals, Insects, Fishes, and terrestrial and marine
Reptiles. Land plants of many peculiar types, and the remains of two
genera of Mammalia.
_Subdivisions_:--
Upper Oolite of Portland, Wilts, Bucks, Berks, &c.
1. _Portland Oolite._ Limestone of an oolitic structure, abounding
in ammonites, trigoniæ, &c. and other marine exuviæ. Green and
ferruginous sands--layers of chert.
2. _Kimmeridge clay._ Blue clay, with septaria, and bands of sandy
concretions--marine shells and other organic remains--_ostrea
deltoidea_. Beds of lignite.
Middle Oolite of Oxford, Bucks, Yorkshire, &c.
1. _Coral oolite_, or Coral rag. Limestone composed of corals, with
shells and echinites.
2. _Oxford clay_; with septaria and numerous fossils. Beds of
calcareous grit, called _Kelloway-rock_ swarming with organic
remains.
Lower Oolite of Gloucestershire, Oxfordshire, and Northamptonshire.
1. _Cornbrash_--a coarse shelly limestone.
2. _Forest marble_; concretions of fissile arenaceous
limestone--coarse shelly oolite--sand, grit, and blue clay.
3. _Great oolite_--calcareous oolitic limestone and freestone;
reptiles, corals, &c., upper beds full of shells.
_Stonesfield slate_;--terrestrial plants, insects, reptiles,
_Mammalia_.
4. _Fullers earth beds_;--marls and clays, with fuller's
earth--sandy limestones and shells.
5. _Inferior oolite_--coarse limestone--conglomerated masses
of terebratulæ and other shells--ferruginous sand, and
concretionary blocks of sandy limestone, and shells.
Lower Oolite, of Brora in Scotland.
1. _Shelly Limestones_--alternation of sandstones, shales, and
ironstone; land-plants.
2. _Ferruginous limestone_, with carbonized wood and shells.
3. _Sandstone and shale; with two beds of coal._
Lower Oolite of the Yorkshire coast.
1. _Cornbrash_--a provincial term for a bluish grey rubbly
limestone, with intervening layers of clay.
2. _Sandstones and clays_, with land-plants, thin beds of coal and
shale--calcareous sandstone and shelly limestone.
3. _Sandstone_--often carbonaceous, with clays; coal-beds, and
ironstone, with remains of vegetables.
4. Limestone; ferruginous and concretionary sands.
_Obs._--The difference observable between the lower beds of the Oolite
in the midland counties, and those of Yorkshire and Scotland, is a
fact of considerable interest. The fluvio-marine accumulations of
vegetable matter in the state of coal, with the remains of land-plants
at Scarborough and Brora, together with the presence of insects,
fresh-water crustaceans, mammalia, and terrestrial plants, in the
Stonesfield slate, attest the existence of neighbouring land, and the
action of rivers and currents.
The Lias. (_Wond._ p. 521) A series of clays, shales, and limestones,
with marine shells, cephalopoda, crinoidea, and fishes in
great abundance; reptiles, (particularly of two extinct genera,
_Plesiosaurus_, and _Ichthyosaurus_,) in immense numbers. Drifted wood
and land plants: coniferæ, cycadesæ &c.
_Subdivisions_:--
1. Upper Lias shale, full of saurian remains, belemnites,
ammonites, &c. intercalated with the lowermost beds of the
Oolite: nodules and beds of limestone.
2. Lias marlstone; calcareous, sandy, and ferruginous strata, very
rich in terebratulæ and other marine shells.
3. Lower Lias clay and shale, abounding in _gryphea incurva_, and
other marine shells; intercalations of sands and clays, with
nodules of limestone.
4. Lias rock; a series of laminated limestones, with clay partings.
Bone-bed, with numerous remains of fishes.
_Obs._--The Lias is the grand depository of those tribes of marine
reptiles, the _Ichthyosauri_ and _Plesiosauri_, whose remarkable
forms, structure, and state of preservation, have excited the
attention even of the most incurious. The collection of these
remains in the British Museum, principally formed by Mr. Hawkins, is
unrivalled.[19]
[19] See "Petrifactions," p. 337-367.
The Trias; or New Red Sandstone Formation,[20] (_Wond._ p. 533).
This group of rocks consists of variegated marls, sandstones, and
conglomerates, frequently of a red colour, with marine shells,
crinoideans, fishes, and reptiles; marine and terrestrial plants. This
series contains extensive deposits of rock-salt, and brine-springs.
[20] Called by some geologists _Poikilitic_ (variegated) group.
This formation comprises the _Trias_, or triple group, _viz._ the
_Keuper_, _Muschelkalk_, and _Upper Bunter Sandstein_, of the German
geologists.
_Subdivisions_:--
1. Variegated red, blue, and white marls, and shales, with gypsum
and beds of rock-salt. (_Marnes irisées_ of the French.)
2. Variegated red and white sandstones.
3. Conglomerates formed of the detritus of the older rocks.
4. Bed mottled sandstone, and marls. (_Grès bigarré_ of the French.)
_Obs._--To this formation belong the principal deposits in
Leicestershire and other midland counties of England. Fossils are
not generally abundant, but some localities yield highly interesting
remains. The shelly limestone of Germany, called Muschelkalk, which
contains the _Lily Encrinite_, &c. does not occur in England. Remains
of Conifers allied to the Yew and Araucaria, are found near Coventry;
and peculiar reptiles (_Labyrinthodons_) near Warwick.
Palæozoic Epochs.
The Permian Formation. (_Wond._ p. 533). The separation of the strata
now termed _Permian_ from the _Triassic_, with which they were formerly
classed, was first proposed by Sir Roderick Murchison, and is based on
the fact that the fossils hitherto discovered are entirely distinct
from any that occur in the Trias and subsequent formations; it is,
therefore, inferred, that after the deposition of the so-called Permian
strata, a complete change took place in the faunas and floras of the
lands and seas, and the Trias is _at present_ regarded as the dawn of a
new system of organic beings.
The strata comprised in this group are variegated blue and red marls
and sandstones, like those of the Triassic; magnesian or dolomitic
limestones; and conglomerates more or less coloured with peroxide of
iron.
_Subdivisions_:--
1. Red and white marls.
2. Yellow magnesian limestones, and dolomitic conglomerates of
Yorkshire and Durham.
3. Marl-slate in thin layers, containing reptiles and fishes. The
Keuper schiefer or copper-schist of Mansfeld.
4. Marls and variegated sandstones, sands, and clays.
_Obs._--This group includes the _Lower Bunter_, _Zechstein_, and
_Rothliegendes_[21] of the German geologists. The _Permian_ comprises
all the deposits that intervene between the Triassic above, and the
Carboniferous below; and it is believed that this formation contains
but one type of animal and vegetable life.
[21] Signifying _Red-dead-layer_; it is a German mining term denoting
that the copper of the upper bed has died out; this layer not being
metalliferous.
The Carboniferous, or Coal Formation. (_Wond._ pp. 660-748).
Sandstones, grits, shales, layers of ironstone, and clay, with immense
beds of coal; fresh-water limestones sparingly; marine limestones
abundantly.
_Subdivisions_:--
1. _The Coal Measures._--Sandstones, shales, and grits, with
numerous beds and seams of Coal; ironstone nodules. Land
plants in profusion. Intercalations of bands of limestone with
fresh-water bivalves and crustaceans in some districts; and with
marine shells in others.
2. _Millstone Grit._--Sandstones, shales, and quartzose
conglomerates and grit, (_provincially_, Millstone-grit): with
shales and thin seams of coal, and plants of the coal-measures
in some localities. The conglomerates and grits have evidently
resulted from the destruction of granitic rocks.
3. _Carboniferous_, or _Mountain Limestone_.--A series, nearly
1,000 feet in thickness, of limestones and flagstones, abounding
in crinoideans, corals, and marine shells and crustaceans;
with layers and nodules of chert. Ores of lead, zinc, copper,
barytes; fluor spar, &c. Limestones, with innumerable shells
of the genera Productus, Spirifer, Goniatites, Orthocera,
Bellerophon, &c. Several varieties of black, bluish grey, and
variegated marbles. Coal occurs in the mountain limestone of
some parts of Russia.
_Obs._--The strata comprised in the carboniferous (coal-hearing)
system, consist of sandstones more or less felspathic, and of
dark bituminous shales with innumerable ferns, and other vascular
cryptogamiæ, and coniferæ, &c. The uppermost group is composed of
numerous alternations of coal, clay, shale, ironstone, and sandstone;
the middle, of sandstones, shales, clays, and quartzose conglomerates,
generally of a dull red colour; and the lowermost, of crystalline
limestones with occasional layers of chert, abounding in marine
shells, corals, crinoidea, and other exuviæ. These lower limestones
are the principal repositories of the lead ores of Derbyshire.
The Devonian or Old Red Formation. (_Wond._ pp. 204 and 751).
Conglomerates, quartzose grits, sandstones, marls, and limestones;
the prevailing colour is a dull red. Shells, corals, and ganoid
fishes, of a very peculiar type. Reptiles, (Telerpeton; _Batrachians?_
_Chelonians?_); the most ancient reptilian remains hitherto discovered.
_Ferns_, _Lepidodendrons_, and other trees of the carboniferous flora;
fluviatile plants with batrachian ova(?).
_Subdivisions_:--
1. Sandstone, quartzose conglomerates, and shale, with but few
fossils.
2. Flagstones, marls, and concretionary limestones; provincially
termed _corn-stones_; laminated reddish and greenish micaceous
sandstones (_prov. tilestones_). Peculiar genera of fish;
orthocerata, and many species of marine shells.
_Obs._--The term Devonian, by which the series of strata comprehended
in this formation is now generally distinguished by geologists, was
first proposed by Sir R. Murchison, as being more precise than the
name formerly applied to this group. In Scotland, where the formation
is of vast extent, it was first characterized by its peculiar ganoid
fishes (Pterichthys, Coccosteus, Cephalaspis), and will probably
always there retain the original name of Old Red.[22] In Devonshire
it is marked by the presence of shells of a character intermediate
between those of the Silurian and Carboniferous systems.
The sandstones are in various states of induration, and when slaty,
are employed for roofing. The red colour predominates in the marls,
and is derived from peroxide of iron. The formation of these rocks
has manifestly resulted from the waste of ancient slate rocks, the
detritus of which is cemented together into coarse conglomerates. In
South Devonshire (at Torquay, Babbicombe, &c.), beautiful coralline
marbles occur in this formation.
[22] See the charming volume of Mr. Hugh Miller, entitled "The Old Red
Sandstone, or New Walks in an Old Field."
The Silurian System. (_Wond._ p. 765). Marine limestones, sandstones,
shales, and calcareous flagstones, characterized by peculiar types
of corals, crinoideans, mollusks, and crustaceans, constitute this
important and extensive system of rocks; the _Grauwacké_, or Transition
series of the earlier geologists.
_Subdivisions_:--
UPPER SILURIAN.
1. _Ludlow rocks_;--slightly micaceous grey-coloured sandstones.
Blue and grey argillaceous limestones. Dark-coloured shales and
flagstones, with concretions of earthy limestone, containing
marine shells, Orthocerata, Spirifers, and Trilobites. _Fishes._
2. _Wenlock_, or _Dudley limestone_;--sub-crystalline blue and grey
limestone, abounding in Trilobites, Crinoidea, Polyparia,
Spirifers, Orthocerata, &c.
3. _Wenlock shale_;--dark grey argillaceous shale, with nodules of
sandstone.
LOWER SILURIAN.
1. _Caradoc sandstone_;--shelly limestones, and finely laminated,
slightly micaceous, greenish sandstones. Corals, Shells,
Trilobites.
2. _Llandeilo flags and limestones._ Freestone, conglomerates,
grits, and limestones. Dark-coloured flags. Beds of schist with
abundance of Trilobites and shells. The lowermost beds are full
of small bivalves, termed _Lingulæ._
_Obs._--The _Silurian System_, (so named by Sir R. Murchison, from
the _Silures_, the ancient Britons who inhabited those parts of our
island in which the geological relations of these strata were first
recognised by him,) occupies the border counties of England and
Wales, and spreads over a vast area of both North and South Wales,
intervening between the Carboniferous series and the Cambrian or
ancient slate-rocks of that country.[23] The strata are entirely of
marine origin, and many of the beds (as the well-known Dudley or
Wenlock limestone) are composed of shells, corals, crinoideans, and
remains of that remarkable family of crustaceans termed Trilobites,
cemented together by carbonate of lime. A few remains of Fishes occur:
Reptiles are unknown. No vegetable relics, excepting _Fuci_, have been
found in Britain below the _Devonian_ or _Old Red formation_.[24]
[23] "The Silurian System, founded on Geological Researches in the
Border Counties of England and Wales." In two parts, royal 4to., with
map, sections, &c., by Sir R. I. Murchison, G.C. St.S. &c. In studying
the beautiful map which accompanies the work, it must be borne in
mind that ten years have elapsed since Sir R. Murchison abrogated
the boundary line that separates the Cambrian and Silurian rocks
in this chart, from the conviction that those deposits constitute
but one natural system (see _Wond._ p. 80.3). For an account of the
Silurian rocks of other countries, see "Geology of Russia," by the same
Author. A summary of the characters of the Silurian System, by Sir R.
Murchison, is given in _Geolog. Journal_, vol. viii. pp. 173-183.
[24] "The Silurian System" contains excellent figures of all the organic
remains known at the period of its publication.
The Cambrian Formation. This term is applied to a largely developed
series of unfossiliferous slate-rocks and conglomerates, many thousand
yards in thickness.
_Obs._--Certain beds of dark-coloured schists containing a few
corals, fuci, and shells, are referred to the uppermost part of this
formation by some eminent geologists, but it is more consonant to the
established system of classification to regard these fossiliferous
beds as the lowermost of the Silurian rocks. The fineness of grain,
general aspect, hardness, and texture of these strata, are well
known, from the general employment of slate for economical purposes.
These rocks extend over a great part of Cumberland, Westmoreland, and
Lancashire, reaching to elevations of 3,000 feet, and giving rise to
the grand scenery of the Lakes, and of North Wales.
Hypogene Rocks. (_Wond._ p. 806.)
_Non-fossiliferous._
Metamorphic (_transformed_) or stratified crystalline rocks.
_Subdivisions._--
1. _Mica-schist System._ (_Wond._ p. 843.) Probably sedimentary
rocks altered by high temperature. Mica-slate, Quartz-rock,
Crystalline limestone, Hornblende schist, &c.
2. _Gneiss System._ Layers of Gneiss, Sienite and Quartz-rock,
alternating with Clay-slate, Mica-schist, &c.
Plutonic Rocks; unstratified crystalline masses.
_Granitic System._ (_Wond._ p. 844.) Granite--a rock composed of mica,
quartz, and felspar; Porphyry; Serpentine; Trap. These rocks occur in
amorphous or shapeless masses, and in dykes and veins.
_Obs._--No fossils have been detected in these rocks: but the intense
igneous action which the masses appear to have undergone, may have
obliterated all evidence of animal and vegetable structures, should
any have been present, as well as the lines of stratification. By
the aid of the microscope, we may yet perhaps solve the mystery
which shrouds the origin of these rocks, and the student may take
up the investigation with the certainty of obtaining much valuable
information, even should the search for organic structures prove
abortive. It is not, however, improbable that the siliceous frustules
of diatomaceæ may have escaped destruction, and remain to reward the
researches of some skillful and patient observer.
Volcanic Rocks. (_Wond._ p. 815.)
The products of subterranean fire or heat, erupted from profound depths
through fissures in the Earth's crust, whether in ancient or modern
times.
_Subdivisions._--
1. _Trap, Basalt, Toadstone, Volcanic-tuff_; the erupted materials
of ancient extinct volcanoes.
2. _Lavas, Scoriæ, Pumice, Ashes_; ejected by modern volcanoes.
_Obs._--These igneous products are of all ages, and they traverse
alike the hypogene rocks and the older and newer sedimentary deposits.
Their characters, and the effects they have produced, are considered
in the work to which reference is made.
* * * * *
By a reference to the geological map of England (_Wond._ pl. i.
vol. i.), it will be seen, that the several formations appear on
the surface in a somewhat chronological order, as we pass from the
eastern or south-eastern part of the Island to the west or north-west.
Thus the principal Tertiary deposits are situated in the eastern
and south-eastern parts; and proceeding towards the north-west, we
traverse successively the _Secondary_--the _Chalk_, _Oolite_, _Lias_
and _Trias_; then the _Palæozoic_--_Permian_, _Carboniferous_,
and _Devonian_; next the _Silurian_ and _Cambrian_; and at length
_metamorphic_ and _primary_ rocks appear. It is this distribution
of the strata of the respective formations that has determined
the characters of the physical geography of England. The Alpine or
mountainous districts, which extend north and south along the western
portion of England and Wales, from Cornwall to Cumberland, are formed
by the elevated masses of the Silurian, Cambrian, and Metamorphic
rocks. These are succeeded by a band of the Carboniferous and Triassic
deposits, with a few intrusions of metamorphic and plutonic rocks, that
stretches from the coast of Devonshire, through the midland counties,
by Leicestershire and Derbyshire, to Newcastle. On the south-east
of this tract, the Oolite and Cretaceous formations, chiefly made
up of argillaceous and calcareous strata, constitute a diversified
agricultural district, extending from the southern shores of Hants and
Dorset to the coast of Yorkshire. The Wealden occupies the country
lying between the Chalk Downs of Sussex, Hants, Surrey, and Kent. The
Tertiary deposits lie in basins or depressions of the upper cretaceous
rocks in the south-eastern and eastern maritime districts, and on an
extensive area of these beds stands the metropolis of England; lastly,
irregular accumulations of Drift, containing mammalian remains in some
localities, are spread over the surface of the ancient formations, and
form the immediate subsoil of the most fertile regions.
CHAPTER III.
ON THE NATURE OF FOSSILS, OR ORGANIC REMAINS.
Fossils; Petrifactions.--It is very generally the case, that persons
who are not conversant with the nature of organic remains, suppose
that all fossils are petrifactions; and unless a specimen has the
aspect and hardness of stone, they regard it as of modern origin, and
devoid of interest. Hence they are surprised to find among the choicest
treasures in the cabinet of the geologist, shells and corals as perfect
in form, as if recently collected from the sea-shore; bones as little
changed, as if they had been interred but for a short period; and
teeth possessing their sharp edges and enamel unimpaired. In my early
researches I fell into this error, and threw away many beautiful shells
that were associated with casts of ammonites in the marl at Hamsey,
supposing, from their perfect state, that they had been accidentally
imbedded, and were not genuine fossils. But the state of preservation,
and the degree of change which an organic body has undergone in the
mineral kingdom, have no necessary relation to its antiquity. The
shells in some of the ancient secondary strata are frequently as little
changed as those in modern tertiary deposits. I have collected from the
lowermost clays of the Wealden, fresh-water shells with traces of the
epidermis, and the ligament by which the valves were held together,
perfect; and bones of reptiles from the strata of Tilgate Forest, as
light and porous as those of the bears and hyenas, from the Caverns of
Germany. On the other hand, fossil remains from the newest tertiary
formations are often completely petrified, that is, permeated by, or
transmuted into, stone.
The words _fossil_ and _petrifaction_ are so commonly used as
synonymous terms, even by educated persons, that it is necessary to
define the sense in which they are employed in these volumes.
_Fossils_ are the durable parts of animal and vegetable structures
imbedded in rocks and strata by natural causes at a remote period; thus
wood in a state of lignite, bog-wood, and coal, or of siliceous or
calcareous stone, is _fossil wood_; and bones or shells, whether in an
earthy and decaying state, or permeated by calc-spar, flint, or iron,
and converted into a hard mineral substance, are alike _fossil bones_
or _shells_.
_Petrifactions_ are the remains of animals and vegetables in which
the original structure is converted into stone, or, in other words,
is _petrified_; such are the silicified stems of trees from Antigua,
and Germany, and the calcified bones and shells in the Oolitic and
Wealden limestones. Such petrifactions may be correctly termed fossil
plants, bones, or shells; but similar organic remains, though of equal
antiquity, which have not undergone such changes, are not petrifactions
in the proper meaning of that term.
The process by which petrifaction is effected is still involved in
obscurity; mineral solutions have permeated the original tissues,
and the organic molecules have been replaced by mineral molecules,
but how this transmutation is produced is not understood. Mr. Dana's
observations and Mr. Jeffery's experiments have, however, thrown much
light on the process of silicification.[25]
[25] See _Wond._ p. 100.
_Incrustations._--Another prevalent error is that of considering
Incrustations to be fossils or petrifactions; a mistake which is
sanctioned by the custom of calling waters that are charged with
calcareous earth (_lime_), and deposit it in considerable quantity,
petrifying springs; as those of Matlock, and other places in
Derbyshire. (_Wond._ p. 76.) But incrustations are not petrifactions;
stems and branches of trees, skulls, bones, shells, &c., are simply
invested with a calcareous coating or crust, which is generally porous
and friable, but often crystalline and compact. The inclosed bodies
are not permeated by the stony matter; if the mass be broken, or
the incrustation removed, we find the twig, or stem, either dry and
shrivelled, as in the specimens, figs. 2, 3, 4, Plate III.; or tubular
cavities are left by the decay and removal of the vegetable structure,
as in fig. 10, Plate III.
But although incrustations be not petrifactions, natural specimens,
(not the so-called petrified nests and twigs, in which the bad taste of
the guardians of the Derbyshire springs is embodied, and dispersed all
over England,) are objects of considerable interest, as illustrative
of a process, by which important changes are effected in the mineral
kingdom. Thus springs as clear and sparkling as poet ever feigned or
sung, may transform beds of loose sand and gravel into rock, and porous
stone into solid marble, and cover extensive tracts of country with
layers of concretionary and crystalline limestone. This process is
effected in the following manner. Most fresh water holds in solution a
certain proportion of carbonate of lime; and changes of temperature, as
well as other causes, will occasion this calcareous earth to be in part
or wholly precipitated. The _fur_, as it is called, that lines a kettle
or boiler which has been long in use, affords a familiar illustration
of this fact. At the temperature of 60° lime is soluble in 700 times
its weight of water; and if to the solution a small portion of carbonic
acid be added, a carbonate of lime is formed, which is thrown down
in an insoluble state. But if the carbonic acid be in such quantity
as to supersaturate the lime, it is again rendered soluble in water:
it is thus that carbonate of lime, held in solution by an excess of
carbonic acid, not in actual combination with the lime, but contained
in the water, and acting as a menstruum, is commonly found in all
waters. An absorption of carbonic acid, or a loss of that portion which
exists in excess, will therefore occasion the lime to be set free, and
precipitated on the foreign bodies in the water, as stones, twigs,
leaves, &c.
The substance thus deposited is termed _tufa_, or travertine;[26] and
in some parts of Italy, and of our own Island, it constitutes beds of
stone of great extent, in which bones, shells, and the impressions of
leaves and stems, are preserved. The stalactites and stalagmites of
caverns have a similar origin; many of these caves are of incalculable
antiquity, and beneath their stalagmitic floors, the bones and teeth of
extinct carnivorous animals are found in vast quantities.
[26] _Travertine_, so called from the river _Tibur_, whose waters are
loaded with calcareous earth--_Tiburtina_, Ital. _travertina_.
Silicification, or petrifaction by Silex or Flint.--Silex, or the earth
of flint, is held in solution in large proportions, in certain thermal
or boiling springs, which, on cooling, deposit the siliceous matter
(in the same manner as the travertine is precipitated from incrusting
streams) on foreign substances, and produce exquisite chalcedonic
infiltrations of mosses, &c. But this operation is now only known to
be in activity in the immediate neighbourhood of foci of volcanic
action, as in the celebrated Geysers of Iceland (_Wond._ p. 95), and
the boiling springs of the volcano of Tongariro, in New Zealand (98).
We have everywhere evidence that in former periods, the petrifaction,
as well as the incrustation of organic bodies by silex, was carried on
to an immense extent; and, doubtless, far beneath the surface, the same
operation is at the present moment in constant progress, and effecting
as important changes in the consolidation of loose materials, as in the
earlier geological epochs.
The various states in which silex occurs have depended on its fluidity;
in quartz crystals the solution appears to have been complete; in agate
and chalcedony it was in a gelatinous state, assuming a spheroidal or
orbicular disposition, according to the motion given to its particles.
Its condition appears also to have been modified by the influence
of organic matter. In some polished slices of siliceous nodules the
transition from flint to agate, chalcedony, and crystallized quartz, is
beautifully shown. The curious fact, that the cavities of echinites in
chalk are almost invariably filled with flint, while their crustaceous
cases are changed into calc-spar, is probably, in many instances, to
be attributed to the animal matter having undergone silicification;
for the soft gelatinous parts are those which appear to have been most
susceptible of this transmutation. In some specimens, the oyster is
changed into flint, while the shell is converted into crystallized
carbonate of lime. In a Trigonia from Tisbury, formerly in the cabinet
of the late Miss Benett, of Norton House, near Warminster, the body
of the mollusk was completely metamorphosed into a pure chalcedony,
the branchiæ or gills being as clearly defined as when the animal was
recent. In specimens of wood from Australia (presented to the British
Museum by Sir Thomas Mitchell), which are thoroughly permeated by
silex, there are on the external surface some spots of chalcedony that
have apparently originated from the exudation of the liquid silex from
the interior in viscid globules filled with air, which burst, and then
collapsed, and became solidified in their present form.
In silicified wood the permeation of the vegetable tissues by the
mineral matter, appears to have been effected by solutions of silex of
a high temperature. In some examples the mineralization is simply a
replacement: the original substance has been removed atom by atom, and
the silex substituted in its place.
One of the most eminent naturalists and chemists of the United States,
Mr. Dana,[27] suggests that the reason why silica is so common a
material in the constitution of fossil wood and shells, as well as in
pseudo-morphic crystals,[28] is the ready solution of silex in water
at a high temperature (a fact affirmed by Bergman[29]) under great
pressure, whenever an alkali is present, as is seen at the present
time in many volcanic regions, and its deposition again when the water
cools. A mere heated aqueous solution of silica, under high pressure,
is sufficient to explain the phenomenon of the silicification of
organic structures. Mr. Dana states that a crystal of calc-spar in
such a fluid being exposed to solution, from the action of the heated
water alone, the silica deposits itself gradually on a reduction
of temperature, and takes the place of the lime, atom by atom, as
soon as set free. Every silicified fossil is an example of this
pseudo-morphism; but there seems to be no union of the silica with the
lime, for silicate of lime is of rare occurrence.[30]
[27] American Journal of Science for January 1845.
[28] Pseudo-morphic crystals are crystals moulded in the cavities
left by other crystals which they have replaced. See Dr. Blum on
Pseudo-morphous minerals.
[29] Bergman first determined the solubility of silex in simple water,
aided by heat, and demonstrated its existence in the Geysers and other
boiling springs of Iceland.--_Parkinson, Org. Rem._ vol. i. p. 324.
[30] See my "Notes on a Microscopical Examination of Chalk and Flint,"
Annals of Natural History, August 1845.
* * * * *
I proceed to consider the various states in which the remains of
animals and plants are preserved in the mineral kingdom, and shall
occasionally offer suggestions for collecting and preparing specimens;
but particular instructions on this head will be given in the sequel,
when the different kinds of fossils are respectively considered.
[Sidenote: FOSSIL ANIMAL REMAINS.]
Animal Remains.--Of the higher orders of animals, the more durable
portions of the skeleton, as the bones and teeth, are almost the
only parts that occur in a fossil state; except in some remarkable
instances, in which entire carcasses of extinct species of Elephant,
and of Rhinoceros, have been found imbedded in solid ice, and frozen
gravel. (_Wond._ p. 152.) The countries of arctic regions are now the
only localities in which such phenomena are likely to be met with;
it appears, however, that in some remote period, the bodies of large
mammalia were transported by icebergs into temperate regions, where
the ice melted, and the animals either sunk to the bottom of the sea,
or were drifted into estuaries, or stranded on the shore: the soft
parts then decomposed, and the skeletons and detached bones were left
imbedded in the silt, sand, or shingle.
In this manner alone can be explained the occurrence of bones and teeth
of the mammoth, rhinoceros, hippopotamus, &c. so common in the alluvial
or drifted deposits of this country; for these relics, though extremely
friable, and buried in shingle, boulders, and other transported
materials, are not water-worn, but in numerous instances remain as
sharp and perfect as when recent. In the ancient shingle of Brighton
cliffs (_Wond._ p. 114), I have found bones and teeth of horse, deer,
ox, whale, &c. impacted with quartz and granite pebbles and boulders;
the bones, though crumbling to pieces if not very carefully removed,
being entire, and the whole mass held together by calcareous spar,
deposited by water that had, during the lapse of ages, percolated
through the chalk-rubble above.
Fossil bones are found in four different states: 1. With their animal
matter, as in the bones of the Mastodons from Big-bone Lick, Kentucky.
2. With the animal matter removed. 3. With the earthy matter partly
removed, 4. With the animal matter carbonized, or converted into
bitumen; this change is common in the blue Lias clay; the bones retain
their usual quantity of phosphate of lime, but the animal matter is
converted into carbon. This alteration appears to have taken place
unconnected with a high temperature, and to have been a spontaneous
change in a moist situation, to which air had no access.[31]
[31] Mr. Smee, London Med. Gazette, November 1840.
Another, and very remarkable condition, is that in which the phosphate
of lime has been removed by the infiltration of water charged with
sulphuric or carbonic acid, and the gelatin converted into leather
by tannin; as is the case with bones and teeth of deer, horses, &c.
obtained from a submerged forest of oak, larch, &c. near Ferry-bridge,
in Yorkshire; of which there are many instructive specimens in the York
Museum.[32]
[32] Communicated by Professor John Phillips.
The cancellated structure (that is, the little cells or pores) of
the long-bones of mammalia, found in caverns in England and Germany,
and in the breccia of Gibraltar, and the conglomerates of Ava and
the Sub-Himalaya mountains, &c., are often filled with crystallized
carbonate of lime. In the Wealden deposits the osseous carapaces and
plastrons of Turtles, and the bones and teeth of Crocodiles, Lizards,
&c., are almost without exception heavy, and of various shades of brown
or umber, from the infiltration of solutions of carbonates and oxides
of iron.
In some instances, bones of a jet black are imbedded in the white
calciferous grit; the phosphoric acid in the original organism having
combined with iron and produced a deep blue or black phosphate of that
mineral, and left the surrounding stone uncoloured.
Petrifaction by the infiltration of calcareous solutions is equally
common; and the medullary cavities of the bones are frequently lined
or filled with white calc-spar; brilliant pyrites also enters into the
composition of these fossils, frosting over with a golden metallic
deposit the cavities and fissures.
[Sidenote: FOSSIL BONES.]
The permeation of the teeth by mineral matter, produces beautiful
examples of the tissues of those organs; the dentine is often stained
throughout with a rich sienna tint, and sections viewed under the
microscope by transmitted light, reveal the character and distribution
of the calcigerous tubes more clearly even than in recent specimens.
It is extremely rare that osseous structures are found petrified by
flint; among the many thousands of bones which I have extracted from
the rocks, or have seen in collections, I know but of one instance of
a silicified vertebra, that of a Mosasaurus, from a chalk-pit near
Brighton; and a few bones and scales of fishes. But notwithstanding the
weight and apparent solidity imparted by these modes of mineralization,
the substance is generally rendered extremely brittle, so that the
development of the bones from the stone in which they are imbedded,
and the removal of the hard ferrugino-calcareous crust investing them,
is no easy task, but requires much tact, experience, and patience, to
execute successfully.
Hints for collecting fossil bones.--The light, friable, porous bones,
require great care in their removal from the deposit in which they
are imbedded, whether it be clay, consolidated shingle, or limestone;
if of considerable size, they will almost invariably break to pieces,
and many examples will not admit of repair. It is therefore always
desirable, before attempting to extract a large bone, to make a sketch
of it; its form will thus be known, should it be destroyed; and if it
crack into fragments that will admit of reunion, the drawing will be a
valuable guide for the replacement of the separated parts. If only a
few pieces remain, those which show any portion of the terminations,
or joints, should be preserved, as they afford the most precise and
important characters. The faithful record even of an imperfect and
unknown fossil is not without value; and as the antiquary carefully
preserves shreds of ancient manuscripts, in the hope that other
documents may one day come to light, and enable him to interpret these
now unintelligible records; so the geologist should treasure up every
fragment of an undetermined organic remain, for the time may arrive, as
I have often experienced, when specimens will be discovered that may
illustrate its nature, and prove it to be of considerable interest.
The broken porous bones may be easily repaired by a hot weak solution
of glue; and when the joinings are set, the bone should be saturated
with thin glue, well brushed in, and the surface be sponged clean with
very hot water before the cement is congealed. When dry, the specimens
will be found to possess considerable firmness and durability.[33]
By this process the tusks of mammoths and elephants may be restored,
however much crushed; time, patience, and a little dexterity, only are
required, to convert a heap of mere fragments into a valuable relic of
the ancient world.
[33] A liquid, called "Neuber's liquid glue," is an excellent cement
for this purpose: it is sold at No. 54, New Oxford Street, London.
When the bones are tolerably perfect, but dry and friable from the
loss of their animal oil, they may be made durable by saturating
them with drying oil, and exposing them to a considerable degree of
heat; in this manner the magnificent skeletons of the sloth tribe,
the Megatherium, and Mylodon, in the Hunterian Museum, were prepared.
When a bone appears as if cracked into numerous pieces before its
removal, but still preserves its form, the only method by which it can
be successfully extracted, is by spreading over it a thick layer of
plaster of Paris, which should be used of the consistence of cream;
when it sets, (which, if the plaster be recently prepared, will be in
the course of a few minutes,) the specimen may be carefully extricated,
and the plaster removed or not, according to the nature of the fossil,
and the parts to be displayed. The bones of the large reptiles which
occur in the Wealden and Oolite, may be restored in the same manner.
These remains are generally very brittle, and when imbedded in hard
grit cannot be extracted whole: they will often fall to pieces on the
slightest blow of the hammer or chisel. When of moderate size, it is
best not to attempt their removal from the stone, but to trim the block
into a convenient shape, and carefully chisel away the surrounding
part, so as to expose the essential characters of the bone. In all
cases this is an excellent method where practicable, for such specimens
have a double interest; they are at once illustrative examples of the
fossil, and of the rock in which it was deposited.
But many specimens will not admit of this method; and with large
ones it is inconvenient and undesirable, except where bones lie in
juxtaposition. The large examples in Tilgate grit, (figured in the
Fossils of Tilgate Forest,) were all extracted piecemeal from the rock:
and most of the gigantic bones of the Iguanodon, &c. now in the British
Museum, were originally in many hundred pieces, and were cemented
together with glue in the manner above described; I have found no other
method so convenient and effective.
When a bone is too imperfect to be united as a whole, it may be
imbedded in Roman cement, or plaster of Paris, which when dry may be
coloured of the prevailing tint of the rock. For large heavy specimens,
the cement is preferable; it is of easy application, and the fissures
and cracks of the bones may be filled up with it, taking care first to
cover the parts with thin hot glue, or the cement, when it dries, will
shrink and fall out. A thin coating of mastic varnish will restore the
colour, and by excluding the air, tend to preserve the specimens.
The teeth have generally undergone the same changes as the bones with
which they are associated. The teeth of elephants or mammoths that are
imbedded in loose calcareous earth, like the loam and chalk-rubble of
Brighton cliffs, and of Walton in Essex, are friable, and apt to split
and separate in the direction of the vertical plates of dentine and
bone: the pieces should be glued together, and when set, the tooth be
thoroughly saturated with thin glue, used very hot, and the superfluous
cement removed with a sponge wrung out as dry as possible from boiling
water. If there be any portion of the jaw attached to the teeth, it
must be carefully preserved; and search should be made for fragments of
the articulations, or parts of the joints and sockets.
In argillaceous strata, as the Lias-shale, London Clay, &c., the
fossils are frequently saturated with brilliant pyrites, or sulphuret
of iron; a mineral which decomposes upon exposure to the atmosphere,
and occasions the destruction of the specimens. The fossils of the Isle
of Sheppey are peculiarly obnoxious to this change.
[Sidenote: FOSSIL ANIMAL REMAINS.]
The remains of vertebrated animals in the Lias, very often occur
as skeletons more or less perfect, the entire configuration of
the original being preserved in many instances (_Bd._ pl. 7.
_Petrifactions_, p. 340). But the deposit in which they lie is
generally laminated, and the shale flakes off without great care; much
time, labour, and practice are therefore required, to obtain specimens
of any considerable size. To the late Miss Mary Anning, of Lyme Regis,
the merit is due, of having first accomplished this difficult task;
Mr. Hawkins has subsequently carried the art to perfection, as may be
seen in the marvellous examples of Ichthyosauri and Plesiosauri, in the
British Museum.[34]
[34] Petrifactions, Room IV. chap. iv. pp. 341, 376.
The small specimens, such as the detached paddles, groups of vertebræ
and ribs, &c., that are likely to come under the collector's notice
in his personal researches, are not difficult of preservation. Mr.
Hawkins employed a strong watery solution of gum arabic as the cement,
and plaster of Paris as the ground, using shallow wooden trays of
well-seasoned wood, in which the specimens were permanently imbedded:
the bones, scales, &c. were then varnished with a solution of mastic,
and the ground coloured bluish grey, to imitate the Lias. I have had
considerable practice in the dissection of skeletons imbedded in Lias,
and having found the method previously described answer every purpose,
have not employed that recommended by Mr. Hawkins.
The scales of reptiles and fishes, either in connected masses or
detached, are frequently met with in great perfection, and sometimes
associated with the teeth and bones. In the Lias, even the remains
of the skin and integuments (_Bd._ pl. 10) have been discovered.
Whenever any part of a skeleton is found lying in shale or stone,
the surrounding block should therefore be carefully examined, to
ascertain if there be traces of the skin or integuments, before any
part is removed by the chisel. The specimen of an Ichthyosaurian
paddle, figured in the second volume of this work, affords a good
illustration of the propriety of this caution. Around the bones are
seen the carbonized remains of the cartilaginous fringe that supported
the integuments, and thus the perfect form of the paddle has been
ascertained; had the surrounding stone been chiselled away, the most
important characters would have been obliterated, as probably they have
been in numerous instances.
Nodular masses of indurated clay containing fishes, are often broken
with difficulty in such a manner as will expose the enclosed fossil,
for the nodule generally splits in various directions, and the specimen
is irreparably mutilated or defaced. My friend Sir Woodbine Parish
informs me that by subjecting such nodules to a high temperature--but
not to a red heat--and then plunging them in cold water, they may when
dry, by a properly directed blow of a hammer, be readily fractured in a
direction parallel with the plane of the imbedded fossil, and the fish
be laid bare in the most favourable position.
The scales of fishes, and the integuments of marine reptiles, are not
the only vestiges of the dermal coverings of vertebrated animals that
are preserved by mineralization. Traces of the wing-integument of
flying reptiles, and of the feathers of birds, are sometimes manifest:
and even when every atom of the original structure has perished, the
impression may remain, and afford satisfactory results. The footmarks
of unknown animals are often preserved in the rocks, and the imprints
of the feet of several species of bipeds, presumed to be birds of
colossal size, in tracks as distinct as if but recently made, have been
discovered in the New Red sandstone of North America; in the section on
fossil birds, this highly interesting subject will be fully explained.
The student, even from this brief review, will perceive how many
valuable facts may be unnoticed, and irretrievably lost, unless
attention be paid to the various circumstances under which fossil
remains are presented to his notice.
Of the invertebrated orders, the most durable, and consequently the
most numerous relics, are shells and corals. The integuments of the
eyes, antennæ, and wings of Insects occur; and the shelly coverings
of Crustaceans are not uncommon; those of the Echinoderms, the
Star-fishes, and of the Crinoidea or Lily-animals, are very abundant in
certain deposits. Instructions for the collection and arrangement of
these fossils will be given in the chapters in which they are severally
described.
PART II.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
CHAPTER IV.
FOSSIL BOTANY.
Fossil Vegetables.--The remains of the vegetable kingdom are presented
to the notice of the geologist in various conditions; in some instances
these relics are but little changed in their aspect, as, for example,
in the recent accumulations of mud and silt, at the bottoms of lakes
and rivers, and in morasses, and peat-bogs. In tufaceous incrustations,
the imprints of wood, and of leaves and stems, are often sharply
defined on the solid masses of concretionary and crystalline limestone.
In the ancient deposits, vegetables are found in two different states.
In the one their substance is completely permeated by mineral matter;
it may be calcareous (_lime_), siliceous (_flint_), ferruginous
(_iron_), or pyritous (_sulphuret of iron_); and yet both the external
characters, and the internal structure, may be preserved. Such are the
fossil trees of the Isle of Portland, fragments of which so closely
resemble decayed wood, as to deceive the casual observer, until by
close examination of their texture and substance he finds that they
possess the weight and hardness of stone. In the silicified wood which
abounds in many of the tertiary strata, the most delicate tissues of
the original are preserved, and by microscopical examination (see Pl.
V.) may be displayed in a distinct and beautiful manner. In calcareous
fossil wood the structure is also retained; and in many limestones,
leaves and seed-vessels are well preserved.
The ligneous coverings, or the husks and shells, of nuciferous fruits,
and the cones or strobili of Firs and Pines, are frequently met with in
an excellent state of preservation; in some rare instances indications
of flowers have been observed (_Lign. 67_). The parts of fructification
in some of the fern tribe (_Lign._ 25 and 27), occur in coal-shale,
and in the grit of Tilgate Forest (_Wond._ p. 394): the pollen, and the
resinous secretions of pines and firs, have been discovered in tertiary
marls, and in the Greensand. The well-known substance. Amber, so much
in request for ornaments, is unquestionably of vegetable origin; it has
been found impacted in the trunks of its parent trees (_Wond._ p. 242).
The _fossil resin_ discovered in the London clay, at Highgate and the
Isle of Sheppey, is doubtless referable to the coniferæ found in that
deposit.
In the Clathrariæ of Tilgate Forest, indications of a resinous
secretion have been detected.
The _Diamond_, which is pure charcoal, is probably a vegetable
secretion, that has acquired a crystalline structure by
electro-chemical forces. It has been converted into _Coke_ and
_Graphite_ by the action of intense heat; and the electrical properties
of the substance were changed, the Diamond being an insulator, and the
Coke, a conductor of electricity. (_Wond._ p. 706.)
When the microscope is more extensively employed in investigations of
this kind, it is probable that the siliceous spines and stars which
begem the foliage of many plants (as the _Deutzia_, _Lithospermum
officinale_, &c), will be discovered in a fossil state, for they are
as indestructible as the frustules of Diatomaceæ, and the spicules of
sponges which are so common in flint and chalcedony.
[Sidenote: FOSSIL VEGETABLES.]
But vegetables occur not only as petrified stems, leaves. and fruits,
associated with other remains in the strata, but also in beds of great
thickness and extent, consisting wholly of plants transmuted, by that
peculiar process which vegetable matter undergoes when excluded from
atmospheric influence, and under great pressure, into _Lignite_, and
_Coal_. And there are intermediate stages of this process, in which the
form and structure of the trees and plants are apparent; and a gradual
transition may be traced, from the peat-wood and submerged forests
of modern epochs, in which leaves, fruits, and trunks of indigenous
species are preserved, to those ancient accumulations of carbonaceous
matter, whose vegetable origin the eye of science can alone detect.
For the collection and preservation of fossil vegetables, with the
exception of those which are permeated with. pyrites (as those of
the Isle of Sheppey, &c.), but few instructions are required. The
silicified and calcareous stems are generally easy of extraction, even
when imbedded in hard stone, and if broken can be repaired with glue.
When the stems bear the imprints of leaf-stalks (as in _Lign._ 31 and
54), the surrounding stone should be carefully examined, with the
view of detecting impressions, or other indications of the foliage.
Delicate leaves in clay, or shale, must not be washed; a thin coat of
mastic varnish, or of gum-water, applied with a camel-hair pencil,
will preserve them, and render them more distinct. When a leaf, fruit,
seed-vessel, or other fragile object is attached to clay or friable
sandstone, it is advisable to glue the specimen to a piece of thin wood
or pasteboard, of suitable proportions.
The Sheppey fruits and other fossils permeated with iron pyrites,
generally decompose after a few months' exposure to the air. The
fruits, especially, are liable to decomposition; Mr. Bowerbank keeps
his specimens in bottles of water; a solution of isinglass in spirits
of wine is the best varnish to preserve such fossils, without obscuring
their character and injuring their appearance: but even this method is
often unavailing. The pyritified fir-cones of the Wealden decompose
in like manner: I have had the misfortune to lose several unique and
most instructive specimens from this cause; boiling them in linseed oil
preserves them, but greatly impairs their appearance.
* * * * *
ON THE INVESTIGATION OF THE FOSSIL REMAINS OF VEGETABLES.
Vegetable Organization.--As fragments of the stems, trunks, and
branches, are very often the only vestiges of fossil plants, a
knowledge of the characters by which the principal divisions of the
vegetable kingdom may be distinguished by their internal structure,
is indispensable to the successful investigation of the Flora of the
ancient world. Although I have treated of this subject in the Wonders
of Geology, (_Wond._ p. 694,) it will here be necessary to present the
student with more ample details. The excellent introductory botanical
works of Dr. Lindley, and Professor Henslow, convey full information
on this, and every other department of the science, and should be
consulted by those who intend to make this branch of Geology their
particular study. For the general reader, and amateur collector,
the following brief notice of a few obvious essential characters of
vegetable organization, may perhaps afford sufficient information,
to enable them to understand the principles on which the successful
investigation of the nature and affinities of fossil plants must be
conducted.
[Illustration: Lign. 1.
Sections of Recent Vegetables; illustrative of their internal
organization. (From _Dr. Lindley_.)
Fig. 1.--Longitudinal Section of Coniferous Wood.
_a._ The Ducts,
_b._ Spiral Vessels,
_c._ Glandular vessels.
2.--Transverse section of a dicotyledonous stem.
_a._ Pith, or central column.
_b._ The bark.
_c._ Medullary rays.
_d._ Vascular tissue between the medullary rays.
3.--Elongated cellular tissue, forming the medullary rays.
4.--Transverse section of a monocotyledonous stem.
]
[Sidenote: STRUCTURE OF VEGETABLES.]
Every plant is essentially an aggregation of cells;[35] and the most
simple forms of vegetation consist of a congeries of cells (_cellular
tissue_) of the same kind, and have no visible fructification; such
are the sea-weeds (_algæ_, _conferæ_, &c.), mosses, and lichens. In
the more complex tribes the cells become variously modified, are
elongated into tubes or vessels (_vascular tissue_), some of which
possess a spiral structure, and others have their sides studded with
little glands. The vascular tissue consists of two kinds of vessels.
1. The _spiral vessels_ or _tracheæ_: these are membraneous tubes,
with conical extremities, having within a coil of elastic fibre
spirally twisted, and capable of being unrolled (_Lign. 1, b._).
2. The _ducts_; which are a modification of the structure of the spiral
vessel; their extremities are rounded or conical, and their sides
marked with transverse lines, rings, or bars. Their functions appear to
be different from those of the spiral vessels, and they are found in
situations where the latter never occur.
[35] "A _cell_ in botanical language, means a little bag composed of
membrane, and containing a living substance capable of spontaneous
growth by multiplication, or division of its parts. Of such little
bodies, millions of which may be contained within the space of a cubic
inch, all the soft parts of vegetables are composed; in sea-weeds they
are often of large size."--Dr. Harvey's Sea-side Book, with which the
reader is doubtless familiar.
The organization of the stem in the whole class of flowering plants,
possesses characters so evident, as to afford the most important aid in
the investigation of their fossil remains. Without dwelling on minor
modifications, they are separable into two divisions, namely, the
Endogenous (signifying _to grow from within_), and the Exogenous (_to
grow from without_). Both possess vascular tissue, but so differently
arranged in the two classes, as to constitute distinctive characters
which are seldom obliterated, although what was once a flexible stem,
is now a mass of flint.
Endogenous Stems.--As the seeds of the plants belonging to this
division have but one cotyledon, or _seed-lobe_, as the Lily, they
are also termed monocotyledonous; the reader therefore must remember
that these terms are synonymous. These stems consist of an uniform
mass of cellular tissue, in which bundles of vascular or woody fibre
are imbedded; a transverse section presents a surface dotted over
with spots, produced by the division of these groups of vessels,
pretty uniformly distributed, but more densely arranged towards the
circumference (_Lign. 1, fig. 4_). A slice of cane affords an
illustration of this structure.
The increase of these stems is effected by the formation of new cells
and bundles of vessels in the central axis, which force their way among
the old tissue, and occasion the condensation of the latter towards the
outer edge. These plants have neither pith, concentric circles of woody
fibre, nor true bark; negative characters of the highest importance in
the determination of fossil stems.
Exogenous Stems.--The seeds have two cotyledons, or seed-lobes,
as in the Bean, hence the plants of this class are also called
dicotyledonous. In these stems the cellular tissue forms a central
column, or pith (_Lign. 1, _fig. 2, a_.), and an external band, or
cylinder, called the bark (_fig. 2, b_.); the two being connected by
thin vertical plates, termed medullary rays, which are also formed
of cells (_fig. 2, c, c_.); the diagram, _Lign. 1_, exhibits this
arrangement. The interval between the pith and the bark, and the
interspaces of the vertical radiating plates (_fig. 2, d_.), are
filled up by woody fibre or vascular tissue, consisting of spiral and
other vessels. The ligneous structure of exogenous stems consists,
therefore, of a cylinder formed of wedge-shaped processes, that extend
between the medullary rays to the pith, and is surrounded by the bark;
a new zone of woody fibre is added annually between the bark and the
former cylinder, and from this mode of increase the term _exogenous_
is derived: a transverse section of a branch of oak or ash will show
this structure. The rings, or concentric circles, are the annual zones
of wood; the fine lines radiating from the centre, or pith, to the
circumference, or bark, are the medullary rays (_Lign. 1, fig. 2, c_:
see also _Plate V. fig. 4_).
The organization above described, will be found more or less manifest
in fossil wood, stems, and branches. The monocotyledonous structure is
beautifully displayed in the silicified stems of palms from Antigua
(_Plate V. fig. 1, 1^a._): and the dicotyledonous, in petrified trees
from Egypt. The pith, medullary rays, vascular tissue, and circles of
growth, are preserved in the siliceous and calcareous wood found in
many parts of England.
[Sidenote: STRUCTURE OF CONIFERÆ.]
Structure of Coniferæ (_cone-bearing_).--The remains of a numerous
family of dicotyledonous trees, termed _Coniferæ_, as the pine, fir,
larch, &c., are so abundant in the stratified rocks, that it is
necessary to describe in more detail the peculiarity of structure by
which their stems and branches may be recognised. The most delicate
woody tissue, as we have above stated, consists of elongated cells
or tubes, of two kinds: in the one, the membrane of which they are
composed is smooth: in the other, the walls of the tubes are covered by
little oval or circular bodies called glands (_Lign. 1, fig. 1, c._). A
branch of larch or pine, split longitudinally, and viewed by a powerful
lens, will exhibit the appearance here described. This glandular
structure is so constantly and largely developed in the coniferæ, that
although it is also possessed by other aromatic trees, we shall rarely
err in referring fossil wood in which this organization is apparent,
to this family of vegetables (see _Plate V. figs. 2, 3_). These glands
in the pines and firs, are supposed to be the cells which secrete a
colourless volatile oil, that exudes in the state of turpentine.
From this general account of the vegetable structures that may be
expected to occur in the mineral kingdom, the student will in some
measure be prepared for the investigation of fossil trees and plants;
but for the guidance of those who are wholly unacquainted with the
principles on which the Natural System of Botany adopted in this work,
is founded, I am induced to present the following concise view of the
principal divisions of the vegetable kingdom, though it involves some
repetition.
[Sidenote: BOTANICAL PRINCIPLES.]
The following summary is given nearly in Dr. Lindley's own language:--
Botanical Principles.--One of the first things that strikes an inquirer
into the structure of plants, is the fact, that while all species are
capable of propagating their race, the mode in which this function is
effected is essentially different in different cases. In most tribes
of plants, flowers are produced, and these are succeeded by fruit,
containing seed, which is shed, or scattered abroad, and grows into
new individuals. But in certain families (the _Cryptogamia_), as
Ferns, Mosses, Mushrooms, and the like, neither flowers, nor seeds
properly so called, have been detected; but propagation is effected
by the dispersion of grains or spores, which are usually generated in
the substance of the plant, and seem to have but little analogy with
true seeds. Hence the vegetable kingdom is separated into two distinct
groups, namely, the _flowering_ (_Phanerogamia_), and the _flowerless_
(_Cryptogamia_ or _Agamia_). As the former usually possess a highly
developed system of spiral and other vessels, while the latter are
either altogether destitute of them, or have them only in a few of the
highest orders, and those in a peculiar state, the flowering plants
are termed Vasculares, and the flowerless _Cellulares_. And as all
the flowering, or vascular plants, when they form stems, increase by
an extension of their ends, and a distension or enlargement of their
circumference, but the flowerless or cellular plants form their stems
simply by the addition of new matter to their points, the latter are
called _Acrogens_, signifying increase from the summit.
Flowering plants are also for the most part furnished with respiratory
or breathing organs (_stomata_), of which the flowerless vegetables are
to a great extent destitute.
The flowering or vascular plants are also divisible into two well
marked groups, namely, the _Exogens_, or _Dicotyledons_, and the
_Endogens_, or _Monocotyledons_.
The Exogens (growing from without), increase by the addition of new
woody matter to the outside of the stems beneath the bark; and they are
further characterized by the embryo having two or more cotyledons, or
seed-lobes, hence they are also called _Dicotyledons_; such as the Elm,
Beech, &c.
The Endogens, as we have previously stated, increase by the addition
of ligneous matter to the inside of their stems near the centre; and
as the embryo in this class has but one cotyledon, they are likewise
termed _monocotyledons_, as the Cane, Palm, &c. Again, exogenous
plants have the young external wood connected with a central pith, by
medullary processes; while endogens do not possess such a structure,
having no central pith. In exogens the veins (venation) of the leaves,
are disposed in meshes, like net-work, but in endogens the veins run
parallel to each other.
The number of parts in the flower of an exogenous plant is usually
five, or its multiples: in the endogens it is commonly three, or its
multiples. In the germination, the young root of exogens is a mere
extension of the radicle; but in endogens it is protruded from within.
Thus, in the flowering or vascular plants, we have two groups distinct
from each other in their germination, the structure of their stems
and leaves, their mode of growth, the arrangement of the parts of the
flower, and in the structure of the embryo.
The vegetable kingdom is thus separated into three natural classes,--1,
the _Exogens_, 2, the _Endogens_, 3, the _Acrogens_; but there are
likewise other divisions, a knowledge of which is of great importance
in the study of fossil botany; the sub-class termed Gymnosperms
especially requires notice.
In the strictly exogenous and endogenous plants, the fertilizing
principle is communicated to the young seeds through the medium of a
_stigma_ and _style_, that terminate the case or pericarp in which the
seeds are enclosed: but in another important group of the vegetable
kingdom, the pollen is directly applied to the ovule, without the
intervention of any pericarpial apparatus; hence these are termed
_Gymnosperms_, signifying naked seeds. These plants have the same
relation to the other exogens, as frogs and analogous reptiles bear to
the other orders of their Class; they comprise the two natural orders
_Coniferæ_, and _Cycadaceæ_.
The Gymnosperms also possess peculiarities of a subordinate nature:
thus, many kinds have more than two cotyledons, and are therefore
termed _polycotyledons_; again, the radicle usually adheres to the
albumen in which the embryo lies, hence they are sometimes named
_Synorhiza_. The veins of the leaves (in those whose leaves are
veined), are either simple or forked; in which respect they approach
the endogens on the one hand, and the acrogens on the other.
This concise definition of the natural divisions of the vegetable
kingdom will enable the reader to comprehend the botanical principles
which must guide him in his attempt to explore the ancient floras,
whose fossil remains are generally found in a very fragmentary
condition.
I need only add that M. Ad. Brongniart, in his great work on Fossil
Plants, arranges the vegetable kingdom into five classes, viz.:--
1. Cellular Cryptogamia,[36] or Amphigens.
2. Vascular Cryptogamia,[37] or Acrogens.
3. Monocotyledons.[38]
4. Gymnospermous Dicotyledons.[39]
5. Angiospermous Dicotyledons.[40]
[36] Plants having the fructification concealed, and of cellular
structure only.
[37] Plants having the fructification concealed, and with vessels, or
vascular tissue.
[38] Flowering plants with one cotyledon; the Endogens.
[39] Plants with naked seeds; that is, destitute of a pericarp or case.
[40] Plants with the seeds in a receptacle or pericarp, with a style
and stigma.
ON THE MODE OF INVESTIGATING FOSSIL REMAINS OF VEGETABLES.
[Sidenote: INVESTIGATION OF FOSSIL PLANTS.]
The distinguished authors of the British Fossil Flora justly remark,
that a few isolated, and very imperfect data, exclusively afforded by
the remains of the organs of vegetation, are but too often the sole
guide to the class, order, or genus of the fossil plants which the
geologist has to examine; hence, in most instances, a general idea
only can be obtained of the nature of the original.[41] To facilitate
the study of Fossil Botany they offer some practical suggestions,
which have served as the basis of the following directions for the
investigation of vegetable remains, and which the previous remarks
will, we trust, render intelligible.
[41] Foss. Flor. vol. I. p. xxvi.
1. _The Trunk, or Stem._--Examine if the wood in a transverse section
be disposed in concentric circles (as _Plate V. fig 4_): if so, it
belonged to an exogenous tree: if, on the contrary, the wood appears
deposited irregularly in spots (_Lign. 1, fig. 4_), then the original
was endogenous. If a transverse section show remains of sinuous,
unconnected layers, resembling arcs with their ends directed outwards,
and of a solid structure, and imbedded among looser tissue, then it
belonged to an arborescent fern; see the subjoined figures (_Lign. 2_).
[Illustration: Lign. 2. Sections of Fern-Stems.
Transverse sections (half the diameter) of two stems of recent
Arborescent Ferns, to show the zone of woody fibre disposed in arcs.
This structure is seen in the silicified trunks from Chemnitz.]
[Sidenote: INVESTIGATION OF FOSSIL STEMS.]
If the stem be in a state of preservation that will admit of the
slicing or chipping off a piece for microscopical investigation, the
process described at the conclusion of this section should be employed.
The following data may be thus obtained. If the structure be entirely
cellular, and it can be satisfactorily ascertained that it never
possessed vascular tissue, the original belonged to the _Cryptogamia_;
_i.e._ to fuci, mosses, and the like.
If it consist of parallel tubes, and has neither pith, nor rays
passing from the centre to the circumference, the tree or plant was
_endogenous_, like the Palm. If any trace be present of tissue crossing
the longitudinal tubes at right angles, and radiating from the centre
to the circumference, this will prove the existence of medullary rays,
and the original must have been _exogenous_, as the Oak, Elm, &c.: and
if in a transverse section the tubes appear of equal size, the tree was
probably _coniferous_, or _cycadeous_ (_i.e._ related to the plants
called _Cycas_ and _Zamia_); but if larger tubes appear among the
smaller ones, disposed in a definite manner (see _Plate V. fig. 4_),
it belonged to some other tribe of exogenous plants.
If the walls of the tubes be studded with glands (_Lign. 1, fig. 1,
c_; _Plate V. figs. 2^b 3^b_.); the fossil belongs to the Coniferæ.
If any vestige of a central pith be discovered, the exogenous nature of
the original is undoubted, for no other class, as we previously stated,
possesses a central cellular column.
The absence or presence of a true cortical investment, or bark, is
important, for a distinct bark is the characteristic of the _exogenous_
class:[42] a cortical integument, or rind, not separable from the
enclosed structure, indicates the _monocotyledons_; and the entire
absence of any rind, the _cryptogamia_.
[42] An apparent exception to this rule is found in the fossil genus
Clathraria, described hereafter, which has a distinct hollow cortical
cylinder, that separates from the internal axis: this is not true bark,
but is formed by the consolidation of the bases of the petioles or
leaf-stalks; see _Lign. 54_.
The markings on the stems, occasioned by the scars or cicatrices left
by the separation of the petioles or leaf-stalks (as on the stalk of a
cabbage), afford important evidence, since they are commonly present,
even when the cylindrical trunk is compressed into a flat thin layer of
coal; as we shall often have occasion to remark. In this place it need
only be stated, that by these scars may be detected the position of the
leaves, and the form of the bases of the petioles or leaf-stalks; their
probable direction, whether they were opposite, alternate, verticillate
or spirally disposed, deciduous or persistent, imbricated or remote.
Even when no traces of the leaves remain, the origin of the branches,
and their bifurcation, may perhaps be determinable.
2. _The Leaves._--In a fossil state the texture and surface of the
leaves are sometimes preserved; but in general the outline of the leaf,
its division and arrangement, and its mode of venation, can alone be
ascertained. The _venation_, that is, the form and distribution of the
vascular tissue, or vessels, through the leaf, is the most important
character for our guidance; and Dr. Lindley offers the following
suggestions on this point. If the veins be all parallel, not branched,
or only connected by little transverse bars, and the leaves undivided
(as in the Lily or Hyacinth), the plant was probably endogenous; but
if the leaf be divided or pinnated, it may be referable to Cycadeæ
(_Lign. 45_).
Leaves having the veins of equal, or nearly equal thickness, and
dichotomous (_forked_), or very fine, and simply divided, belong to the
fern tribe; to this division an immense proportion of the foliage found
in the carboniferous strata is referable; the genera of fossil ferns
have been constructed principally from the venation.
If the veins of a leaf be obviously of unequal thickness, and
reticulated, or disposed in net-like meshes, as in the rose and apple,
the original was dicotyledonous (_Plate III, figs. 4, 8_).
Leaves of a large size, destitute of veins, and irregularly divided,
probably belong to fuci, or other marine plants (_Lign. 10_).
Such are the rules for the investigation and interpretation of
the characters of stems and foliage, which have been preserved by
mineralization. Their application is not difficult, and the student may
by their assistance obtain some general indications as to the nature of
the original trees or plants, whose petrified remains form the subject
of his examination.
ON THE MICROSCOPICAL EXAMINATION OF FOSSIL VEGETABLES.
[Sidenote: MICROSCOPICAL EXAMINATION.]
Mr. Nicol, who first suggested the method now generally adopted for
preparing fossil wood, coal, &c. for microscopical examination, and
which was employed by Mr. Witham in the illustrations of his beautiful
work on the structure of fossil plants,[43] has so clearly explained
the process, that by a little practice the student will be able to
prepare specimens sufficiently thin for every useful purpose. Several
lapidaries in London, (see list at the end of this work,) polish and
mount fossil vegetables and other substances, in a very superior
manner; but their charges are high, and they frequently injure
specimens by grinding them too thin, and thus obliterating structure.
I would recommend that a small chip of the specimen, if possible in
a _radial_ direction, should be examined by reflected light, always
beginning with the lowest object-glass and eye-piece, and ascending to
the highest power; at first without any preparation;[44] subsequently
the object should be immersed in oil of turpentine, which will render
it somewhat transparent, and it then should be examined by transmitted
light. By this exploration we may detect structure, and ascertain if
the specimen be worth the trouble or expense of further preparation.
[43] Observations on Fossil Vegetables. 4to. 1833.
[44] The drawings in _Plate V. figs. 2 and 3_, of fossil coniferous
wood, were from chips seen by reflected light, and without any
preparation.
Coal may be prepared for examination, by removing with a sharp knife
a thin pellicle, or a minute scraping; immerse it in a drop of oil
of turpentine on a piece of glass; then add a little Canada balsam,
and hold the glass over the flame of a lamp till the balsam is spread
evenly over the specimen. But without any preparation, the surface of
coal recently broken may be successfully investigated. One of the most
interesting examples of coniferous structure in coal that my cabinet
contains, was discovered by my son in a piece lying on the fire, which
had been cracked by the heat; and I have another fragment, showing
the spiral vessels, and coniferous glands, which the Rev. J. B. Reade
obtained under similar circumstances. But for choice specimens, the
following method is to be employed; and in many cases no other plan
will succeed. Sections of teeth, bone, marble, &c. may be prepared by a
like process.
MODE OF PREPARING SLICES OF FOSSIL WOOD FOR MICROSCOPICAL EXAMINATION.
"Let a thin slice be cut off from the fossil wood, in a direction
perpendicular to the length of its fibres--the slice thus obtained must
be ground perfectly flat, and polished. The polished surface is then to
be cemented to a piece of plate glass (3 in. long and 1 in. wide) by
Canada balsam--a thin layer of balsam must be applied to the polished
surface of the slice, and also to one side of the glass--the slice and
the glass are now to be laid on any thin plate of metal, and gradually
heated over a slow fire, or a spirit lamp, to concentrate the balsam.
The heat must not be so great as to throw the balsam into a state of
ebullition; for if air bubbles be formed, it is difficult to get rid
of them, and if not removed they will prevent the complete adhesion
of the two surfaces when applied to each other; the heat of the metal
should never be so great that the fingers may not be held in contact
with it for a few seconds without inconvenience. When air bubbles are
formed, they should be displaced by a small piece of wood tapering to
a point; when the balsam is thought to be sufficiently concentrated,
and all the air bubbles have disappeared, the slice and glass may be
taken from the heated metal, and pressed closely together; a slight
degree of pressure will suffice to expel the super-abundant balsam, and
this will be facilitated by gently sliding the specimen to and fro on
the glass; by this kind of motion any air that may have got entangled
when the two surfaces were brought in contact, will also be removed.
When the whole is cooled down to the temperature of the air, and the
balsam has become solid, that part which adheres to the surface of the
glass surrounding the slice should be scraped off with the point of a
penknife; and by this operation, it will at once be seen whether the
balsam has undergone the requisite concentration; for if it flakes off
before the knife, it will be found that the slice and glass will cohere
so firmly, that in the subsequent grinding, there will be no risk
of their separating from each other; but if the balsam has not been
sufficiently concentrated, it will slide before the knife, and in that
case the two bodies will not adhere with requisite firmness. If the
layer of balsam applied to the two surfaces be not too thick, its due
concentration will be accomplished in four or five minutes, provided
the application of the heat be properly regulated. The slice must now
be ground to that degree of thinness which will permit its structure
to be seen by the help of a microscope. This will be accomplished by
rubbing the slice, by a rapid circular motion with the hand, on a piece
of sheet lead, supplied with a little emery (_size_ No. 1.) moistened
with water; when the emery ceases to act, the muddy matter remaining
should be removed, and a fresh portion of emery applied; this must be
repeated until the surface of the slice is perfectly flat; a sheet of
copper must then be substituted for the lead, and the fossil ground as
smooth as possible by flower of emery, freed from its coarser parts.
The surface may then be polished by friction, with _crocus_ or rotten
stone, on a transverse section of any soft wood."[45]
[45] Mr. Witham, Observations on Fossil Vegetables.
CHAPTER V.
ON PEAT-WOOD, LIGNITE, AND COAL.
[Illustration: Lign. 3. Nodule of Ironstone inclosing a Fern-leaf.
_Coalbrook Dale._
Fig. 1.--The nodule in its natural state.
2, 3.--The same, split open longitudinally. The leaf
remains attached to fig. 2, and the impression
of its upper surface is seen on fig. 3.
4.--Outline of the form of the leaf, which is a species
of Pecopteris.
]
[Sidenote: PEAT-WOOD, LIGNITE, AND COAL.]
Before entering upon the examination of the specific and generic
characters of fossil plants, and the natural relations of the extinct
forms with those of the existing Floras, it will be requisite to
notice those vast beds of vegetable matter, in various states of
carbonization, which occur in the palæozoic, secondary, and tertiary
formations.
Submerged Forests. Peat.--The phenomenon of extensive tracts of
marsh-land, with layers of prostrate trees of all ages, lying but a
few feet beneath the common alluvial soil, is of frequent occurrence,
both inland, and in many places along the shores of our island. (_Geol.
S. E._ p. 18). These submerged forests are generally situated below
the level of the sea, and afford unquestionable proof of subsidences
of the land. The trees are of the kinds indigenous to the districts
in which they occur; and leaves and seeds of the hazel, beech, elm,
&c. are often preserved in the silt in which the prostrate forests are
imbedded. On the Sussex coast there are accumulations of this kind, at
Bexhill, Pevensey levels, Felpham, &c.
The extensive subterranean forests exposed in the Fens of Lincolnshire
by the operations carried on for draining that district, must be
familiar to those who travel by the Great Northern Railway: the
protruding upright stems, broken off at a short distance above the
primitive soil, will remind the geological observer of the petrified
forest of the Isle of Portland.
The wood in these cases has undergone no change but that of being dyed
black, by an impregnation of solutions of iron; and many trunks are
in so sound a state as to be employed in building. The oak timbers of
the Royal George, lately raised up from off Portsmouth, after being
immersed in silt about sixty years, closely resemble in colour and
texture the wood of the submerged forests. Skeletons of deer, horse,
swine, &c. are occasionally found imbedded in these subterranean
accumulations of vegetable remains; and sometimes canoes, formed of the
trunk of an oak, constructed by the aboriginal inhabitants of Britain,
with stone implements called celts, are met with at considerable depths.
In the peat-bogs of Ireland (_Wond._ p. 66), large forest trees often
occur, together with the skeletons of the elk, deer, and other animals
of the chase; and in a few instances the bodies of the primitive
hunters, wrapped in skins, have been discovered.
In Belfast Lough, a bed of peat is situated beneath the ordinary level
of the waters, but is generally left bare at the ebb tides. Trunks and
branches of trees, with vast quantities of hazel nuts, are imbedded in
the peat; the whole being covered by layers of sand, and blue clay, or
silt. In most cases the pericarps of the nuts are empty, the kernels
having perished; but on the eastern side of the Lough, which is bounded
by limestone rocks, they contain calc-spar, which in some examples
forms a lining of delicate crystals (_Plate V. fig. 6_); while in
others the kernel is transmuted into calcareous spar (see _Plate III.
fig. 7_); but the pericarps are unchanged, and in the state of common
dried nut-shells; the water which deposited the spar in their cavities
not having left a particle of mineral matter in the ligneous substance
through which it had filtrated.
In a subterranean forest at Ferry-bridge, Yorkshire, hazel nuts in a
similar mineralized state occur, and the branches and stems of the
trees have undergone a like change; the central ligneous axis is
petrified, while the outer zones have undergone no lapidification, but
remain in the state of dry rotten wood.[46]
[46] Specimens are preserved in the Museum at York.
[Sidenote: PEAT.--LIGNITE.--BROWN COAL.]
Lignite, Brown Coal, or Cannel Coal; these are terms employed to
designate certain varieties of carbonized wood, in which the ligneous
structure is more or less distinctly preserved. Lignite may be regarded
as an imperfect coal, for in its chemical properties it holds an
intermediate place between peat and bituminous coal. It is for the most
part found in tertiary formations, but is not unfrequent in ancient
secondary deposits, and may occur in the earliest sedimentary rocks
which contain vegetable remains.
The newer deposits of _Brown or wood-coal_, are commonly situated in
depressions or basins, as if they had been produced by the submergence
of woods and forests, in a swamp or morass; and in many instances the
ligneous structure is distinct in one part of the bed, while in another
the mass is a pure black coal, differing in no respect from true coal,
except that it is less dense.
_Bovey Coal._--One of the most instructive deposits of brown coal in
England, is that of Bovey Heathfield, near Chudleigh in Devonshire,
which is of considerable thickness and extent, and presents all the
characters of a true coal-field; namely, beds of carbonized vegetables,
alternating with layers of clay and marl. The Bovey coal is in the
state of bituminized wood, the vascular tissue (which is coniferous in
the specimens that have come under my notice) being apparent. It is
easily chipped or split, and leaves a considerable quantity of white
ashes after combustion. The layers of coal vary in thickness from one
foot to three feet; and there are eighteen or twenty in a depth of
about 120 feet; this coal-field extends seven or eight miles. No leaves
or fruits have been discovered; bitumen occurs both in the coal and
in the intermediate clays. Calcareous spar, and iron pyrites, prevail
in many of the strata. In some places this brown coal is covered by a
bed of peat, in which trunks and cones of firs are imbedded. The whole
series appears to have been a lacustrine deposit; probably formed in a
lake, into whose basin rafts of pine forests were drifted by periodical
land-floods. (Org. Rem. I. p. 327).
The brown-coal formations on the banks of the Rhine, present the same
phenomena on a more extended scale, and complicated with changes
induced by volcanic action. In Iceland, where at the present time
forests are unknown, there are extensive deposits of lignite of a
peculiar kind, termed _surturbrand_.
[Sidenote: JET.--WEALDEN COAL.]
_Jet._--The beautiful substance called Jet, is a compact lignite,
and the vascular tissue may be detected even in the most solid
masses; when prepared in very thin slices, it appears of a rich brown
colour by transmitted light, and the woody texture is visible to the
naked eye. Jet is found in great purity and abundance in the cliffs
of alum-shale on the Yorkshire coast, which were celebrated in the
early centuries for the production of this substance. At Whitby and
Scarborough extensive manufactories of ornaments and trinkets of jet
are established. The sandstone cliffs near Whitby contain masses of a
very compact variety, locally termed stone-jet. In the front of the
cliff, on the north-west side of Haiburn Wyke, the stump of a tree
was observed in an erect position, about three feet high, and fifteen
inches in diameter; the roots traversed a bed of shale, and were in the
state of coarse jet, but the trunk, which extended into the sandstone,
was in part silicified, while other portions were decayed and had a
sooty aspect.[47]
[47] Geological Survey of the Yorkshire Coast; by Rev. G. Young; 1828;
p. 197.
Thin seams and layers, and nodular masses, as well as regular
coal-fields of lignite, occur in the tertiary formations. At Castle
Hill, near Newhaven, in Sussex (_Wond._ p. 239), a seam of lignite
resembling the surturbrand of Iceland, a few inches thick, is
interposed between strata of red marl in which are carbonized leaves of
dicotyledonous trees.
At Alum Bay in the Isle of Wight, a layer of lignite occurs between the
beds of vertical gravel and sand of that interesting locality.
Wealden Coal.--The Wealden formation, in some districts, contains
layers of lignite, which alternate with finely laminated micaceous
sandstones, marls, and clays, abounding in minute carbonized
fragments of fern-leaves, with fresh-water shells, and entomostracous
crustaceans. This series of strata so strikingly resembles in its
general aspect the characters of a coal-field, that some years since
extensive works were undertaken in Sussex, in the expectation that
coal might be obtained of suitable quality for economical purposes.
The search was unsuccessful, but the attempt deserves not the censure
that was bestowed upon it, in the infancy of geological science;[48]
for experience has since shown, that although the true coal-measures
are only found beneath the Triassic and Permian formations, good
combustible bituminous coal is not necessarily restricted to any period
or series of strata, but may occur wherever the local conditions
were favourable to the accumulation and bituminization of vegetable
matter. In fact, the coal-fields of the north of Germany are of the
Wealden epoch; and this coal more closely approaches in its chemical
characters the black-coal of the ancient carboniferous formations,
than any of the lignites and brown-coals of the tertiary strata. Some
of the beds are highly bituminous, especially those of Schaumberg,
and of the principality of Bückeburg, which may rank with the best
English Newcastle coal; but those layers which are derived from
coniferous trees and plants are more laminated, and somewhat resemble
the brown-coal. These deposits have originated for the most part from
carbonized conifers and cycads, with a few ferns and lycopodiaceæ, or
club-mosses.
[48] See Sir J. F. W. Herschel's Discourse on Nat. Phil.
The brown-coal of Hohen-Warte by the Osterweld, is chiefly formed
of the _Abies Linkii_, and _Pterophyllum Lyellianum_, whose leaves
and twigs, closely impacted together, are generally of a brownish
colour, have a glossy surface, and, when soaked in water, are
perfectly flexible. The other modification of Wealden coal appears to
have undergone a greater degree of pressure, and of exclusion from
the atmosphere; no ligneous structure is apparent, but indistinct
impressions of leaves are perceptible, and these are chiefly of ferns
and club-mosses. This coal has probably resulted from an accumulation
of plants of less firm texture, and more perishable, than those of
which the former is composed.[49]
[49] See Dr. Bunker's Mon. Norddeutsch. Weald.
Many interesting facts relating to the carbonization of vegetables,
came under my observation during my researches in the Wealden strata;
and it is a subject of regret to me, that circumstances prevented my
following up the investigation of those still imperfectly explored
deposits. Small nodular portions of coal, in which no structure is
apparent, often occur in the calciferous grit of Tilgate Forest; and
sometimes large masses of lignite, fissured in every direction, and
having the interstices filled with white calcareous spar.[50] Some of
the sandstones are discoloured by the abundance of minute particles
of lignite, produced by the disintegration of ferns peculiar to the
country of the Iguanodon.
[50] A fine specimen of this kind is in the British Museum.
The original structure and composition of a plant doubtless affected
its carbonization; for in the same layer of stone, the stems of
Endogenites, hereafter described, invariably possess a thick, outer
crust, of coal; while those of Clathrariæ, plants allied to the Cycads,
have not a particle of carbonaceous matter, but are surrounded by a
reddish brown earthy substance. The nature of the stratum in which
the plants were imbedded, must also have influenced the process
of bituminization. Masses of vegetables buried beneath beds of
tenacious clay, by which the escape of the gaseous elements set free
by decomposition was prevented, must have been placed under the most
favourable conditions for their conversion into lignite and coal.
That the production of lignite is still going on there can be
no doubt; and the following instance of a bed of recent origin,
affords an instructive illustration of the subject. Near Limerick,
in the district of Maine, one of the States of North America,
there are peat-bogs of considerable extent, in which a substance
similar to cannel-coal is found at the depth of three or four feet
from the surface, amidst the remains of rotten logs of wood, and
_beaver-sticks_:[51] the peat is twenty feet thick, and rests upon
white sand. This coal was discovered on digging a ditch to drain a
portion of the bog, for the purpose of obtaining peat for manure. The
substance is a true bituminous coal, containing more bitumen than is
found in any other variety,[AZ] Polished sections of the compact masses
exhibit the peculiar structure of coniferous trees, and prove that the
coal was derived from a species allied to the American fir.
[51] Pieces of wood fashioned by the beavers for the construction of
their dams.
[52] An analysis of 100 grains gave the following results:--Bitumen 72;
carbon, 21; oxide of iron, 4; silica, 1; oxide of manganese, 2; = 100.
[Sidenote: COAL.]
Coal.--We proceed to the examination of that remarkable substance which
has resulted from the perfect bituminization of the vegetables of the
most ancient Flora which geological researches have brought to light,
and to which the term _Coal_ is commonly restricted.
Although Balthazar Klein in the sixteenth century affirmed that coal
owed its formation to wood and other vegetable substances,[53] yet I
can well remember when many eminent geologists were sceptical on this
point; and the truth in this, as in most other questions of natural
philosophy, was established with difficulty. The experiments and
observations of the late Dr. Macculloch, mainly contributed to solve
the problem as to the vegetable nature of this substance; and that
eminent chemist and geologist successfully traced the transition of
vegetable matter from peat-wood, brown-coal, lignite, and jet, to
coal, anthracite, graphite, and plumbago. Nor must the meritorious
labours of that accomplished naturalist, and excellent man, the late
Mr. Parkinson, author of the "_Organic Remains of a Former World_,"
in this field of research, be forgotten.[54] The first volume of that
work, which treats on fossil plants, contains much original information
on the transmutation of vegetables into the various mineral substances
in which the nature and original structure of the originals are
altogether changed and obliterated; it may still be consulted by the
student with advantage.
[53] Sternberg's "Flore du Monde Primitif."
[54] See my "Pictorial Atlas of Organic Remains," 1850.
Although the vegetable origin of all coal will not admit of question,
yet evidence of the internal organization of the plants of which it
is composed, is not always attainable; for the most perfect coal
has undergone a complete liquefaction, and if any portions of the
structure remain, they appear under the microscope as if imbedded in
a pure bituminous mass. The slaty coal generally preserves traces of
cellular or vascular tissue, and the spiral vessels, and the dotted
cells of coniferous trees, may readily be detected in chips or slices,
prepared in the manner previously pointed out (_ante_, p. 66). In
many examples the cells are filled with an amber-coloured resinous
substance; in others the organization is so well preserved, that on
the exposed surface of a piece of coal cracked by exposure to heat,
the vascular tissue, spiral vessels, and cells studded with glands,
may be detected. Even in the white ashes left after combustion, traces
of the spiral vessels are often discernible under a highly magnifying
powder. Some beds of coal are wholly composed of minute leaves and
disintegrated foliage; and if a mass recently extracted from the mine
be split asunder, the surface is seen to be covered with flexible
pellicles of carbonized leaves and fibres, matted together; and flake
after flake may be peeled off through a thickness of many inches,
and the same structure be apparent. Rarely are any large trunks or
branches observable in the coal; the appearance of many beds being that
of a deposit of foliage, shed and accumulated in a forest, (as may be
observable in existing pine-districts,) and consolidated by pressure,
while undergoing that peculiar change by which vegetable matter is
converted into a carbonaceous mass.
In fine, a gradual transition may be traced from the peat-wood and
submerged forests of modern times, in which leaves, fruits, and trunks
of indigenous trees and plants are preserved, to those vast deposits of
mineral coal, formed by the bituminization of the extinct Floras which
flourished in the palæozoic ages.
The geological position of the ancient coal, the manner in which it
is interstratified with layers of clay, shale, micaceous sandstone,
grit, and ironstone--in some districts associated with beds of
fresh-water shells (_Sil. Syst._ p. 84)--in others alternating with
strata containing marine remains,--are fully treated of in _Wond._
pp. 729-733, and _Bd._ p. 525; and it is not within the scope of the
present work to dwell in detail upon what may be termed the physical
geology of the carboniferous deposits. But a few observations on the
phenomena presented by these accumulations of bituminized vegetables
and their associated strata, are necessary to render the subsequent
remarks on the habits and affinities of the plants composing the
palæozoic Flora intelligible to the general reader.
While the essential conditions for the conversion of vegetable
substances into coal appear to be the imbedding of large quantities
of recent trees and plants in a deposit which shall exclude the air,
and prevent the escape of the gaseous elements when released by
decomposition from their organic combination, so, according to the
more or less perfect manner in which these conditions are fulfilled,
will result coal, jet, lignite, brown-coal, or peat-wood; or a mass of
partially carbonized vegetables, like that observable when new-mown
hay undergoes spontaneous combustion, from bituminous fermentation in
the atmosphere (_Wond._ p. 701. _Org. Rem._ I. p. 181).
The manner in which the carboniferous strata have been deposited, has
been a subject of much discussion. Some contend that the coal-measures
were originally in the state of peat-bogs, and that the successive
layers were formed by the subsidences of forests which grew on the
sites now occupied by their carbonized remains; others suppose
that the vegetable matter originated from rafts, like those of the
Mississippi, which floated out to sea, and became engulfed; while
many affirm that the coal-measures were accumulated in inland seas
or lakes, the successive beds of vegetable matter being supplied by
periodical land-floods; and the supporters of each hypothesis bring
numerous facts in corroboration of their respective opinions. There
can, I think, be no doubt that the production of coal has taken place
under each of these conditions, and that at different periods, and in
various localities, all these causes have been in operation; in some
instances singly, in others in combination. Coal may have been formed
at the bottom of fresh-water lakes, as in those instances where it is
associated with fresh-water shells and crustaceans, as at Burdie House
(_Wond._ p. 693), and in some of the Derbyshire and Yorkshire deposits;
in the beds of rivers and estuaries, as in the Wealden, and in the
Shrewsbury coal-field;[55] and from drifted forests, like the rafts
of the American rivers, transported into the sea, and engulfed in the
abyss of the ocean;[56] and the remains of terrestrial, lacustrine,
and marine animals, may accordingly be found associated with it.[BE]
But though many coal-fields (or basins, as they are termed, because
they occupy depressions) have evidently been produced by different, and
local agencies, the sedimentary deposits and coal-beds comprised in the
carboniferous formations, setting aside unimportant variations, present
a remarkable uniformity of character in their nature and arrangement,
not only throughout Great Britain and Europe, but in every other part
of the known world.
[55] In this coal-field are beds of limestone several feet thick,
abounding in cyprides, fresh-water mollusks, &c.--_Sil. Syst._ p, 84.
[56] The immense thicknesss of some coal-beds, without any
intercalations of earthy materials, seems to be inexplicable on any
other supposition but that of accumulations of drift-wood and plants.
In the Great Exhibition of 1851, there was exhibited, on the outside of
the west end of the Crystal Palace, a section of the lowest bed of coal
from Tividale Colliery in South Staffordshire, the total thickness of
which was 29 feet, with no intermixture whatever of sediment, except
some thin shaly partings: the entire mass was composed of carbonized
vegetables.
[57] Sir R. I. Murchison has treated this subject with great ability:
see _Sil. Syst._ chap, xi., and the illustrative maps opposite, p. 152.
[Sidenote: STRATIFICATION OF A COAL-FIELD.]
Stratification of a Coal-field.--The group of strata constituting a
coal-field consists of an alternation of layers of coal and of clay,
of variable thickness, resting, very generally, on grit, or marine
limestone abounding in shells, corals, and crinoidea.
My late excellent friend, Mr. Bakewell, used to exemplify the
manner in which the beds of coal are interstratified with layers of
clay and shale, by the following apt illustration; let a series of
mussel-shells be placed one within the other, and a layer of clay be
interposed between each; the shells will represent the beds of coal,
and the partitions of clay the earthy strata intercalated between the
carboniferous layers; now, if one side of the series of shells be
raised to indicate the general rise of the strata in that direction,
and the whole be dislocated by partial cracks and fissures, the general
arrangement and subsequent displacement of the beds will be represented.
The principal feature which arrests attention on the examination of
the section of a coal-pit, is the uniform presence of a thick bed
of clay beneath every layer of coal; but a still more extraordinary
fact remains to be mentioned, namely, that a common plant of the
coal strata, called Stigmaria, (hereafter described, see _Lign.
36, 38_,) invariably occurs, more or less abundantly, in this bed of
under-day, although very rarely to be met with in the coal or shale
above. This phenomenon, long since noticed by Martin, Macculloch, and
other authors, but whose value was not duly estimated till the recent
observations of Mr. Logan, (_Geol. Proc._ vol. iii. p. 275,) is also
found to prevail throughout the Welsh coal formation, which is upwards
of twelve thousand feet in thickness, and contains more than sixty
beds of coal, and as many of clay with stigmariæ; the Appalachian
coal-measures of the United States present the same characters.[58] To
place this fact before the student in a clear point of view, I will
describe one of the triple series of beds which compose a coal-field.
[58] See Prof. Rogers, in the Proceedings of the American Geologists,
p. 453; and Sir C. Lyell's Travels in America.
1. _Under-clay_; the lowermost stratum. A tough argillaceous substance,
which upon drying becomes a grey friable earth: it is occasionally
black, from the presence of carbonaceous matter. It contains
innumerable stems of stigmariæ, which are generally of considerable
length, and have their rootlets or fibres (see _Lign. 38_) attached,
and extending in every direction through the clay: these stems commonly
lie parallel with the planes of the bed, and nearer to the top than to
the bottom.
2. _Coal._ A carbonized mass, in which the external forms of the plants
and trees composing it are obliterated, but the internal structure
remains; large trunks or stems, and leaves, are rarely distinguishable
in it, but the presence of coniferous wood in many beds of coal, proves
that this arises, not from the absence of trees, but from their
external forms having been obliterated.
3. _The Roof_, or upper bed. This generally consists of slaty clay,
abounding in leaves, trunks, stems, branches, and fruits, and
contains layers and nodules of ironstone, inclosing leaves, insects,
crustaceans, &c.
In some localities beds of fresh-water mussels, and in others of marine
shells, are intercalated; layers of shale, finely laminated clay,
micaceous sand and grit, and pebbles of limestone, granite, sandstone,
and other rocks, are often present. The most illustrative examples
of the foliage of the carboniferous flora are found in this deposit,
which appears to be an accumulation of drifted materials derived from
other rocks, and promiscuously intermingled with the dense foliage and
stems of a prostrate forest; the whole having been transported from a
distance by a powerful current or flood.
[Sidenote: ORIGIN AND NATURE OF COAL.]
Thus we have, in the first place, spread uniformly over the bottom,
and constituting the bed on which the coal reposes, a stratum of clay
(_Under-clay_), composed of fine pulverulent materials, which may have
once constituted the soil of a vast plain or savannah; the only remains
found in it are the roots of gigantic trees (see _Lign. 36_); for such
the stigmariæ are now proved to have been, and not aquatic plants, as
was formerly supposed (_Bd._ p. 476).
Secondly, a bituminous mass (Coal), composed of coniferous wood,
gigantic ferns, club-mosses, &c.; occasionally with trunks of trees
penetrating vertically through it.
Thirdly, a deposit of drift or water-worn materials (_the Roof_), mixed
with the foliage and stems of numerous species of terrestrial plants;
the whole appearing to have been subjected to the action of currents.
The first, or _Under-clay_, may have been the natural soil, in which
the stigmariæ grew; the next,--the _Coal_,--the carbonized stems, and
other remains of the trees to which the roots belonged: and the last,
or uppermost, forming the roof of the coal, may have resulted from
the foliage and branches of a prostrate forest, overwhelmed and buried
beneath the transported detritus of distant rocks.
These phenomena may be explained by supposing the inundation of a
thickly-wooded plain from an irruption of the sea; or of a vast
inland lake, occasioned by the sudden removal of some barrier; or
by a subsidence of the tract of country on which the forest grew.
But when we find an accumulation of strata, in which triple deposits
of this kind are repeated some thirty or forty times through a
thickness of many thousand feet, this solution of the problem is not
satisfactory. Not only subsidence after subsidence must have taken
place, but the first submergence have been followed by an elevation
of the land--another soil, fit for the growth of forest trees, must
have been produced--another generation of vegetables, of precisely the
same species and genera, have sprung up, and arrived at maturity--and
then another subsidence, and another accumulation of drift. And these
periodical oscillations in the relative level of the land and water
must have gone on uninterruptedly through a long period of time, not
in one district or country only, but in various parts of the world,
during the same geological epoch. At present I do not think we have
data sufficient to explain these phenomena; what has been advanced
may, perhaps, serve to elicit further information, by pointing out
the difficulties in which the question is involved, and showing
what interesting fields of discovery are still unexplored, and how
comprehensive and important are the objects that come within the scope
of geological investigation.[59]
[59] I would refer the student for a fuller consideration of the
phenomena thus briefly noticed, to the 6th edition of my Wonders of
Geology, pp. 669, 718, 731.
* * * * *
I will conclude this chapter with the following beautiful reflections
of Dr. Buckland on the origin and nature of Coal, and the changes it
undergoes when rendered subservient to the necessities and luxuries of
man.
"Few persons are aware of the remote and wonderful events in the
economy of our planet, and of the complicated applications of human
industry and science, which are involved in the production of the coal
that supplies with fuel the metropolis of England.
"The most early stage to which we can carry back its origin, was among
the swamps and forests of the primeval earth, where it flourished
in the form of gigantic Calamites, and stately _Lepidodendra_, and
_Sigillariæ_. From their native bed, these plants were transported
into some adjacent lake, or estuary, or sea. Here they floated on the
waters, until they sank saturated to the bottom, and being buried in
the detritus of adjacent lands, became transferred to a new estate
among the members of the mineral kingdom. A long interment followed,
during which a course of chemical changes, and new combinations of
their vegetable elements, converted them to the mineral condition of
coal. By the elevating force of subterranean agency, these beds of
coal have been uplifted from beneath the waters, to a new position in
the hills and mountains, where they are accessible to the industry of
man. From this fourth stage, coal has been removed by the labours of
the miner, assisted by the arts and sciences, that have co-operated to
produce the steam-engine, and the safety-lamp. Returned once more to
the light of day, and a second time committed to the waters, it has,
by the aid of navigation, been conveyed to the scene of its next and
most considerable change by fire; a change during which it becomes
subservient to the most important wants and conveniences of man. In
this seventh stage of its long eventful history, it seems, to the
vulgar eye, to undergo annihilation; its elements are, indeed, released
from the mineral combinations which they have maintained for ages, but
their apparent destruction is only the commencement of new successions
of change and of activity. Set free from their long imprisonment, they
return to their native atmosphere, from which they were absorbed by the
primeval vegetation of the earth. To-morrow they may contribute to the
substance of timber, in the trees of our existing forests; and having
for a while resumed their place in the living vegetable kingdom, may,
ere long, be applied a second time to the use and benefit of man. And
when decay or fire shall once more consign them to the earth, or to the
atmosphere, the same elements will enter on some further department of
their perpetual ministration in the economy of the material world."[60]
[60] Bd p. 481.
CHAPTER VI.
FOSSIL VEGETABLES.
In the present section of this work, I propose to explain the botanical
arrangement and nomenclature of fossil plants; and figure and describe
one or more species of the genera that are most likely to come
under the observation of the student, either in public or private
collections, or in the course of his researches in the field.
To determine the botanical relations of fossil leaves and stems,
reference must be had to works expressly devoted to the subject;
namely, the "_British Fossil Flora_," by Dr. Lindley and Mr. Hutton,
and the "_Histoire des Végétaux Fossiles_," by M. Adolphe Brongniart.
The classification of the last-named eminent botanist is here adopted,
as the most easy of application.
With regard to the nomenclature, it may be necessary to remark, that
when a fossil plant undoubtedly belongs to a recent genus, the usual
botanical name is employed: for example, _Equisetum Lyellii_; when the
fossil does not possess all the generic characters, yet is evidently
allied to a recent genus, the term _ites_ (from λιθος, _lithos_,
stone), is added--as _Equisetites_, _Palmacites_, &c.; and this
termination is invariably adopted by some authors. When the fossil
plant differs altogether from any known type, it is distinguished by
some arbitrary generic name, as _Bucklandia_, _Sigillaria_, &c.
There are also a few provisional genera for the reception of fossil
leaves, fruits, and stems, whose characters and relations are but
imperfectly known; as Carpolithes, Endogenites, &c. Upon these
principles the present arrangement has been founded: the progress of
discovery will, of course, be continually adding to the list, and the
classification require to be modified.
[Sidenote: FOSSIL CRYPTOGAMIA.]
The following account of the principal types of the ancient floras
whose relics are preserved in the mineral kingdom, though commencing
with those of the most simple structure, the _Cryptogamia_, and
advancing to the higher orders, is not strictly botanical; for it was
found convenient, in some instances, to notice certain species and
genera of different orders under the same head, from their occurrence
in the same geological formations.
It is estimated that not more than two thousand species of plants have
been discovered in a fossil state, while the known recent species
amount to upwards of eighty thousand.
Cellular Cryptogamia; Algæ.--The plants designated by botanists _Algæ_,
and commonly known as sea-weeds, lavers, and fresh-water mosses, are
of the most simple structure--mere aggregations of cells--but present
innumerable varieties of form and magnitude: many species are mere
vesicles of such minuteness as to be invisible to the unassisted eye,
except accumulated in countless myriads, when they appear as a green,
purple, or reddish, slime in the water; or as a film on wood or stone,
or on the ground, in damp situations; while others are tough branched
marine plants, many fathoms in length.
The Algæ form three principal groups: 1. the _jointless_, as the
Fuci, the Dulses, Tangles, and Lavers: 2. the _jointed_, which are
composed of thread-like articulated tubes; such are the fresh-water
Confervæ: 3. the _disjointed_, or Brittle-worts, so called from their
spontaneous self-division, which is in some kinds complete, in others
only partial; and these, by separating transversely, and leaving
each cell or frustule attached at the angles, produce those beautiful
chains of angular green transparent cases, so constantly seen under
the microscope when substances from fresh-water streams or lakes are
submitted to examination.
As many of these forms are endowed with spontaneous motion, and possess
other properties common to animal organization, it is not surprising
that their vegetable nature was doubted, and that even so profound
a naturalist as M. Ehrenberg placed them in the animal kingdom:
the greater number being comprised in his family of _Bacillariæ_,
were described in the former edition of this work, as Infusoria or
Animalcules; in conformity with the classification of the illustrious
microscopist, whose splendid works and indefatigable labours have so
greatly promoted the advancement of microscopical investigation.[61]
[61] The whole of the objects called _Infusoria_ in the first edition
of "The Medals of Creation" belong to various kinds of Diatomaceæ.
[Sidenote: FOSSIL DIATOMACEÆ.]
These minute vegetable organisms are placed by botanists in two
tribes, the _Diatomaceæ_ or the _Brittle-worts_, and the _Desmidieæ_.
The latter are exclusively inhabitants of fresh-water, while a large
proportion of the former are marine plants. Some naturalists (M.
Brébisson) restrict the name _Diatomaceæ_ to those species which
secrete siliceous envelopes; and that of _Desmidieæ_ to those whose
structures are not siliceous, and are reducible by heat to carbon. As
the durable parts of these plants alone concern the geologist, the name
_Diatomaceæ_ will be employed as a general term in reference to their
fossil remains.
These tribes of Algæ abound in every lake and stream of fresh-water,
in every pool or bay, and throughout the ocean from the equator to
the poles. Certain kinds of sea-weeds secrete carbonate of lime; but
the Diatomaceæ have the power of separating silex, or the earth of
flint, from the water, by some unknown process, and their tissues are
composed of pure quartz: hence, under the microscope, their remains,
consisting wholly of rock crystal, exhibit the most exquisite forms,
elaborately fretted and ornamented (see _Lign. 4_). After the death and
decomposition of these plants, their durable frustules or cases appear
as colourless discs, cups, spheres, shields, &c., and these accumulate
at the bottom of the water in such inconceivable numbers, as to form
strata of great thickness and extent. Slowly, imperceptibly, and
incessantly, are the vital energies of these atoms separating from the
element in which they live the most refractory and enduring of mineral
substances, silex, and elaborating it into imperishable structures, and
thus adding enormous contributions to the accumulations of detritus,
which make up the sedimentary rocks of the crust of the globe.
The extent of this infinitesimal flora throughout regions where no
other forms of vegetation are known, is strikingly demonstrated by the
observations of our eminent botanical traveller. Dr. Joseph Hooker, in
his account of the Antarctic regions.[62]
[62] "On the Botany of the South Polar Regions;" in Sir J. Ross's
Voyage of Discovery.
"Everywhere," Dr. Hooker states, "the waters and the ice alike abound
in these microscopic vegetables. Though too small to be visible to
the unassisted eye, their aggregated masses stained the iceberg and
pack-ice wherever the latter were washed by the sea, and imparted a
pale ochreous colour to the ice. From the south of the belt of ice
which encircles the globe, to the highest latitudes reached by man,
this vegetation is everywhere conspicuous, from the contrast between
its colour and that of the white snow and ice in which it is imbedded.
"In the 80° of south latitude all the surface ice carried along by
currents, and the sides of every berg, and the base of the great
Victoria barrier itself--a perpendicular wall of ice, from one to two
hundred feet above the sea level--were tinged brown from this cause, as
if the waters were charged with oxide of iron. The majority of these
plants consist of simple vegetable cells enclosed in indestructible
silex; and it is obvious that the death of such multitudes must form
sedimentary deposits of immense extent.
"The universal existence of such an invisible vegetation as that of the
Antarctic Ocean is a truly wonderful fact, and the more so from its
being unaccompanied by plants of a high order. This ocean swarms with
mollusca, and entomostracous crustaceans, small whales, and porpoises;
and the sea with penguins and seals, and the air with birds; the animal
kingdom is everywhere present, the larger creatures preying on the
smaller, and these again on those more minute; all living nature seems
to be carnivorous. This microscopic vegetation is the sole nutrition
of the herbivorous animals; and it may likewise serve to purify the
atmosphere, and thus execute in the Antarctic latitudes the office of
the trees and grasses of the temperate regions, and the broad foliage
of the palms of the tropics."
Dr. Hooker also remarks that the siliceous envelopes of the same kinds
of diatomaceæ now living in the waters of the South Polar Ocean, have
contributed in past ages to the formation of European strata; for the
tripoli and the phonolite stones of the Rhine, contain the siliceous
envelopes of identical species.
Such are the comments of one of our most distinguished botanists, on
the phenomena under review. The reader will perhaps ask, what then are
the essential characters which separate the animal from the vegetable
kingdom? To this question it is impossible to give a satisfactory
reply: perhaps the only distinction that will be generally admitted by
zoologists and botanists is the following:--_animals require organic
substances for their support; vegetables derive their sustenance from
inorganic matter_.
[Sidenote: RECENT DIATOMACEÆ.]
Recent Diatomaceæ. _Plate IV._--To familiarize the reader with
the nature of these vegetable organisms, a few recent species are
represented in Plate IV., coloured as they appear when alive, under the
microscope; the figures are magnified as expressed by the fractions.
_Xanthidium._ _Plate IV. figs. 1, 2, 3, 4, 5._--The case or frustule
of this genus consists of a hollow, siliceous globe, beset with
spines. The increase of the Xanthidia by self-division, produces the
double appearance in the figures, all of which are in the progress of
separation.[63]
[63] The organisms so abundant in the flint and chalk, and which were
referred by M. Ehrenberg to this genus, and consequently described
under the name of Xanthidia by myself and others, are certainly in
nowise related to the recent forms: they are flexible envelopes, and
probably belong to zoophytes; as will be shown in the sequel.
_Pyxidiculum._ _Plate IV. fig. 2._--The case is a little saucer-shaped
box, and is invested by a membrane.
_Bacillaria._ _Plate IV. fig. 6._--A simple siliceous frustule, of a
prismatic shape, forming a brilliant chain, which often appears in
zigzag, in consequence of incomplete self-division. An immense number
and variety of forms are placed in this family by Ehrenberg, with
a multitude of generic and specific names. The fresh-water species
inhabit every pond and lake, and the marine every sea. Fossil species
are equally abundant.
_Cocconeis._ _Plate IV. fig. 7._--This is a very elegant type; the
frustule consists of a simple siliceous case, with a central opening;
it never occurs in chains like the former. It has been found fossil
near Cassel.
_Navicula._ _Plate IV. figs. 8, 9, 14, 15._--The plants of this genus
are free, and float in the water apparently by the agency of cilia.
Their case is a boat-like envelope with six openings, composed of pure
silex, and in many species is exquisitely ornamented. Figs. 8 and 9.
show a living _Navicula_, viewed in front, and in profile: in _fig. 9_
are represented the currents produced when the body is moving through
the water; after Ehrenberg. Fossil _Naviculæ_ abound in many tertiary
strata.
_Galionella._ _Plate IV. figs. 10, 11._--These algæ are free, and the
frustules of a cylindrical, globular, or discoidal form; they occur in
chains, in consequence of the self-division being imperfect, and the
new individuals remaining attached to the old. The _Galionellæ_ are
most abundant and prolific, and inhabit every pool, stream, and lake:
fossil species occur in the Virginian marls, and other strata.
_Synhedra._ _Plate IV. fig. 12._--The frustules are siliceous, and of a
slender, elongated form. The plant is attached by the base (_fig. 12
a._) in youth, and afterwards becomes free. It is found fossil in the
Mountain-meal of Santa Flora, and many other deposits.
_Podosphenia._ _Plate IV. fig. 13._--The frustule is cruciform, or
wedge-shaped, and attached in youth by the small end, but afterwards
becomes free. These plants are often arranged in clusters, as in
the figure. M. Ehrenberg states that they inhabit the sea, and not
fresh-water; but I have found them in streams communicating with the
Thames. _Podospheniæ_ abound in the polishing slate of Bilin.
_Eunotia._ _Plate IV. figs. 16, 17._--The frustule is siliceous, and
either simple or bivalve; flat below, and convex, and often richly
dentated above. An empty case is shown _fig. 16_; and a group of living
_Eunotice_ attached to a stem of conferva, _fig. 17_. Several fossil
species have been discovered at Santa Flora.
That the general reader, whose attention is for the first time
directed to this subject, may be prepared for the enormous deposits
of fossil diatomaceæ that are found in some formations, I subjoin the
observations of Dr. Bailey on an elegant fragile species, which hangs
together in clusters, appearing like spiral chains, and is about 1/20
of a line in diameter; it is named _Meridion vernale_.
"This fresh-water plant is seen in immense quantities in the mountain
brooks around West Point, the bottoms of which are literally covered
in the first warm days of spring with a ferruginous-coloured mucous
matter, about a quarter of an inch thick, that, on examination by the
microscope, proves to be filled with millions and millions of these
exquisitely beautiful siliceous organisms. Every submerged stone, twig,
and spear of grass, is enveloped by them; and the waving plume-like
appearance of a filamentous body covered in this manner, is often
extremely elegant. Alcohol completely dissolves the endochrome (_soft
colouring matter_) of this species, and the frustules are left as
colourless as glass, and resist the action of fire."[64]
[64] Trans. Amer. Assoc. Geolog. 1843, p. 152.
The yellow or ochreous scum observable in ponds, ditches, and
stagnant pools, is an aggregation of diatomaceæ, whose frustules are
feriniginous, and of such extreme minuteness, that a billion of their
cases would not be more than a cubic inch in bulk.[65]
[65] Ehrenberg.
Fossil Diatomaceæ.--From this notice of a few recent types, we proceed
to the investigation of the fossil remains of this tribe of Algæ.
In peat-bogs and swamps, both of modern and ancient date, masses of
a white marly or siliceous paste (_hydrate of silica_), are often
observed, and these are found upon microscopical observation to
be wholly made up of the frustules of _Naviculæ_, _Bacillariæ_,
_Galionellæ_, &c., with an intermixture of the needle-like spicules of
fresh-water sponges. Many of the peat-bogs of Ireland contain layers of
a white earthy substance, which, when dry, is of the appearance and
consistence of friable chalk, and entirely consists of the siliceous
cases of various kinds of diatomaceæ.
[Illustration: Lign. 4. Siliceous Frustules of Diatomaceæ, and Spicules
of Spongillæ; from a deposit on the banks of the river Bann, Ireland.
(_Seen by transmitted light, and highly magnified._)]
[Sidenote: FOSSIL DIATOMACEÆ OF IRELAND.]
Fossil Diatomaceæ from Ireland, _Lign. 4._--Dr. Drummond describes
a bed of this kind near the base of the Mourne Mountains, in the
County of Down, Ireland. It consists of a very light white substance,
resembling in appearance carbonate of magnesia: it has a coarse and
somewhat fibrous fracture, and is easily reduced to powder. It is
almost entirely siliceous, and is composed of the cases of diatomaceæ
of the usual fresh-water species, without any admixture of inorganic
matter.[66]
[66] Mag. Nat. Hist. New Series, vol. iii. p. 353, July 1839.
On the banks of the river Bann, in the same county, there is an
extensive stratum of a similar earth, and which, from being in much
request for polishing plate, is locally known as Lord Roden's plate
powder. This earth is wholly made up of the siliceous frustules of many
kinds of this tribe of Algæ, and a few grains under the microscope
yield a great variety of exquisite forms: figures of several are
given in _Lign. 4_, from specimens of this earth, with which I was
favoured by the Countess of Caledon. They comprise two or three species
of Navicula, Galionella, Coscinodiscus, Gomphonema, Bacillaria,
Stauroneis, &c., and spicules or spines of fresh-water sponges.[67]
[67] The names of the usual kinds of Diatomaceous frustules may be
learnt by reference to Mr. Andrew Pritchard's abstract (with coloured
figures) of Ehrenberg's Infusoria. The splendid work of Mr. Ralfs, on
the British Desmidieæ, 1 vol. 4to, with coloured plates, is the best
guide for those who wish to study the recent plants.
Beds of siliceous marl--that is, of argillaceous earth combined with
a large amount of minute particles of silex, all of which prove to be
organisms when examined by a high magnifying power,--have been found in
numerous places not only in England, but all over the world, since M.
Ehrenberg first directed attention to their nature and origin.
Near Bryansford (Newcastle), Binstwick in Holderness, and in the Fens
of Lincolnshire and Cambridgeshire, extensive fresh-water microphytal
deposits have been discovered and examined.
From our Antipodes I have received many examples of these vegetable
earths. My eldest son, Mr. Walter Mantell, discovered an extensive bed
of white marl on the banks of the great brackish-water lake of Waihora,
in the middle island of New Zealand, consisting entirely of frustules
of Bacillariæ. From New Plymouth he obtained some new and exquisite
forms of Navicula, Stauroneis, &c.; ranges of low hillocks of sand,
of considerable extent, being made up of microphytes (_microscopic
plants_).[68]
[68] See a Memoir on the Geology and Fossil Remains of New Zealand,
from the researches of Walter Mantell, Esq.--_Geol. Journal_, vol. vi.
_pl._ 29.
Mr. Dean, of Clapham Common, informs me that a large quantity of white
earth sent from New Zealand as native magnesia, he found to consist
wholly of frustules of diatomaceæ, chiefly of _Galionellæ_. (See _Lign.
5._)
[Illustration: Lign. 5.
Fossil. Galiomellæ; _highly magnified_.]
In America, recent beds of this kind of great extent have been observed
and examined by that distinguished microscopist, Dr. Bailey, Professor
of Chemistry in the Military Academy at West Point: and the pages of
that excellent scientific periodical, Silliman's _American Journal of
Science_, are enriched with figures and descriptions of the microphytes
of which they are mainly composed.
But the Tertiary formations contain strata of this nature, which far
surpass in the abundance and variety of their organic contents, any
of the modern deposits we have noticed. The _Polierschiefer_, or
_polishing-slate_ of Bilin, is stated, by M. Ehrenberg, to form a
series of strata fourteen feet in thickness, entirely made up of the
siliceous shells of _Galionellæ_, of such extreme minuteness, that
a cubic inch of the stone contains forty-one thousand millions. The
_Berghmehl_ (_mountain-meal_, or _fossil farina_), of San Flora, in
Tuscany, is one mass of these organisms.
In Lapland a similar earth is met with, which, in times of scarcity, is
mixed by the inhabitants with the ground bark of trees, for food; some
of this earth was found to contain twenty different species of algæ.
In the district of Soos, near Egra, in Bohemia, a fine white infusorial
earth occurs, about three feet beneath the surface; this substance,
when dried, appears to the naked eve like pure magnesia, but under the
microscope is seen to be mainly constituted of elegant disciform cases
of a species of _Campilodiscus_, of which figures are given, _Lign.
111, figs. 1, 2_.
Some beds of porcelain-earth M. Ehrenberg found to be in a great
measure made up of concentric articulated rings, entire and in
fragments (see _Lign. 6_), which he believes to be bacillariæ.
[Illustration: Lign. 6 Organic Bodies in Porcelain Earth; _highly
magnified_.]
[Sidenote: FOSSIL DIATOMACEÆ OF VIRGINIA.]
Fossil Diatomaceæ of the Richmond-earth; Virginia.--The town of
Richmond, in Virginia, is built on strata of siliceous marl of great
extent, which earth; highly magnified. have a total thickness, beneath
and around the town, of more than twenty feet. These marls, whose
organic composition was first detected by Professor W. B. Rogers, are
referred by that eminent American geologist, to the older tertiary
(_eocene_, or _miocene_) formations. They occupy considerable
districts, spreading out into sterile tracts along the flanks of
the hills, their siliceous character rendering them unfavourable to
vegetation. The investigations of Dr. Bailey have shown that the
frustules so abundant in this earth, consist of several species of
Navicula (_Lign. 1, fig. 1, 1a_.), Galionella (_Lign. 1. fig. 3,
3a_.), _Actinocyclus_ (_Lign. 1, figs. 4, 5_), &c.
The most remarkable forms are disciform frustules, having their
surfaces elaborately ornamented with hexagonal spots disposed in
curves, and bearing some resemblance to the engine-turned case of a
watch. _Lign. 7, fig. 2_, is a small segment of a disc, very highly
magnified. These frustules vary in size from 1/100 to 1/1000 of an inch
in diameter; they are named _Coscinodiscus_ (_sieve-like disc_), and
there are several species: one less richly sculptured, _C. patina_, is
figured _Lign. 7, fig. 6_. Circular bodies, with five or six lines
radiating from the centre to the circumference, like the spokes of
a wheel, hence named _Actinocyclus_ (_Lign. 7, figs. 4, 5_), and
spicules of Sponges, are also abundant.
[Illustration: Lign. 7. Microphytes[69] from the Richmond-earth;
_highly magnified_.
_Tertiary. Virginia._
Fig. 1.--Navicula. 1_a_. Side view.
2.--Coscinodiscus radiatus; a portion of the circular shield.
3.--Galionella sulcata; the upper figure shows the transverse
face of one of the frustules.
3_a_.--Three united cells viewed laterally.
4, 5.--Actinocyclus. Two species.
6.--Coscinodiscus patina; transverse view.
6_a_. Lateral view.
]
[69] As the term _Infusorial-earth_ must be abandoned, it will be
convenient to substitute a name simply expressive of the nature of
the most abundant organisms that enter into the composition of these
deposits: that of _Microphyta_, or _Microphytes_, (from μικρος,
_mikros_, small, and φυτον, _phyton_, a plant), signifying very
minute vegetables, may perhaps be admissible: in this sense the word
microphytal is employed in these pages.
When a few grains of the marl are prepared, and mounted on a glass,
almost all these varieties will be manifest, so largely is this earth
composed of organic structures; in fact, very few inorganic particles
are intermixed, the merest pellicle left by the evaporation of a drop
of water in which some of the marl has been mixed, teeming with the
most beautiful structures.
At Petersburg, in Virginia, a sandy marl occurs, interstratified with
deposits which, from their shells, are referred to the older tertiary
formations. Probably this marl is a continuation of that of Richmond,
but it is full of many new forms, associated with those common in the
earth of the latter locality.[70]
[70] Dr. Bailey, with great liberality, has so amply supplied myself
and other observers with specimens of these deposits for examination,
that the fossils above described are familiar to all British
microscopists. Figures of many of those organisms are given in the
American Journal of Science.
It is an interesting fact, (first observed by Mr. Hamlin Lee,) that the
common Scallop (_Pecten maximus_), as well as the Barnacle (_Balanus_),
feed on diatomaceæ, and their stomachs generally contain numerous cases
of Coscinodisci, Dichtyochi, Actinocycli, &c.: a slide prepared and
mounted with the contents of the stomachs of these mollusks, presents
an assemblage of forms identical with those found in the tertiary
earths of Virginia.[71]
[71] See my "Thoughts on Animalcules," p. 103.
In the mud of the quicksands on the shore at Brighton, Mr. Reginald
Mantell found recent Coscinodisci, &c. associated with fossil
polythalamia that had been washed out of the chalk, and precipitated
with the frustules of the recent diatomaceæ, into the sediments now in
progress.
The prevalence of marine and fresh-water forms in the same deposit
is not unusual; and the remarks of Dr. Bailey on this fact are so
pertinent, that I insert them, as a salutary caution against hasty
generalizations on subjects connected with these investigations.
After describing a species of Galionella (_G. moniliformis_), as an
inhabitant only of salt and brackish water, and stating that he had
also found it sixty miles up the Hudson River, near West Point, Dr.
Bailey observes--"The Fauna and Flora of the Hudson at this place
would, if in a fossil state, be rather puzzling to the geologist, on
account of the singular mixture of marine and fluviatile species. While
_Valisneria_ and _Potamogeton_ (two common fresh-water plants), grow
in such vast quantities, in some places, as to prevent the passage
of a boat, and the shore is strewn with fluviatile shells (such as
Planorbis, Physa, &c.) in a living state, yet the above plants are
entangled with Algæ (sea-weeds), and marine parasitic zoophytes; while
the rocks below low-water mark are covered with Balani (_barnacles_)
and minute corallines, and the marine Flora is represented by vast
quantities of very elegant sea plants."[72]
[72] American Journal of Science, vol. x. p. 41.
* * * * *
I must here close this extended notice of the fossil remains of a class
of vegetable organisms, which, though for the most part invisible
to the unassisted eye as individual forms, constitute by their
inconceivable multitudes an important element in the formation of
sedimentary deposits. The fact of their having been formerly treated
of as animalcules, and generally regarded as belonging to the animal
kingdom, rendered a full consideration of the phenomena necessary,
in order to place the subject before the reader in a clear and
comprehensive point of view.[73]
[73] As both the recent and fossil frustules of Diatomaceæ are
beautiful objects for the microscope and polariscope, they are in much
request. Specimens mounted on glass slides may be had of Mr. Topping,
and Mr. Poulton. See Appendix.
Confervites.--The cellular aquatic plants named Confervæ are sometimes
found in transparent quartz pebbles, and in chalk, appearing as
delicate simple or branched filaments, which, by the aid of the
microscope, are seen to be articulated. Seven species are described
by authors, but the vegetable nature of some of these is doubtful. A
beautiful species in Chalk, first noticed by the late Samuel Woodward,
Esq. (author of the Geology of Norfolk), is here figured.
[Illustration: Lign. 8. Confervites Woodwardii; _nat._
_Chalk. Norfolk._]
[Sidenote: FOSSIL FUCOIDS.]
Fossil Fucoids.--Of the tribe of Algæ which comprises the sea-weeds
that are not articulated, many fossil species occur in very ancient,
as well as in modern, fossiliferous deposits. In the Lower Silurian
rocks of North America, beds of limestone of great extent are full of
a large digitated Fucus (_Fucoides Alleghaniensis_).[74] The Firestone
or Malm-rock of Bignor in Sussex abounds in a ramose variety (_Fucoides
Targionii_, _Vég. Foss._ p. 56), of which specimens are figured in the
vignette of this volume, and in _Lign. 9._
[74] Figured and described in Dr. Harlan's Medical and Physical
Researches: Philadelphia, 1835, p. 393.
Chondrites.--These fossil algæ approach nearest to the living species
of _Chondrus_ (hence the name of the genus). The frond is thick,
branched, dichotomous, with cylindrical or claviform divisions, with
a smooth surface and without tubercles. The substance of the Bignor
fossils is a white friable earth, which strikingly contrasts with
the dark grey malm-rock that forms the matrix. As the Sussex Chalk
Chondrites appear to be distinct from the Tertiary species named by M.
Brongniart _C. Targionii_, I have, at the suggestion of Mr. Morris,
substituted _C. Bignoriensis_, to indicate the locality in Sussex in
which I discovered it forty years since. In the chalk-flints ramose
fuci occasionally occur, but not in a state of preservation that admits
of the determination of the forms of the originals.
[Illustration: Lign. 9.
Chondrites Bignoriensis; _nat._
_Malm-rock. Bignor, Sussex._]
The tertiary marls and limestones of Monte Bolca yield several
beautiful species of Algæ, one of which is figured in _Lign. 10_. It is
referred to the fossil genus _Delesserites_ (Sternberg), which includes
those algæ that have thin, and flat or undulated, smooth, membranous
fronds, with a median rib.
Of the little plants comprised in the class of cellular cryptogamia,
which have stems, leaves, and fructification, but no true vessels, two
or three species of Moss and Liverwort have been met with in tertiary
strata. Mosses as well as Fuci are occasionally imbedded in quartz
pebbles, in which they appear of their natural colour, and apparently
floating in the transparent medium. A beautiful green moss, with a
Conferva twined round its base, is figured _Lign. 11_ , p. 104, from a
specimen described by the late Dr. Macculloch. It is supposed to be
related to _Hypnum_ (_Geol. Trans._ vol. ii.).
[Sidenote: MOCHA-STONES.]
Moss-agates and Mocha-stones.--The beautiful siliceous pebbles called
Moss-agates, and Mocha-stones, will so often come under the notice
of the collector, that, although but extremely few, if any, of these
objects contain organic remains, the arborescent substances they
inclose being merely metallic oxides, a few remarks on their nature
may be expected. The late Dr. Macculloch paid considerable attention
to the investigation of these bodies, and believed that some of
the objects imbedded in the pure and compact quartz were really of
vegetable or animal origin; the specimen figured _Lign. 11_ is of this
kind; the fossils being apparently cellular cryptogamous plants. In
_Geol. Trans_, vol. ii., other examples are figured and described by
the same sagacious observer. Mr. Bowerbank is of opinion that spongeous
structure enters into the composition of almost all the moss-agates,
and I have no doubt that in some instances such organisms are present:
but in by far the greater number of agates and mocha-stones the
inclosed bodies are mere crystallizations; they are arborescent or
dendritical oxides of manganese, copper, chlorite, iron, &c.
[Illustration: Lign. 10 Delesserites (Fucoides) Lamourouxii.
_Monte Bolca._ (_Vég. Foss. Br._)]
[Illustration: Lign. 11.
Moss and Conferva, in transparent quartz, × 3.]
M. Brongniart, who carefully examined a great number of agates and
pebbles, with the view of determining if vegetable substances were
ever imbedded in them, could not detect a single instance in which
the apparent mosses, confervæ, or algæ, were organic; in every case
the mineral origin of the pseudo-vegetation was, in his opinion,
unequivocal. Some of the beautiful green arborescent bodies in quartz
pebbles, even under the microscope, present so close a resemblance to
confervæ and mosses, that it is difficult to persuade oneself they are
not vegetable structures; but the observations of M. Brongniart appear
to me conclusive as to their mineral nature.[75] With the exception of
three or four species of _Jungermannia_, and four or five of _Muscites_
in Amber, M. Brongniart states that he knows but one true fossil plant
of the family of Mosses; the _Muscites Tournalii_ from the fresh-water
tertiary deposits of Armissan.
[75] See Histoire des Végétaux Fossiles, pp. 29-34.
Vascular, or Acrogenous Cryptogamia.--These plants, as the name
implies, possess a more complicated structure than the preceding,
having vascular tissue as varied as in the phanerogamia.
Equisetaceæ.--The common species of Equisetum, or Marestail, is a plant
that grows in marshy tracts, and on the banks of ditches and rivers; it
has a jointed stalk, garnished with elegant sheaths which embrace the
stem, and verticillate linear leaves: it attains a height of two feet,
and is half an inch in diameter. In the fossil state there are many
plants allied to the Equisetum, but only a few that are generically the
same.
[Illustration: Lign. 12. Equisetum Lyellii.
_Wealden. Pounceford._ _nat._
Fig. 1.--A stem, having two sheaths, and a bud at the lowermost joint.
2.--Stem of a young plant, with sheaths, preserved in pyrites.
3.--Stem, with the cryptogamous head or upper end.
]
[Sidenote: EQUISETITES.]
Equisetum Lyellii, _Lign. 12_.--A species which I discovered in Wealden
limestone, at Pounceford (_Geol. S. E._ p. 245), must have closely
resembled the _Equisetum fluviatile_: it has an articulated cylindrical
stem, and regularly dentated sheaths, embracing the stem at the joints.
A transverse slice of the stem exhibits under the microscope a cellular
structure filled with calc-spar, and forms a beautiful object when
viewed with the polarizing apparatus. This plant occurs in many
localities of the Wealden in Sussex and Kent; from the railway cuttings
near Tonbridge, I collected several fine specimens; it is met with also
in the cliffs near Hastings.
Equisetites columnaris. _Lign. 13_.--A gigantic species of Equisetum
abounds in the strata of the lower division of the Oolitic or Jurassic
formation of Yorkshire, and many fine specimens have been collected,
especially from the vicinity of Whitby. In the sandstone of the
Inferior Oolite of the Cleveland Hills, Yorkshire, numerous stems
of this colossal marestail have been observed standing erect, as if
occupying the position in which they grew; the same fact was also
discovered at Carlton Bank, near Stokesly, forty miles from the coast.
In both localities fossil shells of fresh-water mussels (_Uniones_)
were associated with the vegetable remains.
[Illustration: Lign. 13. Equisetites columnaris.
(Ad. Brongn. Pl. 13.)
_Lower Oolite. Whitby._
Fig. 1.--Portion of a stem, showing two articulations, and an
intermediate constriction. 1/3 _nat._
2.--A few of the denticulations produced by the sheath, _nat._
]
This plant is a true equisetum, differing chiefly from existing species
in its gigantic size and arborescent character. The sheaths surrounding
the stem, and the verticillate linear leaves, are preserved in some
examples: and in all, the furrows left by the imprints of the sheaths
are more or less strongly impressed. The stem is not channelled
throughout, as in _Calamites_, the carboniferous plant whose stems at
first sight might be mistaken for those of Equisetites, but which are
entirely distinct, as will be explained hereafter. The Equisetites
columnaris is peculiar to the Oolite; it does not occur in the
coal-measures. Specimens have been discovered which indicate a height
of twenty feet, and a diameter of several inches.[76]
[76] See Hist. Vég. Fossiles, p. 115.
A small species of Equisetum (_Eq. Brodiei_[77]) occurs in
the insectiferous limestone of the lower Lias, at Strensham,
Worcestershire, associated with the foliage of fresh-water endogenous
plants resembling the _Potamogeton_, or pond-weed, and of supposed
dicotyledonous vegetables.
[77] Prof. Buckman, in Geol. Journal, vol. vi. p. 413.
[Illustration: Lign. 14. Calamites decoratus.
1/3 _nat._
(Ad. Brongniart. Pl. 14.)
_Coal Formation. Yorkshire._
Fig. 1.--Part of a stem, showing the tubercles for the attachment
of leaves.
2.--A portion of the same on a larger scale.
]
[Sidenote: CALAMITES.]
Calamites. _Lign. 14, 15_.--Stem articulated, regularly furrowed
longitudinally, the articulations naked, or studded with tubercles.
The plants of this genus were supposed to be related to the marestail,
but to differ in the absence of the encircling sheaths, and in being
uniformly striated; but an examination of specimens in a better state
of preservation than those previously known, shows their affinity to
the gymnosperms. Some of the species are of a gigantic size, being from
one to three feet in diameter, and from thirty to forty feet in height.
Calamites abound in the coal formation, and must have constituted an
important feature in the forests of the carboniferous period; they
occur also in more ancient deposits, and some species belong to the
earliest terrestrial Flora of which any vestiges are known. In most
instances when specimens are found lying in the same plane with the
strata, they are pressed flat, but those occurring in a vertical
position retain their natural cylindrical form. An outer crust or
cylinder of coal generally invests the stem, but traces of the internal
structure are rarely preserved.
The Calamite consists of a large central column of tissue, surrounded
by a ligneous cylinder. The central part has in most instances perished
after the death of the plant, and the cavity thus left been filled
up with mineral matter. As the hollow ligneous zone is almost always
carbonized, and very friable, it is seldom attached to the cast, and
consequently the surface of the latter is generally jointed and ribbed.
The true external surface of the cortical investment is marked with
longitudinal striæ, without any indications of joints or constrictions;
but the position of the original articulations is indicated in some
specimens by the _presence of small verticillate scars, to which leaves
were appended_[78] as in the example figured by M. Brongniart, of which
_Lign. 14, fig. 1_, is a reduced figure.
[78] See Mr. Dawes, "On the Structure of Calamites," Proc. Geol. Soc,
1851, vol. vii. p. 197.
[Illustration: Lign. 15. Calamites, in Coal Shale.
Fig. 1.--Calamites radiatus, with the remains of one of the
sheaths.--1/2 _nat._
2.--Stem, with remains of roots.--1/2 _nat._
3.--Calamites approximatus, showing the curved lower end of the
plant.[79]--1/5 _nat._
]
[79] This specimen has been inadvertently drawn with the base uppermost.
The stellate appearance on the upper part of the stem figured in
_Lign. 15, fig. 1_, is produced by the zone of leaves which
surrounded the joint: this character is entirely distinct from the
sheath of the Equisetum shown in _Lign. 12_. This specimen points out
the importance of carefully examining and preserving the stone around
fossil stems; had this precaution been lost sight of in this instance,
no knowledge would have been obtained of this important botanical
character. It is rarely that any traces of the roots remain; the fossil
figured (_fig. 2_) is from the _Foss. Flor._ A beautiful example of the
foliage of a species of Calamites is represented in _Lign. 59, fig.
2_.
Upright stems of Calamites occur in the Coal formation near Pictou,
in North America; and in one example a group of ten or twelve stems,
covering an area of two square feet, sprung from one root.[80]
[80] Dawson, Geol. Proc. vol. vii. p. 195. See Sir C. Lyell's Travels
in North America, vol. ii. p. 195.
* * * * *
[Sidenote: FOSSIL FERNS.]
Filicites, or Ferns.
We now arrive at the consideration of one of the most interesting
families of the vascular cryptogamia that adorned the Flora of the
ancient world, and the living species of which impart beauty and
elegance to the scenery of the countries where they prevail. The most
essential character of these vegetables, is that of developing their
fructification on the leaves; a fact familiar to every one who has
even but cursorily examined the Polypody growing on our walls, or the
Brake of our hedge-rows and commons. The largest species of British
ferns scarcely exceed four or five feet in height; but the arborescent
or tree-ferns, of warm climates, attain an altitude of from thirty to
forty feet. There is too this peculiarity in the arborescent forms,
that while in our indigenous species the leaves surround the stem, and
incline towards the upper part of the plant, the foliage of the former
bends downwards, and spreads out from the crown, or summit, into an
elegant canopy.
[Illustration: Lign. 16. Pecopteris Sillimani; _nat._
_Coal Shale. Ohio._
_a._ The Stem.
_b._ Leaf-stalk, or petiole.
_c._ Leaf, or frond, which is bipinnate.
_d._ _e._ Leaflets, or pinnæ; the upper, _d_, are entire;
the lower, _e_, are pinnatifid.
_f._ The pinnules, lobes, or segments.
_g._ The midrib, or median vein.
_h._ The veins. The veins are introduced in the leaflets,
_d_; but in the lower ones, _e_, the midribs
only are marked.
]
The leaves of our branched ferns are persistent, and when shed, the
markings left by their attachment to the stalk are soon obliterated. In
the arborescent ferns, on the contrary, the petioles become detached
from their bases, and fall entire, leaving scars or cicatrices on
the stem; and these impressions are so regularly and symmetrically
disposed, as to afford characters by which the trunks may be
distinguished from those of other trees. The stems of the tree-ferns
are therefore easily recognized in a fossil state externally, by their
cylindrical forms without ramification, and by the regular disposition
and peculiar character of the scars left by the separation of the
petioles; and, internally by that peculiar zone, formed of bundles
of ligneous tissue inclosed in sheaths, which encircles the central
axis, as shown in the transverse sections in _Lign. 2_, _ante_, p.
62. The leaves may be identified by the form of their segments, which
are disposed with remarkable regularity, and have a peculiar mode of
subdivision; and above all, by the delicacy, evenness, and distribution
of the veins. There are upwards of two thousand species of living
ferns, and in the fossil kingdom the number is considerable; more than
two hundred have been collected from the carboniferous formation. The
recent tree-ferns are confined almost exclusively to the equinoctial
regions; humidity and heat being the conditions most favourable to
their development (_Vég. Foss._ p. 141. _Bd._ p. 461. _Wond._ p. 727).
From the elegance and diversity of form of their foliage, fossil ferns
are the most remarkable and attractive vegetable remains in the ancient
strata. The greater number are from the coal deposits, the fern-leaves
generally occurring in the schists or shales that form the roof of the
beds of coal. Many of the strata are made up of carbonized fern-leaves
and stems closely pressed together. The roof of a coal-mine, when
newly exposed, often presents a most interesting appearance, from the
abundance and variety of leaves, branches, and stems, that occur either
in relief, or impressed on the dark glossy surface. The specimens
selected for illustration exhibit the principal modes of venation on
which the genera are founded.
* * * * *
The fossil genera have been established by M. Ad. Brongniart, from
the form of the leaves and the characters of their venation; that is,
the distribution of the vessels. In the following descriptions some
botanical phrases are necessarily employed; a few terms of frequent
occurrence are explained in _Lign. 16_.
Pachypteris[81] (_thick-fern_). _Lign. 17._--In this genus from the
lower Oolite, the fronds are pinnated, or bipinnated, the leaflets
entire, without visible veins, having but a single midrib, and
contracted at the base. The absence of veins, and the leaflets not
being lobed, are the essential generic distinctions.
[81] The names of the genera are derived from _pteris_, fern, to which
prefixed a term indicative of the peculiar characters.
[Illustration: Lign. 17. Pachypteris lanceolata.
_Inferior Oolite. Whitby._]
[Illustration: Lign. 18. Sphenopteris elegans
_Coal-shale, Waldenburg, Silesia._]
[Sidenote: FOSSIL FERNS. SPHENOPTERIS.]
Sphenopteris (_wedge-leaf_). _Lign. 18_.--The leaves are twice or
thrice pinnated, the leaflets wedge-shaped, contracted or narrowest
at their base, and more or less deeply lobed: the lobes divergent and
palmated: the veins radiating from the base.
The ferns of this genus are extremely elegant, and comprise upwards of
forty species. A beautiful Sphenopteris (_S. affinis_, _Wond._ p. 716,)
occurs abundantly in the fresh-water carboniferous strata at Burdie
House, near Edinburgh;[82] another elegant form, in coal-shale, is
represented in _Lign. 18_.
[82] See Dr. Hibbert's Memoir on the Strata and Fossils of Burdie
House. 4to. 1835.
[Illustration: Lign. 19. Sphenopteris nephrocarpa.
_Inferior Oolite, Scarborough._
A magnified vein of a leaflet, showing the fructification at the
extremities of the lobes, × two diameters.]
It is so rarely that the fructification of any species of Sphenopteris
is preserved in a fossil state that I am induced to figure a leaflet
of a remarkable plant, of this genus from the fluvio-marine oolitic
deposits of Scarborough. _Lign. 19_ is copied from the lithograph
accompanying a notice of some rare plants from that locality, by the
eminent botanist, C. J. F. Bunbury, Esq.[83]
[83] Geol. Journal, vol. vii. p. 179, pl. xii.
This fossil fern closely resembles certain species of _Dicksonia_
(natives of New Granada). Each segment of the leaflet or pinnate
is dilated at the apex into a reniform _indusium_; no capsules are
visible, the fructification being, probably, in a young state.
[Illustration: Lign. 20. Sphenopteris Mantelli; _nat._ _Wealden,
Tilgate Forest._]
In the Wealden deposits, both of England and Germany, several species
of Sphenopteris abound; one of which (_Foss. Tilg. For._ 1827), often
occurs in the calciferous grit of Tilgate Forest, in a beautiful state
of preservation: a small branch is figured in _Lign. 20_. This species
is characterized by its slender and minutely divided wedge-shaped
leaflets. The Sphenopteris Mantelli did not attain a considerable size;
the largest stem I have seen indicated a plant of five or six feet in
height. This Sphenopteris is sometimes associated with the remains of a
beautiful plant of the genus _Alethoptris_,[84] the leaflets of which,
in some examples, bear the fructification. (_Wond._ p. 394, _Lign._ 89.)
[84] _Alethoptris elegans_ of Dr. Dunker. Mon. Norddeutschen Weald, pl.
vii. _fig. 7_.
[Illustration: Lign. 21. Cyclopteris trichomanoides; _a single
leaflet_; _nat._
_Oolite, near Scarborough._]
Cyclopteris (_round-leaf_). _Lign. 21._--The frond is simple and
entire, or but slightly lobed at the margin, and generally orbicular,
or kidney-shaped: there is no midrib; the veins are numerous, equal,
and dichotomous, or forked, and radiate from the base. The form and
disposition of the veins resemble those of some living species of fern;
the absence of a median rib, or vein, is the most striking character
of this genus. The fructification is supposed to have been marginal.
[Sidenote: FOSSIL FERNS. NEUROPTERIS.]
Neuropteris (_nerved-leaf_). _Lign. 22._--The fronds are pinnate or
bipinnate; the leaflets more or less ovate or cordiform and entire,
adhering to the rachis by their centre only; veins very fine, arched,
rising obliquely from the base of the leaflet; the midrib does not
extend' to the apex of the leaflets, but terminates by subdividing into
veins.
[Illustration: Lign. 22. Neuropteris acuminata; _nat._
_In Coal-shale, Yorkshire._]
This is a very numerous genus, comprising thirty or more species, which
are principally found in the coal-shale. Some of these plants bear
a general resemblance to the _Osmunda regalis_, but differ in their
essential characters; their leaflets often form the nuclei of ironstone
nodules.
Glossopteris (_tongue-leaf_). _Lign. 23._--Leaves simple,
sub-lanceolate, gradually contracting towards the base; midrib thick at
the base, and vanishing towards the apex of the leaf; veins very fine,
curved, oblique, frequently dichotomous, sometimes reticulated, or
anastomosing at their base. The plants of this genus resemble the ferns
with simple leaves. A few species only are known; of these, two are
from the coal-shale, one from the Lias, and one from the oolite.
[Illustration: Lign. 23. Glossopteris Phillipsii; _nat._
_Oolite, Scarborough._]
[Illustration: Lign. 24. Odontopteris Schlotheimii; _nat._
_Coal-shale of Saxony._]
Odontopteris (_tooth-leaf_). _Lign. 24._--Leaf bipinnate, the leaflets
adhering to the rachis or stalk by their whole base, which is not
contracted; the veins equal, simple, dichotomous, arising side by side
from the base of the leaflet; no distinct midrib. In their general
aspect these plants resemble some South American species of Osmunda.
Five species only are known, all of which belong to the most ancient
coal strata.
Anomopteris (_anomalous fern_--so named because the plants differ from
all recent and fossil ferns). _Lign. 25._--Leaves deeply pinnated;
leaflets very long, entire, linear, traversed by a distinct midrib,
equal throughout; secondary veins simple, perpendicular to the median
vein, swollen at their free extremities, and not extending to the
margin of the leaflet. But one species is known. These leaves are of
great size, and doubtless belonged to some arborescent fern; in several
examples the fructification is preserved. My collection contained a
splendid specimen from near Strasburgh, presented by the late M. Voltz,
which is now in the British Museum.[85]
[85] Petrifactions, p. 32.
[Illustration: Lign. 25. Anomopteris Mougeotii; _nat._
_New Red Sandstone; Sultz-les-Bains, near Strasburgh._
Fig. 1.--Three leaflets of a very large frond.
2.--A portion magnified to show the fructification.
]
[Sidenote: FOSSIL FERNS. TŒNIOPTERIS.]
Tœniopteris (_wreathed fern_). _Lign. 26._--Leaves simple,
entire, straight, with parallel margins, traversed by a strong
midrib, which extends to the apex; secondary veins, simple
or bifurcated at their base, and almost perpendicular to the
median vein. These ferns are related to certain species
of Polypodium. Three species are known; two from the
Oolite, and one from a tertiary deposit. The specimen
figured is a fragment.
[Illustration: Lign. 26. Tœniopteris latifolia; _fragment of a
frond; nat._
_Stonesfield Slate._]
[Illustration: Lign. 27.
Fig. 1.--Pecopteris Murrayana; a pinnule with the fructification;
_magnified._ _Inf. Oolite, Scarborough._
2.--Pecopteris lonchitica. _Coal-shale, France._
]
Pecopteris (_embroidered fern_). _Lign. 27._--Leaves once, twice, or
thrice pinnated: leaflets adhering by their whole base to the rachis,
rarely by the centre only; traversed by a strong midrib, which extends
to the apex; veins simple, or once or twice dichotomous, proceeding
almost at right angles from the median vein.
This genus embraces a very large proportion of the ferns which have
contributed to the formation of the coal, and whose leaves and
stems are preserved in the associated strata. The originals of many
species were undoubtedly arborescent, and attained a large size;
some leaves four feet wide, and of a proportionate length, have been
observed. More than one hundred species are determined. An American
species (_Pecopteris Sillimani_) is figured in illustration of
certain botanical terms, _Lign. 16_, _ante_, p. 110. Several species
of Pecopteris occur in the fluvio-marine oolitic deposits near
Scarborough, and leaves in fructification are not uncommon: _fig. 1,
Lign. 27_, represents a leaflet slightly magnified.
[Illustration: Lign. 28. Lonchopteris Mantelli.
_Wealden, Tilgate Forest._
Fig. 1 and 2.--Leaflets magnified, to show the reticulated venation.
3.--A fragment of a frond; _nat._
]
[Sidenote: FOSSIL FERNS. LONCHOPTERIS.]
Lonchopteris (_spear-leafed._) _Lign. 28._--Leaves many times pinnated;
leaflets more or less adherent to each other at their base, traversed
by a midrib; secondary veins reticulated.
The three known species which compose this genus resemble the living
ferns of the genera Lonchitis, Woodwardia, &c. Two have been found in
the coal-measures, and one species in the Wealden formation of England
and Germany (_Foss. Tilg. For._ pl. iii.) This last appears to have
been a delicate plant; for though fragments are very common in the
micaceous grits and clays, any considerable portion of a leaf is of
rare occurrence. M. Graves found the same fern near Beauvais in France,
in strata, which, from the presence of the fresh-water limestone called
Sussex marble, are supposed to be referable to the Wealden epoch. This
Lonchopteris is widely spread through the Wealden; and occurs also in
the Greensand. Mr. Morris first observed it in the iron-sandstone of
Shanklin Chine.[86]
[86] Geol. I. of W. 2d _Ed._ p. 230.
[Illustration: Lign. 29.
Fig. 1.--Phlebopteris[87] Phillipsii. _Oolite, Scorborough._
2.--Phlebopteris propinqua, _showing fructification_.
]
[87] Comptopteris of M. Ad. Brongniart.
Phlebopteris (_veined-leaf_). _Lign. 29._--Leaves pinnated; leaflets
with the margin entire, or crenulated, the midrib strong; secondary
veins anastomosing by arches, with large angular spaces, often
unequally disposed; the finer veins are simple or divided; the apex
sometimes free. The fructification is punctiform, and placed at the
apices of the veins.
The foliage of these remarkable ferns has been mistaken for the leaves
of dicotyledonous plants; but M. Brongniart has demonstrated that they
belong to the present family. Six species have been found in the Oolite
and Lias.
[Illustration: Lign. 30. Clathropteris meniscoides.
_Portion of a leaflet: the original 1-1/2 ft. long._
_Wealden? Scania._]
[Sidenote: FOSSIL FERNS. CLATHROPTERIS.]
Clathropteris (_latticed-leaf_). _Lign. 30._--Leaf deeply pinnatifid;
leaflets elongated, traversed by a strong midrib extending to the apex;
secondary veins numerous, simple, parallel, almost perpendicular to the
midrib, united by transverse branches, which, with the finer veins,
produce on the surface of the leaf a net-work of quadrangular meshes.
This genus was instituted by M. Brongniart, for the reception of
some very large fern-leaves from the shale of Hoer, in Scania,
which resemble in structure the foliage of the recent _Polypodium
quercifolium_, a native of the East Indies, and the Moluccas. One leaf
was four feet wide, and the leaflets, though imperfect, were eighteen
inches long.[88]
[88] Hoer is a little village, situated nearly in the centre of
Scania, a province in the southern extremity of Sweden. The Chalk
formation appears in several parts of this district, and Carboniferous
strata at Hoeganes. To the west of Hoer, there is a range of hills,
composed of ferruginous grits, micaceous sandstones, clays, and beds
of quartzose conglomerate. It is in these strata that the ferns and
other terrestrial plants occur, and no animal remains whatever have
been found in them; their geological position appears to be between
the Chalk and the Coal, but on this point nothing positive is known.
The general analogy of the plants with the group forming the Flora
of the Wealden, led M. Brongniart to suppose that the deposits in
question belong to that formation; and M. Nillson, of Lund, who
examined my collection at Brighton, recognized, among some undescribed
plants from Tilgate Forest, forms that he had collected from Hoer. See
"_Observations sur les Végétaux Fossiles renfermés dans les Grès de
Hoer en Scanie: par M. Ad. Brongniart._" _Ann. Sc. Nat._ 1825.
Many other genera of fossil ferns have been established from the form
and venation of the leaves, and are described in _Brit. Foss. Flor._,
and other British and foreign works.
Stems of arborescent Ferns.--Notwithstanding the profusion with which
the foliage of many kinds of ferns is distributed throughout the coal
formation, the undoubted stems of plants of this family are rarely
met with; for the numerous tribe called Sigillariæ is now removed
altogether from this class. It may, however, admit of question whether
much of the foliage which, from the analogy of structure, has been
referred to ferns, may not have belonged to those trees; for as in the
animal kingdom, so in the vegetable, distinct types of living organisms
are often found blended in the lost races; and as the stems of recent
tree-ferns are even more durable than their leaves, it seems impossible
to account for their absence in strata, that inclose entire layers of
the foliage matted together. A few fossils, supposed to possess the
essential characters of recent fern-stems, have been discovered, and
arranged under the following genus.
[Sidenote: FOSSIL FERN-STEMS.]
Caulopteris (_fern-stem_). _Lign. 31._--Stems not channelled, marked
with discoidal, oblong, or ovate scars, arranged longitudinally;
vascular cicatrices numerous.
[Illustration: Lign. 31. Caulopteris macrodiscus. _Coal._]
The fragment of stem here figured, resembles the trunks of some recent
tree-ferns in its proportions, and in the number, disposition, and
size, of the scars of the leaf-stalks; but these markings differ in
their more lanceolate form, and pointed terminations, and in their
peculiarly striated surface, from those of any known existing species.
Psarolites (_Silicified Fern-Stems_).--In the New Red sandstone, near
Hillersdorf, in the neighbourhood of Chemnitz, in Saxony, silicified
stems, apparently of tree-ferns, occur in great numbers. They are
remarkably beautiful, and the organization of the original is so well
preserved by the silex, that slices, examined by the microscope,
display the peculiar structure almost as perfectly as if the plants
were recent: transverse sections exhibit the arched bundles of vascular
fibres which compose the ligneous cylinder, surrounded by the cellular
tissue. From the stellated markings produced by sections of the vessels
that compose the tissues, and which are visible to the naked eye,
these fossils have obtained the popular name of _Staaren-stein_, or
Star-stone. The external surface of the specimens I have examined has a
ligneous structure, and is of a dark reddish brown colour; internally
the stems are of a dull red, mottled with various tints of blue and
yellow, from the infiltrated chalcedony with which the vessels are
permeated.[89]
[89] See Pict. Atlas (pl. viii.) for coloured figures; and Org. Rem.
vol. L plate viii. _figs._ 1-7. The reader will be amused by the
perusal of the ingenious but unsuccessful attempt of the excellent
author, Mr. Parkinson, to elucidate their nature. I have still a
specimen which he presented to me more than thirty-five years since, as
one of the most curious and perplexing fossils that had ever come under
his notice.
An excellent work ("_Dendrolithen_") on these fossils, in which thirty
species are described, has been published at Dresden by M. Cotta; who
arranges them under the genus _Psaronius_ or _Psarolites_. The stem is
composed of two distinct parts; an outer zone, consisting of a great
number of nearly cylindrical bundles of vessels, supposed to have been
roots which proceeded from the stem near its base; and an inner part
or axis. In the outer portion, the fossil _air-roots_ have a vascular
tissue, but there is often a delicate cellular tissue interposed. In
the axis the vessels form zigzag or wavy bands, resembling those of
ferns.[90] These flexuous and vermiform bands are entirely composed
of barred or scalariform vessels, similar to those of ferns and
club-mosses. The Psarolites are therefore considered by M. Ad.
Brongniart to be the bases of the trunks of lycopodiaceous trees, while
M. Cotta and other botanists regard them as true arborescent ferns.[91]
[90] Pict. Atlas, pl. viii.
[91] See M. Brongniart's "_Tableau des Genres de Végét. Foss._" p. 44.
Dr. Buckland has discovered in the New Bed sandstone formation at
Allesley, near Coventry, silicified trunks of coniferous trees, and it
is not improbable that further research in that locality may bring to
light fern-stems like those of Chemnitz.[92] Dr. Lloyd, of Warwick, has
recently obtained leaves of several coniferæ from the same locality.[93]
[92] Vide Geol. Proc. vol. ii. p. 438.
[93] Geol. Society, June 1852. Dr. Lloyd's specimens are probably
referable to the genus _Walchia_: see _Lign. 60._
[Sidenote: SIGILLARLÆ AND STIGMARIÆ.]
Sigillarlæ and Stigmariæ.
Among the most common and striking objects that arrest the attention
of a person who visits a coal-mine for the first time, and examines
the numerous vegetable relics that are profusely dispersed among the
heaps of slate, coal, and shale, are long flat slabs, from half an
inch to an inch thick, having both surfaces longitudinally fluted, and
uniformly pitted with deep symmetrical imprints; these are disposed
with such perfect regularity between the grooves, that the specimens
are often supposed, by persons not conversant with palæontology, to be
engraven stones, and not natural productions. These fossils are the
flattened trunks of gigantic trees covered by the bark in the state of
coal; the regular imprints on the surface, being the scars left by the
separation of the petioles or leaf-stalks, as in the arborescent ferns
previously examined. The name _Sigillaria_, commonly applied to these
fossils, is derived from _sigillum_, a seal, and alludes to the regular
and uniform pattern of the imprints on the surface. These stems are
from a few inches to several feet in diameter, and the largest attain
a height of sixty feet; they are generally found lying in a horizontal
position in the strata, and quite flat, from the pressure produced by
the superincumbent rocks; but when the trunks are in an erect position,
and at right angles to the plane of the beds, the cylindrical form of
the original is preserved.
A remarkable instance, in which five stems of Sigillaria were standing
upright, with their roots in the soil below, apparently in the position
in which they grew, was brought to light a few years since, in forming
the Bolton and Manchester railway.[94] They stand on the same plane,
and near to each other. Their roots are branched, and spread out in
the bed of impure coal in which they are implanted. The trunks are
surrounded by a soft blue shale. The largest tree is eleven feet high,
and seven and a half feet in circumference at the base; its trunk
is gnarled and knotted, and has many decorticated prominences, like
those in barked timber of our old dicotyledonous trees; the roots,
too, partake of the same character.[95] The others are respectively
from three to five feet in height. A sketch of one of the short stems
is subjoined. All the trees were broken off as if by violence, and no
traces of the upper part of the stems or branches were detected.
[94] These trees still remain _in situ_, and, thanks to the scientific
zeal of Mr. Hawkshaw, have been carefully preserved. They are situated
at Dixon Fold, Clifton, near Manchester. Instructive models of these
highly interesting relics of the carboniferous forests may be obtained.
An excellent Memoir on this discovery, with illustrations, by Mr.
Hawkshaw, is given in Geol. Trans, vol. vi. pl. xvii. See Pict. Atlas,
p. 198; and Petrifactions, p. 36.
[95] See Mr. Bowman's Memoir, Geol. Proc. vol. iii. p. 270.
[Illustration: Lign. 32. Base of a Trunk of a Sigillaria. with roots,
_standing erect with five other stems, in Carboniferous strata_.
(_The original is four feet high._)]
In the stratum through which the roots extend, a considerable quantity
of the fossil cones, called _Lepidostrobi_, hereafter described, were
imbedded (see _Lign. 40_). A thin layer of coal which invested the
stems, was evidently the carbonized bark. All the stems were filled
with blue clay, or shale, a proof that they were hollow when submerged
in the mud, which is now consolidated into the shale in which they are
imbedded. But it is not probable that they were originally tubular,
like a reed: on the contrary, there is evidence to show that they
were highly organized. Their internal structure may have decayed, or
been destroyed by insects or other depredators; as is often the case
in tropical climates, where the trunks of timber trees are speedily
excavated after their fall, and afford shelter to innumerable insects
and reptiles, as the weary traveller often finds to his surprise and
annoyance.[96] The late Mr. Bowman affirmed[97] that these trees were
dicotyledonous, and stated that medullary rays and coniferous structure
could be detected; an opinion, which the researches of M. Brongniart on
the Sigillariæ have fully corroborated.
[96] Mr. Hawkshaw, Geol. Proc. p. 269.
[97] Geol. Proc. vol. iii. p. 270.
* * * * *
[Sidenote: ERECT STIGMARIÆ.]
Many other instances have been noticed of Sigillariæ standing more or
less erect in the strata. In forming the railway tunnel at Claycross,
five miles south of Chesterfield, through the middle portion of the
Derbyshire coal-measures, in 1838, a group of nearly forty trees
(_Sigillariæ_) was discovered, standing not more than three or four
feet apart, at right angles to the plane of the strata.[98] On the
coast of Northumberland, within the length of half a mile, twenty trees
were observed by Mr. Trevelyan, in 1816 (_Bd._ p. 470). The coal-pit at
St. Etienne, in France, described by M. Alex. Brongniart, is celebrated
for affording an example of this phenomenon (_Wond._ p. 673); but the
positions of many of those stems are inclined at various angles, and
their roots implanted in different beds, so that the perpendicularity
of the erect trees is probably accidental (_Bd._ p. 471).
[98] Ibid. p. 272.
The most remarkable instance hitherto observed, is on the southern
shore of the Bay of Fundy, in Nova Scotia, where the cliffs, which are
about two hundred feet high, are composed of carboniferous strata,
consisting of coal, clay, grit, and shale, in which numerous erect
trees, probably Sigillariæ, are seen on the face of the cliff; there
are ten rows one above another, indicating, in the opinion of Sir C.
Lyell, repeated subsidences of the land, so as to allow of the growth
often successive forests![99] (_Wond._ p. 674).
[99] "On the Coal Strata of Nova Scotia." Amer. Journ. Oct. 1841 and
Travels in America, vol. ii. p. 180.
[Illustration: Lign. 33. Sigillariæ; _in Coal-shale_.
Fig. 1.--A specimen deprived of its carbonaceous bark, except in the
interstices of the channels, and showing pits left by the
external scars.
2.--The markings of S. Defrancii. (_Vég. Foss. Br._)
]
[Sidenote: SIGILLARLÆ.]
The stems of Sigillariæ vary in size from a few inches to five feet in
diameter; and in length from five to sixty feet; they gradually taper
from the base to the summit. A specimen measured by M. Brongniart was
forty feet long, one foot in diameter at the base, and but six inches
at the top, where it divided into two equal branches. These stems may
be readily distinguished from those of other trees with which they are
associated, by the fluted surface produced by the deep longitudinal
grooves, and the regularly disposed imprints between the channels.[100]
The carbonized bark, in large specimens, is often an inch thick, but
in small examples is a mere pellicle, and being extremely brittle,
flakes off with the slightest touch, leaving the inner surface exposed,
with the coal remaining in the deep furrows and pits, as in _Lign.
33, fig. 1_. No traces of leaves, or fruit, in connexion with the
stems, have been observed. The subjoined sketches (_Lign._ 33, and 34,)
illustrate the usual aspect of these fossils. The difference between
the imprints on the outside of the bark, and those on the exposed
surface of the stem, from the removal of the cortical covering, is well
marked in _Lign. 34_.
[100] The stems of some recent dicotyledonous trees from New Zealand, in
the possession of Dr. Robert Brown, possess similar longitudinal ribs
and furrows, both on the bark and alburnum, or naked wood.
[Illustration: Lign. 34. Sigillaria Saullii.
_Carb. Manchester._
_a._ The imprints of the petioles on the external surface of the
carbonized cortical investment.
_b._ The inner surface, exposed by the removal of the crust or bark.
]
Internal Structure of Sigillariæ.--Our knowledge of the structure of
this numerous tribe of plants, has received an important accession by
the discovery of the silicified fragment of a stem, which, fortunately
for the advancement of science, was placed at the disposal of M.
Adolphe Brongniart. It has been described and illustrated by that
eminent botanist, in a memoir which is one of the most valuable
contributions to fossil botany that has hitherto appeared.[101]
[101] The reader intending to make fossil botany his particular study,
should refer to the original memoir, and become familiar with the
facts and inferences so admirably enunciated by the author; not only
for the illustration of the structure of the tribe of plants under
consideration, but as a valuable exemplification of the manner in
which all such inquiries should be conducted. See _Archives du Muséum
d'Histoire Naturelle_, tom. i. Paris, 1839.
[Illustration: Lign. 35. Silicified Stem of Sigillaria elegans.
_Autun. France._ (_M. Adolphe Brongniart._)
Fig. 1.--A transverse section of the silicified stem, from Autun; _nat._
_a._ Situation of the medullary tissue, occupied by coloured
silex.
_b._ Zone composed of bundles of vessels, forming the woody
tissue.
_c._ Band of cellular tissue
_d._ Space between the ligneous cylinder and the bark, with no
evident structure, but originally occupied by the
external cellular tissue.
_e._ Zone of indistinct cellular substance.
_f._ External cortical envelopment, or bark.
2.--Portion of one of the vessels of the medullary tissue, as seen
in a longitudinal section, (× ×.)
3.--Portion of a spiral vessel of the same tissue. (× ×.)
]
The annexed figure (_Lign. 35_) is an outline of the specimen, of the
natural size; but this sketch is a mere plan or diagram, for it is
impossible without the aid of colour to convey a faithful idea of the
original. The student should observe, that when mineral matter has
permeated the stems of plants, the vascular tissue is often so well
preserved, that one such specimen affords more important information,
than hundreds of examples in which the form alone remains.
[Sidenote: SIGILLARLA ELEGANS.]
The external surface of this specimen possesses the characteristic
markings of the insertion of the leaf-stalks of _Sigillaria elegans_.
The internal organization, as seen in the transverse section, is as
follows:--
_a._ The centre, filled with silex; it exhibits no traces of structure.
_b._ The zone which surrounds the interspace on which this letter is
placed, is composed of bundles of vascular tissue. A portion of one of
these bundles, highly magnified, is represented in _Plate V. fig. 7_.
The _inner_ circle of this zone, indicated by the _convex undulating
line_, is made up of medullary vascular tissue; the external circle
is divided by rays, and is composed of woody fibre, constituting a
ligneous cylinder. One of the spiral vessels (_fig. 3_), and another
showing a remarkable difference of structure in a short space (_fig._
2), as seen in a longitudinal section of the medullary tissue, are
figured in _Lign. 35_.
The ligneous cylinder is surrounded by a band of cellular tissue, and
the space between this and the cortical integument is occupied by
silex, in which there are but obscure traces of structure.
The inner layer of bark, _f_, is composed of elongated cells, disposed
in a radiating manner, and traversed by fibro-vascular bundles, which
pass towards the leaves.
Upon instituting a comparison between the fossil and the stems of those
recent plants which present the closest analogy to it, M. Brongniart
was led to conclude that the Sigillariæ constituted a peculiar extinct
family, belonging to the great division of gymnospermous dicotyledons.
The Sigillariæ were tall erect trees, with a regular and cylindrical
stem, without side branches, but dichotomous towards the summit. Their
superficial bark was hard and durable, channelled longitudinally,
bearing leaf-scars that are of a rounded form above and below, and
angular at the sides, often oblong in relation to the stem, and having
three vascular pits, one central and small, and two lateral of a
larger size. The internal structure bears most analogy to that of the
Cycadeæ, and the foliage consisted of long linear carinated leaves.
The Sigillariæ, therefore, differ essentially from the arborescent
cryptogamia, which they somewhat approach in having scalariform
vascular tissue, symmetrical and regular leaf-scars, and branchless
trunks. More than fifty species have been determined.[102]
[102] For figures of Sigillariæ, see Pictorial Atlas, pl. xix. xx, xxiv.
[Sidenote: STIGMARIA.]
Stigmaria. _Lign. 36._--This extended notice of the structure of the
Sigillariæ,.will enable us to understand the nature of the fossil
vegetables termed Stigmariæ, or spotted-stems, which abound in the
beds of under-clay of most coal-fields, as stated in a former part
of this work (_ante_, p. 81). These bodies when uncompressed are of
a cylindrical form, from one to six or seven inches in diameter,
and of considerable length--sometimes upwards of twenty feet--and
gradually diminish in size towards their termination. The surface is
marked with distinct pits or areolæ, of a circular or oval form, with
a small tubercle in the centre of each, disposed around the stem in
a quincunx and somewhat regular order. When broken transversely, a
small cylindrical axis is seen to extend in a longitudinal direction
through the stem, like a medullary column; it seldom occupies the
centre, but lies near to one side, and parallel with a depression on
the outer surface of the fossil. This internal body is often loose,
and removable; its surface is covered with interrupted, irregular,
longitudinal, ridges, which leave corresponding depressions on the
walls of the cavity in which it was inclosed. _Lign. 36_, represents a
fragment exhibiting the characters above described.
[Illustration: Lign. 36. Stigmaria ficoides.
_Carboniferous. Derbyshire._--1/4 _nat._
Fig. 1.--Portion of a stem, with some of the rootlets (formerly
considered as leaves) extending into the surrounding
clay. The internal axis is seen at _a_; and the
corresponding groove on the portion of external surface
that remains.
2.--An outline of one of the rootlets, with a tubercle to show the
mode of its attachment by a ball and socket joint to the root.
]
When Stigmariæ are observed in the under-clay, to which stratum they
are principally confined, long, tapering, subcylindrical fibres, often
several feet in length, are seen affixed to the tubercles with which
the surface is covered; their form and mode of attachment are shown
in _Lign. 36_. Instances occur in which several Stigmariæ spring from
a common centre, of a dome-like form, whence they radiate in every
direction (_Bd._ pl. lvi. _fig._ 8), and the main branches divide and
subdivide till they are lost in the surrounding rock.
The nature of these fossil vegetables was long a perplexing question,
for no specimens had been found in connexion with any of the stems,
branches, or foliage, that abound in the coal deposits. At length,
the discovery of a dome-shaped mass, to which were attached numerous
Stigmariæ, seemed to afford a clue to the solution of this botanical
problem; and it was concluded by the eminent authors of the "Fossil
Flora of Great Britain," that the original belonged to a tribe of
plants which inhabited swamps, or still and shallow lakes, and were
characterized by a low truncated stem, having long horizontal branches
beset with cylindrical, and, probably, succulent leaves, that either
trailed on the surface of the swamp, or floated in the water.
But within the last few years, the occurrence in various carboniferous
deposits of erect stems of Sigillariæ, has shown that the Stigmariæ
are nothing more than the roots of these and other congenerous trees;
an opinion maintained by the Rev. H. Steinhaur more than thirty years
ago, and subsequently affirmed by M. Adolphe Brongniart, who found,
on examining microscopically the internal structure of a silicified
specimen in which the vascular tissue was preserved, that it bore as
close an analogy to that of the Sigillariæ, as exists between the roots
and trunks of certain dicotyledonous trees.
The annexed figure, _Lign. 37_, represents the transverse section of a
small Stigmaria, with the axis displaced from its natural situation;
this circumstance, as well as the corresponding external groove, has
arisen from compression, by which the tough cylinder has been forced
from its original position in the middle of the soft cellular tissue,
to one side.
[Illustration: Lign. 37. Transverse Section of Stigmaria ficoides;
_nat._
(_M. Adolphe Brongniart._)
This specimen shows that the cylinder (_a_ in _Lign. 36_) is formed of
bundles of vascular tissue, disposed in rays.]
The central axis is thus shown to be a cylinder composed of bundles of
vessels, disposed in a radiating manner, and separated from each other
by medullary rays; the whole constituting a ligneous zone resembling
that of Sigillaria (see _Lign. 35_); but the inner circle of medullary
tissue seen in the latter is altogether wanting. This difference is
similar to that observable in the stems or branches of a dicotyledonous
tree, in which the woody cylinder is associated internally with
bundles of medullary tissue, and the roots of the same tree that are
destitute of them. Part of a vascular bundle from the woody tissue of a
Stigmaria, seen by a high power and transmitted light, is figured _Pl.
V. fig. 6_; the smooth interspaces are composed of cellular tissue.
[Illustration: Lign. 38. Erect Stem of a Sigillaria, with roots.
_Coal Mine, near Liverpool._
_a._ The trunk of the tree, traversing a bed of Coal.
_b._ The roots (_Stigmariæ_) spreading out in the Under-clay.
]
[Sidenote: ERECT SIGILLARLA WITH ROOTS.]
This opinion of M. Brongniart was confirmed by the discovery, in 1843,
at St. Helen's, near Liverpool, of an upright trunk of a Sigillaria,
nine feet high, with ten roots eight or nine feet in length, still
attached, and extending in their natural position. _These roots
are undoubted Stigmariæ of the usual species, S. ficoides; and the
radicles, formerly considered leaves, are spread out in all directions,
to the extent of several feet._[103] To the sagacity and perseverance
of Mr. Binney, of Manchester, science is indebted for this important
discovery; the same gentleman laid bare, on the floor of the mine at
Dunkinfold, near Manchester, a large erect trunk of a Sigillaria, with
numerous Stigmariæ roots.
[103] From a communication to the British Association at Cork, 1843.
In the Pictou coal-field of Cape Breton, in Nova Scotia, similar facts
have been brought to light; the remarkable phenomena existing in that
locality, of successive carboniferous deposits containing scores of
erect trees with roots spreading into their native soil, presenting
peculiar facilities for verifying the observations made in England. In
an interesting memoir on the coal-fields of Nova Scotia, Mr. Richard
Brown has given a detailed account of numerous examples of stems of
Sigillariæ, and of Lepidodendra, (a tribe of gigantic club-mosses of
which we shall presently treat,) with the roots attached; these roots,
in every instance, had the characters and structure of Stigmariæ. In
one instance, the stem of the tree was broken off close to the roots,
and the hollow cylinder of bark was bent down and doubled over by the
pressure of the surrounding mud, so as effectually to close up the
aperture, and leave only a few irregular cicatrices converging near the
apex; this fossil explains the true nature of the "dome-shaped" plant
figured in the Fossil Flora, and in Dr. Buckland's Essay.[CZ]
[104] See Pictorial Atlas, p. 200: and Petrifactions, pp. 37, 38.
[Sidenote: LEPIDODENDRON.]
Lepidodendron (_scaly-tree_). _Lign. 39._--Stems cylindrical, covered
towards their extremities with simple, linear, or lanceolate leaves,
which are attached to elevated rhomboidal spaces, or papillæ; papillæ
marked in the upper part with a large transverse triangular scar; lower
part of the stem destitute of leaves.
[Illustration: Lign. 39.
Fig. 1.--A terminal Branch of a Lepidodendron; _nat._
2.--Leaf-scars on the stem of a Lepidodendron; _nat._
_In Coal-shale, Newcastle._]
The remains of this tribe of plants abound in the coal formation, and
rival in number and magnitude the Calamites and Sigillariæ previously
described. These trees have received the name of _Lepidodendra_, from
the scaly character of their stems, occasioned by the angular scars
left by the separation of the foliage, as is the case in arborescent
ferns: the term, however, simply indicates the appearance, for the
surface is not imbricated. Some of these trees have been found almost
entire, from the roots to their topmost branches. One specimen, forty
feet high, and thirteen feet in diameter at the base, divided towards
the summit into fifteen or twenty branches, was discovered in the
Jarrow coal-mine.[105] The foliage consists of simple, linear leaves,
spirally arranged around the stem, and appears to have been shed from
the base of the tree with age. The scars produced by the attachment of
the petioles were persistent; and the twigs and branches are generally
found covered with foliage, as in _Lign. 39_. The roots are Stigmariæ,
like those of the Sigillariæ, as proved by specimens in the Pictou
coal-field, discovered by Mr. Brown.[106]
[105] Wond, p. 722. This specimen is figured and described in Foss. Flor.
[106] Petrifactions, p. 39.
The internal organization of the stem of Lepidodendron differs from
that of Sigillaria, in the absence of the woody cylinder and medullary
rays which constitute so peculiar and important a character in the
latter. The Lepidodendra have only an eccentric, vascular, medullary
zone, the interval between which and the bark is filled up by cellular
tissue.[107] In their structure, external configuration, mode of
ramification, and disposition of the leaves, they accord so closely
with the _Lycopodiaceæ_, that, notwithstanding the disparity in
size, M. Brongniart, Dr. Joseph Hooker, and other eminent botanists,
concur in regarding them as gigantic arborescent club-mosses[108] The
living species of Lycopodiaceæ amount to nearly two hundred, the
greater number of which, like the arborescent ferns, inhabit the
islands of intertropical regions. They are diminutive plants, with
delicate foliage, none exceeding three feet in height; most of them
trail on the ground, but there are a few erect species, one of which
(_Lycopodium densum_) is abundant in New Zealand.
[107] See M. Ad. Brongniart, Archives du Museum d'Hist. Nat. torn. i.
(for 1839), pl. XXX.
[108] Figures of Lepidodendra in _Wond._ p. 718. Pict. Atlas, pl. i.
iii. ix. xxvi. xxvii. xxxiii.
The fruit of the Club-mosses is an oval or cylindrical cone, which
in some species is situated at the extremity of the branches, and
constitutes an imbricated spike. Now associated with the stems of the
Lepidodendra, and very often in masses of their foliage, and in some
instances attached to the extremities of the branches, are numerous
oblong, or sub-cylindrical, scaly cones, garnished with leaves. These
have received the names of _Lepidostrobi_ (scaly-cones), and are
unquestionably the fruit of the trees with which they are imbedded.
[Sidenote: LEPIDOSTROBUS.]
Lepidostrobus. _Lign. 40._--A cylindrical strobilus or cone, imbricated
from above downwards, composed of winged scales, terminating in
rhomboidal discs: the axis traversed by a longitudinal cavity or
receptacle.
These fossils have long been known to collectors, and are figured by
Martin (_Petrif._ _Derbiensia_), Parkinson (_Org. Rem._ vol. i. pl.
ix.), and others. They are cylindrical imbricated bodies, rounded at
both extremities, from two to six or seven inches in length, and one
or two inches in circumference. When broken asunder, a cylindrical
cavity is exposed, which is sometimes hollow, but commonly filled
with mineral matter; and when specimens are found imbedded in shale,
the cone is fringed with linear-lanceolate bracteæ, as in _Lign. 40,
fig. 3_. These fruits, like the fronds of ferns, often form the nuclei
of ironstone nodules, and the leaves are frequently replaced either
by a white hydrate of alumine, or by the mineral called galena, or
sulphuret of lead, and the receptacles filled with the same substances.
The specimens from Coalbrook Dale are generally in this state of
mineralization, and possess great brilliancy; they are interesting
examples of the electro-chemical changes which these fruits of the
carboniferous forests have undergone.[109]
[109] These fossil cones are not liable to decompose, like the pyritous
fruits from the Isle of Sheppey; they require no preparation for the
cabinet; washing injures their lustre; a soft brush will safely remove
any extraneous matter. There is a fine collection of Lepidostrobi in
the British Museum; see Petrifactions, p. 42.
[Illustration: Lign. 40. Lepidostrobi, the fruit of Lepidodendra; _nat._
_Coalbrook Dale._
Fig. 1.--A portion of a cone, showing the imbricated structure and
internal cavity.
2.--The upper part of a cone, displaying the imbricated surface.
3.--A young specimen attached to the extremity of a branch.
]
The figures in _Lign. 40_, represent the usual characters of these
fruits. Of the young specimen, (_fig. 3_,) situated at the termination
of a branch, M. Brongniart observes, "qu'il est impossible de ne pas
reconnaître pour un Lepidostrobus jeune, fixé à l'extrémité d'un
rameau."[110] As it is only in their young state that the spikes are
found attached to the branches, it is probable they were shed as soon
as they arrived at maturity.
[110] Hist. Vég. Foss. tom. ii. p. 47.
_Triplosporite._--Additional light has recently been thrown on the
structure of the Lepidostrobi, by Dr. Robert Brown's examination of
a silicified specimen of the upper part of a strobilus, in which the
internal organization is beautifully displayed. The reader specially
interested in this department of fossil botany should refer to the
original memoir by the illustrious President of the Linnæan Society,
with the accompanying plates that admirably exhibit the microscopic
analysis of the structure of this remarkable fossil; a slice of which
was shown me some years since by the late Marquis of Northampton.[111]
The external surface of the specimen is covered with hexagonal areolæ;
the transverse sections exhibit the appearance of the bracteæ and
sporangia. The strobilus is formed of a central axis of relatively
small diameter, from which proceed bracteæ, about thirteen in number,
that are densely approximated, and much imbricated; and of an equal
number of sporangia, filled with innumerable microscopic sporules,
originally connected in threes. This triple composition of sporules
(which differs from the constant quadruple union in the tribes of
existing plants presumed to be most nearly allied to the fossil,
namely the _Ophioglosseæ_ and _Lycopodiaceæ_) is expressed by the name
_Triplosporite_, adopted by Dr. Brown to indicate this peculiarity of
structure, and the class or primary division to which the original
plant is supposed to belong.[112]
[111] The specimen brought to England was but two inches of the upper
end of the cone; it was purchased conjointly by Lord Northampton, Dr.
Brown, and the British Museum, for 30_l._!
[112] See Trans. Linnæan Society of London, vol. xx. p. 469.
Lycopodites.--Species of true Lycopodiaceæ occur in tertiary marls; a
beautiful specimen, from Germany, _Lycopodites_ _Benettiæ_, is figured
_Wond._ p. 723.
[Sidenote: HALONIA. KNORRIA.]
Halonia; Knorria. _Lign. 41._--Associated with the plants already
described from the coal-measures, there are trunks and branches of
other trees, presenting peculiar and but imperfectly known characters,
which it will be convenient to notice in this place. Fragments of these
stems are to be seen in most public collections of the carboniferous
flora, and should be examined by the student, for figures and
descriptions can convey but an imperfect idea of their nature.
* * * * *
Mr. Denny, the intelligent and indefatigable Curator of the Leeds
Philosophical Society, has given the following admirable summary of the
distinctive characters of the stems of most frequent occurrence in the
Coal,[113] which will be found a useful guide to the collector.
[113] On the Fossil Flora of the Carboniferous Epoch, with especial
reference to the Yorkshire Coal-field. By Mr. Henry Denny, A.L.S.
Proceedings of the Polytechnic Society of Yorkshire; for 1850.
1. _Sigillaria._--Stem furrowed, not branched, leaf-scars small, round,
much narrower than the ridges of the stem.
2. _Favularia._--Stem furrowed, not branched, leaf-scars small, square,
and as broad as the ridges of the stem.
3. _Lepidodendron._--Stem not furrowed, branched, covered with
lozenge-shaped scars in quincuncial order, each having a papilla in
the upper part; the upper portion of the stem and branches with simple
linear leaves; the lower portion destitute of leaves.
4. _Halonia._--Stem not furrowed, branched, covered with indistinct
rhomboidal marks, and tubercular projections disposed in quincunx.
5. _Knorria._--Stem not furrowed, branched, marked with projecting
scars of petioles disposed spirally.
6. _Megaphyton._--Stem dotted, neither furrowed nor branched,
leaf-scars very large, of a horse-shoe figure.[114]
[114] Pictorial Atlas, pl. xxv.
7. _Bothrodendron._--Stem pitted, neither furrowed nor branched, scars
of cones (?) obliquely oval.
8. _Ulodendron._--Stem neither furrowed nor branched, covered with
rhomboidal marks; scars of cones (?) circular.
The characters of the roots called Stigmariæ (_ante_, p. 134), and
of the stems named _Calamities_ (ante, p. 107), and _Equisetites_
(_ante_, p. 106), are sufficiently distinct from the above to be easily
recognized, I will briefly notice those not previously described.
[Illustration: Lign. 41. Stems from the Coal Formation.
Fig. 1.--Halonia regularis. _Coalbrook Dale._
2.--Knorria Taxina. _Roof of the High-main Coal seam, Jarrow
Colliery._ (_Brit. Foss. Flor._)
]
_Halonia._--The specimens usually seen are mere sandstone casts
having a thin carbonaceous crust; the stem is branched and beset
with large elevated knobs, or subcortical protuberances, as shown in
_fig. 1, Lign. 41_. These plants appear to be closely related to the
Lepidodendra; their mode of branching is shown in a beautiful specimen
(in the museum of the Leeds Philos. Soc.) figured and described by Mr.
Denny, which is also remarkable because it indicates the probability
that the Haloniæ, and the fossil stems, termed Knorriæ, are identical;
for the specimen in question, which in its branches is unquestionably
of the former type, has the base of the stem impressed with the
leaf-scars of the latter.
_Knorria._--To this genus the authors of the Fossil Flora of Great
Britain referred those stems which have projecting leaf-scars, arranged
spirally. The beautiful specimen figured as _Knorria taxina_, _Lign.
41, fig. 2_, closely resembles a young branch of Yew (_Taxus_), and
perhaps might be more correctly named _Taxites_.
_Bothrodendron and Ulodendron._--These genera, together with
_Megaphyton_, are stems of a very remarkable character, and are easily
distinguished by the vertical rows of large and distant scars. The two
first have two series of very deep oval depressions on opposite sides
of the stems, arranged alternately in the specimens I have examined:
from the size and form of these obliquely-oval cavities, it is supposed
that they were formed by the attachment of cones, and not by petioles;
but their real nature is involved in obscurity.[115]
[115] Figured in Bd. pl. lvi.
In _Megaphyton_, the large ovate scars indicate the attachment of
deciduous branches or gigantic leaves, which did not grow all round the
stem, but in a regular order of superposition on each side.[116]
[116] Figured in Pict. Atlas, pl. xxv.
[Sidenote: ASTEROPHYLLITES.]
Asterophyllites.--I shall conclude this notice of some of the most
characteristic trees of the Carboniferous Flora, with an account of a
tribe of plants whose remains are so common in the coal-shales and
grits, that there are but few large slabs with vegetable remains that
do not exhibit examples of the elegant verticillate foliage of one or
more species. The term _Asterophyllites_, (expressive of the star-like
form of the leaves,) applied to this family by M. Ad. Brongniart,
includes several fossil plants which are known to geologists under
different generic names; the following concise account may be useful to
the student.[117]
[117] Consult _Tableau des Genres de Végétaux Fossiles_, par M. Ad.
Brongniart. Diet. d'Hist. Nat. Paris, 1849.
1. _Calamodendron._--These are arborescent stems, ligneous internally,
and covered with a smooth carbonaceous crust, without regular
longitudinal striæ, and not articulated; but the woody axis covered
by this bark is deeply striated and articulated, resembling in this
respect the true Calamites. These stems have a large central pith,
or medullary column, surrounded by a ligneous zone, which is formed
of radiated bands, without circles of growth: the structure of the
carbonized bark is unknown.
2. _Asterophyllites._--These are supposed to be the branches and
foliage of the stems above described.
3. _Sphenophyllum._--Plants, differing in the form of the leaves,
but analogous in structure and mode of fructification to the
Asterophyllites.
4. _Annularia._--Herbaceous aquatic plants, distinct from the preceding.
5. _Volkmannia._--These fossil plants are Asterophyllites in
fructification.
The _Asterophyllites_ (_Lign. 42_) had branched articulated stems,
with verticillate leaves, arranged perpendicularly to the branches
which supported them: but as the foliage is in most instances partially
concealed, the natural form is but seldom observable.
The original plants are supposed to have been a tribe of flowering
dicotyledons, for small seed-vessels resembling those of the Cypress
are often found with the foliage.
[Illustration: Lign. 42.
Asterophyllites equisetiformis; _nat._
_Coal-shale._ (_Foss. Flor._)]
[Sidenote: ANNULARIA CARDIOCARPON.]
The _Annulariæ_ were herbaceous plants with verticillate foliage
like the former, but the whorls were arranged on the same plane with
the stems on which they grew, and their remains have a very elegant
appearance when expanded in the coal schists. It is supposed that they
were aquatic plants, and that the stems and leaves floated on the
surface of the water.[118]
[118] _Wond._ p. 717. Petrifactions, pp. 27, 43, &c. For coloured
figures see Pictorial Atlas, pl. v.
Sphenophyllum (_wedge-shaped leaf_). _Lign. 43._--The fossil vegetables
thus named, though somewhat resembling in their elegant verticillate
foliage the Asterophyllites, differ essentially, and are regarded by
M. Brongniart as herbaceous plants related to the _Marsiliaceæ_, or
Pepper-worts. The leaves are triangular, truncated at the summit, and
very deeply lobed and dentated. The fructification consists of sessile
axillary or terminal spikes, composed of verticillate bracteæ, covering
the receptacles. This mode of fructification resembles that of the
Asterophyllites.[119]
[119] For details consult _Tab. des Genres de Vég. Foss._ p. 52.
Cardiocarpon.--_Lign. 44. fig. 1._--These are small fossil fruits or
seed-vessels, which much resemble those of the Thuja or _Arbor-vitæ_,
and are so often found imbedded with masses of the foliage of
Asterophyllites, that it is conjectured they belong to those plants.
They occur in groups of from five to twenty, and evidently were
_didymous_, _i.e._ grew in pairs. _Fig. 1a_. is an enlarged view, to
show the surface left by the attachment of the twin-seed.
[Illustration: Lign. 43.
Fig. 1.--Sphenophyllum Schlotheimii; _nat._
2.--Sphenophyllum erosum.
_Coal-Shale._]
Trigonocarpum. _Lign. 44. figs. 3. 4._--These fruits, which resemble
those of certain Palms, are often met with in the coal-mines of
Leicestershire and Yorkshire; frequently occurring in groups of thirty
or forty, as if they were the scattered seeds of a raceme of a Palm:
they are referred to the genus Nœggerathia, a tree of the carboniferous
formation allied to the Palms.
[Sidenote: FOSSIL FRUITS.]
A figure of a fossil fruit from the Oolite--Carpolithes Bucklandi, is
introduced in _Lign. 44, fig. 2_, and will be described hereafter.
[Illustration: Lign. 44. Fossil Fruits, or Seed-vessels; _nat._
Fig. 1.--Cardiocarpon acutum. _Snibstone Coal-mine, Leicestershire._
1_a_.--One of the above magnified.
2.--Carpolithes Bucklandii. _Coralline Oolite, Malton._
3.--Trigonocarpum olivæforme. _Snibstone Colliery._
4.--Trigonocarpum Nöggerathi.
]
The reader will observe that the fossil vegetables hitherto described
belong, with but few exceptions, to the Carboniferous flora; and that
the remains of Ferns, Calamites, Sigillariæ, and Lepidodendra, compose
in a great measure those prodigious accumulations of mineral fuel, or
coal, which supply the luxuries and necessities created by civilization.
Our review of fossil plants will now assume somewhat of a botanical
arrangement, and we proceed to notice some of the most characteristic
vegetable forms of the secondary and tertiary formations. We commence
our examination with those remarkable tribes of gymnosperms, the
Cycadaceæ, which comprise the Zamiæ and Cycadeæ.
Fossil Cycadaceæ.
The plants of this subdivision of the vegetable kingdom, from their
singular structure and mode of growth, their simple cylindrical stems,
and coronets of pinnated foliage, resembling that of certain palms,
their usually gyrate vernation like that of the ferns, and their
anomalous inflorescence and fructification, are objects of great
interest to the scientific botanist; while the abundance of their
fossil remains in the secondary formations renders them of the highest
importance to the geologist.
[Illustration: Lign. 45.
Foliage and upper part of the Stem of Cycas revoluta 1/12 _nat._
_In Kew Conservatory._]
As many kinds of Zamia[120] and Cycas are cultivated in our hot-houses,
the general appearance of the plants of this order must be familiar to
the reader: the annexed figure of a beautiful living Cycas in the Royal
Gardens at Kew, will serve to illustrate the general aspect of these
exotics.
[120] The Linnæan genus Zamia is now separated into five or six genera,
as Encephalartos, Macrozamia, Dion, &c.
The Zamiæ are short plants, with stout cylindrical stems, beset
with thick scales, which are the bases of the petioles that have
been shed: towards the summit the stem is garnished with a crown of
elegant leaves; the fruit resembles the cones of pines. The leaves
are pinnated, and very tough; their venation is either parallel as
in endogens, or dichotomous as in ferns, but never reticulated as in
exogens: in a young state they are coiled up like a crosier, as in
ferns.
The Cycadeæ have the general aspect of the Zamiæ, but differ in their
fructification and other characters; and some species have the stem
bifurcated towards the top, and attain a height of upwards of twenty
feet; for example, _C. circinalis_.
The stem in its internal structure[121] bears a close analogy to that
of the Coniferæ; it has a central medullary column surrounded by a
ligneous cylinder, divided by cellular medullary rays, each composed
of bundles of vessels, and a thick cellular cortical investment or
false-bark,[122] composed of the persistent scales that formed the bases
of the petioles. (See _Pl. V. fig. 5._)
[121] See _Bd._ pl. lxii.
[122] See _Bd._ vol. i. pp. 494-498, for detailed description of
structure in recent and fossil Zamiæ and Cycadeæ.
The existing species of Cycadaceæ are exclusively natives of hot
regions, and chiefly inhabit the West Indies, South Africa, Equinoctial
America, Japan, New Holland, &c.; not one species is known in Europe: a
fact in striking contrast with the abundance of fossil plants of this
order, which occur throughout the secondary formations of England and
the continent.[123]
[123] The most interesting collection of living Cycadeæ and Zamiæ near
London, is that of James Yates, Esq., of Lauderdale House, Highgate; it
comprises choice examples of several of the sub-genera into which these
plants are now divided by botanists.
No true cycads have hitherto been discovered in the carboniferous
deposits; it is in the floras of the secondary epochs, from the new
Red to the Cretaceous inclusive, that this tribe of plants forms an
important feature. The foliage, stems, and fruits, occur in a fossil
state; and as these organs cannot be referred with certainty to their
respective plants, distinct genera are formed for their reception.
_Foliage._--From the tough and durable nature of the leaves, the
foliage of the Cycadeæ occurs in a fine state of preservation; and in
the fluvio-marine deposits of the Oolite of Yorkshire, many specimens
of great beauty have been collected. I know not another locality in
England so rich in fossils of this kind, as the cliffs along the coast
near Scarborough; Gristhorpe Bay is well known to collectors. Not only
the leaves, but also the fruits or cones occur, and of these, examples
are to be seen in most public museums.[124] The leaves are carbonized,
but the venation is well preserved.
[124] British Museum: see Petrifactions, p. 54, Room 1, Case F.
[Illustration: Lign. 46. Part of a leaf of Pterophyllum comptum; _nat._
_Oolite, Scarborough._]
The leaflet of the recent Cycas is distinguished by a strong nervure,
which runs along the middle; that of Zamia has no midrib, but fine
parallel veins that pass direct to the margin.
Pterophyllum comptum. _Lign. 46._--The general aspect of these
fossils is shown in this figure of a leaf, referred to the genus
_Pterophyllum_, which is characterized by leaflets, often slightly
united at their base, truncated at the summit, of a quadrangular or
oblong form, and having fine, straight, parallel veins. The leaves are
ten or twelve inches long, and have fine lanceolate leaflets; they are
abundant in the same beds, and are often associated with the cones or
fruit[125] figured in _Lign. 48_.
[125] Brit. Mus. Petrifactions, p. 55.
[Sidenote: ZAMITES PECTINATUS.]
Zamites pectinatus. _Lign. 47._--In the Stonesfield slate, collocated
with remains of reptiles, fishes, insects, and mollusks, leaves and
fruits of cycads are occasionally met with. A portion of a leaf nine
inches long is here figured. The Lias of Dorsetshire has yielded many
beautiful relics of this family[126]
[126] In the carboniferous strata of Eastern Virginia, United States,
which are referred by Professor Rogers to the Oolitic epoch, leaves of
Cycadeous plants are abundant. See Trans. American Geol p. 298.
[Illustration: Lign. 47. Part of a leaf of Zamites pectinatus; _nat._
_Oolite, Stonesfield._]
But few vestiges of the foliage of Cycads have been observed in
the Wealden formation of England; one elegant leaf, however, of an
undescribed species, was obtained some years since, from a sandstone
quarry in Surrey, and is figured in my Geology of the South-east of
England, p. 238; it is named in honour of my distinguished friend, M.
Ad. Brongniart, _Cycadites Brongniarti_. The Wealden of the north of
Germany is very rich in fossil Cycadeæ; my friend. Dr. Dunker, has
figured and described twelve species in his admirable work on the
organic remains of that formation.[127]
[127] Mon. Norddeutschen Weald, tab. i. to vii.
_Fruits._--The cones or fruits which occur with the foliage of Zamiæ
in the carbonaceous shales and marls of the Oolite of the Yorkshire
coast, are very fine, and have been described under the various names
of _Zamites Mantelli_, _Z. gigas_, and _Z. lanceolatus_.
An interesting memoir on the structure of these fossils, by James
Yates, Esq. (a gentleman distinguished for his knowledge of the
recent Cycadaceæ), is published in the Proceedings of the Yorkshire
Philosophical Society for 1849, p. 37; and another communication on
the same subject by my friend Professor Williamson, of Manchester, in
_York. Phil. Trans._ 1819, p. 45; to these papers I must refer for
a detailed account of all that is at present known respecting their
organization.
[Illustration: Lign. 48. Fruit of Zamites Mantelli, (_Brongniart_);
_nat._
_From near Scarborough._
The surface of the cone is concealed by the bracteæ.]
Zamites Mantelli.[128] _Lign. 48._--The leaves associated with the fruit
here figured, have lanceolate leaflets that insensibly contract at the
base, and are inserted obliquely into the rachis; thus resembling
the foliage of the recent _Encephalartos_. With these leaves, and the
ovate cones (_Lign. 48_), are occasionally found a circle of leaves
or elongated scales, locally termed "_collars_," which Professor
Williamson has shown to be a zone formed by a scaly bud in which the
germ of the plants was inclosed. In the progress of development, the
fruit burst through the upper part of the investing sheath, and, as it
grew to maturity, rose above the incurved elongated bracteæ, till the
latter formed a zone or "collar" around the pedicle of the cone.[129]
These fossils have been mistaken for flowers.[130]
[128] _Podozamites_ of Braun.
[129] Proc. Yorkshire Philos. Soc. 1849, p. 45.
[130] Bird's Yorkshire, tab. i. figs. 1 and 7.
It does not appear that the structure of the cone has been preserved
in any of the specimens, so as to demonstrate the characters of the
original; in all those I have examined, the surface of the fruit is
concealed by the elongated bracteæ, which are pressed flat, and adhere
so firmly to the inclosed body, as to render it impossible to ascertain
its nature.[131] Mr. Williamson is of opinion that the plant resembled
the recent _Cycas circinalis_, in its great height, and lax habits; and
states, that he had seen portions of leaves that were three feet in
length.
[131] Brit. Mus. Petrif. p. 55.
Zamites crassus. _Lign. 49, fig. 1._--In Sandown Bay, on the south
coast of the Isle of Wight, where the Wealden beds rise to the surface
from beneath the lowest strata of Greensand on the east and west,
several cones have been found, associated with other vegetable remains,
and bones of the Iguanodon, &c. A fossil cone from this locality is
here figured; it bears considerable resemblance to the fruit of the
recent _Encephalartos_.
[Sidenote: ZAMITES OVATUS.]
Zamites ovatus. _Lign. 49, fig. 2._--A few examples of cycadeous
fruits have been collected from the Greensand of Kent and Sussex. The
beautiful fossil represented, _Lign. 49, fig. 2_, from Foss. Flor.
is referred to the Zamiæ, by the eminent authors of that work; but it
presents in its imbricated character a greater analogy to a pine cone.
[Illustration: Lign. 49. Fossil Fruits of Cycadeous Plants; 1/2 _nat._
Fig. 1.--Zamites Crassus. _Wealden, Isle of Wight._
2.--Zamites Ovatus. _Greensand, Kent._
]
Zamites Sussexiensis.--At Willingdon, near Eastbourn, in Sussex, a cone
nearly six inches long was discovered in a bed of Greensand, which
abounds in fossil coniferous wood: it is of an elongated cylindrical
form, and covered with hexagonal scales. I have provisionally named
it _Zamites Sussexiensis_ (Geol. Proc. 1843), as it presents a nearer
resemblance to the fruit of Zamiæ than to that of Conifers.
Trunks and Stems of Cycadaceæ.--In this section I shall notice the
fossil plants which occur so abundantly in the fresh-water deposits
that overlie the marine oolitic limestone of the Isle of Portland, and
which must be familiar to my readers, from the graphic account of the
circumstances under which they occur, by Mr. Webster, and subsequently
by Dr. Buckland, and Sir H. De la Beche. In my Wonders of Geology,
p. 387, and Geol. Isle of Wight, p. 395, the geological phenomena of
that most interesting locality, the Isle of Portland, are so fully
described, that it will not be necessary to dwell upon them; the
structure and affinities of the fossil vegetables are the especial
objects of our present inquiry.
[Sidenote: MANTELLIA NIDIFORMIS.]
[Illustration: Lign. 50. Silicified Trunk of Mantellia nidiformis
(_Brongn._); 1/4 _nat._
(_Cycadites megalophyllus._ _Bd._)
_Wealden. Isle of Portland._
_a._ Central mass of cellular tissue, _b._ Circle of ligneous plates,
_c._ Zone of cellular tissue, _d._ False-bark.]
Mantellia. _Lign. 50, 51._--The fossil Cycadeæ of the Isle of Portland
were first described botanically by Dr. Buckland, (Geol. Trans, vol.
ii. 2d Series,) under the name of _Cycadeoidea_; of which Memoir the
account in _Bd._ p. 404, is an abstract. M. Ad. Brongniart, considering
these plants as a peculiar type, referred them to a new genus, which he
did me the honour to name _Mantellia_ (_Prod. Veg. Foss._). These stems
or trunks are from one to two feet in height; the circumference of the
largest not exceeding three feet. The stem is subcylindrical, and
the external surface covered with the rhomboidal scars formed by the
attachment of the leaf-stalks, and which are widest in their transverse
diameter.
There are two species, which are readily distinguished by the form of
the stems, and the difference in the size of the cicatrices left by the
petioles.
The most common kind is short, and spheroidal, and the leaf-scars are
relatively large; its shape has caused it to be named "_Crows' nest_,"
by the quarrymen, who believe these plants to be nests that were built
by crows in the trees of the petrified forest with which they are
imbedded. The specific name (_nidiformis_) adopted by M. Brongniart,
expresses this popular notion.
_Lign. 50._ represents a fine example from the Portland Dirt-bed, which
exhibits a structure altogether similar to that which characterizes
the stems of recent cycadeous plants; namely, (_a_) a central mass of
cellular tissue surrounded by circles of laminated ligneous rays or
plates (_b_); then a zone of cellular tissue (_c_), and an external
cylinder of false-bark (_d_). The mode of increase by buds, from
germs in the axillæ of the petioles, as in the living plants, is also
distinctly seen.
[Illustration: Lign. 51. Mantellia cylindrica.
(_Brongn._); 1/8 _nat._
(_Cycadites microphyllus. Bd._)
_Wealden. Petrified Forest of the Isle of Portland._]
The other species is subcylindrical, and the leaf-scars are much
smaller and more regular than in _M. nidiformis_, indicating a more
delicate foliage, as expressed by Buckland's specific name: that of M.
Brongniart refers to the cylindrical form of the stem. This plant was
higher and more slender than its associate. Numerous buds are seen in
the axillæ of the petioles in the specimen figured.
These fossils present, both externally and internally, a close relation
to the bulbiform stems of the recent Cycadeæ, named _Encephalartos_, of
South Africa.[132]
[132] The fossil Cycads of the Isle of Portland are admirably described
and illustrated in Dr. Buckland's Bridgewater Essay, (p. 497, and pl.
lx. lxi.), and their internal structure is fully explained.
Neither the leaves nor the fruit are known: a cone found in the
Dirt-bed of Portland, and attributed to these plants, appears to belong
to the coniferæ of the petrified forest. Examples of Mantelliæ have
been found in the quarry of Portland-stone at Swindon, Wilts.
[Sidenote: CLATHRARIA LYELLII.]
[Illustration: Lign. 52. Clathraria Lyellii.
_Wealden._
A branched example of the inner axis: the original 3-1/2 feet high.]
Clathraria[133] Lyellii. _Lign. 52-57._--The fossil plants to which I
would next direct attention were first discovered by me in the Wealden
strata of Sussex, in 1820, and were figured and described under the
name they still bear, in my Fossils of Tilgate Forest, in 1827. The
specimens figured in that work are the most illustrative hitherto
discovered, with but one exception.[134]
[133] EC C
lathraria, _i.e._ _lattice stem_, from the scars left by the
petioles.
[134] They are now in the British Museum; see Petrifactions, p. 45.
_Room_ I. _Case_ E.
From the imperfect state of the remains of these plants, the structure
and affinities of the originals were very ambiguous, and the fossils
have been placed by some eminent botanists with the Liliaceæ, and by
others with the Asphodeleæ; their true botanical position is doubtless
with the Cycadaceæ; for in some points they resemble the Zamiæ, in
others the Cycadeæ.
The stem of the Clathraria is composed of a solid internal axis, the
surface of which is covered with reticulated fibres; the large branched
specimen of this part, figured in _Lign. 52_, is the finest example
hitherto obtained: it was discovered, with bones of the Iguanodon,
in a quarry near Cuckfield, Sussex, in 1820. The axis is invested
with a very thick false-bark, formed of the consolidated bases of the
leaf-stalks, the insertions of which are rhomboidal and transverse.
The outer surface of the bark is consequently marked with elevated
lozenge-shaped cicatrices (_Lign. 53_), separated from each other by a
marginal furrow, which is surrounded by a parallel ridge or band of a
fibrous structure.
[Illustration: Lign. 53. Clathraria Lyellii.
1/4 _nat._
A stem, with rhomboidal transverse scars, left by the petioles; broken
transversely and separated, to show the internal axis at _a_, which,
if the pieces were united, would be received in the cavity below the
depression, or cicatrix, on the middle of the upper portion, _b_, was
probably the situation of a resinous secretion, like the dragon-blood
in the Dracæna.]
The cortical zone is generally converted into a cylinder of stone,
which in some examples separates from the axis. In a beautiful specimen
of this kind, _Lign. 54_, the axis projects and is surrounded by the
false-bark.
The axis is solid, and has its surface strongly marked with interrupted
ridges. This surface has generally patches of vascular tissue adhering
to it; and there are here and there deep pits, or lacunæ, which
probably contained a resinous secretion. Thin transverse sections
of the axis, prepared with Canada balsam, and examined under the
microscope, only give faint traces of cellular tissue.
[Illustration: Lign. 54.
Clathraria Lyellii; 1/4 _nat._
_Wealden Sandstone._
_Tilgate Forest._
Portion of a stem, scored by the cicatrices of the petioles; showing
the Axis _a_, surrounded by the cortical cylinder.]
I have spared neither trouble nor expense in endeavouring to detect
the organization of this plant; numerous sections of stems have been
cut, and examined microscopically, but very few exhibit any traces of
structure; and in those which retain some vestiges of organization,
the siliceous mass which permeates the vascular tissue, is not
sufficiently transparent to yield satisfactory results. It can only
be inferred that in their internal organization, as in their external
characters, the Clathrariæ were most nearly allied to the Cycadeæ or
Zamiæ. A remarkable specimen, (_Lign. 56_,) discovered in a stratum of
Chalk-marl, near Bonchurch, confirms this view, and throws much light
on the nature and relations of these vegetables.
[Illustration: Lign. 55.
Petiole of Clathraria Lyellii;
_a._ External aspect.
_b._ Inner surface.
_c._ Vascular pits left by the separation of the leaf.
]
This fossil is a portion of the summit of a stem garnished with
persistent petioles, or leaf-stalks; it is fifteen inches in length,
and nearly perfect at the top; and at the lower end, which has been
broken off transversely, the inner axis (_Lign. 56 a_.), surrounded
by the false-bark formed by the confluence and consolidation of the
bases of the petioles, is exposed. The stem has been stript of the
leaf-stalks at the lowermost part, and exhibits the characteristic
lattice-like scars. The petioles are for the most part entire; some of
them are abortive, and others, which have supported leaves, are marked
on the summits with vascular pits, indicating that the foliage was
shed naturally; as shown in _Lign. 55 a_. These petioles were probably
persistent for some years, as in the existing Cycads. The opposite side
of the stem to that represented is covered with elongated and flattened
petioles.
[Illustration: Lign. 56.
Clathraria Lyellii; 1/4 _nat._
_Chalk-marl. Bonchurch, Isle of Wight._
The summit of a stem garnished with petioles; the lower part shows
the cicatrices left by the removal of some of the petioles: _a_, the
internal axis.]
On the sea-shore bounded by cliffs of Wealden rocks, in the Isle of
Wight, water-worn portions of stems of Clathrariæ are occasionally met
with; and these are impressed with the lozenge-shaped areas left by the
petioles, as in the specimen, _Lign. 57_. Mr. Saxby, of Bonchurch, has
favoured me with the loan of a thin section of a stem of Clathraria in
which the bundles of vascular tissue in the petioles appear to be made
up of spiral vessels. From what has been advanced, it is obvious that
these remarkable plants of the Wealden flora were gymnosperms, closely
related to the Cycadeæ.
Vestiges of roots, seed-vessels, and panicles, have been found in the
Wealden, which may possibly belong to the Clathraria; but the evidence
as to their presumed relationship is at present too vague to require
further notice.
[Illustration: Lign. 57.
Clathraria Lyellii; 1/2 _nat._
Specimen, showing the water-worn external surface.]
[Sidenote: ENDOGENITES.]
Endogenites erosa.--(_Geol S. E._ pl. i.; Tilg. Foss. pl. iii.; and by
Dr. Fitton in _Geol. Trans._ vol. iv.)--The genus _Endogenites_ was
established by M. Ad. Brongniart for the reception of those fossil
stems and woods, whose internal structure is endogenous, but which are
too imperfect to be referred to any particular family. In this category
must be placed certain silicified stems having a carbonaceous cortical
investment, which I discovered in the strata of Tilgate Forest, in 1820.
These fossils often occur in the layers of lignite which traverse the
clay-beds in some parts of the Weald of Sussex. They are from one to
eight inches in diameter, and five or six feet in length, and of very
irregular shapes; I have not observed any indications of branches.
Some specimens are subcylindrical in the middle, and gradually taper
to a point at each end; others are of a depressed clavated form, like
some of the Cacteæ or Euphorbiaceæ. They are generally silicified,
and, when _in situ_, are invested with a friable carbonaceous crust,
of a glossy lustre, which soon falls to pieces on exposure to the
atmosphere, so that cabinet specimens seldom retain any vestiges of it.
When this coaly matter is removed, the surface of the silicified stem
is seen to be traversed by numerous fine meandering grooves, and deep,
tortuous channels, disposed in an irregular manner, in a longitudinal
direction. These channels or vessels, which are generally lined
with quartz crystals, give the surface that eroded appearance which
suggested the specific name, erosa; but this term is inapplicable,
for the perforations and sinuosities are not the effect of erosion,
but result from the structure of the original. Polished sections,
seen by transmitted light, are represented in Dr. Fitton's memoir
(_Geol. Trans._ vol. iv.); and I have had many slices ground as thin
as possible, in the hope of detecting the characters of the vascular
tissue. In one example there are indications of a cycadeous structure,
which favour the conclusion, that the originals belonged to an extinct
tribe of gymnosperms; but in other specimens, bundles of vascular
tissue, resembling those of palms, are apparent.
Large water-worn stems of _Endogenites_ are occasionally washed out of
the Wealden cliffs at Hastings, and in Sandown and Brook Bays, in the
Isle of Wight.
[Sidenote: FOSSIL CONIFERÆ.]
Fossil coniferæ.
The other great natural order of Gymnospermous phanerogamiæ,[135] the
_Coniferæ_, or cone-bearing--so named from the form of their fruit, of
which the fir-cones and larch-juli are familiar examples,--comprise the
extensive tribes of Firs and Pines, and the Cypresses, Yews, Junipers,
Cedars, &c., among which are the loftiest trees on the face of the
globe.
[135] Signifying, flowering plants with naked seeds.
The Conifers are all arborescent, having numerous branches, which are
in general disposed with much regularity. The leaves are commonly
acicular or needle-shaped, narrow, and linear: in two or three genera,
however, (_Dammara_, _Podocarpus_,) the foliage departs remarkably from
the ordinary type, the leaves being broad and flat. The structure of
the stem, though in its general characters essentially exogenous (see
_Plate IV. fig. 4_),--that is, having a central pith, medullary rays,
zones of vascular tissue, and concentric circles of growth,--differs
in the almost entire absence of spiral vessels, and in the peculiar
modification of the radiating bands of woody fibre, which are made up
of uniform longitudinal vessels, and run parallel with the medullary
rays. The lateral walls of these vessels have longitudinal rows of
areolæ, which are generally circular or elliptical, but when in contact
are angular and polygonal: each areola has a small pore or punctation
in the centre. These discs, glands, or ducts, as they are called, are
variously arranged in different genera; they are generally confined to
the contiguous and corresponding lateral surfaces of the fibres; and
occur rarely, if ever, on the inner and outer aspects of the vessels.
In the recent genus Pinus the rows of ducts are single in some species;
in others both single and double series occur, but never more than two,
and in the latter case the ducts are always parallel to each other (see
pl. v. 3_b_. _Wond._ pp. 696, 725). But in the _Araucariæ_, or Norfolk
Island Pines, the vessels have double, triple, and sometimes quadruple,
rows of discs, of smaller size than in the common pines; and in the
double series, these bodies are always arranged alternately (_Wond._ p.
696. _Bd._ 56 _a_.); Mr. Nicol states that there are about 50 discs in
the length of 1/20 inch, the diameter of each not exceeding 1/1000 inch.
The form and arrangement of these ducts, and the structure of the
medullary rays, are the characters on which the scientific botanist
relies for the detection of the affinities of the coniferous trees,
whose mineralized trunks and branches, in a fragmentary state, are, for
the most part, the only relics of these important tribes of the lost
floras of the earlier ages of our planet.[136]
[136] I know not a more delightful and instructive branch of science for
the young and inquiring of both sexes, than this department of Fossil
Botany, which the recent improvements in the microscope have rendered
so accessible; and yet there are but few cultivators of fossil botany
in England!
The great value of these data will be shown in the sequel.
* * * * *
The stems, fruit, and foliage, of Coniferæ, occur in the various
fossiliferous deposits, from those containing the earliest traces of
terrestrial vegetation to the newest tertiary strata; and a large
proportion of the petrified wood found in the British formations
belongs to trees of this order. The presence of rows of ducts on the
ligneous fibres, which is peculiar to this division of gymnosperms,
as we have already explained (_ante_, p. 58), is so easily detected
by microscopic examination, that the merest fragment of fossil
coniferous wood retaining internal structure, may without difficulty
be recognized. The number of rows, and the opposite or alternate
arrangement of the areolæ, are characters which, in the living pines
and firs, enable us to refer the respective trees to European or exotic
forms; but in the fossil coniferous wood, much diversity exists in
other not less important points of structure, and for the successful
cultivation of this department of fossil botany, works especially
devoted to the subject must be consulted. To the English student, Mr.
Witham's beautiful volume, "Observations on the Structure of Fossil
Vegetables, Edinburgh, 1831," will be found a valuable guide.
[Sidenote: FOSSIL CONIFEROUS WOOD.]
Fossil Coniferous Wood.--The coniferous wood of the secondary
formations of England, belongs for the most part to the Araucarian
type: that is, the glands, when in double rows, are placed alternately,
as in the Norfolk Island Pines (_Wond._ p. 696), and not side by side,
as in the common European species of firs and pines (_Bd._ p. 486).
Numerous sections of this kind of fossil wood are figured by Mr.
Witham, from specimens obtained from Lennel Braes, on the banks of the
Tweed, near Coldstream; and from near Allanbank Mill, in Berwickshire
(_Obs. Foss. Veg._ p. 14); a fossil trunk, 40 feet long, discovered in
Craigleith Quarry, near Edinburgh, at a depth of 136 feet, possessed
the same structure.
Palæoxylon (_coniferous wood of the Coal Measures_).--The existence of
coniferous trees in the Carboniferous flora, and the fact that their
trunks and branches had contributed to the formation of coal, was first
discovered and clearly demonstrated by Mr. Witham in the work to which
reference has been made. Figures of the peculiar structure observable
in thin slices of coal, are given in _Obs. Foss. Veg._ pl. iii. iv. v.
This carbonized wood resembles that of the Araucariæ in the multiple
series of ducts, and their alternate arrangement; but the presence of
thick compound medullary rays in these stems,--a character unknown in
any living conifers,--led M. Brongniart to place them in a separate
genus--_Palæoxylon_ (ancient wood); characterized by the presence
of medullary rays formed of numerous layers of cells, which are not
arranged in superimposed series, and that present a lanceolate or oval
form, in a section perpendicular to their direction.[137]
[137] The _Pinites Withami_, and _P. medullaris_, of Lindley and Hutton,
figured in Mr. Witham's work, belong to this genus. It may interest the
reader to know that slices of these woods prepared for the microscope
by Mr. Nicol, (presented to me by the late Dr. Henry, of Manchester,)
not only expose the vegetable organization in an admirable manner, but
also form beautiful objects for the exhibition of polarization.
Peuce.--Another species of coniferous wood from the coal is thus named;
it differs from the former in the medullary rays being composed but of
one layer of superposed cells.
Araucarites (_Dadoxylon of Endlechen_).--This term is employed to
designate the fossil wood whose structure is apparently identical
with that of the living species of Araucariæ, having the same kind
of medullary rays, and the ligneous fibres studded with discs or
areolæ, which are polygonal, often hexagonal, and disposed in several
alternating series. This wood is common in the Lias, Oolite, Wealden,
and Chalk.
Drifted fragments of coniferous wood of this type occur in the
Stonesfield slate, associated with leaves and fruits of cycadeæ,
and with marine shells, bones of reptiles, fishes, and mammalia; at
Scarborough, with the ferns and zamiæ previously described; at Swindon,
in the Portland oolite, with belemnites, ammonites, trigoniæ, &c.
[Sidenote: STERNBERGIA.]
Sternbergia.--To the Araucarian tribe, according to the recent
investigations of Professor Williamson, must be referred certain
fossil stems found in the coal-measures, and named _Sternbergiæ_.[138]
These are long solid cylindrical casts of sandstone or clay, with
annular constrictions, which are generally invested with a thin film
of carbonaceous matter; when this crust is removed the surface is
found to be marked with longitudinal ridges. These fossils were once
supposed to be the stems of plants allied to Yucca or Dracæna; but,
as was first shown by Mr. Dawson and Mr. Dawes,[139] they are merely
sandstone casts of the medullary axis or cylinder of an extinct genus
of coniferæ, allied to the Araucariæ: a specimen in which the cast was
surrounded by a thick ligneous cylinder, heaving enabled that acute
observer to detect the structure of the original.[140] The Sternbergiæ
are sandstone casts of central cavities existing within the true pith;
which cavities, under some favourable conditions, were filled with
inorganic materials. Mr. Williamson is inclined to believe that all
the coniferous wood from the coal-measures, belonging to the genus
_Dadoxylon_, is referable to the trees of whose piths the _Sternbergiæ
approximatæ_ are internal casts; and that some of the foliaceous
appendages of these trees have been confounded with Lepidodendra.[141]
[138] See Pictorial Atlas, pl. xviii. p. 53.
[139] On the Coal formation of Nova Scotia, Geol. Proc. 1846.
[140] See Prof. Williamson's Memoir on Sternbergia, Manchester Philos.
Trans. 1851.
[141] Ibid. p. 355.
Petrified Forests of Conifers.--The most remarkable assemblage of
fossil conifers is that presented in the well-known quarries in the
Island of Portland, to which allusion was made when describing the
Mantelliæ obtained from that locality (_ante_, p. 157). Referring to
_Wond._ p. 385,[142] for an account of the geological circumstances
under which the phenomena occur, it will suffice to state that a
forest of pines appears to have been submerged, and the trunks to have
become petrified, whilst standing erect on the spot where they grew;
the Cycads still shoot up as it were between the stems, and the roots
of the trees, though changed into flint, extend into the bed of mould
whence they originally derived support, and which is so little altered
in appearance, as to be called the _Dirt-bed_, by the quarrymen; thus
realizing the fable of the petrified city in Arabian story, whose
inhabitants were turned into stone, in the varied attitudes of life.
[142] Geol. I. of Wight, p. 394. Petrifactions, p. 56.
No foliage has been observed in connexion with these trees; not a leaf
has been found in the rocks: a cone, nearly related to the fruit of
Araucaria excelsa, was discovered in the Dirt-bed.
At Brook-point, in the Isle of Wight, an equally interesting fact may
be observed. At the base of the cliff, which is entirely composed of
Wealden clays, shales, and sandstones, there is a vast accumulation of
petrified firs and pines, imbedded in the indurated grit that forms
the lowermost strata on the sea-shore, and of which the reefs and
rocks, produced by the encroachments of the sea, and that extend far
from land, are composed. These can be examined at low-water, and the
observer, upon lifting up the fuci and algæ which cover them, will
find the rocks and masses of stone to consist of petrified trunks of
coniferæ. There are no erect trees as in Portland; on the contrary, the
stems are prostrate, and lie confusedly intermingled, and associated
with bones of Iguanodons and other reptiles, and large mussel-shells;
the whole presenting the characters of a raft of forest trees which had
drifted down the stream of a vast river, and entangled in its course
the limbs and carcasses of animals that were floating in the water, and
the shells that inhabited the river, and at length became submerged in
the bed of the delta or estuary. Both foliage and fruit have been found
in the Wealden deposits at Brook, and will be described hereafter.[143]
[143] See Geol. I. of Wight, chap. x. and xi.
In the sands of the Desert of Sahara, in Egypt,--among the mammalian
bones of the Sub-Himalayas,--and in the tertiary deposits of Virginia
associated with cycads,--drifted trunks of conifers have been
discovered.
Fossil trees of this family also occur in various localities in
Australia and Van Diemen's Land, the wood of which is in some parts
calcified, and in others silicified. The same trunk often has
externally a white friable calcareous zone, several inches thick,
traversed by veins of silex, or opaline chalcedony, while the centre
is a silicified mass; in both states the internal structure may be
detected. This kind of fossil wood is to be seen in most cabinets, a
large quantity having been sent to England by emigrants.[144] These
fossil trees appear to have been subjected to the same mutations as
those of the Isle of Portland, for they are described as standing erect
to the height of several feet in a bed of arid sand, apparently in the
places where they grew; their petrified branches being scattered around
them. They so entirely preserve their natural appearance, that one of
the colonists mentions among the extraordinary sights he witnessed on
his first arrival in New Holland, the burning of trees into lime to
manure the ground.
[144] My late friend, Sir Francis Chantrey, had a magnificent specimen,
which, is now in the British Museum. See Petrifactions, p, 59.
[Sidenote: FOSSIL CONIFERÆ OF AUSTRALIA.]
A fossil pine forest, on the eastern coast of Australia, in the
inlet called Lake Macquarrie, is described by the Rev. B. Clarke, as
occurring at the base of a mountain range, composed of conglomerate and
sandstone, with subordinate beds of lignite; an alluvial plain extends
to the water's edge, covering the sandstone rock which is seen _in
situ_ beneath. Throughout this plain, stumps of fossil trees project
from the ground, and present the appearance of a forest in which the
trees have all been broken off at the same level. At the distance of
some yards from the shore, a reef is formed by vertical rows of the
petrified stems, which project out of the water. Many of the fossil
stems on the strand have the remains of roots extending into the
sandstone below the alluvial deposit, and, like those in the Island of
Portland, are in some instances surrounded by an accumulation of rock,
which forms a mound of a higher level than the surface of the stratum.
The trunks are, generally, three or four feet high, and from two to
six feet in diameter. The wood is silicified, and veins of chalcedony
traverse its substance between the concentric rings and medullary rays;
in several examples, from 60 to 120 annual circles of growth were
observable. Beds of lignite occur in the neighbouring hills, both above
and below the fossil trees; many localities along the eastern coast of
Australia are mentioned, as presenting similar phenomena. I may add
that the only fragment of petrified wood found by Mr. Walter Mantell in
New Zealand is coniferous.
In the valley of the Derwent, in Australia, opalized coniferous
trees of a similar character were observed under very extraordinary
circumstances, by the distinguished traveller, Count Strzelecki.
Truncated stems were found standing erect in a bed of scoriaceous
basalt (lava) and trachytic conglomerate: but in some instances only
basaltic casts of the trunks remain. This curious phenomenon can
only be explained by supposing the silicified stems to have resisted
the intense heat of the incandescent lava, while trees placed in
circumstances unfavourable to their petrifaction were consumed: but
the latter, being either saturated with water, or fresh and green,
were burnt slowly, and left cylindrical moulds in the cooled basaltic
scoriæ, with impressions of the external surface of the bark; these
moulds were filled Tip by a subsequent eruption, and thus basaltic
casts of the consumed trees were formed.[145]
[145] Physical Description of New South Wales, by Count Strzelecki.
Coniferous Wood in Oxford Clay.--It would occupy too much space to
notice the numerous localities in which fossil remains of conifers
occur in the Liassic and Oolitic formations of England.
In the Oxford and Kimmeridge Clays water-worn trunks and branches of
large pine-trees are often met with. An interesting deposit of these
remains was brought to light by my youngest son (Mr. Reginald Mantell),
when constructing the branch line of railway from the Great Western to
Trowbridge, in Wilts. In the progress of the work, extensive sections
were cut through the Oxford Clay, and laid bare a large quantity of
drifted wood, much of which was not petrified, but in the state of
bog-wood, and was used for fuel by the workmen. Trunks ten or twelve
feet long were met with, to which serpulæ, oysters (_Ostrea delta_),
and other shells were adherent. These vegetable remains were associated
with Belemnites, Belemnoteuthides, Ammonites, &c.; and had evidently
been drifted far out to sea by currents.[146]
[146] See _Wond._ p. 502. Geol. Journal, vol. vi. p. 311.
[Sidenote: FOSSIL CONIFEROUS WOOD.]
Coniferous Wood in the Chalk formation.--The arenaceous limestones
of the Greensand of Kent and Sussex abound, in some localities, in
water-worn masses of coniferous wood, which are often perforated by
boring mollusks, as _Teredo_, _Fistulana_, _Gastrochæna_, &c. In the
Iguanodon quarry of Kentish rag, near Maidstone, large quantities
of these remains occur, and Mr. Bensted has collected several cones
belonging to different kinds of conifers; one of these appears to be
a species of _Abies_, or Fir:[147] it was associated with fragments of
trunks and branches, whose internal structure proved their relation to
the fruit. _Plate V. fig. 2_, are microscopic views of transverse and
longitudinal sections of this wood; 2_a_ shows the cellular tissue in
a transverse slice, seen by reflected light; 2_b_ a vertical section
in the direction of the medullary rays, exhibiting the vessels studded
with single rows of glands. This wood occurs both in a calcareous and
siliceous state; in some examples the external zones are calcareous,
and the inner siliceous; in others the entire branch is changed into
black flint, in which the coniferous structure is beautifully preserved.
[147] It is figured and described as _Abies Benstedi_, by the Author.
Geol. Proc. January, 1843.
Near Willingdon, in Sussex (_Geol. S. E._ p. 172), a bed of sand,
immediately beneath the Galt, contains a layer of water-worn fragments
of stems and branches, of small size; they are generally perforated by
_Gastrochænce_, and the cavities formed by these depredators are filled
with particles of green chlorite sand. The structure of this wood is
represented in _Plate V. fig. 3^a_ a transverse, and 3_b_ a vertical
section, viewed by reflected light; in 3_b_ the vessels are dotted
with two parallel longitudinal rows of very minute glands, arranged
alternately, as in the Araucariæ; a fragment of one of the medullary
rays is seen near the middle of the specimen.
In this deposit of coniferous wood, two or more fruits apparently
referable to _Zamiæ_ have been discovered; one specimen, five and
a half inches long, and of an elongated cylindrical form, covered
with rhomboidal eminences, I have figured and described as _Zamites
Sussexiensis_.[148]
[148] Geol. Proc. 1843.
[Illustration: Lign. 58. Fragment of Coniferous Wood in Flint.
_From a wall in Lewes Priory,_]
The White Chalk of England has afforded but few traces of plants of
this family. Fragments of coniferous wood are, however, occasionally
found in the state of carbonaceous, or reddish brown friable masses,
and when this substance is removed, the surface of the chalk is seen to
be marked with impressions of ligneous fibres; sometimes the surface
is studded over with little pyriform eminences, which are cretaceous
casts of perforations made by insects in the wood. These specimens,
when all traces of the wood are absent, are very puzzling to those who
are not aware of their origin.
Occasionally silicified fragments of wood are found imbedded in flint.
I have an interesting specimen of this kind obtained from a wall in
Lewes Priory (_Lign. 58_), and though it must have been exposed to the
influence of the weather for nearly eight centuries, its surface still
exhibits coniferous structure.
[Sidenote: WOOD IN FLINT.]
Tertiary Coniferous Wood.--The Tertiary formations in some localities
abound in coniferous plants and trees, which, in the Paris basin,
are associated with bones of mammalia; several species of pine
(_Pinus_) and of yew (_Taxus_) from those deposits are described by M.
Brongniart. I have collected fossils of this kind from the London Clay
of the Isle of Sheppey, Bracklesham Bay, and Bognor in Sussex, and Alum
Bay, in the Isle of Wight; and from the plastic clay at Newhaven.
Fossil Foliage and Fruit of Conifers.--From this digression on the
pine-forests and drift-wood of the secondary formations, we return to
the examination of the foliage and fruits of this order of vegetables
that are preserved in the mineral kingdom.
Araucaria peregrina (_Lindley and Hutton_). _Lign. 59, fig.1._--With
the trunks and branches of conifers of the Lias, cones and foliage
are occasionally found: a beautiful example of a branch with the
leaves preserved, is figured, _Lign. 59_. This fossil has been so
admirably cleared from the shale which invested it (by Miss Philpot)
that even the surface of the leaves is exposed. It so closely
resembles a twig of _Altingia excelsa_, that the eminent authors of
Foss. Flor. have named it as above. But M. Brongniart states that the
foliage differs from that of the two living groups of Araucariæ: in
_Araucaria Brasiliensis_, the leaves are flat, in _Altingia excelsa_,
quadrangular; in the fossil the leaves are short, fleshy, arranged
spirally, and inserted.
[Illustration: Lign. 59.
Fig. 1.--Part of a Branch of Araucaria peregrina; _nat._
_Lias, Lyme Regis._
2.--Calamites nodosus with foliage; _nat._ _Coal-shale_,
(see _ante_, p. 109).
]
Pinites; a name applied to those fossil leaves and fruits which agree
in their general character with the recent genus Pinus; upwards
of thirty species are known.[149] In the Pines, as botanically
distinguished from the Firs (_Abies_), the leaves arise in bundles
of from two to five; and the scales of the cones are thickened, and
terminate in discs more or less defined. In Firs, (Larch, Cedar, &c.)
the scales have thin edges, and the leaves are solitary.
[149] See Endlechen's Synopsis Coniferarum.
Pinites Fittoni. _Geol. Isle of Wight_; 2d edit, p. 457.--Several cones
with the above characters have been found in the Wealden formation. A
cone figured and described by Dr Fitton, is remarkable for a double
prominence on each scale: It was supposed to resemble the fruit of
_Dammara_, but the strobilus of the latter is like that of the Cedar of
Lebanon, in which the edges of the scales are thin. The Wealden fossil
appears to be a genuine pine, and may be distinguished by the name of
its discoverer, _Pinites Fittoni_; a small figure of the only known
specimen is given, _Wond._ p. 399, _fig._ 4.
I have collected from the Wealden strata of the Isle of Wight three or
four small cones, which resemble those of a species of Araucaria; they
are ovate, imbricated, with acuminated scales, which are recurved at
the apex. The fossils figured in _Wond._ p. 399, _figs._ 2 and 3, are,
I believe, water-worn specimens of the same species.[150]
[150] I subjoin a definition of the genera Pinus and Abies, for the use
of the student.
Pinus.--_Fruit_-catkins ovate, roundish, or cylindrical closely set
with thick two-flowered scales; forming an imbricated cone, composed of
numerous ligneous angular, or flat, rigid scales, having attached to
the inside of each two seeds crowned with a thin membraneous, falcate,
oblong, or roundish wing; the scales are composed of a thick woody
substance, forming an angular surface, with a recurved point. The Pines
are evergreen trees, with from two to five narrow, angular leaves
springing from each sheath. Cotyledons four to twelve.
Abies.--Cones with thin flat scales, which are more membranous at the
extremities than in Pines: the leaves are emarginate, short solitary,
needle-shaped, angular or flat.
[Sidenote: WALCHIA.]
Walchia. _Lign. 60._--The fossil coniferæ thus named by Sternberg,
have numerous closely set, regularly pinnated branches, resembling
those of _Araucaria excelsa_, and which are thickly beset with foliage.
The leaves are sessile, compact, enlarged at the base, tetragonal
or falciform, and slightly decurrent; they often vary considerably
in form and length on the same bough. The branches are in some
examples terminated by oblong cones, composed of imbricated, oval or
lanceolate, pointed scales, the summits of which are not recurved,
as in the Araucariæ. The trees of this genus are closely related to
the _Araucaria excelsa_, and _A. Cunninghami_. Some species occur in
the Coal formation at St. Etienne and Autun;[151] others (as _Walchia
hypnoides_) in the schists of Lodève, and in the copper slates of the
Zechstein in Mansfeld.[152]
[151] "Mines de Houille de Vettin, &c." See "Tableau des Vég. Foss." p.
70, par M. Brongniart.
[152] Missing!
[Illustration: Lign. 60. Walchia hypnoides; 1/3 _nat._
_Permian, Lodève_.
Part of a bough with six of the branches bearing terminal cones.]
Abietites.--To the Abies, or Fir, several cones found in the Wealden
deposits of Sussex and Hants closely approximate in the form and
structure of their scales. The most remarkable is the very elongated
coniferous fruit, first discovered by me in the Wealden at Brook Point,
and described and figured in my Geology of the Isle of Wight (_2d
edit._ p. 452), under the name of _Abietites Dunkeri_, in honour of
the eminent geologist who has so successfully and diligently explored
the Wealden of the North of Germany.
I have been so fortunate as to collect from thirty to forty specimens
of these fruits of the conifers of the country of the Iguanodon,
associated with trunks and branches, and imperfect vestiges of single
lanceolate leaves.
[Illustration: Lign. 61.
Abietites Dunkeri.
_Wealden; Isle of Wight;_
1/3 _nat._
Fir-cone, showing the imbricated scales, and many bracteæ.]
[Sidenote: ABIETITES DUNKERI.]
Abietites Dunkeri. _Lign. 61._--These cones are of a cylindrical form,
and greatly elongated: the largest specimen is thirteen inches in
length, and but three inches in circumference. The scales are broad,
slightly convex without and concave within, obovate or subrotund, with
a prominent midrib, edges thin and entire. Leaves solitary, slender,
slightly curved, from 1 inch to 1-1/2 inch in length. The cones
were garnished with bracteæ, which are seen on the margins of the
fossil when imbedded in the rock. Whether the foliage that forms the
constituent substance of a large proportion of the bituminous coal of
Hanover (_ante_, p. 74), and which has been figured and of the named
by Dr. Dunker _Abietites Linkii_, belongs to the same species of Fir
as these cones, I am unable to determine. The seeds are of an ovate
form: the pericarp is in the state of carbon, and filled or lined with
pyrites or calc-spar.
These cones are generally found more or less pyritified, and are
extremely beautiful objects when first collected; but like the fruits
from the Isle of Sheppey, similarly mineralized, often decompose, in
spite of every precaution, after exposure to the air but for a few
weeks.
A small sub-ovate fir-cone found with coniferous wood in the
Kentish-rag of Mr. Bensted's quarry, near Maidstone, (_ante_, p. 173),
and figured and described by me as _Abies Benstedi_, probably belongs
to the coniferæ of the Wealden, since it was associated with drifted
bones of the Iguanodon.
Fossil Cypresses.--The tribe of conifers called _Cupressus_ or Cypress,
(distinguished from the firs and pines by the leaves being mere scales,
and the cones consisting of small wooded peltate bracteæ, and by other
botanical characters,) including the Juniper and Arbor-vitæ, appears to
have flourished during the whole of the secondary epochs; for fossil
leaves and stems referable to this family, but whose generic affinities
cannot be determined with precision, have been found in the Trias,
Lias, Oolite, and Wealden deposits.
[Illustration: Lign. 62.
Thuites Kurrianus _nat._
_Wealden. Hastings._]
Thuites Kurrianus. _Lign. 62._--The _Thuja_ or Arbor-vitæ, a plant too
well known to require description, is the type of the fossil plants
distinguished by the name of _Thuites_. Many years since I discovered
vestiges of branches and leaves of some species of this genus, in the
ironstone of the Wealden beds, at Heathfield in Sussex (_Geol. S. E._
p. 228); and of late, many specimens have been found in strata of
the same formation in England and Germany. The branch here figured,
from the cabinet of S. H. Beckles, Esq. will serve to illustrate
the appearance of these fossil plants. Some small fruits found in
the ironstone of Heathfield may possibly belong to Cypresses. The
foliage and fruit of five or six distinct species of Thuites have been
discovered in Tertiary strata.
Voltzia.[153] (_Wond._ p. 547).--This extinct genus of plants is
peculiar to the Trias (_Grès bigarré_) or New Red deposits, and is
one of the most characteristic of the fossil coniferæ. The specimens
first found were from _Sultz-les-Bains_, near Strasburgh. The leaves
are alternate, arranged spirally, sessile, and decurrent, and have
much analogy with those of certain Araucariæ. The fruits are oblong
cones, with cuneiform scales, slightly imbricated, not contiguous, and
generally with from three to five lobes.
[153] Named in honour of the late M. Voltz, of Strasburgh, by whom they
were first discovered. The specimens in the British Museum, from my
collection, were presented to me by M. Voltz.
[Sidenote: TAXITES. NŒGGERATHIA. FOSSIL RESINS.]
Taxites.--Some branches found in the Stonesfield slate, and bearing a
general resemblance to twigs of Yew (_Taxus_), are described under the
above name, but their analogies are doubtful. (See _ante_, p. 145.)
Nœggerathia.[154]--I must briefly notice the coal-plants which M.
Brongniart has placed under this genus, because the foliage of some
species appears to have entered largely into the formation of certain
seams of coal, although the perfect form of the leaves is unknown.
The foliage referred to Nœggerathia consist of pinnated, or deeply
pinnatifid, simple leaves. These leaves, or leaflets, are either
elongated, linear, lanceolate, wedge-shaped or flabelliform, and
entire, or deeply lobed at their extremity, and are traversed by
numerous, fine, equal nerves, slightly diverging from the base, but
almost parallel. The affinities of these plants are not satisfactorily
made out: M. Brongniart considers them to approach nearest to the
Cycads or Conifers; perhaps forming a connecting tribe between those
two great groups of gymnosperms.[155]
[154] A leaf of _N. flabellata_ is figured in Foss. Flor.
[155] Tab. Veg. Foss. p. 64.
Fossil Resins.--Amber.--The resinous secretions of Conifers are
occasionally found in a fossil state. When the tunnel was carried
through Highgate Hill, in 1811, concretionary lumps of a brittle
substance were discovered, which proved, upon analysis, to be the
resin of a coniferous tree changed by mineralization. In a bed of
fossil wood, near Hythe, in Kent, a resin was found that partook
of the properties of amber and retinasphalt; it was of a clear red
colour, very infusible, and acted upon with difficulty by many chemical
solvents.[156]
[156] Geological Proceedings, 1843.
The pollen of pines or firs occurs in a tertiary deposit at Egra, in
Bohemia; this bed is entirely composed of pollen and the frustules of
many kinds of diatomaceæ.[157]
[157] Described by M. Ehrenberg.
[Sidenote: AMBER. FOSSIL PALMS.]
_Amber_, so remarkable for its electrical properties, and so largely
used for ornamental purposes, is a fossil resin, the product of an
extinct species of pine (_Pinus succinifer_), which, though nearly
allied to _Pinus abies_, and _P. picea_, is essentially distinct.
The Amber in the European markets is principally collected from the
shores of the Baltic, between Memel and Konigsberg, being washed out of
submerged beds of lignite, and thrown up on the strand by the waves.
Amber is occasionally found on the eastern and northern shores of
England. The forests of Amber-pines appear to have been situated in
the south-eastern part of what is now the bed of the Baltic, in about
55° north latitude, and 37° to 38° east longitude, and were probably
destroyed at the commencement of the Drift period.
Insects, spiders, small crustaceans, leaves, and fragments of vegetable
tissue, are often imbedded in amber; and a few hairs and feathers of
mammalia and birds have been detected. These organic bodies must have
become immersed in this substance when it exuded from the trees in a
viscid state, for they are often preserved as fresh and beautiful as
if recently embalmed in the liquid resin. Upwards of 800 species of
insects have been discovered, chiefly referable to Aptera, Diptera,
Neuroptera, Coleoptera, Libellula, &c.: by far the greater number
belong to extinct forms.
The vegetable remains comprise four species of pine, and species of
cedar, cypress, juniper, yew; and of oak, poplar, beech, ash, &c.; and
a few ferns, mosses, liverworts, confervæ, and fungi. The Amber appears
to have exuded from the bark and wood, but chiefly from the root-stock,
as is the case with the _Copal_ and _Animé_, which are resinous
substances obtained from certain trees in India and America, and
largely employed for varnish: these resins are often substituted for
true amber, especially when they contain insects, &c.; but the latter
are always of the existing indigenous species of the country. The
difference observable in the colour of the various species of amber, is
attributable to accidental chemical admixtures.[158]
[158] Petrifactions, p. 23.
Fossil Palms (_Palmacites_).--Reserving an account of the fossil
plants belonging to the other grand division of Dicotyledons, the
_Angiosperms_ (_ante_, p. 61), for the last section of the present
chapter, I proceed to notice the most important family of the
_Endogens_, or _Monocotyledons_, whose remains occur abundantly in many
tertiary deposits--the Palms.
The Palms are, for the most part, lofty trees, having a single
cylindrical stem, which, like that of the arborescent ferns, rises to
a great height, and is crowned with a canopy of foliage. The trunks
are solid, most dense on the outer part, and in some species (as the
Cane-palms) are coated with a thin siliceous epidermis. At a little
distance above the surface of the ground, strong, simple, rope-like
roots are sent off from the stem, appearing like clusters of stays or
braces to support the trunk; and the base of the petrified palm-trees
often exhibits vestiges of these organs.[159] The leaves are supported
by petioles, and are in most species very large;[160] they are either
pinnated or flabellated (fan-shaped), and sometimes nearly split
in half: the veins or nervures are parallel, and the interspaces
plaited like the folds of a fan. The surface of the stem is scored
by transverse scars formed by the separation of the petioles, and
these markings assist in the identification of the fossil trunks
of palm-trees. The fruit is in some kinds a single drupe, as the
Cocoa-nut; in others a cluster of soft pericarps, as the Date.
[159] Specimens in the Brit. Mus. Petrifactions, p. 12.
[160] In the Fan-palm (_Corypha_), the leaf is sometimes twenty feet
broad.
The Palm family is divided into upwards of sixty genera, comprising
more than a thousand species: the greater number are inhabitants of
tropical countries. Stems, with the external surface and internal
structure preserved, and the foliage, and fruit, of several kinds of
Palms, have been found in a fossil state, and chiefly in the Tertiary
formations. Examples of the large silicified palm-stems from the
West India Islands, where they occur imbedded with corals petrified
in the same manner, are to be seen in the British Museum,[161] and
most public collections: and sliced polished sections, exhibiting
the monocotyledonous structure, are common in private cabinets. The
endogenous organization of the stems is so obvious as to leave no doubt
as to the class to which the trees belong, but M. Brongniart states,
that, in the absence of the foliage and fruit, it is seldom possible to
pronounce with certainty that a fossil monocotyledonous stem belongs to
a Palm; for the internal structure alone does not enable the botanist
to fix upon any characters which will distinguish the stems of Palms
from those of Pandanus, Agave, Yucca, Aloes, Dracæna, &c. Fossil
monocotyledons known by their stems only, are therefore arranged by M.
Brongniart under the general name of _Endogenites_.
[161] Petrifactions, p. 52.
The _Palmacites carbonigenus_ of Corda, and other supposed palm-trees
of the Coal formation, are regarded by the same eminent botanist as
essentially differing in structure from this family, and belonging to
an extinct tribe of exogens.
That a large proportion of the exogenous stems found in the Tertiary
deposits are true palms, there can, however, be no doubt, for the
foliage and fruit, which are occasionally associated with them, confirm
the inference drawn from the characters of the trunks.
[Sidenote: FOSSIL PALM LEAVES.]
Stems, leaves, and fruits of Palms have been discovered in the Paris
basin, by M. Ad. Brongniart (_Bd._ pl. lxiv. p. 515); and silicified
trunks in many other places on the Continent; but no fossils of this
kind surpass in beauty and interest those which are found in the West
Indies. A slice of a silicified stem from Antigua is represented, as
seen by reflected light, in _Plate V. fig. 1_; it admirably displays
bundles of vessels imbedded in cellular tissue.
Silicified stems of monocotyledons, related to the Palms, are very
widely distributed, and have been collected among mammalian remains in
Ava, and in the Sub-Himalaya mountains.
Fossil Palm-leaves.--The pinnated and fan-shaped leaves of the Palms
are so peculiar as to be easily recognized in a fossil state. Though
many specimens have been found in the tertiary strata of the Continent,
but two or three examples have been met with in England. The first
discovered British specimen is in my cabinet, and was obtained by
Mr. Fowlstone, of Ryde, from the fresh-water limestone of Whitecliff
Bay, in the Isle of Wight. It is thirteen inches in length, and
eleven in width: fresh-water shells and plants are imbedded with it.
It is figured in Geol. I. of Wight, _2d edit._ p. 431. This species
(_Palmacites Lamanonis_) occurs also at Aix in Provence, in great
perfection, associated with Insects, Fishes, fresh-water shells, &c.
(_Wond._ p. 260. _Petrif._ p. 62).
Twelve species of palm-leaves are enumerated by M. Unger, from the
Tertiary deposits of the Continent. One species has been found in
the Chalk formation of Silesia; the most ancient strata in which the
remains of undoubted palms have as yet been observed.
The fossil palm-leaves of the pinnated form are named _Phœnicites_,[FF]
and examples occur in the Tertiary grits of Puy en Velais, I am not
aware that leaves of this type have been found in England: diligent
research in our tertiary leaf-beds (at Whitecliff Bay, Alum Bay,
Bournemouth, Wareham) will probably sooner or later discover them. The
leaflets have a well-marked median nerve, with fine nervures running
parallel with it; a character by which the foliage of _Phœnicites_ may
be distinguished from that of the Cycadeæ.
[162] From _Phœnix dactylifera_: the Date-Palm.
Fossil Fruits of Palms.--Although certain fruits found in the
coal-measures have been referred to the palm-tribe by M. Unger, Dr.
Lindley, and other botanists, M. Brongniart is of opinion that no such
identification can be established; the same remark applies to the
Carpolithes from the Oolite; in fine, the Tertiary deposits have alone
yielded fruits that can be unquestionably referred to plants of this
order. The most productive British locality of fossil fruits of Palms,
and of many other vegetables, is the Island of Sheppey; and I purpose
describing in this place, not only the remains of this family, but also
of the other plants associated with them.
[Sidenote: FOSSIL FRUITS OF THE ISLE OF SHEPPEY.]
Fossil Fruits of the Isle of Sheppey.--This little island, which is
situated in the mouth of the Thames, is entirely composed of the
London Clay, with bands of septaria. On the north, there is a range
of cliffs, about two hundred feet high, which is being continually
undermined by the waves, and large masses of the clay are thrown down,
and innumerable fruits, seeds, branches and stems of trees, and other
fossils, are exposed on the strand at low-water. The vegetables are
strongly impregnated with iron pyrites, and as this mineral speedily
decomposes when exposed to the atmosphere, the choicest examples often
fall to pieces, even when preserved in the cabinet.[163] The nodular
masses of indurated clay, termed septaria, contain the best preserved
and most durable fossils. The fossil fruits, or carpolithes, occur
in such profusion, that a large collection can easily be made; they
comprise several hundred species, few of which have been scientifically
investigated.[164]
[163] Mr. Bowerbank, who possesses an unrivalled collection of these
fruits, keeps them in stopper-bottles filled with water, placing
the different species separately, and labelling the phials. I have
successfully employed mastic varnish, first wiping the specimens dry,
and removing any saline efflorescence by means of raw cotton, and then
brushing in the varnish with a stiff hair-pencil.
[164] See vol. ii. Excursion to the Isle of Sheppey.
Mr. Parkinson has given admirable figures of several of the Sheppey
fruits, particularly of the large palm-like nuts, called "_petrified
figs_" (_Org. Rem._ vol. i. pl. vi. vii. _Pict. Atlas_, pl. vi. vii.)
M. Ad. Brongniart has named several in his _Prodrome_; but without
figures the descriptions are useless to the student. Mr. Bowerbank
has published two numbers of a work entitled, "_History of the Fossil
Fruits of the London Clay_," with seventeen plates; from which I have
selected a few subjects for illustration. The fruits described are the
following:
1. Fruits having a downy structure, like the Cotton plant.
2. _Cucumites._ Seeds of plants of the cucumber family. _Lign._
63, _fig._ 1 and 3. These fossil fruits so closely resemble
the seeds of various members of the recent genus _Cucumis_,
or Cucumber, comprising the Gourd, Water-melon, &c., both in
outward form and internal structure, that there is no reasonable
doubt of their belonging to plants of the same family; hence the
name _Cucumites_ or fossil cucumbers.
3. Cones of a tree allied to the genus _Petrophila_, of New
Holland. _Lign._ 63, _figs._ 2 and 8.
4. Seeds of the Bean family, some of which resemble those of the
common Scarlet-runner. _Lign._ 63. _figs._ 5, 6, 7.
5. _Wetherellia_; pulpy fruits divided into two lobes by the
expansion of the ripe seeds. As the section thus exposed bears
some resemblance to a coffee-berry, these fossils are popularly
called petrified coffee-berries. This genus has no known living
representative. _Lign. 63, fig. 4_.
6. Fruits allied to the Palm tribe. (_Nipadites_). _Lign._ 63,
_fig._ 9, and 10.
7. Fruits of leguminous plants, differing from any known recent.
_Lign._ 64, _figs._ 1, 2, 3, 4.
8. Seeds, allied to the _Amomum_, or Cardamom tribe. _Lign. 64,
fig. 5_.
9. Seeds of _Cupressinites_, or plants related to the Cypress.
10. Seeds resembling those of the _Laburnum_.
11. Seed-pod of a species of _Acacia_, or _Mimosa_. _Lign. 64,
fig. 7._--2/3 _nat._
[Illustration: Lign. 63. Fossil Fruits from the Isle of Sheppey.
_London Clay._
Fig. 1 and 3.--_Cucumites variabilis_: fig. 3, is a vertical section,
showing the seeds. _Lign._ 64, fig. 6--1/2 _nat._
2 and 8.--_Petrophiloides Richardsoni_: 1/3 _nat._ Fig. 8, is a
vertical section, showing the disposition of the seeds in the
cells formed by the confluent scales--1/2 _nat._
4.--_Wetherellia variabilis_: a section of the fruit, in which state
it is called coffee-berry by the collectors--1/3 _nat._
5 and 6.--_Faboidea semicurvilinearis_: fig. 5, side view--
1/4 _nat._
6.--Is the face of a similar seed--1/3 _nat._
7.--_Faboidea bifalcis_: side view--1/3 _nat._
9.--_Nipadites lanceolatus_: _a_, the seed; _b_, the shell, or
pericarp--1/2 _nat._
10.--_Nipadites cordiformis_: _a_, the extremity of the seed,
imbedded in the shell--1/3 _nat._
]
[Illustration: Lign. 64. Fossil Fruits from the Isle of Sheppey.
_London Clay._
Fig. 1 and 2.--_Zulinosprionites latus_. 2. A section, showing the
receptacles for two seeds.--2/3 _nat._
3.--_Leguminosites dimidiatus_; side view.--1/2 _nat._
4.--_Leguminosites subquadrangularis_; side view.--1/2 _nat._
5.--_Cupanoides lobatus._--1/2 _nat._
6.--_Cucumites variabilis._--1/2 _nat._
7.--_Mimosites Browniana_; from Ossington, Suffolk. A seed-pod of an
_Acacia_, or other plant of the _Mimosa_ family.--2/3 _nat._
]
Nipadites. _Lign. 63_. (_Pict. Atlas_, pl. vi. vii.)--The most
remarkable fruits in the above catalogue are those which, from their
appearance when compressed, are known to collectors by the name of
"_petrified figs_" (_Lign. 63, fig. 9, 10_). Some specimens attain
a considerable size, and are from five to seven inches long. The nut,
and the pericarp or shell, are often well preserved. These fossils were
referred to the _Cocos_ by Mr. Parkinson, but they have not a ligneous
endocarp with three pores as in the Cocoa-nut.
Mr. Bowerbank has shown that they are nearly related to the fruit of
the Nipa, or Molucca-Palm, a tree which abounds in Bengal, and in the
Molucca and Philippine Islands. The Nipæ are low, shrub-like plants,
having the general aspect of palms; they grow in marshy tracts, at the
mouths of great rivers, particularly where the waters are brackish.
They are allied to the Cocoa-nut tribe, on the one hand, and to the
_Pandanus_, or Screw-pine, on the other.
The _Nipadites_, according to Mr. Bowerbank, have the epicarp and
endocarp thin and membranous, and the sarcocarp thick and pulpy, and
composed of cellular tissue, through which run numerous bundles of
vessels. Nearly in the centre of the pericarp is situated a large
seed which, when broken, is more or less hollow. This seed consists
of regular layers of cells, radiating from a spot situated near the
middle, and apparently inclosing a central embryo.
The same author remarks, that "if the habits of the plants to which
the fossil fruits belonged were similar to those of the recent _Nipa_,
it will account for their abundance in the London Clay in the Isle of
Sheppey; which formation, from the great variety of stems and branches,
mixed up with star-fishes, shells of mollusks, and bones of fishes,
crustaceans, and reptiles of numerous marine and fresh-water genera,
is strikingly characteristic of the delta of a river, which probably
flowed from near the Equator towards the spot where these interesting
relics are deposited." The fact that the seed-vessels of several
species of Nipadites abound in the Isle of Sheppey, and have not been
observed in any other locality in England, tends to support this
opinion.
Carpolithes of this kind occur in great perfection in the Eocene
strata of Belgium, and were figured and described, nearly seventy
years since, in Burton's "_Oryctographie de Bruxelles_," as petrified
cocoa-nuts; the uncompressed state in which these fossils occur makes
the resemblance to the recent fruit more striking than in the flattened
pyritous specimens from the clay of Sheppey.
[Sidenote: NIPADITES OF BELGIUM.]
The _Nipadites_ of Brussels have recently been brought under the more
immediate notice of English geologists, in a memoir "On the Tertiary
Strata of Belgium and French Flanders," by Sir Charles Lyell, in
which several specimens are figured and described.[165] These fossils
are found in sands and sandstone, presumed to be of the age of the
Bracklesham beds of Sussex. They are procured from Schaerbeek, in the
northern suburbs of Brussels, where extensive quarries are worked for
paving-stones, and have long been celebrated for remains of turtles,
trunks of palms, and dicotyledonous trees, and the fruits, now called
Nipadites. The vegetable remains often occur silicified; Sir C. Lyell
was shown by the workmen "the trunk of a petrified exogenous tree, with
forty rings of annual growth; it had lain in a horizontal position, and
was bored by teredinæ. The silicified base of the trunk of a Palm-tree,
apparently broken off short at about the level of the soil, had
numerous air-roots, or rootlets, attached."[166]
[165] Quarterly Journal of the Geological Society of London, vol. viii.
August 1852.
[166] "On the Belgian Tertiary Formations," Geol. Journal, vol. viii, p.
344.
Of the thirteen species of Nipadites enumerated by Mr. Bowerbank,
some of which are, however, only accidental varieties, four have been
identified among those obtained from Schaerbeek: two of them belong
to but one species--the _Nipadites Burtoni_: the others are _N.
lanceolata_ (_Lign. 63, fig. 9_), and _N. Parkinsoni_ (_Pictorial
Atlas_, plate vii.). These fossil nuts closely resemble the fruit of
_Nipas fruticans_, a palm which abounds in the delta of the Ganges,
and other parts of Bengal, and is the only living species of the
genus known.[167] In an immature or abortive specimen of _Nipadites
giganteus_ (of Bowerbank), figured in _Geol. Journ._ pl. xix. fig. 2,
the angularity of the pericarp observable in the ripe fruit (_Lign.
63. fig. 9_) is well marked. The largest specimen of Nipadites from
Schaerbeek, is above seven inches long and four wide. The arenaceous
strata containing these fruits, and stems of palms and dicotyledonous
trees, are supposed to have been formed in the sea near the mouth of
a river, as in the case of the clay-beds at Sheppey: the vegetable
remains are associated with bones of fresh-water Turtles, teeth of
Sharks, cases and spines of Echinoderms, and shells of the genera
Ostrea, Pinna, &c.[168]
[167] "On the Belgian Tertiary Formations," Geol. Journal, vol. viii. p.
344.
[168] Geol. Journal, vol. viii. p. 347.
* * * * *
[Sidenote: FOSSIL PANDANUS.]
Fossil Fruit of Pandanus. (_Popocarya._ _Bd._ pl. lxii. p. 503.)--The
_Pandanaceæ_ are monocotyledonous trees, named Screw Pines from the
spiral insertion of their long, rigid, sword-like leaves, along the
stem; they are natives of hot climates, and abound in the groups of
islands in the Pacific; being generally the first important vegetable
tenants of the newly-formed Atols or coral-islands. As in the palms,
the stem is supported near the base by long side-roots, which enable
these trees to maintain an erect position, and flourish on the
newly-elevated coral-reefs, where but little soil has accumulated.
The existence of this tribe of plants during the secondary ages is
known only by a single example of a fossil fruit, which was discovered
by Mr. Page, of Bishport, in the Inferior Oolite, to the east of
Charmouth, Dorsetshire, and is preserved in the museum at Oxford; no
vestiges of the stems or foliage have been observed.
[Illustration: Lign. 65. Fossil Wood with Teredines; _nat._
_London Clay, Regent's Park._
Fig. 1.--A polished transverse section, showing the tubes lined with
spar.
2.--Portions of mineralized Teredines, seen in relief on the wood.
]
This carpolithe, (for a detailed account and figures see _Bd._ p. 504,
pl. lxiii.) is of the size of a large orange; the surface is covered
with a stellated epicarpium, composed of hexagonal tubercles forming
the summits of cells which occupy the entire circumference of the
fruit. Each cell contains a single seed, usually hexagonal, resembling
a small grain of rice, and is supported by a foot-stalk, formed of
dense fibres; a character exhibited only by the seed-vessels of
Pandanus. The fossil fruit differs from that of the recent Screw-pines
in the seeds being neither inclosed in a hard nut, nor collected into
drupes, but dispersed uniformly over the entire mass; this forms the
essential generic distinction between them. Dr. Buckland has named this
unique carpolithe _Podocarya_. (_Bd._ p. 505.)
Wood perforated by Teredinæ. _Lign. 65._--The drifted trunks and masses
of wood found in the London Clay, at Sheppey, Bognor, Bracklesham, &c.,
some of which belong to Palms, others to Conifers, and Dicotyledons,
are commonly more or less perforated by the boring mollusks called
_Teredo_, or _Teredina_; and remains of their testaceous tubes are
often well preserved. The tortuous channels excavated in the wood by
these borers, are lined or filled up with calcareous spar, indurated
clay, or other mineral matter, of various shades of grey, blue, yellow,
&c.; and the polished slabs of this fossil wood are beautifully
diversified by the sections of the sparry tubes, crossed at right
angles by the ligneous structure; as in the specimen _fig. 1, Lign.
65_, from the Canal in the Regent's Park.[169]
[169] Slabs of this kind are generally kept by the lapidaries at Bognor,
Worthing, &c. and sold at 2_s._ or 2_s._ 6_d._ each.
In the fossil, _fig. 2. Lign. 65_, from the Isle of Sheppey, the
tubes of the teredinæ are seen in relief, in consequence of the surface
of the block of wood having decayed and been removed.
Fossil Liliaceæ.--The family of endogens, termed _Liliaceæ_, comprises
many beautiful plants; those with annual stems, as the Lily, Hyacinth,
Tulip, &c. are well known for the variety and splendour of their
blossoms; some of the arborescent forms, as the Tulip-tree, attain a
large size, but the flowers of this division are relatively small.
In tertiary strata, the stems, leaves, fruits, and even the imprints
of flowers, have been discovered, of plants related to _Sagittaria_
(Arrow-head), _Smilax_ (Bind-weed), _Convallaria_ (Lily of the valley),
&c.
The Dracæna (_Dragon-blood tree_), a tall, slender, elegant tree with
amplexicaul leaves (common in our hot-houses), belongs to this family;
and certain stems found with Clathrariæ, and bones of the Iguanodon,
in the Kentish-rag at Maidstone (_ante_, p. 173), so closely resemble
the trunk of this plant, that they have been named by Mr. König,[170]
_Dracæna Benstedi_; the specimens are in the British Museum. Until the
internal structure of these fossils has been examined, the correctness
of this identification is, however, uncertain: the external
resemblance to the stem of the Dracæna consists in the interrupted
annular ridges, denoting amplexicaul leaves: no vestiges of the foliage
have been observed.
[170] Petrifactions, p. 49.
[Sidenote: FRESH-WATER PLANTS. FOSSIL CHARÆ.]
Fossil Fresh-water Plants.--The tertiary fresh-water strata often
contain abundance of the remains of the aquatic vegetables that
inhabited the lakes and rivers in which those deposits were formed. The
remains of several species of the common lacustrine plant, the _Chara_,
are found in immense quantities in the fresh-water limestones and marls
of the Isle of Wight, of the coast of Hampshire, and of the Paris
Basin. The shell-marls, still in progress of formation in the lakes of
Scotland, and the travertine precipitated from thermal springs, in like
manner envelop and preserve the leaves and fruits of recent species.
Fossil Fruits of Chara. (_Gyrogonites._) _Lign. 66._--The Chara is a
well-known inhabitant of almost every stream and rivulet. The stems
are hollow, and composed of tubes filled with a fluid in which green
globules circulate; they form beautiful microscopic objects for
exhibiting the circulation in vegetables. The fruit consists of very
small nuclei, contained in a calcareous pericarp, composed of five
spirally twisted plates, that unite at the summit. These seed-vessels,
when first discovered in a fossil state, were supposed to be the shells
of mollusks, and a genus was formed for their reception with the name
of _Gyrogonites_ (_twisted-stones_); a term still employed, though the
vegetable nature of these bodies is well known. In _Plate III. fig. 5_,
a branch of the common Chara with seeds is represented: and figures
of the seed-vessels, of two fossil species are given in _Lign. 66,
figs. 1, 2_.
Specimens of the fossil fruits and stems of Charæ, may be collected
in abundance in the fresh-water limestone at East Cliff Bay, Isle of
Wight.[171]
[171] See my Geology of the Isle of Wight, _Lign. 5_, p. 109.
[Illustration: Lign. 66. Fossil Fresh-water Plants.
_Eocene, Paris._
Fig. 1.--Seed-vessel of _Chara helicteres_ × 10; side view.
1_a_.--View of the base of the same.
1_b_.--One of the spiral valves separated.
1_c_.--View from above.
2.--Seed-vessel of _Chara medicaginula_ × 10. The upper
figure is a side view: the lower, a view of the base.
3.--_Carpolithes ovulum_, magnified side view.
3_a_.--The same, natural size.
3_b_.--Magnified view of the base of the same.
4.--A piece of fresh-water limestone, with impressions
of two stems of _Nymphea arethusa_ ×.
]
The _Purbeck beds_ at Durlstone Bay, near Swanage, also contain
numerous Gyrogonites associated with fresh-water shells. The bands of
siliceous sinter, which occur in the lowermost deposits, are especially
rich in these remains.[172]
[172] I am indebted to the Rev. Osmond Fisher, of Dorchester, for a fine
suite of these and other interesting fossils from the Purbeck beds of
Ridgway and Osmington, near Weymouth; and to William Shipp, Esq., of
Blandford, and Edward Woodhouse, Esq., of Ansty, for many specimens
from Durlstone Bay, and Ridgway.
_Fossil Nympheæ._ _Lign. 66, fig. 4._--Those magnificent aquatic
plants, the Water-Lilies (_Nympheæ_), that adorn our rivers and lakes
with flowers and foliage which partake more of the characters of
an exotic flora than any other of our indigenous plants, are also
found fossil in the lacustrine marls and limestones of the tertiary
formations of France; but the nature of these remains could only be
recognized by a profound botanist, for they consist of impressions of
the internal structure of the stems, which, however, is so peculiar,
that no reasonable doubt of their origin can be entertained. Two
imprints on a piece of limestone from Lonjumeau, presented to me by the
late M. Alex. Brongniart, are figured in _Lign. 66, fig. 4_; some
minute seed-vessels (_Lign. 66, fig. 3_), found with them, closely
resemble those of _Nympheæ_, and are supposed to belong to the same
plants (_Class. Vég. Foss._ p. 72).
Fossil Flowers.--The tertiary limestones of Monte Bolca (_Wond._ p.
565), so rich in ichthyolites, and other fossil remains of great
interest, contain leaves, and even flowers, of liliaceous plants.
The specimen figured (_Lign. 67, fig. 3_) is in the Museum at
Paris, and described by M. Brongniart under the name of _Antholithes_
(stone-flower) _liliaceus_; it consists of the corolla and calyx:
the anthers and pistils have not been observed in any example. The
discovery of this fossil should excite the young collector to search
diligently for such objects in the tertiary strata of England.
[Sidenote: FOSSIL ANGIOSPERMS.]
Fossil Angiosperms.--The fossil remains of the class which constitutes
the grand features of the existing floras of most countries, the
_Exogenous Angiosperms_, are now to be considered; and though our
survey of fossil botany has partaken but little of a geological
arrangement, yet the reader may have observed, that a large proportion
of the vegetables composing the floras of the ancient secondary
formations, belonged to the Cryptogamous and Gymnospermous classes.
A striking contrast is presented in the geological position of the
mineralized dicotyledonous plants, of existing genera. These abound in
the tertiary strata, and generally in an inverse ratio to the antiquity
of the deposit, while their remains are almost wholly absent in the
older rocks; neither have there been discovered in the Tertiary,
any beds of vascular cryptogamia, at all approaching the immense
accumulations in the Carboniferous formations.
[Illustration: Lign. 67. Fossil Nuts, and Flower.
Fig. 1.--Thalictroides Parisensis; Tertiary strata, Paris.
2.--Thalictroides Websteri. Isle of Wight.
3.--Antholithes liliaceus. Monte Bolca.
4.--Juglans nux-taurinensis: fossil Walnut, Turin.
4_a_.---Portion of the husk of the shell.
4_b_.--The kernel, formed of calcareous spar.
]
The most remarkable exception, is the single instance of a large leaf
of a dicotyledonous plant in the Trias, or New Red sandstone, near
Liverpool, described by Sir Roderick Murchison, which much resembles
the foliage of a thick-ribbed Cabbage.[FQ]
[173] This fossil is named _Dictyophyllum crassinervium_, by Dr. Lindley,
Foss. Flor. pl. cci. and is figured, Sil. Syst. p. 43.
It would be impossible, within the limits necessarily assigned to
these volumes, to offer even a general view of the fossil remains of
this grand class of vegetables; our remarks must be limited to a few
interesting examples and localities.
When stems of dicotyledonous trees only are found, but little certainty
can be obtained as to the family to which they belonged; the foliage of
many well-known genera offer more positive characters; the flowers are
rarely in a state of preservation to afford any valuable data; but the
fruits, or seed-vessels, are frequently well preserved, and these may
enable the botanist to arrive at precise determinations as to generic,
and, perhaps, specific relations.
The tertiary marls of Aix, in Provence, which abound in insects,
crustaceans, and lacustrine shells, contain many kinds of
dicotyledonous leaves, associated with those of palms. (_Wond._ p. 260.)
The Lignite, or Brown-coal deposits, are almost entirely composed of
dicotyledonous trees, belonging to many genera, which are inhabitants
of Europe; namely, the Poplar, Willow, Elm, Chestnut, Walnut, Sycamore,
Maple, Linden, Buckthorn, Vine, &c. (_Bd._ vol. i. pp. 508-514.)
The beds of brown coal, on the banks of the Rhine, are literally
carbonized submerged forests, which in some remote period were drifted
from the interior of the Continent into a vast lake or gulf; for the
trees bear evident marks of transport, and are destitute of roots and
branches. These masses resemble the rafts of forest trees, which are
daily floated down the Mississippi into the Atlantic, where they become
engulfed in the profound depths of the ocean, and probably will be
converted into coal or lignite; and in future ages, may be elevated
above the waters, become dry land, and present to the then existing
communities of mankind an inexhaustible supply of mineral fuel,
composed of species and genera of plants, which possibly may then be
extinct, and replaced by peculiar types of vegetation.
Fossil Flora of Œningen. (_Bd._ pp. 511-514).--The celebrated
lacustrine tertiary formation of Œningen, whose fossil reptiles and
mammalia we shall have to notice hereafter, contains a rich assemblage
of dicotyledonous and gymnospermous ligneous vegetables, with a few
ferns and grasses. Not only branches and leaves of a species of
Vine[174] occur, but even the fruit; fossil grapes being found in these
deposits;[175] there are also many aquatic plants. A descriptive list
of these fossils, by Professor Braun, of Carlsruhe, is given by Dr.
Buckland. The brown-coal of this basin is in thin beds of but little
economical importance, but so rich in the vegetation of the miocene
tertiary period, that a few days spent in collecting those treasures
will amply reward the intelligent tourist who may visit Constance. (See
_Wond._ p. 263.)
[174] See Knorr, Mon. des Catastrophes, pl. xxxviii. tom. i.
[175] Fossil grapes from the lignite of Œningen were exhibited by Dr.
Daubeny at a late meeting of the Geological Society.
[Sidenote: FOSSIL DICOTYLEDONOUS LEAVES.]
The foliage of dicotyledonous trees frequently occurs in the Eocene
marls and limestones, and in some localities in considerable abundance,
and in beautiful preservation. Near Bournemouth, on the Hampshire
coast, the leaves of many species are met with in a bed of sandy
marl, between three and four feet thick: the vegetable substance
is carbonized; some of the leaves are referable to the _Lauraceæ_
and _Amentaceæ_, others to the _Characeæ_;[176] a similar deposit of
tertiary plants has been discovered near Wareham. These beds belong to
the lower group of the Hampshire Basin.[177]
[176] Geol. Proc. vol. iii. p. 592.
[177] As the seed-vessels and other vegetable remains in the Isle
of Sheppey are all of a tropical character, while those found in
the Eocene strata of Alum Bay, Bournemouth, and Newhaven, are of a
temperate climate, as Nerium, Platanus, &c., Prof. E. Forbes infers
that the former were transported from distant lands by currents, and
that the latter belong to the true flora of the country inhabited by
the Palæotheria and other associated mammalia.
[Illustration: Lign. 68. Imprints of Dicotyledonous Leaves in Gypseous
Marl.
_Tertiary. Stradella, near Pavia._
Fig. 1.--Leaf of Poplar (_Populus græca_).
2.--------- Maple (_Acer_).
3.--------- Water-spike (_Potamogeton_).
4.--------- Willow (_Salix_).
5.--------- Chestnut (_Æsculvs_).
]
The red marlstone associated with lignite in the plastic clay beds
at Castle Hill, Newhaven (_Geol. S. E._ p. 54), contains leaves of a
similar kind; a seed-vessel of a coniferous tree has also been found in
it.
Some of the most interesting examples of dicotyledonous leaves
that have come under my notice, are from the Sub-Apennine tertiary
strata, at Stradella, near Pavia. They belong to several genera of
arborescent, or at least ligneous plants, and most of them to species
which still grow in Italy. In some examples the substance of the
leaves is changed into carbon, and the structure well preserved; but,
in general, sharp imprints on the stone are the only traces of the
originals. They are found in a gypseous marl, of a cream colour; and,
from their perfect state, it is inferred that they were enveloped in
the soft matrix immediately after their fall, and preserved by the
rapid crystallization of the gypsum. Two specimens from my cabinet are
figured in _Plate III._ _figs._ 4 and 8; and outlines of a few other
examples, in _Lign. 68_.
Carpolithes (_Fossil Fruits_).--In the description of the fossil
fruits from the Isle of Sheppey, several kinds of dicotyledons were
included. Many species also abound in the lignites of Germany, France,
and Italy; in those near Frankfort, seed-vessels of the Maple, Elm,
Hornbeam, Birch, Willow, and Walnut, &c. In the environs of Turin,
fruits of a species of Walnut (_Juglans_, _Lign. 67_), occur in the
newer tertiary deposits, and are called Turin-nuts; the ligneous
envelope has perished, but the form of its surface, and of the inclosed
kernel, is preserved in calcareous spar. These nuts differ, both in
the pericarp and kernel, from the living species: the lobes are simple
(_Lign. 67, fig. 4^b_), and not subdivided as in the common walnut;
a species has been discovered at Lons-le-Saulnier, in which the lobes
are mamillated.
Two kinds of fruits belonging to plants of the order _Ranunculaceæ_,
and related to _Thalictrum_ (_Meadow-rue_), have been found in the
eocene deposits of France and England; one in the Paris basin,
(_meulière du terrain d'eau douce supérieur_,) by M. Alexandre
Brongniart, and the other in the Isle of Wight, by Mr. Webster. In the
specimen from the last-named locality the pericarp is carbonized, and
its cavity filled with clay. Figures of these seed-vessels are given in
_Lign. 67, figs. 1, 2_.
Carpolithes Smithiæ.--I would notice in this place some very
remarkable fossil fruits that are occasionally met with in the White
Chalk of Sussex and Kent, and appear to belong to dicotyledonous trees.
The first specimen was discovered by me in a chalk-pit near Lewes, and
is described in my "Fossils of the South Downs:" some illustrative
examples collected by Mrs Smith, of Tunbridge Wells, tending to
elucidate the nature of the original more satisfactorily than those
in my collection, are figured and described by me in the Journal of
the Geological Society, 1843, under the above name. These fruits are
of an oval form, about one and a half inch long, and one inch wide,
and are pressed almost flat. They are of a rich burnt-sienna colour,
mottled with white, from the chalk having permeated their substance,
and are studded over with slight eminences, which are the exposed
summits of oblong flattened seeds. Although the internal structure is
not preserved, there can be no doubt that the originals were spurious
compound berries, having, like the Mulberry, the seeds imbedded in a
soft pulpy mass.
[Sidenote: FOSSIL DICOTYLEDONOUS TREES.]
Fossil Dicotyledonous Trees.--The occurrence of trunks and branches of
angiospermous trees in a carbonized state has already been described;
like the monocotyledons and conifers, they also occur silicified.
The most beautiful specimens I have seen are from the Lybian and
Egyptian deserts, and were collected by my friend, the late Colonel
Head. In these the most delicate vascular tissue is permeated by
chalcedony and jasper, and the vessels are filled with silex of a
bright vermilion and blue colour, while the cellular structure is of a
rich yellow. Fragments of these fossil trees are scattered everywhere
among the sands of the desert; the most interesting locality is an
irregular plateau, which reposes on marine limestone, considerably
above the level of the Nile, about seven miles east by south from
Cairo. This district is called the _petrified forest_, from the immense
quantities of silicified trees with which it is covered. It is thus
graphically described by a late traveller:--
"Having passed the tombs of the Caliphs, just beyond the gates of
Cairo, we proceed to the southward nearly at right angles to the road,
across the Desert to Suez: and after travelling some ten miles up a
low barren valley covered with sand, gravel, and sea-shells, fresh
as if the tide had retired but yesterday, we cross a low range of
sand-hills, which has for some distance run parallel to our path. The
scene now presented is beyond conception singular and desolate. Heaps
of fragments of large trees converted into stone everywhere meet the
eye, and when struck by our horses' hoofs rang like cast iron; they
extend for miles in the form of a decayed and prostrate forest; and the
appearance is so natural, that were it in Scotland or Ireland, it would
pass without remark as a drained bog, on which the exhumed trees lay
rotting in the sun. The roots, and rudiments of the branches, are in
many cases nearly perfect, and in some the worm-holes eaten under the
bark are distinctly recognizable."[178]
[178] Bombay Times.
Many of the trunks are scattered over the surface, among rolled and
angular fragments of dark grit, and pebbles of jasper,[179] chert,
and quartz. The large trunks occur in great numbers on dark-coloured
knolls, where they lie, like the broken stems of a prostrate forest,
crossing each other at various angles. Two of the largest measured
respectively forty-eight, and sixty feet in length, and two and
a half, and three feet in diameter, at the base. With but two or
three exceptions, all the specimens examined microscopically, are
dicotyledons. No traces of seed-vessels or leaves have been detected.
[179] The jaspers are known to lapidaries as _Egyptian Pebbles_.
The situation and condition of these petrified forests, indicate great
changes in the relative position of the land and sea in that part of
Egypt; for the trees must have grown on the dry land formed by the
elevated bottom of a former ocean; which must have subsided, and been
covered by beds of sand and pebbles; another elevatory movement must
have raised the entire series of deposits to their present situation,
and the retiring waters have removed the loose portions of the last
formed strata, and dispersed them, with fragments of the silicified
trees, over the surface of the Egyptian and Lybian deserts.[180]
[180] See a Memoir on the Geology of Egypt, Geol. Proc. vol. iii. p.
782; and on the Petrified Forest near Cairo, vol. iv. p. 349, by Lieut.
Newbold, F.R.S.
[Sidenote: DICOTYLEDONOUS OF THE CRETACEOUS EPOCH.]
Dicotyledons of the Cretaceous Epoch.--Among the crowd of interesting
facts relating to the botanical character of the earlier periods of
geology which recent observations have brought to light, one discovery
demands especial notice, and I have reserved it for this place, rather
than introduce it in an earlier section.
In the neighbourhood of Aix-la-Chapelle the lower members of the
Cretaceous formation, viz. the Greensand, Galt, and Chalk-marl, are
well developed, and comprise a series of littoral deposits of the
great Chalk ocean that extended westwardly between France and England,
on both sides of the existing Channel, and eastwardly over North and
Central Germany, Sweden, Poland, and Russia, far into Asia. The series
of strata at Aix-la-Chapelle is several hundred feet in thickness, and
the lowermost beds lie immediately on the Carboniferous rocks of the
country.
Dr. M. H. Debey,[181] to whose scientific labours we are indebted for an
accurate knowledge of these interesting facts, divides these cretaceous
deposits into four groups, the lowermost of which appears to be the
equivalent of our Greensand; it consists of beds of clay and sand, the
middle portion abounding in stems, leaves, and fruit, and the resin of
coniferous trees.
[181] See Geol. Journal, vol. vii. p. 109.
The epidermis of the leaves often occurs in a carbonized state, and is
recognizable by its microscopic structure. Xylophagous mollusks are
found in the petrified and carbonized wood. Fresh-water Desmidiaceæ,
and a few marine remains, are associated with this fossil flora, which
is distinguished by the abundance of Ferns and dicotyledonous leaves,
and the scarcity of Cycads; among them are undoubted _Proteaceæ_.
The specimens collected by M. Debey from the lower cretaceous beds are
the following:
Algæ, 15. Filices, 28. Hydropteridæ, 2. Cycadeæ, 5. Naiadeæ, 5. Palmæ,
1. Coniferæ, 20. Julifloræ, 5. Credneriæ, 3. Leaves of Dicotyledons,
undetermined, 26. Fruits undetermined, 8. Woods.[182]
[182] Geol. Journal, vol. vii. p. 111.
This assemblage of angiosperms, with gymnosperms, and cryptogamia, at
the commencement of the Cretaceous epoch, when the Iguanodon and other
reptilian forms of the Oolite and Wealden still inhabited the land
and water, proves, as Sir Charles Lyell has remarked,[183] that the
meteorological phenomena of that remote period differed in no essential
particular from those which now prevail.
[183] Supplement to the New Edition of Elements of Geology, 1852, p. XV.
* * * * *
RETROSPECT OF FOSSIL BOTANY.
[Sidenote: RETROSPECT OF FOSSIL BOTANY.]
If we pass from the consideration of details of structure, and of
botanical affinities, to a general survey of the mineralized remains of
the vegetable kingdom, we perceive that from the palæozoic deposits,
to those which are contemporaneous with the human race,--from the
coal-measures to the peat-bogs of modern times,--vast accumulations
of vegetable matter, in various states of carbonization, have
been produced from the imbedded relics of the terrestrial floras
that flourished during the respective periods of their formation;
petrifaction, or the transmutation of vegetable tissues into stone,
from the infiltration of siliceous, calcareous, or metallic solutions,
being an accidental process, dependent on the physical conditions under
which the trees and plants were submerged, and entombed in the strata.
Although the entire system of vegetable life which prevailed during
the earlier ages of the world is but partially revealed by the fossil
remains which geological researches have brought under the examination
of the naturalist,--for numerous tribes of plants may have existed
of which no traces have been detected, while of species of delicate
tissues all vestiges may have perished,--yet a review of the facts
hitherto obtained, presents some highly important and unexpected
results, as to the characters of the successive floras which prevailed
during the palæozoic, secondary, and tertiary epochs. And though
deductions of this nature must, in the present state of our knowledge,
be regarded in the light of shifting hypotheses to be modified or
abandoned with the progress of discovery,--yet the predominating types
which characterize the flora of one system of formations, differ so
essentially from those of another, that it may be reasonably inferred
such apparent distinctions are the effect of organic laws, and not
illusions arising from our misinterpretation of the natural records of
former conditions of the vegetable world.
The absence in the most ancient deposits of the entire class of
Angiosperms, or flowering plants, which constitutes the leading
features of the floras with which we are familiar,--the abundance of
unknown types of Cryptogamia, and the extinction or disappearance of
those tribes in the succeeding formations, and the prevalence of new
species and genera belonging to another class;--the predominance in
one flora, both in number and variety, of certain tribes, and their
decadence in the next period; while a family subordinate in the
antecedent epoch, and known but by a small number of species, suddenly
acquires a pre-eminence both in numbers and variety;--are phenomena,
which the facts brought before us in the course of this argument,
present in a striking point of view.
Assuming these data as the basis of a philosophical generalization,
M. Brongniart arranges the known species of fossil plants into three
grand systems, which correspond with the great geological periods,
comprehended in the palæozoic, secondary, and tertiary formations.
The first or most ancient flora is characterized by the predominance of
_Cryptogamic Acrogens_--the _Ferns_ and _Club-mosses_; the second by
the large development of the _Dicotyledonous Gymnosperms_--the _Cycads_
and _Conifers_: the third by the appearance and prevalence of the
_Angiosperms_, both dicotyledonous and monocotyledonous. The following
table presents a concise view of the results of M. Brongniart's
investigation.[184]
[184] For details, and a masterly review of the subject, the original
Memoir must be consulted. See Tableau des Genres de Végétaux Fossiles,
considérés sur le point de vue de leur Classification Botanique et de
leur Distribution Géologique, par M. Adolphe Brongniart. Paris, 1849.
CHARACTER OF THE FLORAS. GEOLOGICAL EPOCHS.
I. Règne des Acrogènes; the Flora } The _Devonian_, _Carboniferous_,
of Vascular Cryptogamia. } and _Permian_, Formations.
II. Règne des Gymnospermes; the } The _Triassic_, _Jurassic_ (or
Flora of Cycadaceæ and Coniferæ. } _Lias_ and _Oolite_), and
} _Wealden_, Formations.
III. Règne des Angiospermes. } The _Cretaceous_, and _Tertiary_
Flora of Dicotyledonous and } (_Eocene_, _Miocene_, and
Monocotyledonous flowering } _Pliocene_), Formations.
plants, or Angiosperms. }
It must be observed that this table is only designed to indicate the
successive _predominance_ of each of the three classes of the vegetable
kingdom, in the respective epochs, and not the entire exclusion of the
others. Thus, in the two first, both Acrogens and Gymnosperms existed;
but in the first period the former greatly exceeded the latter, both
in number and magnitude; while in the next the Gymnosperms acquired the
ascendancy; but in both these epochs, from the Devonian to the Wealden
inclusive, very few if any Angiosperms, or flowering dicotyledons,
existed. With the Cretaceous period the Angiosperms appear in great
numbers, and in the Tertiary epochs acquire the importance they possess
in the existing floras.
The following analysis of the flora of the Carboniferous epoch, by M.
Brongniart, will exemplify these remarks.[185]
[185] See Wonders of Geology, vol. ii. pp. 726-733, for an account of
the Carboniferous floras and deposits.
ANALYSIS OF THE CARBONIFEROUS FLORA
Cryptogamia (_Amphigens_). Algæ 4
Champignons 6
--- 6
(_Acrogens_). Ferns 250
Lycopodiaceæ (Club-mosses) 83
Equisetaceæ 13
--- 346
Dicotyledonous Gymnosperms. Asterophyllites 44
Sigillariæ 60
Nœggerathiæ 12
Cycadeæ? 3
Coniferæ 16
--- 135
_Dicotyledonous Angiosperms_ 0
_Monocotyledons?_ (very doubtful) 15
---
502
---
Thus out of five hundred species, 352 are Cryptogamia; and with the
exception of six, belong to the Acrogens.[186]
[186] Bronn gives the annexed numerical summary of the fossil and recent
species of plants:--
_Plants._--Cellular 188 Fossil. 9,100 Living.
Vascular 1,867 60,303
----- ------
2,055 69,403 (80,000, Lindley.)
----- ------
In conclusion, I must direct attention to a remarkable character of the
palæozoic and secondary floras, namely, the almost entire absence of
the _Gramineæ_ or Grasses, which constitute so large a proportion of
the existing vegetation.
Above six hundred species of plants have been discovered in the British
strata;[187] and yet two species of _Poa_ (a tribe of grasses), from
Coalbrook Dale, are the only known examples of Gramineæ. It has been
suggested that the greater or lesser durability of the foliage of
certain vegetables, may have occasioned their presence or absence in
the carboniferous deposits, and experiments were instituted by Dr.
Lindley with the view of determining this question. But though it was
found that, when the foliage of various families was subjected to
long maceration, the leaves of dicotyledons and grasses disappeared,
while those of ferns and cycads remained, this fact does not meet the
exigencies of the case, for we have no evidence to show that the fossil
leaves were ever placed in similar conditions; on the contrary, there
is reason to conclude that they were imbedded under circumstances that
arrested the usual progress of decomposition, prevented the escape
of the hydrogen and other gaseous elements, and gave rise to the
bituminous fermentation by which they were converted into lignite and
coal; and we have no proof that, had grasses been associated with the
ferns, they would not have undergone a similar change. Moreover, there
are countries in which the ferns now assume the numerical proportion of
the grasses of other latitudes; for example. New Zealand, which also
presents in its fauna a striking analogy to that of the carboniferous
deposits, in the almost entire absence of indigenous mammalia; one
species of Rat being the only known living quadruped.
[187] See Mr. Morris's Catalogue of British Fossils.
On this subject Dr. Dieffenbach remarks, that "although in its flora
New Zealand has some relationship with the two large continents between
which it is situated, America and Australia, and even possesses some
species identical with those of Europe, without the Latter being
referable to an introduction by Europeans, yet the greater number of
species, and even genera, are peculiar to it. New Zealand, with the
adjacent islands, Chatham, Auckland, and Macquarrie, forms a botanical
centre. It is sufficiently distant from both continents to preserve
its botanical peculiarities, and it offers the most striking instance
of an acknowledged fact in all branches of natural history, viz. that
the different regions of the globe are endowed with peculiar forms of
animal and vegetable life. The number of species of plants at present
known is 632, of which 314 are dicotyledonous, and the rest, or 318,
are monocotyledonous and cellular. The monocotyledons are few in
comparison with the cellular plants, for there are but seventy-six
species. The grasses have given way to ferns, for the ferns and
fern-like plants are by far the most abundant in New Zealand, and cover
immense districts. They _replace the Gramineæ_ of other countries, and
give a character to all the open land of the hills and plains. Some
of the arborescent kinds grow to thirty feet and more in height, and
the variety and elegance of their forms, from the minutest species to
the most gigantic, are very remarkable."[188] In the accumulations of
vegetable matter now in the progress of formation in the morasses,
bays, and creeks of New Zealand, the remains of ferns largely
predominate; and I am informed by my son,[189] that in the estuaries
they are associated with numerous shells of brachiopodous mollusca.
[188] Dr. Dieffenbach's New Zealand.
[189] Mr. Walter Mantell, of Wellington, New Zealand.
* * * * *
ON COLLECTING BRITISH FOSSIL VEGETABLES.
[Sidenote: ON COLLECTING FOSSIL VEGETABLES.]
From what has been advanced, the student will perceive that to obtain
an illustrative collection of the fossil plants of Great Britain, many
different localities must be visited.
The fruits and stems of Palms, Conifers, and many dicotyledons, may be
collected in the Isle of Sheppey, and other places where the London
Clay is exposed. (See _Excursion to the Isle of Sheppey_, Part IV.)
Cycadeous stems and coniferous wood may be procured in the Isle of
Portland; from the Wealden Cliffs along the southern shore of the Isle
of Wight; and on the Sussex coast, from Bexhill, by St. Leonard's,
to the east of Hastings. The foliage of several species of Zamiæ and
ferns, occur abundantly in the lower Oolite, along the Yorkshire coast,
near Scarborough, and at Gristhorpe Bay. The Lias of Lyme Regis,
Charmouth, and their vicinity, affords stems and branches of coniferous
trees, and leaves of cycads.
Ferns, Sigillariæ, Calamites, and the usual plants of the carboniferous
flora, may be found in every coal-mine; and the Devonian limestones
of the South of Ireland yield ferns and Lepidodendra. In Forfarshire
the lower Devonian shales abound in the foliage of aquatic, apparently
fluviatile, plants.[190]
[190] See Memoir on the Telerpeton; Geol. Journ. vol. viii. p. 106.
A list of some of the most productive British localities is subjoined.
In addition to the suggestions already given as to the mode of
collecting specimens, it may be necessary to state that the leaves in
the tertiary marls and clays are generally very delicate and friable,
and liable to flake off in the state of a carbonaceous film. This may,
in a great measure, be prevented by carefully covering them with a thin
coating either of mastic varnish, or gum-water, before they are placed
in the cabinet. In extracting these specimens, a broad chisel will
be found the most convenient instrument. In searching for fossils in
coal-mines, the collector should remember that the ironstone nodules
often contain beautiful examples of the leaves of ferns, and fruits of
Lepidodendra. These nodules, when of an oblong shape, should be split
open in a longitudinal direction, by a smart blow of a hammer, and the
inclosed leaf will thus be exposed, as shown in _Lign. 3, figs. 2, 3_,
_ante_, p. 69.
* * * * *
BRITISH LOCALITIES OF FOSSIL VEGETABLES.
[Sidenote: BRITISH LOCALITIES OF FOSSIL VEGETABLES.]
Allenbank, Berwickshire _Carb._ Stems of Conifers, &c.
Alum Bay, Isle of Wight _Tert._ { Fruit, dicotyledonous leaves,
{ lignite; Charge, stems and
{ seed-vessels.
Ashby-de-la-Zouch, } _Carb._ { Coal plants in great abundance.
Leicestershire }
Bignor, Sussex } _Cret._ } Fucoids.
} _Firestone_ }
Binstead Quarries, near } _Tert._ { Charæ, stems and seed-vessels.
Ryde, Isle of Wight }
Blackdown, Devonshire _Gr. Sand._ Silicified wood--coniferous.
Bognor, Sussex _Tert._ { Coniferous and monocotyledonous
{ wood; washed
{ up on the shore.
Bolton, Lancashire _Carb._ Lepidodendra, Sigillariæ, &c.
Bournemouth, Hants _Tert._ { Dicotyledonous leaves.[191]
[191] Fruits and Fern-leaves have been collected here by Mr. Beckles and
stems of a species of _Arundo_, by Mr. Alfred Woodhouse.
Brook-point, Isle of Wight _Wealden_ { Cycads, and coniferous
{ wood.
Burdie House, near Edinburgh _Carb._ Ferns, wood, &c.
Calbourn, Isle of Wight _Tert._ Charæ, stems and fruits.
Camerton, near Bath _Carb._ Usual plants of the coal.
Charmouth, Dorset _Oolite_ { Coniferous wood; Cycads;
{ fruit of Pandanus.
Clifton, near Manchester _Carb._ { Coal plants in great
{ perfection.
Coalbrook Dale, Shropshire _Carb._ { Usual plants of the coal, in
{ abundance. The ironstone
{ nodules are rich in
{ fern-leaves, fruits of
{ lepidodendrons, &c.
Cuckfield, Sussex _Wealden_ { Clathraria, Endogenites,
{ Ferns, and Lignite.
Durlstone Bay, near Swanage _Wealden_ { Charæ; Gyrogonites in
{ abundance.
Folkstone, Kent _Galt_ { Coniferous wood--bituminous,
{ and pyritified.
Glasgow _Carb._ { Coal plants, and large trunks
{ of Coniferæ.
Hastings, Sussex _Wealden_ { Clathrariæ, Cycads,
{ Endogenites, Ferns, Thuites,
{ &c.
Herne Bay, Kent { _London { Fruits of Conifers, and
{ Clay_ { Palms: wood.
Kilkenny, Ireland _Carb._ Calamites, ferns, &c.
Knocktopher, nr. Kilkenny, } _Devonian_ } Ferns, Lepidodendrons, &c.
Ireland } }
Leeds _Carb._ { Beautiful coal-plants from
{ the pits in the vicinity.
Liverpool _New Red_ Fuci.
Lyme Regis, Dorset _Lias_ Cycads; Conifers; wood.
Maidstone, Kent _Greensand_ { Fruits and wood of Abies,
{ Pinus, Dracæna; Fuci.
Malton _Oolite_ Fruits, and Cycads.
Newcastle (Jarrow Colliery) _Carb._ { Coal plants in great
{ variety.[192]
[192] In collecting _Stigmariæ_, the student should particularly attend
to the relation existing between these fossils and their supposed
stems; for it is probable that roots of this type will be found to
belong to other genera, besides Sigillaria, and Lepidodendron (_ante_,
p. 136).
Newhaven (Castle Hill), } _Tert._ { Dicotyledonous leaves and
Sussex { fruit--_rarely_.
Portishead (on the shore) } _Millstone } Sigillariæ, Stigmariæ, &c.
} Grit_ }
Portland, Isle of _Wealden_ { Petrified forest of Conifers,
{ with Cycads.
Pounceford, Sussex _Wealden_ Equiseta, Ferns, Lignite.
Runswick, Yorkshire Coast { _Lower } Cycads, Ferns, &c.
{ Oolite_ }
Saltwick, near Whitby { _Lower } Foliage of Cycads, Ferns, &c.
{ Oolite_ }
Sandown Bay, Isle of Wight _Wealden_ Conifers, Cycads, wood.
Scarborough _Oolite_ Ferns, Cycads, Equiseta, &c.
Selmeston, Sussex { _Greensand_ } Coniferous wood.
Sheppey, Isle of { _London { Fruits innumerable, wood,
{ Clay_ { &c. (_ante_, p. 186.)
Stonesfield, Oxfordshire _Oolite_ Fuci, Cycads, Thuites, &c.
Swindon, Wilts _Oolite_ Coniferous wood, & Cycads.
Tunbridge Wells (vicinity) _Wealden_ Ferns, several species.
Ventnor, Isle of Wight _Firestone_ Clathraria, Conifers.
Wareham, Dorset _Tert._ { Dicotyledonous foliage, and
{ Palm-leaves.
Whitecliff Bay, I. of Wight _Tert._ Palm-leaves, Charæ, &c.
Whitwick, Leicestershire _Carb._ The usual coal-plants.
The above list must, of course, be considered as merely suggestive:
many other localities are mentioned in the previous notices of the
fossil genera.
PART III.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
FOSSIL ZOOLOGY.
"The very ground on which we tread, and the mountains that surround
us, are vast tumuli in which the Organic Remains of a Former World are
enshrined."--Parkinson.
The existing species of animals scientifically determined by
naturalists amount to upwards of one hundred thousand, while those
known in a fossil state scarcely exceed twenty-five thousand; yet the
latter comprise examples of all the classes, and most of the families
and genera, which still inhabit our planet. Although our notice of
these remains must necessarily be very general, we shall endeavour to
describe all that are of peculiar interest, either in a geological
or zoological point of view; or which from their prevalence, or wide
distribution, will frequently be met with by the collector in the
course of his researches.
Our examination will commence with animal organisms of the simplest
structure, and proceed in an ascending order, in accordance with the
usual zoological classifications; but, as in the botanical department,
it will be convenient occasionally to include the consideration of
the fossil remains of more than one family in the same section, when
associated in a particular locality or deposit.
In the preliminary remarks on the nature of Organic Remains (_ante_, p.
43), the various conditions in which the durable structures of animals
are preserved in the mineral kingdom, were fully explained; we may
therefore at once enter upon the investigation of this most important
division of our subject; that to which the term _Palæontology_, is,
indeed, restricted by some authors.
The fossil remains of the animal kingdom will be treated of under the
following heads:--
I. Zoophytes: including--
1. Porifera, or Amorphozoa: the most simple animal
structures; as the _Sponges_.
2. Polypifera, or Polypiaria; _Coral-animals_.
3. Bryozoa, or _Molluscan Zoophytes_; as the _Flustræ_.
II. Echinodermata, or Echinoderms; Comprising--
1. Crinoidea; or Lily-shaped animals.
2. Asteriadæ; _Star-fishes_.
3. Echinidæ; _Sea-urchins_.
III. Mollusca, or Mollusks. Under this head not only
the fossil shells of testaceous mollusca, but also
those of a lower order of animals, the _Rhizopodes_,
or _Foraminifera_, will be treated of.
1. Foraminifera.
2. Bivalves: the Lamellibranchia, and Brachiopoda.
3. Univalves: the Gasteropoda and Pteropoda.
4. Cephalopoda; those with chambered shells, as the _Nautilus_
and _Ammonite_; and the naked tribes, the Sepiadæ,
or _Cuttle-fish_.
IV. Articulata. (Animals protected by a hard jointed
envelope or case.)
1. Cirripedia: as the _Balanus_, or Barnacle.
2. Annelida: red-blooded worms, as the _Serpulidæ_.
3. Insecta, and Arachnida or _Spiders_.
4. Crustacea; including _Crabs_, _Lobsters_, _Trilobites_, &c.
V. Pisces; or Fishes.
VI. Reptilia; or Reptiles.
VII. Aves; or Birds.
VIII. Mammalia.
IX. Man.
CHAPTER VII.
FOSSIL ZOOPHYTES.--PORIFERA OR AMORPHOZOA--POLYPIFERA OR
CORALS--BRYOZOA OR MOLLUSCAN ZOOPHYTES.
Many tribes of the extraordinary beings whose mineralized relics are
the immediate subject of our investigation, have largely contributed
to the solid materials of which the sedimentary strata are composed.
In the most ancient rocks in which vestiges of organic structures have
been detected, those of _Zoophytes_ hold a conspicuous place; and in
the seas of tropical climates, the agency of the Coral-animalcules, or
Polypifera, is producing enormous deposits, and laying the foundations
of new islands and continents, and forming reefs of rocks hundreds of
miles in extent, which, if elevated above the level of the sea, would
rival in magnitude the mountain-chains of modern Europe.
The reader unacquainted with the natural history of these marvellous
creatures will find an account of their nature and economy, and of the
physical effects produced on the earth's surface by their agency, in
the sixth lecture of _Wond._ vol. ii. p. 588.
The term Zoophytes, or animal-plants, comprises two very distinct
classes of living beings, namely, the Porifera, or Sponges, which (if
not vegetables) are wanting in many attributes regarded as essential
characteristics of the members of the animal kingdom; and the
Polypifera, or polype-bearing-animals,--the Corals; which are generally
associated groups or aggregations of individuals, united by a common
organized mass or axis, each polype having an independent existence,
and exhibiting volition and perception, in a greater or lesser degree.
Fossil Porifera.
[Sidenote: FOSSIL PORIFERA.]
The terms _Amorphozoa_ (signifying animals of variable shapes), and
_Porifera_ (structures traversed by pores or channels), are employed
by naturalists to designate the Sponges and analogous organisms,
which appear to occupy the boundary line that separates the animal
from the vegetable kingdom. The true position of the Sponges in the
great system of Creation is still a disputed point; for while many
distinguished naturalists regard them as _Protozoa_, or the lowest type
of animal organization, others of equal eminence affirm that neither in
structure nor functions do they differ from vegetables in any essential
particular; and that if a line be drawn between the two kingdoms the
Porifera must be placed on the vegetable side of the boundary. On
the other hand, Dr. George Johnston, in his delightful work on the
British Zoophytes,[193] expresses his opinion that there is nothing to
discountenance the belief that these bodies hold an intermediate place;
that they are, in fact, the true _Zoophytes_, or animal-plants; in some
forms, as the green _Spongillæ_ of our lakes, the vegetable nature
prevails; while in others, as the horny or keratose sponges filled
with mucilaginous slime, and the fleshy _Tethya_ whose oscula, or
pores, are said to exhibit signs of irritability, the animal character
predominates.
[193] A History of British Sponges, &c. by Dr. George Johnston,
Edinburgh. 1843. One vol. 8vo. with twenty-five plates. A previous
work, "A History of British Zoophytes," with forty-four plates, from
drawings by the accomplished lady of the Author, cannot be too highly
commended.
Without committing ourselves to either opinion, and simply remarking
that the large proportion of silex that enters into the tissues of
a considerable number of the porifera, is more characteristic of
vegetable than of animal structures, we proceed to consider the fossil
sponges and allied forms, as the mineralized remains of the lowest
types of the animal kingdom: if the vegetable nature of the originals
were generally admitted, this section should have followed that which
treats of the Diatomaceæ (_ante_, p. 100).
Sponge consists of a reticulated fibrous mass, covered with numerous
pores of various sizes, which are connected internally by anastomosing
channels, and this tissue is surrounded by a cellular gelatinous
matter, by which the entire structure was secreted, and is, in fact,
the vital part of the zoophyte. The tough framework or skeleton is in
some kinds fibrous, horny, flexible, or rigid, and strengthened by
calcareous or siliceous spicula (_spines_);[194] while in other species
its substance is calcareous, and in some siliceous, constituting a web
of transparent rock crystal, resembling spun glass,[195] The gelatinous
matter lines all the cavities, and forms the margins of the openings;
it presents no signs of irritability, and may be easily pressed out of
the porous mass with the hand, so slight is the connexion between the
skeleton and the investing tissue. Currents of water constantly enter
the small pores, traverse the inosculating canals, and issue from the
larger orifices, which often project above the surface in perforated
papillæ. By the circulation of the water through the porous structure,
the nutrition of the organized mass is effected; and the modifications
observable in the number, size, form, and disposition of the pores,
channels, and orifices, in different species, appear to be subservient
to this especial purpose; the imbibition and expulsion of water being
the only function the sponges perform. In its earliest stage the sponge
gemmule is of a spheroidal shape, and covered with vibratile cilia, and
after expulsion from the canals in which it is formed, moves rapidly
through the water till it becomes attached to some body, and is then
immovably fixed during life; exhibiting no signs of vitality save the
aqueous circulation through the pores and canals.
[194] The Mediterranean and American sponges of commerce are devoid
of spicules, and are deprived of their soft animal matter simply by
washing freely in fresh water.
[195] I particularly allude to a siliceous Sponge from Barbadoes, named,
by Mr. Samuel Stutchbury, formerly of the Bristol Institution, (now of
Australia.) _Dictyochalix pumicea_. This specimen is of a fungiform
shape, and appears to the naked eye as if formed of pumice stone, but
under the microscope is literally a tissue of transparent silex.
There is much confusion in the arrangement and nomenclature of the
fossil species of this class of zoophytes; and this has originated, in
part, from the varied forms assumed by the same species, having been
described under different names; and from the reprehensible practice of
changing, without sufficient reason, the name assigned to a species by
the original discoverer; an evil, unfortunately, not restricted to this
department of natural history.
The recent Sponges are arranged in four groups according to their
structure, viz.--
_Fresh-water Sponges._
Spongilla: siliceous spicula in a translucent jelly-like mass.
_Marine Sponges._
Tethea: having a tough outer skin; siliceous spicula in bundles, and
radiating from the compact nucleus to the periphery.
Halichondria: (from _silex_ and _cartilago_) siliceous spicula in a
cartilaginous mass.
Grantia: calcareous spicula in a gelatinous mass.
[Sidenote: FOSSIL SPONGES.]
M. D'Orbigny seems to believe that with the exception of the
horny _Cliona_, all the fossil sponges had originally calcareous
skeletons,--"qu'ils n'ont jamais été cornés, mais que leur tissu a
toujours été calcaire et pierreuse;"[196] which is certainly not the
case, for abundant examples of fossil keratose sponges occur.
[196] Cours Elémentaire de Paléontologie, torn. ii. p. 208.
I have selected a few genera for the illustration of the subject, and
shall describe them under the names that are most familiar to the
British scientific collector: doubtless sooner or later some competent
naturalist will undertake the elucidation of this department of
palæontology, and construct a classification and nomenclature based
on natural characters; till then the student will find it hopeless to
attempt to learn the ever-varying names of genera and species applied
to fossil Porifera and Polypifera, by different observers.[197]
[197] It has happened most unfortunately, that but recently Mr.
Lonsdale, in the late Mr. Dixon's beautiful work on Chalk and
Tertiary Fossils, and Mr. Milne Edwards in his able Monograph in the
Palæontological Society's Memoirs, have described many of our chalk
Corals under different specific and generic names.
[Sidenote: SPONGITES IN CHALK AND FLINT.]
On the Sponges in Chalk and Flint.--From the durability of the tissue
of the flexible sponges, and the imperishable nature of those which
have a siliceous or calcareous endo-skeleton or framework, their fossil
remains generally occur in a fine state of preservation, and in immense
quantities, in the sediments that were deposited in those parts of the
ancient sea-bottoms, originally inhabited by these zoophytes. Even the
relics of the keratose species, the _Halichondria_, whose structure
consists of siliceous spines imbedded in a cartilaginous mass, are
equally abundant. Sponge-spicula are everywhere met with in the chalk,
flint, and greensand, and many layers in the cretaceous strata are
almost entirely composed of them.
Sponges so commonly form the nuclei of the nodular flints, that some
naturalists have ascribed the formation of the layers and nodules
of silex in the cretaceous rocks to these zoophytes: a supposition
altogether groundless,[198] The various states of mineralization in
which sponges occur in the chalk give rise to many beautiful and highly
instructive fossils, as we shall point out in the course of this
notice. In general the zoophyte is simply invested by the flint, the
pores and tubes being filled with silex, the original tissue appearing
as a brown reticulated calcareous mass. In other examples the sponge
has been permeated by the liquid flint, and subsequently perished; and
in this manner have been formed those hollow nodules which on being
broken are found to contain only a powder, consisting of siliceous
spicules and fragments of silicified sponge. But in numerous instances
the substance of the zoophyte is completely silicified, and the
intimate structure of the original exquisitely preserved; such are many
of the flint-pebbles, and moss-agates, that are mounted as brooches and
other ornaments.
[198] See Wonders of Geology, p. 300. This question is fully considered
in a Memoir entitled Notes of a Microscopical Examination of the Chalk
and Flint of the South-East of England, &c. by the Author, in 1845.
Spongites.[199]--This name I would apply generically to those fossils
which appear to be identical in structure with the ordinary marine
sponges that consist of a fibro-reticulated porous mass, destitute of
regular tubes or canals: the form exceedingly various.
[199] _Achilleum_ of Schweigger.
The fossil sponges of the chalk may be divided into two groups; the
cyathiforms, or cup-shaped, and the ramose, or branched. Flints
inclosing the first kind, generally exhibit externally the form of
the original; those containing the branched species are of irregular
shapes, and except by an experienced observer, the nature of the
enclosed body would not be suspected. On breaking them, the sponge is
often well displayed, as in the specimen figured in _Lign. 69, fig.
2_: the surface of this fossil was covered with a white gritty powder,
made up of minute needle-shaped siliceous spicula.
[Sidenote: SPONGITES IN FLINTS.]
Spongites Ramosus.--A branched sponge, sometimes from twelve to fifteen
inches long, is not uncommon in the flints of the Lewes and Brighton
chalk; the stems and branches are cylindrical, and the terminations
of the latter are rounded and full of large pores. When completely
silicified the structure can only be detected by fracture, but
occasionally the sponge appears to have been saturated with liquid
chalk before it was enveloped in the flint; and as it is coated with
calcareous matter, it may be detached from the nodule entire.[200]
[200] In this manner I obtained the beautiful specimen (now in the
British Museum) figured in my Foss. South Downs, tab, xv. fig. 11. A
branch of this species is represented Pict. Atlas, pl. xxxix. fig. 12.
_Spongites lobatus_ (sp. Fleming) is figured Pict. Atlas, pl. xxxix.
fig. 6.
[Illustration: Lign. 69. Coral, and Spongites.
_Chalk. Sussex._
Fig. 1.--Petalopora pulchella. Upper figure × ×: lower figure, _nat._
_Chalk near Chichester._ (_Mr. Walter Mantell._)
2.--Spongites clavellatus. a branch in the cavity of a flint.
_South Downs._
3.--Siphonia Morrisiana. (G. A. M.) A transverse polished section
of a pebble. _Brighton Beach._
]
A smaller ramose spongite, with numerous short clavate protuberances,
is often met with in the flints of Sussex and Wilts; a branch is
figured in _Lign. 69, fig. 2_.[201]
[201] This spongite is named Polypothecia clavellata, in Miss Benett's
Wiltshire Fossils.
Spongites Townsendi. (_Pict. Atlas_, pl. xli.)--The cyathiform flints,
whose shape depends on the inclosed zoophytes, so much resemble the
cup-shaped sponges of commerce, as to be easily recognized in the
heaps of nodules that are collected in chalk districts for the roads;
they are from one to eight inches in diameter at the upper part, and
many are of a globular or spheroidal shape; the surface has the usual
calcareo-siliceous coating of flint nodules, giving a sensation of
roughness to the touch; the margin of the cup generally exhibits a
narrow band of porous structure, and when broken, sections of the
enclosed body are exposed. These funnel-shaped spongites terminate at
the bottom in a peduncle, whence fibrous root-like processes diverge;
by these appendages the original was fixed to the rock. I have
collected a few specimens in which the roots are attached to a shell,
or pebble, but have never seen any that appeared to occupy the spot
on which they grew. They seem to have been detached from their native
sites by the waves, and transported to a distance, and subsiding into
the tranquil depths of the ocean, became imbedded in the cretaceous
sediments that were accumulating at the bottom.
Spongites (?) labyrinthicus.[202] _Lign. 80, fig. 5._--Another
abundant species of amorphozoa has given rise to sub-hemispherical
flints, rounded below and flat above, with a marginal band of porous
tissue, that expands into flexuous lobes which fill up the area of
the upper surface. When found imbedded in the chalk, the form of this
zoophyte is often preserved entire; the upper part showing the lobated
and flexuous character of the original. Upon breaking these flints,
the organic structure is generally apparent; but in many instances
has perished, and left a cavity which is either partially filled with
stalactitical chalcedony, or lined with quartz crystals. These fossils
vary in size from a walnut to that of an orange; the pedicle has long
processes.
[202] Foss, S. D. tab. xv. _fig._ 7.
A lobed zoophyte, resembling the above in its general form, and
long rootlets, is distinguished by a large central cavity, which is
continued above the body in the form of a cylinder.[203]
[203] Beautiful figures of these and other chalk zoophytes are given
by Mr. Toulmin Smith in his elegant memoir "On the Ventriculidæ."
The specimens above described are named _Bracholites_ by Mr. Smith.
The plan of the present work forbids the discussion of that author's
opinions and inferences.
Spongites (?) flexuosus. _Lign. 80, fig. 10._--Among the
cyathiform flints that abound in the chalk, a very elegant species
is distinguished by a flexuous band that runs round the margin, and
indicates the lobed structure of the original.
In the chalk of Flamborough Head, Yorkshire, many beautiful cyathiform
sponges are preserved, in which the outer surface is thickly covered
with projecting hollow papillæ; these fossils are generally silicified,
the surface and pores being frosted over with minute quartz crystals.
The museum of the York Institution contains a splendid series of these
spongites.[204]
[204] The silicified state of these zoophytes was first detected by Mr.
Charlesworth, who by immersing specimens in dilate hydrochloric acid,
obtained admirable examples of the delicate structure of the original.
[Sidenote: FOSSIL ZOOPHYTES OF FARINGDON.]
Fossil Zoophytes of Faringdon. _Lign. 70, 71, 72._--The richest
locality for fossil sponges in England is in the immediate
neighbourhood of the little town of Faringdon, in Berkshire.[205] The
Greensand beds that overlie the Oolite in that district, consist of
a coarse friable aggregation of sand, comminuted shells, corals,
amorphozoa, and echinoderms, more or less consolidated by a ferruginous
cement. The gravel-pits, as the quarries are locally termed, expose
what evidently were banks of detritus thrown up on the strand of a
sea-margin; among the water-worn and fragmentary relics of oolitic as
well as cretaceous forms, many perfect sponges of various kinds may be
collected in the course of a few hours. Figures of some of the common
species are subjoined.
[205] See Excursions, in vol. ii.
[Illustration: Lign. 70. Fossil Zoophytes.
Fig. 1.--Lunulites radiatus. _Preston Chalk-pits_; view of the convex
side. (_Mr. Walter Mantell._)
1_a_.--Front view; _nat._
1_b_.--Portion of the surface of fig. 1, magnified.
2.--Scyphia intermedia; 1/2 _nat._ _Faringdon._
3.--Lithododendron sociale: the left-hand branch shows a vertical
section at the upper part, displaying the internal structure;
1/2 _nat._ _Mountain Limestone, Yorkshire._
4.--Verticillipora anastomosans. _Faringdon._
5.--Scyphia ramosa; 1/2 _nat._ _Faringdon._
6.--Scyphia foraminosa; 1/2 _nat._ _Faringdon._
7.--Cnemidium astrophorum; 1/3 _nat._ _Faringdon._
]
Scyphia. _Lign. 70, 72._--These spongites are of a tubular, fistulous,
or cylindrical form, and terminate in a rounded pit; they are either
simple or branched, and composed of a firm reticulated tissue; _Lign.
70, fig. 2, 5, 6_, and _Lign. 72, fig. 4_, are examples. The Upper
Greensand at Folkstone and Dover abounds in a flexuous species, named
Scyphia meandrina (_Morris_).
Cnemidium (_Goldfuss_). _Lign. 70, fig. 7._--These sponges consist
of a cluster of turbinated projections, having a central pit above,
and being porous on the external surface, and radiated at the margin.
The mass is dense and fibrous, and is traversed by horizontal canals,
diverging from the centre to the circumference.
[Illustration: Lign. 71. Fossil Sponge; _nat._
(_Chenendopora fungiformis._)
_Greensand. Faringdon._]
Chenendopora.[GX] _Lign. 71._--The species of porifera thus named
are cyathiform, or cup-shaped; externally furrowed, mamillated, or
lobed; internally smooth, and the surface covered with fine pores.
The beautiful species figured (_C. fungiformis_) is abundant in
the gravel-pits, and well known to the quarrymen as "petrified
salt-cellars."
[206] The Pictorial Atlas contains coloured figures of the following:--
Chenendopora fungiformis (_Michelin_), Pict. Atlas, pl. xliv. _fig._ 5:
according to Mr, Morris.
------------ subplana (_Michelin_), ibid, pl. xliv, _fig._ 3.
Scyphia articulata (_Goldfuss_), ibid, pl. xliii. figs. 7, 8, 9.
------- costata (_Goldfuss_), ibid. pl. xliv, fig, 1.
Cnemidium rimulosum (_Goldfuss_), ibid, pl. xliv. _fig._ 3.
[Illustration: Lign. 72. Fossil Zoophytes; _nat._
_Greensand. Faringdon._
Fig. 1.--Tragos peziza.
2.--Probably Chenendopora in a young state.
3.--Verticillipora anastomosans.
4.--Species of Scyphia.
5.--Tragos Faringdoniensis.
]
Tragos. _Lign. 72, fig. 1._--These turbinated sponges are readily
distinguished from the preceding, by the relatively large oscula, or
open papillæ, disposed irregularly on the inner surface; as shown in
the specimen, _fig. 1._ Their tissue is dense and fibrous. The fossil
represented by _fig. 5_, though named Tragos by collectors, appears
to differ in the structure of the inner surface from the type of this
genus: it is a remarkably beautiful species.[207]
[207] It may be convenient to distinguish it as _T. Faringdoniensis_.
The base in all these Greensand sponges is flat and expanded; not
fibrous and root-like, as in the spongites of the chalk previously
described.
Among the shingle at Brighton, Margate, Dover, Isle of Wight, &c.
pebbles containing fossil sponges may frequently be discovered. When
the flint nodule has been broken, and the calcareous particles of
the inclosed zoophytes are washed away by the action of the waves,
a delicate silicified tissue remains.[208] Many of the large solid
pebbles, are portions of silicified sponges, and polished specimens are
beautiful objects under the microscope.
[208] The pebbles represented in Pict. Atlas, pl. xlv. fig. 5, 12, are
specimens of this kind.
[Sidenote: SIPHONIA.]
Siphonia. _Lign. 73._--These fossil porifera are readily distinguished
from those which have engaged our attention by their more symmetrical
structure. The body of the zoophyte is a mass of dense porous tissue,
of a pyriform or bulbous shape, supported by a slender stem fixed
at the base by rootlets. The stem is composed of very fine parallel
longitudinal tubes, which extend to a series of canals that traverse
the mass, and terminate in openings on the surface of a shallow central
cavity, as shown in the section, _fig. 2, Lign. 73_. The characters
of this genus are well exemplified in a common species of the Greensand
(_S. pyriformis_, _Lign. 73_), described by the late Mr. Webster, from
specimens collected in the Isle of Wight, where it occurs in profusion,
near Ventnor, and the Western lines. This zoophyte is pyriform,
(_Lign. 73, fig. 1_,) and has a shallow cylindrical cavity, supported
upon a long slender stem, the base of which is fixed by root-like
processes (_fig. 5_); the transverse fracture shows a section of the
longitudinal tubes. This species has been found in numerous localities
of the Greensand, and also in the Firestone or malm-rock.[209]
[209] Dr. Fitton's figures, Geol. Trans. vol. ii. pl. xv. _a_, are very
beautiful and accurate.
The Portland limestone contains numerous remains of a Siphonia closely
resembling this species; and varied sections of its stems produce the
white markings commonly observable on the slabs of pavements.
[Illustration: Lign. 73. Siphoniæ, from the Greensand; _nat._
_Wilts, and Isle of Wight._
Fig. 1.--Siphonia pyriformis; the body or upper part.
2.--Vertical section of the same, showing the internal structure,
and the central cavity.
3.--Specimen of S. pyriformis in a young state.
4.--Siphonia (_Polypothecia_, of Miss Benett,) lobata; Firestone or
Upper Greensand, Warminster.
5.--The lower part of the stem, and radicles, of S. pyriformis.
]
A group of Sponges from the Upper Greensand, near Warminster, figured
and described by the late Miss Etheldred Benett,[210] under the name of
Polypothecia, comprises several forms that are allied in structure to
the Siphoniæ. These fossils present considerable diversity of shape;
one of the lobed forms is delineated in _Lign. 73, fig. 4_: and a
branched species in _Lign. 74_. Upon breaking the stem of one of these
zoophytes transversely, sections of parallel longitudinal tubes like
those in the Siphoniæ are exhibited.
[210] An elegant Memoir on the Wiltshire Fossils, by this accomplished
lady, is published in Sir R. C. Hoare's "Wiltshire."
[Illustration: Lign. 74.
Polypothecia dichotoma.
_Upper Greensand, Warminster, Wilts._]
The Kentish rag contains irregular ramose spongeous bodies, which
belong to this group of porifera; and Mr. Bensted has discovered
in his quarry, near Maidstone, numerous remains of a polymorphous
lobed zoophyte, having a porous structure beset with spicula. In the
Firestone of Southbourne, Steyning, and Bignor, in Sussex, I have
observed large pyriform and subcylindrical Siphoniæ.
The organization of all these zoophytes was evidently adapted for the
imbibition and circulation of sea-water, in a more perfect and definite
manner than in the irregular simple sponges.
Flint-pebbles inclosing remains of Siphoniæ abound on the Sussex
coast, especially in the shingle near Brighton, having been washed out
of the chalk cliffs. There were several chalk-pits in Edward-street,
(now, I believe, filled up and the area built upon,) in which every
flint enveloped a sponge or siphonia; many specimens were mineralized
by pyrites and beautifully exhibited the internal structure of the
originals.
Siphonia Morrisiana. _Lign. 69, fig. 3._--A polished slice of a
pebble from Brighton, whose markings are derived from the transverse
section of an undescribed zoophyte is figured, _ante_, p. 224: though
scarcely more than half the diameter of the original is preserved,
yet its structure is well shown; the centre is occupied by numerous
parallel openings, the sections of longitudinal tubes, and is
surrounded by a broad zone of spongeous tissue.
I have seen many examples of this beautiful fossil, set for brooches in
the jewellers' shops in the Isle of Wight, and at Brighton.[211]
[211] The specific name is in honour of John Morris, Esq. F.G.S. the
author of the "Catalogue of British Fossils," whose important services
to Palæontology and Geology it is gratifying thus to acknowledge.
There are coloured figures of Siphonite in Pictorial Atlas, pl. xxxix.
_fig._ 9; pl. xlii. _fig._ 3, 4, 5, 7, 12, and 13; pl. xliii. _fig._ 6.
Siphoniæ (chiefly _S. pyriformis_) are abundant in the Upper Greensand,
near Farnham in Surrey, but their tissues are saturated with phosphate
of lime, instead of silica as is ordinarily the case; the entire sponge
usually contains between 50 and 60 per cent, of phosphate: hence these
fossils have, of late, been in great request for manure.[212]
[212] Mr. Payne, of Farnham, a distinguished agriculturist, has largely
made use of them, both in the natural state and treated with sulphuric
acid. The Firestone strata on St. Catherine's Hill, Isle of Wight,
have been dug for a like purpose. See an "Account of the Phosphate
Diggings," in my Isle of Wight, Second Edition, p. 448.
[Sidenote: CHOANITES KÖNIGI.]
Choanites Königi, _Lign. 75._--The zoophyte which has given rise to
the fossils I have distinguished by the name of Choanites,[213] is of
a spheroidal or sub-ovate form, and appears to have been composed of
a softer tissue than the ordinary sponges. It has a central cavity,
and was fixed at the base by long rootlets: its mass is traversed by
numerous tubes or channels, which open on the inner surface of the
cavity; it differs from Siphonia in not having a stem composed of
bundles of tubes, and probably also in its constituent substance.
Among the Sussex and Wiltshire chalk-flints specimens of this zoophyte
are very common; they are easily recognized by the peculiar markings
produced by the silicified tubes that radiate from the centre, as seen
in _Lign. 75, fig. 4_. The semi-diaphanous pebbles on the Sussex
coast, more frequently contain Choanites than any other zoophytes. From
the beautiful and varied markings observable in the polished sections,
they are in great request for brooches, and are termed _petrified
sea-animal flowers_[214] by the lapidaries; among the shingle on the
sea-shore at Bognor, Worthing, and other places, very fine examples may
be collected.
[213] Foss. S. D. p. 178.
[214] From the supposition that the original was an _Actinia_, or
_Sea-Anemone_. A coloured vertical section of a pebble of this kind
is figured in my "Thoughts on a Pebble," Eighth Edition, pl. ii. See
coloured figures of Choanites in Pict. Atlas, pl. xlii. _fig._ 1, 9,
and 10; pl. xliv. _fig._ 8; and pl. xlv. _fig._ 10.
[Illustration: Lign. 75. Choanites Königi. (G. A. M.)
_Chalk, Lewes._
Fig. 1.--Transverse section of a siliceous specimen.
2.--Upper portion of a _Choanite_, in chalk, showing the opening
of the central cavity at _a_.
3.--Vertical section of a Choanite, in flint, exposing a section
of the mass, and canals passing obliquely from the
central cavity, through the substance.
4.--Choanite in flint; the usual appearance of these fossils.
5.--Various kinds of Spicula of fossil sponges; _magnified_.
]
_Lign. 75, fig. 4_, represents the usual appearance of a flint
deriving its form from a Choanite; _fig. 2_, is the upper part of a
Choanite preserved in chalk, and richly coloured by iron; the opening
at the summit, _a_, is the orifice of the central cylindrical cavity,
which is in this instance filled up by chalk, but in flint specimens,
with silex of a different colour to that of the surrounding mass.
If _fig. 2_, were placed on the top of _fig. 4_, the general shape
of the original zoophyte would be represented. The opening at the
base of _fig. 4_, marks the spot whence the processes of attachment
proceeded. The vertical section of a flint, similar to _fig. 4_, is
shown at _fig. 3_; and in this example are seen the central cavity,
and a section of the substance of the zoophyte, which is traversed
by numerous tubes, that ramify through the mass of which the body
was composed, and terminate in openings on the inner wall of the
central cavity, or sac. A transverse section of a similar flint is
delineated in _fig. 1_; the central white spot indicates the sac filled
with flint, and the tubes are seen radiating from it through the
mass; under a powerful lens the interstitial structure appears to be
granular rather than porous. The perfect transparency of the body when
silicified, and the rich tints it has acquired from metallic solutions,
and the compressed state in which it is often found, seem to indicate
that the original mass was a soft gelatinous substance, like that
of the _Actinia_, strengthened by spicula; for numerous tri-radiate
spines, like those on the left-hand of _fig. 5, Lign. 75_, occur
occasionally in chalk specimens.
In many Choanites, which differ in no other respect from the present
species, vertical sections show on each side the central cavity,
large oval spots, that are sections of a canal which traverses the
entire mass, proceeding from the base to the summit, in a spiral coil
around the central cavity. This structure was first detected by Mr.
Cunnington. Mr. Woodward thinks this spiral tube is common to all the
Choanites, and constitutes a generic character; but so many examples
have passed under my examination in which no traces of such a canal are
perceptible, that it may be a specific difference.
Among the chalk amorphozoa whose true affinities are doubtful, is a
small turbinated zoophyte, which I would place provisionally under this
genus; it has a shallow central cavity, with a broad smooth margin, a
reticulated external surface, and radicle processes proceeding from the
base; see _Lign. 80, fig. 1_.
[Sidenote: PARAMOUDRA.]
Paramoudra. _Lign. 76._--This vernacular Irish term was introduced by
Dr. Buckland, in his account of some gigantic flints, thus popularly
named, that occur in the chalk near Belfast, and also at Whitlingham,
near Norwich. These fossils are of an irregular, oblong, spherical,
or pyriform shape, having a cavity above, which, in some specimens,
extends to the bottom; indications of a pedicle are seen at the base;
in short, they closely resemble, upon a large scale, the funnel-shaped
spongites, so frequent in the flints of the South Downs. Their
appearance _in situ_, is represented _Lign. 76_, from Dr. Buckland's
illustrations: _b_, is a single specimen, partly imbedded in the chalk,
and _c_, _d_, two of the fossils in contact, the pedicle of the upper
one lying in the cavity of the lower.
These bodies are from one to two or more feet in length, and from six
inches to a foot in diameter. The appearance, both of the outer and
inner surface, is that of the usual white calcareo-siliceous crust of
spongitic chalk-flints. Upon breaking them, no decided structure is
perceptible; but here and there, patches of red and blue chalcedony
occur, as in the Ventriculites and spongites in chalk-flints; the
originals were probably large goblet-shaped zoophytes, allied to the
sponges, but of so perishable a nature as to leave but few traces of
their organization, save their general form. Specimens may however yet
be found with the structure preserved, for many years elapsed after the
first discovery of flint ventriculites, before I obtained examples that
threw light on their origin and formation.
[Illustration: Lign. 76. "Paramoudra;" seen in a vertical section of a
Chalk-pit, near Moira.
(_The Very Rev. Dr. Buckland._ Geol. Trans, vol. iv.)
_a, a, a._ Layers of flint nodules, alternating with chalk strata,
_b._ A Paramoudra, imbedded in the chalk,
_c, d._ Two of these bodies in contact.
]
In the Devonian slates of Polperro some curious fossils, supposed
to be remains of fishes, have been ascertained by Prof McCoy to be
Amorphozoa, and are described by that eminent palæontologist under the
name of _Steganodictyum_.[215]
[215] "Synopsis of the Classification of the British Palæozoic Fossils,"
by Prof. Sedgwick and Fred. McCoy. 4to. Fas. 2, p. vii. pl. 2 A. 1852.
Clionites (_Morris_) _Lign. 130._--A recent parasitical sponge (first
described by Dr. Grant under the name of _Cliona_), consisting of a
fleshy substance, full of siliceous tubular pin-shaped spicula, gives
rise to those perforations with which oysters and other shells are
often completely riddled,[216] Certain bivalve shells in the cretaceous
seas appear to have been peculiarly obnoxious to the depredations of
similar zoophytes, and in consequence of the cavities left by the decay
of the sponge having subsequently been filled up by flint, a curious
series of fossil bodies has resulted, which we shall more particularly
notice hereafter. These fossils Mr. Morris has distinguished by the
name _Clionites_, to indicate their origin; they are not, however, the
silicified sponge, but inorganic casts, moulded in the excavations.
The common species is _C. Conybearei_: "cells irregular, somewhat
polygonal, with one or more papillæ; surface finely tuberculated;
connecting threads numerous."[217]
[216] For an account of the characters of the recent Cliona, see a
monograph by Mr. Hancock, Annals of Nat. Hist. May 1851.
[217] Ann. Nat. Hist. August 1851, pl. iv, fig. 8.
Spicula, or spines of Porifera. _Lign. 75._--Siliceous spicules, as we
have had occasion to mention, occur in immense quantities in some of
those deposits which abound in the remains of spongites. These spines
are tubular, and of various shapes; some are acicular, or needle-like;
others of a stellate form; many are tri-radiate or multi-radiate; and
some have the shape of a trident; a few of these fossils are figured
in _Lign. 75_. As the _Actinia_, _Gorgonia_, and _Alcyonia_, possess
spicula, some of the fossil spines may have been derived from those
zoophytes. The larger spicules may be discovered with a lens of
moderate power, or even by the unassisted eye; but all will amply repay
a microscopical examination, and the minutest can only thus be detected.
[Sidenote: SPINIFERITES IN FLINTS.]
[Illustration: Lign. 77. A group of Spiniferites in Flint.
(Seen by transmitted light.)
Fig. 1.--A thin-translucent chip of flint; _nat._
2.--The same magnified, and viewed by transmitted light; showing
a group of five Spiniferites.
3.--The same more highly magnified.
4.--Spin. ramosus; one of the animalculites seen in fig.
3, very highly magnified.
5.--Spin. Reginaldi; one of the same group; × 300
diameters.
6.--A variety of S. ramosus; another of the same cluster
of Spiniferites.
]
Spiniferites (_Xanthidium_, Ehrenb.). _Lign. 77._--I propose to
describe in this place those elegant and very minute bodies, that occur
in great numbers in the chalk and flint, and which, on the authority
of M. Ehrenberg, were regarded as identical with the siliceous
frustules of the genus of fresh-water Desmidiæ, named _Xanthidium_[218]
(_ante_, p. 91.) Later and more correct observations have proved that
the fossils under consideration entirely differ from their supposed
homologues; their original substance not being siliceous, but flexible
and membranous; and that instead of being spores of algæ, they are
probably the gemmules either of porifera, or of polypifera.
[218] Several recent species of Xanthidium are figured in _Plate IV._ of
this volume.
To avoid the perpetuation of the error by the retention of the
botanical name of a recent genus of plants, for fossils whose vegetable
origin is very problematical, and which are entirely distinct from
their supposed analogues, I would substitute that of Spiniferites,[219]
a term simply expressive of the general aspect of these bodies; that of
a globe or sphere beset with spines. The appearance of these fossils
will be understood by the examination of a group discovered by Mr.
Reginald Neville Mantell, in a fragment chipped off from a flint
pebble; and I will describe the mode by which these minute objects
were detected, as it offers a good practical lesson for the young
investigator.
[219] From _spina_, a spine, and _fero_, to bear.
The chip of flint is represented, of the natural size, in _Lign. 77,
fig. 1_; it was immersed in oil of turpentine for a short time, and
then placed on a piece of glass, and examined with a moderate power, by
transmitted light, the turpentine having rendered the translucent flint
almost as transparent as glass; this appearance is shown in _fig. 2_;
the organisms here represented are from 1/300 to 1/500 of an inch in
diameter. The half-inch object-glass was next employed, and _fig. 3_
gives the result. The quarter-inch object-glass, and a corresponding
eye-piece, were then substituted, and by the adaptation of a camera
lucida, _figs._ 4, 5, and 6, were delineated. As _fig. 5_ proved to be
a new species, it was named after its discoverer.
The specimens in flint, when rendered transparent and viewed by
transmitted light under a high power, as shown in _Lign. 78_, and
79, appear as hollow globular bodies, beset with spinous processes,
which in most species are fimbriated at the extremities. There is
considerable variety in the form and length of the spines. In _S.
Reginaldi_, these appendages are numerous, regular, short, and
relatively thick: in an elegant species discovered by the Rev. J. B.
Reade (_Lign. 79_) they are long and palmated: in other kinds they are
of intermediate size and proportions.[220]
[220] Excellent figures of several species are given in a Memoir by H.
H. White, Esq. of Clapham, in the Trans. Microscopical Society, vol. i.
p. 77.
[Illustration: Lign. 78.
Spiniferites Reginaldi.
(_Magnified 500 diameters_.)]
[Illustration: Lign. 79.
Spiniferites palmatus; in flint.
(× 500 _diameters_.)]
The apparently torn and collapsed state of the body and arms of some
examples first led me to doubt the siliceous nature of the original
substance; and on my discovery of the soft parts of foraminifera in
flint and chalk, Mr. Deane undertook to search for the so-called
Xanthidia in chalk, that these bodies might be subjected to chemical
analysis,[221] Mr. Deane succeeded in detecting all the usual species in
the Dover chalk, by digesting some chalk in dilute hydrochloric acid,
and mounting the residue in Canada balsam. In this state the shape of
the body is that of a depressed sphere; many of the specimens appear to
have a circular opening, and the arms or spines to be closed at the
extremities. Upon pressure under water between two pieces of glass,
they were torn asunder as a horny or cartilaginous substance would
be, and the spines in contact with the glass were bent. Some after
maceration in water several weeks became flaccid; a proof that they are
not siliceous.[222]
[221] A torn and apparently shrunken specimen from chalk, is represented
in my paper on Foraminifera; _Philos. Trans._ 1846, p. 465.
[222] Memoir on Fossil Xanthidia, by Henry Deane, Esq. Microscopical
Journal, 1846.
The real nature of these fossils must be regarded as still
undetermined: their prevalence in the chalk-flints whose forms are
derived from zoophytes, seems to countenance the supposition that the
Spiniferites are the gemmules or early state of animals of this family;
but I have never detected any organic connexion between them and the
porifera with which they are associated; it is possible they may be the
germs of the remarkable zoophytes we have next to examine.
* * * * *
[Sidenote: VENTRICULITES.]
Ventriculites.[223] _Lign. 80, 81, 82._--At every step of our review
of the fossil zoophytes, I find myself embarrassed by the conflicting
opinions entertained by naturalists, respecting some of the most
abundant of the extinct forms; arising from the imperfect state of
our knowledge as to the structure of the originals, which compels
a comparison with recent types, from which, perhaps, the fossils
differed essentially in their organization. This remark especially
applies to the zoophytes which have given rise to the fungiform flints
so well known to the inhabitants of the chalk districts of Sussex,
as "_petrified mushrooms_," from their close resemblance in form to
fungi: a specimen with this name inscribed on it in the cabinet of a
friend first drew my attention to these curious fossils. In _Lign.
80, figs. 2, 3, 4, 6, 7, 8, 9_, several flints of this kind are
represented; _figs._ 3, 6, 8, are fungiform; _fig._ 7, is the upper
part of a specimen, the stem having been broken off; _figs._ 2 and
4, are examples of the lower part of the zoophyte; in all, there are
openings at the base, and a groove on the margin or edge of the upper
part in which the structure of the inclosed fossil is visible; upon
breaking these flints, sections of a funnel-shaped body are exposed.
[223] Ventriculite; from _ventriculus_, a ventricle or sac.
[Illustration: Lign. 80. Flints, deriving their forms from Zoophytes.
_From the South Downs, near Lewes_; 1/6 _nat._
Fig. 1.--Choanites (?) Turbinatus.
2, 3, 4, 6, 7, 8, 9.--Flints, whose forms are derived from
Ventriculites, provincially called "_petrified mushrooms_."
5.--Spongites labyrinthicus.
10.--Spongites flexuosus.
]
The origin of these fossils will be understood by reference to the
four specimens delineated in _Lign. 81_. In _fig._ 3, a fungiform
flint, resembling _fig._ 6, of _Lign. 80_, is seen in the lower part
of a cup-shaped zoophyte; while above, and surrounding the flint, the
impression remains of the reticulated outer surface, deeply coloured
by a ferruginous tinge. In _fig._ 4, _Lign. 81_, a small turbinated
flint, resembling _fig._ 4, of _Lign. 80_, occupies the base, and three
rootlets are seen emerging from it at a. In _Lign. 82, fig. 1_, in
which the chalk has been removed so as to expose the outer surface of
the Ventriculite, a flint occupies the centre at c; above which, the
radiating reticulated structure is spread out on the chalk, _a_; the
base, with its roots, is shown at _b_.
[Illustration: Lign. 81. Ventriculites radiatus; 1/6 _nat._
_Chalk; near Lewes._
Fig. 1.--A perfect specimen in chalk, inverted, showing the external
reticulated surface; the apex of the base projects in the
centre.
2.--Specimen expanded, displaying the inner surface, studded over
with the openings of the cells or tubes.
3.--A Ventriculite in chalk; the lower part inclosed in flint.
4.--Portion of a Ventriculite; the stem towards the base is
enveloped in flint, and three radicle processes spread from it
into the surrounding chalk at _a_.
]
These specimens demonstrate that all the flints referred to,
have been moulded in the cavities of cyathiform zoophytes;
and that their diversity of figure has arisen from the amount
of silex that happened to permeate the organism; if but a
small proportion of silica in solution was present, then flints,
like _fig._ 4, were produced; if the quantity were sufficient
to fill up a considerable part of the tissues of the original,
fungiform flints, as _Lign. 80, fig. 3_, and _Lign. 81, fig. 3_, were
the result. The disciform flints originated from the expanded
examples, _Lign._ 81, _figs._ 1 and 2: and when the silex
was insufficient to silicify the entire zoophyte, an annular
flint, resembling a quoit, was formed.
[Illustration: Lign. 82. Portions of Ventriculites; 1/4 _nat._
_Chalk, near Lewes._
Fig. 1.--A specimen, in which the middle is inclosed in a flint _c_;
the external structure of the Ventriculite is seen at _a_,
expanded on the chalk; and the pedicle with its roots is
exposed at _b_. The figures are one-fourth the size of the
originals.
2, 3, 5.--Chalk specimens, showing the external structure of stems
of Ventriculites.
4.--A siliceous cast of the cavity of a Ventriculite covered with
papillæ, moulded in the orifices of the cells.
]
The form of the original was evidently that of a hollow inverted cone,
terminating in a point at the base, which was attached by fibrous
rootlets to other bodies. The outer integument was reticulated, that
is, disposed in meshes, like net-work; and the inner surface studded
with regular openings, apparently the orifices of tubular cells. The
substance of the mass appears to have been sufficiently flexible to
expand and contract without laceration. This opinion is based on the
fact, that in many specimens the zoophyte is a nearly flat circular
disc (_Lign. 81, figs. 1, 2_); and in others a subcylindrical pouch. In
the former state the outer reticulated structure is elongated, while
in the latter, it is corrugated; hence I am led to conclude that the
original possessed a common irritability, and was able to contract and
expand like many of the flexible polypiaria. The openings on the inner
surface are cylindrical, and very regular; the flints often present
sharp casts of them, which appear like rows of minute pillars. When the
flint filling up the cavity of a Ventriculite can be extracted, it is a
solid cone, studded with papillæ, the casts of the cells, as in _Lign.
82, fig. 4_.
In the flints, the substance of the Ventriculites is generally as
translucent as that of the Choanites, and defined by its rich purple,
sienna, or grey colour;[224] but towards the base and margin it is
more or less calcareous; and in many examples the whole, or a large
portion of the zoophyte, is in this state. But this fact does not
invalidate the inference that the original was flexible; for in these
instances the tissues may have been immersed in fluid chalk before
their envelopment in flint,[225] The chalk specimens are commonly as
friable and earthy as the surrounding stone, from which they are
distinguishable by their ochreous colour.
[224] Pict. Atlas, pl. xlv. _fig._ 9, represents a beautiful transverse
section of the lower part of a Ventriculite in flint, richly
coloured. Pl. xliii. _fig._ 16, is a pebble containing the base of
a Ventriculite; the orifices on the top have been produced by the
transit of the radicle processes; for the fossil is drawn in an
inverted position, a common error before the origin of these flints was
ascertained.
[225] A piece of sponge dipped in liquid plaster of Paris, and
afterwards inclosed in a transparent substance, as glass, would present
such an appearance.
The stain always observable in the tissues of the chalk Ventriculites
and other zoophytes, while the surrounding white limestone is
uncoloured, may be explained by the chemical changes to which the
decomposition of animal matter under such circumstances would give
rise. If sulphuretted hydrogen were evolved from the putrifying
zoophytes imbedded in calcareous mud containing iron in solution,
the sulphur would enter into combination with the iron, the hydrogen
escape, and a sulphate or sulphuret of iron be deposited, atom by atom,
and thus impart colour and permanence of form to the original.
When the inclosed organisms in the flint nodules have perished,
chalcedony, quartz crystals, or crystallized pyrites, sometimes of
great beauty, are found occupying the cavities; in short, numerous
modifications of the petrifactive process are beautifully exhibited in
these common, but highly interesting, cretaceous fossils.
The species to which the previous remarks more immediately refer, is
named _Ventriculites radiatus_; from the radiated appearance of the
external integument; some of the expanded specimens are more than one
foot in diameter.[226]
[226] The reader interested in the history of these objects should
consult Foss. South Downs, p. 167, plates x, xi, xii. xiii. xiv. A
memoir by the Author on these fossils, under the name of _Alcyonium
chonoides_, with four beautiful plates, was published in the Linnæan
Transactions, vol. xi. 1821. The _Ventriculites_ are the only organic
remains figured in Conybeare and Phillips's Geology of England and
Wales, p. 76.
[Illustration: Lign. 83. Ventriculites alcyonoides. _in Flint. Lewes._
_Ocellaria inclusa. König._
Fig. 1.--Portion of the surface of fig. 2, magnified.
2.--The fossil body extracted from the flint, fig. 4.
2_a_.--Transverse section of the same, showing a central
spot of flint, surrounded by tubular cells.
2_b_.--Two of the cells of fig. 2_a_, highly magnified.
4.--The hollow flint, from which fig. 2 was extracted; the papillæ
on the surface, are casts of the apertures of cells.
]
Ventriculites alcyonoides. _Lign. 83._--Under the name of "_Ocellaria
inclusa_," the late Mr. König[227] figured and described an elegant
fossil zoophyte not uncommon in the chalk and flints of Sussex. This
fossil is inversely conical, and somewhat resembles the cast of the
cavity of _Ventriculites radiatus_, but a little attention will
enable the collector to distinguish it. The flint that is moulded
in _V. radiatus_, is surrounded by the substance of the zoophyte,
and if found detached, with the investing material removed, shows no
structure whatever, but simply a surface covered with minute papillæ.
The present zoophyte is generally included in a nodule, and by a slight
blow may be readily separated from the surrounding flint; it then has
the appearance of a white calcareous cone, beset with regular cells,
disposed in quincunx order (_Lign. 83, fig. 2_); leaving a conical
cavity in the flint, which is covered with corresponding eminences
(_Lign. 83, fig. 4_). Upon breaking the cone itself, it is found to
consist of a dense reticulated structure, from one-eighth to a quarter
of an inch in thickness (_Lign. 83, fig. 2a_), investing a solid
nucleus of flint, the surface of the latter being covered with minute
points, which are less regular than those on the cavity of the outer
case. The specific name, _inclusa_, was suggested by this character;
which, however, is only accidental, for the specimens imbedded in
chalk, are simply surrounded by the stone. It is the calcareous nature
of the fossil, which renders it so easily separable from the investing
flint, while its cells afford numerous points of attachment, and these
remain as casts in relief on the interior of the hollow case: I have
not observed the same regularity of structure on the inner as on the
outer surface.
[227] Icones Foss. Sect. _fig._ 98.
The reticulated integument of this zoophyte resembles in structure
that of _V. radiatus_. With regard to the latter, I should state that
Mr. Toulmin Smith[228] discovered that the inosculating fibres of the
intimate tissue formed an octahedral plexus at each knot or point
of union; and this structure Mr. Smith regards as peculiar to the
Ventriculites, and states that he detected it in all the fossils he has
arranged under the name _Ventriculidæ_. No spicula have been detected
in the integuments.
[228] "On the Ventriculidæ;" a series of papers published in the Annals
of Natural History, with many figures of cretaceous zoophytes. By
Toulmin Smith, Esq.
Until more ample and satisfactory evidence is collected as to the
nature of these fossils, the interests of science will be best promoted
by allowing the question to remain sub judice, and restricting the term
Ventriculites to those zoophytes which possess the general characters
of the type to which the name was originally assigned; namely, a
vasiform or subcylindrical framework, terminating at the base in a
point, and fixed by radicle processes; the substance consisting of
a plexiform fibrous tissue; externally constituting a reticulated
integument, the meshes disposed in a radiating manner from the base
to the periphery; the inner surface studded with open cells regularly
arranged.
In the former edition of this work the Ventriculites were placed with
the Polypifera from the structure of the openings or cells, for these
are so symmetrical, and disposed with so much regularity, as to present
a closer analogy to the polype-cells of a coral, than to the large
pores of a sponge. The doubts expressed by many eminent observers as to
the correctness of this view, have induced me to insert this notice in
the present section; leaving the true affinities of these organisms to
be determined by future observers. Possibly we have in these fossils
the relics of a tribe of zoophytes of an extinct type, that formed a
connecting link between the _porifera_ and the _polypifera_; however
this may be, I will venture to affirm that no one who had seen the
infinitely varied examples of these fossils that I have, would for a
moment confound them, as some naturalists have done, with the Scyphiæ,
and other simple amorphozoa.
[Illustration: Lign. 84.
A Coral-polype in flint.
× 500 _diameters_.
(_Seen by transmitted light._)]
Polype in Flint. _Lign. 84._--I will here notice an exceedingly minute
and interesting object, discovered by the Rev. J. B. Reade, in a flint
containing vestiges of a Ventriculite, and which may possibly belong
to this tribe of zoophytes. It must however be remarked, that there
was nothing to show the collocation was not accidental. The drawing
with which Mr. Reade favoured me, is engraved _Lign. 84_. This object
is unmistakeably a polype-cell, with some of the integument of the
animal protruding, in the form of a shrivelled tube. The possibility
of soft animal tissues being preserved in flint, will not now admit
of question, as we shall show when treating of the Foraminifera. The
record of this fact may load to the discovery of other fossils of a
like nature.
Fossil Polypifera.
[Sidenote: POLYPIFERA.]
As we proceed in our investigations, the impossibility of rigidly
adhering to a zoological classification based on the structure of
organs, of which but few, if any, traces exist in the mineral kingdom,
becomes more and more apparent; the durable skeletons or polyparia
being the only materials from which the palæontologist can gather
information, relating to the physiology of the extinct coral-animals
which swarmed in the ancient seas, and whose petrified remains
constitute a large proportion of the secondary and palæozoic calcareous
rocks.
Numerous fossil genera have been established by various authors from
the external form of the polyparium, or the disposition and structure
of the cells; but a slight attention to this department of palæontology
will disclose corals which differ essentially from the typical forms,
and new genera and species will require to be added to the already
extended catalogue. The few genera selected for the present work,
will convey a general idea of the nature of this class of fossils. To
ascertain the names of the species he may collect, the student must
refer to works especially devoted to the illustration of the corals of
particular rocks; as for example, those of the British _Cretaceous_
deposits in the monographs of the Palæontological Society; of the
_Palæozoic_ in _Sil. Syst._; and in Prof Sedgwick's Synopsis of the
Classification of the Brit. Pal. Foss.; of the _Mountain Limestone_
in Prof, Phillips's work; and those of Ireland in Col. Portlock's
Geological Memoirs. Those of the palæozoic rocks of New York, are
illustrated in Prof. James Hall's splendid work on the Geology of that
State.
The fossil zoophytes included in this section present innumerable
varieties of form and structure, but agree in the important character
of having originated, (with but few exceptions,) from aggregations
of those minute beings termed Polypes (many-feet[229]). The common
Hydra (_Wond._ p. 600), or fresh-water polype, that inhabits pools
and streams, is a familiar example of a free animal of this kind,
consisting of a cellular gelatinous substance, in the form of a short
tube, or pouch, surrounded at the upper margin by long tentacula,
or feelers, which appear to the naked eye as delicate threads. The
_Polypifera_, properly so called, are groups of polypes, permanently
united by a common integument or axis, each animalcule having an
independent existence. A common support or endo-skeleton, termed
_polyparium_,[230] is secreted by the integuments, which varies in
its nature from a mere gelatinous, or horny material, to an earthy,
calcareous, and even siliceous substance, that remains when the polypes
die, and their soft parts have perished. All the varieties of corals,
&c. are nothing more than the durable structures of aggregated masses
of such beings.
[229] A name derived from the tentacula, or processes, which in some
species serve for prehension, and in others for respiration.
[230] The basis, framework, or endo-skeleton, of these groups
of animalcules is termed the _polyparium_, or _polypidom_
(polype-habitation); those of a stony hardness are familiarly known as
corals; these names, therefore, refer to the durable substance, and not
to the animals themselves; but in familiar writing, the term Coral is
often used to designate the entire living mass. The Red-Coral forms a
distinct genus called _Corallium_. In fossils, the _polyparium_ alone
remains, except in very rare instances.
It may here be necessary to notice a prevailing error, regarding the
mode in which the substance called coral is produced. It is very
generally supposed that Corals, particularly those bearing stars and
cells, have been constructed by animalcules, in the same manner as
is the honey-comb, by the Bee; and the expressions often employed
by naturalists, of "the coral animalcules building up their rocky
habitations," and "constructing their cells," have contributed to
foster this error. But the processes are in no respect similar: the
insect, under the guidance of an unerring instinct, resulting from
its peculiar organization, _constructs_ its cells; but the polype is
incapable of forming, or even modifying, its support or cell in the
slightest degree. The polypidom is _secreted_ by the animal tissues, in
the same manner as are the bones in the vertebrated animals, without
the individual being conscious of the process. If a piece of white
coral be immersed in dilute hydrochloric acid, the calcareous part is
dissolved, and the secreting membrane, in the form of a flocculent
substance, is seen attached to the undissolved part; even in some
coralline marbles of incalculable antiquity, the animal membrane may,
in this manner, be detected.[231]
[231] See Pict. Atlas, pl. xxxiv. _fig._ 2.
From the delicate and perishable nature of many of the gelatinous
zoophytes, numerous tribes may have inhabited the seas, which deposited
the fossiliferous strata, and yet no indications of their existence
remain; while, of others, but obscure traces of their structure are
likely to be detected.
The Polypifera are separated into two natural groups or classes; viz.
the Anthozoa (flower-animals), and the Bryozoa (moss-animals), or
Polyzoa.
The Anthozoa are polypes of the most simple type of structure. The body
consists of a symmetrical gelatinous sac, capable of contraction and
expansion, with one aperture or mouth, which is encircled by tentacula.
The Hydra, or fresh-water polype (_Wond._ p. 600), is a familiar
example of a single, locomotive, anthozoan animal. In the compound
or aggregated forms, the body is either inclosed in a horny sheath
(ex. _Sertularia_, _Wond._ p. 615), or is supported by a lamellated
calcareous endo-skeleton (ex. _Fungia_, _Wond._ p. 623, pl. vi. _fig._
15), or the soft parts invest a stony axis (ex. _Madrepora_, _Wond._ p.
620), or a horny flexible framework (ex. _Gorgonia_, _Wond._ p. 616).
The Anthozoa are subdivided into three orders, which are based on
the peculiar characters of the polypes; the _Hydra_, the _Actinia_
(Sea-Anemone, _Wond._ p. 622), and the _Alcyonium_ (Dead-men's fingers,
_Wond._ pl. v. _fig._ 10), being respectively the type of 1. the
_Hydroida_, or Hydraform; 2. the _Asteroida_ or Alcyonian; and 3. the
_Helianthoida_, or Actiniform zoophytes.
In the Hydroida the body in the compound species is implanted in a
horny tubular sheath, and the polypidoms form branched corallines,
which are fixed by the base to rocks, sea-weeds, shells, &c.
The Asteroida have a horny or calcareous axis, surrounded and inclosed
by the soft parts which secrete it.
The Helianthoids, except in the simple free species, as the Actinia,
have a lamellated calcareous polypidom, the plates of which radiate
from a centre.
The calcareous secretions of the Anthozoa, especially of the
Helianthoida, in a great measure constitute the mass of the coral-reefs
and coral-islands of tropical seas. Their polypidoms, whether external
or internal, maintain but little organic connexion with the compound
soft substance. These zoophytes increase by gemmation or budding; some
throw up germs from the disk, as in Astreadæ; others laterally, as in
Caryophillidæ; and some spirally along the stem, as in Madreporidæ;
examples of these modes of reproduction are often found in fossil
corals. The increase of coral-rocks is produced by the continual
formation of new masses, by the successive generations which spring up
as it were from the bodies of their parents; layer upon layer, and tier
upon tier, of Helianthoid polypidoms, are found to compose many of the
coralline limestones of the palæozoic formations.
Fossil Anthozoa.--The first group of extinct corals to be noticed under
this head is the _Graptolitidæ_, a family restricted to the Silurian
rocks, and whose natural affinities have been much questioned; some
palæontologists referring them to the _Pennatulidæ_, or Sea-pens,
others to the _Sertulariadæ_.[232]
[232] For a full consideration of this subject, refer to Prof. McCoy's
Brit. Palæozoic Fossils.
[Sidenote: GRAPTOLITES.]
[Illustration: Lign. 85. Graptolites in Wenlock Limestone.
(_Murch. Sil. Syst._)
Fig. 1.--Graptolites ludensis.[233]
1_a_.--Magnified view of a portion of the same.
2.--Graptolites Murchisoni.
2_a_.--Magnified portion of _fig._ 2.
]
[233] _Ludensis_, from Ludlow--to indicate the habitat of the fossils.
Graptolites. _Lign. 85._--These curious zoophytes abound in many of
the Silurian deposits; they consist of sessile polype cells, arranged
in one or two rows to a flexible stem, like the recent Sertularia, or
Virgularia. Prof. McCoy refers them to the order Hydroida.
In a recent state these bodies were probably covered with a soft, or
albuminous mass, studded with polype-cells, disposed in rows along
the margins of the lateral, curved, grapple-like processes, as in the
zoophytes termed _Virgularia_,[234] to which one kind bears a great
analogy. If two specimens of the _Graptolites Ludensis_ be placed
together, so that the elongated smooth edges be in apposition, the
united stems will be seen to offer a general resemblance to the axis of
_Virgularia mirabilis_.
[234] See British Zoophytes, pl. xxiv.
M. Barrande divides the Graptolites into three groups or genera, which
are defined as follow:--
_Graptolites_ (proper), a single series of cells united together at the
base, and adhering along the sides nearly to the orifice of each cell,
as in _fig. 1a_. _Monoprion_ of M. Barrande.
_Rastrites._--The axis reduced to a mere line, on which the cells are
placed at relatively wide intervals, and but slightly inclined. These
two genera are supposed to have been hydroid zoophytes, and related to
the Sertularidæ.
_Diprion_ (_Diplograpsus_ of Mr. McCoy), cells in two series arranged
along a central axis; these forms present a foliaceous appearance; they
are presumed to resemble the existing genera Pennatula and Virgularia.
Graptolites have been found in strata of the same age in Norway,
Sweden, and Scotland.[235] I have received slates literally covered with
them, from the Silurian rocks of the United States, by the kindness of
my friend, Benjamin Silliman, jun. Esq.
[235] Many species of Graptolites from the Lower Silurian rocks of the
South of Scotland, are described and figured by Mr. Harkness in Geol.
Journal for 1850, vol. vii. p. 58, pl. 1.
Sir R. Murchison remarks, that the nature of the strata in which these
remains occur in Radnorshire, indicates a condition of the sea, well
suited to the habits of the family of Pennatulidæ, or Sea-pens; for
the recent species live in mud and slimy sediment, and the fossils are
imbedded in a finely levigated _mud-stone_, which, from its structure,
must have been tranquilly deposited.
* * * * *
I will next describe the single lamellated Anthozoa, and afterwards
notice those corals which consist of an aggregation of radiated cells,
either frondescent, or disposed in solid masses.
[Sidenote: FUNGIA. ANTHOPHYLLUM.]
Fungia (_Wond._ p. 623).--The corals thus named, from their supposed
resemblance to fungi, are of a depressed form, and have the under
surface scabrous; they are divided above by numerous lamellæ, or
plates, which radiate from a central, oblong depression.
When living, the solid stony polyparium is enclosed in the gelatinous
mass by which it was secreted, and there are numerous tentacula
around the central cavity, or sac. These zoophytes may be compared
to the _Actiniæ_, or Sea-Anemones, from which they differ only in
having a calcareous axis, while the Actiniæ have a tough albuminous
integument. (_Wond._ pl. vi. _fig._ 15, represents the living animal;
and _Lign. 141, fig. 2_, p. 641, and _Lign. 58, fig. 4_, two fossil
species).[236]
[236]
Fungia numismalis. Pict, Atlas, pl. xxxvi. _fig._ 6.
------ polymorpha. Ibid. pl. xliii. _fig._ 1--4; pl. xlv, _fig._ 11.
Anthophyllum Atlanticum. _Lign. 88. fig. 4._--In the arenaceous
strata of the United States, which the researches of Dr. Morton,
of Philadelphia, have proved to be the equivalents of the European
Cretaceous formation, a single lamellated coral is not uncommon. It is
evidently related to the Fungiæ, and has been named as above by Dr.
Morton.
Turbinolia Königi (_Wond._ p. 320).--Polyparium turbinated, striated
externally, detached, base not adhering; cell single, radiated.
This genus occurs in all the fossiliferous deposits: a small,
well-marked species is frequently met with in the Galt, of which
subdivision of the cretaceous strata it is a characteristic fossil. It
is figured _Wond._ _Lign. 58, figs. 1, 2_.[237]
[237]
Turbinolia complanata. Ibid. pl. xxxvi. _fig._ 9.
---------- mitrata. Ibid. pl. xxxvi. _fig._ 10.
Caryophyllia centralis (_Lign. 89 figs. 1, 2_: _Lign. 88, fig.
5_).--Polyparium turbinated, or cylindrical, simple or branched,
longitudinally striated, fixed by the base; cells lamellated.[238]
[238] Monocarya (of Lonsdale), Dixon's Fossils, p, 244.
A small recent species (_C. cyathus_), is very common in the
Mediterranean, and frequently seen in collections: it is cyathiform,
and the base by which it is attached to other bodies, is broad and
spreading; the newer tertiary deposits of Sicily contain this species
in abundance.
A Caryophyllia, bearing a general resemblance to this species, is
common in the chalk, and occurs in beautiful preservation (_Wond._
_Lign._ 58, _fig._ 3).[239]
[239]
C. centralis, Pict. Atlas, pl. xxxvi. figs. 15, 16.
C. annularis, ibid. pl. xxxvii. _fig._ 5.
Branched Caryophylliæ are found in the Coralline Oolite and Dudley
Limestones (_Sil. Syst._ pl. xvi.). A large proportion of the Coral-rag
of the Middle Oolite is composed of a branched species (_C. annularis_)
of this genus; _Lign. 88, fig. 5_, represents a specimen from near
Faringdon.
[Illustration: Lign. 86. Favosites polymorpha. (Goldfuss.)
_Devonian limestone. Eifel._
Fig. 1.--Portion of a branch of the coral; _nat._
2.--Fragment, slightly magnified, with part of the surface broken
away below, exposing the central axis, and radiated
arrangement of the cells, with their lateral pores.
3.--Another portion, magnified, showing the polype-cells hollow.
]
Favosites polymorpha. _Lign. 86. Lign. 88, fig. 3._--Polyparium
stony, polymorphous, solid internally, compact, composed of a
congeries of diverging or ascending parallel, contiguous, prismatic
tubes, covered by pores, divided by lamellæ, and communicating by
lateral foramina.
The corals of this extinct genus abounded in the Silurian and Devonian
seas; the remains occur with those of other fossil zoophytes of that
epoch in great numbers, both in Europe and North America. I have many
beautiful examples from the Silurian rocks of the Ohio and Niagara, by
favour of Dr. Owen, of New Harmony, and Dr. Yandell, of Louisville, in
which the cells are filled up with calcareous spar. The varied markings
on many of the Babbicombe marbles, and Torquay pebbles, are derived
from the enclosed Favosites (_Wond._ p. 643).
Another species (_Favosites Gothlandica_) occurs in masses of a
subconical shape, and is common in some of the Silurian limestones. A
fragment, to show the structure, is figured _Lign. 88, fig. 3_.
[Sidenote: CATENIPORA. SYRINGOPORA.]
Catenipora (_Wond._ p. 644, _fig._ 3).--Polyparium hemispherical,
composed of vertical anastomosing lamellæ; cells tubular, oval,
terminal, united laterally. The oval form of the cells when united
laterally, and the flexuous disposition of the lamellæ, give rise
in transverse sections to elegant catenated markings, from which
appearance the fossil has received the name of _chain-coral_.[240] The
species figured (_C. escharoides_) in _Wond._ is common in the Silurian
limestones, and sometimes forms hemispherical masses more than a
foot in diameter. The chain-coral is extensively distributed through
the Silurian rocks of the United States. Coloured figures of this
exquisitely beautiful coral are given in _Pict. Atlas_, pl. XXXV.
[240] Org. Rem. vol. ii. pl. iii. figs. 4, 5, 6.
Syringopora ramulosa. _Lign. 88, fig. 2._ (_Wond._ p. 641.) These
corals bear a general resemblance to the Organ-pipe Coral of Australia.
The polypidom is composed of long, cylindrical, vertical tubes, distant
from each other, and connected by transverse tubular processes; the
cells are deep and radiated by numerous lamellæ.
The external aspect of these fossils is that of a cluster of
cylindrical pipes, more or less parallel, connected by short transverse
branches. They are the _Tubiporites_ of Mr. Parkinson, who has given
admirable figures of several specimens.[241] In these fossil corals
that excellent observer first detected the animal membrane. A slab of
marble, whose markings are produced by the section of the inclosed
tubes of a Syringopora, is represented, _Wond._ p. 644, _fig._ 2. The
Mountain limestones of Derbyshire, and of Clifton, on the banks of the
Avon, contain figured marbles of this kind, which are manufactured into
vases, tables, &c. The genus is extinct.
[241] Pict. Atlas, pl. xxxv. _fig._ 1. Syringopora geniculata, Pict.
Atlas, pl. xxxiv.
Lithostrotion Columnaria (_Wond._ p. 641, _fig._ 8).--Polyparium
massive, solid, composed of aggregated, contiguous, parallel, prismatic
tubes, each terminated by a star: cells shallow, multi-radiate,
stelliform.
Species of this extinct genus are common in the mountain limestone, in
large masses, which, from the pentagonal form, and parallel arrangement
of the tubes, appear like clusters of miniature basaltic columns.[242]
[242] Lithostrotion striatum, Pict. Atlas, pl. xxxvii. figs. 5, 6.
[Sidenote: CYATHOPHYLLUM.]
Cyathophyllum. _Lign. 87, figs. 1, 2._ (_Wond._ p. 641, _figs._ 1,
3.)--Polyparium turbinated, simple or compound, internal structure
transversely chambered or lamellated; cells polygonal, radiated,
depressed in the centre.
The corals of this genus are so abundant in the Silurian rocks,
that the seas of that epoch must have swarmed with them. The simple
turbinated forms are often several inches long, and being somewhat
curved, have obtained the popular name of "_petrified rams-horns_."
Upon slitting one of these corals vertically, as in _Lign. 87, fig.
1_, the axis of the polyparium, beneath the cell, is found to consist
of thin transverse partitions, constituting a series of chambers.
In the compound Cyathophylla, the germs of young cells, occupying
the disc of a parent cell, are often met with. _Fig._ 3 represents a
group of four germs on the parent cell, of _C. dianthus_, a common and
beautiful coral of the Dudley limestone.
[Illustration: Lign. 87, Corals from the Dudley Limestone.
(_Sil. Syst._)
Fig. 1.--Cyathophyllum turbinatum: an oblique longitudinal section,
showing at a the transverse lamellæ, or cells, of the internal
structure.
2.--The same species.
3.--Cyathophyllum dianthus: a Specimen, with four young germs
arising from the disc below.
4.--The same species, with four adult cells.
]
These corals are also prevalent in South Devonshire, and many of the
elegant marbles of Babbicombe are figured by the sections of these
polyparia.[243]
[243]
Cyathophyllum turbinatum, Pict. Atlas, pl. xxxvi.
------------- fungites, ibid. pl. xxxviii.
Associated with the Cyathophylla in the Silurian rocks, are certain
corals that attain considerable magnitude, and which are principally
distinguishable by their internal structure. Such are _Cystiphyllum_,
constructed of bladder-like cells, and _Strombodes_, composed of
spirally contorted lamellæ, or plates (_Sil. Syst._ pl. 16^(bis),
_fig._ 4). Other hemispherical masses, presenting on the surface
concentric wrinkles, with very minute pores, are common at Dudley, and
belong to the genus _Stromatopora_.
[Illustration: Lign. 88. Fossil Corals.
_Upper Silurian, Dudley._[244]
Fig. 1.--Astrea ananas.
1_a_.--A polished slice of Marble, formed of Astrea pentagona.
_Devonian. Torquay._
2.--Syringopora ramulosa. _Mt. L. Derbyshire._
3.--A Fragment of Favosites Gothlandica. _Ohio._ (_By Dr. Owen._)
4.--Anthophyllum Atlanticum. _Cret. U. States._ (_By Dr. Morton._)
5.--Caryophyllia annularis. _Oolite. Faringdon._
]
[244] Figured in Pict. Atlas, pl. xxxvii. _fig._ 1.
[Sidenote: ASTREA.]
Astrea. _Lign. 88, figs. 1, 1a._--Polyparium massive, irregular
in shape, generally globular, formed by an aggregation of lamellated,
radiated, shallow, polymorphous cells.
The corals of this genus are very numerous in the seas of the Tropics,
and there are many species in the Oolite, and older secondary
formations. The Astreæ, Caryophylliæ, Cyathophylla, &c., form the
principal mass of the coralline limestones of the Oolite, termed the
_Coral-rag_, from the abundance of these relics: being literally
composed of an aggregation of large corals, the interstices of which
are filled with shells, radiaria, &c., either whole, or in a comminuted
state. The heaps of this limestone placed by the road-side, in the
N. W. of Berkshire, appear like fragments of an old coral-reef, and
attract the notice even of the most incurious observer. I have figured
a specimen of Astrea, _Lign. 88, fig. 1_, and a polished section,
_fig. 1a_, from Clifton, a locality well known for the stupendous
mural precipices of mountain limestone rocks, which yield beautiful
examples of coralline marble.[245] The mode of increase of the Astrea
is very curious; a subdivision takes place in the old cells, after the
manner of the Infusoria; and among the fossils, a star or cell may
often be seen in progress of division into two, three, or four stars
(_Sil. Syst._ pl. xvi. _fig._ 6). A living polype of this genus is
figured, _Wond._ pl. vi. _fig._ 13.
[245]
Astrea arachnoides, Pict. Atlas, pl. xxxviii. _fig._ 4.
------ undulata, ibid, pl. xxxviii. _fig._ 10.
------ Tisburiensis ibid. pl. xxxviii. figs. 12, 13.
A species of Astrea (_A. Tisburiensis._ _Wond._ p. 641, _fig._ 9), is
found in large hemispherical masses, completely silicified, at Tisbury,
in Wiltshire. The transverse surface displays, in some specimens,
beautiful white radiated stars, on a dark blue ground; and in others,
the colours of the stars and ground are reversed. This silicified
coral is obtained from a bed of chert, a foot in thickness, which is
interstratified with the Portland limestone, this division of the
Oolite being quarried around Tisbury.[246]
[246] See Catalogue of the Organic Remains of Wiltshire, p. iv. by Miss
Etheldred Benett. 4to. 1831.
In the tertiary clays at Bracklesham Bay, Sussex, a beautiful small
coral of this type (_Siderastrea Websteri_, Dixon's Foss. tab. i, 5),
is found attached to flint pebbles.
Several species of this and the following genus, perfectly silicified,
are found in the state of pebbles and boulders in the superficial soil
of Antigua, and other islands of the West Indies, associated with the
fossil palms, described in a former part of this work. Some of these
corals are of great beauty, and polished sections exhibit the coralline
structure most perfectly.[247]
[247] In the "Spongitenkalk," at Nattheim, near Heidenheim, all the
corals are replaced by chalcedony.
Madrepora.--Polyparium arborescent or frondescent, porous, fixed;
cells deep, with twelve rays, prominent, irregularly dispersed on the
surface, and accumulated towards the terminations of the coral.
The term madreporite, or fossil madrepore, was formerly applied to all
the branched fossil corals with radiated cells, but is now restricted
to those which possess the above characters. The recent common species,
figured _Wond._ p. 620, will serve to illustrate this genus. The
elevated, branched Madrepores, with minute polygonal cells having
twelve rays, the lamellæ of which are denticulated, are termed Porites,
and are frequent in the Silurian strata (_Sil. Syst._).
Millepora. _Lign. 89._--Coral ramose; cells very minute, distinct,
perpendicular to the surface, giving the interior a finely striated
fracture, disposed irregularly.
There are many fossil species of this genus, some of which are of
considerable size. A small species from the mountain limestone is
figured _Lign. 89, fig. 7_.[248]
[248] Millepora, Pict. Atlas, pl. xl. _fig._ 6.
Lithodendron. _Lign. 70, fig. 3._--Polyparium branched, formed of
deep, cylindrical, elongated cells, which are terminal, and radiated,
with a prominent central axis.
Large masses of corals of this genus, composed of clusters of
branches, are imbedded in the mountain limestone of Derbyshire,
Yorkshire, &c.; and a few species occur in the Coralline Oolite; their
general configuration will be understood by the figure _Lign. 70,
fig. 3_; but in this specimen the margins of the cells are worn off,
and do not present the original deeply excavated form.[249]
[249] Lithodendron fasciculatum, Pict. Atlas, pl. xxxviii.
There is a remarkable specimen of this coral in the Bristol Institution
(of which a portion is now placed in the Museum of Practical Geology,
in London), that was discovered by Mr. Samuel Stutchbury,[250] in a
vein of hematitic iron ore. It is a large mass, in which the entire
substance of the coral is transmuted into a metallic ore, forming one
of the most interesting natural electrotypes I have ever seen. In
this instance, a block of Lithodendron must have lain in a vein or
fissure of the rock, and its animal membrane have resisted the action
of the gaseous emanations, or mineral solutions, while the calcareous
polypidom was dissolved, and the metallic matter deposited atom by
atom, as in the case of pseudo-morphous crystals.
[250] Now of Sydney, Australia.
Gorgonia.--Of the flexible anthozoan coral, which from the flabellated
form of the polyparium is generally called "Venus's fan," and by
naturalists _Gorgonia_, a few fossil species have been discovered and
determined. From the friable arenaceous limestone beds of Maestricht,
which abound in corals, fine specimens of a delicate species are
occasionally procured. _Wond._ p. 320, _fig._ 5, shows the character of
this fossil zoophyte.
Fossil Bryozoa.
[Sidenote: FOSSIL BRYOZOA.]
The second class of Polypifera, the Bryozoa or _Polyzoa_, are of a
much higher order of organization than those which have engaged our
attention. The body is not symmetrical, nor capable of contraction and
expansion, as in the Anthozoa: it consists of a digestive cavity or
sac, which is bent on itself and open at both extremities. The outer
integument is either membranaceous or horny; sometimes calcareous. The
oral aperture or mouth is surrounded by a circle of tentacula, from
eight to twelve or more in number, and these tentacles are clothed with
vibratile cilia. (_Wond._ p. 606, the polype of _Flustra pilosa_.)
The polypes in this order never occur singly; they are always united
by a common integument, but each enjoys an individual existence. The
animal can extend its tentacula and protrude the mouth from the cell,
but the rest of the body is incapable of extension or contraction.
These polypifera increase by germination. In their organization,
they so closely approach the mollusca, that in recent zoological
systems they are placed in that class. The ciliated character of
their tentacula has also led to their being named _Cilio-branchiata_.
But as it is desirable in a work of this elementary nature to avoid
conflicting opinions as much as possible, the fossil Bryozoa will be
considered as corals, in the general sense of that term.
[Sidenote: FLUSTRA. ESCHARA.]
Flustra (_Sea-mat_). _Lign. 89, fig. 4, 5._--The polyparium is
either membranaceous and flexible, calcareous and encrusting, or
foliaceous, composed of cells, arranged in juxtaposition, more or less
quadrangular, flat, with a distinct border, disposed on a flat surface,
or on opposite surfaces, as in the _F. foliacea_.
This is one of the most common genera of the encrusting and frondescent
zoophytes. The _Flustra_ consists of a cluster, or aggregation of
polypes, invisible to the naked eye; under the microscope, the polype
is found to be a transparent gelatinous body bent on itself, with a sac
or digestive cavity, having two apertures, the external margin of which
terminates in eight or ten tentacula, clothed with cilia; the whole is
surrounded by a firm wall, constituting a cell, from which the animal
can protrude its tentacula and upper part. (Figures of the living
polypes of Flustræ, _Wond._ p. 605, _pl._ vi. _fig._ 6, 7.)
Many species of _Flustræ_ occur in the British strata: the encrusting
forms are attached to echinites, shells, &c.; the foliaceous are
imbedded in chalk, sand, sandstone, &c. In Mr. Morris's _Cat. Brit.
Foss._ ten species are enumerated; none of these are from formations
below the Chalk. I have selected for illustration a Flustra attached
to an echinite from Lewes. _Lign. 89, fig. 5_, represents a small
portion of the natural size; and _fig. 4_, a few cells magnified, to
show their form and arrangement. A foliaceous zoophyte, apparently a
bryozoon, is abundant in the Sussex and Kentish chalk, and is often
disposed in angular folds. It is generally of a ferruginous colour,
and, from its friable texture, it is probable the original consisted
of a membranous polypidom or calcareous substance; specimens sometimes
extend over several square inches of the chalk. It is common in the
chalk-pit at Off ham, near Lewes.[251]
[251] In my South Down Fossils, pl. xv. _fig._ 6, a specimen of this
kind is described as a Ventriculite, _V. quadrangularis_. An admirable
lignograph of a remarkable example is given by Mr. Toulmin Smith, under
the name of _Brachiolites angularis_; it presents ten deep, flat,
angular folds, and has radicle and lateral processes; see "On the
Ventriculidæ," p. 93.
Eschara.[252]--In these zoophytes the polyparium is encrusting or
foliaceous, calcareous and brittle; the cells are thickened on their
outer margins, and have a small, depressed, round aperture. They are
arranged in two series of planes, adhering together, the cells on each
surface exactly corresponding.
[252] So named from a supposed resemblance to an eschar.
Species of Escharæ are found either in flints, or attached to
echinites, and other bodies; they have the appearance of patches of
flustræ, but with a lens may be distinguished by the symmetrical
juxtaposition of the cells on the opposite sides of the polyparium.
[Illustration: _Ellen Maria Mantell, ad nat. delt._
Lign. 89. Corals from the Chalk and Mountain Limestone.
Fig. 1.--Carophyllia centralis; _nat._ (G. A. M.) _Cret. Lewes._
2.--Front view of half the disc of the same.
3.--Two cells of Crisia Johnstoniana. × ×.
4.--Magnified view of six cells of the Flustra, _fig._ 5.
5.--A portion of an encrusting Flustra; _nat._ _Cret. Chichester._
6.--Idmonea (Dixoniana) cretacea; _nat._ _Cret. Lewes._
The figure on the left shows the under surface; that on the
right, the upper surface, with a row of polype-cells on
each margin: a portion magnified is given _fig._ 12.
7.--Millepora rhombifera. × ×. _Mt. L. Ph. Yorks._
The small figure on the left is of the natural size.
8.--Pustulopora pustulosa. × ×. _Cret. Chichester._
The small figure on the left, _nat._
9.--Homœsolen ramulosus. × ×. _Cret. Dover._
The left-hand figure, _nat._
10.--Crisia (?) Johnstoniana. (G. A. M.) × 250 linear.
_S. s. Maidstone._
10_b_.--Two cells of the coral, _fig._ 10, seen in profile, × ×.
11.--Homœsolen ramulosus; _nat._ _Cret. Lewes._
12.--Idmonea Dixoniana; a portion of _fig._ 6. ×.
13.--Retepora laxa. _Mt. L. Ph. Yorks._
13†.--A portion of the same ×.
14.--Idmonea Comptoniana. × ×. (G. A. M.) _Chalk, Chichester._
(_Mr. Walter Mantell._)
The small figure on the right is of the natural size.
]
[Sidenote: MICROSCOPIC FOSSIL BRYOZOA.]
Crisia Johnstoniana. _Lign. 89, fig. 3, 10, 10b._--The minute
recent corals thus designated are allied to _Flustra_, but separated
from that genus by the cells being disposed in a single series, and
united by connecting tubes. I notice this genus to direct attention to
a very curious polypidom from the Greensand of Maidstone, presented to
me by Mr. Bensted. The specimen is attached to a fragment of shell. The
cells, five of which are represented, _fig._ 10, are elliptical, with
the aperture above, and towards one extremity; they are united by very
slender, hollow filaments: _fig. 3_, two of the cells seen from above
× 250 linear; _fig. 10b_ the same seen in profile.[253] I have named
this species _C. Johnstoniana_, as a tribute of respect to the author
of the admirable works on British Zoophytes, previously noticed.
[253] I refer this fossil to the genus _Crisia_ with some hesitation;
perhaps _Hippathoea_ would be more correct, but all the described
species of the latter are branched.
The fragmentary relics of numerous minute and elegant corals,
constitute a considerable portion of the mass of some of the white
chalk strata; several genera of these zoophytes are figured in Mr.
Dixon's beautiful work, and described by Mr. Lonsdale. Attached to
the surface of shells, &c., and sometimes standing erect in little
crannies, or hollows, of the flints, many beautiful corals may often be
detected with the aid of a lens. By brushing chalk in cold water, and
examining the deposit, the student will probably discover several of
the species figured in _Lign. 89_, which we proceed to describe.
Retepora (_Lace-Coral_). _Lign. 89, fig. 13._--A very thin calcareous
polyparium, disposed like net-work in foliaceous and branching plates;
cells opening either on the upper or inner side.
These are an elegant tribe of corals, of which many species occur in
the Chalk formation at Maestricht, in the white-chalk of England,
in the mountain limestone of Yorkshire, (_Phil. York._), and in
the Silurian deposits (_Sil. Syst._). It may be useful to state,
that in the description of the fossil retepores, the openings in
the net-work are called fenestrules--the spaces between the ends,
_dissepiments_--and those between the fenestrules, interstices. A
delicate fossil retepore from the mountain limestone of Yorkshire (_R.
flexa_), is figured _Lign. 89, fig. 13_.
Fenestrella.--Cells very small, indistinct externally, with small
prominent openings; polyparium stony, fixed at the base, composed of
branches, which inosculate by growth, and form a cup. Numerous delicate
corals, formerly arranged as _Reteporæ_, occur in the Silurian rocks,
and have been placed in this genus by Mr. Lonsdale. (_Sil. Syst._ p.
677.)
Petalæpora pulchella.[254] _Lign. 69, fig. 1._--This beautiful
cretaceous coral is "tubular, free except at the base; framework
composed of vertical laminæ, with an intermediate foraminated
structure; apertures to the tubular cavities distributed over the
surface; exterior varying with age." It has slender round dichotomous
branches, and the polyparium when entire must have formed an elegant
plexus of coral. A layer an inch thick, full of branches of this
zoophyte, is exposed on the face of the chalk cliffs, near Dover; and
beautiful masses, several inches square, made up of this coral, Idmonea
and Pustulopora, may be obtained. The microscopic specimen figured in
_Lign. 69_, was obtained with many other corals by washing chalk with a
brush, and examining the detritus deposited.
[254] Mr. Lonsdale. Dixon's Fossils, p. 285.
Pustulopora. _Lign. 89, fig. 8._--Another very common tubular
branched coral of the Dover chalk; the tubes are cylindrical, their
apertures are arranged in annular or spiral rows, and slightly
projecting, giving a pustulous appearance to the stem and branches.
Specimens covering a piece of chalk six or eight inches wide, and a
foot long, have been discovered. The example figured is a very minute
branch.
Homœsolen ramulosus.[255] _Lign. 89, figs. 9, 11._--This delicate
branched coral is formed of large and small tubes variously
intermingled, both inclined in the same direction, partially visible
on the surface, or wholly concealed, limited to one side of the coral;
mouths simple tubular extremities; back without pores, composed of a
continuous lamina.[256]
[255] Homœsolen, from ομοιος, similar; and σωλην, a tube.
[256] Mr. Lonsdale, in Dixon's Fossils, p. 307, tab. xviii. B. figs, 3,
4, 5.
The elegant coral, _fig. 11, Lign. 89_, is thus named by Mr.
Lonsdale; it resembles his _fig. 4_. The fossil, _fig. 9, Lign.
89_, though very different in its branching, and in the surface, which
is covered with pores, is evidently identical with _fig. 3_ of Mr.
Lonsdale, which he refers to the same species.
Idmonea, _Lign. 89, fig. 6._--In this elegant coral the polyparium is
calcareous, branched, porous; the cells distinct, prominent, arranged
in single rows, more or less inclined, on each side a median line on
the inner face only. The genus is extinct.
A beautiful species of Idmonea, of which a small branch is figured in
_Lign. 89_, abounds in the chalk of Kent and Sussex; it often forms a
cluster, two or three inches in circumference. The surface of the stems
is covered with minute pores, and the cells are distinct, and placed in
single rows; the left-hand figure of _fig. 6_ shows the plain surface,
and that on the right, the opposite and inner, each margin of which
is garnished with a row of cells; a portion magnified is represented
_fig. 12_.[257]
[257] In the former edition of this work, I named this species _I.
Dixoniana_, to commemorate the researches of my late friend, Frederic
Dixon, Esq., of Worthing, who had formed an interesting collection
of chalk fossils, and announced a work on the "Zoology of the Chalk
Formation," to be richly illustrated with figures of many undescribed
organic remains. It appears that a species, supposed to be identical,
had been previously named by Mr. Milne Edwards, _I. cretacea_. See
Dixon's Foss. tab. xviii. A. _fig._ 5, p. 281. Mr. Lonsdale places it
in a new genus, with the name of Desmeopora semicylindrica. It will
convey some idea to the unscientific reader, of the labour bestowed
on this department of palæontology, to learn that the description and
identification of but 25 species of minute corals, represented on three
plates, occupy ninety pages of close printing in royal 4to. of Mr.
Dixon's work.
Idmonea Comptoniana,[258] _Lign. 89, fig. 14._--This is a very small
and remarkable coral; it is dichotomous, cylindrical, with elongated
distinct cells, which are disposed in triplets, at regular distinct
intervals, on one side of the stem.
[258] This specific name is in honour of the noble and highly respected
President of the Royal Society, the Marquess of Northampton. 1844.
We have now described all the fossil corals figured in _Lign. 89_; and
have shown what interesting organisms may be detected in a few grains
of calcareous earth. It would be easy to give restored figures of the
beings whose stony skeletons are the subject of these remarks, from
their close resemblance to existing species; every pore and cell might
be represented fraught with life; here the agile inmates, with their
little arms fully expanded, and in rapid motion; there retreating
within their recesses, and devouring the infinitesimal living atoms
that constitute their food; or rapidly shrinking up their tentacula
upon the approach of danger; even their varied colours might be
introduced, and thus the beautiful and highly interesting picture drawn
by the imagination, of a group of living zoophytes of the ancient chalk
ocean, be presented to the eye.
Although, for convenience, I have selected the above examples
principally from the cretaceous strata, the reader must not suppose
that other deposits are not equally prolific in these remains. The
Coral-rag of the Oolite, many beds of the Mountain limestone, and
those of Dudley and Wenlock of the Silurian System, contain myriads
of minute polypidoms associated with the coralline masses of which we
have already treated. Exquisite figures of the Silurian corals, by Mr.
Scharf, are given in _Sil. Syst._ pl. xv. xvi. and described by Mr.
Lonsdale. A slab of the Dudley limestone often has the entire surface
studded with minute corals of many species and genera, lying in bold
relief, and in an admirable state of preservation.
Verticillipora (_Lign. 70, fig. 4. Lign. 72, fig. 3_).--Cells
poriform, arranged in meshes on the surface of convex imbricating
plates round a hollow axis, forming a fixed, irregular, subcylindrical
polyparium. _Lign. 70, fig. 4_, represents a coral often met with
in the gravel-pits at Faringdon, (_ante_, p. 228,) which is referred
by Mr, Morris to this genus. It is composed of short cylindrical
anastomosing tubular branches, emanating from an expanded base, divided
internally by transverse parallel plates, covered with exceedingly
minute pores or cells, disposed in meshes; the plates surround a hollow
axis; the structure is well shown in the figure.
Lunulites. _Lign. 70._--The polyparium is stony, orbicular, convex
above, concave below; concavity radiated; convexity covered with cells,
arranged in concentric circles on diverging striæ.
A species of this coral is often found in the chalk: _Lign. 70, fig.
1_, represents a specimen from the South Downs, discovered by Mr. Walter
Mantell. The natural affinities of this genus are not determined with
precision; but I have placed it with the Bryozoa in accordance with the
opinion of M. de Blainville. It is an elegant white coral, and easily
recognized among the minute organisms of the chalk.
* * * * *
[Sidenote: DISTRIBUTION OF FOSSIL BRYOZOA.]
Geological Distribution of Fossil Zoophytes.--Although the geological
distribution of fossil zoophytes affords less striking phenomena than
that of the vegetable kingdom, yet some interesting reflections are
suggested by the facts we have thus cursorily noticed. We find that
in the most ancient seas of which any vestiges of their inhabitants
remain, these forms of vitality existed, and produced the same physical
results as at the present time; giving rise to coral-reefs, and banks
of coral-limestones, and largely contributing to the solid materials
of the crust of the globe. Nearly 400 British species are enumerated
by Mr. Morris, and the list has subsequently been greatly extended by
the labours of Phillips, Portlock, Lonsdale, McCoy, Milne Edwards, and
other eminent naturalists.
The Tertiary formations afford numerous species of Caryophylliæ,
Flustræ, Escharæ, Spongia, &c.; and the _Crag_, several genera that
are as yet but imperfectly determined. The older Tertiary, or Eocene
deposits, contain Turbinoliæ, Astreæ, Fungiæ, Meandrinæ, and species
of other genera, the recent types of which are inhabitants of tropical
seas.
The zoophytes of the British Chalk have been illustrated in detail
by Mr. Lonsdale in Dixon's Cretaceous and Tertiary Fossils of the
South-East of England; and by Dr. Milne Edwards in the Monographs of
the Palæontological Society.
In the Maestricht deposits, lamelliferous corals, as Astreæ, Fungiæ,
Meandrinæ, &c. prevail, and may be extracted from the friable
arenaceous limestones in a fine state of preservation. In the White
Chalk and Greensand of this country, the Spongites and allied genera
are abundant, and associated with Caryophylliæ, Astreæ, and many forms
of Bryozoa.
But in the cretaceous formation of England, no coral-reefs are
observable; the zoophytal remains, with but a few local exceptions,
occur promiscuously intermingled with the fishes, shells, Radiaria, and
other marine exuviæ; although many layers, or thin seams of chalk and
marl, are largely composed of the detritus of corals, like the modern
deposits of the Bermudas (_Wond._ p. 613). These phenomena are in
accordance with the lithological characters of the White Chalk strata,
and the nature of its mollusca, both of which indicate a deep sea; and
coral-reefs are only formed at moderate depths. But in regions where
the sea was shallow, during the deposition of the cretaceous rocks,
beds of coral limestone were produced; and these also contain littoral
(sea-shore) shells, associated with the usual sponges and zoophytes
(_Wond._ p. 613).
In the marine secondary formations antecedent to the cretaceous,
namely, the Lias and Oolite, coral-reefs, which appear to have
undergone no change save that of elevation from the bottom of the sea,
and the consolidation of their materials by mineral infiltrations,
demonstrate a condition of the ocean in our latitudes, which is now
only met with in the tropics (_Wond._ p. 614).
The limestones of the Carboniferous, Devonian, and Silurian formations,
abound in anthozoan corals, and among them are many kinds of
Cyathophyllum, Lithododendra, Syringopora, Catenipora, Graptolites,
&c., which are characteristic of these deposits.
The Silurian zoophytes are figured in _Sil. Syst._; and the splendid
works on the British Palæozoic Fossils, by Prof. Sedgwick and Prof.
McCoy, now in course of publication, contain many admirable figures of
new, or but imperfectly known species.
The extensive beds of coralline limestones, which are found in the
Silurian strata, wherever they occur,--for the limestones of this
system in North America are characterized by the same species of corals
as those of England,--seem to indicate that a more equal temperature
prevailed throughout the ocean, at that geological epoch, than at the
present time, when the geographical distribution of the coral zoophytes
is strictly limited by temperature. The reef-forming genera are now
confined to waters where the temperature is not below 70°; their most
prolific development being 76°. The apparent exception, the occurrence
of coral-reefs at the Bermudas, is found to depend upon proximity to
the Gulf Stream (_Wond._ p. 614), which brings down the thermal waters
of the tropics, and increases the local temperature of the sea in
those localities.[259]
[259] Mr. Deane's splendid and masterly work on Corals, should be
studied by those who wish to be acquainted with the present state of
this branch of natural history.
[Sidenote: ON COLLECTING FOSSIL CORALS.]
On Collecting Fossil Corals.--Few instructions are required for the
collection of fossil zoophytes; for as the most important characters of
the several kinds have been pointed out in the previous descriptions,
the student will be able to select illustrative specimens for his
cabinet. The minute corals, &c. of the Chalk, and other limestones, are
to be obtained by the same process as that directed for the discovery
and preservation of the foraminifera, and other microscopic organisms,
at the end of the next chapter. The larger examples should be left
attached to a piece of chalk, when practicable, and the surrounding
stone removed with a knife or graver, so as to expose as much of the
fossil as may be required for the display of its characters, without
loosening its attachment to the block. When the investing chalk is
very hard, frequently pencilling the specimen with vinegar, or dilute
hydrochloric acid, will soften the stone, and render its removal easy,
by means of a soft brush: when acid is employed, the specimen must
afterwards be well rinsed in cold water.[260]
[260] It may be well to caution the collector against employing
sulphuric acid (commonly called _oil_ of _vitriol_) for this purpose,
for a white insoluble deposit (sulphate of lime) will thus be formed
on the specimen, and its appearance irremediably injured. Many of the
fossil corals obtained from the chalk of Dover Cliffs, are so saturated
with muriate of soda, from long exposure to the spray of the sea, as
to be liable to decomposition in the course of a few weeks, and are
therefore not worth purchasing of the dealers.
The zoophytes that are in part flint, and part chalk, as the
Ventriculites, (_ante_, p. 244, _Lign. 81_,) can rarely be obtained,
except through the quarrymen who have been instructed how to extract
them from the rock. The first specimen of this kind that came under
my notice, I discovered while breaking a mass of chalk, in search
of fungiform flints; when, to my great delight, I found the fossil,
_Lign. 81, fig. 3_, by which at once, and for the first time, was
shown the connexion between the chalk specimens, _Lign. 8, figs. 1,
2_, and the flints figured in _Lign. 8, figs. 2, 3, 6, 7, 8_. Upon
showing this fossil to the quarrymen, and exciting their attention by
suitable rewards, I obtained the illustrative series now in the British
Museum.[261] Much light would be thrown on the nature of other zoophytes
of the chalk that are invested with flint, if due care were taken in
the collection of specimens, and they were examined before extracted
from the rock. Loose, delicate specimens, whether from the chalk or
tertiary strata, should be affixed with strong gum-water to cards, or
pieces of thin board, covered with coloured paper.
[261] Petrifactions, Room VI. p. 466.
The Greensand Spongites, Siphoniæ, &c. may often be extracted from the
rock tolerably perfect, by a well-directed blow of the hammer; but
fragile species should be left attached to a block, and the surrounding
stone be carefully chiselled away, so as to expose the most essential
characters.
The Faringdon zoophytes are, for the most part, encrusted by an
aggregation of minute polyparia, shells, and detritus, which may be
partially removed by washing with a stiff brush, and their cavities
cleared with a stout penknife, removing the extraneous matter by
_chipping_, not by scraping, or the surface will be injured. In this
manner the beautiful specimens figured, _ante_, p. 228, were developed.
The Corals in the hard limestones can seldom be chiselled out to
advantage; for the most part, polished sections best exhibit the form
and structure of the originals.
Weather-worn or water-worn masses of coral limestone often display
the structure of the zoophytes of which they are in a great measure
composed, in a beautiful state of sculpture and relief: the silicified
or calcified corals appearing as perfect as if fresh from the sea.
The mural rocks of coral limestone at Florence Court, the seat of the
Earl of Enniskillen, are in many parts encrusted, as it were, with
syringopora and other tubular corals, laid bare uninjured by the long
and insensible effect of atmospheric erosion. A beautiful illustration
of the old aphorism,--"Aqua cavat lapidem non vi sed sæpe cadendo,"--is
afforded by the splendid examples of cateniporæ, fungiæ, caryophillæ,
sculptured in alto-relievo on the face of the Silurian rocks over which
dash the rapids at the Falls of the Ohio.
The silicified zoophytes of the West Indies, and those from Ava and the
Sub-Himalayas, form beautiful subjects for the microscope; and chips,
or sections, should be prepared in the manner recommended for fossil
wood in the same state of mineralization.
[Sidenote: LOCALITIES OF FOSSIL ZOOPHYTES.]
British localities.--The gravels and sands of the Crag afford most
favourable sites for obtaining tertiary zoophytes.
In the London clay at Bracklesham Bay, a species of Astrea (_A.
Websteri_) is often met with attached to flints and pebbles.
In the Greensand of Atherfield, in the Isle of Wight, an elegant coral
(_Astrea elegans_) is by no means rare.
The Greensand gravel-pits, near Faringdon, in Berkshire, abound, as
already mentioned, (_ante_, p. 228,) in many kinds of sponges, and
other porifera; and the quarries of oolitic limestone in the vicinity
of that town, yield the usual corals of the Jurassic formation in great
profusion, I know of no locality richer in fossil zoophytes, than
Faringdon.[262]
[262] See Excursion, Part IV. of this work.
The quarries of that division of the Oolite called Coral-rag (as in the
north-west of Berkshire, Oxfordshire, Gloucestershire, &c.), afford the
usual corals of the Oolite.
The Oolite near Bath contains many species, and large masses of a
minute coral (_Eunomia radiata_), are abundant.
At Steeple Ashton, in Wiltshire, numerous oolitic corals may be
obtained. The silicified _Astreæ_, of Tisbury, in the same county,
deserve particular notice (_ante_, p. 263).
Clifton, near Bristol, and Torquay and Babbicombe, on the Devonshire
coast, are celebrated for their coralline marbles and pebbles; and many
of the Derbyshire limestones are equally prolific in similar remains.
The Devonian marbles are so largely employed for ornamental purposes,--
as brooches, tables, and side-boards,--that the figures produced by the
sections of the enclosed corals must be familiar to the reader.[263]
[263] Specimens of these fossil corals, either as objects of natural
history, or as ornaments, may be obtained of Mr. Tennant, 149, Strand.
Dudley, Wenlock, and Ludlow, are well known for the abundance and
variety of Silurian polyparia.
Other localities of British corals have been mentioned in the course of
this review of fossil zoophytes.
CHAPTER VIII.
FOSSIL STELLERIDÆ; COMPRISING THE CRINOIDEA OR LILY-LIKE ANIMALS; AND
THE ASTERIADÆ, OR STAR-FISHES.
The Radiata, or radiated animals, so designated because the parts of
which the body is composed are arranged around a common centre or
axis, are divided into three sub-classes; namely, 1, the _Polypifera_,
whose fossil remains were treated of in the previous chapter; 2. the
_Acalepha_, or Jelly-fishes, whose structures are so perishable as
to render it improbable that any vestiges of them will be found in a
fossil state, though imprints of the general outline of certain kinds
may possibly occur;[264] and, 3, the _Echinodermata_, comprehending
under that term the _Stelleridæ_, or Crinoids and Star-fishes, and the
_Echinoderms_, properly so called. This sub-class is the subject of the
present section; it comprises four orders, viz.
Crinoidea, or Lily-like Animals.
Asteriadæ, or Star-fishes.
Echinidæ, or Sea-urchins.
Holothuriadæ, or Sea-slugs.
[264] The impression of an Acaleph resembling an _Æquorea_ (a kind of
Medusa), is stated by M. Pictet to have been observed in a slab of
schistose rock, in Germany.
Vestiges of the Stellerida are among the earliest relics of animal
organization hitherto discovered. Many kinds of Crinoidea abound in
the Silurian rocks, and one genus of Star-fishes occurs in the same
deposits: the Echinidæ first appear in the Devonian formation.
The Echinodermata possess the radiated type of structure in an
eminent degree; especially the Asterioidæ and the Echinidæ, of which
the common Star-fish, and Sea-urchin, are familiar examples. The
external integument or skin is in many kinds protected by spines,
(hence the name Echinoderms or spiny-skin,) and perforated by numerous
foramina for the imbibition and transmission of sea-water, and for the
protection of minute soft tubular processes (called _pseudopodia_),
which constitute organs of adhesion and locomotion.
The first two orders have endo-skeletons, composed of numerous ossicula
or little calcareous bones: in the third order, the Echinidæ, the body
is inclosed in a calcareous case or shell, formed of numerous plates
closely adjusted to each other; in the fourth order, the Sea-slugs, the
body has only a tough outer integument without movable spines.
Diversified in form and external appearance as are the Invertebrata
thus grouped together, they are naturally related by their
organization. The Crinoidea may be regarded as Star-fishes fixed to one
spot by a jointed stem; the Star-fishes as free Crinoidea; the Echinidæ
as Star-fishes with the rays coalesced and united into a globular or
spherical case; and the Holothuriæ, as elongated Sea-urchins, destitute
of spines, and without a calcareous envelop.
[Sidenote: CRINOIDEA.]
Crinoidea.--The animals of this order are subdivided into families and
genera according to the number, form, and arrangement of the plates
composing the calcareous case or receptacle, and the structure of the
arms and column. In one living family, the _Comatulidæ_, the body is
free; and in one fossil genus, the _Marsupite_, the animal is capable
of locomotion through the water.
The essential character of the _Crinoidea_,[265]--so named because the
receptacle and anus of some kinds resemble when in repose a closed lily
or tulip,--are well exemplified in the recent _Pentacrinus_; the only
known living form that is identical in structure with the numerous
extinct tribes, that swarmed in the seas of the palæozoic and secondary
ages.
[265] From κρινον, _crinon_, lily, and ειδος, _eidos_, a form.
The Pentacrinus (_F. caput-medusæ_, _Wond._ p. 647), is an inhabitant
of the Caribbean Sea, and but rarely obtained; there are specimens in
the British Museum[266] and in the Hunterian Collection of the College
of Surgeons.
[266] Petrifactions, p. 77.
This animal has a long stem or column, which is composed of pentagonal
calcareous plates or ossicula, articulated to each other by radiated
surfaces, and is fixed by the base to a rock, or other firm body. The
column supports a vasiform receptacle or cup, formed of calcareous
plates in close apposition; in which the digestive and other viscera
are situated. The upper part of the receptacle is covered by an
integument in which there is an aperture for the mouth. From the margin
or brim proceed ten multi-radiate arms, which subdivide into branches
of extreme tenuity. On the upper and inner side of the arms are
numerous articulated feelers or pinnæ. The ova are situated externally
on and near the base of the arms, as in the Comatulidæ; a family of
living Star-fishes, or more properly Crinoids, which have a receptacle,
surrounded by articulated and multi-radiate arms, but are free animals,
being destitute of a column.
In the living state of Pentacrinus, the skeleton--for such are the
specimens in our museums--was of course covered and concealed by the
soft integuments and tissues by which it was secreted. The ossicula
composing the stem are pentangular, and very numerous; they have a
central perforation, and their articulating surfaces are ornamented
by pentapetalous striations. There are numerous side-arms sent off
from the column in groups of five, at uncertain distances. The mouth is
situated in the centre of a plated integument spread over the top of
the receptacle. The arms, which arise from the margin of the latter,
surround the mouth, and when spread out, with their numerous pinnæ
or feelers expanded, form a net for the capture of prey; and are the
organs by which the animal obtains food, and conveys it to the mouth.
[Sidenote: FOSSIL CRINOIDEA.]
Fossil Crinoidea.--The fossil crinoids, like the recent prototype above
described, consist of an articulated column, and a receptacle formed of
calcareous plates, and articulated arms or tentacula. They constitute
two groups; the _Encrinites_, in which the ossicula of the column
are subcylindrical and smooth; and the _Pentacrinites_, with a stem
composed of pentangular ossicles, as in the living Pentacrinus.
The petrified remains consist of the ossicula of the column, arms,
and tentacula; of the plates of the receptacle; and of the peduncle,
or process of attachment by which the animal was fixed to the rock.
The peduncle is in some species flat and expanded, like that of the
_Gorgonia_; in others, it consists of long jointed processes. These
several parts are commonly found detached, and intermingled with
detritus in the strata; throughout extensive beds of encrinital marble,
vestiges of the receptacle are but seldom discoverable. In some
localities the skeletons are preserved entire, and lie expanded on the
surface of the layers of shale, clay, or limestone, as if the animals
had been enveloped by the soft deposit when alive in their native seas.
These remarks will serve to convey a general idea of the nature of the
crinoidal remains which are scattered through certain rocks in such
inconceivable quantities; for, much as the columns may differ in form,
the ossicula in their markings, and the plates of the receptacle in
their configuration and ornament, the same general type of structure
prevails throughout the family.
[Illustration: Lign. 90. Stems of Encrinites and Pentacrinites.
Fig. 1.--Screw or Pulley-stone. _Derbyshire._
2, 4.--Articulating surfaces of Encrinital ossicula.
3, 5.--_Entrochites_, or portions of stems of Encrinites.
6, 8, 10.--Portions of Pentacrinital stems.
7, 9.--Articulating surfaces of ossicula of Pentacrinites.
]
Fossil Stems and Ossicula of Crinoidea.--(_Bd._ pl. xlix-lii. _Pict.
Atlas_, pl. xlvii.)--The detached ossicula and stems are so common in
many places, that they attracted the notice of the earlier collectors,
by whom the single pieces were termed _trochites_ (wheel-stones), and
the united series _entrochites_. In the north of England these fossils
are called _Fairy-stones_, and the circular perforated ossicula _Saint
Cuthbert's beads_; the latter were worn as ornaments by the ancient
Britons, and are occasionally found in tumuli.
These petrifactions present considerable variety in form, and in the
markings on their articulating surfaces, which are often radiated and
sculptured in floriform and stellular figures (_Lign. 90, fig. 7,
9_, and _Lign. 91, fig. 3, 4_). The central perforation is small in
some species, and large and pentagonal in others. The ossicula of the
Encrinites often vary in size in the same column, being circular and
elliptical, and thick or thin, alternately, as in the upper part of
the column of the Lily Encrinite, _Lign. 91, fig. 6_; by which great
flexibility and freedom of motion were obtained.
The pentagonal stems also display many modifications; some have five,
others but four sides (_Lign._ 90, _fig._ 6, 8, 10, and 91, _fig._ 7,
9); in some the angles are acute, in others rounded.
Pulley-stones. _Lign. 90, fig. 1._--The circular, or pentagonal
channel formed by the united ossicula of the column, has given rise to
the curious fossils called in Derbyshire the Screw, or Pulley-stones,
which are flint casts of those cavities that occur in the beds of
chert, interstratified with the mountain limestone. The siliceous
matter, when fluid, must have filled up the channel and invested the
stem: the original calcareous ossicles have since been dissolved,
and the casts, now solid cylinders of flint, resembling a pulley,
remain. The masses of chert are often impressed with the ornamented
articulating surfaces of the trochites.
In the quarries on Middleton Moor, near Cromford, Derbyshire, where
extensive beds of limestone composed of crinoideal remains are worked
for chimney-pieces and other ornamental purposes, beautiful examples
of these fossils may be obtained.[267] The cavities of the column and
ossicles are often filled with white calcareous spar, while the ground
of the marble is of a dark reddish brown colour; in other varieties of
the Derbyshire encrinital limestones, the substance of the fossils is
white, and the ground dark grey or brown,[268] A slab of this marble,
with portions of columns lying in relief, and a polished section
showing the inclosed entrochites, are figured _Wond._ p. 650.[269]
[267] See Excursions around Matlock, Part IV. of this work.
[268] Pict. Atlas, pl. xlix. figs. 1, 3, 6.
[269] Upwards of 80 figures of Encrinital remains are given in Pict.
Atlas, pl. xlvii.
[Illustration: Lign. 91. Illustrations of Crinoidea.
Fig. 1.--Group of Living Comatulæ; _nat._ (_Dr. Thompson._)
1_a_.--A single Comatula of the same group, magnified.
2.--Pentremites pyriformis. _Silurian, Ohio._
3, 4.--Surfaces of two pentapetalous ossicula.
5.--A single Ossicle of an Apiocrinus. _Chalk._
6.--Encrinus liliiformis; the receptacle with part of the
column attached; 1/2 _nat._ _From Brunswick._
7.--Pentacrinital stem with four angles.
8.--Entrochite, composed of five smooth ossicles.
9.--Quadrangular stem of seven ossicles.
10.--Cyathocrinus tuberculatus. (_Sil. Syst._)
11.--Receptacle of Bourqueticrinus; _from the Chalk. Lewes._
]
The _receptacle_ which contained the viscera is extremely diversified
in form, and in the number, shape, and arrangement of its plates: the
annexed figure 2, _Lign. 92_, illustrates the several pieces that enter
into its composition. The genera, or sub-genera, are based on the
modifications of shape and structure of the receptacle; and their names
are composed of the termination _crinus_, or _crinites_ (signifying
stone-lily), with a term prefixed expressive of the generic character:
thus we have _Apiocrinus_, or _Apiocrinites_, Pear Encrinite.[270]
[270] The termination _crinus_ is now generally employed, instead of
_crinites_; the latter is preferable, as it indicates the fossil nature
of the specimens. A more expressive name than _Encrinite_ was suggested
by Mr. Martin, of Derbyshire; that of _Stylastritæ_ or Column-Stars.
The receptacle being round and inflated, and composed of pieces
articulated with the stems, and supporting the arms by similar
articulations, are the generic characters of _Apiocrinites_ of
Miller. When round but not inflated--_Encrinus_, when pentagonal,
_Pentacrinus_. When the receptacle is composed of angular plates united
at the edges and forming several series or stages, it constitutes the
basis of the following genera: viz,--
_Platycrinus_; two series, the one of three, the other of five plates.
_Pateriocrinus_; three series each of five plates.
_Cyathocrinus_; three series of five plates, the last with five
intercalated pieces.
_Actinocrinus_; several series of plates: the first composed of three,
the second of five, and the others of many pieces.
_Rhodocrinus_; several series of plates that are covered externally
with radiated ridges. The first course consists of three, the second
of five, the third of ten, and the others of many plates.
_Eugeniacrinus_; of five pieces united into one receptacle.
This brief explanation will enable the student to comprehend the
nature of the almost infinite variety of figure and ornament which the
fossil crinoidea present, and the principles of nomenclature generally
adopted by modern authors. To attempt an enumeration even of the genera
would be inadmissible in these volumes. The late Mr. Miller's "Natural
History of the Crinoidea or Lily-shaped Animals,"[271] will afford the
student satisfactory information on this class of organic remains.[272]
[271] Published in 1 vol. 4to. 1821, with coloured plates.
[272] A beautiful "Monograph on the Recent and Fossil Crinoidea," by
Messrs. Austin, in 4to. is in course of publication, of which but eight
numbers have appeared.
Apiocrinus (_A. Parkinsoni_). _Lign. 92, fig. 4._ (_Wond._. p.
652.)--The Apiocrinite or Pear-Encrinite of Bradford, from its size, and
the abundance of its remains in one particular locality, is the most
generally known of all the British fossil Crinoids. It abounds in the
beds of oolite, in the quarries on the heights above the picturesquely
situated town of Bradford, in Wiltshire. The receptacle, detached
ossicula, and the pedicle, are very common; and in some instances the
entire endo-skeleton, from the peduncle to the extremities of the arms,
is preserved. The late Channing Pearce, Esq., of Bradford, by unremitting
attention to the collection of these fossils, obtained the beautiful
specimens deposited in the British Museum.[273]
[273] Petrifactions, Room II. Wall-case G.
This Apiocrinite has a smooth receptacle of a pyriform shape, composed
of large thin plates with radiated articulating surfaces; the stem
is short and strong; the arms are simple, resembling those of the
_Marsupite_; the peduncle spreads out into an expanded base, which
is firmly attached to the rock, like that of the Gorgonia, and is
generally of a rich purple colour.[274]
[274] Pictorial Atlas, pl. xlix. Pulley-stones and Encrinital marbles;
pl. 1. Apiocrinites.
[Illustration: Lign. 92. Fossil Crinoidea.
Fig. 1.--Eugeniacrinus. _Switzerland._
2.--Cyathocrinus planus. _Mountain Limestone._
_a._ Basal plate of the _receptacle_.
_b._ One of the plates composing the walls of the pelvis.
_c._ Costal plate.
_d._ Intercostal plate.
_e._ Scapula, or ossicle that receives the arm.
_f._ First ossicle of the arm.
3.--Marsupites Milleri (G. A. M.). _Chalk, Brighton._
_a._ The semilunar cavity for an attachment of the arm.
4.--Apiocrinus rotundus, _Pear-Encrinite. Bradford._
_a._ First ossicles of the arms.
]
Sir Charles Lyell mentions an interesting fact relating to the
occurrence of these fossils in the Oolitic limestone at Bradford. In
Burfield quarry, on the heights that overlook the town, a bed of
limestone was exposed, the upper surface of which was incrusted with
the stony peduncles or roots of Apiocrinites; upon this stratum was
a layer of clay, in which were innumerable remains of receptacles
and ossicula of stems and arms; some of the stems were erect, others
prostrate, and throughout the clay were the dismembered remains. This
submarine forest of Crinoideans must therefore have flourished in
the clear sea-water, till invaded by a current loaded with mud that
overwhelmed the living zoophytes, and entombed them in the argillaceous
deposit in which their fossil remains are imbedded.[275]
[275] Burfield quarry, on the heights of Bradford, is the locality
referred to; but I believe it is rarely that any specimens of the
Apiocrinite are to be found in an erect position. I could not learn
from any of the local collectors, that an example had been seen by
them. When I visited the quarry in June, 1848, no good section of the
beds was apparent: a few detached plates of Apiocrinites were the only
relics we could meet with. Mr. Reginald Mantell, when engaged on the
construction of the railway near Bradford, sought repeatedly, but in
vain, to discover any Apiocrinites in an erect position, or as if lying
on the spot where they grew.
The constituent substance of the ossicula and plates of the Bradford
Encrinite is calcareous, and has an oblique fracture; the colour is
generally a light ochre, or a bluish grey.[276]
[276] Pict. Atlas, pl. 1. contains figures of the Bradford Encrinites.
[Sidenote: APIOCRINITE OF THE CHALK.]
Apiocrinus ellipticus. _Lign. 93._--Detached ossicula of this small
encrinite are abundant in the White Chalk; the receptacle is known
to the quarrymen by the name of "_bottle_." The pieces composing the
column are cylindrical in the upper part, and elliptical and angular
in the lower, and are articulated by a transversely-grooved surface.
The two upper joints are enlarged, and support the receptacle, which is
smooth and round (_fig._ 1). The column has articulated side-arms, and
the base numerous jointed processes of attachment, which, when found
apart from the column, have been mistaken for a distinct type, and
named "_Stag's-horn Encriniter_."[277] The specimens figured _Lign.
93_, show the essential characters of this crinoid; when perfect, this
species must have borne a general resemblance to the Pear Encrinite of
Bradford.
[277] Pict. Atlas, pl. xlvii. _fig._ 31, p. 113. In the same plate there
are figures of several specimens of detached portions of the stem of
this species from the Kentish Chalk.
[Illustration: Lign. 93. Apiocrinites. _Chalk, Lewes._
Fig. 1.--Apiocrinus ellipticus, × 3.
1_a_.--Part of the elliptical portion of the column, with a
side-arm.
1_b_.--Portion of the same, magnified.
1_c_.--The articulating surface of an ossicle.
2.--Ossicle of A. flexuosus. (_M. D'Orbigny._).
3.--Portion of the cylindrical stem.
]
Bourqueticrinus (D'Orbigny). _Lign. 91, fig. 11._--Detached ossicles
of other species belonging to the same genus, or to allied genera,
are frequently met with in the Kentish and Sussex chalk. A common
form is that figured in _Lign. 91_, which is part of the receptacle
of a crinoid, named as above; it differs from the other Apiocrinites
of the chalk in the articulating surfaces of the ossicles not being
radiated, and in the receptacle, which is small and pyriform, not
having a distinct cavity; there is only a median canal, which is seen
in a vertical section: but the entire structure of the summit does not
appear to be shown in any specimens hitherto observed.
Encrinus liliiformis (_Lily Encrinite_). _Lign. 91, fig. 6._--This
exquisite Crinoid is equally interesting and attractive to the amateur
collector and the naturalist. Its remains do not occur in the British
strata, and are only known in the muschelkalk of Lower Saxony. The
specimens in this country are chiefly from Erkerode, in Brunswick;
they are found in a layer, about eighteen inches thick, of a soft
argillaceous cream-coloured limestone, chiefly made up of trochites,
detached ossicula, and a few fragile shells and corals.
The receptacle of the Lily Encrinite is smooth, and in the form of a
depressed vase; its base is composed of five plates, upon which are
placed three successive series of other plates, with the uppermost of
which the arms articulate. The stem is formed of numerous perforated
round ossicles, articulated to each other by radiated grooved surfaces,
and becoming somewhat pentangular, and alternately larger and smaller,
towards the summit, to which the receptacle is fixed; a construction
admitting great freedom of motion.[278]
[278] Mr. Miller's work should be consulted for details of structure.
This Encrinite when lying in relief on the rock, with its receptacle
entirely or partially closed (see _Wond._ p. 548), so strikingly
resembles the bud or expanding flower of a Lily or Tulip, as to justify
the popular name of Stone-lily. An exquisite specimen is figured by Mr.
Parkinson;[279] the British Museum possesses some fine examples.[280]
[279] Pict. Atlas, pl. xlviii.
[280] Petrifactions, p. 77.
Mr. Parkinson detected the animal membrane in ossicles of this crinoid,
by immersing them in dilute hydrochloric acid.[281] My friend Mr.
Frederick Harford has repeated the experiment with success.
[281] See Pict. Atlas, pl. xlvii. _fig._ 47.
[Sidenote: PENTACRINITES.]
Pentacrinites.--The description of the recent _Pentacrinus_
_caput-medusæ_ (_ante_, p. 282), illustrates the characters of the
crinoideans whose fossil remains are so familiar to the palæontologist,
under the name of Pentacrinites. In these animals the pieces composing
the receptacle are firmly articulated together; the rays of the disk
are fixed immediately to the summit of the column by special ossicula;
and the stem is composed of angular pieces, which are generally
pentagonal. The receptacle is small, and situated deep between the
bases of the arms; it is closed above by an integument covered by
minute plates or flat ossicles (_Lign. 94, fig. 2_). The fossil
remains of several species are abundant in the Lias and Oolite of
Dorsetshire, Somersetshire, &c. Slabs of limestone may be extracted
with the surface covered with these crinoideans, spread out as if
floating in their native element; very commonly they are transmuted
into sulphuret of iron, or have a coating of brilliant pyrites.[282] The
neighbourhoods of Lyme Regis, and Charmouth, are celebrated for these
organic remains. A small specimen of the arms of a pentacrinite on Lias
shale is figured in _Lign. 94, fig. 3._
[282] Pictorial Atlas, pl. li. lii.
The arms in many of the plumose pentacrinites are very long and thickly
beset with side-arms, and minute pinnæ, all of which are composed of
separate articulated ossicles, so that the number of bones in a single
endo-skeleton of those crinoids amounts to from fifty to one hundred
and fifty thousand distinct pieces. The Briarean Pentacrinite,[283] so
named from its numerous tentacula, is literally a tuft of articulated
processes, appearing like a delicate fibrous plume attached to a
stem. The _Pentacrinus Hiemeri_ is a beautiful example of this type
of crinoids, of which there is a noble group, comprising upwards of
thirty individuals, on a slab in the British Museum,[284] exposed on
the surface of the stone in as perfect a state as if just dredged up
from the bottom of the sea. The pentacrinites are for the most part
entire; the peduncle being fixed, and the column extending upwards
in gentle undulations, and supporting the receptacle, from which the
arms are gracefully outspread in various attitudes. The structure of
the receptacle, and of the arms, and the extreme delicacy of the finer
tentacula made up of countless minute ossicula, are admirably shown in
this unique and most instructive fossil.
[283] Pictorial Atlas, pl. xlvii. The Briarean Pentacrinite is fully
illustrated and described in detail in Dr. Buckland's Bridge water
Essay, p. 484.
[284] This species was named and figured by M. König in his "_Icones
Fossilium sectiles_," pl. iii. _fig._ 29, in 1826. See Petrifactions,
p. 88.
[Illustration: Lign. 94. Actinocrinites, or Nave Encrinites.
Fig. 1.--Actinocrinus Parkinsoni. (_Org. Rem._ ii. pl. xvii. _Pict.
Atlas_, pl. li.)
2.--Section of an Actinocrinus, (_Miller's Crinoideæ_, pl. ii.)
a. Proboscideal protrusion of the plate and integument.
b. Sections of the folded or closed arms.
3.--Arms of a Pentacrinite, on Lias-shale; _Lyme Regis_.
]
[Sidenote: ACTINOCRINUS. CYATHOCRINUS.]
Actinocrinus (_Nave Encrinite_). _Lign. 94, fig. 1, 2._ (_Wond._
p. 585. _Bd._ pl. xlvii.)--The column is formed of numerous round
ossicula, possesses side-arms, and is fixed by root-like processes.
The receptacle is of an irregular subspherical form, the arms passing
off at right angles like the spokes from the nave of a wheel; hence
the name. The base is composed of three plates which support five
hexagonals and one pentagonal, and on these are three other series;
from the upper margin of the last, five arms are given off. The
receptacle is closed by a dome-shaped tesselated covering (_Lign. 94,
fig. 2_), having on one side the opening for the mouth and vent. The
specimen, _fig. 1_, is a receptacle without a stem, and with but a few
joints of the arms; this is the usual state in which these fossils are
obtained. _Fig. 2_ is an _Actinocrinite_ in which part of the brim of
the receptacle and of the arms has been removed in front, leaving a
portion of the coalesced arms partially surrounding the proboscideal
plated integument that covers the upper part of the receptacle; the
figure is from Mr. Miller's work, and is introduced to illustrate the
structure of these crinoideans.[285]
[285] Miller's Crinoidea, _fig._ N. pp. 98-100.
The external surface of the plates of the receptacle in the
Actinocrinites, is generally covered with radiated markings and
ridges, so that detached plates have been mistaken for those of
Marsupites; see the restored figure of a Nave Encrinite, _Wond._ p.
654. In some species the receptacle is richly ornamented; but in the
specimen figured, _Lign. 94, fig. 1_, the surface has been defaced in
consequence of the fossil having been immersed in strong acid.
Cyathocrinus (_Cup-like Encrinite_). _Lign. 95_, and _Lign. 92, fig.
2_.--The column is formed of round, depressed, perforated joints,
articulating by radiated surfaces; pentagonal near the summit. The
receptacle is composed of five pieces, succeeded by two successive
series of five plates, with intervening plates, and supports five
bifurcating, radiated arms.
[Illustration: Lign. 95. Cyathocrinites planus; _nat._
_Mountain Limestone, Clevedon._]
The Encrinites of this genus have a light and elegant appearance: the
forms of the plates composing the pelvis, and of the ossicula of the
arms, are shown in _Lign. 92, fig. 2_; which represents a specimen of
_C. planus_, from the magnesian limestone of Somersetshire; a beautiful
example of the same species is figured in _Lign. 95_. The receptacle
resembles in shape a depressed vase; its upper part was probably
covered by a plated integument, having an aperture in the centre as in
the Actinocrinites. Cyathocrinites occur in the Silurian, Devonian, and
Carboniferous formations.[286]
[286] A figure of Cyathocrinus rugosus is given in Pict. Atlas, pl.
xlix. _fig._ 4. The same work contains coloured figures of Pentacrinus
scalaris (Goldfuss), pl. xlvii. figs. 57, 64, 66; Pentacrinus
basaltiformis, pl. xlvii. _fig._ 47.
A remarkable receptacle, with the tentacula partially introverted, is
figured Pict. Atlas, pl. xlvi. _fig._ 2, from Gloucestershire; and
several beautiful examples of the arms, tentacula, &c. of Pentacrinites
in Lias limestone and shale, in pl. li. figs. 9, 15, 16, and pl. lii.
figs. 1, 2, 3, from Charmouth.
Rhodocrinus. (_R. verus._ _Pict. Atlas_, pl. xlix. _fig._ 7, 8.)--A
beautiful form, allied to the Antinocrinoids, occurs in the palæozoic
rocks, and is named the Rose-encrinite by Miller. The column is
cylindrical and traversed by a pentagonal canal. The rays or arms
arise by a single ossicle and then bifurcate: the receptacle is
formed of three, five, ten, and more numerous series of plates, which
are ornamented externally. A fine example of a crinoid of this type
(_Hypanthocrinus_) from the Wenlock limestone, is figured in the London
Palæontological Journal, pl. xxi.
In Sir R. Murchison's Sil. Syst. all the crinoids of the Silurian
deposits, then known, are figured. Several new genera are described by
Professor McCoy, in the Synopsis of British Palæozoic Fossils.
Eugeniacrinus (_Clove-like Encrinite_). _Lign. 92, fig. 1._--These
little crinoids, which resemble a clove in form, are found at Mount
Randen, in Switzerland, in Oolitic limestone. The receptacle is simple
in structure, for it has but one series of plates; its cavity is very
small. It had five arms: the articulating surface of the ossicles is
radiated. When perfect this crinoidean must have somewhat resembled the
Lily Encrinite, but the plates are all anchylosed, or blended together,
which Mr. Miller attributed to an early stage of growth.
[Sidenote: PENTREMITES PYRIFORMIS.]
Pentremites pyriformis (_Pear-shaped angular Encrinite_). _Lign.
91, fig. 2._--The column of this remarkable crinoid is short, and
formed of cylindrical, perforated ossicula, with radiated surfaces,
and has irregular side-arms. The receptacle is composed of polygonal
plates, divided by five perforated grooves or furrows, which are of
an elongated petalous form, and converge in a rosette on the summit.
The marginal longitudinal rows of minute pores are not however for the
passage of soft membranous feelers, as in the ambulacra of echinoderms,
as was formerly conjectured, but are channels for the transit of
vessels that supply an infinite number of delicate simple tentacula,
composed of extremely minute calcareous ossicula, as in the other
Crinoidea, but not subdivided as in the Pentacrinites and Encrinites.
These articulated tentacula are arranged close together in longitudinal
rows on the ambulacral spaces; there being two rows, each consisting
of fifty tentacula, on every space. They are directed upwards towards
the vertex of the receptacle, and appear to be the instruments for the
capture and conveyance of food to the mouth.[287]
[287] See Dr. Fred. Röemer on jointed tentacles found on the ambulacral
spaces of _Pentremites_, "Geol. Journal," vol. v. p. 8.
There are several species of Pentremites, some of which swarm in the
cherty limestones of Kentucky. Mr. Say, to whom we are indebted for the
first satisfactory investigation of these fossils, mentions that such
is their abundance, that he has observed, on a piece of rock not larger
than three inches by two-and-a-half, above twenty specimens lying in
relief
Cystidea.--In the ancient fossiliferous strata there occurs a
remarkable family of crinoideans, which is supposed to be restricted
to the palæozoic ages; these fossils have been named by Von Buch,
_Cystideæ_, from the body of the animal being wholly inclosed in a
cyst, or box. The receptacle is of a spherical form, and composed of
polygonal plates, articulated to each other; it has distinct apertures
for the mouth, vent, and oviduct; the orifice of the latter is closed
by valves. It has a short pedicle, but no arms have been discovered,
and the Cystideæ are generally described as Crinoids without appendages
of this kind. But in some members of this group, there are not only
arms and tentacula, but likewise certain organs connected with the
plates, which Prof E. Forbes terms, "pectinated rhombs," the functions
of which are not obvious. The arms more closely resemble those of
the Ophiuridæ than of the Crinoidea.[288] This order comprises several
genera, and is the type under which the Crinoidea first appear in
the natural records of our planet, according to the present state of
our knowledge, and which becomes extinct before the advent of the
Pentacrinites.
[288] See a memoir on the British Cystidea, by Prof. Ed. Forbes; in the
Mem. Geological Survey, vol. ii.
[Sidenote: MARSUPITES MILLERI.]
Marsupites Milleri. _Lign. 92, fig. 3, Lign. 96._ (_Wond._ p.
652.)--The fossil remains of a genus related to the Encrinites, but
separated from them by being unattached and free, having no column
of support, were first described by the late Mr. Parkinson under the
name of "_Tortoise Encrinite_" (_Org. Rem._ vol. ii. pl. xiii. _fig._
24, _Pict. Atlas_, pl. xlvii.); but misled by the resemblance of some
of the plates to those of certain species of Actinocrinites, Mr.
Parkinson supposed the original to have possessed a jointed column. The
examination of specimens obtained from the Chalk of Lewes and Brighton,
enabled me to determine the true characters of the original; the
purse-like form when the arms are closed suggested the name Marsupites
(_purse-like_), by which it is now generally known; the specific name
_Milleri_, is in commemoration of the late excellent and able author of
the Natural History of the Crinoidea.
The receptacle of the Marsupite is of a sub-ovate shape, and rounded
and entire at the dorsal extremity; a large central plate forms
its base, on which is placed a successive series of pentagonal and
hexagonal plates, the margins of which are in contact, but not
anchylosed nor firmly united; to the periphery of this cup are
articulated five arms, which subdivide into ten rays, or tentacula. The
top of the receptacle was closed by an integument, covered by numerous
small semilunar plates, in the centre of which was situated the oral
aperture. The external surfaces of the plates of the receptacle are
generally granulated and radiated, as in _Lign. 92, fig. 3_; but in
some specimens the surface is quite smooth, a character which possibly
may be specific. Some examples have the surface granulated and rugous,
and these Mr. Miller regarded as distinct, and named _M. ornatus_. I
have not of late years been able to obtain specimens to determine this
question.
The Marsupites vary in size, from an inch to three inches in length,
exclusive of the arms. The receptacle is relatively very capacious
compared with that of other crinoideans. The central plate is large,
and of a pentagonal form, without the slightest indication of any
column or process of attachment: five pentagonal plates are united
to the sides of the basal plate, and above these a like number of
hexagonals, which receive the five upper plates that constitute the
margin; these have each a semilunar depression, to articulate with the
first bones of the arms, or brachial appendages.
[Illustration: Lign. 96.--Marsupites Milleri, _nat._
_Chalk, Lewes._]
Detached plates and ossicula of marsupites are not uncommon in the
Chalk of Kent and Sussex; nearly entire receptacles, filled with chalk
or flint, are occasionally found in the pits near Lewes and Brighton;
but examples with remains of the arms are extremely rare; and I have
seen but one specimen (which I collected from the Sussex chalk), in
which the plates of the integument that covered the opening of the
receptacle are preserved.[289]
[289] It is figured in my _South D. Foss._ pl. xvi. _fig._ 6.
The Marsupite is an exceedingly interesting type, in a zoological
point of view, since it forms a link that unites the Crinoidea with
the Comatulæ, or feather-stars, which we shall presently notice. Its
general form and habits are sufficiently indicated by the numerous
specimens that have been collected in the Chalk of the south-east of
England.
The body of the animal was inclosed in a crustaceous case formed
of large plates, articulated to each other by suture; the mouth or
oral aperture was situated in the centre of the plated integumental
cover of the receptacle. The organs of locomotion and prehension
consisted of five arms or brachial appendages, formed of ossicula
as in the crinoidea, and the whole was invested with soft tissue or
integuments. When floating in the water, the creature could spread
out its tentacula, and form a net to capture its prey, and by closing
them, secure it, and convey it to its mouth. The figure, _Lign. 96_,
is restored from specimens which separately exhibit the parts here
represented in connexion.
* * * * *
Fossil Asteriadæ.
[Sidenote: FOSSIL ASTERIADÆ.]
The radiated animals, popularly called _Star-fishes_, from their
stellular forms, are so abundant on our coasts, that the common
five-rayed species must be familiar to all my readers who indulge
in rambles on the sea-shore, and will serve as an illustration of
the general appearance and structure of the beings whose petrified
remains now claim our attention. This species belongs to the division
of Asteriadæ, in which the rays are elongated, and far exceed in
length the diameter of the disk; in another group (_Goniastea_, or
Cushion-star), the body is angular, and the lobes or rays are short,
and not longer than the diameter; while in a third subdivision
(_Comatula_ and _Ophiura_), the arms are distinct from the body, and
articulated, elongated, and ramified, as in the _Crinoidea_.
The external surface of the common Star-fish is soft, and attached to
a tough coriaceous integument, investing a skeleton composed of an
infinite number of calcareous ossicula, arranged in regular series
along the margins of the rays. Each ray has a longitudinal furrow,
perforated at the sides by alternating rows of pores, through which
tubular tentacula are protruded. The mouth is situated in the centre
of the under surface. Now if we imagine a Star-fish placed with
its mouth upwards, and the five rays fringed with long articulated
tentacula, as in the Comatula, and fixed by the centre of its dorsal
surface upon a jointed stem, we shall have the essential characters
of a crinoidean; and the animals of one recent tribe of _Asteriadæ_
are actually in this condition in the earlier stage of their
existence: these are the _Comatulæ_, or Feather-stars, in some of
which (the _Euryale_), the arms are as numerously subdivided as in the
Pentacrinites.[290]
[290] The reader interested in this subject should peruse the charming
volume on British Star-fishes and other Echinoderms, by Professor
Edward Forbes. 1 vol. 8vo. John Van Voorst. 1841.
From the importance of the Crinoidea in the economy of the ancient
world, the history of the only type at present inhabiting Europe, the
ancient seas of which swarmed with numerous forms of these beautiful
creatures, presents many points of interest. The receptacle of the
soft body of the _Comatula_, like that of the Crinoideans, consists
of a cup-shaped calcareous base, which sends off from its margin five
arms, that quickly subdivide, and are beset on each side with rows of
articulated pinnæ; on the convexity there are also numerous slender,
jointed, simple, tentacula. The mouth is situated in the centre of
the area surrounded by the arms, and is capable of being elongated
into a proboscis. In the young state, the Comatulæ are attached by a
jointed stem to other bodies, as shown in _Lign. 91, _fig. 1_, which
represents several of the natural size; _fig. 1a_ is an enlarged
view of an individual, and closely resembles an expanded Crinoidean.
The stem is composed of about eighteen joints, which are pentangular;
after a few weeks the Feather-star becomes detached from its peduncle,
and ranges the sea in freedom.[291]
[291] The researches of J. V. Thompson, Esq. first brought to light
these interesting facts in the Natural History of the Comatula; this
eminent naturalist first observed pedunculated Comatulæ in the Cove of
Cork. When this discovery was first made known to me, I suspected that
the _Marsupite_ might have been pedunculated when young; but as very
small specimens of this Crinoid are equally free from all traces of
a stem as the adult, I was led to relinquish that opinion: still the
collector, when searching for Crinoidean remains, should bear in mind
the possibility of this having been the case.
In the Comatulidæ, the arms are distinct from the body; these animals
therefore closely approach the Crinoideans: in the true Star-fish,
the angular processes, or arms, are an integral part of the body,
containing a portion of the stomach, ova, &c., and are furnished with
rows of pseudopodia.
Fossil Comatulæ have been discovered in the Solenhofen slate; and it is
not improbable that some of the numerous Crinoideans may be Asteriadæ
in the early stages of development.
In another group, Asteriadæ, (named _Ophiuræ_ or Serpent-stars,) the
rays are long and slender, and without grooves or tentacula, and are
distinct from the body. These organs are extremely flexuous, and in
some species beset with spines, and enable the animal to seize and
entwine round its prey. The mouth is central, and there is an ovarian
aperture at the base of each of the five arms.
Though the fossil Star-fishes comprise many extinct genera, they
belong to the same families as the recent; and Comatulæ, Ophiuræ,
and Asteriadæ, occur in the Lias, Oolite, and Chalk, in considerable
numbers. Professor Edward Forbes has determined many of the British
species, and it is to be hoped, will publish a monograph on the
Fossil Asteriadæ, as a companion to his delightful work on the recent
Star-fishes.
[Sidenote: FOSSIL OSSICULA OF STAR-FISHES.]
Fossil Ossicula of Star-fishes.--From the immense number of little
bones which enter into the composition of the skeleton of a single
Star-fish, and which are but slightly held together after the death of
the animal and the decomposition of the soft parts, we can understand
how layer upon layer of ossicula of Asteriadæ may have been formed at
the bottom of the cretaceous seas; as we find them in the quarries near
Arundel, Worthing, &c. Whoever has witnessed the hauling up of the
dredge off our coasts, and seen the mass of living Star-fishes which it
brings up, as if the sea-bottom were a living bank of these Radiata,
will not be surprised at the vast quantities of their fossil remains.
This profusion of the living animals of this family, serves also to
account for the enormous amount of those kindred but extinct forms,
whose relics were the subject of investigation in the former part of
the present chapter.
The ossicula vary in shape in different parts of the skeleton, and
Prof. E. Forbes affirms, that the careful determination of their
characters is of great importance, since they are the only paints of
the animals likely to be preserved, and the shape of an ossicle is as
truly indicative of a genus or species, as is that of a bone among the
vertebrata. There is one ossicle situated on the side of the centre of
the disk, which is worthy of remark, because it often occurs in the
chalk mingled with the debris of the rest of the skeleton, and should
be preserved by the collector. It differs from all the other bones in
being marked with radiating grooves, and is called the madreporiform
tubercle; it appears to be the analogue of the stem of the Crinoideæ,
in other words, a rudimental condition of an organ, which is fully
developed in that order of radiata.
[Sidenote: OPHIURA.]
Ophiura. _Lign. 97, fig. 1._--Several species of this genus, which is
distinguished by the long, slender, serpent-like arms, and the circular
disk covered with plates and spines, have been found in a fossil state:
one species was discovered in the Lower Silurian deposits by Prof.
Sedgwick, and other forms have been obtained from all the succeeding
formations. The Lias near Lyme Regis and Charmouth has yielded many
beautiful examples of _Ophiura Egertoni_. Professor John Phillips has
figured a species (_Oph. Milleri_, Geol. York, pl. xiii.) from the
marlstone of Yorkshire, and a species from the Oxford Clay has been
described as _Ophiura Prattii_. In the Cretaceous formation, remains
of several species have been found. The first specimen from the Sussex
Chalk that came under my notice, was discovered many years since, by
my son, in a quarry at Preston, near Brighton; the rays were admirably
preserved, as shown in the portion figured in _Lign. 97._ An example
of this species, with the disk entire, and portions of five arms, was
found by Henry Catt, Esq. and is represented in pl. xxiii. _fig._ 2, of
Mr. Dixon's work.[KF]
[292] Three plates are devoted to the Cretaceous Star-fishes: the
descriptions by Prof. E. Forbes comprise twenty-five species, belonging
to the genera Oreaster, Goniaster, Stellaster, Arthraster, and Ophiura,
all from the Chalk of Sussex and Kent.
[Illustration: Lign. 97. Fossil remains of Star-fishes.
Fig. 1_a_.--Part of the ray of Ophiura serrata; _nat._ _Chalk, Preston._
(_Mr. Walter Mantell._)
1.--Portion of the same magnified.
2.--Goniaster Hunteri. _Chalk. Gravesend._
]
[Sidenote: GONIASTER--ASTERIAS.]
Goniaster. _Lign._ 97 and 98.--The star-fishes of this genus, popularly
called Cushion-stars, are of a pentagonal form, and have a double
series of large marginal plates, bearing granules or spines; the latter
are seldom preserved in the fossils. The upper surface is nodulose.
[Illustration: Lign. 98. Fossil Star-fish. _Chalk, Kent._ Goniaster
Mantelli. (_sp Forbes._[293])]
[293] Dixon's Cret. Foss. p. 332.
The detached ossicula of the skeletons of Cushion-stars are frequent
in the White Chalk; and the large central bone, the _madreporiform
tubercle_, which is present in the dorsal aspect of all star-fishes,
is large, and therefore often observed, and may be easily mistaken for
the base of a crinoidean receptacle. The layers in the Sussex Chalk
composed of the exuviæ of star-fishes, as previously mentioned, are
chiefly made up of ossicula of goniasters.
There are two species not uncommon in the Chalk, of which portions may
generally be obtained from the pits near Gravesend; and occasionally
very fine examples of the entire goniaster are met with. Mr. Dixon's
work contains figures of several exquisite fossils of this kind. These
organic remains were familiar to the early collectors: Mr. Parkinson
figures several in Org. Rem. vol. iii. pl. i. and ii.[294]
[294] Pict. Atlas, pl. liii.
_Goniaster Hunteri_ (_Lign. 97_), has the body obtusely pentagonal, and
the sides nearly straight; the superior intermediate marginal plates
are four, equal, broadly oblong, coarsely mamillato-punctate; the
ossicula of the disk hexagonal.[295] This species is common in the upper
chalk.
[295] Prof. Forbes, Dixon's Cret. Foss. p. 331.
In _Goniaster Mantelli_, _Lign. 98_, the body is pentagonal, but the
sides are curved, with projecting angles; the ossicula of the disk
are punctated. The superior intermediate marginal plates are oblong,
narrow, punctate, marginate, and six in number.[296]
[296] Ibid. p. 332.
Specimens of these Goniasters are sometimes met with attached to a
nodule of flint, in an extraordinary state of freshness; sharp imprints
of the external surface, the skeleton having perished, are also found
in flints, and, rarely, casts in pyrites. The whetstone of Dorsetshire
often bears distinct moulds of Goniasters! I have found ossicula of
this form of Star-fish in the London Clay of the Isle of Sheppey.
Asterias. _Lign. 99._--The animals of this genus, of which the common
Star-fish is the type, are stellate in form; the rays are flat, and
extend from the body, of which they are a prolongation--not mere
appendages. They have deep grooves or furrows bordered by marginal
plates, which are continued to the extremities.
The Lias of Germany has yielded several species of Asterias; one of
which is figured, _Lign. 99_. A very large species occurs in the
Cornbrash of the Oolite of England. A magnificent specimen of _Asterias
arenicola_ (Goldfuss), from the calcareous grit, near Pickering,
Yorkshire, measuring 10-1/2 inches from the extremity of one ray to
that of another, is figured in the London Palæontological Journal, pl.
xvii. The same work contains admirable figures of _Ophiura Egertoni_,
and _Oph. senatu_ in flint, pl. xix.; _Oph. Milleri_ in Staithes
marlstone, and _Oph. Murravii_, pl. xx.; and two specimens of _Oph.
Milleri_ on the same slab of Lias from Staithes, near Whitby, pl. viii.
The Star-fishes of the British palæozoic strata are described by Prof.
E. Forbes in the Memoirs of the Geol. Survey, _Decad._ 1.[297]
[297] See also Prof. M'Coy's Lower Palæozoic Fossils, p. 58.
[Illustration: Lign. 99. Fossil Star-fish. _Lias, Wirtemberg._
Asterias prisca. (_Goldfuss._)]
[Sidenote: GEOLOGICAL DISTRIBUTION OF CRINOIDEA.]
Geological distribution of the Crinoidea.--The great number of extinct
forms of this order of Radiata in the most ancient fossiliferous
deposits, is a remarkable fact, which has already been incidentally
adverted to. In the palæozoic seas--including the Silurian, Devonian,
Carboniferous, and Permian--the Crinoidea were represented by upwards
of fifty genera, whose existence began and ended during that geological
cycle.
According to the present state of our knowledge all those peculiar
types of radiated animals were created, and each lived through the
destined period alloted to its race, and died out ere the deposition
of the New Red Sandstone; not a single species, not a relic of the
innumerable individuals that swarmed in the palæozoic oceans, has been
observed in any strata above the Permian.
The Trias, which ranks as the earliest of the secondary formations, is
characterized by the advent of two typical genera; the true Encrinus or
Lily-encrinite, and the Pentacrinus; the former is unknown in any other
deposits; the duration of its race was comprised within the Triassic
epoch. The Pentacrinus, on the other hand, has been perpetuated through
all the succeeding periods, and one species inhabits the present seas;
the sole existing representative of the most ancient type of this order.
In the Oolite, another living form, the Comatula, first appears.
The ocean of the Cretaceous epoch was inhabited by five genera of
Crinoids, unknown elsewhere; among them is that remarkable genus, the
Marsupite.
The Crinoidea of the Tertiary seas are as few in number and variety as
those of the present day; not a vestige of any of the ancient tribes
has been discovered. M. D'Orbigny's _Tab._ 12 presents the phenomena
thus briefly noticed, in a striking point of view.
* * * * *
From this review of the fossil Crinoidea and Asteriadæ, the student
will be in some measure prepared for the collecting of instructive
specimens from the immense accumulation of remains imbedded in certain
strata of the Oolitic, Liassic, Carboniferous and Silurian rocks.
The British species of fossil Crinoidea amount to more than two
hundred, and when the great number of bones that enter into the
composition of the skeleton of a single Pentacrinite or Encrinite is
considered, the prodigious quantity of the fossil remains of these
zoophytes in the ancient deposits may be readily conceived. Polished
slices of the encrinital marbles of Derbyshire, and of the Lias
limestones from Lyme Regis and Charmouth, should be obtained, as they
show sections of the imbedded crinoidal stems and detached ossicula;
and sometimes of the receptacles.
CHAPTER IX.
FOSSIL ECHINIDÆ, OR SEA-URCHINS.
[Illustration: Lign. 100. Turban Echinus, with its spines; 1/2 _nat._
(_Hemicidaris crenularis, Agassiz._)
_Jura limestone._]
The fossils we have now to examine are among the most familiar of the
objects commonly known as petrifactions; for as the enveloping cases
of the Echini possess considerable durability, they have served as
moulds into which silex, calc-spar, limestone, pyrites, and other
mineral substances, when in solution, or in a semi-fluid state, have
percolated, and formed sharp and enduring casts, which exhibit the
forms of the plates, and the disposition of the pores, striæ, &c. of
the original structures.
The common Echinus of our sea-coasts (_Echinus sphæra_), known by the
name of Sea-egg, Sea-urchin, or Sea-hedgehog, presents the typical
characters of this order of Radiata, which differs from the Crinoids
and Star-fishes in the absence of arms.
The calcareous envelope of the Echinus, or shell, as it is popularly
called, is composed of many calcareous, polygonal plates, closely
fitted to each other, and arranged in regular and elegant patterns;
appearing in the globular and spherical kinds like the lines of the
meridian on a globe. The plates are disposed in ten vertical series,
united by serrated sutures, and form sections, into which the envelope
or case very commonly separates upon the decay of the investing
integuments. Of the ten bands five are large and five small. The large
bands (_areæ_) are each composed of a double row of plates, ornamented
with tubercles supporting large spines (_Lign. 100_). The five narrower
bands consist of much smaller plates, and the spines are minute, or
altogether wanting; hence these bands appear like avenues through the
spinous tracks, and have therefore been fancifully termed ambulacra
or walks. They are the equivalents of the grooves or furrows of the
Star-fishes (_Lign. 108, a_.); and are traversed by numerous pores,
for the exsertion of tubular feet, or tentacula. Besides these rows
of minute openings, there are two principal apertures, the mouth and
the outlet or vent; and also a few large pores, commonly five, on the
summit, for the exclusion of the ova, and the free admission of water.
The form and relative position of the parts above described, afford
characters by which the order is divided into genera. The mouth, which
is situated on the lower part, is in some species furnished with five
sharp angular teeth, attached to a calcareous framework that admits
of being protruded; this apparatus, when entire, commonly bears the
name of "_Diogenes' lantern_." The eminences on the surface of the
plates vary in size from mere granules, or papillæ, to large mamillated
tubercles; they serve for the attachment of movable spines, which also
present great variety of form and ornament. The spines have a cup-like
cavity at the base which fits on the papillæ, and in many species are
only supported by the capsular envelopment of the common integument;
but in others, the large spines are attached by a ligament which passes
from the centre of the socket, and is received in a perforation of the
papilla of each tubercle, in the same manner as the _ligamentum teres_
of the human thigh-bone. Transverse slices of the spines exhibit the
internal structure, and are beautiful objects under the microscope.
There are also minute appendages to the integument, called
_pedicellariæ_, or pinchers, of a very remarkable character, whose
functions are not known. They are slender columnar bodies, each crowned
with three calcareous teeth-like spines, beautifully sculptured, and
which in some species are long and slender, in others short and obtuse.
I have not observed any traces of these bodies, even in the best
preserved echinites, but as they are as durable as the spines and case,
they may exist in a fossil state.
[Sidenote: TURBAN ECHINITES.]
This general view of the structure of the recent Echinites will enable
the student to understand the nature of the fossil remains; for the
parts above described, are found more or less perfectly preserved,
either in their natural arrangement, or separated and dispersed in
the rock. The habits of these animals, of burrowing in the sand, were
favourable to their preservation in a mineralized state; and in some
of the oolitic limestones, hundreds of beautiful examples of Turban
Echinites (_Cidares_), having their spines spread out on the face of
the rock, are found lying in the positions they evidently occupied
when living. The quarries near Calne and Chippenham, in Wilts, are
celebrated for such fossils.
It was my intention to give figures of the genera into which the
numerous fossil species have been divided by modern authors: but
I found the attempt hopeless, from the changes in nomenclature and
arrangement which are constantly taking place. The monographs on the
fossil Echinidæ, by Prof. E. Forbes, now in course of publication by
the Government School of Mines, will, when completed, place this branch
of Palæontology on a satisfactory basis.
For the convenience of study, the fossil Echini may be separated into
three principal groups; viz. the Cidaritidæ, or Turban Echinites; the
Clypeasteridæ, or Buckler-shaped Echinites; and the Spatangidæ, or
Heart-shaped Echinites.
[Sidenote: CIDARITIDÆ.]
Cidaritidæ. _Turban Echinites._--In these sea-urchins the vent is
situated on the summit of the shell, and is surrounded by five minute
apertures for the exclusion of the ova. The mouth, or oral aperture,
is placed directly opposite, in the middle of the base, or inferior
surface. The mouth is large, and furnished with a powerful apparatus,
armed with teeth; which is sometimes found fossil (see _fig._ 1, 3,
_Lign. 101_). The structure of the animal, in consequence of the
symmetrical position of the two chief outlets of the shells, is
strictly radiated; that is, all the parts proceed from, or are arranged
around one common centre. The tubercles are larger and fewer than in
the other tribes of this family; they support long and powerful spines,
which vary much in form and ornament in different species (see _Lign.
102_). The larger tubercles and spines are beset with smaller ones,
disposed in regular series.
The Turban Echinites are the most ancient types of the order, some
forms appearing in the Carboniferous deposit. The species are very
numerous. The echinites of this group are subdivided into four tribes:
1. _Cidares_, properly so called.--In these the tubercles are
perforated; the ambulacra narrow, and beset with granular tubercles,
and the two lines of pores are close together. The pseudopodia can be
protruded to a great length, even beyond the spines, so as to reach
objects the latter could not touch.
2. _Echini_, which differ from the above in the tubercles being
imperforate, and the ambulacral area wide: the spines and tubes are of
a moderate size.
3. _Diademæ._--The tubercles are perforated, and the ambulacra wide and
studded with large tubercles.
4. _Saleniæ._--The tubercles are imperforate, and relatively large; the
chief distinction is a solid ovarian disk on the summit, composed of
several large flat plates, anchylosed together.
The case of the Turban Echinites is composed of twenty vertical series
of plates, the ambulacra, or porous grooves, forming continuous bands
from the summit to the mouth, which is armed with five angular teeth.
This tribe comprises many of the most elegant fossil species; those
which, from their shape and highly ornamented surface, have received
the popular name of Fairy's night-caps. The genus _Cidaris_, which
is characterized by perforated spinous tubercles, affords the most
beautiful examples, and these are occasionally found with the spines
in contact; a circumstance less rare than might be supposed, when the
nature of the attachment of these organs is considered; for, upon the
decomposition of the integument, and the ligaments which connect the
spines with the tubercles in a living state, these appendages quickly
fall off, even in recent specimens.
The interesting fossil figured _Lign. 100_ (_ante_, p. 311), is a
choice example of a Cidarite with the spines attached. This species
(_Hemicidaris crenularis_, _Agassiz_) is said to be characteristic
of the Upper Jura limestone of Switzerland, and was supposed to be
identical with Mr. Parkinson's _Cidaris parpillata var._ (_Pict.
Atlas_, pl. lvi. _fig._ 6), from Calne, in Wiltshire; but spines like
those of _Lign. 100_, do not occur in the English oolite. These spines
are not homogeneous throughout; the central part appears to have
been of a less dense tissue than the outer coat, as is shown in the
fractured spine in the figure. This structure does not exist in the
spines of the depressed Turban Echinites, but is stated by M. Agassiz
to prevail in all the species of the genus _Hemicidaris_, of which the
fossil figured in _Lign. 100_ is the type.
[Illustration: Lign. 101. Cidarites from the Oolite and Chalk.
Fig. 1.--Hemicidaris intermedia; view in profile, showing the
teeth projecting: 1/3 _nat._ _Calne._
2.--The same seen from above, displaying the outlet, and surrounding
pores.
3.--The same, view of the base, displaying the mouth, surrounded
by five angular bipartite teeth. The ambulacral
tubercles at the base are omitted in the figure.
4.--Diadema rotulare (_Agass._): viewed in profile: not.
5.--A siliceous cast of another species of _Diadema_. _South
Downs._
6.--View of the base of Diadema rotulare. This species
occurs in the so-called Neocomian Formation of France.
]
Cidaris (_Hemicidaris?_) intermedia, _Lign. 101, fig. 1, 2, 3._--The
shell of this echinite, from the Oolite at Calne, so closely resembles
that of _H. crenularis_, above described. that without the spines it
could not be distinguished.[298] It is of a depressed form, and has
very long subcylindrical spines; a specimen is figured _Lign. 102_,
_fig. 9_. It is this cidarite which occurs in such immense numbers in
the Oolite at Calne, Chippenham, Faringdon, &c. Slabs of limestone
are occasionally extracted from the quarries at Calne, with more than
thirty of these echinites surrounded by their spines. I have one
specimen, attached to a block of limestone, with fifty spines; but it
is difficult to detach a perfect spine.
[298] Mr. Woodward. I am indebted to this gentleman for many valuable
remarks on fossil Echinoderms.
[Sidenote: CIDARIS BLUMENBACHII.]
Cidaris Blumenbachii. _Lign. 127, fig. 3._--This is another beautiful
characteristic Turban Echinite of the Oolite. The tubercles are very
large and prominent, and the spines remarkably neat, being covered with
longitudinal granulated striæ; they are of an elongated cucumerine
form, and homogeneous in structure (_Lign. 127, fig. 5_). They occur
by hundreds in some of the layers of friable stone in the quarries
around Calne.
Many species of Turban Echinites abound in the White Chalk, especially
near Gravesend, Northfleet, Purfleet, Charlton, and other places
in Kent; the softness of the cretaceous strata in those localities
rendering the removal of the chalk an easy task. Splendid specimens,
with the spines and tubercles almost as fresh as if recent, have
rewarded the patience and skill of collectors. The British Museum
contains many fine examples, especially a specimen of _Cidaris
clavigera_ from Charlton, with sixteen spines, and the dental apparatus
_in situ_.[299]
[299] Several coloured figures of Cidarites and spines are given in
Pict, Atlas, pl. liii. and lvi. A fine series of Chalk specimens are
figured in Dixon's Fossils, tab. xxv.; many from the choice cabinet of
Henry Catt, Esq. of Brighton.
The collection of Chalk Cidarites with their spines, formed by W. H.
Taylor, Esq. F.G.S., of Winterslow-place, Brixton, is the most splendid
assemblage of these fossils I have seen.
Diadema. _Lign. 101, fig. 4, 6._--The shell in this genus is of
a more depressed form than in Cidaris; there are two rows of large
tubercles, which are crenulated and perforated, on the ambulacra as
well as on the interambulacral spaces. The spines are slender and
annulated. Mr. Woodward remarks that the common Chalk species referred
by authors to this genus, belong to the sub-genus _Cyphosoma_ of M.
Agassiz, in which the tubercles are imperforate. There are nearly fifty
fossil species known, and they range from the Lias to the Chalk. The
recent analogues inhabit the seas of warm regions.
Echinus.--The shells of the genus Echinus resemble those of Cidaris in
their general structure, but the tubercles are imperforate. More than
twenty fossil species are described, from the Oolite and Chalk.
Salenia.--In the greensand pits near Faringdon, in Berkshire, which
abound in fossil sponges and other poriferæ (_ante_, p. 228), there are
immense numbers of a small elegant Turban Echinite, which belongs to
the genus thus named by the eminent zoologist. Dr. J. E. Gray, of the
British Museum. The collector will easily recognize these sea-urchins
by the plated summit. The shell has five ovarian and five interovarian
plates, and an eleventh or odd one. The tubercles are crenulated. The
common species at Faringdon is _S. petalifera_, of Desmarest. Two
species of this genus, viz. _S. scutigera_ and _S. stellulata_, from
near Warminster, are figured in _Pict. Atlas_, pl. liii. _fig._ 12, 13.
_Cidarites of New Zealand._--Detached plates and spines of sea-urchins,
belonging to the family Cidaritidæ, have been discovered by Mr.
Walter Mantell, in the Ototara limestone of New Zealand; which is a
fawn-coloured stone, composed of foraminiferæ, like the Chalk, and
containing terebratulæ, corals, and teeth of sharks.[300]
[300] Geol. Journal, vol. vi. p. 319.
[Sidenote: SPINES OF CIDARITES.]
Spines of Cidarites. _Lign. 102._--Allusion has been made to the
immense numbers of the spines of two or three kinds of Cidarites that
occur in the oolitic limestones of certain localities. The spines of
other species and genera abound in the Chalk, Greensand, &c.; occurring
detached and intermingled with corals, shells, and the usual fossils of
those deposits. There is great variety in the form, size, and sculpture
of these organs. In the subjoined _Lign. 102_, a few distinct kinds are
represented.
[Illustration: Lign. 102. Fossil Spikes of Cidarites.
Fig. 1.--Spine of Acrocidaris nobilis (_Agassiz_).
2.-- ---- Cidaris cucumifera.
3.-- ---- ----- stemmacantha.
4.-- ---- ----- meandrina.
5.-- ---- ----- spinosa.
6.-- ---- ----- clunifera.
7.-- ---- ----- sceptrifera.
8.-- ---- ----- Parkinsoni.
9.-- ---- Hemicidaris intermedia.
]
Flint Casts of Turban Echinites. _Lign. 103._--The siliceous casts of
the shells of the Turban Echinites are interesting objects, for they
are often beautiful models of the interior. A specimen of this kind is
represented in _Lign. 101, fig. 5_. Casts of the larger Cidarites are
often seen on the ploughed lands of the South Downs, in beds of gravel,
and among the shingle on the sea-shore of chalk districts; appearing
as flattened spherical bodies, with a circular protuberance at each
pole, and vertical rows of nodular projections. Impressions of the
external surface of the cases are also frequent on chalk-flints, and
exhibit exquisite casts, in intaglio, of the mamillated tubercles, and
ambulacral grooves and pores.
[Illustration: Lign. 103. Echinital Remains in Flint. _Chalk. Lewes._
(_One-third the natural size._)
Fig. 1.--Cast of an Ananchyte, showing the form of the plates.
2.--Imprint of a segment of a Cidarite on a pebble.
_a._--One of the impressions of a spinous tubercle: _nat._
3.--Portion of an Ananchyte, having the cavity of the shell
covered at the bottom with flint, and lined above with
crystals of carbonate of lime.
]
A fragment of a flint, impressed by a portion of a Cidarite, is
represented _Lign. 103, fig. 2_. The perforations around the imprint
indicate tubular cavities in the flinty formed by the spines, and show
that these processes were attached to the shell when the latter was
enveloped by the fluid silex; the case and the spines having since
perished. But in the Chalk, exquisite specimens of Cidarites occur with
the case perfect, and filled with flint: examples of this kind are
often attached to a nodule by the slender column of silex that fills up
the aperture of the shell. The mineralized condition of the originally
friable calcareous cases of Cidarites and other Echini, is worthy of
attention: for whether the shell or spines be imbedded in chalk, flint,
or pyrites, if the structure and form remain, the constituent substance
is invariably opaque crystallized carbonate of lime, having an oblique
fracture.
As this conversion of a crustaceous envelope into calc-spar is
constant, it has probably resulted from the peculiar nature of the
original animal structures; but the cause of such transmutation is
unknown.
[Sidenote: CIDARITIDÆ OF THE PALÆOZOIC ROCKS.]
Cidaritidæ of the Palæozoic Rocks.--Three genera of this family,
comprising several species, have been discovered in the carboniferous
limestone of Northumberland and Ireland. One genus is undistinguishable
from Cidaris; and the species are placed under that name in Mr.
Morris's Cat. Brit. Foss.
These fossils have been figured and described by Prof. John Phillips,
and Col. Portlock. Prof. M'Coy, with his accustomed penetration and
sagacity, has ascertained, that notwithstanding the general resemblance
between the Cidarites of the secondary and those of the palæozoic
formations, the latter are constructed on an entirely different plan.
In the turban echini of the secondary, tertiary, and modern seas,
the interambulacral plates always consist of _two_ rows; but in the
palæozoic Cidarites there are _three_ or some greater odd number of
these plates. This eminent naturalist, therefore, places the earliest
type of Echinidæ at present known in the order _Perischoechinidæ_.
The case is spheroidal, formed of more than twenty rows of plates;
five ambulacra composed of two rows of pentagonal plates each; rows of
interambulacral plates, three, five, or more, terminating dorsally in
five large pentagonal ovarian plates.
As in the more recent forms, these Cidarites are separable into
two groups or families; one in which the spiniferous tubercles are
imperforate as in the Echinus (_Palæchinidæ_ of M'Coy); the other
with numerous small secondary tubercles and a few large primary
ones, perforated for the ligament of the spine as in Cidaris (the
_Archæocidaridæ_ of M'Coy).[301]
[301] Prof. Sedgwick's "British Palæozoic Fossils," p. 124.
Clypeastridæ.--The shell in this family of sea-urchins, is oblong or
rounded; the mouth is of an angular form, and situated in the middle
of the base or inferior face; it is furnished with well-developed
dental organs. The outlet is distant from the summit. The tubercles
are mere granulations, and the spines proportionally small. This group
is subdivided into two tribes: the Galeritidæ (_helmet-like_), and the
Clypeideæ (_buckler-like_).
Galerites albo-galerus. _Lign. 104._--The tribe of which this genus is
the type has the shell inflated, orbicular, oblong, or pentangular.
The ambulacra are simple, never petaloid; the poriferous zones extend
uninterruptedly from the summit to the mouth.
In the species figured _Lign. 104, fig. 1_, the shell is of a
conical form, in some varieties subpentagonal; narrowest at the hinder
part. The mouth is of a decagonal shape, and armed with teeth: it is
situated in the centre of the base (_Lign. 104, fig, 1a_); the outlet
is near the posterior margin of the base. The surface of the shell
is covered with granulations irregularly distributed. This species,
which received the name of _albo-galerus_, from its fancied resemblance
to the white conical caps of the priests of Jupiter, occurs in great
numbers and perfection in the Kentish chalk; it is less common in that
of Sussex. Siliceous casts of the shell are constantly found among the
drift and gravel, and on the ploughed lands of chalk districts; they
are popularly termed "_sugar-loaves_." The specimens obtained from the
chalk, when filled with flint, yield exquisite casts, if the shell be
dissolved in dilute hydrochloric acid; by this means the form of the
plates, and casts of the minutest ambulacral pores are obtained.
[Sidenote: ECHINITES FROM THE CHALK.]
[Illustration: Lign. 104. Echinites from the Chalk. _Lewes._
Fig. 1.--Galerites albo-galerus: _nat._
1_a_.--Base of the same, with the five teeth.
2.--Ananchytes ovatus: 1/2 _nat._
2_a_.--Base of the same.
]
[Illustration: Lign. 105. Holectypus (_Galerites_) inflatus.
_Kimmeridge Clay, Switzerland._
The left-hand figure shows the summit; the middle figure a profile; and
the right hand, a view of the base, with the mouth in the centre, and
the outlet towards the margin. (_M. Agassiz_).]
Holectypus (_Galerites_) inflatus. _Lign. 105._--In certain kinds of
Galerites, the shell is strengthened internally by five strong ribs
or projections, which of course leave corresponding deep furrows or
channels on the flint casts moulded in them; such fossils are not
numerous on the ploughed lands of the South Downs. These echinites
are placed by M. Desor in the genus of which an example is figured in
_Lign. 105_.
The shell is hemispherical, and circular; the base flat; the tubercles
are disposed in series; the inside of the case is supported by ribs.
[Sidenote: DISCOIDEA CASTANEA.]
Discoidea (_Galerites_) castanea. _Lign. 106._--The Galeritidæ, which
have a polygonal mouth, with the tubercles disposed in vertical rows
from the summit to the centre of the base, as in the Cidarites, instead
of being uniformly spread over the surface, as in _G. albo-galerus_,
are placed in the genus _Discoidea_, by M. Agassiz.
A species, in which the mouth is pentagonal, and the outlet on the
margin, occurs in the Chalk-marl of Sussex, Dorset, and the Alps; a
specimen is figured in _Lign. 106_.
[Illustration: Lign. 106. Discoidea (_Galeritcs_) castanea.
_Chalk-marl, Dorset._
Fig. 1.--Profile. The pores and plates of the ambulacra only are
inserted in this figure.
2.--View from above.
3.--The base, showing the central pentangular mouth, and
the vent in the margin.
]
The Clypeideæ differ from the tribe of echinites last described, in the
ambulacra being petaloid, that is, of a leaf-like shape, and disposed
in a stellated figure on the upper part of the shell. The ambulacra do
not extend to the mouth. The shell is generally of a depressed form;
and the petaloid ambulacra in many species appear like an elegant star,
richly fretted, spread over the shell. There are numerous species of
this type, both recent and fossil; many of the latter, being of a large
size, are beautiful objects in a cabinet of petrifactions.
Clypeus sinuatus (_Pict. Atlas_, pl. liv. _fig._ 1).--Of this genus,
which is the type of the tribe, a large species, _C. sinuatus_, is
very common in the Oolite of Wilts, Gloucestershire, and Oxfordshire,
and must be familiar to collectors. The shell is circular, and much
depressed; and has five petaloid ambulacra: the odd interambulacral
area forms a deep furrow in which the outlet is situated: the mouth is
median, pentagonal, and surrounded by a strong margin. The coloured
figures in _Pict. Atlas_, pl. liv. will enable the student to recognize
these fossils without difficulty. Splendid specimens of an allied
form (_Clypeaster_) occur in the tertiary limestone of Malta, (_Pict.
Atlas_, pl. lvi. fig. 7,) and are not uncommon in collections.
Nucleolites (_Wond._ p. 328).--There is a small type belonging to
this family, of which several species are so abundant in the Oolite,
Greensand, and Chalk-marl, that a brief notice of their characters may
be useful. The shell is oblong and inflated, rounded in front and flat
behind. The pores are united by grooves; the outlet is in a deep furrow
on the superior face; the mouth is sub-central. One species occurs in
the Tertiary strata, and there is a recent species inhabits the seas of
Australia. There are coloured figures of Nucleolites in _Pict. Atlas_,
pl. liv. fig. 5, pl. lv. figs. 6, 8.
Spatangidæ.--In this tribe of echinites, the case is oblong or
cordiform. The mouth, elongated transversely and destitute of proper
jaws, is situated in front of the centre of the base, near the
anterior border of the periphery. The outlet is towards the posterior
margin. The tubercles and spines are very small. Four subdivisions are
established, namely,--
1. _Ananchytes_.--A thick and oval shell; the ambulacra simple and
converging towards the summit; the mouth transverse; the outlet is
situated on the inferior face. (_Lign. 104, fig. 2._)
2. _Spatangus._--This name is now restricted to those Spatangidæ in
which the ambulacra are petaloid, the external row of pores slightly
elongated, and the inner rows round.
3. _Micraster._--By this term are now distinguished the Spatangidæ
which have the ambulacra depressed, and the shell cordiform. The
pores of the even ambulacra are united by a furrow. The vent is on
the posterior face. The common chalk Spatangus belongs to this genus.
(_Lign. 107._)
4. _Holaster._--The shells are heart-shaped; the ambulacra simple, and
converging towards the summit; the mouth is transverse; the outlet is
within the posterior face.
[Sidenote: ANANCHYTES OVATUS.]
Ananchytes ovatus. _Lign. 104. fig. 2._--These sea urchins are among
the most characteristic of the fossils of the Upper Chalk, and are
peculiar to the Cretaceous formation. They are readily distinguished by
their elevated helmet-like form, and by the transverse mouth and oblong
outlet situated on the inferior face of the flat base, and towards the
margin. (_Lign. 104. fig. 2^a._)
The vernacular names of "_Shepherd's Crown_," and "_Fairy Loaf_,"
indicate the form of these abundant fossils. The shell is oval in its
longest diameter; flat, or nearly so, below; and rounded, conical,
and somewhat laterally compressed towards the summit. The ambulacra
are five, between double lines of pores; the tubercles are minute and
scattered; the substance of the shell is of great thickness. More than
twenty species of the genus are known.
The helmet Echinites, like the preceding, have given rise to
innumerable siliceous casts, which are found associated with those
of other forms in the Drift, on the ploughed lands, and among the
shingle on the sea-shore; they are often placed as ornaments on the
mantel-shelves of the cottagers. A flint cast of an Ananchyte, in which
the plates were partially separated, is represented _Lign. 103, fig.
1_. The shells are sometimes filled with pyrites; and occasionally
are found partially empty, with crystals of calc-spar symmetrically
arranged on the inside of the shell, parallel with the rows of
ambulacral pores. _Lign. 103, fig. 3_, is a remarkable example, in
which flint occupies the base of the shell, while the upper surface is
lined with crystals of calcareous spar.
[Illustration: Lign. 107. Micraster (_Spatangus_) cor-anguinum.
_Chalk. Lewes._
Fig. 1.--View from above, showing the petaloid ambulacra.
2.--View of the base, with the mouth.
]
Micraster cor-anguinum (_Snake-heart_). _Lign. 107._--Of this genus
there are many species in the Chalk. This type of Spatangidæ are
more or less oval, elongated, and heart-shaped, wider before than
behind, with a sulcus, or furrow, in front. The shell is fragile,
and composed of large polygonal plates; the tubercles small and
irregularly distributed; the spines are short. The mouth is transverse,
situated anteriorly, and protected by a strong projection of the odd
interambulacrum, which is named the lip. The vent is terminal, and
placed above the margin. There are but four ambulacra, and these
are incomplete, comparatively of small extent, and situated in deep
furrows. A large and new species of Micraster (_M. cor-bovis_, of Prof.
E. Forbes), from the Sussex Chalk, is figured in Dixon's _Fossils_, pl.
xxiv. figs. 3, 4, p. 342.
[Sidenote: TOXASTER COMPLANATUS.]
[Illustration: Lign. 108. Toxaster complanatus.
_Greensand. Switzerland._
Fig. 1.--Profile.
2.--View of the summit, showing the _Vent_ at the side; _e_.
3.--View of the base, displaying the situation of the mouth,
and the union of the five _ambulacra_; their pores are not
introduced in figs. 2 and 3.
_a._ The narrow porous divisions of the shell, termed
_Ambulacra_.
_b._ Interambulacral spaces.
_c._ _Areæ_, or spaces covered by the wide plates.
_d._ The _Mouth_.
_e._ The _Vent_, or _Outlet_.
]
Toxaster (_Spatangus_) complanatus. _Lign. 108._--In this form of
Spatangus (constituting the genus _Toxaster Agass_.), the ambulacra
are not depressed or furrowed, as in the preceding echinites, nor
petaloid (_leaf-shaped_), as in those which M. Agassiz denominates true
Spatangi, but converge to a point on the summit, as is shown in _fig._
2; the external rows of pores are elongated horizontally, and form a
kind of furrow. The odd ambulacrum is in a deep groove. The mouth is
transverse, _fig._ 3, _d_; and at the anterior part of the inferior
face there is a depression, which results from the convergence of the
ambulacral areæ towards that point. The vent is in the posterior face.
This species is from the _Neocomian_ strata of France; I introduce it
to illustrate the characters of several other echinites, which the
French geologists suppose to be confined to the so-called Neocomian
formation; but which also occur in the Upper Greensand of Blackdown.
Holaster is another genus of Spatangidæ established by M. Agassiz, for
those echinites that are heart-shaped, with simple ambulacra converging
towards the summit. The mouth is elongated transversely; the outlet is
on the posterior face. A specimen first described in my _Foss. S. D._
(_pl._ xvii. _fig._ 9, 21), as Spatangus planus, is common in the Lower
Chalk, and Chalk-marl, and abundant in the Firestone Malm-rock.
* * * * *
Our limits will not allow of a more extended notice of the fossil
_Echinidæ_. The student should consult the Memoirs on the genera,
now in course of publication at the Government School of Mines, by
Professor Edward Forbes; the plates are exquisite, as works of art, and
the descriptions all that can be desired.
Mr. Dixon's work contains three excellent plates of cretaceous
Echinites. Several chalk species are figured in my Foss. South Down.
The numerous coloured figures of fossil sea-urchins in the Pictorial
Atlas of Organic Remains, have already been mentioned.
Geological Distribution of Echinites.--No vestiges of this order
of radiata have been discovered in the Silurian deposits: the
earliest known occurrence of any type is in the Carboniferous
formation. The most ancient Echinidæ, according to the present state
of our knowledge, are the Cidares, in the modified form previously
noticed,--_Archæocidaridæ_ (_ante_, p. 322).
In the Trias another type appears, _Hemicidaris_, which holds an
intermediate place between the Cidarites properly so called and the
Diadema.
In the Oolite, and Jurassic formations, numerous forms are for the
first time met with, constituting the genera Echinus, _Clypeus_,
_Disaster_, _Holectypus_, Diadema, Nucleolites, &c.
The Cretaceous seas swarmed with echini belonging to genera of which
no traces have been found in earlier rocks; viz. Holaster, _Salenia_,
_Micraster_, Salerites, Discoidea, _Ananchytes_, Cassidulus, &c.
In the Tertiary formations, Spatangus, Scutella, Clypeaster, and other
new genera appear, and many of the ancient ones are absent; or at least
have not been observed. Of the genera printed above in italics, no
living species are known.
[Sidenote: ON COLLECTING FOSSIL ECHINODERMATA.]
On collecting and developing fossil Echinodermata.--In the previous
remarks on the fossil remains of radiated animals, we have pointed
out those remains that are the most important and instructive, and
should be sought for by the student. Thus, in collecting Crinoids, the
receptacle or body should be the principal object of research, and if
only detached plates can be extracted from the rock, their relative
position should be carefully noted, and the specimens glued to a card
or board, in their natural order; and some of the ossicula of the
column, and of the arms, or tentacula, be placed with them.
Mr. Miller dissected specimens of every genus, and has figured
the separate plates or bones that enter into the composition of
the receptacle,[302] and arms. Traces of the tentacula, and their
subdivisions, must be sought for, and if discovered, should be removed
with the stone to which they are attached, and the block be afterwards
reduced in size by a mason's saw, and not by the blows of a hammer,
which might displace the ossicula.
[302] Natural History of the Crinoidea.
If imbedded in Lias shale, or other fragile material, a thick slab
should be removed, for greater safety in conveyance; this, when reduced
to a convenient size and thinness, may be imbedded in a tray with
plaster of Paris, or glued to a piece of thin, well-seasoned mahogany,
or deal. The specimens of the _Pear Encrinite_ of Bradford, and of the
Pentacrinites from Lyme Regis, in the British Museum,[303] were prepared
in this manner.
[303] Petrifactions, p. 78.
The crinoideal remains in Chalk belong but to few genera; they merely
require the usual manipulation of cretaceous fossils. The collector,
however, should remember that the ossicula and plates of the receptacle
(as for instance of the _Marsupites_), are but slightly adherent to
each other, and the chalk must not be wholly removed, or these parts
will become detached.
The receptacles of the Apiocrinites of the chalk are rarely found
with more than a few joints of the column attached; and I believe no
vestiges of the arms have been observed: these parts are therefore
desiderata, and should be diligently sought for: the radicles of these
crinoideans are long, articulated, and branching, and without due
caution may be mistaken for the arms, or for another species. The first
remark will also apply to the Marsupite; any specimens with but a few
ossicula of the arms are very precious. I may observe that there is yet
much to learn as to the number of species and genera, and the peculiar
characters of the Crinoidea of the chalk, and that any addition to our
knowledge on this subject will be valuable.
The _Asteridæ_ are so simple in form and structure, that it is
unnecessary to offer any suggestions for their development; of course
they must not be removed from the stone.
Among the detached ossicula dispersed through the chalk, the student
will remember that the large _madrepore-like_ tubercle of the
Star-fishes, (_ante_, p. 304,) may often occur. It may easily be
mistaken for an encrinital body, or for a coral, but an accurate
inspection will show that it is not composed of anchylosed plates, like
the receptacle of an Apiocrinite, but has surfaces for attachment to
other ossicula; while the ends, which in a crinoideal column would have
radiated surfaces, are rounded and entire.
In collecting Echinites, much caution is required in dissecting
specimens surrounded by spines. If imbedded in hard limestone, or in
laminated clay, it is scarcely possible to preserve the spines in
connexion with the shell; but it often happens that the Cidarites of
the Oolite are attached by the base to the solid limestone, and the
case with the spines is imbedded in sandy, friable aggregate, not
difficult of removal. A specimen in my cabinet, with upwards of fifty
spines attached to the shell, was obtained under such circumstances.[304]
[304] Now in the British Museum.
The Chalk Echinites will be found to possess spines more frequently
than is commonly supposed, if care be taken to explore the surrounding
chalk before it be removed. T have often procured Cidarites with
spines, when there were no apparent vestiges of these appendages, by
carefully scraping away the surrounding mass until the extremity of a
spine appeared, and then tracing it up to its connexion with the shell;
another point was discovered by further removal, and that was developed
in the same manner; and at length a Cidaris with several spines was
obtained. The chalk around the mouth should always be cautiously
removed in the dentated species, in the hope of preserving the teeth,
as in the specimens, _Lign. 101, fig. 1_, and _Lign. 104, fig. 1_.
As the shells of Chalk Echinites, when hollow, are often lined with
crystals (see _Lign. 103, fig. 3_), it is worth while to break
all indifferent specimens of the common species, with the chance of
obtaining an example of this kind.
The chalk must not be _scraped off_ from the crust or shell of the
Echinites, or the minute granulations and papillæ will be injured or
removed; it should be flaked off with a blunt point.
In friable arenaceous strata, as in some of the Maestricht and Tertiary
deposits, the Echinites may be extricated in as perfect a condition
as if fresh from the sea; it is, indeed, probable, from the habit of
these animals of burrowing in mud and sand, that in many instances they
were entombed alive by the sediment in which their fossil remains are
imbedded.
Beautiful Cidarites and their spines may be collected in the Oolitic
strata at Calne, Chippenham, Bath, &c.; and in the coralline Oolite
near Faringdon; and of Saleniæ, in the Greensand gravel-pits near that
town.
The Upper Greensand near Warminster, and at Chute Farm, near
Heytesbury, abounds in small Cidaritidæ and other echinites. The large
sinuated Clypeus is found in great perfection in the Oolite at Malton,
Cheltenham, Gloucester, &c.
The cretaceous echinites are to be met with in most localities of
the white chalk. The chalk-pits in Kent, especially at Gravesend,
Northfleet, Chatham, &c. are rich in Cidarites, and their spines.
The Galerites, and Ananchytes, are also very fine and numerous; and
the softness of the chalk renders their extrication from the stone a
delightful task for the young geologist.
Specimens of the common kinds of fossil Echinoderms may be obtained at
moderate prices of the dealers named in the Appendix.
There is a matchless suite of fossil Echinidæ in the British Museum,
which has been arranged and named by Mr. S. P. Woodward, and is now
the most instructive and interesting collection extant. It contains
examples of the following genera, viz., Ananchytes, Echinocorys,
Echinolampas, Holaster, Galerites, Cidaris, Diadema, Acrosalenia,
Glypticus, Disaster, Pygurus, Clypeaster, Scutella, Salmasis,
Echinocyanus, &c. There is also a good series of echinital spines.
CHAPTER X.
FOSSIL FORAMINIFERA--MICROSCOPICAL EXAMINATION OF CHALK AND FLINT.
"Where is the dust that has not been alive?"
Young.
That those infinitesimal forms of animal existence which swarm
throughout the waters of the ocean, but whose presence can only be
made manifest by the aid of the microscope, are preserved in a fossil
state,--that their durable remains constitute mountain ranges, and
form the subsoil of extensive regions,--and that the most stupendous
monuments erected by man are constructed of the petrified relics of
beings invisible to the unassisted eye,--are facts not the least
astounding of those which modern Geology has revealed.
This interesting field of research, which the labours of that eminent
observer M. Ehrenberg first made known, has since been explored
by other naturalists, and in every part of the world many of the
Tertiary and Secondary deposits have been found to contain microscopic
organisms in profusion. At present this branch of palæontology is in
its infancy, and it offers to the young student an inexhaustible and
most attractive path of scientific investigation; it possesses, too,
this great advantage over many others, that it can be pursued at home,
and the materials for its prosecution are everywhere at hand. Unlike
my explorations in the Wealden, in which a few fragments of bones, or
teeth, scattered at wide intervals through the rocks, and in localities
many miles apart, were often the only reward of a day's labour, here,
in the quiet of my study, I may discover in a few atoms of flint,
or grains of chalk, picked up by the road-side, the fossil remains
of beings as interesting and extraordinary as the extinct colossal
reptiles of Tilgate Forest.
[Sidenote: MICROPHYTES.]
The microphytes, or fossil Diatomaceæ, described in a previous chapter,
(_ante_, p. 93,) were formerly classed with the organisms that now
claim our attention, under the name _Infusoria_; from the belief that
generally prevailed among naturalists, of their animal origin. In fact,
some eminent microscopic observers, while admitting the vegetable
character of Xanthidium, Micrasterias, &c. consider the Naviculæ,
Ennotiæ, &c. as belonging to the animal kingdom.
Thus Dr. J, W. Bailey, in a late "Memoir on the Microscopic Organisms
in Various Localities of the United States," divides these bodies into
three groups; viz. _Infusoria_, _Desmidieæ_, and _Diatomaceæ_; with the
remark, that he has separated the two latter tribes from the Infusoria,
because so many distinguished naturalists consider them decidedly to
belong to the vegetable kingdom: "but," he adds, "while I believe that
no positive line of separation can be drawn between certain animals and
vegetables, I am yet disposed to regard the _Desmidieæ_, from the sum
of all their characters, as most nearly allied to admitted vegetables;
while the _Diatomaceæ_, notwithstanding Mr. Thwaites's interesting
observations on their conjunction,[305] still seem to me, as they have
always done, to be true animals. There is such apparent volition in
their movements, such an abundance of nitrogen in the composition
of their soft parts, and such resemblance between the stipitate
Gomphonematæ and some of the Vorticellæ, that I should be still
disposed to class them as animals, even if Ehrenberg's observations
of the retractile threads and snail-like feet of some of the Naviculæ
should not be confirmed."[306]
[305] The mode of fructification, or _conjunction_, as it is termed,
in the Algæ, consists in the adhesion of two cells or frustules
together, and their fusion into one; from their united contents a
mass of granular substance is produced, that becomes consolidated and
forms the spore or fruit, which, when arrived at maturity, is set free
by the bursting of the cell. Mr. Thwaites has ascertained that the
fructification is similar in the Diatomaceæ.
[306] Smithsonian Contributions, vol. ii. p. 34.
Thus, whilst referring Closterium, Arthrodesma, Euastrum, Xanthidium,
Micrasterium, &c. as vegetables, to the Desmidieæ, Dr. Bailey
places, _Actinocyclus_, _Campilodiscus_, _Coscinodiscus_, _Ennotia_,
_Navicula_, _Gomphonema_, _Pinnularia_, _Triceratium_, &c. among the
Diatomaceæ, as animals.
Of the animal nature of the microscopic objects which now require
our attention, there is however no question, although the zoological
position and affinities of many of the organisms included in this
survey are still but imperfectly determined.
The animals designated _Foraminifera_,[307] or Rhizopoda,[308] are of a
more simple structure than the Polypifera and Echinodermata described
in the previous chapters; yet as their relics are for the most part
presented to the notice of the geologist as aggregations of shells,
forming extensive beds of limestone, it will be convenient to treat of
them in this place.
[307] Foraminifera, _i.e._ bearing foramina--a name derived from the
minute openings in the shells and their septa.
[308] Rhizopoda; root-like feet; from the long fibrous processes, or
pseudopodia.
The fact that the fossil remains of Foraminifera, and of _Mollusca_,
alike consist of shells, and constitute strata identical in mineral
characters, and deposited under like physical conditions, renders the
examination of these Microzoa[309] a fit introduction to the study of
the durable remains of the higher order--the Mollusca.
[309] Microzoa; from μικρος, _mikros_, small, and ζωον, _zoon_, animal;
a convenient term to denote minute animal organisms whose forms can
only be defined by the aid of the microscope.
It is scarcely more than a hundred and twenty years ago, that the
existence of this numerous order of microzoa was first made known to
naturalists by _Beccarius_, who detected a considerable number of
species in the sand on the shores of the Adriatic. But the structure of
the animals that secreted these shells is a discovery of comparatively
modern date. The early collectors classed these microscopic bodies with
the shells of true mollusca; and even M. D'Orbigny, whose elaborate
researches justly constitute him a high authority in this branch of
natural history, in his first memoir, in 1825, described the involuted
discoidal forms as Cephalopoda. This error was corrected by the
investigations of M. Dujardin, who in 1835 satisfactorily demonstrated
that the Foraminifera are animals of the most simple structure, and
entirely separated by their organization from the Mollusca.
But the true nature of this class is so little understood by British
collectors of fossil shells,--of course I mean the uninitiated, and
the amateur naturalist, for whose use these unpretending pages are
designed,--that in order to invest the study of the fossil species with
the interest which a knowledge of the structure and economy of the
living originals can alone impart, I must give a history of the recent
forms somewhat in detail, taking M. D'Orbigny as my chief authority.[310]
[310] The best work for the student to consult is M. D'Orbigny's
"Foraminifères Fossiles du Basse Tertiaire de Vienne, Autriche." Paris,
1846. 1 vol. 4to. with plates. I rejoice to learn that a Monograph
on the British Foraminifera is in preparation by Dr. Carpenter and
Professor Williamson: than whom there are none more competent.
[Sidenote: FORAMINIFERA.]
The Foraminifera are marine animals of low organization, and, with but
few exceptions, extremely minute: in an ounce of sea-sand between three
and four millions have been distinctly enumerated. When living, they
are not aggregated, but always individually distinct; they are composed
of a body, or vital mass, of a gelatinous consistence, which is either
entire and round, or divided into segments, placed either on a simple
or alternate line, or coiled in a spiral, or involuted round an axis.
This body is covered with an envelope or shell, which is generally
testaceous, rarely cartilaginous, is modelled on the segments, and
follows all the modifications of form and contour of the body. From the
extremity of the last segment there issue sometimes from one, sometimes
from several openings of the shell, or through the numerous pores or
foramina, very elongated, slender, contractile, colourless, filaments,
more or less divided and ramified, serving for prehension, and capable
of entirely investing the shell.
The body varies in colour, but is always identical in individuals of
the same species; it is yellow, ochreous, red, violet, blue, &c.
Its consistence is variable; it is composed of minute globules, the
aggregation of which determines the general tint. It is sometimes
entire, round, and without segments, as in _Gromia_, _Orbulina_,
&c., which represent at all ages the embryonic state of all the
other genera. The animal increases by gemmation, each segment being
essentially distinct, but connected with the preceding one by a tube or
neck. When the body is divided by lobes or segments, the primary lobe,
as in the permanent condition of the Gromia, is at first round or oval,
according to the genus; once formed it never enlarges, but is enveloped
externally by testaceous matter.
The segments, which successively appear, are agglomerated together
in seven different ways, and these modifications are the basis of M.
D'Orbigny's classification. The discoidal forms, as the _Rotalia_,
_Rosalina_, _Cristellaria_, &c. are involute, like the Nautilus, and
divided by septa or partitions, which, like the enveloping shell, are
perforated. The lobes of the body _occupy contemporaneously every
chamber_, and are connected by a tube that extends through the entire
series. In the spiral form, as the Textularia, &c., the same structure
is apparent.
Whatever the form of the body, the filaments always consist of a
colourless transparent matter; they are capable of being elongated to
six times the diameter of the shell. They often divide and subdivide,
so as to appear branched; and though alike in form in the different
genera, vary much in their position. In some species they form a bundle
which issues from a single aperture, and is withdrawn into the same by
contraction; in others, the filaments project only through each of the
pores in that portion of the shell which covers the last segment: in
many they issue from both the large aperture and the foramina. These
filaments or pseudopodia fulfil in these animals the functions of
the numerous tentacula in the Star-fishes; serving as instruments of
locomotion and attachment.
Neither organs of nutriment nor of reproduction have been discovered.
In the genera having one large aperture from which the filaments
issue and retract, we can conceive nutriment to be absorbed by that
opening; but this cannot be the case in the species which have the last
cell closed up; in these the filaments issuing through the foramina
are probably also organs of nutrition. M. D'Orbigny considers the
Foraminifera as constituting a distinct class in zoology; though less
complicated than the Echinoderms and the Polypifera in their internal
organization, they have the mode of locomotion of the first; while by
their free, individual existence, they are more advanced in the scale
of being than the aggregated and immovably fixed animals of the latter
class.
But though I consider the animal of the Foraminifera as single, and
the additional lobes, or segments, as the continuous growth of the
same individual, I must state that some eminent naturalists regard
the entire structure as a series of distinct individuals, developed
by gemmation from the first formed segment, like the clusters of
the compound _Tunicata_; and not as a single aggregated organism,
made up of an assemblage of similar parts indefinitely repeated. In
a palæontological point of view, it matters not which opinion is
adopted.[311]
[311] See a masterly paper on the structure of Nummulina and Orbitoides,
by Dr. Carpenter; Geol. Journal, vol. vi. pp. 21-39, with admirable
representations of the structural details.
[Illustration: Lign. 109. Foraminifera.
_Chalk. Charing._
Fig. 1.--Globigerina cretacea; the original is 1/60 of an inch in
diameter.
2.--Textularia Globulosa; 1/40.
3.--Verneuilina tricarinata; 1/30.
4.--Cristellaria rotulata; 1/40.
5.--Rosalina Lorneiana; 1/40.
]
[Sidenote: CLASSIFICATION OF THE FORAMINIFERA.]
Classification of the Foraminifera.--The number of genera is so great,
that I can only attempt to convey a very general idea of the principles
of classification adopted by M. D'Orbigny, and give a few illustrations
of some of the most abundant fossil species.
That the reader may be cognizant of the usual aspect of these shells
five specimens from the Chalk, belonging to as many genera, are here
represented (_Lign. 109_); the deposit whence they were obtained will
be described hereafter.
As the mode in which the growth of the body, and consequently of the
shell, takes place, differs greatly in certain groups, an obvious and
natural arrangement is suggested, by which the class is divided into
seven orders:--
1. The primary, or simplest type; one segment or cell; as in _Orbulina_.
2. The segments arranged in circular lines; as in _Orbitolina_.
3. Segments disposed in a straight or arched single line; successively
increasing from the first to the last cell; as in _Nodosaria_, _Lign.
111_.
4. Segments, spirally and discoidally disposed, on the same plane, like
cells of the Nautilus; as in _Cristellaria_, _Lign. 109_.
The same type, but coiled obliquely, and inequilaterally, like the
shells of Gasteropoda; as in _Globigerina_, _Lign. 109_, _Rosalina_,
_Lign. 109_.
5. Segments developed alternately on the right and left of the
first, and successively on each side the longitudinal axis; as in
_Textularia_, _Lign. 109_.
6. Arrangement of the segments combining the modes of 4 and 5; that is,
the segments are formed alternately, but the whole are coiled spirally,
either obliquely, or on the same plane; as in _Amphistigena_.
7. Segments round a common axis, on two, three, four, or five, opposite
faces, returning after each entire revolution; the new cells being
placed exactly on the preceding series; as in _Quinqueloculina_, _Pict.
Atlas_, pl. lxii. _fig._ 12.
The Foraminifera vary considerably in magnitude; by far the greater
number of species are invisible to the unassisted eye, and the aid
of a lens or microscope is required to define the structure even of
the largest; yet many are of sufficient size to be recognized, as for
example the _Spirolinæ_, _Lign. 112_. A few genera are from a quarter
of an inch to nearly an inch in diameter, as the _Orbitoides Mantelli_
of the tertiary formations of North America,[312] and the _Nummulina_,
commonly termed _Nummulites_, of Europe, _Lign. 110_.
We will now describe the genera selected for illustration,
commencing with the large and well-known type, whose aggregated
remains form extensive beds of crystalline limestone in the Alps,
and in Asia, and Africa.[313]
[312] Dr. Morton's Synopsis of the Organic Remains of the Cretaceous
group of the United States. Philadelphia, 1824, p. 45, pl. v. fig. 9.
[313] Geol. Journal, vol. v.
[Illustration: Lign. 110. Nummulites, or Nummulina; _nat._
_From the Great Pyramid of Egypt._
Fig. 1.--Transverse section of a Nummulite, showing the form and
arrangement of the cells.
2, 3.--Specimens with part of the external plate removed.
]
Nummulina lævigata. _Lign. 110._--The shell is of a discoidal or
lenticular form, composed of numerous cells, concentrically arranged
round an axis on the same plane; both sides of the disk covered by a
smooth thick plate.
[Sidenote: NUMMULITES.]
Under the name of _Nummulites_, from their resemblance to a piece of
money, the fossil shells of this genus of Foraminifera have long been
known to naturalists, and are figured in many of the early works on
petrifactions. They occur in immense quantities in certain rocks, and
are of all sizes, from a mere point, to disks an inch and a half in
diameter; thus exceeding in magnitude all other animals of this class.
Perfect specimens appear as a calcareous solid circular body, of a
lenticular shape; smooth, and slightly convex on both sides, and
without any visible structure. On splitting the fossil transversely,
or rubbing down one of the convex planes, a series of minute cells,
arranged in a discoidal spire, is brought to view, as shown in _Lign.
110, fig. 1_. But this description gives a very inadequate idea of the
complicated and exquisite structure of the original, which has been
admirably worked out by Dr. Carpenter. This eminent physiologist has
shown that each chamber was occupied by a living segment, connected
with other segments by one or more tubular prolongations, which
absorbed nutrition from without, by means of filamentous pseudopodia,
that projected through a system of passages leading from the medial
plane to the external surface.[314] A figure of the supposed form of a
living Nummulina is given in Pict. Atlas, p. 187.
[314] Geol. Journal, vol. vi. p. 21. See also a paper by Prof.
Williamson, "On the minute Structure of the Calcareous Shells of some
recent species of Foraminifera." Trans. Microscop. Soc. vol. iii. p.
105.
The specimens figured in _Lign. 110_ are from the limestone that
forms the foundation rock of the Great Pyramid of Egypt, and of which
that structure is in great part composed. Strabo alludes to the
Nummulites of the Pyramids, as lentils which had been scattered about
by the artificers employed on those stupendous monuments, and become
stone.[315] Silicified masses of Nummulites are occasionally met with;
polished slices of such specimens are richly figured by the sections of
the inclosed Foraminifera.
[315] An interesting fact was communicated to me by a friend who
lately descended the Nile; the Nummulitic limestone rocks are in some
parts of the course of the river washed into the stream, and becoming
disintegrated, the Nummulites are set free, and re-deposited in the
recent mud of the Nile.
The Nummulitic limestones are of the Eocene or ancient. Tertiary epoch,
as the labours of Sir Roderick Murchison in the Alps, Apennines, and
Carpathians first established: Nummulites are unknown in the Secondary
formations.[316]
[316] Geol. Journal, vol. v.
Orbitoides.--The fossil bodies thus named are disciform, like the
Nummulites; and one species, which forms the constituent substance
of ranges of limestone mountains, 300 feet high, near Suggsville, in
North America, was first described by my lamented friend, the late
Dr. Morton, of Philadelphia, as _N. Mantelli_, in his work on the
Cretaceous Fossils of the United States.
The discovery that the Nummulitic deposits of the Old World were of
the tertiary period, directed attention to their supposed geological
equivalents in America; and on a careful examination of their fossils,
the rocks proved to be tertiary, and the shells true Foraminifera
allied to the Nummulites, but generically distinct.[317] A reference to
Dr. Carpenters memoir, previously cited, is necessary to comprehend the
complicated structure of these fossils.[318]
[317] Manual of Geology, p. 208.
[318] Geol. Journal, vol. vi.
Siderolina, or _Siderolites_, is a genus of Foraminifera, which may
be described as Nummulites, in which the turns of the spire are
intercepted by elongated appendages, that project beyond the periphery
of the disk, and produce a stellated figure. These fossils abound in
the cretaceous strata of Maestricht.
Fusulina.--The shell is fusiform, being elongated transversely to
the axis; the cells are divided internally by constrictions. Only
one species is known, (_F. cylindrica_,) and this is confined to the
Carboniferous formation; it is the most ancient or earliest type of the
class, according to the present state of our knowledge.
[Illustration: Lign. 111. Foraminifera, &c.
Fig. 1 and 2.--Campilodiscus; a perfect frustule, and part of another,
seen from above, Tertiary; Egra in Bohemia. _See ante_, p. 96.
3_a_.--Lituola nautilotdea. _Chalk, Chichester._ (By Mr. Walter
Mantell.) Side view, × 8.
3_b_.--Front view of the last cell of 3d, to show the foramina with
which it is pierced.
3_c_.--The last cell of 3_a_.
3_d_.--Side view of a young shell, before the produced, or straight
part appears, × 20.
4_a_.--Flabellina Baudonina. _Chalk._ (M. D'Orbigny.) A young
individual seen in profile, × 12.
4_b_.--The same, viewed laterally, shows the oblique arrangement
of the cells.
5.--Nodosaria. _Chalk, Chichester._ (By Mr. Walter Mantell.) The
line below indicates the natural size.
]
[Sidenote: NODOSARIA. LITUOLA.]
Nodosaria. _Lign. 111, fig. 5._--Straight, elongated cells placed
end to end, separated by constrictions; the last formed cell has a
round central aperture. Several beautiful species abound in the Chalk;
specimens often occur adhering to the surface of the flint nodules.
Nodosariæ are abundant in tertiary deposits. Mr. Walter Mantell
discovered Foraminifera of this genus in the blue clay of Kakaunui, in
New Zealand.
Cristellaria. _Lign. 109, fig. 4._--The shell is in the form of a
compressed Nautilus; it has a single aperture, which is situated at the
angle of the keel; the cells are oblique.
This genus comprises seventy fossil species, which occur in the Lias,
Oolite, and Chalk. Living species are abundant in almost every sea.
Flabellina. _Lign. 111, fig. 4a_.--In a young state, this shell,
like the preceding, resembles that of a Nautilus, and the cells are
oblique; but in the adult, are of a zigzag (chevron) form. It has a
single round aperture. _Fig. 4a_ shows a young individual, seen in
profile; _fig. 4b_ a lateral view, exhibiting the obliquity of the
cells.
Species of Flabellina are often found in cretaceous strata. The genus
is not known in a recent state.
Polystomella.--In its general form this genus resembles the other
nautiloid shells above described, but its structure differs
essentially; for there are several apertures along the side of the
shell, as well as the opening in the last segment. The cells are
simple, and each is a single cavity. The figures and details of
structure, given by Professor Williamson, must be referred to, for an
insight into the organization of this beautiful and complicated type
of Foraminifera.[319] One species of Polystomella is said to occur in
the Chalk; I have not detected this genus in our cretaceous deposits.
Recent species swarm in our seas; and may be easily obtained from the
mud and sand on the shores at Brighton.[320]
[319] Trans. Microscop. Society, vol. ii.
[320] Mr. Poulton has specimens of the shells, and the bodies of the
animals deprived of the shell, mounted for the microscope.
Lituola. _Lign. 111, fig. 3a._--In a young state the shell is
nautiloid, as in _fig. 3b, 3d_; but becomes produced by age, and
assumes a crosier-like form, as in _fig. 3a_. The cells are filled
with a porous testaceous tissue, as shown in _figs. 3b, 3c_; which
also illustrate the foraminiferous character of the shells in this
class of animals; for both the external testaceous covering, and the
septa of the cells, exhibit perforations.[321]
[321] The perforations are omitted, by mistake, in the figure of the
adult shell, _fig. 3a_.
[Illustration: Lign. 112. Spirolinites in Flint.
_Chalk. Sussex._
(_By the late Marquis of Northampton._)
The specimens are only sections of the shells Imbedded in flint, and
seen as opaque objects with a lens of moderate power. The small figures
denote the size of the originals.]
[Sidenote: SPIROLINA.]
Spirolina. _Lign. 112._--The general form resembles that of Lituola:
the young shell being a discoidal, involute, and becoming produced
by age; but the internal structure is different; the cells are simple
cavities.
The chalk and flints of Sussex abound in these crosier-like shells,
whose existence in the cretaceous rocks was first made known by my
deeply lamented friend, the late Marquis of Northampton. The annexed
lignograph, from drawings by his lordship, shows the form and structure
as displayed by sections in fractured flints. Four species were named
by Lord Northampton (see _Wond._ p. 32-5); but it is doubtful whether
all the specimens belong to more than one species; the apparent
diversity of structure may arise simply from the different planes in
which the sections happen to have been made.
Globigerina. _Lign. 109, fig. 1._--The shell is turbinated, the cells
are spheroidal, and the last, or terminal one, has a semilunar aperture
at the umbilical angle. Several fossil species abound in the Chalk and
in the tertiary deposits; and many living species swarm in our seas.
[Illustration: Lign. 113. Nonionina Germanica, × 290.
A recent specimen of the body of the animal; the shell removed by acids.
_From the North Sea, Cuxhaven._ (_M. Ehrenberg._)
_a, a._--Naviculæ and other organisms in the segments of the animal.]
Nonionina.--_Lign. 113._--A nautiloid shell, with simple cells; the
last cell has a single narrow aperture placed transversely over the
dorsal aspect of the spire. One species occurs in the chalk formation
of Germany; several in tertiary deposits, and in the existing seas.
The figure, _Lign. 113_, represents the body of the animal deprived of
its shell, to illustrate the nature of certain fossils from the Chalk.
[Illustration: Lign. 114. Foraminifera in Chalk and Flint. × ×.
(_Seen by transmitted light._)
Figs. 1, 2, 3, 6.--Different forms of Rotalia.
2.--Resembles the recent Rotalia stigma; Ehrenberg;
from the North Sea, near Cuxhaven.
4.--Portion of a Nautilus, showing five chambers, partially
separated, each pierced by the siphunculus: in Flint, from
Ireland.
5.--The body of a Rotalia, in Flint; the shell is not
apparent.
]
[Sidenote: ROTALIA--ROSALINA.]
Rotalia. _Lign. 114._--The shell, though nautiloid in its contour,
is regularly turbinated, the cells not globular; the last cell has
a central, semilunar, transverse, aperture. There are fifty fossil
species. The Rotaliæ appear in the Lias, Oolite, and Chalk, in immense
numbers, and swarm in the present seas.
Rosalina. _Lign. 109, fig. 5._--The shell is depressed; the spire
apparent on one side; the aperture is a prolonged slit extending from
one cell to another, and opening on the umbilicus; that is, on the
side opposite to the spire. There are eighteen fossil, and many recent
species of this genus.
Textularia. _Lign. 109._--This, and the following genus, belong to
that order of Foraminifera in which the segments or cells are arranged
in two or three distinct axes (_ante_, p. 342), and by their gradual
increase give rise to an elongated conical but not spiral shell, which
in its general outline resembles that of certain gasteropoda, but is
easily distinguished by its internal structure. The shell is conical,
compressed, formed of alternate cells, with a transverse aperture
placed on the inner side. Upwards of thirty fossil species are known.
The Textulariæ are in great abundance in the cretaceous rocks; and,
together with Rotaliæ and Rosalinæ, constitute a large proportion of
the minute organisms of the secondary formations as well as of the
present seas.
Verneuilina.--_Lign. 109, fig. 3._--A turriculated shell, with a slit
or aperture transverse to the axis of involution, and placed on the
umbilicus. This genus, of which but one species is known, is peculiar
to the cretaceous deposits.
* * * * *
[Sidenote: CHALK ANIMALCULITES.]
Strata composed of Foraminifera.--From this concise exposition of
the characters of the genera that most frequently occur in a fossil
state, we pass to the examination of the organic composition of those
limestones which are in a great measure made up of the debris of
Foraminiferæ. We will commence the investigation with that common
substance, the white chalk of the South-East of England.
It has long been known that a large proportion of the purest white
chalk consists of minute chambered shells,[322] and corals.
[322] Often termed _Polythalamia_, meaning many chambers or cells.
Mr. Lonsdale, some years since, first showed that by brushing chalk in
water, and examining the sediment, shells, corals, and foraminifera
might be obtained in abundance; but it was not at that time suspected
that the residue of the detritus was almost entirely composed of
distinct organic structures, so minute as to require high magnifying
powers, and a peculiar mode of manipulation, for their detection and
definition.
M. Ehrenberg demonstrated that even the fossils discovered by Mr.
Lonsdale are colossal, in comparison with the infinitesimal structures
of which the finer particles of the chalk consist; for one cubic
inch of the limestone is found to contain upwards of a million of
well-preserved animal organisms.
The chalk, therefore, is an aggregation of extremely minute fossils
and inorganic particles. The yellow, soft, writing chalk of the North
of Europe, according to M. Ehrenberg, is composed of about half its
mass of organic remains; but in the chalk of the South of Europe, the
fossils predominate. The amorphous atoms of the cretaceous limestone
do not, as was formerly believed, arise from a precipitate of lime
previously held in solution, but from the disintegration of the
assembled organisms into more minute calcareous particles; and these
have subsequently been reunited by a crystalline action, into regular,
elliptical, granular, bodies.
M. Ehrenberg infers that the compact flint nodules have originated from
an aggregation of pulverulent particles of siliceous organisms; and
upon this hypothesis explains the absence of flint nodules, and the
abundance of siliceous infusoria, in the beds of marl that alternate
with the chalk in the south of Europe, and their presence in the chalk
of northern Europe, in which the marls are wanting. In other words,
he supposes, that in the former case the siliceous shells of the
animalcules were spread abroad and deposited in layers or strata; and
in the latter were aggregated into nodular masses. This opinion is not,
however, supported by facts; for, though the animal origin of lime,
flint, and iron, may be admitted to a great extent, yet the deposition
of silex and lime from aqueous solutions, is carried on at the present
moment upon an enormous scale; and it cannot be doubted that to such a
process is attributable the formation of the nodules, layers, dikes,
and veins of flint, which traverse the chalk, and other rocks.[323]
[323] See my "Memoir on a Microscopical Examination of Chalk and Flint,"
Annals of Nat. Hist., Aug. 1845.
The most abundant microscopic organisms in the English chalk and flint
which I have examined, are _Rotaliæ_, or _Rosalinæ_, and _Textulariæ_.
Immense numbers of minuter Foraminifera also occur, and many shells,
which are unquestionably the young state of testaceous Cephalopoda (as
_Nautilus_, _Ammonite_, &c.).
Spines of Sponges, and of Echinoderms, also frequently appear in the
field of the microscope: and a spongeous structure is so common in
flint, that an eminent observer conceives that all the flints, both
nodular and tabular, have originated from poriferous zoophytes;[324] an
hypothesis altogether inadmissible.
[324] "Memoir on the Siliceous Bodies in the Chalk, Greensands, and
Oolite," by J. S. Bowerbank, Esq. F.R.S. &c. Geol. Trans, vol. vi. p.
181.
The assertion that the chalk every where consists almost wholly of
organic bodies must likewise be accepted with some limitation. The
assiduous observer who searches for hours chalk and flint carefully
prepared, and with the aid of an excellent microscope, though he
will meet with immense numbers of organisms, will often find a great
proportion of atoms without traces of structure. Neither is there
much variety in the easily recognizable forms of the English chalk (I
write from my own limited experience); many of the species described
by M. Ehrenberg, and others, are few and far between; and I have not
detected a single example of diatomaceæ. The student therefore must
not be discouraged, if, after perusing the glowing accounts of the
discoveries of M. Ehrenberg, he should not be more successful than
myself. It must, however, be borne in mind, that as the fossil remains
of the larger animals and plants are commonly associated together
in particular localities, while in similar rocks in other districts
they are altogether wanting; in like manner, some strata of the same
series may be made up of organic bodies, while others are destitute of
them. In fact, such is the case with our English Chalk: some layers in
the cliffs at Dover are literally an aggregation of foraminifera and
corals, while other beds have but few vestiges of organic remains.
[Sidenote: CHALK FORAMINIFERA.]
[Illustration: Lign. 115. Chalk-dust; chiefly composed of Foraminifera;
_highly magnified._
(_Seen by reflected light._)
_a, a._ Rotaliæ. _b._ Textulariæ.]
Foraminifera of the Chalk and Flint. _Lign. 115._--If a few grains
of soft white chalk from Gravesend or Dover be examined under a high
power (1/4 inch object-glass of Ross), groups of foraminifera will be
perceived, chiefly of Rotaliæ, Rosalinæ, and Textulariæ, as shown in
_Lign. 115_. If some of the powder be immersed in Canada balsam, (as
directed in the instructions at the close of this chapter for preparing
chalk for microscopical examination,) the outline of the shells, and
the cavities of, the cells, will be apparent; as in the sketches
_Lign. 114_, _ante_ p. 351. If a chip or slice of flint, rendered
transparent by immersion in oil of turpentine or Canada balsam, be
viewed first with a low power, (1 inch object-glass,) to discover a
good specimen, and afterwards under a high magnifier, (a 1/4 or an
1/8 object-glass,) the form of the shell and of the cells will be
distinctly seen, as in _Lign. 116_. In this beautiful fossil Rotalia,
the segments are as sharply defined as in a recent example: and one of
the cells (_a_) is seen to be lined with quartz crystals.
[Illustration: Lign. 116. Section of a Rotalia in flint.
(_Seen by transmitted light, and showing the chambers partially filled
with mineral matter._)
_a._ A cell lined with spar.
(× 250 _diameters_.)]
At first sight this fossil might be mistaken for a nautilus partially
filled with spar; but the reader will remark that the septa, or
partitions, have their convex surface towards the aperture; whereas
in the shells of the Cephalopoda (Nautilus, Ammonite, &c.) the septa
are concave anteriorly. In _Lign. 114_, _fig._ 4, a series of casts in
flint of the septa of a young Nautilus is represented; by comparing it
with the Rotaliæ in the same lignograph, _figs._ 2, 3, this distinction
will be obvious. And here it may be necessary again to point out the
essential character of the animal of the foraminifera, as distinguished
from that of the cephalopoda with chambered shells. In the latter,
the body of the mollusk only occupies the large outer chamber; the
internal compartments are empty dwellings, which the animal has
successively quitted in the progress of its growth, and with which
it has no connexion except by the siphunculus. In the Rotalia, and
allied forms, the body of the animal is inclosed within the shells, and
occupies every chamber contemporaneously at every stage: the cells are
always filled by the segments of the body. Hence when the shell, which
is calcareous, is dissolved in weak hydrochloric acid, the soft body
is exposed, and seen to extend to the innermost chamber. The segments
are connected by a membranous tube, which some naturalists regard as
a common channel of communication between the several digestive sacs
of which the body consists; for minute diatomaceæ which the animal has
swallowed, (according to Ehrenberg,) are seen within the membranous
sacs; as shown in _Lign. 113_, which represents the body of a
Nonionina, deprived of its shell. The importance of obtaining a correct
idea of this structure will presently appear.
When a recent Rotalia is immersed in dilute acid, the soft parts of
the body, deprived of the shell, may be obtained entire; they consist
of a series of little bags or sacs, united by a tube. The constituent
substance appears to be a tough membrane, and is generally of a rich
brown or amber colour. The sacs are sometimes full of a granular
substance, but are often empty and collapsed.
[Sidenote: FOSSIL BODIES OF ROTALIÆ.]
Fossil remains of the soft parts of Foraminifera. _Lign. 113._--When
examining chalk[325] and flint under the microscope with the view of
discovering the fossil bodies described by M. Ehrenberg, I observed
that the cells of the Rotaliæ in flint were frequently occupied by a
substance varying in colour from a light amber to a dark brown, and
closely resembling in appearance the body of the recent foraminifer
deprived of its shell. Under a high power, the folds of the membranous
sacs and the connecting tube were apparent, and I felt convinced that
the substance filling the cells was not inorganic, but the original
animal tissues in the state of molluskite.[326] In short, that the
animal had become immersed and preserved in the fluid silex like the
insects in amber. The appearance of the first discovered example of
this kind is represented in _Lign. 117_.
[325] In 1845.
[326] _Molluskite_: a name by which I proposed to distinguish the
carbonaceous substance resulting from the soft bodies of testaceous
mollusca.
[Illustration: Lign. 117. Rotalia in Flint, with the fossilized body of
the animal in the shell: _highly magnified_.
(_Seen by transmitted light._)]
[Sidenote: SOFT BODIES OF FORAMINIFERA.]
In a paper read before the Geological Society in 1845,[327] I
ventured to affirm the animal nature of the fossils in question; but
the supposition was regarded by geologists as very startling and
unsatisfactory; and as the specimens were enveloped in flint, the
appearance was attributed to the infiltration of mineral matter of a
different colour from the surrounding silex, into the empty chambers;
a circumstance of frequent occurrence in Ammonites, Nautili, and even
in the foraminifera; for the latter are often filled with chalk, flint,
silicate of iron, crystal, &c. as in _Lign. 116_. In these instances,
I conceive the shells were either empty when immersed in the fluid
chalk or flint, or speedily became so by the decomposition of the soft
parts of the animal. But in the fossils under consideration, I believe
the live animal was suddenly enveloped, and hermetically sealed, as
it were, in its shell, and that putrefaction was thus prevented.
The uniformity in colour, and the structure of the substance in the
cells, appeared to me incompatible with its assumed mineral origin,
and I resolved to follow up the inquiry by an examination of Rotaliæ
in chalk; in the hope that by dissolving the shell in acid (as in
recent foraminifera), the body of the animal might be detected in an
unmineralized state. After many fruitless attempts, several examples of
the soft bodies of Rotaliæ were obtained from the grey chalk of Dover,
in an extraordinary state of preservation.[328]
[327] Notes of a Microscopical Examination of the Chalk and Flint of the
South-East of England, with Remarks on the Animalculites of certain
Tertiary and Modern Deposits. Published in the Ann. Nat. Hist., Aug.
1845.
[328] To Henry Deane, Esq. of Clapham Common, I am indebted for some of
the most illustrative specimens hitherto obtained.
[Illustration: Lign. 118. The Soft Bodies of Foraminifera; extracted
from Chalk: _highly magnified_.
(_Viewed by transmitted light._)
Fig. 1.--An exquisite example of the body of a Rotalia; the sacs
partially collapsed.
2.--Body of a Rotalia; the sacs distended with a dark granular
substance.
]
These marvellous relics were obtained by subjecting a few grains
of the chalk to the action of weak hydrochloric acid, by which the
calcareous earth and the shells it contained were dissolved; the
residue, consisting of particles of quartz and green silicate of iron,
and remains of the animal tissues, were placed, in the usual manner, in
Canada balsam. Two exquisite specimens of the bodies of Rotaliæ thus
obtained are figured in _Lign. 118_.[329]
[329] I communicated this discovery to the Royal Society. See Philos.
Transactions, 1846, p. 465.
In these fossils the sacs are generally more or less distended with
a dark substance, as in _Lign. 118, fig. 2_: but in some, they are
empty and collapsed in folds, just as membranous pouches would appear
under similar conditions; as in the exquisite fossil, _Lign. 118,
fig. 1_.
The sacs regularly diminish in size from the innermost to the outermost
cell, and vary in number from fourteen to twenty-six; being more
numerous than in the recent species of Rotaliæ that have come under my
notice. In some instances small papillæ are seen on the outer surface
of the integument; apparently the vestiges of the pseudopodia.[330]
[330] Admirably as my excellent engraver, Mr. Lee, (of Prince's Square,
Kennington,) has executed the lignograph, 118, I would refer the reader
to the steel plate in Philos. Trans. 1846, pl. xxi. for figures of
these marvellous fossils.
Not only is the form and general character of the animal substance
preserved, but even its flexibility; for in one instance, the body,
released by the solution of the chalk and shell, was uncoiled and
pressed out, as shown in _Lign. 119, fig. 4_.
In one specimen, (figured in _Philos. Trans._ 1846, pl. xxi. _fig._
10,) the membrane of the largest sacs is much corrugated, and disposed
in numerous duplications, probably owing to the empty state of these
segments, when immersed in the chalk; but the discoidal contour of
the original is well preserved. This fossil so closely resembles the
decalcified body of a recent Rotalia or Rosalina, that an eminent
observer who saw it under the microscope at the meeting of the Royal
Society, without knowing its history, concluded it to be the body
of a recent animal. This extraordinary preservation of the soft
delicate tissues of an animal of the cretaceous seas, invisible to the
unassisted eye, through the incalculable ages that must have elapsed
since the deposition of the chalk in which it was enshrined, is a fact
as remarkable as the occurrence of the carcass of the Lena Mammoth, in
the frozen soil of Siberia.
[Sidenote: FORAMINIFERA IN CHALK AND FLINT.]
[Illustration: Lign. 119. Remains of Foraminifera; in Chalk and Flint.
(_Viewed by transmitted light; highly magnified._)
Fig. 1.--Shell of a Rosalina, filled with mineral matter; in flint.
2.--Soft parts of a Textularia; in flint.
3.--Cells of Textularia elongata; filled with mineral
matter; the shell not visible; in flint.
4.--The soft body of a Rotalia, deprived of its shell, and partially
uncoiled; obtained from Chalk, × 450 _diameters_.
]
The soft parts of other foraminifera have been discovered in a similar
state of preservation. A fine example of the body of a Textularia, in
flint, is figured, _Lign. 119, fig. 2_.
The form and disposition of the segments in _Textularia elongata_,
is shown in _Lign. 119, fig. 3_. These cells are filled with
inorganic matter. The shell of a Rosalina filled with an opaque mineral
substance, forming casts of the cells, is represented in _Lign. 119,
fig. 1_.
The preservation of the soft parts of foraminifera and of mollusks, in
a fossil state, is a phenomenon of frequent occurrence, and no longer
questioned by geologists, notwithstanding the scepticism with which my
first announcement of the fact was received. Dr. Bailey, of West Point
Military Academy, soon after the publication of my first paper, sent me
specimens from the marls of New Jersey.
Foraminiferous Limestones of India.--So much doubt was expressed as to
the accuracy of my opinion respecting the nature of the fossil Rotaliæ,
that its corroboration by observations on certain limestones in India,
by H. J. Carter, Esq. Secretary of the Bombay Royal Asiatic Society,
was as gratifying as unexpected. According to the researches of that
gentleman, the south-east coast of Arabia is chiefly composed of two
distinct limestone formations; the one averaging about 4,000 feet above
the level of the sea, and the other 600 feet. The latter forms the
desert of Akaf, and with the intervention of the mountains of Oman,
which belong to the greater formation, passes up into the lower Sindh;
while the former constitutes the high land of the coast, which, parting
from the western border of the Desert of Akaf, extends nearly to Cape
Aden.
The limestones of both these groups, or formations, consist chiefly of
foraminifera; the largest forms being visible to the naked eye. Mr.
Carter states that his attention was first directed to the organic
composition of the Porebunder limestone, which is imported into Bombay
for building, by small amber-coloured specks on the stone, that
resembled the soft parts of foraminifera figured and described by me
in the Philosophical Transactions. "On subjecting a portion of the
limestone to the action of acid, I found them to be what Dr. Mantell's
observations had led me to expect, the actual remains of the animals,
of exquisite beauty in form and symmetrical development. The minute
kinds in the Porebunder stone do not average more than 1/900 of an inch
in diameter; and the composite forms are held together by thread-like
attachments, which indicate the tubular communications that existed
between them when living."[331]
[331] "On the Existence of Beds of Foraminifera, Recent and Fossil, on
the South-East coast of Arabia," by H. J. Carter, Esq.; Proceedings of
the Bombay Royal Asiatic Society, 1848,
[Sidenote: FORAMINIFEROUS DEPOSIT AT CHARING.]
Foraminiferous Deposit at Charing. _Lign. 109._--The little town of
Charing, in Kent, has acquired a celebrity among those naturalists who
are interested in the present inquiry, by the researches of William
Harris, Esq. F.G.S. who some years since made known the existence of
a remarkable deposit of chalk detritus, about one foot in thickness,
which extends over the outcrop or exposed surface of the firestone in
that locality.
This bed consists of a soft, whitish, tenacious clay, which, when
immersed in water, is found to be largely composed of minute grains,
that prove to be foraminifera. These shells belong to many species
and genera; and are associated with the cases of entomostraceous
crustaceans, spicula of sponges, &c. The organisms readily separate
from the amorphous particles by washing, and specimens may be easily
obtained as distinct and perfect as if recent. See _Lign. 109_, _ante_,
p. 342. Intermingled with the cretaceous forms, are minute fresh-water
shells, apparently derived from a modern source.
The Charing deposit appears to have originated from the action of water
on the unconsolidated chalk of the neighbouring Downs, before the
surface of the hills was protected by a covering of vegetable soil.
Through the liberality of Mr. Harris, I have been able to examine an
extensive series of the Charing Foraminifera; and Prof Williamson has
figured and described the principal types in an interesting memoir in
the Transactions of the Manchester Philos. Soc. vol. viii. 1847. As in
most of the cretaceous strata, the prevailing species are referable to
the genera Textularia, Rotalia, Rosalina, Cristellaria, Lagena,[332]
&c. There are numerous spicula of sponges, and needle-like calcareous
prisms, which are the detritus of the fibrous shells, called Inoceramus.
[332] This interesting type of Foraminifera is the subject of a Memoir
by Prof. Williamson; Annals, Nat. Hist. 1848, vol. i.
Foraminifera of the Oolite, Lias, &c.--The occurrence of certain genera
in particular rocks has been incidentally noticed in the previous
descriptions, and it is needless to particularize any localities of
the Oolite, Lias, and other secondary deposits. It must suffice to
state that Dr. Carpenter, Prof Williamson, Prof Phillips, Mr. Sorby,
Mr. Rupert Jones, and other able observers, have figured and described
foraminifera from the strata between the Chalk and the Carboniferous
formations: the report to be drawn up by the two first-named gentlemen
for the British Association, will present a resume of the British
fossil genera and species.
It is deserving record, that no vestiges of foraminifera have been
found in the Wealden strata; the fluviatile origin of those deposits
renders it improbable that the remains of these marine organisms should
occur in great numbers, yet from, the estuary character of some of the
beds, the presence of foraminifera might be expected.
Foraminiferous Deposits of the United States.--Dr. Bailey has made us
familiar with the foraminiferous rocks of North America. The various
memoirs on this class of fossil animalculites, and on the diatomaceæ
(_ante_, p. 93), published in the American Journal of Science, and in
the Smithsonian Transactions, attest the acumen, and unwearied spirit
of research, of this able observer. Not only from the United States,
but from numerous localities in Asia and Arabia, Dr. Bailey has
transmitted me specimens of limestones containing foraminifera, chiefly
of the genera Rotalia and Textularia.[333]
[333] From Beyrout, Damascus, the Mount of Olives, Anti-Libanus.
In the calcareous marls of the Upper Missouri river, extending nearly
to the Rocky Mountains, similar fossils are met with.
In the interior of Florida, the white orbitoidal limestone is traversed
by flint; and the calcareous and siliceous masses are full of
microscopic foraminifera.[334]
[334] Smithsonian Contributions, vol. ii. p. 161.
[Sidenote: FORAMINIFERA OF THE CARBONIFEROUS FORMATIONS.]
Foraminifera of the Carboniferous Formations.--In the carboniferous
limestones of England, the late Mr. Bowman, Prof. Tennant, and Mr.
Darker, detected shells of foraminifera, apparently of the genus
Fusulina.[335] Prof. Phillips mentions the occurrence of nautiloid
foraminifera in the palæozoic limestones of Carrington Park, South
Devon, and Yorkshire.[336]
[335] Edinburgh New Phil. Journal, vol. xxx. p. 44.
[336] Proceedings of the Polytechnic Society of the West Riding of
Yorkshire, 1845.
Dr. Dale Owen is said to have obtained "well characterized polythalamia
from the oolitic portion of the carboniferous (Pentremitic, _ante_,
p. 298,) limestone of Indiana."[337] And M. de Verneuil discovered a
species of Fusulina, in the Millstone-grit of the coal formation of the
Ohio.
[337] American Journal of Science, vol. xlvi. note to p. 311.
But the most remarkable deposits of foraminifera in the palæozoic
rocks, are those of Russia, described by Sir Roderick Murchison.[338]
The upper beds of the Mountain limestone in the Lower Volga, consist
of laminated calcareous shales, composed of an aggregation of shells
of Fusulinæ. Bands of limestone, through a vertical extent of two
hundred feet, are loaded with Fusulinæ; layers from five inches to five
feet in thickness, consist of a pure white Fusulina limestone; the
foraminifera are all of one species, the _Fusulina cylindrica_.
[338] Geology of Russia in Europe, vol. i. p. 86. pl. i. fig. 1.
Foraminiferous Limestone of New Zealand.--"On the eastern coast of
the Middle Island of New Zealand, to the north of Otago, strata
of yellow and fawn-coloured limestone appear on the surface at
Ototara, and continue to Kakaunui. This rock is generally friable and
porous; it contains terebratulæ, spines and cases of echinoderms,
pseudo-belemnites, teeth of sharks, &c. A microscopical examination
shows it to be in a great part composed of an aggregation of very small
polythalamia."[339] The specimens of the Ototara limestone received from
my son, are very rich in minute corals and shells, and foraminifera
of the European cretaceous type: species of Rotalia, Cristellaria,
Globigerina, Textularia, Rosalina, Nodosaria, Dentalina, &c. Among them
are two forms which occur at Charing: namely, _Rosalina Lorneiana_,
_Lign. 109, fig. 5_, and Textularia elongata: of the latter a
specimen in flint is figured, _Lign. 119, fig. 3_. The soft parts of
Rotaliæ are preserved in the Ototara limestone, as in our chalk.
[339] Notes on the Geological Structure of the Middle Island of New
Zealand, by Walter Mantell, Esq. of Wellington. 1848.
There are likewise, as at Charing, cases of Entomostracæ of the genera
_Basidia_ and _Cythereis_.[340]
[340] See Geol. Journal, vol. vi. p. 339. pl. xxix.
The assemblage of fossil remains in the Ototara rock has decidedly a
cretaceous aspect, but till the geological position of the strata in
relation to the other formations of the Island is determined, it would
be premature to regard these limestones as the equivalents in time of
the Chalk formations of Europe.[341]
[341] A list of the Ototaran fossils collected by Mr. Walter Mantell, is
given in Geol. Journal, vol. vi. p. 329.
Tertiary Foraminifera.--The marine tertiary deposits which contain
foraminifera in abundance, are so numerous, that it is unnecessary to
particularize any. The sands of the Paris basin in some localities are
so full of microscopic forms, that a cubic inch of the mass contains
sixty thousand. The friable calcareous strata at Grignon are a loose
aggregate of the shells of foraminifera and minute mollusks; and as the
fossil shells from that locality are very common, and generally filled
with debris, the student will have no difficulty in obtaining specimens
for examination. The tertiary argillaceous deposits of England are less
rich in foraminifera than the arenaceous; but the usual types occur in
the London Clay, at Highgate, Clapham Common, Bracklesham Bay, &c. The
Eocene marls of the United States are rich in foraminifera.
[Sidenote: FORAMINIFERA OF THE FENS.]
Foraminifera of the Fens of Lincolnshire and Cambridgeshire.--Though
the alluvial deposits of the fen-districts are comparatively of modern
date, yet the rich assemblage of foraminifera contained in the clay
of certain districts is so interesting and instructive, that a brief
notice of them must not be omitted. The foraminiferous character of
the Lincolnshire alluvium was first made known to me by specimens from
Bolton, sent me by Professor Williamson; and their extension over
a wide area in Cambridgeshire, by a liberal supply from Mr. Smith,
of March. The bed that abounds in these shells, is about seven feet
beneath the surface, and consists of a fine sea sand combined with
carbonaceous and argillaceous matter. By washing about a gallon of this
earth in water, an ounce of polythalamia and organic detritus may be
obtained. The perfect shells are as fresh as if just dredged up from
the sea; the soft parts--the membranous segments held together by their
tubular connexion--in many instances remaining in the shell; these
parts may be obtained by the solution of the shell in acid. When the
Rotaliæ are rendered transparent by immersion in Canada balsam, their
appearance, by transmitted light is identical with that exhibited by
the fossil specimens; and if viewed by reflected light, the body may
be seen occupying all the cells of the shell; but the segments are
somewhat collapsed; evidently from the shrinking of the animal tissues
after death.[342]
[342] Two specimens are figured in my notice of fossil Foraminifera.
Phil. Trans, p. iv. for 1846, pl. xxi. figs. 13, 14.
The organisms of the Lincolnshire alluvium have been thoroughly
investigated by Prof. Williamson; they comprise many species and
genera, of the usual types; as Rotaliæ, Rosalinæ, Polystomellæ,
Textulariæ, Lagenæ, Nodosariæ, &c. It is remarkable, that though a
marine estuary deposit, no vestiges of diatomaceæ have been observed.
The bed so rich in foraminifera, extends west and south-west of the
Wash. Mr. Smith sent me a mass of sandy clay, from a well sunk in the
town of March, to the depth of twenty-five feet, that was loaded with
these beautiful organisms.[343]
[343] The reader interested in these inquiries should peruse the highly
interesting Memoir by Prof. Williamson, "On some Microscopical Objects
found in the Mud of the Levant, and other Deposits." Manchester Phil.
Trans, vol. viii.
Recent Foraminiferous Deposit at Brighton.--An interesting fact
connected with the phenomena under review is deserving record. The
presence of the fossils of an older formation, in strata subsequently
deposited, and in part composed of the detritus of the rocks whence the
organic remains were derived, is not uncommon: such fossils are termed
by the French geologists "_fossiles remaniés_." The nature of these
re-deposited fossils is generally obvious; either by the water-worn
condition of shells, bones, &c. or from their containing particles of
their parent bed; or if casts, from their mineral composition. Thus
in the chalk of St. Catherine's Mount, near Rouen, there are numerous
casts of Ammonites, Scaphites, and other shells, composed of marl full
of particles of greensand. These have evidently been washed out of the
preceding cretaceous beds of firestone or glauconite; and re-deposited
in the chalk strata in which they are now imbedded.[344] * * * * *
[344] M. D'Orbigny.
Along the sea-shore, to the east of Brighton, there is a bank of
sand and calcareous mud, the detritus of the neighbouring cliffs,
in the progress of formation; and in this sediment Mr. Reginald
Mantell discovered recent Rotaliæ, Nodosariæ, &c., with frustules
of Bacillariæ, Coscinodisci, Naviculæ, and other diatomaceæ;
associated with cretaceous polythalamia washed out of the chalk,[345]
The difference in the aspect of the recent and fossil organisms
was so evident, as to leave no doubt of the correctness of this
interpretation. Here, then, at the present moment, a deposit is going
on, whose organic contents consist of an assemblage of species of
living animalcules of our seas, with the fossil forms of the ancient
chalk ocean; in like manner as in the bed of the Nile, the Nummulites
of the tertiary rocks are being imbedded with the existing mollusks and
desmidiæ of that river (_ante_, p. 345).
[345] See _ante_, p. 99.
[Sidenote: GEOLOGICAL DISTRIBUTION OF THE FORAMINIFERA.]
Geological distribution of the Foraminifera.--According to the
observations of M. D'Orbigny, the first appearance of the tribes of
minute beings which have played so important a part in the elaboration
of materials for the formation of the sedimentary rocks of the
secondary and tertiary ages, and are at this moment invisible but
powerful agents in the accumulation of calcareous sediments at the
bottom of the sea, was in the Carboniferous epoch, and by a single
type, the _Fusulina_ (_ante_, p. 346). I believe no certain evidence
of the occurrence of Foraminifera in Silurian or Devonian deposits has
been obtained.
M. D'Orbigny gives the following summary of the distribution of the
known fossil and recent species:--
GENERA. SPECIES.
Carboniferous System 1 1
Jurassic 5 20
Cretaceous 34 280
Tertiary 56 460
Living in the present Seas 68 1000
Of the recent species, 575 inhabit the Tropics.
------ 350 ----- Temperate zones.
------ 75 ----- Cold regions.
The above statistical view was published six years ago; but the great
activity of research that has since prevailed, has largely augmented
the known number both of fossil and recent forms. M. D'Orbigny's recent
Tables[346] give for the Jurassic or Oolite 10 genera; Cretaceous, 38
genera; Tertiary, 60 genera; but this estimate must be far too low.
[346] Cours Elémentaire de Paléontologie.
* * * * *
I have thus endeavoured to convey a general idea of the highly
important results obtained by the microscopical investigation of the
minute organisms that enter so largely into the composition of many of
the fossiliferous deposits.
Without the aid of the most perfect optical instruments which modern
science and art have produced, even the existence of many of these
structures could not have been demonstrated; and we cannot doubt, that
were the powers of the microscope increased, the fossil remains of
beings still more minute would be detected; and that rocks and strata
which now appear to consist of amorphous particles of lime, of silex,
and of iron, would prove to be the aggregated skeletons of animals,
yet more infinitesimal than those which have formed the subject of our
contemplations. How strikingly illustrative are these phenomena of the
profound remark of the illustrious Galileo--"_La nature fait beaucoup
avec peu, et ses opérations sont toutes également merveilleuses._"
INSTRUCTIONS FOR THE MICROSCOPICAL EXAMINATION OF CHALK, FLINT, AND
OTHER ROCKS.
[Sidenote: MICROSCOPICAL EXAMINATION OF CHALK.]
Chalk.--The following method is that recommended by M. Ehrenberg, Place
a drop of water upon a plate of thin glass, and put into it as much
scraped chalk as will cover the fine point of a knife, spreading it
out, and leaving it to rest a few seconds; then withdraw the finest
particles which are suspended in the water, together with most of the
liquid, and let the remainder become perfectly dry. Cover this dried
spot of chalk with Canada balsam (the turpentine of _Abies balsamea_),
and hold the plate of glass over the flame of a lamp, until the balsam
becomes slightly fluid, without froth or air-bubbles; it should be
maintained in this position (the glass being kept as hot as the finger
will bear) for a few minutes, until the balsam is found to have
thoroughly permeated the substance to be examined. It is preferable
to place a piece of very thin glass upon the balsam, and gently press
it down, and allow it to remain. The best flatted crown-glass should
be used for placing the chalk or other objects on. It is convenient
to have the slips of glass of one size, or the specimens will require
different boxes for their reception; three inches by one inch is that
usually employed. These objects require to be viewed with a power
magnifying three hundred times linear, that is, in diameter; and if the
process has been properly conducted, it will be seen that the chalk is
chiefly composed of well-preserved organisms. In these preparations
the cells of the foraminifera appear at first black, with a white
central spot; this is caused by the air contained in those cavities,
for air-bubbles always appear as black annular bodies; by degrees,
the balsam penetrates into all the single cells, the black rings
of the air vesicles disappear, and the structure of the original is
beautifully displayed.[347]
[347] Specimens of chalk, flint, and other rocks for examination; or
specimens prepared on slides, may be obtained of the microscopic
artists, named in the Appendix.
Soft part of Rotaliæ in chalk.--The manner in which I obtained the
unmineralized soft bodies of foraminifera from chalk has already
been mentioned (_ante_, p. 360); but it may be useful to offer a
few additional suggestions; for such fossil remains are not easily
extracted. Many experienced microscopical observers have not succeeded
in obtaining one good specimen; but others have been more fortunate, or
persevering.
In several glass test-tubes, (the more the greater chance of success,)
put a few grains of chalk powder: pour the tube half full of diluted
hydrochloric (muriatic) acid--about ten parts water to one of
acid--agitate, and set the mixture by: when all action has ceased add
one or two drops of undiluted acid to each tube, and repeat the process
at due intervals till all the calcareous matter is dissolved. Pour
off the fluid, substitute distilled water, agitate, and then let the
sediment subside. The residue will consist of atoms of quartz and other
insoluble mineral matter, and animal tissue, if there be any. Then,
with a camel-hair pencil, place a small portion of the sediment on a
glass slide, and when dry cover it with Canada balsam, and treat it as
above directed. Among a dozen slides thus mounted, there will probably
be two or more good examples of the body, or detached membranous
segments of Rotaliæ or Textulariæ, like those figured in _Lign. 118_.
Calcareous Sandstones and Marls.--These substances may be examined by
the same process; but if of loose texture, Dr. Bailey recommends that
some of the sandy powder should be spread very thinly on a plate of
glass, with or without water, and by the aid of a lens of moderate
power the roundish grains should be selected and picked up with fine
forceps, or the point of a needle, and transferred to another piece of
glass, having on one spot a thin coat of Canada balsam. This should
be gently heated over a spirit lamp, when the balsam will penetrate
the grains, and render them transparent; by this process the minutest
shells, &c. may be detected. For a hasty exploration, the dust may be
rendered sufficiently transparent by a drop or two of oil of turpentine.
Sandy calcareous marls may be examined by diffusing a few grains in
water in a wine-glass, the lighter portions will be suspended in the
fluid, and may be placed on glass, and when dry prepared with Canada
balsam in the usual manner.
[Sidenote: MICROSCOPICAL EXAMINATION OF FLINT.]
Flint.--Flint, and other siliceous stones, require to be chipped into
very thin fragments, and immersed in oil of turpentine. A clear,
translucent flint should be selected, from which fragments may be
shattered off by smart blows of a hammer, over a sheet of white paper:
the most transparent flakes are to be selected, and these should be put
in oil of turpentine, in a wide-mouth glass bottle. Take out the pieces
for examination with forceps, and inspect them as transparent objects,
by transmitted light. When good specimens are discovered, mount them in
Canada balsam.
It is hazardous to entrust such fossils to the lapidaries; an
interesting group of twenty spiniferites was reduced to ten, by one of
our best workmen, in whose hands it was placed for polishing, with the
view of rendering it more transparent.
CHAPTER XI.
FOSSIL TESTACEOUS MOLLUSCA, OR SHELLS.
[Illustration: Lign. 120. Fossil Oyster, from the Chalk.
_Kemptown, Brighton._]
On Fossil Mollusca.--Numerous as are the fossil remains of the various
types of animal organization which have already passed under review,
they are far exceeded in number and variety by those of the beings
whose mineralized relics we now propose to investigate. Although every
one is familiar with the external appearance of the shells cast up by
the waves on the shores of our island, and of those which, from their
varied colours and elegant forms, are preserved in the cottage of the
peasant, and in the mansion of the rich, but few persons are conversant
with the nature of the animals that secreted and were protected by
these beautiful and enduring structures. The organization even of the
oyster, mussel, whelk, &c., is known only to the naturalist. Appearing
to the uninstructed eye as a shapeless gelatinous mass, there is
nothing to arrest the attention, or excite the curiosity. Yet the
beings which inhabited these durable cases, are objects of the highest
interest and present a rich field of instructive investigation.
Except as shedding some light on the structure and economy of their
inhabitants, the shells, in the estimation of the naturalist, are
the least interesting part of the organization of the Mollusca; but
to the geologist, from their permanent nature, and the proofs they
yield of the conditions under which the strata that contain them were
deposited, they are important in the highest degree. It has even been
found convenient to classify formations, in which fossil shells largely
prevail, by the relative numerical proportion of the recent and extinct
species found in the different groups of strata; and the terms, Eocene,
Miocene, and Pliocene, (proposed by Sir C. Lyell,) have reference to
this character, as we have previously explained (_ante_, p. 24).
[Sidenote: FOSSIL MOLLUSCA.]
The _Mollusca_, a name indicative of the soft nature of the integuments
of these animals, constitute a very comprehensive subdivision of the
animal kingdom, and are separable into two principal groups, viz. the
_Acephala_ and the _Encephala_.
I. The Acephala (so termed because they are destitute of a head) have
neither jaws, tongue, nor a distinct mouth. They are aquatic, and
are subdivided into classes, according to the modification of their
integument, or of their gills.
_a._ The Tunicata (from the elastic _tunic_, or _mantle_, in which
they are enclosed) have no shell, and therefore do not come within
the scope of our inquiries: yet it is possible that the soft parts
even of these perishable structures may have left some trace, or that
markings of their integument on the silt or mud may be preserved;[348]
and I would recommend the student to search for such indications on the
rippled surface of clays and sandstones.
[348] The _Ischadites Königi_ of the Ludlow rock was supposed to
resemble _Boltenia_, a pedunculated Ascidian.
_b._ The Brachiopoda (_arm-feet_) have two long spiral fleshy arms,
or brachia, developed from the sides of the alimentary orifice, are
enclosed in bivalve shells, and respire by means of their vascular
skin, or mantle. They have not the power of locomotion, but are fixed
by a peduncle to other bodies.
_c._ The Lamellibranchia (_plated gills_) have also bivalve shells, but
their respiration is effected by gills composed of vascular membrane
disposed in plates, and attached to the mantle; the _beard_ of the
Oyster is the branchial or respiratory apparatus of that animal. These
bivalve Mollusca are subdivided into those which close their shells
by one adductor muscle, hence called _monomyaria_, as the Oyster;
and those which have two muscles, _dimyaria_, as the Cockle. As the
impressions left on the shells, by the attachment of these adductor
muscles, and by the margin of the mantle, are found as perfect in
the fossil as in the recent, they constitute important distinctive
characters.
Dr. Gray's definition of the respective parts of univalve and bivalve
shells is at once clear, concise, and natural, being conformable to the
structure of the body of the enclosed mollusk.
The _front_ of the shell is the part which covers the head of the
animal; the back of the shell is the part which covers the tail; the
left and right sides correspond with the same parts of the mollusk.
In univalves, the apex of the shelly cone whether it be simply conical
or spiral (except in Patella) is over the hinder part of the animal:
when the shell is placed on its mouth with the apex towards the
observer, the parts of the shell correspond with the position of the
person looking at it.
[Sidenote: FOSSIL BIVALVE SHELLS.]
[Illustration: Lign. 121. Illustration of Fossil Bivalve Shells; _nat._
Petricola Patagonica. _D'Orb._
Interior of right valve, and the same valve with the animal as seen on
the removal of the left valve.
_a._ Labial Palpi.
_b._ Mantle.
_c._ Margin of shell.
_d._ Branchiæ.
_e._ Anal siphon.
_f._ Branchial siphon.
_g._ Foot.
_h._ Retractor muscle of siphons.
_i._ Posterior adductor.
_j._ Anterior adductor.
_k._ Ligament.
_l._ Umbo.
_m._ Lunule.
_n._ Base, or ventral margin.
_o._ Anterior side.
_p._ Posterior side.
_q._ Pallial line.
(The length of the shell is estimated from _o_ to _p_, its breadth from
_l_ to _n_.) ]
In bivalves (_Lign. 121_) the ligament is always on the dorsal
surface of the animal, and the mouth in front of the apex or umbo
of the valves, before the ligament. A bivalve placed with the hinge
side uppermost and the ligament towards the observer is in the same
relative position as the person looking at it; viz. the head in front,
and the right and left valves in their natural relations. The length
of the shell is therefore from the front to the back of the animal:
the width or transverse diameter is from the umbo to the margin.
Much confusion has arisen from many conchologists having described
the length and width of a shell diametrically opposite to the proper
position of its inhabitant.
II. The Encephalous Mollusca.--These possess a head, with feelers or
soft tentacula, eyes, and a mouth with jaws; they are arranged in
classes, according to the modification of their locomotive organs; for,
with but few exceptions, they are free animals, and can crawl, climb,
or swim. Their shells are, for the most part, composed of one piece,
or valve, hence they are termed _Univalves_. In some genera the shell
is a simple cavity, spirally disposed, as in the Snail; in others, it
is conical, consisting of one or many pieces, as in the _Limpet_ and
_Chiton_. In the Cephalopoda it is internally divided into cells, or
chambers, as, for example, in the Nautilus.
The Encephalous Mollusca are subdivided into the following classes;
viz.--
_a._ Pteropoda (_wing-feet_).--In these the organs of progression are
two wing-like muscular expansions, proceeding from the sides of the
neck, by which they can swim and float in the open sea: all the species
are of small size.
_b._ Gasteropoda (_feet under the body_).--These crawl by means of a
muscular disk, or foot, which is attached to the under-part of the
body; most of the species are marine, but some are terrestrial, and
others inhabit fresh-water. They are very widely distributed; the
garden snail is a familiar instance of a terrestrial Gasteropod.
_c._ Cephalopoda (_feet around the head_).--The mollusca of this order
have powerful muscular arms, or tentacula, which surround the head,
or upper part of the body; some genera have no shell, but possess an
internal skeleton, as the recent Sepiadæ and the fossil Belemnitidæ.
Most of the testaceous Cephalopoda have a discoidal, univalve shell,
which is divided internally by septa or partitions; as the Nautilus.
[Sidenote: FOSSIL MOLLUSCA.]
In many univalves the aperture or opening is entire, that is, without
any notch or groove; in others it is notched or extended into a canal,
or siphon, and this character has relation to the respiratory organs:
thus the Gasteropods, in which the water is conducted to the interior
by a muscular tube, or siphon, have the margin of the aperture of the
shell channelled; as in the Whelk, or _Buccinum_. Many of the land
and fresh-water species have entire openings, and are, for the most
part, herbivorous; while the greater number of the marine univalves
have the aperture indented or notched, and are carnivorous.[349] Some
of these mollusca, too, have a retractile proboscis, armed with minute
teeth, by which they can rasp or bore into the shells of the species
on which they prey. There are some exceptions to the above rules,
but the prevalence of the characters specified afford pretty certain
indications of the fluviatile or marine nature of the originals.
The application of these data to geological investigations will be
considered hereafter.
[349] The form of the aperture does not necessarily indicate fresh-water
genera. _Melanopsis_, _Pirena_, and most of the _Melaniæ_ have a
channelled or notched aperture. Fresh-water univalves frequently have
the spire corroded; in a fossil state they can only be determined
[to be fresh-water species] by their analogy to recent genera and
sub-genera.--_Note by Mr. Woodward._
In the generic distinctions of the simple univalves, the form of
the mouth is an important character; while in the bivalves, the
configuration of the hinge affords an equally convenient aid for their
classification.
Some tribes of testaceous mollusca are exclusively marine; many are
restricted to the brackish water of estuaries; others live only in
fresh-water; and some on the land. Their geographical distribution is
alike various: certain groups inhabit deep water only, and are provided
with means by which they can maintain themselves near the surface of
the ocean, far away from any shore; while others are littoral, that is,
live in the shallows along the sea-shores. Many exist in quiet, others
in turbulent waters; some are gregarious, like the oyster; while others
occur singly, or in groups. The vertical range, that is, the relative
depths in which the mollusca live in the sea, is also strictly defined;
certain genera being, in a great measure, restricted to moderate
depths, others to a few fathoms, and many to the profound abysses of
the ocean, which neither the dredge nor the plummet can reach. All
these varieties of condition are more or less strongly impressed on
the shells, which may be considered as external skeletons;[350] and
the accomplished conchologist is enabled, by certain characters, to
determine the nature of the animals which inhabited them, and the
physical conditions in which they were placed.[351]
[350] In equivalve bivalves the animal lives in an upright position. In
inequivalves, _i.e._ one large and one small valve, the animal lies on
its side. The situation of bivalve shells, as oysters, should therefore
be noticed, for if they lie on their concave shell, with the flat valve
uppermost, it is evident they were overwhelmed in their native bed and
in a living state; if they lie indiscriminately on either valve, they
were probably dead shells and overwhelmed in that state. If the pallial
imprint is notched by a sinus, it shows the presence and size of the
tubes of the mantle. Whether there be one or two muscular impressions
is of far less importance.
[351] For an extended notice of the geographical distribution of
testacea, see Prof. Edward Forbes, British Marine Zoology, Part I. p.
141.
The number of living species of mollusca known to naturalists, not
including the shell-less genera, exceeds twelve thousand; and almost
every day is adding new species, for scarcely a vessel arrives from
distant seas without enriching the stores of the conchologist. The
numerous genera into which they are divided by systematists, and the
constant changes effected in arrangement and nomenclature by every
writer on the subject, render it difficult if not impossible to present
the reader with any satisfactory epitome of modern conchology.
I must restrict myself to a brief account of some of the most
common genera that occur in the British strata; and shall dwell
more particularly on those species which prevail in the secondary
formations, because they present the most important deviations from
the recent types that are familiar to the general observer; by this
means, and by reference to figures in standard works, the collector
will, I trust, be enabled to identify the fossil shells which may
most frequently come under his notice in the course of his geological
rambles.
FOSSIL BIVALVE SHELLS; INCLUDING THE BRACHIOPODA AND LAMELLIBRANCHIA.
[Sidenote: FOSSIL BIVALVE SHELLS.]
Although in the modern Tertiary strata, as the Crag, and in the
arenaceous beds of the Eocene formations, shells are generally found
in so perfect a state, that no caution or knowledge is requisite for
their collection, yet a few preliminary remarks are necessary to point
out certain conditions in which the remains of mollusca, or evidence of
their existence, occur in the mineral kingdom, and particularly in the
older fossiliferous rocks. Shells are found in the strata in the three
following states:--
1stly. Shells in which the constituent substance has undergone but
little change. Many of the specimens in the sands of the Crag in
Norfolk and Suffolk, and in the Eocene beds at Grignon, near Paris,
and the Pliocene of Palermo, in Sicily, are as perfect as if collected
from the sea-shore, having suffered no loss but that of colour. In
some instances, even the varied markings on the surface remain; but in
general the shells are bleached, or have a ferruginous stain.
2dly. The form preserved, but the constituent substance mineralized.
This state is very common in shells that are imbedded in hard rock,
whatever may be the age of the deposit. In calcareous strata the
testaceous substance is generally transmuted into calcareous spar, as
in most of the specimens from the chalk, oolite, mountain limestone,
&c. In sands abounding in silex, the shell is changed into flint, as
in the exquisite fossils from the Greensand of Blackdown, Devonshire;
in deposits permeated with sulphuret of iron, the shells are often
metamorphosed into pyrites, as in the Ammonites in the Lias, Galt, &c.
3dly, In the state of casts and impressions. Although in loose sand
the shells are either empty, or filled with detritus easily removable
by washing; in clay, limestone, and sandstone, the cavities are
generally occupied by consolidated materials, which had entered when in
a soft or fluid state; and frequently the substance of the shell has
disappeared, and the stony cast of the interior alone remains. In many
instances, the spaces left by the dissolution of the shells are filled
with spar, or the casts are closely invested by the surrounding stone,
from long-continued superincumbent pressure while the matrix was in
a plastic state; and in such cases the casts are often distorted and
flattened. But the vacancy is occasionally empty, and on its walls is
found an impress of the external surface of the shell, with all the
lines and ornaments of the original as sharp as if cast in plaster of
Paris.
[Illustration: Lign. 122. Turritellæ, from Bracklesham, Sussex. _Tert._
Fig. 1.--Turritella conoidea; the perfect shell: _nat._
2.--Septarium, with Turritellæ; a polished slab: 1/3 _nat._
3.--A cast of one of the shells, in calcareous spar: _nat._
]
[Sidenote: SEPTARIUM WITH SHELLS.]
The specimen, _Lign. 122, fig. 2_, from the tertiary strata at
Bracklesham Bay, Sussex, is a polished slice of indurated argillaceous
limestone, from a septarium (_nodule divided by fissures_), abounding
in spiral univalve shells, called _Turritellæ_. _Fig. 1_ is a perfect
shell of the same species, extracted from soft clay; and _fig. 3_, a
cast in calcareous spar, obtained from the septarium. In the polished
slab, _fig. 2_, sections of numerous shells are seen. The dark
partitions, or septa, are veins of spar, which occupy interstices
that have been formed in the clay-nodule by shrinking; and if the
specimen be closely examined, the shells will be found split across and
displaced by the fissures; thus presenting an interesting illustration
of the faults, or dislocations, of the strata, so familiar to the
geological observer. In the present instance, the lines on the exterior
of the shell do not materially differ from those on the interior, and,
consequently, the cast, _fig. 3_, and the shell. _fig. 1_, resemble
each other; but in many species there is a striking contrast between
the outer and inner surfaces, the external aspect being strongly
ornamented, while the internal is smooth; the cast, therefore, in
such examples, so little resembles the shell, that an inexperienced
collector may readily suppose it belongs to a different species. The
bivalve called Trigonia, _Lign. 127, figs. 1, 2_, is an instance of
this contrast.
The polished slab of the Septarium, _Lign. 122, fig. 2_, demonstrates
another condition of fossil shells--that of a compact argillaceous
limestone--and entire beds of marble are composed of an aggregation
of this kind, formed of shells and other animal exuviæ, consolidated
by mineral infiltrations. In the older secondary strata this state
prevails; and the beautiful markings of many valuable marbles, are
merely sections of the enclosed shells. But this process is not
restricted to the deposits of ancient date; at the present moment
the same operation is silently but constantly going on in our seas,
and an examination of the specimen, _Lign. 123_, will afford an
exemplification of the manner in which these shelly limestones are
produced.
[Sidenote: BRIGHTON SHELL-CONGLOMERATE.]
[Illustration: Lign. 123. Shell-Conglomerate; now forming in the
British Channel.
_Dredged off Brighton._
Fig. 1.--An Aggregation of Shells and Corals; the interstices are
filled up with sand, and the mass is consolidated by an
infiltration of carbonate of lime.
2.--Trochus ziziphinus; extricated from the mass with the
following:
3.--Pecten opercularis.
4.--Serpula.
5.--Portion of a Cellepora; magnified.
6.--Sabella.
]
We have here a solid mass of stone, composed of several recent species
of shells, corals, &c. It is a fragment of a large block, dredged
up from the British Channel, off Brighton. Similar masses have been
obtained at different soundings along this part of the Sussex coast;
and in some specimens numerous other species of recent shells, as
oysters, mussels, whelks, &c. enter into the composition of the
consolidated rock. The shelly and coralline limestones and sandstones,
so abundant in the ancient strata of England have been formed in a
similar manner; and when the modern conglomerate of Brighton shall have
been permeated with crystalline matter, and subjected to great pressure
by superincumbent deposits, through countless centuries, and at length
be elevated above the waters, it will constitute beds of shell-marble,
in some mountain range, and become an interesting, perhaps the only
memento, of the races of mollusca and polypiaria of the present seas,
when all record and traces of Great Britain and its inhabitants shall
be destroyed.
[Illustration: Lign. 124. Shell-Limestone; from the mouth of the Thames.
Fig 1.--A mass of Cockle-shells and Whelks, consolidated into a
coarse limestone.
2, 4.--One of the shells, Cardium edule, extracted from the
block.
3.--A slice of the rock, polished, the markings on the surface
being derived from sections of the shells.
]
[Sidenote: MODERN SHELL-LIMESTONE.]
Off the Kentish coast, near the mouth of the Thames, a bank of
consolidated shells, chiefly of one species, is in the progress
of formation, from which blocks may be obtained of great firmness
and solidity (_Lign. 124_); these, when cut and polished (_fig._ 3),
display a variety of markings, produced by the sections of the shells.
Extensive shoals of loose shells, composed almost wholly of the
_Cardium edule_, exist in several localities, near the embouchure
of the Thames; and these are continually shifting with the changes
of the wind and tide; it is only in a few places that consolidated
blocks occur, like that of which a fragment is figured in _Lign. 124_.
These examples of shelly limestones and sandstones now in progress of
formation will familiarize the student with the nature and origin of
those ancient deposits of a similar character, which contain extinct
species and genera of mollusca.
"The vast deposits of fluviatile shells which exist in Florida, at
Picolata, Volusia, and Enterprize are of great geological interest.
The two latter places present bluffs and hills of from forty to fifty
feet in height, extending half a mile or more from the river, that are
composed of scarcely anything but well-preserved shells of _Paludina
vivipara_, _Ampullaria depressa_, some undetermined species of _Unio_,
_Helix septemvolvis_, _Melania_, and a few others. There is but a
scanty mixture of earth, and the shells are clean, and look as if
they had been washed ashore after the death of their inhabitants. In
some places the beds are sandy, and are hardening into a calcareous
shelly sandstone. In one such bed the superficial stratum furnished
a few bones of turtles and undetermined fragments, the bones of some
large vertebrate animal. This is, I believe, the locality where
Count Pourtalés collected human bones in a recent sandstone.... No
microscopical forms were detected in these beds after the most careful
search."[352]
[352] Dr. J, W. Bailey, in Smithsonian Contributions, vol. ii. Article
viii. p. 23.
[Illustration: Lign. 125. Terebratula and Rhynchonella; _nat._
_Chalk. Lewes._
Fig. 1.--Rhynchonella plicatilis.
1_a_.--The same species, partly open.
2.--Rhynchonella subplicata.
2_a_.--Front view of the same.
3.--Terebratula semiglobosa; side view.
3_a_.--The same species, seen from above.
4.--Terebratula subrotunda.
]
Fossil Shells of the Brachiopodous Mollusca.--These are bivalve shells,
of which nearly five hundred species are found in the British strata.
They occur in incredible numbers in the ancient rocks, to which several
genera are restricted; while some continue through all the formations,
and inhabit the present seas; but the existing genera are few.
[Sidenote: TEREBRATULA.]
Terebratula (_bored, alluding to the perforated beak_), _Lign.
125._--The common species of this genus must be familiar to all who
have ever looked into a quarry of Chalk, or of Shanklin sand, in the
south-east of England. They have been humorously called the _Fossil
Aristocracy_, from the incalculable antiquity of their lineage.
The species are very numerous; more than 300 extinct forms have been
determined.[353] Those figured in _Lign. 125_ are from the White Chalk,
and are beautifully preserved; even vestiges of the colour occasionally
remain. In a living state, the animal is fixed to foreign bodies by a
byssus, or peduncle, which passes through the opening in the beak, or
arched extremity, of the shells,[354] The most interesting circumstance
relating to these mollusca, is the respiratory apparatus, which
consists of two long ciliated tubes, spirally coiled, united at their
base, and supported by slender calcareous processes, which are often
preserved in the fossils. Thus, in specimens from the soft chalk, the
calcareous earth may be removed from the interior of the shell, and
the appendages exposed, as in the examples, _Lign. 126, figs. 1, 2_;
and in the shells that are empty, these processes occasionally remain
distinct, or are coated by a thin pellicle of calcareous spar, or
pyrites.
[353] See Catalogue of _Terebratulidæ_, published for the British Museum.
[354] In the British Museum (Eastern Zoological Gallery, case table A)
there are between thirty and forty recent terebratulæ (_T. australis_,
Quoy, a plaited species, much resembling _T. fimbria_ of the Inf.
Oolite, Cheltenham) attached with their byssi to a block of stone, from
Port Jackson, where it was found by Mr. Jukes just below low-water.
In the smooth _Terebratulæ_, the laminations of the shell are full of
minute perforations, which may be seen by a lens of moderate power; the
appearance of this structure, when highly magnified, is shown _fig._
2a, _Lign. 126_.[355] The Rhynchonellæ (as _Lign. 125, figs. 1, 2_,)
do not possess this organization.
[355] An interesting Memoir on the Microscopal Examination of Shells has
recently been communicated to the Royal Society by Dr. Carpenter.
Several species of Terebratula are found both living and fossil,
_e.g._ _Terebratula vitrea_, living in the Mediterranean, fossil in
Sicily,--_T. caput-serpentis_, recent in the British seas, fossil in
the Crag,--and _T. lenticularis_, both recent and fossil in New Zealand.
[Illustration: Lign. 126. Terebratula and Spirifer.
Fig. 1 and 2.--Upper and under valve of Terebratula carnea.
_Chalk; Lewes_: _a_, _a_, remains of the calcareous support of
the _brachia_.
2_a_.--Portion of the shell of _Terebratula carnea_, magnified to
exhibit the perforations.
3.--Spirifer trigonalis, with part of the upper valve removed,
to show one of the spiral processes. (_Min. Conch._)
_Mountain Limestone._
]
[Sidenote: SPIRIFER. PENTAMERUS.]
Spirifer (_containing spiral processes_). _Lign. 126._--In the
Silurian, Devonian, and Carboniferous limestones there is a profusion
of several genera of _Brachiopoda_, whose peculiar forms render
them easily recognisable. Among these, the Spirifers are the most
interesting, on account of their spiral calcareous processes, which
in the recent state supported the ciliated _brachia_, being often
preserved. A specimen, in which part of the upper valve of the shell
has been removed, and one of the spires exposed, is figured _Lign.
126, fig. 3_. (_Wond._ pp. 735, 736).[356]
[356] See a Memoir on the Anatomy of the Brachiopoda, by Professor Owen.
Zoological Trans, vol. i. p. 145, _et seq._
All these genera are extinct; they prevail in the oldest fossiliferous
rocks, and gradually disappear as we ascend to the newer formations;
the last trace of their existence is in the Lias, in which one species
has been found. But the _Terebratulæ_ abound in the Lias, Oolite,
Chalk, &c., occur in the tertiary formations, and several living
species inhabit the seas around Australia and New Zealand. (See _ante_
p. 390.)
Rhynchonella, _Fischer_. The "_plaited_" _Terebratulæ_ differ from the
typical species (_e.g._ _T. australis_, caput-serpentis, vitrea, &c.)
more than even the Spirifers differ, and must be regarded as forming
a distinct _family_, Rhynchonellidæ, which will include _Pentamerus_.
The shell is not punctate; the arms are spiral, supported only at their
origins by shelly processes; the larger valve is _beaked_ acutely,
and has a notch within the beak through which the pedicle passes;
sometimes the notch is converted into a foramen, by two little plates,
(_deltidium_,) as in _Terebratula_. The form of the Rhynchonellæ is
tetrahedral. _Lign. 125_.
Pentamerus, _Ly._ p. 352.--With the Spirifers, and other Brachiopoda
of the Silurian System, some bivalves which, in their general figure,
resemble certain species of Terebratulæ, frequently occur. These shells
differ in their internal structure from all other genera, in having a
septum, or plate, by which their cavity is divided into four chambers;
and in one valve the septum itself contains a cell, thus making five
chambers, whence the name _Pentamerus_ (_five-celled_). The casts of
these shells often have fissures, produced by the decomposition of
the septa; and occasionally these cavities are occupied by calcareous
spar. Specimens of this kind commonly split into two parts, in one of
which two, and in the other three, chambers may be detected; the fifth
chamber is the canal of the peduncle. Four species are known, and all
belong to the Silurian rocks.
Orthis, Leptæna, and Producta form a third family, with horizontal
spiral arms, unsupported by shelly processes. _Davidsonia_ is a Leptæna
_attached_ by the ventral valve, and the only genus in this family
which is fixed by _the shell itself_.
Calceola. a genus of Brachiopoda; the shell of an inverted pyramidal
form, the upper valve nearly flat; found in the Devonian strata of the
Eifel, and in Devonshire.
Crania, _Ly._ _fig._ 205. These are small brachiopodous shells,
attached to other bodies; very frequently to the Echinites of the
chalk. The free valve is commonly wanting, but I have found specimens
dispersed in the rock. In many of the quarries in Kent and Sussex, the
helmet Echinites bear groups of these shells. _Ly. _fig._ 13._
Orbicula. This genus resembles Crania in form, the upper valve being
like a limpet, whilst the attached valve is flat; it differs, however,
from Crania in being horny and flexible, and is fixed to rocks on the
bed of the sea, by a muscular pedicle passing out through a small
fissure.
Species of Orbicula are found in strata of all ages, from the Lower
Silurian to the Tertiary, and several are now living in tropical seas.
Obolus. _Eichwald._ In the Lower Silurian (_Obolite grit_) of Sweden
and Russia, is a Lingula, with a hinge and a notch for the pedicle; it
has not hitherto been found in Britain.
[Sidenote: LINGULA. HIPPURITES.]
Lingula. _Ly._ p. 353, _fig._ 412.--The Brachiopoda referred to this
genus have a long peduncle, and their respiratory apparatus has no
calcareous support; the recent species burrow in the sand, being
usually inhabitants of shallow waters. The _Lingulæ_ aære readily
distinguished from the Terebratulæ by their imperforate, equivalved
shells. One species is found in the Aymestry limestone, and several
have been collected from the Mountain limestone, Oolite, and Shanklin
sand.
* * * * *
With reference to the species of Brachiopoda, particularly of the
Terebratulæ, which inhabit the depths of the ocean, Professor Owen
observes, that "both the respiration and nutrition of animals, which
exist beneath a pressure of from sixty to ninety fathoms of sea-water,
are subjects suggestive of interesting reflections, and lead us to
contemplate with less surprise the great strength and complexity of
some of the minutest parts of the frame of these diminutive creatures.
In the unbroken stillness which pervades those abysses, the existence
of these animals must depend on their power of exciting a perpetual
current around them, in order to dissipate the water laden with their
effete particles, and to bring within the reach of their prehensile
organs the animalcules adapted for their sustenance."
Hippurites. This genus belongs to a group of fossil shells whose
characters are somewhat problematical, some conchologists referring
them to the ordinary bivalves, and others to the Brachiopoda. Although
_Hippurites_ have not been discovered in the British strata, I am
induced to notice them in this place, in consequence of their great
abundance in the Cretaceous deposits of the South of France, and in the
Oolite of the Pyrenees; and also to illustrate the nature of a nearly
related genus, _Sphærulites_, of which one or more species occur in the
Sussex Chalk.
The Hippurite is of an elongated conical form, and fixed by its
base; it has internally a deep lateral channel, formed by two obtuse
longitudinal ridges. The base is sometimes partitioned off by
transverse septa, forming cells or cavities, as in the Euomphalus. The
aperture, or opening, is closed by an operculum, or upper valve. The
substance of the shell is cellular, and very thick, and when fractured
much resembles that of the lamelliferous corals: the laminæ are
sometimes separated into cells, or cavities, like the Spondyli. These
shells often attain considerable magnitude, and in certain districts of
the Pyrenees, where they abound, are called "_petrified horns_" by the
inhabitants. It is remarkable, that, while in the Chalk of the South of
France, Spain, Portugal, and Greece shells of this genus so prevail, as
to be considered the characteristic fossils of the formation, in the
North of France they are very rare, and in England have not hitherto
been discovered.[357]
[357] As marking the rapid progress of Palæontology in this country,
it may be noticed that the _only fossil_ figured in the first edition
of the Enclycopædia Britannica, in illustration of the article,
"_Petrifaction_," is one of these supposed petrified horns, described
by the Abbé Fortis.
* * * * *
Fossil Shells of the Lamellibranchia.--These are bivalve shells, the
animals of which differ from the preceding class, as we have already
stated, in performing respiration by means of lamellated gills. The
valves are united by a strong substance, termed the ligament, which,
by its elasticity, admits of the shells being opened to a considerable
extent; and they are closed by powerful, short, thick muscles, called
adductors. The shells of some of the genera, as the Oyster and Scallop,
have but one muscle, (_monomyaria_); others, as the Cockle, or Cardium,
and Venus, have two, (_dimyaria_); and by these characters the class is
arranged in two groups.
Monomyaria: _Bivalve Shells, with one muscular impression_.
[Sidenote: FOSSIL OYSTERS.]
Ostrea, _Lign. 120._--The Oyster is well known to possess no power of
locomotion; it is attached to rocks, pebbles, and other bodies, and
forms extensive beds, consisting of numerous individuals, of all sizes.
There are many fossil species; the British strata yield between forty
and fifty. In some localities. Oysters are found in thick beds, of
great extent, apparently on the spots they occupied when living. One
of the most interesting localities I am acquainted with, is Sundridge
Park, near Bromley, in Kent, where a hard conglomerate, entirely made
up of oyster-shells, and the shingle that formed their native bed,
is quarried. This stone is much employed for ornamental rock-work,
and several walls in and near Bromley are constructed of it: these
display the fossils, some with the valves closed, others open, others
detached, and the whole grouped as if artificially imbedded to expose
the characters of the shells. These oyster-beds belong to the tertiary
strata of the London basin; they extend to Plumstead, and other places
in the vicinity; and in some localities, the oysters are associated
with other bivalves, called _Pectunculi_. In the tertiary clays near
Woolwich and Bexley, fossil oyster-shells abound. In the neighbourhood
of Reading, in Berkshire, an extensive layer of fossil oysters occupies
the same geological position, namely, the lowermost sands and clays
of the London basin. Wherever the strata around London are perforated
to a sufficient depth, this oyster-bed is reached. Very recently an
Artesian well was bored at Hanwell, in Middlesex, and at the depth of
two hundred and eighty feet this stratum of sand with oyster-shells was
found. At Headley, near Reigate, in Surrey, there is a similar deposit.
These oysters very closely resemble the edible species.
The White Chalk contains several species of Ostrea, but I believe no
beds of these shells have been found in it; on the contrary, the
shells are diffused promiscuously through the strata. I have collected
a few groups of from thirty to forty shells, evidently the young or
fry of the species (_O. semiplana_) figured _Lign. 120_. This specimen
is an interesting example of the petrifactive process which the
mollusca have occasionally undergone; the soft parts of the oyster
are transmuted into flint, and the shell is changed into carbonate of
lime, having a crystalline structure. Both valves were perfect when
discovered, but I chiselled off the greater part of one shell to expose
the silicified body of the animal.
A small oyster, called _Ostrea vesicularis_, is a characteristic shell
of the chalk; one valve is convex, the other flat; it is abundant in
the Chalk of Norfolk, and also in the Firestone of some localities:
it is figured _Ly._ p. 212. Another small species, having the margin
plicated (_O. plicata_), is also frequent in the Chalk. A large shell,
with the margins deeply indented by angular folds, resembling the
recent cockscomb oyster, is abundant in the Chalk Marl and Firestone;
particularly near Dover, and around Selbourne in Hampshire, where
it attracted the notice of White, by its resemblance to the living
"Cockscomb Oyster" of the West Indies; it is named _Ostrea carinata_,
and figured _Ly._ p. 212, _fig._ 204. One other species may be noticed,
the Ostrea deltoidea, which has been found in every locality of the
Kimmeridge Clay in England and France. It is a very flat species, and
of a triangular form; the specific name is derived from a supposed
resemblance to the Greek letter Δ, _delta_. I believe that in England
no shells of this genus have been observed in strata older than the
Lias.
[Illustration: Lign. 127. Shells and Echinite from the Oolite and Lias.
Fig. 1.--Trigonia clavellata. Oxford Cloy, _near Weymouth_.
2.--Trigonia gibbosa; a limestone cast. _Isle of Portland._
3.--Cidaris Blumenbachii. _Oolite._ _Calne, Wilts._
4.--Trigonia costata. _Oolite._ _Highworth, Wilts._
5.--Spine of the Cidaris Blumenbachii.
6.--Gryphya incurva. Lias. _Cheltenham_.
7.--Ammonites Walcotii. Lias, _near Bath_.
]
[Sidenote: GRYPHYÆA.]
Gryphya. _Lign. 127, _fig._ 6._--The shells to which the term
_Gryphæa_, or _Gryphites_, is applied, are related to the Oyster, but
distinguished by the deep concave under valve, and its curved summit,
or beak, and the almost flat, or opercular upper shell. The Gryphites
are of a finer laminated structure than the oysters, and the ligament
of the hinge is inserted in an elongated curved groove. There are
about thirty British fossil species, none of which have been noticed
below the Lias, in which formation one very remarkable species is so
abundant as to be considered characteristic of the Liassic deposits. It
is so faithfully represented, _Lign. 127, _fig._ 6_, that description
is unnecessary. In the upper argillaceous beds of the Oolite and
Kimmeridge Clay, a very small gryphite, (_G. virgula_, _Ly._ p. 260_)
is so abundant, that it constitutes entire layers. The low cliffs on
the west of Boulogne harbour, like those near Weymouth, are composed
of this clay, and myriads of the gryphites are scattered on the shore,
with other shells of the same deposits; these shelly beds are called
_marnes à gryphées_, by the French geologists. A very large gryphite,
_Gryphæa sinuata_, (_Min. Conch._ tab. 336,) is found in the Shanklin
sand of the Isle of Wight, and of Kent and Sussex. At low water, in the
sand along the shore under Dunnose Cliff, near Shanklin Chine, numerous
specimens are always obtainable.[358]
[358] The name _Exogyra_ was applied to the Chama-shaped species of
Gryphæa by the late Mr. Sowerby, and other writers; but subsequent
authors have included these shells in the present genus.
[Sidenote: SPONDYLUS. PLAGIOSTOMA.]
Spondylus. _Lign. 128._--A species of this genus is so frequent in the
Chalk, that it ranks with certain Terebratulæ, as characteristic of
that formation. One valve is covered with long slender spines, which,
in the usual examples, are destroyed by the mode of extracting them.
The specimen figured shows the appearance of a shell partly cleared;
the remainder of the chalk might be removed by a penknife (taking
care to leave the longest spines supported by brackets of chalk), and
it would then resemble the beautiful fossils figured _Min. Conch._
tab. 78, and in _Geol. S. E._ p. 125. Between the beaks there is a
triangular aperture in the spinous valve, which some naturalists, with
much probability, suppose was once filled up with shell, as in the
recent species.
[Illustration: Lign. 128. Spondylus spinosus. _In Chalk-flint. Lewes._]
In the cretaceous strata of North America, Dr. Morton has discovered
a Spondylus (_S. dumosus_) very nearly related to _S. spinosus_;
but it differs in its general form, and has both valves beset with
strong spines. I have the fragment of a large bivalve from the Kentish
Rag (Mr. Bensted's quarry), which has the peculiar structure of the
Water-clam (_Spondylus varius_ of Mr. Broderip); namely, hollow
interspaces formed by shelly layers or partitions, which were secreted
by the posterior part of the mantle, or investing integument of the
animal, as it gradually receded from that part of the shell. In the
recent Water-clam the cells are full of fluid.[359]
[359] S
ee Penny Cyclop. Art, _Spondylidæ_.
Plagiostoma, Llhwyd, 1699. This genus, adopted by Mr. Sowerby in
the Mineral Conchology, is scarcely distinguishable from _Lima_ of
Bruguiere (1791). Most of the recent species are ornamented with small
asperities, from which the name _lima_ (file) is derived; they are
symmetrical shells attached by a byssus.
Several smooth species of this genus are found in the Chalk,[360]
Oolite, and Lias. A very large species (_P. giganteum_), sometimes ten
inches in diameter, abounds in the Lias (_Ly._ p. 274). It is somewhat
depressed in form, with the surface slightly striated; each valve has a
pointed beak, with two lateral expansions, or ears, as they are termed
by conchologists.
[360] See Foss. South Downs,, plate xxvi.
Plicatula, is another genus of this family, of which there are three
British fossil species. A delicate shell, with slender depressed spines
(_P. inflata_. _Foss. South D._ pl. xxvi.), occurs in the Chalk Marl.
The recent species are natives of the seas of warm climates.
Pecten.--The common scallop-shell will serve as a type of this genus.
The animals of these shells, unlike the oysters, have the power of
locomotion, and when in the water, may be seen moving with rapidity,
and flapping their shells to and fro with great activity. Numerous
species are found fossil. In the Pliocene, and other marine tertiary
deposits, Pectens abound; in the White Chalk there are several elegant
forms (see _Foss. South D._ plate xxv.); many kinds in the Oolite and
Lias; and several in the Devonian strata.
A large Mediterranean species (_Pecten Jacobæus_, _Ly._ p. 152)
occurs in the Pliocene strata of Palermo, in every stage of growth,
and as perfect as if recent. The Chalk and Shanklin sand contain a
small inequivalved Pecten, the lower valve of which is convex, and
pentangular, the upper flat, and both strongly ribbed, or pectinated;
it is named _Pecten quinquecostatus_ (_Foss. South D._ pl. xxvi. _Ly._
p. 212); and in the cretaceous strata of North America a variety of
this species is found.
In the Chalk Marl a large and beautiful Pecten (_P. Beaveri. Min.
Conch._ tab. 158) is very common, and I have obtained from Hamsey and
Southerham examples in the most perfect state of preservation; it is
a characteristic shell of the Chalk Marl of England (_Foss. South D._
plate XXV. fig. 11).
[Illustration: Lign. 129 Inoceramus Cuvieri. _Chalk. Lewes._
Fig. 1.--Beak and hinge of an Inoceramus.
_a._ The hinge line.
2.--Two valves of I. Cuvieri, displaced, and both
showing the external surface.
]
[Sidenote: INOCERAMUS.]
Inoceramus. _Lign. 129._--This name, which refers to the fibrous
structure of the shell, has been given to a fossil genus, of which
there are about thirty species in the cretaceous and oolitic
formations; and very recently four or five species have been discovered
in the Silurian strata of Ireland.[361] These shells are chiefly
characterized by their hinge (see _Lign. 129, fig. 1a._), and by
the fibrous structure of their constituent substance, which closely
resembles that of the recent _Pinna_;[362] and under the microscope is
found, like that shell, to consist of prismatic cells, filled with
carbonate of lime.[363] The species vary in size from an inch to three
or four feet in diameter. The shell, in consequence of the vertical
arrangement of the fibres, readily breaks to pieces, and it is often
extremely difficult to extricate a specimen with the hinge and beaks
tolerably entire. That they were equally brittle when recent is evident
from the numerous fragments diffused through the chalk and flint, and
occasionally imbedded in pyrites.[364] The form of the hinge is shown
in _Lign. 129, fig. 1_: in the lower specimen two valves of the same
individual are seen displaced, one lying over the other. The usual
chalk species are figured _Foss. South D._ pl. xxvii. and in _Min.
Conch._
[361] The term Inoceramus is restricted by the French geologists to the
beaked and laminated species of the Galt; and the chalk Inocerami are
arranged under the name _Catillus_.
[362] _Perna_ and all the Aviculidæ have the same structure, Inoceramus
scarcely differs from Perna.
[363] Dr. Carpenter on the Microscopical Structure of Shells. To detect
this structure, the shell should be immersed in diluted hydrochloric
acid, and when partially dissolved, the cells will be apparent.
[364] It was many years before I succeeded in obtaining a specimen with
the hinge perfect; and M. Brongniart, unable to obtain one from the
chalk of France, gave the figure of this genus from my Foss. South D.
pl. xxvii. in the Géog. Min. Env. de Paris.
In the Galt, or Folkstone-marl, two small species of this genus are to
be found in every locality I have visited. They were first figured and
described by Mr. Parkinson, under the name of _Inoceramus sulcatus_,
and _I. concentricus_ (_Wond._ p. 330, fig. 1 and 3). In most examples
the shell is in the state of a white, friable earth, and readily
decomposes, leaving patches of iridescent nacre on the casts; but I
have seen examples which prove that the originals were of a fibrous
structure, like the Inocerami of the Chalk.
[Illustration: Lign. 130. Flint, with fragments of Inoceramus.
_Chalk. Lewes._
_a._ Marks the section of a fragment of shell, with numerous cavities,
occasioned by the depredations of Cliona Conybearei.
_b._ Portion of shell partially decomposed, and exposing siliceous,
globular bodies, connected by filaments, which are flint casts of
the hollows left by the Cliona.
]
The shells of the Inocerami, like those of the oyster, and other living
mollusca, were exposed to the attacks of some parasite, and perhaps of
some Annelid, as the _Nereis_. The shells are often cellular from this
cause, and the cavities are found either hollow, or filled with chalk,
or, as in the example _Lign. 130_, with flint. In the latter case, upon
the decomposition of the shell, the siliceous casts remain in relief on
the surface of the flint, as in _Lign. 130, b_. Such specimens are
common in the broken flints of the South Downs, and in the shingle on
the sea-shore of chalk districts; and their origin would be difficult
to understand without this explanation.[365]
[365] The Rev. W. Conybeare first ascertained the origin of these
fossils, and figured and described them in an elegant Memoir, published
in Geol. Trans, vol. ii. first series. Mr. Morris proposes the name of
_Clionites_ for the fossil bodies derived from the depredations of the
Cliona on the Inocerami and other shells. See Annals Nat. Hist. 1851,
and my Pictorial Atlas of Organic Remains.
Avicula. _Lyell_, p. 274.--Above fifty species of this genus of shells
have been found in the British strata; their general character will
be readily understood by reference to the pearl-oyster, (_Avicula
margaritifera_,) which is so largely imported for the manufacture
of mother-of-pearl ornaments. A remarkable species is found in the
Lias, called, from the great disproportion in the size of the shells,
_Avicula inæquivalvis_, (_Lyell_, p. 274.) The recent species are
inhabitants of warm climates.
Our limits will not admit of further notice of the _Monomyaria_, and we
proceed to the second division of the plated-gilled mollusca.
Dimyaria: _Bivalve Shells, with two muscular imprints_.
The conchifera, or bivalve shells, of this group, found fossil, are
more than double in number those of the preceding; nearly eight
hundred species are known in the rocks of Great Britain, of which by
far the greater number is marine. But we must restrict our notice of
this division to a few genera, that more space may be devoted to that
important class, the Cephalopodous Mollusca.
The _Cardium_, _Venus_, and Mussel shells, are familiar examples of the
_Dimyaria_. The conglomerates, now forming in the British Channel, from
accumulations of the recent species of Cockle (_C. edule_), have been
previously noticed; see _Lign. 124_, p. 386. In the strata of England
there are upwards of thirty species: the Crag contains several,
particularly a large and delicate shell, the _Cardium Parkinsoni_
(_Min. Conch._ tab. 49). Others are peculiar to the London clay, as the
_Cardium semigranulatum_, a beautiful shell, having the surface smooth,
except on the posterior side, which is covered with strong ridges,
beset with minute granules; it is found in many localities (_Min.
Conch._ tab. 144). Among the silicified shells of the Shanklin sand of
Devonshire, an elegant Cardium, _C. Hillanum_, (_Min. Conch._ tab. 14,)
occurs. But one species is known in the formations below the Lias: the
_Cardium striatum_, (_Murch. Sil. Syst._ tab. 6, _fig._ 2,) found in
the Aymestry limestone.
[Sidenote: VENERICARDIA. PECTUNCULUS.]
Venericardia. _Ly._ p. 199.--These shells are abundant in the tertiary
strata; one large species, _V. planicosta_, (_Ly._ p. 199, _fig._ 171,)
is found in immense quantities in the clay and sand at Bracklesham Bay,
in Sussex, from the young to the adult state; some examples are very
large, and perfect. In the sand at Grignon, near Paris, the same shell
is abundant, possessing the usual white and delicate aspect of the
fossils of that celebrated locality of the _Calcaire grossier_. Only
one species has been noticed in the British secondary strata.
Pectunculus. _Wond._ p. 244, _fig._ 8.--In the London clay at
Bracklesham Bay, Highgate, Hordwell Cliff, and in the arenaceous
limestone of Bognor rocks, an immense number of the bivalve shells,
called _Pectunculi_ (_little pectens_), occur. Some of the French
marine tertiary strata also abound in the same, and other species of
this genus. In the above-mentioned Sussex localities, these shells are
so numerous, as to be the most frequent fossils that come under the
notice of the collector. They are readily known from their associates
by their rounded equivalve shells, and the single arched row of teeth
along the hinge, resembling the common _Arca_.[366] (See _Min. Conch._
tab. 27). At Plumstead, near Woolwich, a smaller species is found; and
also occasionally with the oysters at Bromley.
[366] The species so abundant at Bognor, is _P. brevirostris_, _Min.
Conch._ tab. 472. I have seen a block of the limestone, in which,
spread over an area of a foot square, there were upwards of fifty
specimens lying in relief.
Nucula.--Several species of a small elegant bivalve, related to the
preceding, but distinguished by having two rows of teeth on the hinge,
diverging from an interspace between the beaks, are found in the
Crag and other tertiary deposits (_Min. Conch._ tab. 180, 192). Two
species occur in the Galt (_Foss. South D._ pl. xix. _fig._ 5, 6, 9),
at Ringmer, Folkstone, Bletchingley, &c., sometimes with the shell
perfect, but generally in the state of casts composed of indurated
clay, and having impressions of the muscles and of the two rows of
hinge-teeth. The shell of one species is marked with fine transverse
grooves, or striæ (_N. pectinata_); the other is of a flattened ovate
form, and the surface smooth (_N. ovata_).
The most beautiful species of Nucula are the _N. bivirgata_ of the Galt
of Folkstone, and _F. Cobboldiæ_ of the Norwich Crag.
The species of _Nucula_ with the posterior side produced into a long
beak have been separated under the name _Leda_; they have a pallial
sinus, indicating a siphon to the mantle;--
_e.g._ _Nucula ovum_ Alum Shale.
_ -- claviformis_ Lias.
_ -- attenuata_ Coal Shale.
_ -- arctica_ Norwich Crag.
[Sidenote: PINNA. MYTILUS. MODIOLA.]
Pinna.--The common large _Pinna_, of the Mediterranean, is well
known, and differs so entirely from other shells, as to be readily
distinguished. There are about fifteen or sixteen British fossil
species. The earliest appearance of this genus is in the Carboniferous
Limestone of Derbyshire (Phil. York. tab. 6), in which there are
two species. The Lias contains one species; the Oolite eight; the
Cretaceous formation four; and the London clay two. One of the
tertiary species, _Pinna affinis_ (_Min. Conch._ tab. 313), occurs in
considerable numbers in the Bognor rocks, associated with Pectunculi;
it varies in length from one to six or seven inches. A beautiful and
delicate species is found in the _Calcaire grossier_ of Grignon. Shells
of this genus are very rare in the White Chalk, most of the supposed
_Pinnæ_ being imperfect examples of _Inocerami_; but I have seen
specimens from Norfolk (collected by the late Mr. Woodward), and one
from Sussex, in the cabinet of the Marquess of Northampton.[367]
[367] Dr. Lee has recently discovered in the Kimmeridge Clay on his
estate at Hartwell, Bucks, a species of Pinna not previously observed
in England. Professor Forbes informs me that it resembles _Pinna
conica_ (of Röemer), and is related to _P. lanceolata_ of Sowerby, but
appears to be distinct from both.
Mytilus, or Mussel.--There have been found about twenty species of
this well-known genus of marine shells in the British strata. They are
sparingly distributed through the several formations, from the Silurian
to the newer Tertiary. One species (_Mytilus Lyellii_, _Wond._ p. 405,
fig. 2) occurs in the Wealden, associated with fresh-water shells.
Of the genus termed Modiola, which comprises those mussels that have a
rounded anterior termination, nearly forty British species have been
discovered; ranging through the fossiliferous strata, from the Silurian
to the Crag. A beautiful species (_Modiola elegans._ _Min. Conch._ tab.
9), with the shell generally retaining its pearly coat, is found in the
London Clay, and in the limestone of Bognor.
An undescribed striated _Modiola_ (which may be named _M. striata_,
since the striæ are peculiar), occurs in the Kimmeridge Clay, at
Hartwell.
Those species of Modiola, which excavate hollows in stones, and inhabit
them, are arranged in a genus termed _Lithodomus_. The occurrence of
these shells in the remaining erect pillars of the Temple of Jupiter
Serapis (_Wond._ p. 106), at Puzzuoli, has afforded important and
unequivocal evidence of the physical mutations which that part of
Italy has undergone. Two species of Lithodomi have been found, by Mr,
Lonsdale, in the Oolite.
Pholadomya. _Ly._ p. 272, _fig._ 290.--This genus of shells
(established by Mr. James De C. Sowerby in the Min. Conch. 1826),
comprises about twenty British fossils, all of which, with but two
exceptions, occur in the Lias and Oolite. They are equivalved shells,
with the posterior end short, and rounded, and the anterior elongated
and gaping. The surface is generally marked with ribs, or alternate
elevations and depressions, diverging obliquely from the beaks to the
margin. In the clay at Osmington and Radipole, near Weymouth, a large
species (_P. æqualis_, _Min. Conch._ tab. 546) is abundant. The Oolite
of Brora, in Scotland, contains several species. The only species found
in our Chalk, is the beautiful shell (_P. decussatum_), figured _Foss.
South D._ tab. XXV. _fig._ 3, and first discovered by me, in 1820, in
a bed of Chalk Marl, which at that time was exposed at low-water, at
the base of the cliff at Brighton, near the present entrance to the
Chain-pier. The same species has since been found at Clayton, Hamsey,
Southbourne, and other localities of the Marl.
[Sidenote: FOSSIL PHOLADES.]
Pholas. _Lign. 166, fig. 5, 6._--The common boring bivalve called
Pholas, must have attracted the attention of every stroller by the
sea-shore, from the numerous perforations in blocks of chalk, and
other limestones, occasioned by its operations. Some species burrow
in wood, and often commit serious ravages in piles and other submarine
works constructed of timber. In the earlier ages of our planet we
find evidence of the existence of the same kind of living instruments
for the disintegration of floating wood, and the reduction of masses
of rock into detritus. But no traces of these shells have been
found in strata below the Oolite. One species occurs in the Coral
Rag, another in the Kimmeridge Clay; two in the Galt and Greensand;
and three or four in the tertiary deposits. In the Crag, blocks of
stone are occasionally found with the shells of _Pholades_ occupying
the perforations they originally formed and inhabited. But all the
specimens I have observed in the Galt, Greensand, and Oolite were
_xylophagous_ (_wood-eating_) species. In the Shanklin Sand, masses of
fossil wood, literally honey-combed by the perforations of Pholades,
are frequent; but the shells themselves are rare. Mr. Sowerby has
figured a beautiful specimen of silicified wood, from Sandgate, with
numerous shells of this genus (_Pholas priscus._ _Min. Conch._ tab.
581). _Lign. 166, fig. 5_, represents a fragment of fossil wood, with
three shells _in situ_; _a_, a shell seen longitudinally; and below,
the rounded anterior extremities of two other shells are exposed.
Masses of wood perforated by Pholades, from which all traces of the
shells have disappeared, have given rise to some curious fossil
remains, which are often very enigmatical to the young collector.
In the Kentish Rag, as for example, in Mr. Bensted's quarry, near
Maidstone, large blocks of stone are found, covered with groups of
subcylindrical mammillary projections, which are obtuse or rounded
at the apex. In some examples the interstices between these bodies
are free; in others they are occupied by a reddish brown, friable
substance, presenting obscure indications of ligneous structure:
and rarely, distinct woody fibres may be observed, the direction of
which is transverse, or nearly at right angles, to the mammillated
projections. These blocks are, in truth, the stony casts of cavities
formed by Pholades, in masses of wood, both the vegetable structure,
and the shells, having perished.
In the White Chalk specimens of this kind are occasionally found.
A remarkable fact, relating to some of the specimens from the Iguanodon
quarry, remains to be mentioned. Upon breaking off the projections,
to ascertain if any traces of the shells of the Pholades remained,
we discovered in several, near the apex, a univalve shell, a species
of _Nerita_. _Lign. 166, fig. 6_, represents a fragment of stone
with two of the casts, which have been broken, and in each, at _a_, a
univalve is imbedded. At _b_, the ligneous structure of the original
wood is visible. The only hypothesis that will account for the
appearance of these univalves in their present position, is that of
supposing that the Nerites crawled into the cavities made in the mass
of timber, after the shells of the Pholades had been removed; and that
the wood became imbedded in a sand-bank, and the univalves enclosed in
the cavities; the ligneous structure in a great measure perished, and
the stony casts of the perforations of the borers, with the imprisoned
univalves, remained. The Nerites, as shown in the example figured,
do not occupy any particular position in the tubes; one has the apex
towards the end of the cavity, and the other lies in a transverse
direction.[368]
[368] In a fragment of a perforated column, from Puzzuoli, in my
possession, by favour of Sir Woodbine Parish, there were numerous
living univalves in the cavities made and previously inhabited by the
lithodomi.
[Sidenote: TEREDO.]
Teredo. _Ly._ p. 24.--It will be convenient to notice in this place
another genus of boring shells, whose fossil remains are far more
abundant than those of the Pholas. The _Teredo navalis_, or Ship-worm,
which is the most vermiform of all the mollusca, forms tortuous
cylindrical hollows in wood; and in some climates commits the most
extensive injuries to ships, the piles of harbours, bridges, and other
submarine works formed of timber. A reference to the illustration given
by Sir C. Lyell will render detailed description unnecessary. The
_Teredo_ is furnished at one extremity with testaceous valves, by which
it bores its way into the wood, while from the surface of its soft body
a calcareous matter is secreted, which lines with a shelly covering
the hollows or channels formed by the animal in its progress. The
fossil species differ from the recent in the valves being united to the
calcareous tube. Wood perforated by _Teredines_, and occupied by their
shelly tubes, occurs in almost every locality of the London Clay. Those
specimens in which the wood is petrified, and the cavities of the tubes
are filled with calcareous spar of various colours, furnish beautiful
sections, when cut and polished (_Pict. Atlas_, pl. viii. _fig._ 8,
9). When the canal in the Regent's Park was being formed, large blocks
of perforated calcareous wood were discovered, having the ligneous
structure well preserved, and the tubes of the Teredines occupied by
yellow, grey, and brown spar, forming specimens of great beauty and
interest. Wood, with Teredines, or some analogous boring mollusks,
occurs sparingly in the chalk of this country; but in the cretaceous
strata at Maestricht, large masses are frequently found.[369] Fossil
wood may occasionally be observed with perforations that have been made
by other kinds of boring shells; but the preceding remarks will suffice
to convey an idea of the nature and origin of such appearances.[370]
[369] In the British Museum there is a mass of silicified wood from the
Upper Greensand of Blackdown, perforated by a Teredo, whose valves
remain in the burrows.
[370] Other genera of boring shells also occur fossil, as Fistulana,
Gastrochæna (_Min. Conch._ tab. 526), Saxicava (_Min. Conch._ tab.
466).
Trigonia. _Lign. 127, fig. 1, 2, 4._--These bivalves are related to
the _Arcadeæ_ and _Nuculæ_, but distinguished by the peculiar character
of the hinge; the right valve has two large oblong teeth, which
diverge from the umbo, and are strongly furrowed, and fit into two
corresponding grooved cavities, in the opposite, or left valve. These
shells are very thick and nacreous; they abound in certain strata of
the Oolite and lower Cretaceous formation, but have not been observed
in any deposits of this country older than the Lias; there are nearly
thirty British species. Two living species of Trigonia (_Trigonia
margaritacea_ and _T. Jukesii_) are known, both inhabitants of the
seas of New Holland, where they are associated with Terebratulæ. Some
of the argillaceous beds of the Oolite, as the Oxford and Kimmeridge
clays, abound in Trigoniæ; Osmington and Radipole, near Weymouth, are
celebrated localities for these fossil shells, which are found there
in great perfection; and on the French coast, where similar strata
appear, the Trigoniæ are equally abundant. Under the cliffs, near
Boulogne harbour, the shore is strewn with them. Three common species
are figured in _Lign. 127_. The casts of most of the species are
smooth, as in _fig. 2_; and the collector should, therefore, search
for impressions of the outer surface, when the shell is absent, as is
generally the case in the Portland Oolite and Shanklin Sand, in which
Trigoniæ are very numerous. Near Highworth, in Wiltshire, very fine and
large examples of _Trigonia costata_, _fig. 4_, occur, with the shell
preserved. The impressions of the large, oblong, diverging teeth of the
hinge, are usually so strongly marked in the casts, as to render it
easy to identify the shells of this genus. The quarries of the Portland
Oolite at Swindon, Wilts, teem with casts of Trigoniæ, collocated with
Ammonites. In the Isle of Portland they are also very numerous, some
beds of stone being so friable, from the numerous cavities left by the
removal of the substance of the shells, as to be unfit for paving,
or other economical purposes. Very sharp casts may be obtained from
this rock by merely breaking the stone to pieces. In the Whetstone
of Blackdown, Devon, beautiful silicified Trigoniæ are occasionally
found. Tisbury, in Wiltshire, yields very fine specimens, and in some
examples, Mr. G. B. Sowerby has detected remains of the ligament.
FOSSIL FRESH-WATER BIVALVES.
[Sidenote: FOSSIL FRESH-WATER BIVALVES.]
The animals of the shells hitherto described are, with scarcely any
exception, inhabitants of the sea; and the marine origin of the strata
in which they occur, may consequently be inferred, with but little
probability of error. I now propose noticing the fossil remains of
those bivalves which inhabit rivers, lakes, streams, and pools of
fresh water. The marine, or fresh-water, character of fossil shells,
is inferred from their resemblance to the recent mollusca, whose
habits are known; for the shells alone present no unequivocal marks,
by which even the experienced conchologist can pronounce whether an
extinct form belonged to a marine or to a fluviatile mollusk, although
certain characters may admit of an approximative inference. Thus, for
instance, as none of the known living fresh-water bivalves belong to
the previous division, the _Monomyaria_, the presence in a stratum of
numerous shells with but one muscular impression, would afford a fair
presumption of the marine origin of such, deposit. The remains with
which the shells are associated and the mineralogical characters of
the strata in which they occur, would, of course, afford important
corroborative evidence.[371]
[371] See Sir C. Lyell on the distinction between fresh-water and marine
deposits. _Ly._ p. 27, _et seq._
The living fresh-water bivalves comprise but a few genera and species;
and those which have been found fossil in the British strata belong to
but four or five genera. Their distribution is restricted to strata
of undoubted fluviatile origin, and to those local intercalations of
fresh-water and land productions in marine deposits, which occur in
some of the secondary, and in many of the tertiary formations.
Unio. _Ly._ p. 28.--The river Mussels, or _Unionidæ_, have a solid,
pearly shell, with two principal and two lateral teeth on the hinge;
and their umbones, or bosses, are generally smooth, or longitudinally
undulated. Those which have no cardinal teeth are arranged under the
genus _Anodon_: but it is not necessary for our present purpose, to
enter into minute conchological distinctions. In number, variety, and
beauty, the species which inhabit the large rivers of North America
present a striking contrast with the few and homely British fresh-water
mussels; nor have we, in a fossil state, any shells of this family
at all comparable with those living types.[372] The earliest fossil
Mollusca referred to the genus _Unio_ appear in certain layers of
clay and argillaceous ironstone belonging to the Carboniferous system
of Derbyshire, Coalbrook Dale, &c. (_Min. Conch._ vol. i. tab. 33).
In the former county, these strata are termed _mussel-band_;[373] and
some beds constitute a compact shell-limestone, which admits of being
manufactured into vases, &c., and takes a good polish; the sections
of the shells in this marble are white, on a dark ground. There is,
however, considerable doubt whether any of the Carboniferous shells
really belong to the genus _Unio_; some geologists refer them to
_Cardinia_, a group of sea-shells found especially in the Lias.
[372] See American Journal of Science, vol. xlvii. p. 402, "Unionidæ."
[373] "A solid stratum of ironstone, which extends from Tupton Moor to
Staveley." Martin's Petrificata Derbiensia, pl. xxvii.
The earliest undoubted shells of this genus from the British strata,
are, I believe, those first discovered by me in the strata of Tilgate
Forest, (_Foss. South D._ p. 45, and _Foss. Tilg. For._ p. 57), and
subsequently found in numerous localities of the Wealden.[374]
[374] They are figured in Geol. S. E. p. 250; and in Dr. Fitton's
Memoir, Geol. Trans, vol. iv. pl. 21.
* * * * *
[Illustration: Lign. 131. Unio Valdensis. (1/3 _nat._)
_Wealden; Isle of Wight._]
In 1844 I discovered a large species in the Wealden at Brook Point.
I have named it _Unio Valdensis_.[375] I have collected and obtained
nearly fifty specimens; they present two varieties, the one contracted
and narrow, the other broader and deeper; this difference is probably
sexual; the wide and deep shells may be the females; for in the living
American Uniones the same characters are observed. Some examples are
remarkably well preserved; the ligament remaining in a carbonized
state, and the body of the mollusk in the condition of molluskite; even
a tint of the original tawny reddish colour of the shell is present.
The same species has been found in the Wealden strata, near Tunbridge
Wells, by Mr. Barlow, C. E.
[375] _Unio Valdensis_ resembles in form the Mexican species, U.
Panacöensis (River Panaco), but is probably more nearly allied to
an unnamed Australian species of which Mr. G, Sowerby has numerous
examples.
I shall reserve my remarks upon the important aid these fossils
afforded in the determination of the fluviatile origin of the Wealden,
for our _Excursion to Tilgate Forest_.
[Illustration: Lign. 132. Cyclas and Melanopsis. _Wealden; Sussex._]
Cyclas. _Wond._ p. 404. _Ly._ p. 28.--Another genus of fresh-water
bivalves is termed _Cyclas_, of which there are ten species in the
Wealden formation: and, with the exception of four or five recent
forms, which occur in the tertiary fresh-water strata, none others
have been found in England.[376] The shells of the genus Cyclas are
oval, transverse, equivalved bivalves, with the hinge-teeth very
small: the substance of the shell is thin and fragile; the figures in
_Wond._ and _Ly._ accurately represent the appearance of the fossil
_Cyclades_ of the Wealden, and tertiary strata. Entire layers of two
or three species of these shells occur in the argillaceous deposits of
the Wealden, generally in a friable state, but from among the masses
of crushed shells, perfect specimens may be obtained, and sometimes
with the remains of the epidermis and ligament. The hard stone, termed
calciferous grit, in the neighbourhood of Hastings, Tilgate Forest,
Horsham, and other places in the Weald of Sussex, abounds in casts of
the same species, associated with the _Uniones_, previously described.
In the cliffs on the southern shores of the Isle of Wight where the
Wealden beds emerge, and also in the Isle of Purbeck, these shells are
equally abundant. Together with the _Uniones_, they occasionally appear
in the limestone, called Sussex Marble; and in the Isle of Purbeck
there are beds of limestone wholly composed of bivalves belonging to
these two genera, and presenting, in polished slabs, markings formed by
sections of the enclosed shells.
[376] _Cyrena_, is a genus so nearly related to Cyclas, that it is
difficult to distinguish them, and it will be convenient to retain only
the former name.
FOSSIL PTEROPODA.
[Sidenote: PTEROPODA. GASTEROPODA.]
In the Ludlow strata there are found small fragile elongated conical
shells without chambers, which are supposed by Professor E. Forbes to
be identical with a recent genus of pteropodous mollusca, common in the
Mediterranean, called Creseis. They seldom exceed two inches in length.
Of another genus, named Conularia, six Species have been discovered in
the Silurian formation.[377]
[377] See Geol. Trans, second series, vol. vi, p. 325.
[Illustration: Lign. 133. Fossil Shells of Gasteropoda.
Fig. 1.--Paludina fluviorum. _Wealden._
2.--Limnæa longiscata. _Tertiary. Isle of Wight._
3.--Cerithium lapidorum. _Tertiary, Grignon._
4.--Fusus contrarius. Crag. Essex.
]
FOSSIL SHELLS OF GASTEROPODA.
The univalve shells, as we have previously explained, are the
calcareous cases, or coverings, of a more highly organized class of
molluscous animals, than the inhabitants of the bivalves (see p.
366), for they possess a head and mouth with jaws, eyes, and feelers;
and while the _Acephala_, with but few exceptions, are incapable of
locomotion, the _Encephala_ are almost all of them furnished with
organs of progression, and can creep, climb, and swim, or float on the
surface of the water. Their shells are for the most part formed of
one valve, hence the name of _univalve_; but in some species it is
composed of several pieces. The most simple form of shell is that of
the hollow cone, of which the _Patella_, or limpet, affords an example;
and in the more complicated modifications, the cone is twisted, or
convoluted spirally, either in the same plane as in the _Planorbis_
of our rivers, or obliquely, as in by far the greater number of
species. The direction of the spire is generally from left to right,
the aperture being dextral to the observer when the shell is placed
with its apex uppermost, as in _Lign. 133, figs. 1, 2, 3_; but in a
few species the spire turns in the opposite manner, and the mouth or
aperture is to the left, or sinistral, as in _Lign. 133, fig. 4_.
In consequence of the form of the aperture of the shell, the entire
or notched condition of its margin, and the presence or absence of a
canal or siphon always having relation to the soft parts of the animal,
these characters afford data by which the genera and species of the
shells may be determined, and information obtained as to the structure
and economy of the originals.
The Gasteropoda generally creep by means of a fleshy disk, or foot,
which is situated under the belly. Some kinds are terrestrial, others
inhabit trees, many live in rivers and streams, others in stagnant and
brackish waters; but the greater number are denizens of the sea.
[Sidenote: FOSSIL GASTEROPODA.]
The Common Snail, River Snail, and Periwinkle, are instances of
terrestrial, fluviatile, and marine forms. The organs of respiration
are situated in the last whorl of the shell; and in some genera
the border of the mantle, or integument surrounding the body, is
prolonged into a siphon, by which the water is freely admitted,
without the head or foot being protruded: in these mollusks the shell
has a corresponding channel to receive the siphon, as in the Whelk,
or Buccinum, and in the fossil shell _Lign. 133, fig. 4_. The
Gasteropoda are generally provided with an operculum, or movable valve,
by which the aperture is closed and defended when the animal retreats
within its shell. In some species the operculum is a mere horny
pellicle; in others it is a solid calcareous plate of considerable
relative thickness. These mollusca, as is but too well known of the
terrestrial species, consume large quantities of food. Some are
herbivorous, and others carnivorous; many prey on living, and others
on decaying animal and vegetable substances.[378] As in a fossil state
the shells alone remain to afford any clue as to the structure and
economy of the originals, characters have been sought for, by which
the fluviatile or marine nature, and the carnivorous or herbivorous
habits of the living mollusca may be determined. As a general rule,
it will be found, that the shells of terrestrial and fresh-water
Gasteropoda have the aperture entire, as in the Garden Snail, and in
the fossil shell, _Lign. 133, fig. 1_; and that a large proportion
of the marine species have the opening notched or channelled, as in
the Whelk, and _Lign. 133, figs. 3, 4_; and most of the species with
entire apertures are herbivorous. But these inferences must be regarded
in a very general sense, and it will require corroborative evidence to
establish the marine or fresh-water nature of those fossil shells which
do not bear a close analogy to known living species.[379]
[378] "All _Gasteropoda_ commence life under the same form, both of
shell and animal, namely, a very simple helicoid shell, and an animal
furnished with two ciliated wings or lobes, by which it can swim freely
through the fluid in which it is contained. At this stage of existence
the animal corresponds to the permanent state of the _Pteropod_, and
the form is alike, whether it be afterwards a shelled or a shell-less
species."--Prof. E. Forbes, Edin. Philos. Journal, vol. xxxvi. p. 326.
The well known Tiger Cowry (_Cyprcea tigris_) in its earliest stage has
a minute helicoid (snail-like) shell.
[379] See _Ly._ p. 30.
The various conditions in which the remains of univalve shells occur in
the mineral kingdom have already been so fully explained, that but a
few additional remarks on that subject are required (see p. 382).
The Gasteropoda are found to progressively diminish in number with
the antiquity of the deposits, and it was once supposed that this
type of molluscous organization was not contemporaneous with the
ancient Cephalopoda. My discovery of several genera associated with
Ammonites in the chalk (see _Foss. South D._ pl. xviii, xix) first
tended to invalidate this hypothesis; and the subsequent researches
of Dr. Fitton, Professor Phillips, and other geologists have shown
that the presence or absence of Gasteropoda in a stratum may generally
be ascribed to the circumstance of the deposit having been formed
in shallow, or in deep water. Thus when simple univalves largely
predominate under circumstances that indicate they were imbedded in
their native habitats, it may be safely concluded that the rock is of
littoral formation; or, in other words, was deposited in shallow water,
near the sea-shore; and, on the contrary, when Nautili, Ammonites,
and the shells of other mollusca known to live in deep waters abound
in a formation, it may be presumed that the strata were formed in the
tranquil depths of the ocean. The number of described species from
the British strata is nearly eight hundred; and these are distributed
throughout the sedimentary formations, from the Silurian to the newest
Tertiary; the latter containing by far the greater proportion.
[Sidenote: FOSSIL FRESH-WATER UNIVALVES.]
Fresh-water Univalves.--The fossil shells of Gasteropoda that are
undoubtedly fluviatile, comprise but few genera and species, and are
confined to those deposits, which, from the corroborative proofs
afforded by other organic remains, are unquestionably of fresh-water
origin. Such are the intercalated beds of clay and limestone in the
London and Paris basins, the Wealden formation, and certain strata in
the Carboniferous system. The most numerous specimens are principally
referable to the common fluviatile genera, _Paludina_, _Limnæa_,
_Planorbis_, and _Melanopsis_ (see _Ly._ p. 29).
Paludina. _Lign. 133, fig. 1._ (_Wond._ p. 401, _Ly._ p. 29.)--This
common river shell is of a conoidal form, and the whorls of the spire,
and the aperture, are rounded. Eleven British species are known. In
the tertiary fresh-water beds of Headon Hill, at Alum Bay, Paludinæ
with the shells perfect, and of a dull white colour, are abundant;
and also in the limestone at Shalcombe, in the Isle of Wight, in the
state of casts. In both these localities the Paludinæ are associated
with other fresh-water shells. But the grand deposit of shells of
this genus is the Wealden formation; throughout which there are
extensive beds of marble, coarse limestone, and clays, almost wholly
composed of Paludinæ, and minute fresh-water Crustaceans, of the
genus _Cypris_, which will be described in a subsequent chapter. The
compact paludina-limestone of Sussex, called Petworth or Sussex marble,
is principally made up of one species, the _P. fluviorum_, _Lign.
133, fig. 1_, and is an aggregation of Paludinæ, held together by
crystallized carbonate of lime; the cavities of the shells, and their
interstices, being often filled with white calcareous spar. A polished
slab, displaying sections of the enclosed shells, is figured in _Wond._
p. 402. Upon examining slices of this marble with the microscope, the
cavities of the shells are found to contain myriads of the cases of
Cyprides.[380] The Wealden limestone of the Isle of Purbeck, _Lign.
134_, known as Purbeck marble, is, in like manner, composed of Paludinæ,
but of a much smaller species. Both these marbles were in great
repute with the architects of the middle ages, and there are but few
of our cathedrals and ancient churches which do not still contain
examples, either in their columns, monuments, or pavements, of one or
both varieties. The polished marble columns of Chichester Cathedral,
and those of the Temple Church, in London, are of Purbeck marble; in
other words, they are composed of the petrified shells of snails, that
lived and died in a river, flowing through a country inhabited by the
Iguanodon and other colossal reptiles, all of which have long since
become extinct. With the exception of the _mussel-band_ limestone of
the Carboniferous system, previously described, these are the only
British fresh-water marbles[381] There are four species of Paludina in
the Wealden, and four in the Tertiary strata of Hants.
[380] For a particular account of this marble, see Geol. S. E. pp.
182-187.
[381] The collector may obtain specimens, and polished slabs of these
limestones, of Mr. Martin, mason, Lewes, Sussex.
[Illustration: Lign. 134.
Polished Slab of Purbeck Marble.]
Limnæa. _Lign. 133, fig. 2._--Several species of these fresh-water
mollusks inhabit our lakes and ponds, and may be known by their pointed
spire, elongated oval body, and delicate thin shell: on the inner lip
of the aperture there is an oblique fold. Fossil shells of this genus
are found with Paludinæ in the fresh-water tertiary deposits. Headon
Hill and other localities in the Isle of Wight abound in these shells;
and in the limestone of Calbourn beautiful casts are very numerous.
The Paris basin yields several species; and there are six species in
the Isle of Wight Tertiary; I have not observed any decided examples
in the Wealden. In the sands and clays the shells are well preserved;
in the limestones the casts only remain. Shells of another genus of
fresh-water spiral univalves, termed _Bulimus_ (_Ly._ p. 30), are found
associated with the above. A large species (_B. ellipticus_, _Min.
Conch._ tab. 337), occurs in the limestone at Binstead, near Ryde,
and at Calbourn; I have collected specimens two inches long from the
former locality; they are generally in the state of casts, with a white
friable coating of the shell.[382]
[382] A very large species of _Limnæa_ from Bavaria (labelled _L.
maxima_) is in the British Museum. It is a cast six and a half inches
long, and is placed with the recent shells. Prof. E. Forbes has
discovered a Limneïd (_Physa_) in the Purbeck strata.
Planorbis. _Ly._ p. 29. _Wond._ p. 400.--The shells of this genus
are also numerous in our rivers and lakes, and may be distinguished
by their discoidal form, the shell being coiled up in a nearly
vertical plane. There are about twenty living species; and sixteen are
enumerated as fossil in the British tertiary; five occur in the Isle
of Wight basin, in the localities of the fresh-water genera already
mentioned; Headon Hill, in particular, yields shells of this genus in
great abundance and perfection.
Melanopsis. _Ly._ p. 29.--These are spiral univalves, the appearance
of which will be better understood by the figures, than by any
description. I allude to this genus because a small species is very
numerous, with the other fresh-water shells, at Headon Hill; and two or
more species are found in the argillaceous strata of the Wealden (see
_Geol. S. E._ p. 249, and _Lign. 132_).
[Sidenote: FOSSIL MARINE UNIVALVES.]
Marine Univalves.--Of the fossil marine Gasteropoda there are no less
than eighty genera in the strata of the British Islands, and the
species amount to several hundreds. To distinguish the species and
genera, reference must, of course, be made to works expressly devoted
to fossil conchology, as Sowerby's _Mineral Conchology_, and _Genera
of Fossil Shells_; or to the works of French authors, particularly
those of Lamarck, edited by M. Deshayes, and of M. Blainville. The
_Penny Cyclopedia_ contains admirable notices of fossil shells, under
the respective heads of the classes, orders, and genera, of the recent
Mollusca.
Buccinum, of which the common Whelk is an example.--Fusus, _Lign.
133, fig. 4_. _Wond._ p. 244.--Pleurotoma, _Ly._ p. 31. _Wond._ p.
244.--Cerithium, _Lign. 133, fig. 3_. _Wond._ p. 244.--Ancilla,
_Wond._ p. 244. _Ly._ p. 31.--Voluta, _Ly._ p. 202, _fig._ 180.--Murex,
_Ly._ p. 164.--Rostellaria, _Ly._ p. 201.--To the eight genera here
enumerated a very large number of the marine simple univalve shells
belong; and they are principally found in Tertiary strata.
The animals of these shells are characterized by their respiratory
organs, which are formed of one or two pectiniform gills, with a tube
or siphon more or less elongated, for the free admission of sea-water
to the branchial apparatus. This organization is indicated in the
shell, either by a notch, or by a prolonged tubular canal. All the
species are, with scarcely any exceptions, inhabitants of the sea, and
carnivorous.
I have selected for illustration of the genus _Fusus_, a celebrated
shell of the Crag, known among collectors as the "_Esssex reversed
Whelk_," _Lign. 133, fig. 4_; the spire is twisted in the opposite
direction to the usual mode, and the mouth is consequently to the left
of the observer; the same species occurs with the spire in the common
direction. The shells of the genus _Pleurotoma_ are distinguished by an
incision, or notch, in the side of the right or outer lip; and those
of _Cerithium_, by the form of the mouth, see _Lign. 133, fig. 3_.
The latter is a very numerous genus, and more than two hundred
fossil species are enumerated; it contains many elegant forms. The
Tertiary strata at Grignon are particularly rich in these fossils;
the shells are of a pearly whiteness, and as perfect as when recent.
Some Cerithia are of considerable size; the _C. giganteum_ is from ten
to fourteen inches in length. The genus Potamides comprehends shells
closely resembling the Cerithia in form, but which are inhabitants of
fresh-water.[383] This is an instance of the difficulty which sometimes
exists of arriving at certain conclusions as to the habits of the
mollusks, from their testaceous coverings alone.
[383] Mr. Woodward informs me that they can only be distinguished when
_fossil_, by the absence of _varices_, or "periodic mouths." The recent
species are known to be inhabitants of fresh-water, by their dark
epidermis, corroded points, and horny multi-spiral _opercula_.
The Plastic Clay beds at Castle Hill, Newhaven, and in the vicinity
of Woolwich, abound in two species of shells, which were originally
described by Mr. Sowerby, as _Cerithia_ (viz. _C. funatum_ and _C.
melanoides_),[384] but are now referred to the fresh-water genus,
Melania; by some conchologists to _Potamides_. At Castle Hill they
are accompanied by fresh-water bivalves, and leaves of dicotyledonous
plants.
[384] Foss. South Downs, tab. xvii. figs. 3, 4.
Of the genus _Rostellaria_, there is a remarkable species in the London
Clay, called _R. macroptera_, from the large wing-like expansion of its
outer lip, in adult specimens; see _Ly._ p. 201. An elegant Rostellaria
is found in the Galt, at Folkstone,[385] (_Foss. South D._ tab. xix.
figs. 12, 14,) and other localities; and also in the Chalk Marl.
[385] "This shell belongs to the recent genus, _Aporrhaïs_, and is
related to Cerithium, not to Strombus."--_Mr. Woodward._
* * * * *
Casts of a large ventricose, globular univalve, called Dolium,[NV]
have been found in the Chalk Marl, at Clayton, near Hurstpierpoint, in
Sussex. This species is distinguished by its transverse tuberculated
bands; it is a very rare production of the lower chalk of Sussex
(_Min. Conch._ tab. 326). Turbinated shells related to _Trochus_, and
belonging to several genera, occur in the Cretaceous deposits. As is
the case generally with the univalves of this formation, but slight
traces of the shells remain; the thin internal nacreous lining is
sometimes found adhering to the cast.
[386] This Chalk fossil is not a _Dolium_: it is probably related to
_Ringinella incrassata_ (Geol. Suss. t. xix. _fig._ 3), one of the
_Tornatellidæ_, a family largely developed in the chalk.
In the Chalk of Touraine, species of the genera _Conus_ (_Lign. 135,
fig. 1_) and _Solarium_ (_Lign. 135, fig. 2_) are found with the
shells preserved. The specimens figured, _Lign. 135_, are selected to
familiarize the student with the difference so commonly observable,
between the outer surface of the casts, and that of the shells: in
both these fossils the shells are marked externally with lines and
tubercles; but the casts present only the smooth surface of the
interior of the shell in which they were moulded.
[Illustration: Lign. 135. Univalves, from the Chalk of Touraine.--_nat._
Fig. 1.--Conus tuberculatus, with part of the shell remaining
attached to the cast.
2.--Solarium ornatum, with the shell.
2_a_.--Specimen of the same species, deprived of the shell.
]
In the most ancient fossiliferous formations, the Carboniferous;
Devonian, and Silurian, many species and genera of Gasteropoda have
been discovered. Professor Phillips enumerates more than ninety in
the mountain limestone of Yorkshire (_Phil. York._), belonging to the
genera _Turbo_, _Pleurotomaria_, _Natica_, _Euomphalus_, _Loxonema_,
_Macrocheilus_, _Platyceras_, and _Metoptoma_. Thirty-four species from
the Silurian rocks are figured and described in _Murch. Sil. Syst._ p.
706.
The _Natica_, _Lign. 136, fig. 3_, sometimes attains thrice the size
represented, and has been found in many localities in England and
Ireland.
Pleurotomaria. _Lign. 136, fig. 4._--This is an extinct genus,
distinguished from Trochus by a fissure on the right lip, the position
of which is indicated by the band along the back of the whorl in
_Lign. 136_; several species occur in the Mountain Limestone; the
markings of the original shell are sometimes preserved, as in the
example delineated This genus is common in the Oolite; a splendid
species, with the shell entire, is found in the Kimmeridge Clay, at
Hartwell; limestone casts of the same species are abundant in the
Portland stone at Swindon, in Wiltshire.
[Illustration: Lign. 136. Univalves from the Mountain Limestone.
Fig. 1.--Euomphalus pentangulatus; Upper surface.
2.--Polished section of the same species.
3.--Natica plicistria. _Yorkshire. Mt. L._
4.--Pleurotomaria flammigera. (_Phil. York._) _Mt. L._
]
There are two species of this genus (formerly named _Cirrus_ by Mr.
Sowerby) which are of frequent occurrence in the White Chalk of
England, in the state of casts, and are figured in my _Foss. South D._
tab. xviii., under the names of _Cirrus perspectivus_, and _Trochus
linearis_. The Chalk Marl of Sussex yields in some localities (Hamsey,
Middleham, Clayton) fine casts of Pleurotomaria, which appear to be
distinct from those of the upper cretaceous strata.
[Sidenote: EUOMPHALUS.]
Euomphalus.[387] _Lign. 136, figs. 1, 2._--The shells of this extinct
genus are deeply umbilicated, discoidal, spiral univalves, having the
innermost whorls of the shell divided by imperforated partitions. The
internal structure of these shells will serve to prepare the student
for those more complicated forms of the testaceous apparatus presented
by the Cephalopoda, which will form the subject of the next chapter.
There are several recent univalves the animals of which retreat in the
progress of growth from the apex of the spire, and the vacated portion
is shut off by a shelly plate. In some genera a series of concave septa
are thus formed; but in others (as _Magilus_) the deserted cavity
is filled by a compact accretion of calcareous matter, and a solid
elongated shell is produced. The _Euomphalus_, of which there are many
species in the Silurian, Devonian, and Carboniferous strata, belongs
to the former group. As the animal increased in size, it deserted the
smaller and innermost portion of the spire, and a nacreous partition
was secreted by the posterior part of the mantle, the interspace
remaining hollow; as this process was repeated at different periods,
several cells were successively formed. This chambered structure is
shown in the specimen _Lign. 136, fig. 2_, in which the cells are
filled with spar, but the outer cavity is occupied by limestone like
that in which the shell was imbedded; a proof that no communication
existed between the chamber occupied by the body of the animal, and
the space from which it had withdrawn. The calcareous spar, as in
the vegetable remains previously described (p. 71), has percolated
the substance of the fossil, and crystallized in the innermost
cells. We shall again have occasion to refer to this interesting
fact, when investigating the chambered cells of the Cephalopoda. It
may be necessary to remark, that it does not appear that the vacant
interspaces in the Euomphalus served the special purpose of the
air-chambers of the Nautilus and Ammonite.
[387] So named by Mr. Sowerby, in allusion to the deeply umbilicated
character of the disk.
[Illustration: Lign. 137.
Murchisonia angulata.
_Devonian; Eifel_.]
Murchisonia. _Lign. 137._ An elongated spiral shell, having the outer
lip deeply notched, as in the Pleurotomaria (_a, Lign. 137_). There
are upwards of 50 species of this genus, which are characteristic of
the palæozoic rocks. They occur in the Permian, Devonian, and Lower
Silurian deposits; the specimen figured is from the Devonian, or Old
Red of the Eifel.
Chiton. Valves of Chitons have been found in the Magnesian limestone,
near Sunderland, by Prof. King, (_Permian Fossils_, _Pal. Soc._ p. 202,
pl. xvi.), and in the Silurian rocks of Ireland, by Mr. Salter, _Geol.
Journal_, vol. iii. p. 48.
[Sidenote: SPHÆRULITES.]
Sphærulites.[388] _Lign. 138._--No vestiges of a shell of this genus
had been noticed in the English strata, until my discovery of some
fragments in the Lewes Chalk in 1820; from the lamellated structure of
these fossils, I mistook them for corals, until specimens were obtained
sufficiently perfect to show the form of the originals; these were
described in the _Geol. S. E._ (p. 130), under the name of Hippurites.
But these fossils are more nearly related to the _Sphærulites_, which
differ from the shells of the former genus in having only one internal
longitudinal ridge, and in the external surface being roughened by
irregularly raised plates, as in _Lign. 138, fig. 1_, which is a
specimen from the Pyrenees, collected by M. Alex. Brongniart; the
operculum is seen at _a_.
[388] This genus has been referred by some conchologists to the
Bivalves, and by others to the Univalves.
[Illustration: Lign. 138. Sphærulites from the Chalk of France and
England.
Fig. 1.--Sphærulite, with its _operculum_, _a_.
2.--Sphærulites Mortoni (G. A. M.), _from Lewes_: 1/2 _nat._
2_a_.--Cellular structure of _fig._ 2, in a transverse section: ×
2_b_.--Structure, as seen in a vertical section: ×
]
The species found in the Sussex Chalk, _Lign. 138, fig. 2_, is
characterized by the longitudinal striæ on the outer surface. In some
examples there is an external longitudinal furrow, and a corresponding
internal ridge.[389]
[389] The specific name is in honour of Dr. George Morton, of
Philadelphia, author of the "Synopsis of the Cretaceous Group of the
United States."
The Sphærulites sometimes occur in groups in the Sussex chalk; I
had a large water-worn mass, consisting of five or six individuals,
anchylosed together. Some beautiful specimens collected by the late Mr.
Dixon from the Chalk, near Worthing, are now in the British Museum.[390]
The structure of the Sphærulite is accurately delineated in _Lign.
138, figs. 2a 2b_. The cavities of these shells are occasionally
filled with flint, but in general with chalk, which may be entirely
cleared away, as in _fig. 2_. The Hippurites of the limestone of the
Pyrenees are frequently occupied by calcareous spar, and the substance
of the shells is occasionally transmuted into the same mineral.
[390] Petrifactions, p. 468.
* * * * *
[Sidenote: MOLLUSKITE.]
Molluskite; or the carbonized remains of the soft parts of
mollusca.--Before proceeding to the consideration of that numerous and
important division of the mollusca the _Cephalopoda_, I will offer a
few remarks on a carbonaceous substance resulting from the gelatinous
matter of which the soft bodies of these animals are composed, and for
which I have proposed the name of _molluskite_, to indicate its nature
and origin.
[Illustration: Lign. 139. Coprolites and Molluskite. _Chalk and
Greensand._
Fig. 1.--Coprolite of a fish (_Macropoma_). _Chalk, Lewes._
2.--Coprolite of a fish (_Squalus_). _Chalk marl. Ramsey._
3.--Molluskite of a _Rostellaria_. (_Mr. Bensted._) _Kentish Rag,
Maidstone._
]
This substance is of a dark brown or black colour, and occurs either
in shapeless masses, which are irregularly distributed among the
shells and other organic remains, in sandstone, limestone, &c., or
as casts of shells, or occupying their cavities, as in the specimen
_Lign. 139, fig. 3_, which is a vertical section of a spiral univalve
(_Rostellaria_), filled with the soft parts of the animal, converted
into molluskite. Upon analysis this substance is found to contain
a large proportion of animal carbon.[391] The rocks of firestone at
Southbourne, on the Sussex coast, are mottled with brown molluskite
and hard amorphous concretions, consisting of carbon and phosphate of
lime, mixed with sand and other extraneous matter. Casts of shells,
of the genera Venus, _Arca_, &c., entirely composed of the same kind
of materials, are also abundant in those rocks. The lowermost bed of
Galt, at its line of junction with the Greensand beneath, at Folkstone,
and in many other localities, is largely composed of similar matter,
resembling in appearance the fossils called Coprolites, hereafter
described. The outer chamber of the Ammonites and other shells, so
abundant in the Galt, are often filled with this substance. But the
most interesting deposit of molluskite is in the Kentish Rag of Mr.
Bensted's quarry, near Maidstone. This phenomenon had not escaped
the notice of that intelligent and accurate observer, who liberally
placed at my disposal numerous shells, particularly of _Trigoniæ_ and
_Terebratulæ_, which were filled with molluskite, and large slabs of
the sandstone, full of concretionary and amorphous masses of the same.
The latter, Mr. Bensted suggested, may have been derived from the soft
bodies of the dead Mollusks, which, having become disengaged from their
shells and aggregated together, had floated in the sea, until they
became enveloped in the sand and mud, which have gradually consolidated
into the arenaceous stone termed Kentish Rag, In illustration of this
opinion, Mr. Bensted directed my attention to the following remarkable
fact, related in the _American Journal of Science_:--In the year 1836,
a fatal epidemic prevailed among the shell-fish of the Muskingum River,
in the state of Ohio. It commenced in April, and continued until June,
destroying millions of the mollusca that inhabited the beds of the
tributary streams, and the river. As the animals died, the valves
of the shells opened, and, decomposition commencing, the muscular
adhesions gave way, and the fleshy portions rose to the surface of
the water, leaving the shells in the bed of the river. As masses of
the dead bodies floated down the current, the headlands of islands,
piles of drifted wood, and the shores of the river, in many places,
were covered with them; and the air in the vicinity was tainted with
the putrid effluvium exhaling from these accumulations of decomposing
animal matter. The cause of the epidemic was unknown.
[391] Some of this _molluskite_ has, at my request, been analyzed by Mr.
Rigg, who obliged me with the following remarks:--"After removing the
lime by means of hydrochloric acid from ten grains of this substance,
there remained 1.2 grain of dark powder, which gave, by analysis with
oxide of copper, .16 of a cubic inch of carbonic acid, and a small
portion of nitrogen. On subjecting to the same kind of analysis two
grains of the darker body, without previously acting upon it by any
acid, .054 of a cubic inch of carbonic acid was obtained; so that
from these results there is no doubt but the darker portion of the
molluskite contains about .35 per cent, of its weight of carbon in an
organized state."
"Now nearly the whole of the shells in the beds of Kentish Rag," Mr.
Bensted remarks, "have their shells open, as if they were dead before
their envelopment in the deposit. And, from the large quantity of
water-worn fragments of wood perforated by Pholades imbedded with them,
it seems probable that this stratum had originally been a sand-bank
covered with drifted wood and shells, thus presenting a very analogous
condition to the phenomenon above described." The gelatinous bodies of
the _Trigoniæ_, _Ostreæ_, _Rostellariæ_, _Terebratulæ_, &c., detached
from their shells, may have been intermingled with the drifted wood in
a sand-bank; while, in some instances, the animal matter would remain
in the shells, be converted into molluskite, and retain the form of the
original, as in the spiral univalve, represented in section, _Lign.
139, fig. 3_.
* * * * *
A microscopical examination of the Maidstone molluskite detects, with
a low power, innumerable portions of the nacreous laminæ of shells,
intermingled with the carbonaceous matter, many siliceous spicula of
Sponges, minute spines of Echinoderms, and fragments of Corals; these
extraneous bodies probably became entangled among the floating animal
matter. A large proportion of the shelly laminæ, examined with a high
power, displays the peculiar structure of the _Terebratulæ_ (see
_Lign. 126, fig. 2a_), of which several species are abundant in
the Kentish Rag.
The dark masses and veins so common in the Sussex and Purbeck marbles
are produced by molluskite. If at the period of their envelopment
the shells were empty, they became filled either with grey marl and
limestone, or with white calcareous spar; but if they enclosed the
bodies of the Mollusks, the soft mass was changed into carbonaceous
matter; and in polished sections of the marble, the _molluskite_
appears either in black or dark brown spots, or fills up the cavities
of the shells. The dark blotches and veins observable in the fine
pillars of Purbeck marble in the Temple Church, London, are produced
by molluskite; and the most beautiful slabs of Sussex marble owe their
appearance to the contrast produced by this black substance in contact
with white calcareous spar.[392]
[392] See a "Memoir on the Carbonized Remains of Mollusca," by the
author. Read before the Geological Society of London, February, 1843;
and published in the American Journal of Science.
Carbon, resulting from animal remains, is of frequent occurrence
in many strata; and the fetid emanations from certain limestones,
upon being broken or rubbed, are attributable to the evolution of
sulphuretted hydrogen, from the animal matter which they contain.
* * * * *
[Sidenote: GEOLOGICAL DISTRIBUTION OF SHELLS.]
Geological Distribution of the Bivalve and Univalve Mollusca.--If the
more rare and splendid organic remains may be regarded as the "Medals
of Creation," the fossil testaceous mollusca, from their durability,
numbers and variety, may be considered as the current coin of Geology.
Occurring in the most ancient fossiliferous strata in small numbers,
and of peculiar types,--becoming more abundant and varied in the
secondary formations,--and increasing prodigiously, both numerically
and specifically, in the tertiary, these relics are of inestimable
value in the identification of a stratum in distant regions, and in
the determination of the relative age of a series of deposits. To the
solution of the former problem the sagacity of the late Dr. William
Smith first suggested their applicability;[393] while the idea, so
happily conceived, and so philosophically candied out, by Sir C. Lyell,
of arranging that heretofore chaotic mass of deposits, termed the
Tertiary, into groups, by the relative number of recent and extinct
species of shells, demonstrated the important aid to be derived from
this class of organic remains, in the determination of some of the most
difficult questions in geological science.
[393] See an interesting memoir of Dr, Smith, from the pen of his
distinguished nephew, Professor Phillips.
Many useful tables have been constructed by Professor Phillips,[394]
Sir C. Lyell, M. Deshayes, M. D'Orbigny, Prof. E. Forbes, and other
eminent observers, to illustrate the geological distribution, in the
several formations, of the genera and species of fossil shells hitherto
described. To the English student, Mr. Morris's "Catalogue of British
Fossils," of which an enlarged edition is in the press, will be the
most valuable for reference. In the works which we have especially
recommended for reference (_ante_, p. 10), figures are given of some of
the characteristic shells from each formation, as follow; commencing
with the most ancient deposits.
[394] A Treatise on Geology; and Art. _Geology_, Encyclopæd.
Metropolitana.
Silurian System. _Ly._ p. 350.
Orthis orbicularis; _Ly._ fig. 409.
------ grandis;--fig. 427.
Terebratula navicula;--fig. 410.
------------ Wilsoni;--fig. 413.
Pentamerus Knightii;--fig, 411.
---------- lævis;--fig. 426.
Atrypa reticularis; fig. 414. _Wond._ p. 786.
Lingula Lewisii; _Ly._ fig. 412.
Strophomena depressa;--fig. 421.
Devonian System. _Ly._ p. 342.
Calceola sandalina; _Ly._ fig. 403.
Stringocephalus Burtini;--fig. 404.
Megalodon cucullatus;--fig. 405.
"The Silurian System," by Sir R. I. Murchison, a splendid work on the
rocks and fossils of the above formations, contains numerous figures
of the shells peculiar to each group of strata; and many other species
are delineated in the Memoir on the Devonian deposits of Devonshire
and Cornwall, by Sedgwick and Murchison, _Geol. Trans. New Series_,
vol. v. plates lii-lvii. A Memoir on the Palæozoic Rocks of Germany and
Belgium, by the same distinguished geologists, is also accompanied by
many figures of fossil shells belonging to the same geological epochs.
_Geol. Trans. New Series_, vol. vi.
See also Prof. M'Coy's "Silurian Fossils of Ireland," and his
Description of the British Palæozoic Fossils in the Woodwardian Museum
at Cambridge, in Prof. Sedgwick's "Synopsis of the Classification of
the British Palæozoic Rocks," of which two Parts are already published.
Carboniferous System. _Ly._ 308. _Wond._ p. 736.
Producta punctata; _Wond._ p. 736.
-------- Martini; _Ly._ fig. 390.
Pleurotomaria flammigera; _Lign._ 136, fig. 4.
Euomphalus pentangulatus; _Lign._ 136, fig. 1.
Natica plicistria; _Lign._ 136, fig. 3.
Spirifera trigonalis; _Wond._ p. 736.
--------- triangularis; _Wond._ p. 736.
--------- glabra; _Ly._ p. 389.
Serpula carbonaria; _Ly._ fig. 375.
Avicula papyracea;--fig. 378.
For the shells of the Mountain Limestone, reference should be made to
the second vol. of Prof. Phillips's "Geology of Yorkshire;" to Prof.
M'Coy's "Carboniferous Limestone Fossils of Ireland;" and to Prof,
de Konick's "Anim. Foss. Belg." The fossils of other portions of the
Carboniferous System are illustrated in Phillips's "Palæozoic Fossils
of Devon;"[395] and in Prestwich's Memoir on Coalbrook Dale (_Geol.
Trans._).
[395] To prevent confusion, it may be necessary to state that Professor
Phillips, in the work referred to, terms the Silurian strata the
"_lower palæozoic_" and the mountain limestone, the "_upper palæozoic_"
Magnesian Limestone and Trias. _Ly._ p. 301.
Producta calva; _Ly._ p. 203, fig. 337. } Permian.
Spirifera undulata;--fig. 338. }
Posidonia minuta;--p. 288, fig. 321. } Triassic
Avicula socialis;--fig. 322. }
Prof. King's elaborate Monograph on the Permian Fossils (published by
the Palæontographical Society) should be consulted by the student.
Lias. _Ly._ p. 273.
Pleurotomaria Anglica; _Ly._ p. 39.
Avicula inæquivalvis; _Ly._ fig. 302.
Plagiostoma giganteum; _Ly._ fig. 303.
Gryphæa incurva; _Lign._ 127.
Oolite. _Ly._ p. 257.
Gryphæa virgula; _Ly._ fig. 268.
Ostrea deltoidea (Kimmeridge Clay);--fig. 269.
Trigonia gibbosa;--fig. 270.
-------- clavellata; _Lign._ 127.
-------- costata; _Lign._ 127.
Nerinæa Goodhallii; _Ly._ fig. 274.
Diceras arietinum;--fig. 275.
Pleurotomaria;--fig. 299.
Terebratula spinosa;--fig_ 297.
----------- digona;--fig_ 283.
Ostrea Marshii;--fig. 300.
Phasianella Heddingtonensis;--fig. 58.
Many of the characteristic shells of the Oolite and Kimmeridge Clay,
are figured in Plates XXII. and XXIII. of Dr. Fitton's Memoir on the
Strata below the Chalk; _Geol. Trans. New Series_, vol. iv.
The fossil shells of the Great Oolite are figured and described by
Messrs. Morris and Lycett, in the Memoirs of the Palæontographical
Society; and valuable Papers on the Brachiopods of the Oolite and Lias,
by Mr. Davidson, have been published by the same Society.
Wealden and Purbeck. _Wond._ vol. i. _Geol. S. E._, _Foss. Tilg.
For._, and _Ly._ p. 225.
Melanopsis; _Wond._ pp. 401 and 404.
Cyclas;--p. 404.
Paludina Sussexiensis;--p. 401.
Neritina Fittoni;--p. 401.
Mytilus Lyellii;--p. 405.
Unio antiquus; _Geol. S. E._ p. 250, fig. 1.
---- compressus;--fig. 2.
---- aduncus;--fig. 3.
---- porrectus;--fig. 4.
Valdensis;--_Min. Conch._ pl. 646, and _Lign._ 131.
Corbula alata; _Ly._ p. 229.
Ostrea distorta;--p. 232.
The shells of the Wealden are also figured by Dr. Fitton, _Geol. Trans.
New Series_, vol. iv. Pl. XXI.
Chalk Formation.
I.--Shanklin, or Lower Greensand. _Ly._ p. 219.
Dr. Fitton's Memoir, previously quoted, contains numerous figures of
the characteristic shells of this division of the Chalk, particularly
of the species which abound in the celebrated Whetstone of Devonshire.
_Geol. Trans. New Series_, vol. iv. Pl. XIII-XVIII. See also Prof. E.
Forbes's Catalogue of Lower Greensand Fossils, in the Quart. Geol.
Journal, vol. i.
II.--Galt and Upper Greensand. _Wond._ p. 307; _Ly._ p. 218.
Inoceramus concentricus; _Wond._ p. 330, fig. 1.
---------- sulcatus;--fig. 3.
Terebratula lyra; _Ly._ fig. 219.
Pecten quinquecostatus;--fig. 203.
Ostrea carinata;--fig. 204.
In Plates XI. and XII. of Dr. Fitton's Memoir, there are figures of
more than twenty characteristic shells of this division of the Chalk.
III.--White Chalk. _Ly._ p. 211, _Foss. South D._, _Geol. S. E._
Some cretaceous species are delineated in _Lign. 125, 126, 128, 129,
130, 138_; and Sir C. Lyell figures other species; but I must refer the
student to the _Foss. South D._, _Geol. S. E._, and Dixon's _Fossils
of Sussex_, as accessible works containing numerous figures of the
fossil shells of the Chalk. Accurate descriptions and representations
of all the British chalk shells, however, are still much required.
Mr. Davidson has done much towards the illustration of our Cretaceous
Brachiopods; and the shells of the Cretaceous strata of the United
States are figured and described in an elegant work by Dr. Morton, of
Philadelphia.
Tertiary Formations.
I.--Eocene. _Ly._ p. 174; _Wond._ p. 226.
II.--Miocene. _Ly._ p. 168.
III.--Pliocene. _Ly._ p. 161.
The specimens figured by Sir C. Lyell have been so carefully selected,
and are so well engraven, as to present a _coup-d'œil_ of the most
characteristic shells of the three grand divisions of the Tertiary
Deposits.
I have reserved for especial mention in this place, the work, which
will afford the student of British fossil Conchology the most important
aid in the identification of specimens, namely, the "_Mineral
Conchology of Great Britain_," by the late eminent naturalist, Mr.
James Sowerby, and continued by his son, Mr. James De Carle Sowerby; in
six volumes 8vo., with several hundred coloured plates. Unfortunately,
this work has long been discontinued; and the rapid progress of
discovery, and the numerous foreign publications on every department
of fossil conchology, almost forbid the hope that it will be resumed
by the present proprietor. Although the high price of this work places
it beyond the reach of many individuals, it will be found in most
libraries of Natural History.
* * * * *
[Sidenote: ON COLLECTING FOSSIL SHELLS.]
On the Collection and Arrangement of Fossil Shells.--The instructions
already given for the collection of corals, echinoderms, &c., will
have familiarized the student with the methods generally adopted,
and render it unnecessary to enter into much detail. The shells in
arenaceous deposits, particularly in those of the Tertiary formations,
are commonly so perfect, as merely to require careful removal: those in
the clays are more fragile, and must be extracted with great caution;
and, when very delicate, should be left attached to the clay or shale.
The specimens extracted entire may be kept either in paper trays, lined
with wadding, or fixed to pieces of card or thin board covered with
paper, by thick gum-water; three or four specimens being attached in
different positions, so as to expose the essential characters, as the
aperture, spire, and back of the univalves, and the hinge, muscular
imprints, &c. of the bivalves. Where only casts remain, search should
be made for an impression of the outer surface of the shell, and a cast
taken of it in wax, kneaded bread, or plaster of Paris. In indurated
clays, sometimes both shells and casts may be obtained; and a specimen
of each should be preserved. Mastic varnish, or solution of gum
tragacanth, delicately applied to fragile shells, tends to preserve
them, and improves their appearance. It is desirable to collect the
same species in various states of growth; the form of the young shell
(as in _Rostellaria ampla_, of Solander) often differing essentially
from that of the adult. It will be found convenient to have trays or
boards of different colours; and to select one tint for the shells
collected from a particular formation, or deposit; for example, the
newer Tertiary may be placed on yellow paper; the older, or Eocene
fossils, on light-blue. It is also desirable to separate the marine
from the fresh-water species.
Shells imbedded in chalk, limestone, &c., often require much labour
to display their more delicate and important characters. For clearing
chalk specimens, a stout penknife, and a few gravers or gouges of
various sizes, will be necessary; and by a little practice, the spines
of the Spondylus (_Lign. 128_), and the beaks and hinge of Inocerami
(_Lign. 129_), &c., may be readily exposed. A small stiffish brush,
used with water, is also serviceable. The shells in compact stone,
as those of the mountain limestone, must generally be cleared with
the hammer and chisel. Common species may be broken out, and, from
several examples, probably one or two will be found perfect; but choice
and rare specimens should not be thus risked; they will amply repay
the trouble of the less expeditious method of chiselling away the
surrounding stone. Casts may be taken in gutta percha, &c.
To determine the names of the specimens that he has collected should be
the next care of the student. No method will so readily initiate the
young collector in fossil conchology, as the careful examination of
a small series of the common species, with their names attached.[396]
By the geological map,[397] the nature of the deposit in which the
locality of the specimens is situated, may be ascertained; and the
remarks previously advanced on the prevailing shells of each formation,
will afford a general idea of the genera to which they belong; and, by
referring to the figures quoted, the specific names may be determined.
[396] Such a series may be obtained, at very little cost, of dealers in
objects of natural history; as, Messrs. Tennant, Sowerby, the British
Natural History Society, &c. See Appendix.
[397] A Geological Map of England and Wales, coloured by Mr. Woodward,
under the direction of Sir R. I. Murchison, has been published by the
Society for the Diffusion of Useful Knowledge, at the low price of
5_s._ Although on a very small scale, and therefore not to be compared
for utility and convenience with that by Prof. Phillips, much less with
Greenough's large map, or with Knipe's, it will be found serviceable.
I subjoin a list of some localities of fossil shells, to direct
research in places which are likely to be productive.
* * * * *
BRITISH LOCALITIES OF FOSSIL SHELLS.
[Sidenote: BRITISH LOCALITIES OF FOSSIL SHELLS.]
Aldborough, Suffolk. The usual shells of the Crag.
Alum Bay, Isle of Wight. Eocene tertiary; marine and fresh-water
shells.
Ancliff. Great variety of minute shells of the Oolite.
Arundel, Sussex. Chalk-pits in the neighbourhood.
Atherfield, Isle of Wight, Shells of the lower beds of the Lower
Greensand, in great variety and abundance.
Aylesbury, Bucks. Kimmeridge Clay: near Hartwell.
Aymestry. _Pentamerus_, and other Silurian shells.
Barnstaple, North Devon. Numerous Devonian shells.
Barton Cliff, Hants. Eocene shells in profusion.
Bedford. Lower Oolite, _Terebratulæ_, _Ostreæ_, _Myadæ_, &c.
Binstead, near Ryde, Isle of Wight. Tertiary: in the stone-quarries,
terrestrial and fresh-water shells, as _Bulimus_, _Helix_,
_Limncæ_, and _Planorbis_.
Blackdown, near Collumpton, Devon. Greensand. Numerous silicified
shells, of great beauty. _Trigonia_, _Venus_, _Corbula_,
_Rostellaria_, &c. &c.
Bognor Rocks, Sussex. Eocene Tertiary. _Vermetus_, _Pectunculus_,
_Pinna_, _Voluta_, &c.
Bolland. Numerous shells of the Mountain Limestone.
Bradford, Wilts. Numerous Oolitic shells. _Avicula._
Bramerton Hill, near Norwich. Shells of the Norfolk Crag.
Brighton. _Strondylus_, _Terebratula_, _Ostrea_, _Pecten_,
_Inoceramus_, &c. Many species in the chalk.
Bromley, Kent. Eocene Tertiary. Oyster conglomerate.
Brook-point, Isle of Wight: about one mile east of the Chine.
Wealden: _Unio valdensis_, _Cyclades_, _Paludinæ_, &c.
Brora, Scotland. Oolite. _Pholadomya_, _Sanguinolaria_, &c.
Calbourn, Isle of Wight. Tertiary. Fresh-water Univalves.
Cambridge. In the Galt and Chalk-marl, the usual shells.
Castle Hill, near Newhaven, Sussex. In the Tertiary strata, on the
summit of the hill. Numerous _Potamides_, _Cyclades_, and other
fresh-water shells, _Ostreæ_, with pebbles.
Chardstock, Devon. The fossils of the Lower Chalk.
Cheltenham. Fine shells of the Oolite and Lias.
Chute, near Longleat, Wilts. Greensand shells, in abundance.
Clayton, near Hurst, Sussex. In Chalk-marl, many rare shells; as,
_Dolium nodosum_ (_Min. Conch._ tab. 326.)
Clifton. Carboniferous Limestone. _Spirifera_, _Producta_, &c.
Coalbrook Dale. Silurian and Carboniferous fossils.
Cork. In the vicinity. Carboniferous limestone shells.
Crich Hill, Derbyshire. The usual shells of the Mountain Limestone.
Cuckfield, Sussex. In the Sandstone and Grit, fresh-water shells of
the Wealden.
Dudley. Profusion of shells of the Silurian strata.
Dundry, near Bristol. Beautiful shells in the Inferior Oolite.
Earlstoke, Wilts. Many shells of the Greensand.
Faringdon, Berks. The usual shells of the Oolite in the Coral Rag,
&c.; and of the Greensand, in the Gravel-pits.
Folkstone, Kent. Galt. _Inoceramus_, _Arca_, _Rostellaria_,
_Dentalium_, &c. Lower Greensand, _Gryphæa_, _Ostrea_, &c.
Gravesend. Beautiful shells of the White Chalk.
Hampstead Cliff, Isle of Wight. Fresh-water Tertiary shells.
Hampton Quarry, near Bath. Abounds in Oolitic shells.
Hartwell, Bucks. On the estate of Dr. Lee, beautiful shells of the
Kimmeridge Clay.
Harwich Cliff, Essex. The Crag shells. _Voluta Lamberti_.
Hastings, Sussex. Fresh-water shells of the Wealden.
Headon Hill, Isle of Wight. Fresh-water Tertiary shells in profusion.
Heddington. Oysters in Kimmeridge Clay (_Ostrea deltoidea_). _Perna_,
_Gervillia_, _Trigonia_, &c.
Highworth, Wilts. Very fine Trigoniæ, and other Oolitic, shells, in
the stone-quarries.
Hollington, near Hastings. Wealden. Fresh-water bivalves, &c.
Holywell, near Ipswich. Shells of the Crag, abundantly.
Hordwell Cliff, Hants. The usual shells of the Eocene deposits, in
immense quantity, variety, and perfection.
Horningsham, near Frome, Wilts. Oxford Clay. _Terebratula_, _Pecten_,
&c. in great numbers.
Horsham, Sussex. Fresh-water shells of the Wealden, in the
stone-quarries.
Humbleton Hill, Sunderland. Permian fossils.
Hythe, Kent. Greensand. _Trigonia_, _Gryphæa_, _Pecten_, &c.
Ilminster, Somerset. _Brachiopoda_, &c. Inf. Oolite and Marlstone.
Ipswich. The usual Crag shells.
Langton Green, near Tunbridge Wells. Wealden. In the sandstone
quarries, _Uniones_, _Cyclades_, &c.
Leckhampton Hill, near Cheltenham. Numerous shells of the Inferior
Oolite and Lias.
Lewes. _Inoceramus_, _Pecten_, and usual shells of the White Chalk
and Chalk Marl.
Ludlow. _Pentamerus_, _Spirifera_, &c. and other Silurian shells.
Lyme Regis. Lias. _Plagiostoma_, _Gryphæa_, _Trochus_.
Malton. Beautiful shells of the Oolite.
Matlock, Derbyshire. The mountain limestone in the vicinity abounds
in the characteristic shells _Leptæna_, _Spirifer_, &c.
Minchinhampton. Numerous shells of the Great Oolite.
Osmington, near Weymouth. Purbeck; fresh-water and marine shells:
Oolite; _Trigonia_, _Gervillia_, _Perna_, _Pholadomya_, and many
other genera.
Portland, Isle of. Oolite. In the stone-quarries immense numbers of
the genera _Trigonia_, _Venus_, _Ostrea_, _Pecten_, &c.
Pluckley, Kent. Lower Greensand. _Trigoniæ_, _Terebratulæ_, &c.
Radipole, near Weymouth. _Trigonia_, _Pholadomya_, &c. in Oxford Clay.
Sandgate, near Margate. In the Greensand, the usual shells.
Scarborough. In the cliffs along the shore, a profusion of Oolitic
and Liassic shells.
Selbourne, Hants. In the firestone, _Ostrea carinata_ and other
characteristic shells.
Shalfleet, Isle of Wight. In tertiary fresh-water limestone, shells
of various genera, as _Bulimus_, _Helix_, _Planorbis_, &c.
Shanklin Chine. Greensand. In the cliffs along the shore,
_Terebratidæ_, _Gryphites_, _Gervilliæ_, and many other shells.
Sharnbrook, Bedfordshire. The usual shells of the Cornbrash and Lower
Oolite.
Sheppey, Isle of. Eocene. London Clay shells, in abundance.
South Petherton, Somerset. _Terebratulæ_, _Pholadomya_, _Ostreæ_,
_Pleurotomariæ_, &c. of the Marlstone.
Stamford, Lincolnshire. Lower Oolite. Univalves and bivalves in
profusion.
Stonesfield, Oxfordshire. _Trigoniæ_ and other shells of the Lower
Oolite.
Stubbington Cliff, near Portsmouth. Eocene shells.
Swanage. In the quarries in the vicinity, the prevailing fresh-water
shells of the Purbeck limestone.
Swindon, Wilts. Oolite. The Portland limestone abounds in the usual
shells of that deposit. _Trigoniæ_, _Gervilliæ_, &c.
Taunton, Somersetshire, (Pickeridge Hill, &c.) _Lima_, _Pecten_, and
other Liassic shells.
Tisbury, Wilts. Beautiful _Trigoniæ_, and other shells of the
Portland Oolite.
Vincent's, St., near Clifton. The rocks abound in the usual shells of
the mountain limestone.
Walton, Essex. Shells of the Crag, in great variety.
Weymouth. The Oxford Clay and other strata in the vicinity contain
great variety of fossil shells.
Whitecliff Bay, Isle of Wight. Eocene. Marine and fresh-water shells.
Worthing. The chalk quarries in the neighbourhood are remarkably
prolific in the usual species; and yield Sphærulites.
Note.--A comprehensive list of the localities for _Lower Palæozoic_
shells, &c. is given by Prof. M'Coy in the second Fasciculus of the
"British Palæozoic Fossils;" and in the little "Stratigraphical List,"
published by Mr. Tennant, reference is carefully made to the localities
for the fossils of every formation.
END OF VOL. I.
R. CLAY, PRINTER, BREAD STREET HILL.
* * * * *
BOHN’S SCIENTIFIC LIBRARY.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
MANTELL’S
MEDALS OF CREATION.
VOL. II.
[Illustration: _Pl. 2_
_J. Dinkel del. G. Scharf lithog._
_Printed by Hullmandel & Walton_]
THE
Medals of Creation;
OR,
FIRST LESSONS IN GEOLOGY,
AND
THE STUDY OF ORGANIC REMAINS.
BY
GIDEON ALGERNON MANTELL, LL.D. F.R.S. V.P.G.S.
PRESIDENT OF THE WEST LONDON MEDICAL SOCIETY, ETC.
AUTHOR OF THE WONDERS OF GEOLOGY, ETC.
[Illustration: INCLINED STRATA OF MILLSTONE GRIT, CRICH HILL.]
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
IN TWO VOLS.--VOL. II.
CONTAINING
Fossil Cephalopoda, Crustacea, Insects, Fishes Reptiles,
Birds, and Mammalia.
WITH NOTES OF GEOLOGICAL EXCURSIONS.
SECOND EDITION, ENTIRELY REWRITTEN.
LONDON:
HENRY G. BOHN, YORK STREET, COVENT GARDEN.
LONDON:
R. CLAY, PRINTER, BREAD STREET HILL.
DESCRIPTION
OF THE
FRONTISPIECE OF VOL. II.
PLATE II.
_Illustrative of the mode of developing Fossil Fishes in Chalk._
Osmeroides Mantelli: a Fossil Smelt; from the _Chalk_, Lewes.
See page 626.
(_One-third natural size._)
Fig. 1.--The two corresponding surfaces of a block of Chalk split asunder. The
irregular oval lines, seen on each surface, are the only apparent indications
that the stone contains an extraneous body.
2.--In this figure the two pieces represented above are shown cemented
together; care having been taken that the oval markings on each
surface were accurately adjusted. The chalk has been chiselled away
in the supposed longitudinal direction of the enclosed extraneous
body, and part of the scaly surface of a fish has been thus brought to
light. A portion of chalk has also been removed towards both ends,
with the view of ascertaining the extent and direction of the fossil;
and at each place indications of its presence are visible.
3.--Represents the specimen completely developed. It proves to be a fish
almost perfect, lying on its back, with the body uncompressed, the
mouth open, the arches and opercula of the gills expanded, and the
dorsal, pectoral, and ventral fins entire. The caudal fin, or tail, is
imperfect. The original is nine inches long, and is one of the most
extraordinary fossil fishes ever discovered. It belongs to the Salmon
family, and is allied to the Osmerus, or Smelt; it is now in the British
Museum. We thus perceive that the oval markings on the surface of
fig. 1 were occasioned by the section of the scales covering the cylindrical
body of the fish (see p. 627). A magnified view of one of the
scales is figured _Lign. 185, fig. 4_, p. 567.
LIST OF LIGNOGRAPHS IN VOL. II.
=======
(_Illustrative of Fossil Zoology._)
LIGN. PAGE
140. Fossil Cuttle-Fish (Kelæno) 447
141. Belemnites, from the Chalk, &c. 451
142. Restored outline of Belemnites 453
143. Restored outline of the Belemnites Puzosianus 454
144. Perfect specimen of Belemnites Puzosianus 455
145. Belemnoteuthis antiquus 460
146. Horny rings and hooks of Belemnoteuthis antiquus 461
147. Osselets of extinct dibranchiate Cephalopoda 463
148. Bellerophon 465
149. Nautilus pompilius in its shell 467
150. Fossil Nautili 470
151. Nautilus elegans 471
152. Nautilus Saxbyi 472
153. Casts of Chambers of Nautilus and Ammonite 473
154. Clymeniæ 473
155. Orthoceratites 475
156. Ammonites from the Cretaceous formation 476
157. Ammonites communis 477
158. Ammonites Jason 479
159. Goniatites 482
160. Shells of the Ammonitidæ 484
161. Hamites, &c. from the Chalk-marl 480
162. Scaphites 488
163. Turrilites 489
164. Turrilites tuberculatus 491
165. Aptychus sublævis 492
166. Fossil impression of Nereis 504
167. Fossil Barnacles and Pholades 507
168. Fossil Crustaceans from the Galt 513
169. Fossil Crustaceans from the Chalk 517
170. Fossil Crustacean from the Oolite 519
171. Archæoniscus Brodiei 521
172. Fossil Limulus, in a Nodule of Ironstone 522
173. Limulus trilobitoides 523
174. Fossil Cyprides 527
175. Trilobites 533
176. Homalonotus delphinocephalus 536
177. Phacops caudatus 538
178. Paradoxides Bohemicus 539
179. Fossil Libellula 551
180. Wings of Neuropterous Insects 553
181. Fossil Wings of Insects 554
182. Insectiferous Limestone 556
183. Fossil Insects from Aix 558
184. A group of Fossil Fish from Aix 562
185. Fossil Scales of Fishes 567
186. Lepidotus 575
187. Amblypterus 576
188. Dorsal Rays of Sharks 578
189. Fossil Teeth of Sharks 585
190. Mandible of Edaphodon Mantelli 589
191. Mandibles of Edaphodon Leptognathus 589
192. Fossil Teeth of Sharks 591
193. Fossil Teeth of Sharks from the Chalk 594
194. Fossil Teeth of Fishes 598
195. Dapedius 603
196. Scales and Fin of Lepidotus Mantelli 605
197. Portion of the Jaw of Lepidotus 606
198. Gyrodus Murchisoni 609
199. Cephalaspis Lyellii 611
200. Cephalaspis Lyellii 611
201. Coccosteus and Pterichthys 613
202. Teeth of Asterolepis 619
203. Smerdis minutus 626
204. Fossil Teeth and Jaws of Fishes 629
205. The Lower Jaw of Iguana 649
206. Fossil Vertebræ of Reptiles 653
207. Dermal Bone of the Swanage Crocodile 658
208. Dermal Bones of Fossil Reptiles 660
209. Eye of Ichthyosaurus 664
210. Teeth of Ichthyosaurus and Plesiosaurus 665
211. Vertebra of Ichthyosaurus 666
212. Pectoral Arch of Ichthyosaurus 667
213. Pectoral Arch of Plesiosaurus 667
214. Paddles of Ichthyosaurus and Plesiosaurus 668
215. Hinder Paddle of an Ichthyosaurus, with its Integument 669
216. Skull and Jaws of Teleosaurus and Steneosaurus 675
217. First Caudal Vertebra of Crocodilus Hastingsiæ 676
218. Portion of Jaw of Megalosaurus Bucklandi 686
219. Tooth of the Megalosaurus Bucklandi 687
220. Jaw of Iguanodon Mantelli 693
221. Lower Tooth of the Iguanodon 694
222. Upper Tooth of the Iguanodon 695
223. Teeth of Iguanodon 696
224. Six Caudal Vertebræ of the Iguanodon 699
225. Left Femur of the Iguanodon 701
226. Bones of the Feet and Claws of Iguanodon 703
227. Mosasaurus Hoffmanni 706
228. Mosasauroid Teeth 707
229. Tooth of Mosasaurus 708
230. Mosasauroid Tooth 710
231. Rhynchosaurus articeps 712
232, 233. Dicynodon lacerticeps 716
234. Dicynodon testudiceps (tooth) 719
235. Telerpeton Elginense 721
236. Telerpeton Elginense (outline) 722
237. Pterodactylus crassirostris 724
238. Chelone Benstedi 733
239. Mandible of a Turtle 734
240. Chelone Bellii 735
241. Tretosternon Bakewelli 737
242. Palæophis Toliapicus 738
243. Cryptobranchus Scheuchzeri 741
244. Archegosaurus Dechenii 747
245. Cheirotherium Kaupii 752
246. Fossil Bird 767
247. Ornithoidichnites from Massachusetts 770
248. Bird-like Footprint, and Impressions of Rain-drops 771
249. Zeuglodon cetoides (teeth) 780
250. Teeth of Zeuglodon 781
251. Teeth of Ruminant 782
252. Leg-bones of Horse, Deer, and Anoplothere 784
253. Elephas Ganesa (skull and tusks) 785
254. Mastodon Tooth 786
255. Anoplotherium (outline) 788
256. Anoplothere and Palæothere (teeth) 790
257. Hyopotamus Teeth 792
258. Tooth of Mastodon Elephantoides 794
259. Elephant Tooth 794
260. Elephant Teeth 794
261. Hippopotamus Teeth 795
262. Rhinoceros Teeth 796
263. Teeth of Horse 797
264. Foot and Tooth of Glyptodon 800
265. Jaws of Phascolotherium and Ampitherium 806
(_Illustrative of Geological Excursions._)
266. Hammers 832
267. Brighton Cliffs 852
268. Section of Brighton Cliffs 854
269. Section at Farringdon 861
270. Section at Derwent Valley 876
271. Crich Hill Quarry 886
272. View of Crich Hill 887
273. Plan of Crich Hill 889
274. Section of Crich Hill 890
275. Diagram Section of Crich Hill 895
TABLE OF CONTENTS.
~~~~~~~~~~
VOL. II.
Description of the Frontispiece of Vol. II. p. v.
List of Lignographs in Vol. II. vii.
Contents of Vol. II. ix.
Chapter XII.--Fossil Cephalopoda, 447. Fossil Dibranchiate
Cephalopods, 450. Belemnites, 451. Belemnitella, 457.
Belemnoteuthis, 459. Beloptera, 463. Geoteuthis, 463. Bellerophon
and Argonaut, 465. Fossil Tetrabranchiate Cephalopods, 466.
Nautilus, 467. Clymenia, 473. Orthoceras, 474. Ammonitidæ, 476.
Ammonites, 478. Goniatites, 482. Ceratites, 483. Crioceras, 483.
Ancyloceras, 484. Toxoceras, 485. Hamites, 485. Ptychoceras, 485.
Baculites, 486. Scaphites, 487. Turrilites, 489. Aptychus, 491.
Geological Distribution of the Fossil Cephalopoda, 492. On the
Collecting British Fossil Cephalopoda, 496. British Localities of
Fossil Cephalopoda, 499.
Chapter XIII.--Fossil Articulata, 503. Annelida, 503. Serpula, 505.
Cirripedia, 505. Calamy, 506. Lepadidæ, 508. Crustacea, 508.
Fossil Crabs, 511. Notopocorystes, 514. Fossil Lobsters, 515.
Enoploclytia, 516. Isopodous Crustaceans, 520. Entomostraca, 522.
Limulus, 522. Eurypterus, 524. Pterygotus, 525. Dithyrocaris, 525.
Ceratiocaris, 525. Hymenocaris, 526. Estheria, 526. Leperditia,
526. Beyrichia, 526. Ostracoda, 526. Cypris, 527. Cythere, 531.
Cypridina, 532. Trilobites, 532. Calymene, 535. Homalonotus,
536. Asaphus, 536. Isotelus, 537. Bumastus, 537. Ogygia, 537.
Phacops, 538. Trinucleus, 538. Paradoxides, 538. Brontes, 539.
Geological Distribution of Crustaceans, 542. On Collecting Fossil
Crustaceans, 544. British Localities of Fossil Crustaceans,
546. Fossil Insects, Scorpions, and Spiders, 547. Insects, 547.
Arachnida, 550. Fossil Scorpion, 550. Fossil Spiders, 550. Fossil
Insects, 551. Neuroptera, 551. Libellulidæ, 551. Corydalis, 552.
Panorpa, 553. Coleoptera, 554. Curculio, 555. Purbeck Insects,
556. Aix Insects, 557. Œningen Insects, 559. Fossil Larvæ of
Phryganea, 559. On Collecting Fossil Insects, 560.
Chapter XIV.--Fossil Ichthyology; comprising the Sharks, Rays, and
other Placoid Fishes, 562. Fishes, 562. Scales of Fishes, 566.
Fins of Fishes, 569. Teeth of Fishes, 570. Skeletons of Fishes,
572. Ichthyodorulites, 576. Hybodus subcarinatus, 580. Fossil
Teeth of Fishes, 582. Cestracion, 584. Acrodus,584. Ptychodus,
585. Psammodus, 587. Ceratodus, 587. Edaphodon, 588. Hybodus, 591.
Sharks with cutting Teeth, 592. Carcharodon, 593. Hemipristis,
593. Lamna, 594. Notidanus, 595. Corax, 595. Fossil Vertebra of
Sharks, 596. Squaloraia, 596. Pristis, 597. Rays, 597.
Chapter XV.--Fossil Ichthyology; comprising the Ganoid, Ctenoid, and
Cycloid Fishes, 600. Amblypterus, 601. Palæoniscus, 601. Dapedius,
603. Lepidotus, 604. Pycnodus, 607. Gyrodus, 608. Cephalaspides,
610. Cephalaspis, 611. Pterichthys, 612. Coccosteus, 614. Fossil
Sauroid Fishes, 615. Lepidostei, 616. Sauroidei, 617. Cœlacanthi,
618. Macropoma, 620. Coprolites, 621. Cololites, 621. Dercetis,
622. Fossil Ctenoid Fishes, 623. Beryx, 624. Smerdis, 625. Fossil
Cycloid Fishes, 625. Osmeroides, 626. Saurocephalus and Saurodon,
628. Hypsodon, 630. Enchodus, 630. Ichthyolites of recent
Species, 631. Ichthyopatolites, 632. Geological Distribution of
Fishes, 632. On Collecting and Developing Fossil Fishes, 635.
Microscopical Examination, 639. British Localities of Fossil
Fishes, 640. Foreign Localities, 641.
Chapter XVI.--Fossil Reptiles; comprising the Enaliosaurians and
Crocodiles, 643. The Age of Reptiles, 644. Classification of
Reptiles, 646. Teeth of Reptiles, 646. Lower Jaw of Reptiles, 651.
Vertebræ, 651. Ribs, 656. Extremities, 657. Dermal Bones, 657.
Dermal Bones of Hylæosaurus, 659. Dermal Spines of Hylæosaurus,
661. Horn of Iguanodon, 661. Enaliosaurians, 662. Ichthyosaurus,
663. Paddle and Skin of Ichthyosaurus, 668. Plesiosaurus, 671.
Pliosaurus, 673. Crocodilians, 674. Swanage Crocodile, 677.
Pœcilopleuron, 679. Teleosaurus, 679. Streptospondylus, 680.
Cetiosaurus, 682. Polyptychodon, 683.
Chapter XVII.--Fossil Reptiles; comprising the Dinosaurians,
Lacertians, Pterodactyles, Turtles, Serpents, and Batrachians,
684. Dinosauria, 684. Megalosaurus, 686. Hylæosaurus, 688.
Iguanodon, 691. Jaw and Teeth of Iguanodon, 693. Vertebra:
of Iguanodon, 698. Extremities of Iguanodon, 700. Length of
Iguanodon, 702. Lacertian Reptiles, 705. Mosasaurus, 705.
Leiodon, 709. Geosaurus, 711. Raphiosaurus, 711. Delicious,
711. Rhynchosaurus, 712. Thecodontosaurus and Palæosaurus, 713.
Dicynodon, 714. Telerpeton, 720. Pterosauria, 723. Chelonia, 726.
Fossil Turtles and Tortoises, 729. Fossil Marine Turtles, 732.
Chelone Benstedi, 732. Chelone Bellii, 734. Fossil Fresh-water
Tortoises, 736. Ophidia, or Serpents, 738. Batrachia, 739.
Batracholites, 740. Labyrinthodon, 741. Archegosaurus, 745.
Parabatrachus, 746. Dendrerpeton, 746. Ichnolites, 749. On
collecting the Fossil Remains of Reptiles, 753. British Localities
of Fossil Reptiles, 756.
Chapter XVIII.--Ornitholites, or Fossil Birds, 759. Osteological
Characters of Birds, 760. Fossil Birds of the Pleistocene Epoch,
763. Fossil Birds of the Older Tertiary Deposits, 765. Fossil
Birds of the Wealden, 768. Ornithoidichnites, 768. On collecting
the Fossil Remains of Birds, 773.
Chapter XIX.--Fossil Mammalia, 775. Classification of Mammalia,
776. Fossil Cetacea, 777. Otolithes of Whales, 778. Brighton
Fossil Whale, 778. Zeuglodon Cetoides, 779. Fossil Ruminants,
782. Pachydermata, 785. Fossil Elephants and Mastodons, 785.
Dinotherium, 787. Cuvierian Pachydermata, 789. Teeth of Mammalia,
793. Fossil Horse, 796. Fossil Edentata, 798. Megatherium,
798. Glyptodon, 799. Mylodon, 800. Fossil Rodents, 802. Fossil
Marsupials, 803. Triassic Mammalian Teeth, 805. Fossil Mammalia of
Stonesfield, 805. Fossil Carnivora, 807. Kent’s Hole, 810. Fossil
Seals, 812. Fossil Insectivora. 812. Fossil Bats, 813. Fossil
Quadrumana, or Monkeys, 813. Fossil Ape of France, 814. Fossil
Monkey of the Sub-Himalayas, 814. Fossil Monkey of South America,
814. Fossil British Monkeys, 815. Fossil Human Bones, 815. On
collecting and developing Fossil Remains of Mammalia, 815. British
Localities of Fossil Mammalia, 818. Bone-caves in Franconia, 820.
Retrospect, 822.
Appendix to Part III., 826.
PART IV.--Notes of Excursions, in Illustration of the Mode of
Investigating Geological Phenomena, and of Collecting Organic
Remains, 827.
Chapter XX.--General Instructions for the Collection of Specimens of
Rocks and Fossils, 831.
Chapter XXI.--Excursions illustrative of the Geological Character and
Organic Remains of the Tertiary Deposits of the London Basin, 837.
Excursion to the Isle of Sheppey, 838. Excursion to Bracklesham
Bay, 844. Notes for an Excursion to examine the Tertiary Strata of
the Isle of Wight, 847.
Chapter XXII.--Notes for a Geological Excursion from London to
Brighton, 849. A Stroll from Brighton to Rottingdean, 852.
Chapter XXIII.--Geological Notes of various Places on the Line of the
Great Western Railway; illustrative of the Oolite, Lias, &c. from
London to Clifton, 859. Farringdon, 859. Swindon, 862. Caine and
Chippenham, 863. Bath and Bristol, 864. Clifton, 864.
Chapter XXIV.--Excursion to Matlock and its Vicinity, 867. Geological
Position of Matlock Dale, 871. A Walk to the Incrusting Springs,
872. Visit to the Cavern of the High Tor, 875. Geological
Formations of Derbyshire, 878. Excursion to Crich Hill, 880. Notes
for a Geological Excursion by Bonsal Valley, and Wirksworth, to
Middleton Moor and Stonnis, 894.
Chapter XXV.--Notes for a Geological Excursion to Charnwood Forest;
by Leicester, Mount Sorel, Swithland and Woodhouse, and Bardon
Hill to Whitwick, 898.
List of Dealers in Fossils and Minerals, &c. 904.
General Index, 909.
THE
MEDALS OF CREATION.
⎼⎼⎼⎼⎼◆⎼⎼⎼⎼⎼
CHAPTER XII.
FOSSIL CEPHALOPODA; COMPRISING THE BELEMNITIDÆ, NAUTILIDÆ, AND
AMMONITIDÆ.
[Illustration: Lign. 140. Fossil Sepia or Cuttle-Fish: 1/3 _nat._
(_M. D’Orbigny._)
_Solenhofen._
(Kelæno[398] speciosa. _Count Münster._)
The impression of the body, head, and arms, with their clasps.]
[398] _Kelæno_ (one of the Furies) = Acanthoteuthis (Wagner); probably
identical with Belemnoteuthis, which also has ten sub-equal arms.--_Mr.
Woodward_.
The molluscous animals named _Cephalopoda_ (from their organs of
prehension being arranged around the upper part of the body) are
the most ancient, numerous, and interesting of this division of
animated nature; and their fossil remains comprehend the most varied
and striking forms of extinct beings that occur in the sedimentary
strata, from the earliest Secondary to the latest Tertiary formations.
The living species are but a feeble representation of the countless
myriads which swarmed in the ancient seas; yet they afford important
assistance in developing the characters of the numerous extinct genera,
whose relics abound in the strata, and will continually be presented to
the observation of the collector. It is therefore necessary to enter
somewhat in detail on the structure of these beings, that the student
may obtain a correct idea of the nature of the curious fossils to which
the mineralized remains of the durable parts of these animals have
given rise, and whose origin has but lately been correctly ascertained.
The body of these mollusca is either enclosed in a shell, as in the
_Nautilus_, or contains a calcareous or cartilaginous part, as in
the _Sepia_, or cuttle-fish; they have a distinct head, and eyes as
perfect as in the vertebrate animals; complicated organs of hearing;
and a powerful manducatory apparatus, surrounded by arms serving for
prehension. They have below the head a tube which acts as a locomotive
instrument to propel the animal backwards, by the forcible ejection
of the water that has served the purposes of respiration, and which
can be thrown out with considerable force by the contraction of the
body. The figures 1 and 6, _Lign. 142_, are views of a naked (that is,
_shell-less_) cephalopod, showing the arms, eyes, and a pair of fins,
for swimming. The Cephalopoda, thus endowed with powerful organs of
locomotion, traverse the seas unrestricted, and are seen in groups of
myriads in the midst of the ocean, and only appear periodically near
the shores. Their fossil remains consist of--
1st. The external shells; which are generally symmetrical, and either
straight (as in _Orthoceras_, _Lign. 155_); arched or bent (as in
_Crioceras_, _Lign. 160_); spiral (as in _Turrilites_, _Lign. 163_); or
involute,[399] and simple (as in the _Argonaut_), or divided, by smooth
or foliaceous partitions, into chambers or air-cells, connected by a
hydraulic tube or siphuncle (as in _Nautilus_, _Lign._ 149 and 150, and
_Ammonites_, _Lign._ 156 and 157).
[399] _Involute_, as applied to the shells of Cephalopoda, implies that
the inner whorls are embraced by the outer turn or whorl; _convolute_,
the inner turns apparent, or exposed; _evolute_, the whorls coiled in
one plane, but not touching each other; _revolute_, the extremities
bent inwards.
2dly. The internal horny or calcareous support, called _osselet_, and
its appendages.[400] (_Lign. 143._)
[400] The _bone_ or _shell_ of the Cuttle-fish, the friable part of
which, reduced to powder, forms _pounce_, is the _osselet_ of that
cephalopod.
3dly. The ink-bladder, with its inspissated contents, termed _sepia_.
4thly. The mandibles of the mouth, or beaks, called _Rhyncholites_.
(_Lign. 150_, _fig._ 1.)
5thly. The soft parts of the animal in the state of molluskite;
impressions of the head and tentacula, and remains of the clasps or
curved hooks of the arms of some species (see _Lign._ 140 and 145).
These several parts are generally found separate, but they sometimes
occur in their proper relative position, and from such examples the
nature of the original may be determined.
The Cephalopoda[401] are divided into two orders, according to
the number of their organs of respiration, or gills; namely,
the _Dibranchiata_, or those which have two gills, (called also
_Acetabulifera_, from their arms being furnished with rows of little
cups or suckers;) and the _Tetrabranchiata_, which have four gills, or
branchiæ, and very numerous arms without suckers.
[401] The best systematic account of the Cephalopoda and Gasteropoda,
both recent and fossil, yet published, is contained in the first part
of the very valuable Manual of Mollusca, by Mr. S. P. Woodward, of the
British Museum.
[Sidenote: FOSSIL CEPHALOPODA]
FOSSIL DIBRANCHIATE CEPHALOPODA.
The _Argonaut_, or Paper Nautilus, whose elegant fragile shell is too
well known to require description, is the only living genus of this
Order, in which the animal is protected by a hard calcareous external
covering. This shell is symmetrical, and convoluted on a vertical
plane, and consists of but one cavity or chamber. The other genera
are naked, and possess an internal chambered shell (as in the recent
_Spirula_), or some modification of such an apparatus. The last chamber
or cell of these enclosed shells is too small to admit any part of the
body of the animal; a character by which the fossil species of this
Order may be distinguished from those of the other order. Others have
a horny or calcareous osselet, as the bone of the Cuttle-fish, and pen
of the Calamary or Sea-pen (see _Bd._ pl. 28); and in an appendage of
this kind a conical chambered shell is contained in many of the fossil
genera, hereafter to be noticed. These animals have eight arms, with
the addition in some genera of two long tentacula, which are furnished
with rows of suctorial disks or cups, called _acetabula_ (see _Lign.
142, figs. 1, 6_).
These naked Cephalopoda, devoid of any external defence, possess a very
extraordinary means of escape from their enemies. They are furnished
with a bag or bladder, containing a dark fluid resembling ink in
appearance, which they have the power of ejecting into the surrounding
water upon the approach of danger; and by the obscurity t us induced,
they foil the pursuit of their adversaries: the Nautilus and other
cephalopods, protected by a large external shell, are destitute of such
an apparatus. The deep brown colour, _sepia_, was formerly prepared
from the fluid of the ink-bags of different species of Cuttle-fish; a
similar substance secreted by extinct naked Cephalopoda, as we shall
presently demonstrate, is found in a fossil state. These preliminary
remarks on the organization of the recent animals will prepare us for
the investigation of the extinct species. We will first notice those
remarkable fossils, called _Belemnites_, or thunder-stones.
[Illustration: Lign. 141. Belemnites: 1/2 _nat._ _Chalk and Oolite._
Fig. 1.--Belemnitella mucronata. _Chalk._ _Brighton._ On the
right of the figure is a view of the aperture, and a transverse
section.
2.--Portion of a Belemnite, containing the internal conical
chambered shell, called _phragmocone_. _Oolite._
3.--Belemnitella quadrata. Beauvais, France. The quadrangular cavity
is shown in the upper figure on the left. (_M. D’Orbigny._)
4.--Belemnites dilatatus. _Lower Greensand_ (_Néocomien_). _France._
]
[Sidenote: BELEMNITES]
Belemnite (from a supposed resemblance to the head of a dart or
javelin). _Lign._ 141 to 144. Among the innumerable relics of an
earlier world, which swarm in the sedimentary deposits, there are
perhaps no fossil bodies that have excited more curiosity, and given
rise to so many fruitless conjectures as to their nature and origin,
as the Belemnites.[402] These are long, cylindrical, or fusiform
fossils, more or less pointed at one extremity, and having at the
other and larger end a conical cavity, which is either occupied by a
chambered shell, or filled up with the material in which the fossils
are imbedded. Their substance is like fibrous calcareous spar, varying
in colour from a dark brown to a light amber; many are transparent,
others nearly opaque. When broken transversely they present a radiated
structure (_Lign. 141, fig. 1_) and a minute central cavity, or axis,
is seen to extend through the whole length of the solid portion of the
stone (see _Lign. 142, fig. 5._). A longitudinal section (_Lign._
142, _figs._ 4 and 5) shows the conical cavity in the upper part, and
that the shaft consists of a series of concentric layers. Such are the
characters of these fossils in the examples of most frequent occurrence.
[402] See Park. Org. Rem. vol. iii. p. 122.
The Belemnites vary in size from the small, delicate, transparent
species, _Lign._ 142, _figs._ 3 and 4, to massy opaque specimens,
several inches in circumference, and from ten to twenty inches in
length. They present also considerable variety of form; some are
regularly cylindrical, as in _Lign. 141 fig. 1_; others broad and
flattened, as in _fig. 4_; or subfusiform, as in _Lign._ 142, _figs._ 3
and 4. The small end is slender and pointed in some belemnites, and in
others is obtuse, or rounded, with a projecting point. In many there is
a longitudinal groove or furrow on the ventral aspect; and some species
have a furrow on each side, as in that represented in _Lign. 142,
fig. 2_.
But the fossils above described are only a part of the original
structure of the Belemnite. When in a perfect state, the cavity seen in
_Lign. 142, fig. 5_, is occupied by a chambered conical shell, called
the _phragmocone_, composed of a series of shallow concave cells, of a
nacreous or pearly substance, which are pierced by a siphuncle at the
margin; see _Lign. 141, fig. 2_.
The parts of the Belemnite at present known consist of--
1st. The spathose osselet, or _guard_, having at the larger end a
conical cavity, called the _alveolus_, as in _Lign. 141, fig. 1_, and
_Lign. 142, fig. 5_.
2dly. A conical, chambered pearly shell, termed the _phragmocone_,
which is situated in the _alveolus_ (as in _Lign. 141, fig. 2_).
[Illustration: Lign. 142. Belemnites: 1/2 _nat._
Fig. 1.--A front view of the supposed animal of the Belemnite, by
_M. D’Orbigny_. _b._ denotes the osselet, to the base of which
the _Belemnite_, _a_, is attached.
2.--Belemnites bipartitus; the figure below shows the form
of the aperture. _Neocomian Formation._ _France._ (_M.
D’Orbigny._)
3.--Belemnites Listeri (G. A. M.); _from the Galt._ _Ringmer._
4.--A longitudinal section of B. Listeri.
5.--Belemnites semicaniliculatus: a longitudinal section;
the figure below is the aperture of the _alveolus_. _From the
Firestone (Craie tufeau) of France._
6.--A side view of fig. 1.
]
3dly. The horny prolongation of the _capsule_ (the outer investment of
the _guard_), called the _receptacle_, as in _Lign. 143_.
4thly. The _ink-bag_, and its inspissated fluid, _sepia_; (_Bd._ pl.
44′, figs. 7, 9.)
[Illustration: Lign. 143. The structure of the sherry parts of the
Belemnites Puzosianus.
_Oxford Clay._ _Christian Malford._ (1/4 _nat. size_.)
_a, a._ The dorsal basilar processes of the phragmocone.
_b, b._ Upward extension of the attenuated osselet.
_c._ Siphunculus.
_d._ Phragmocone: the transverse lines indicate the septa.
_e._ The capsule or outer investment of the guard.
_f._ The distal part of the phragmocone.
_g._ The alveolus or cavity in the guard.
_h._ Vertical section of the guard.
_i._ The solid part of the rostrum or guard.
_k._ The sulcus or groove on the ventral aspect of the rostrum.
_l._ Shows the continuation of the capsule, in section, continued from e.
_m._ Diverging parallel striæ observable between the dorsal processes of
the phragmocone.
_n._ Transverse section of half the diameter of the radiated structure.
]
[Illustration: Lign. 144. Very perfect specimen of Belemnites
Puzosianus.
_Oxford Clay._ _Christian Malford, Wilts._ (1/6 nat. size.)
_a, a._ Basal processes of the phragmocone.
_b._ The phragmocone.
_c._ The rostrum or guard of the osselet, containing the apex of the
phragmocone in its upper part.
]
The invariably radiated crystalline structure of the Belemnite has
evidently resulted from the peculiar organization of the original
osselet, which is formed of thin concentric laminæ, of very minute
prismatic trihedral fibres, arranged at right angles to the planes of
the successive layers.[403]
[403] The Belemnitic shell presents the same arrangement of its
constituent layers as the Pearl-mussel, Pinna, and other _Aviculidæ_,
viz. the outer layer is prismatic-cellular, the inner nacreous: the
first is formed by the free margin of the mantle, the second by the
visceral ("peritoneal") part of the mantle.--_Mr. Woodward._
From the obvious analogy of the structure above demonstrated with that
of the recent dibranchiate Cephalopoda, several eminent naturalists
inferred that the animal of the Belemnite was closely related to the
existing types; and the late Mr. Miller, in a communication to the
Geological Society of London, gave a restored figure of the original,
which, as modified by M. D’Orbigny, is represented _Lign._ 142, _figs._
1 and 6. The indefatigable and successful researches of the Rev. Dr.
Buckland have confirmed the general correctness of this restoration.
In the Lias of Dorsetshire two specimens of the Belemnite, with its
chambered shell and horny or pearly receptacle, still retaining the
ink-bag and its contents, have been discovered, and were figured in
the Br. Treatise (_Bd._ pl. 44′, 44″). A third specimen, showing the
ink-bag, is in the British Museum.
The ink-bag of the Belemnite is very small, as might be expected, from
the extent to which it is protected by a chambered shell. The mandibles
or beaks of the Belemnite are supposed to have been horny, as in the
other naked Cephalopoda; since no calcareous beaks have been found
associated with their remains.
"The Belemnite having the advantage of its dense, but well-balanced
internal shell, must have exercised the power of swimming backwards
and forwards, which it possessed in common with the modern decapod
(_ten-armed_) Dibranchiata, with great vigour and precision. Its
position was probably more commonly vertical than in its recent
congeners. It would rise swiftly and stealthily to infix its claws
in the belly of a supernatant fish, and then perhaps as swiftly dart
down, and drag its prey to the bottom and devour it. We cannot doubt
at least but that, like the hooked Calamaries of the present seas, the
ancient Belemnites were the most formidable and predacious of their
class."--Owen.
The Belemnites of the oolitic limestones frequently contain the
phragmocone, either filled with calcareous spar, or with its cells
empty. In the clays the horny sheath or receptacle is sometimes found
pressed flat and extending above the alveolus of the osselet, and has
often a thin coat of nacre of a pearly lustre, but it is more commonly
detached.
The Belemnites abound in the Lias, Oolite, and Chalk, and have not
been discovered in any other deposits; there are nearly thirty British
species, some of which are restricted to the Chalk, and others to the
Oolite and Lias.
A few characteristic forms are represented, _Lign._ 141 and 142, in
order to illustrate the three groups which, according to M. D’Orbigny,
are peculiar to the grand divisions of the Cretaceous formation.
1. Belemnitella mucronata. _Lign. 141, fig. 1._--The name
_Belemnitella_ is given to those Belemnites which have a slit, or
crevice, on the anterior margin of the alveolus or cavity, and two
lateral impressions. The surface is sometimes granulated, and often has
vascular markings, produced by the investing integument of the living
animal. The form of the aperture is shown in the middle dextral figure;
and the radiated structure, as seen by a transverse section, in the
sketch.
This species is abundant in the _White Chalk_, particularly in certain
localities in Norfolk and Devonshire. It is more frequent in the chalk
of Kent than in that of Sussex; and in the cretaceous strata around
Brighton, than in those near Lewes. I have never been able to detect
the least vestige of the phragmocone, or chambered shell, in the
alveolus. This Belemnite is occasionally imbedded in flint nodules; and
such examples possess the calcareous crystalline structure of the chalk
and limestone specimens. In the chalk of Ireland, the Belemnites which
have been corroded, or perforated by marine borers (_cliona_), are
often injected with flint; and if the calcareous substance be removed
by immersion in dilute hydrochloric acid, exquisite siliceous casts
may be obtained (see also page 403). It is not unusual to find flints
with a cavity, occasioned by the solution and removal of the calcareous
guard, and having a siliceous conical cast of the alveolus, occupying
the upper part of the interspace. The reader will recollect that the
pulley-stones of the Derbyshire Encrinites were produced by a similar
process (see p. 285, vol. i.).
The American cretaceous sands abound in a species of Belemnitella,
nearly related to _B. mucronata_.
2. Belemnites Listeri. _Lign. 142, fig. 3._--This small elegant
Belemnite has two lateral grooves, and is generally as transparent as
amber; it has frequently a nacreous or calcareous pellicle partially
investing the guard. It seldom exceeds two inches in length. It is
abundant in, and peculiar to, the Galt, or blue marl of the Chalk, and
is constantly associated with the Inocerami, previously described as
common at Folkstone, Bletchingley, Ringmer, and other localities of
that deposit. The Red Chalk of Norfolk contains the same species (_Min.
Conch._ tab. 589).
3. Belemnites dilatatus. _Lign. 141, fig. 4._--This species is
distinguished by its flattened form, and by the longitudinal furrow
being situated on the margin opposite to the siphuncle of the
phragmocone, instead of being on the same side, as is most usual. It is
supposed by M. D’Orbigny to be characteristic of the Neocomian beds, or
lowermost division of the Shanklin Sand.
4. The Chalk-marl contains a Belemnite of a more elongated form than
those above described, the apex gradually tapering to a point, with a
slight double furrow on each side. It is named _B. lanceolatus_ (_Sow.
Min. Conch._ tab. 600, figs. 8, 9), and is very common in the marl-pits
at Steyning, Clayton, and Hamsey, in Sussex.
At the base of Golden Cap Hill, near Charmouth, there are two strata
of marl-stone observable on the shore, which are literally paved with
Belemnites. Great numbers of these fossils have Serpulæ and other
extraneous shells attached to them, a proof that the ink-bags and other
soft parts of the mollusks had decomposed, and that the guards had lain
uncovered at the bottom of the sea.
M. De Koninck has discovered in the Devonian limestone of Belgium, at
Couvin and Visé, a small fossil body which closely resembles in form
and structure the rostrum or guard of a belemnite; it is, however, too
fragmentary to admit of positive detemination.[404]
[404] Bulletin del’Académie Roy ale de Bruxelles, tome x. No. 3. p. 207.
[Sidenote: BELEMNOTEUTHIS]
Belemnoteuthis[405] (J. C. Pearce). _Lign. 145._--Within the last few
years much additional knowledge has been obtained regarding the nature
of the extinct Cephalopoda, by the discovery in the Oxford clay, at
Christian Malford, not only of several examples with the receptacle and
ink-bag in their natural relative positions, but also with the remains
and impressions of the mantle, body, tentacula with their hooks, and
the fins!
[405] For the history of this interesting Cephalopod consult Phil.
Trans. 1848, and 1850; Ann. Nat. Hist. June 1850; Petrif. p. 459, &c.
[Illustration: Lign. 145. Belemnoteuthis antiquus. (_Pearce._)
_Oxford Clay._ _Christian Malford._ (1/2 _nat. size_.)
_a._ The uncinated arms and tentacles.
_b._ Remains of the head and eyes.
_c._ The mantle, with indications of fins.
_d._ The pigmental sac or ink-bag.
_e._ The osselet: the transverse lines indicate the septa of the
phragmocone, which is covered by a horny sheath or capsule.
_f._ The solid terminal apex of the osselet.
]
[Sidenote: BELEMNOTEUTHIS ANTIQUUS]
Certain argillaceous strata of the Oolite, as well as of the Lias,
appear to have been peculiarly favourable for the preservation
of the muscular tissue and integuments, and in many specimens of
Belemnoteuthis, the arms, the large sessile eyes, the funnel, a great
proportion of the muscular parts of the mantle, remains of the two
lateral fins, the ink-bladder and duct, and the phragmocone, are well
displayed, as in the beautiful example, _Lign. 145_, for the drawing
of which I am indebted to S. P. Woodward, Esq., of the British Museum.
(See also _Lond. Geol. Journ._ pl. xv. and xvi.)
[Illustration: Lign. 146. Horny rings and hooks of Belemnoteuthis
antiquus.
Fig. 1, 3.--Detached hooks (_natural size_).
2.--Three hooks with attached horny rings: from a specimen in
the possession of Mr. Cunnington.
4.--Part of one of the arms, showing four hooked spines.
5.--Transverse section of the distal part of the osselet of
Belemnoteuthis, exposing the apex of the chambered shell in
the centre, surrounded by the radiated osselet, _a_
(_magnified four diameters_).
]
From the extraordinarily perfect condition of the Belemnoteuthis
here figured, which of itself exemplifies the essential parts of
its structure, a brief description will suffice. The body is of an
elongated form, with a pair of lateral fins, two large sessile eyes,
eight uncinated arms, and a pair of armed tentacles; each arm was
furnished with from twenty to forty pairs of hooks, placed alternately.
Like the Sepia it had a pigmental sac or ink-bag, which is generally
found filled with the inspissated secretion. The inferior part of the
body is of a conical form, and contains a brown horny osselet, with a
siphunculated phragmocone, that terminates in a guard or rostrum of a
fibrous structure.
[In the recent genus _Onychoteuthis_, the tentacles alone are armed
with claws; _Enoploteuthis_ has claws both on the arms and on the
tentacles, but the latter are long and feeble, and the hooks are
confined to their extremities. The extinct _Belemnoteuthis_ (like the
_Acanthoteuthis_ of Solenhofen, _Lign. 140_) had eight nearly equal
arms, the dorsal pair being rather smaller than the rest; each arm
was furnished with twenty to forty pairs of hooks, forming a double,
alternating row. The tentacles were not longer than the arms, and like
them had a double series of hooks extending from their bases to the
points. In all essential points of structure, the Belemnoteuthis is
most nearly related to the Calamaries (_Teuthidæ_), but, in consequence
of the prolongation of its pointed shell posteriorly, the fins
become lateral (as in _Sepiola_ and _Sepia_), instead of terminal.
Whilst the complicated (chambered) structure of its shell, and the
peculiar character of the _tentacles_, show that it must be regarded
as a type distinct from and equal in importance to the Calamaries.
It cannot be doubted that the _Belemnite_ and _Conoteuthis_ present
similar conditions of the soft parts; and the four genera will form
the Family Belemnitidæ. The normal position of these animals in the
sea is horizontal, whilst that of the Nautiloid genera must have been
vertical, with the head downwards.--_Mr. Woodward._]
The fossils which have afforded this unexpected and highly interesting
illustration of the nature of the extinct animals of this Order
have been obtained by closely examining the shales in which they
abound, and, before removing the solid osselet, carefully searching
the surrounding stone for traces of the more perishable parts. The
attention of the collector can scarcely be too often directed to the
necessity of examining the surrounding matrix before extricating a
fossil from its bed.
[Illustration: Lign. 147. Osselets of extinct dibranchiate Cephalopoda.
(_Woodward_, _Manual_, p. 76, pl. 1 & 2.)
Fig. 1.--Belosepia sepioides; 1/2 _nat._ _Eocene._ _Bracklesham._
2.--Spirulirostra Bellardii; 2/3 _nat._ _Miocene._ _Turin._
3.--Beloteuthis subcostata; 1/4 _nat._ _Lias._ _Wirtemberg._
4.--Beloptera belemnitoides; 2/3 _nat._ _Eocene._ _Bracklesham._
]
[Sidenote: BELOPTERA]
Beloptera. (_Bd._ pl. xliv. _fig._ 15. _Min. Conch._ tab. 591.)--Under
this name Mr. Sowerby figures and describes a very curious fossil, from
the London Clay at Highgate, which seems to hold an intermediate place
between the Cuttle-fish and the Spirulirostra. The guard, which is of
an oblong form, with an obtuse apex, has the structure of the osselet
of the Sepia, and contains in its upper part a phragmocone, the cells
of which are very narrow. In strata of the same age, in France, three
species have been discovered by M. Deshayes. I allude to these shells,
that the attention of the collector may be directed to the search after
other examples in our tertiary deposits.
Fossil Calamary, or Squid. Geoteuthis.[406] (_Bd._ pl. xxviii.
xxix.)--The common Calamary (_Loligo vulgaris_) is so often seen on our
shores, that its general aspect must be familiar to all who frequent
the sea-side. In this animal, the osselet, or internal support, is a
cartilaginous elongated body, which, from its form, is called Sea-pen
(_Bd._ pl. xxviii.); and even this delicate structure is found in
a fossil state. In the Lias of Lyme Regis, Miss Mary Aiming first
discovered specimens of _Sea-pens_ in juxtaposition with the ink-bag,
as in the recent Calamary; and subsequently many similar examples
have been found, both in England and on the Continent. Dr. Buckland
has given some exquisite figures of these fossils; and his collection
contains a matchless series of these most interesting organic remains.
In some specimens the ink-bag and its tube or duct, but little
compressed, are occasionally met with, having a brilliant nacreous
pellicle, the remains of the sheath, attached to the surface. The
ink-bag is sometimes of considerable magnitude; specimens have been
found at Lyme Regis nearly a foot in length.[407] The circumstance of
the ink-bags being generally full of sepia admits of the inference (as
Dr. Buckland with his wonted acumen remarks), that these individuals
died suddenly; for their living analogues reject the inky fluid
upon the least approach of danger. The perfect condition of the bag
proves also their instantaneous enclosure in the deposit, for the
distended membrane would otherwise have burst from decomposition,
and the contents would have escaped. The fossil marine reptiles, the
Ichthyosauri, &c., with which these fossils are associated, present
similar phenomena, as we shall hereafter have occasion to remark, and
strengthen the probability, that swarms of the inhabitants of the
Liassic ocean were suddenly destroyed, and imbedded, on the area now
occupied by their remains.
[406] Geoteuthis has hooks on its arms; hut, being a Calamary
(_Teuthid_), it would probably have unequal arms.--_Mr. Woodward._
[407] The large ink-bags figured by Dr. Buckland (Br. Tr. vol. i. pp.
372-379, pl. xliv′.) belonged to the great Geoteuthis Bollensis, of
Schuble.--_Mr. Woodward._
In the cream-coloured limestone, of Solenhofen, so rich in organic
remains of the highest interest (_Wond._ p. 578), the soft parts
of naked Cephalopoda have also been discovered. I have figured,
_Lign. 140_, a beautiful specimen obtained by the late Count Münster,
which exhibits an imprint of the body, the arms and tentacles being
represented by ten double rows of horny hooks, which precisely resemble
those of Belemnoteuthis. M. D’Orbigny supposes that the original animal
closely resembled a recent decapod called _Enoploteuthis leptura_.
[Illustration: Lign. 148. Fossil Shells related to the Argonaut.[408]
Fig. 1.--Bellerophon costatus. _Mt. Limestone._ _Yorkshire._
2.--Bellerophon bilobatus. _Sil. Syst._
[408] Some naturalists consider the Bellerophon to be allied to the
Carinaria (_Heteropod_).
]
Bellerophon.--It has been already stated, that the animals of one
genus of the existing dibranchiate Cephalopoda are protected by a
thin, flexible, symmetrical, keeled shell, convoluted on a vertical
plane, and having but one chamber--this is the _Argonaut_, or _Paper
Nautilus_, an inhabitant of the Mediterranean. This animal belongs
to the Octopoda, or those which have eight arms; and in one pair of
these processes the extremities expand into broad and thin membranes,
by which the delicate, elastic, calcareous envelopement, or shell,
is secreted. There membranes usually encompass the shell, and meet
and overlap each other along its keel; and by them chiefly the shell
is retained in its position. When these membranes are withdrawn, or
the animal dies, the shell, having no muscular connexion with the
soft parts, readily separates from the body. Hence the doubts so long
entertained as to the relation between the animal of the Argonaut and
its shell, but which are now set at rest; the observations on the
living animal by Madame Tower, and the anatomical demonstrations by
M. Sander Rang, having removed the obscurity in which the subject was
formerly involved.
In the Silurian, Devonian, and Carboniferous deposits there are
several species of a genus of shells, the animals of which are by
some considered to have been analogous to the recent Argonaut. It is
named Bellerophon. I have figured two species; one from the Mountain
Limestone, _Lign. 148, fig. 1_; the other from the Silurian System.
There are about thirty British species, most of which are of small
size; some of them are keeled, others have a slight dorsal depression,
as in _fig. 1_. and many have the back rounded, and the sides lobed, as
in _Lign. 148, fig. 2_ .
FOSSIL TETRABRANCHIATE CEPHALOPODA.
I am not aware of the existence of any British fossils analogous to
Spirula (_dibranchiate_); for the minute fossil polythalamia, formerly
referred to this class, are now known to have belonged to animals
possessing an organization altogether different, as we have already
explained (see p. 369). I therefore proceed to notice the fossil
remains of those _Cephalopoda_ which were furnished with an external
shell having its cavity divided by cells, which are perforated by a
hydraulic tube or siphuncle; and of which group the recent Nautilus is
the type.
[Illustration: Lign. 149. Nautilus pompilius in its shell.
_a._ The animal, occupying the last or body chamber of the shell.
_b._ The shell cut vertically through the middle, and showing the
air-chambers and the siphuncle.
]
The appearance and structure of the recent shell are familiar to
every one; a correct knowledge of the nature of the original animal
has, however, been obtained but very recently. In its general
characters the animal of the Nautilus, which is an inhabitant of the
seas of hot climates, resembles the naked Cephalopoda; it possesses
four _branchiæ_, or gills, and numerous hollow arms and retractile
tentacula. Its head is furnished with a muscular flattened disk, which
serves as an operculum to the shell when the animal is retracted. The
beaks are horny, and coated at their tips by calcareous matter. It has
no ink-bag, and is destitute of fins or other organs for swimming. The
body occupies the ample outer cell of the shell, to which it is firmly
attached by two lateral muscles; and it has a siphuncle, that passes
from the posterior part of the animal through the shelly tube, and by
which communication is maintained with the entire series of cells or
chambers. The siphuncle is provided with a small artery and vein, and
traverses the entire series of chambers, thus maintaining the vitality
of the shell. Mr. Edwards considers that "it may be looked upon as an
elongated cæcum, and that it is not under any circumstances used by the
animal as a hydrostatic balance."[409]
[409] The reader interested in this subject should consult the
_Memoirs_ by M. Valenciennes, Mem. de l’Inst.; M. Vander Hoven, in the
Proceedings of the Zoological Society; Prof. Owen’s _Memoir on the
Pearly Nautilus_, Mr. Gray’s paper in the An. Nat. Hist., Mr. Edward’s
Monograph in the Palæont. Soc., and Mr. Woodward’s _Manual_.
Upon making a vertical section of the shell, the inner volutions
are exposed, and the cavity is seen divided at regular intervals
into cells, by smooth, concave, nacreous septa; these vary in number
according to the age of the individual; there are about thirty-five
in an adult specimen. The partitions are pierced in the _centre_ by
a shelly tube, which traverses each cell to within a short distance
of the next partition; and this tube is rendered a continuous channel
in the living animal, by the membranous siphuncle. This series of
air-chambers constitutes an apparatus which renders the Nautilus nearly
of the same specific gravity as the surrounding water, and enables
it to rise to the surface of the sea, or sink to the bottom, by a
very small amount of muscular exertion. The Nautilus swims, like the
Cuttle-fish, by expelling the water from its respiratory chamber; the
walls of which are very thick and powerful muscles.
From this very general description of the only living representative
of the numerous genera of tetrabranchiate Cephalopoda, which swarmed
in such prodigious numbers in the ancient seas, we may pass to the
consideration of the fossil Nautili, and their related congeners. Our
remarks must be limited to the genera that will serve to demonstrate
the most important modifications of structure, and explain the nature
of the fossil remains of this extensive class of extinct beings.
The genera into which these shells are distributed are founded upon
the mode in which the shell is coiled, its form, the character of the
partitions or septa, and the situation of the siphuncle. A little
reflection will enable the student to understand the principles of
this classification. The essential character of all the shells of this
class, is to have an external chamber larger than the inner chambers,
and which contains the body of the animal; to be divided internally
into different compartments, by partitions (concavo-convex, with the
concavity outwards); and to have a pipe or tube extending from the
outer open chamber to the innermost cell. They are divided into three
groups or families.
1. The Nautilidæ (_Bd._ pl. xxxi.): in these the septa are smooth, or
but slightly undulated, and the siphuncle either traverses the centre
of the cell-partitions, or is situated towards the inner margin or turn
of the spire.
2. The Orthoceratidæ (_Lign. 155_): in these the siphuncle is
complicated in its structure; it is central or lateral; the septa are
smooth. (_Woodward’s Man. Moll._ p. 87.)
3. The Ammonitidæ (_Bd._ pl. xxxv-xlii.): in these the septa are
more or less waved, and their margins foliated or crenated, that is,
indented; and the siphuncle is situated at or near the outer margin.
In the Nautilus, the shell is convoluted on the same plane, in spiral
whorls, all of which are contiguous, and the siphuncle is central.
The British strata contain about sixty species of Nautili. The
Tertiary formations have yielded five or six; the Cretaceous a like
number; the Lias and Oolite ten or eleven; the Carboniferous about
thirty species; and the Devonian two species. In the London Clay a
large and beautiful species is abundant (_Nautilus imperialis._ _Min.
Conch._ tab. i.), having the shell very commonly entire; but the outer
opaque coat frequently flakes off, and exposes the pearly or nacreous
internal layer. The septa generally retain their original nacreous
structure, and the cells are either occupied by clay or marl, or are
partially filled or lined with calcareous spar, brilliant pyrites, or
other mineral matter. These Nautili are often found constituting the
nuclei of the _septaria_, or clay nodules, with which this deposit
abounds.[410] The small species, _N. centralis_ (_Ly._ _fig._ 179),
and _Nautilus_ (_Aturia_) _ziczac_ (_Wond._ p. 247), occur in the same
strata. The London Clay of the Isle of Sheppey and of the coasts of
Hants and Sussex is productive of these fossils.
[410] Three other well-marked species are figured and described by Mr.
Edwards (Monog. Pal. Soc.) from the English eocene strata: viz. _N.
Sowerbyi_, _N. urbanus_, and _N. regalis_.
[Illustration: Lign. 150. Fossil Nautili. _Chalk marl._
Fig. 1.--Beak of a Nautilus, (_Rhyncolite._) Back view.
1_a_.--Anterior view of the same.
1_b_.--Profile of the same.
2.--Vertical section of Nautilus pseudo-elegans. _Hamsey._
_a._ The siphuncle.
3.--Front view of N. Deslongchampsii. (_M. D’Orbigny._) _Hamsey._
3_a_.--Lateral view of the same.
]
In the White Chalk near Lewes, casts of several very large Nautili
have been found; but shells of this genus are more abundant in the
lower division, the _Chalk-marl_. A large and beautiful species,
_Nautilus elegans_ (_Min. Conch._ tab. 116), is not unusual in the
marl-pits near Lewes, Clayton, Steyning, &c. and may be considered as
characteristic of that portion of the Cretaceous deposits. The first
specimen discovered (_Foss. South D._ tab. xx) was from the marl-bank
immediately at the foot of the mound on which stands the church of
Hamsey, a little hamlet on the north of Lewes; a spot from which I
obtained numerous other cephalopodous shells, at that time unknown as
British species. The collocation of fossils at Hamsey is similar to
that observable in the quarries at St. Catherine’s Mount, near Rouen.
These remains only occur as casts, no vestige of the shell remaining;
but sections will sometimes show the situation of the siphon, its tube
being filled with a different material from that which occupies the
cells. This is exemplified in the section of a smaller species (_N.
pseudo-elegans_, _Lign. 150, fig. 2_), in which the channel of the
siphon is filled with a dark-coloured marl, _a_; the lines formed by
the section of the smooth septa are also shown. In the same lignograph,
_fig. 3_, a front view and profile of another chalk-marl Nautilite are
figured.[411]
[411] The student will find a section of the shell of the recent
Nautilus a very instructive object of comparison, in the investigation
of the fossils of this family.
[Illustration: Lign. 151. Nautilus elegans.
_Lower Chalk._ _Lewes._ (1/6 _nat. size_.)]
[Illustration: Lign. 152. Nautilus Saxbyi. _Lower Greensand._]
In the Chalk, as well as in many other calcareous deposits, the shells
of the Nautili, Ammonites, &c. are very rarely preserved; even the
internal septa are often dissolved, and the stony casts, moulded in the
cells, remain distinct, and readily separate (_Lign. 153_). An entire
series, from the innermost cell to the outer chamber, may sometimes be
obtained (in the Coralline Oolite); forming, as it were, a dissected
model of the internal structure.[412] The beaks or mandibles are
occasionally found fossil (_Lign. 150, fig. 1_).
[412] _Bd._ pl. xlii. _fig._ 1: see also plates xxxi. to xliii., for
illustrations of Nautilites.
[Illustration: Lign. 153. Casts of chambers of Nautilus and Ammonite.
(1/2 _nat._)
Fig. 1.--Cast in calcareous spar of a chamber of Nautilus.
_From the London Clay._
2.--Cast of a chamber of Ammonites excavatus.
_From the Coral Rag._
]
[Illustration: Lign. 154. Clymenia: 1/2 _nat._ _Devonian._
Fig. 1.--Clymenia Sedgwickii.
2.--Front view of the same.
3.--Vertical section of C. striata, showing the siphunculus on
the inner edge of each septum.
4.--Suture of C. striata.
]
Clymenia (_Lign. 154_, _Ly._ _fig._ 406).--This genus belongs to the
Nautilidæ, and is peculiar to the Devonian deposits. It differs from
the allied genera in the siphuncle being situated on the inner margin
of the septa. The shell is discoidal, and the septa are very slightly
lobed. At Elbersreuth, near Bareuth, in the N. E. of Bavaria, the
Devonian strata abound in these shells; thirty-five species have been
found, the greater number being peculiar to that locality.
In England they are chiefly found at South Petherwin, Cornwall, and in
the Devonshire marbles. (_See Phillip’s Pal. Foss. Devonshire._)
[Sidenote: ORTHOCERAS.]
Orthoceras (straight shell), _Lign. 155._--The shells of this genus
may be described as Nautili uncoiled and extended in a straight line.
They are straight, elongated, chambered shells, with smooth and gently
undulated septa, which are concave towards the opening or upper part,
and have the siphuncle either central, or not far removed from the
centre. The _Orthoceratites_ more especially belong to the ancient
Secondary strata. They first appear in the Silurian, and abound in
the Devonian and Carboniferous. They vary in size from a few inches
to several feet in length, and eight or nine inches in diameter; and
in form, from a slender elongated cone, to a short, massy, almost
spherical figure, with a contracted orifice. Some examples have been
noticed with upwards of sixty cells. Mr. Sowerby figures and describes
_O. giganteum_ (_Min. Conch._ tab. 246), from Scotland, as exceeding
seven or eight feet in length; and I discovered on the beach at
Brighton, where it had probably been brought by some vessel, among
ballast, a fine fragment of the same species, indicating as great
a magnitude. Several species are figured, _Lign. 155_, to show the
structure and appearance of these fossils. The casts of the separate
cells are often found. The section, _fig._ 3, from the red marble of
Devonshire, beautifully displays the situation of the siphuncle, and
the lines of the septa. The shelly siphuncle, which is moniliform
(_bead-like_), or dilated at each chamber, is replaced by white spar;
and the membranous internal tube is filled with a dark substance,
probably molluskite.
[Illustration: Lign. 155. Orthoceratites.
Fig. 1.--Orthoceras striatum. (_Min. Conch._) _Devonian._
2.--Orthoceras conicum. _Whitby._ _Carboniferous._
3.--Vertical section of an _Orthoceras_, showing the central
siphon, and the chambers. _Devonshire._
4.--Orthoceras laterale. _Carb._ (_Min. Conch._)
5.--Orthoceras gregarium. (_Munch. Sil. Syst._)
_a._ One of the septa.
_b._ A portion covered at the upper part by the shell.
_c._ The lower part of the same specimen, displaying the septa.
]
There are some species in which the internal tube, as well as the
external, is calcareous, and the two are connected at regular
intervals, by radiating, hollow processes. These Orthoceratites have
been principally obtained from the Silurian limestones, at Lake Huron;
they also occur in Ireland. Mr. Stokes, who first investigated their
structure, has arranged them in a distinct genus, with the name of
_Actinoceras_ (_radiated-horn_).[413]
[413] See Geol. Trans, second series, vol. v. p. 708.
Slabs of reddish Devonian limestone, containing Orthoceratites, may be
seen in some of the pavements at Hampton Court, and in Chelsea College,
which when wet present excellent sections of the enclosed shells.
[Illustration: Lign. 156. Ammonites from the Cretaceous Formation.
Fig. 1--Ammonites varians. _Chalk-marl._ _Hamsey._
2.--Ammonites Dufrenoyi.
2_a_.--Shows the keel and septum of the same.
3.--Ammonites lautus. _Galt._ _Folkstone._
3_a_.--Keel and septum of the same.
]
Ammonitidæ.--The Ammonites, or _Cornua Ammonis_ (so called from a
supposed resemblance to the horns engraven on the heads of Jupiter
Ammon), are among the most common and well-known fossils of the British
secondary strata. In some districts, as in Yorkshire and Somersetshire,
where the Ammonites abundantly prevail, they were noticed in very
remote times. Local legends, ascribing their origin to swarms of snakes
turned into stone by the prayers of some patron saint, are still
extant, and are perpetuated by the name of snake-stones, by which these
fossils are provincially known. The Lias, near Whitby, in Yorkshire,
contains immense numbers of two or three species, one of which (_Am.
bifrons_) is figured in _Lign. 127, fig. 7_, and another in _Lign.
157_.
[Illustration: Lign. 157. Ammonites communis.
_Lias._ _Whitby._]
The shells comprehended in this family are either spiral, involute,
arched, or straight; their septa are deeply lobed, and have the margins
foliated. The siphuncle is dorsal, as shown by the notch in the cast,
_Lign. 156, fig. 3a_. Several hundred species have been described;
they are divided into genera which are characterized by essential
modifications in the direction of the spire, and the inflections of the
septa. Thus, in the _Ammonites_, _Lign. 156_, the spire is involute,
and all the turns contiguous; in _Crioceras_ (_curved-horn_), _Lign.
160, fig. 2_, evolute; in _Scaphites_, incurved at both extremities,
_Lign. 162_; _Hamites_, bent like a siphon, or hook, _Lign. 161,
fig. 1_; _Turrilites_, spiral, round a vertical axis, _Lign. 163_;
and in _Baculites_, straight, _Lign. 161, fig. 2_. New genera are
continually being added, to embrace modifications of structure which
appear to be too important for specific distinctions. I will endeavour
to render this arrangement more clear to the student by the following
definitions.
A straight tube, or horn, of an elongated conical figure, tapering to
a point, and having its cavity divided by transverse partitions, which
septa are not straight, but undulated, and their edges, which fit into
the walls of the tube, deeply wrinkled, and the whole series pierced
by a pipe running along near the outer margin, would be the model of
the shell termed _Baculites_, _Lign. 161, fig. 2_, (_Bd._ pl. xliv.
_fig._ 5;) which may be regarded as a straight Ammonite. A similar
shell, gently arched or curved, would be a _Toxoceras_, _Lign. 160,
fig. 1_; the same tube, bent upon itself, like a siphon, into unequal
limbs, not contiguous, a _Hamites_, _Lign. 161_ (_Bd._ pl. xliv.
_fig._ 10); bent and approximate, or anchylosed in a straight line,
_Ptychoceras_, _Lign. 161, fig. 4_; partially convoluted, the whorls
contiguous, and the free end recurved, _Scaphites_, _Lign. 162_; the
same form, but the spire not contiguous, _Ancyloceras_, _Lign. 160,
fig. 3_; spirally twisted around an axis, _Turrilites_, _Lign. 163_
(_Bd._ pl. xliv. _fig._ 14); coiled, but the turns not touching each
other, _Crioceras_, _Lign. 160, fig. 2_; lastly, coiled up in the
form of a disk, all the turns being contiguous, _Ammonites_.
[Sidenote: AMMONITE.]
Ammonites. _Lign. 156, 157, 158._--Shell discoidal, more or less
compressed, whorls of the spire contiguous, and often visible; septa
lobed, their margins deeply sinuated; aperture symmetrical, border or
lip thickened, often notched and auriculated. Siphuncle dorsal.
The student will be able readily to distinguish Ammonites from Nautili
by attention to the above definition. The situation of the siphuncle,
the foliated or wrinkled edges of the septa, as shown in the cast,
_Lign. 156, fig. 2_; and when these characters are wanting, the
arched ribs and elevations, as in _figs._ 1 and 3, will serve as
discriminating features. Like the fossil Nautili, the Ammonites most
commonly occur as casts, the shell having been dissolved. Sometimes
these consist of semi-transparent calcareous spar, the cast of each
cell being distinct, but held together by the interlocking of the
foliations of the septa; such examples are of great beauty and interest
(see _Bd._ pl. xlii. figs. 2, 3); they most frequently occur in the
limestones of the Oolite. The siphuncle is often preserved, even in
the chalk specimens, in which all traces of the shell are lost. In a
large Ammonite from, near Lewes, not only the shelly siphuncle remains,
but even the internal membranous tube, converted into dark molluskite.
Separate portions of similar siphuncles occur in the chalk, and have
been mistaken for tubular shells.
[Illustration: Lign. 158. Ammonites Jason. 1/2 _nat._
_Oxford Clay, Trowbridge, Wilts._
_a._--Lateral processes of the margins of the aperture.]
The outer lip, or margin of the aperture, is occasionally found entire.
In some species there is a dorsal process, as in a very common Chalk
Ammonite (_A. varians_, _Lign. 156, fig. 1_), which extends far
beyond the margin; in other species, from the Oxford Clay, there are
long, narrow, lateral appendages, (_Lign. 158_). In the collection of
S. P. Pratt, Esq., there is a small Ammonite, from the Inferior Oolite
of Normandy, in which these processes meet over the aperture, leaving
only a circular aperture towards the back of the shell (where the
siphuncle of the animal would be situated) and a narrow fissure on the
side next the involute spire. The specimen is unique, and can scarcely
be regarded as a normal form.[414] (Mr. Woodward.)
[414] M. Steenstrup has described a species of _Purpura_, which at
the close of its life shuts up the aperture of its shell, with the
exception of the respiratory siphon.--_Mr. Woodward._
From the small size of the cells of the Ammonites, particularly in
those species which are of a depressed or flattened form, it was
long doubted whether the outer chamber could have been sufficiently
capacious to contain the body of the animal; and it was supposed that
these shells were internal, like the recent _Spirula_, or _Crosier_.
But Dr. Buckland has clearly demonstrated, that the outer cell of the
Ammonite, if restricted in breadth, is sufficiently ample in length to
have contained the soft parts of a Cephalopod, equal in magnitude to
the largest known specimens, its proportion to the chambered part being
as considerable as in the Nautilus. The outer chamber often occupies
more than half, and in some instances the entire circumference of the
outer whorl (see _Bd._ pl. xxxvi.).
In certain argillaceous deposits, as the Galt, and the clays of the
Lias, Ammonites with the shell preserved are abundant; generally
the outer opaque layer is wanting, or adheres to the matrix when a
specimen is removed, leaving only the internal nacreous, or pearly
coat. Folkstone, on the coast of Kent, is celebrated for examples of
this kind, which may easily be collected from the Galt, which forms
the base of the cliffs, at Eastware Bay. Watchett, in Somersetshire,
is equally rich in the pearly Ammonites of the Lias; entire layers of
these beautiful organic remains occur in the limestones and in the
shale exposed at low water.[415]
[415] A splendid group of these Ammonites may be seen in the Gallery of
Fossils at the British Museum.
The shell of the Ammonite is generally thinner and more delicate than
that of the Nautilus. However thin these shells may be, they are
possessed of great strength of structure. Not only is the shell one
continuous _arch_, but it is moreover provided with transverse arches
or corrugated _ribs_, which, like the flutings on metal pencil-cases,
and _corrugated sheet-iron_, greatly strengthen the thin material.
These ribs are further subdivided, so as to multiply supports as the
convexity of the shell enlarges, in a manner somewhat similar to the
_groin-work_ of vaulted roofs. The spines, tubercles, and bosses, which
often arise from the ribs, are so many additions to the strength of
the latter. The sides of the shell are also supported by the transverse
plates forming the _septa_, or divisions of the chambers, and, as
these plates are very sinuous where they meet the sides of the shell,
they distribute their support over a considerable portion of the
surface.[416] These complicated edges of the _septa_ form the delicate
and intricate lines of foliation (_sutures_) seen on the casts of
Ammonites (_Lign. 156, fig. 2_), Baculites (_Lign. 161, fig. 3_),
Hamites, &c. In some species the shell is thick and dense, as in the
Ammonites of the Kimmeridge Clay near Aylesbury, in which one species
(_Ammonites biplex_, _Min. Conch._ pl. ccxciii.) in particular abounds,
and is very generally invested with the shell, as perfect as if recent.
The same Ammonite occurs in the Portland limestone above, in the state
of casts, without any vestige of the shell. In some strata the shell is
replaced by calcareous spar; in others by silex or flint.[417] In the
pyritous clays and shales of the Lias, the shell and all its delicate
internal mechanism are coated with or replaced by brilliant sulphuret
of iron, forming the most exquisite natural electrotype imaginable.
Polished vertical sections of these fossils often exhibit the inner
cells filled with transparent white calcareous spar; sometimes with
groups of crystals of sulphate of lime. The Ammonites of the Galt,
and of the Kimmeridge Clay, are also frequently imbued with the same
mineral.
[416] See Bd. i. p. 339, &c.
[417] See an admirable figure of a chalcedonic specimen, exhibiting the
foliated septa of an Ammonite, _Bd._ pl. xli.
There are about two hundred identified species of Ammonite in the
British strata, ranging through all the secondary formations; they have
not been found in the Tertiary deposits. They vary in size from half an
inch to four feet in diameter.[418]
[418] I have seen imprints of the large Chalk Ammonite, _A. peramplus_
(Min. Conch. pl. ccclvii.), on the shore off Rottingdean, and Beachy
Head, which indicated even larger proportions.
Certain species are restricted to particular formations, and are
therefore oftentimes of essential aid in determining the relations of a
deposit; for example, the _Galt_ contains several species not found in
the upper division of the Chalk; and in the Chalk-maid are species that
have not been discovered in other strata. Certain Ammonites of the Lias
are peculiar to that formation (as _A. Walcottii_, _Lign. 127, fig.
7_, p. 397; and _A. communis_, _Lign. 157_). Ammonites of species allied
to those of our Middle and Lower Oolites have been discovered in strata
in the Himalaya mountains, several thousand feet above the level of the
sea.
[Illustration: Lign. 159. Goniatites. _nat._
_Carb. Syst._
Fig. 1.--Goniatites Listeri.
2.--Goniatites striatus.
3.--Outline of a suture of _Goniatite_.
4.--Outline of a suture of _Ammonites venustus_.
The _Arrows_ in figs. 3 and 4 denote the direction of the dorsal line.
]
[Sidenote: GONIATITES. CERATITES. CRIOCERAS.]
Goniatites, _Lign. 159._--From the numerous family of Ammonites, a
separation has been made of a large division, in which the margins
of the septa are not deeply notched or foliated, and are destitute of
lateral crenatures or denticulations, so that their outline always
presents a continued uninterrupted line. The siphuncle is relatively
small. The last or outer cell of the shell extends beyond one turn
of the chambered part. The back is occasionally keeled, but in most
species is round. In illustration of this genus, which is named
_Goniatites_, I have selected two common species (_Lign. 159_) from the
Carboniferous limestone, and annexed outlines of a suture (the edge of
the septum) of a Goniatite, and of an Ammonite, for comparison. The
importance of the separation of this type of Ammonites into a distinct
genus, relates to the Goniatites being restricted to some of the older
sedimentary strata; for although there are sixty British species, none
of them have been observed above the Carboniferous system.[419]
[419] _G. Henslowi_, _G. striatus_, and _G. sphæricus_, are figured in
_Bd._ pl. xl.
In Ceratites the sutures are more simple than in the Ammonite, being
lobed rather than foliated; and the alternate lobes have their edge
crenulated or finely toothed. (_C. nodosus_, _Bd._ pl. xl.) This genus
is found in the Muschelkalk and the Keuper formations of Europe and
Asia.
Our limits will not permit us to extend this notice of the very
numerous family of Ammonitidæ,[420] except to offer a few illustrations
of some of the modifications in form to which we have already alluded,
and which will assist the student in discriminating these fossil
remains.
[420] For further information, Dr. Buckland’s Treatise, and the
respective articles in the Penny Cyclopædia, may be referred to. Mr.
Woodward’s Manual should be consulted for the classification of the
family, and M. D’Orbigny’s Paléontologie Française for the illustration
of species.
Crioceras (_coiled-horn_), _Lign. 160, fig. 2._--This shell differs
from the Ammonites in the turns of the spire being distant from each
other. The siphuncle is continuous, and the septa are regularly divided
into six lobes. I have found specimens of this genus in the Chalk-marl
at Hamsey, and in the White Chalk, near Lewes (_Foss. South D._ tab.
xxiii. _fig._ 9).
[Illustration: Lign. 160. Shells of the family Ammonitidæ.
_Chalk and Greensand._]
Fig. 1.--Toxoceras Emericianum, and its septum. _Hamsey._
2.--Crioceras Puzosianum. (_M. D’Orbigny._) _Lewes._
3.--Ancyloceras furcatum, and its septum. _France._
In the genus Ancyloceras (_incurved horn_), _Lign. 160, fig. 3_, the
whorls are separate, and, at first, spiral (like _Crioceras_); but
afterwards the shell is prolonged, and then inflected at the large
extremity, like a Scaphite, but the whorls are not contiguous.
A very large species of _Ancyloceras_ occurs in the Kentish Rag, near
Maidstone, some specimens of which are eighteen inches in length. It
is figured and described, by the name of _Scaphites Hillsii_, in the
admirable Memoir of Dr. Fitton on the Strata below the Chalk (_Geol.
Trans._ vol. iv. pl. xv.); the present genus was not then established.
The Shanklin Sand in the Isle of Wight also contains a gigantic
species, which is figured and described by Mr. J. D. Sowerby, in the
_Geol. Trans._, as _Scaphites gigas_. _Ancyloceras_ occurs also in the
Oolite.
[Sidenote: TOXOCERAS. HAMITES.]
In Toxoceras (_bow-horn_), _Lign. 160, fig. 1_, the shell is slightly
curved, like a horn. Two or three species of _Toxoceras_ are found
at Hamsey. The tubercles, in the casts, are the bases of spines,
with which the back of the shell was armed, as I have ascertained
by examples examined in the rock (see _Foss. South D._ tab. xxiii.
_fig._ 1). The specimens figured of the above two genera occur in the
_Neocomian_ strata of France.
Hamites (_hook-shaped_). _Lign. 161, fig. 1._--Shell involute,
spiral, the turns not contiguous; spire irregular, elliptical; the
large end reflected towards the spire. The term _Hamite_, proposed by
the late Mr. Parkinson, was formerly given to all the fragments of
sub-cylindrical chambered shells, that were bent, or slightly hooked;
and the genera _Ancyloceras_, _Toxoceras_, &c., have been separated
from them, by M. D’Orbigny. But from fossils recently obtained from
Cretaceous strata in Pondicherry, and other parts of India, it seems
probable that these genera will be found to merge into each other; at
present it is convenient to keep up the distinction. The Hamites are
distinguished from Ancyloceras, which they most resemble, by their
elliptical, irregular spire.
Ptychoceras (_folded horn_). _Lign. 161, fig. 4._--This is another
genus formed from the Hamites. The shell is bent double in the shape
of a siphon, and the limbs are united together. The specimen figured is
from the _Neocomian_ strata of the Lower Alps.
[Illustration: Lign. 161. Hamites, etc. from the Chalk-marl.
Fig. 1.--Hamites cylindraceus, with part of the shell. (_M. D’Orbigny._)
2.--Baculites baculoides, with the mouth entire. _Hamsey._
3.--Part of the stem of the same species, showing the sinuous
septa. A detached septum is figured above.
4.--Ptychoceras Emericianum. (_M. D’Orbigny._)
]
[Sidenote: BACULITES.]
Baculites (_staff-like_). _Lign._ 161, figs._ 2 and 3.--This, as the
name implies, is a straight, elongated, conical, chambered shell; the
upper part is destitute of septa, and probably contained the body of
the animal.
In my early researches in the Chalk-marl of Hamsey, I discovered
numerous solid, oval, and cylindrical pipes of marl, with scarcely
any vestige of organic structure, whose origin it was impossible to
determine. At length I found the specimen, _Lign. 161, fig. 2_, which
showed the perfect aperture of a chambered shell; and afterwards I
found portions which displayed the foliated septa. (_Foss. South D._
tab. xxiii. _figs._ 5, 6, 7.) The Baculite, when perfect, is elongated
to a point; the septa are very numerous and foliated; the siphuncle
is situated on the margin. I have a splendid specimen from the Chalk
of France, (collected by _M. Alex. Brongniart_,) which is composed of
distinct casts of the cells, held together by the deep inflections of
their margins, in the same manner as are the sparry casts of Ammonites,
previously described.[421]
[421] See _Bd._ pl. xliv, _fig._ 5.
The Galt, near Folkstone, abounds in fossils of the above genera,
principally of _Hamites_; and the nacreous substance of the shells
is very often preserved. From the Chalk-marl near Dover, Southbourn,
Ringmer, and Southerham, near Lewes, and from Clayton, near
Hurstpierpoint, in Sussex, I have obtained examples of several species.
[Sidenote: SCAPHITES.]
Scaphites (_boat-like_). _Lign. 162._--This name was given by Mr.
Parkinson (_Org. Rem._ vol. iii. pl. x. See _Pict. Atlas_) to some
small chambered shells from the Chalk and Shanklin Sand, of a boat-like
form, with the inner whorls coiled up in a spire, and half hidden by
the outer chamber, which becomes contracted and recurved on itself,
is destitute of septa, and terminates in an oval or transverse mouth.
The siphuncle is dorsal. An _Ancyloceras_ closely coiled would be a
Scaphite. Hamsey marl-pit yielded to my early researches the first
Scaphites discovered in the British strata, together with Turrilites,
and other cephalopodous shells, previously unknown in England.[422] The
Scaphite is of an elliptical form, the spire and the mouth approaching
close to each other; the spire occupies about one-half of the shell.
Except the thick outer lip or margin of the aperture, which is almost
constantly found changed into pyrites, it is rarely that any vestige
of the shell remains. The same mineral constitutes casts of the spiral
part; and these, when separated from the other portion, might be taken
for Ammonites; see _fig._ 2. There are two varieties at Hamsey; one,
with the surface covered by fine transverse striæ, which arise singly
from the inner margins, and bifurcate on the dorsal part; _fig._ 1. The
other is also striated, but has a row of prominent ribs on the inner
half of the broad central portion of the shell; _fig._ 4. Scaphites
occur in the Upper Green Sand of Dorsetshire, and in the Chalk-marl
in several places in England; and at Rouen, in France; and a large
species, _S. Cuvieri_, has been found in New Jersey.
[422] Sow. Min. Conch, vol, i. p. 53.
[Illustration: Lign. 162. Scaphites. _Chalk-marl._ _Hamsey._]
Fig. 1 and 4.--Scaphites æqualis. (_Parkinson._)
2.--Cast in pyrites of the spiral part of a Scaphite.
2_a_.--Front view of the same specimen.
3.--Front view of Scaphites æqualis.
[Illustration: Lign. 163. Turrilites. _Chalk-marl._]
Fig. 1.--Turrilites catenatus. (_M. D’Orbigny._) _France._
_a._--One of the septa.
2.--Turrilites costatus. _Hamsey._
[Sidenote: TURRILITES.]
Turrilites. _Lign. 163._--Shell spiral, more or less conical, coiled
obliquely round an axis, and turriculated. Spire sinistral, whorls
contiguous, apparent, with a perforated umbilicus. Edges of septa
very sinuous. Siphuncle continuous, situated either on the external
convexity, or near the suture at the base of the wreath.
The discovery of three species of these elegant shells rewarded my
researches in the little marl-pit at Hamsey, already noticed, and
were the first examples of the genus found in England.[423] Like the
Ammonites, Scaphites, Hamites, &c. with which they are associated, the
Turrilites of our Chalk-marl seldom possess any traces of their shells.
The specimens are solid and tolerably sharp casts, with occasional
indications of the septa, and more rarely of the siphunculus. They
vary in size from two or three inches to two feet in length; and
are frequently more or less elliptical, from compression. The three
species which generally occur in the Sussex and Kentish chalk, are _T.
costatus_, _Lign. 163, fig. 2_; _T. tuberculatus_ (_Foss. South D._
pl. xxiv. _fig._ 7), characterised by its four rows of tubercles; and
_T. undulatus_ (_Foss. South D._ pl. xxiv. _fig._ 8), the wreaths of
which are ornamented with plain, slightly undulated, transverse ribs.
These are all reversed, or _sinistral_ shells; that is, the spire
is twisted to the left, the aperture being on the right hand of the
observer when the shell is placed on its apex, as in _fig._ 1. Several
other species of Turrilites occur in the Chalk of France,[424] one of
which, _T. catenatus_, is represented _Lign. 163, fig. 1_.
[423] Sow. Min. Conch, tab. xxxvi.
[424] See M. D’Orbigny’s Paléontologie Française.
Some of the Turrilites attain a considerable magnitude. The largest
found in England is a specimen of _T. tuberculatus_ (_Min. Conch._ tab.
lxxiv.), from Middleham, in the parish of Ringmer, near Lewes; when
perfect, it must have been full two feet in length: it consists of six
wreaths, the siphuncle, in the state of pyrites, appearing in three or
four; portions of the nacreous internal layer of the shell remain.[425]
In some specimens in my possession, the form of the aperture, and the
termination of the columella, are distinctly shown; as in the fine
example the last whorl of which is represented in _Lign. 164_.
[425] This specimen is now in the British Museum.
[Illustration: Lign. 164. Turrilites tuberculatus, (_Bosc._) _nat._
_Chalk-marl, Lewes._
Showing the form of the aperture, and the spinous tubercles. The
specimen is a cast in indurated chalk-marl; the last wreath only is
figured.]
Fig. 1.--Posterior view, exhibiting the expanded outer lip, and the
obtuse termination of the columella.
2.--Front view, showing the form of the aperture.
_a._--Two tubercles, bearing spines.
The Chalk-marl of Lewes, of the Sussex coast, and of the cliffs near
Dover, and the Upper Green Sand of Dorsetshire, have yielded the
principal British specimens of this genus. Several species occur in
the lower cretaceous strata, at St. Catherine’s Mount, near Rouen,
associated, as in England, with Scaphites, Hamites, and other allied
genera.[426]
[426] See Fossils of the South. Downs for figures of many species of
the Cephalopoda of the Sussex Chalk.
[Sidenote: APTYCHUS.]
Aptychus, Meyer. (Trigonellites, _Parkinson_.) _Lign. 165._--Associated
with the remains of Ammonites in several localities, are found
flattened triangular bodies, from less than an inch to an inch and a
half in diameter, the nature of which is still somewhat problematical.
A good figure is given by Mr. Parkinson of one species (_Org. Rem._
vol. iii. pl. xiii. figs. 9, 10, 12. See _Pict. Atlas_), with the name
_Trigonellites latus_. These bodies frequently occur in pairs and in
apposition, as in the specimen figured in _Lign. 165_. Their structure
is cellular; one surface is slightly concave and striated, and the
other covered with minute circular pores. Altogether their appearance
is that of bodies enclosed in vascular integuments. It is supposed that
they are the opercula of Ammonites. These fossils are commonly found
in the last or body chamber of Ammonites, in the Oxford Clay, near
Chippenham, the Coral Oolite of Malton, the Lias of Lyme Regis, and
the lithographic limestone of Solenhofen. M. Ewald states that they
may be found in the Chalk _Scaphites_ by making a longitudinal section
of the body chamber: but I have not succeeded in detecting them in the
examples from the chalk-marl which I have broken up for that purpose.
As these bodies (alluded to by authors as _Trigonellites_, _Aptychus_,
_Munsteria_, &c.) will probably come under the observation of the
collector, especially among the fossils of the Kimmeridge Clay, these
remarks are introduced to suggest diligent research, in the hope that
the origin of these fossils may at length be discovered.
[Illustration: Lign. 165. Aptychus sublævis. 1/2 _nat._
_Kimmeridge Clay, Hartwell, Bucks._]
Fig. 1.--The convex surface.
1_a_.--Magnified section of portion.
2.--The concave side.
* * * * *
[Sidenote: DISTRIBUTION OF FOSSIL CEPHALOPODA.]
Geological Distribution of Fossil Cephalopoda.--Even from this short
review of the principal types of the fossil Cephalopoda, the great
interest which attaches to the study of this class of organic
remains is strikingly demonstrated. Their geological distribution
is alike replete with phenomena of an important character. In the
Lower Palæozoic (Lower and Upper Silurian) strata, the chambered
mollusks belong (with a very few doubtful exceptions) to the
Nautilidæ, namely, Nautilus, Lituites, Cyrtoceras, Orthoceras, &c.
The Devonian and Carboniferous systems contain Nautilus, Clymenia,
Gyroceras, Cyrtoceras, and Orthoceras, together with a peculiar group
of Ammonitidæ, the _Goniatites_. The Trias in general is extremely
poor in Cephalopoda; the Permian group affording but two species of
Nautilus, and the Muschelkalk two other species: but, in addition to
these, the Muschelkalk contains Ceratites, which is a genus peculiar
to the Triassic group, and chiefly abounds in the St. Cassian beds (in
the Austrian Alps), where it is accompanied by Nautilus, Orthoceras,
Ammonites, and Goniatites. In the Lias and Oolite Nautili abound,
and we meet for the first time with Belemnites. The same families,
viz. Nautilidæ, Ammonitidæ, and Belemnitidæ, prevail throughout the
Cretaceous strata. The Tertiary formations contain a few Nautilidæ
only; no vestiges of the Ammonitidæ and true Belemnitidæ, which, as
we have seen, swarmed in the ancient seas, are perceptible, while
in the existing oceans, the _Nautilus_ and _Spirula_ are the sole
representatives of the numerous shell-bearing cephalopoda of the
ancient geological eras. Thus, the Nautilidæ extend from the oldest to
the newest fossiliferous strata, the genus being still in existence:
the Ammonitidæ, on the other hand, though less ancient in origin, do
not pass beyond the limits of the cretaceous epoch.
In the following tabular arrangement these facts are placed in a more
distinct point of view:--
_Tabular View of the Distribution of Cephalopoda
through the Geological Epochs._
_Existing Genera_
{ Argonauta. } Octopoda. }
{ Octopus, &c. } }
{ }
{ Loligo, Cranchia. }(_Teuthidæ_).} }
{ Sepiola, Onychoteuthis, &c. } } } Dibranchiata.
{ }Decapoda. }
{ Sepia (_Sepiadæ_). } }
{ } }
{ Spirula. } }
{
{ Nautilus (_Nautilidæ_). Tetrabranchiata.
_General fossil in the Tertiary Formations_
{ Sepiadæ { Sepia, Spirulirostra, Beloptera, Belemnosis.
{
{ Nautilidæ { Nautilus and Aturia
_Cretaceous Deposits_
{ Belemnitidæ { Belemnites, Belemnitella, and Conoteuthis.
{
{ Nautilidæ { Nautilus.
{
{ Ammonitidæ { Ammonites, Crioceras, Scaphites, Ancyloceras,
{ Toxoceras, Hamites. Ptychoceras, Helicoceras,
{ Turrilites, Baculites.
_Oolite and Lias_
{ Sepiadæ { Sepia.
{
{ Teuthidæ { Teudopsis, Beloteuthis, Geoteuthis, Leptoteuthis,
{ { Ommastrephes.
{
{ Belemnitidæ { Belemnites. Acanthoteuthis, and Belemnoteuthis.
{
{ Nautilidæ { Nautilus.
{
{ Ammonitidæ { Ammonites, Ancyloceras.
_Trias_
{ Nautilidæ { Nautilus.
{
{ Ammonitidæ[427] {Ammonites, Goniatites, and Ceratites.
_Carboniferous System_
{ Nautilidæ { Nautilus, Gyroceras, Cyrtoceras, Gomphoceras, and
{ { Orthoceras, Actinoceras, &c.
{
{ Ammonitidæ { Goniatites.
_Devonian System_
{ Nautilidæ { Nautilus, Clymenia, Cyrtoceras, Phragmoceras,
{ { Gomphoceras, Orthoceras, Actinoceras, &c.
{
{ Ammonitidæ { Goniatites.
_Upper and Lower Silurian Systems_
{ Nautilidæ { Nautilus, Lituites, Gyroceras, Cyrtoceras,
{ { Phragmoceras, Gomphoceras, Oncoceras, Ascoceras,
{ { Orthoceras, Actinoceras, &c.
X/
[427] The Ammonitidæ are from the St. Cassian beds only.
With regard to the zoological affinities between the living and extinct
species of testaceous Cephalopoda, Dr. Buckland remarks, "that they
are all connected by one plan of organization; each forming a link in
the common chain which unites the existing species with those that
prevailed among the earliest conditions of life upon our globe; and all
attesting the identity of the design that has effected so many similar
ends, through such a variety of instruments, the principle of whose
construction is, in every species, fundamentally the same.
"Throughout the various living and extinct genera of these beings,
the use of the air-chambers and siphuncle of their shells, to adjust
the specific gravity of the animals in rising and sinking, appears to
have been identical. The addition of a new transverse plate within the
coiled shell added a new air-chamber, larger than the preceding one, to
counterbalance the increase of weight that attended the growth of the
shell and body of these animals." (_Bd._ p. 380.)
The occurrence of the Nautilus, and its congeners, among the earliest
traces of the animal kingdom, and their continuance throughout the
immense periods during which the family of Ammonitidæ was created,
flourished, and became extinct, and the existence of species of the
same genus at the present time, are facts too remarkable to have
escaped the notice even of those who are not professed cultivators of
geological science; and I am induced to quote the following beautiful
lines, by Mrs. Howitt, to impress this interesting phenomenon more
strongly on the mind of the youthful reader.[428]
[428] The poetess has, however, not been literally accurate regarding
the Nautilus and its habits, nor as to the formation of stratified
rocks, but has given a romantic rather than a scientifically correct
view of this interesting Cephalopod, and of the disappearance of its
congener. The young reader must, therefore, remember that the Nautilus
sometimes _floats_, but _never sails_; and that the whole race of
Ammonites _died out_ in course of time, and were not annihilated by
convulsive movements of earth and sea.
"TO THE NAUTILUS.
"Thou didst laugh at sun and breeze,
In the new created seas;
Thou wast with the reptile broods
In the old sea solitudes,
Sailing in the new-made light,
With the curl’d-up Ammonite.
Thou surviv’dst the awful shock,
Which turn’d the ocean bed to rock,
And changed its myriad living swarms,
To the marble’s veined forms.
"Thou wast there, thy little boat,
Airy voyager! kept afloat,
O’er the waters wild and dismal,
O’er the yawning gulfs abysmal;
Amid wreck and overturning,
Rock-imbedding, heaving, burning,
Mid the tumult and the stir;
Thou, most ancient mariner,
In that pearly boat of thine,
Sail’dst upon the troubled brine."
* * * * *
[Sidenote: ON COLLECTING FOSSIL CEPHALOPODA.]
On the Collection of British Fossil Cephalopoda.--In the Tertiary
formations of England, the remains of but seven species of Nautilus
(comprising Aturia) have been noticed; the large species (_N.
imperialis_) is the most common. These are generally in a good state of
preservation, and only require the careful removal of the surrounding
clay or marl. When pyrites largely enters into the composition of the
specimens, the investing matrix can seldom be effectually cleared off:
if the outer surface, and general form, be not well displayed, breaking
the specimen will often expose the inner cells, with the siphunculus,
in a beautiful state. The _Nautilus imperialis_ is occasionally
imbedded in the septaria of the Isle of Sheppey, and of Bognor and
Bracklesham, on the Sussex coast. Sections of such examples, in the
vertical direction of the enclosed shell, afford, when polished, very
brilliant and interesting fossils; the septa and the shelly tube of the
siphunculus are often preserved.
The Cephalopods of the Cretaceous formation, with the exception of
those in the argillaceous strata of the Galt, are generally destitute
of their shells, and only occur in the state of casts; and the
Chalk Nautili are liable to separate at the divisions of the septa,
and an entire series of the casts of the chambers may sometimes be
obtained, so as to display the entire form of the original shell. The
Ammonites of the White Chalk, although mere casts, yet retain their
configuration, the foliated margins of the septa dove-tailing them
together. I have already mentioned that search should be made along the
back of these specimens for the siphuncle, the shelly tube of which
is sometimes well defined. In the Chalk-marl the casts are sharper
than in the White Chalk, and generally of a deep ochreous colour,
with the lines of the sinuous septa clearly defined. The siphuncle
is occasionally preserved in pyrites, in the Ammonites, Nautili,
Turrilites, and Scaphites; and the outer lip or margin of the mouth, or
aperture, of the latter, and of the Ammonites, is frequently replaced
by the same mineral.
The Ammonites, Hamites, &c. of the Galt have their pearly coat
remaining, but this investment is extremely delicate; and although when
first removed from the marl it is beautifully iridescent, the vivid
hues are very evanescent, and the shell becomes opaque and of a light
fawn colour. Very commonly the shell flakes off, wholly or in part,
leaving a cast of indurated pyritous marl. I have preserved specimens
with the shell many years, by applying a thin coat of mastic varnish
with a soft camel-hair pencil, before the marl had become dry, and
while the shells were entire. The Galt Ammonites, like the Nautili of
the London Clay, are often invested with pyrites, and have the inner
cells and siphuncle well preserved.
The argillaceous strata of the Oolite and Lias contain Ammonites, &c.
in much the same state of mineralization as those of the Galt. The
Kimmeridge Clay, in some localities, particularly around Aylesbury (and
especially at Hartwell Park, the seat of Dr. Lee), abounds in Ammonites
with the shell as perfect and beautiful as if just dredged up from
the sea. But, like the fossils of the Galt, few of the specimens are
durable; although in many examples the shell may be preserved by the
application of mastic varnish. The most common Ammonite at Hartwell
is _A. biplex_ (_Sow. Min. Conch._), which varies from three inches
to one foot in diameter; the surface is covered by very strong ribs
that encircle the whorls. The shell is thick, and composed of several
laminæ.[429]
[429] According to the observations of my son, the outer layers,
when highly magnified, present an appearance of opaque areolæ, with
irregular radiating fibres; the inner laminæ are covered with minute
pores, apparently the orifices of tubuli, some of which are arranged
singly in crescents, and others are confluent, like short strands
of beads. I mention the fact to direct attention to the microscopic
examination of the structure of these splendid fossils.
The sparry casts of the separate cells of Ammonites which occur in some
of the calcareous beds of the Oolite, will not fail to be observed by
the collector. It is convenient to preserve such specimens either on a
tray or board, in which a groove is made for their reception, or in a
mould of gutta percha.
In collecting _Belemnitidæ_, the caution already given, of examining
the surrounding clay or marl, must not be disregarded; the student
should remember, that traces of the soft parts of the animals, even
of mere impressions of the body and head, with the tentacula and
their acetabula, or little horny rings and hooks, are more important
than the most splendid examples of the spathose durable osselet. The
guards should be selected with especial reference to their containing
the phragmocone (see _Lign. 141, fig. 2_), or chambered conical
shell, in the alveolus or cavity of the upper and larger end. An
apparently worthless fragment of a Belemnite will often be found to
possess this part of the structure, as in the example figured, which,
until fractured longitudinally, had been thrown by among useless
duplicates. The search for the remains of the fossil naked Cephalopoda,
as the Teuthidæ and Sepiadæ, and their ink-bags, must be made in a
like cautious manner. In the Lias marls, the ink-bag and its duct is
often found partially covered by a pellicle of nacre, without any
trace of the other parts of the animal. A reference to Dr. Buckland’s
plates (_Bd._ pl. xxviii. xxix) will familiarize the student with the
appearance of these fossil remains.
* * * * *
[Sidenote: LOCALITIES OF FOSSIL CEPHALOPODA.]
A FEW BRITISH LOCALITIES OF FOSSIL CEPHALOPODA.
Abingdon, Berks. Ammonites, fine casts in spar and limestone; Middle
Oolite.
Aylesbury, Bucks. Ammonites, several species; splendid examples of
_A. biplex_, with the shell remaining, in the Kimmeridge Clay.
Aymestry. Upper Silurian; Gomphoceras, Orthoceras, &c.
Bath. Fine Ammonites in the Oolite.
Beachy Head. Along the shore, gigantic Ammonites in the Chalk, at
low-water.
Benson, Oxfordshire. Fine Hamites, in Chalk-marl.
Blackdown, Devonshire. Beautiful siliceous casts of Ammonites; Green
Sand.
Bognor, Sussex. Nautili, in the Tertiary Clays and sandy Limestones;
also, along the neighbouring coast, in Septaria.
Bolland, Yorkshire. Mountain Limestone; Goniatites.
Boreham, near Warminster, Wilts. Nautili and Ammonites in Green Sand.
Bracklesham Bay, Sussex. Nautili in Tertiary Clay.
Bridport, Dorset. Ammonites; Inferior Oolite.
Brighton. In the Chalk, Ammonites, Belemnitellæ, &c.
Brill, Lucks. Ammonites, as at Aylesbury.
Buxton, Derbyshire. Goniatites; Mountain Limestone.
Charmouth, Dorsetshire. Ammonites, Belemnites, &c.; Lias.
Cheltenham. Ammonites, Belemnites, Nautili, &c. in abundance;
Inferior Oolite and Lias.
Chicksgrove, Tisbury, Wilts. Ammonites, several species; some
chalcedonic; Upper Oolite.
Christian Malford, near Chippenham. In Oxford Clay, Belemnites,
Belemnoteuthis, and Geoteuthis; _very fine_.
Clayton, near Hurstpierpoint, Sussex. In Chalk-marl, Ammonites,
Nautili, and Turrilites; very fine specimens.
Closeburn, Dumfriesshire. Orthocerata, large species; Silurian.
Comb Down, near Bath. Ammonites and Nautili; Oolite.
Connaught, Ireland. Goniatites; Mountain Limestone.
Cork. Orthocerata; Mountain Limestone.
Crockerton, near Warminster. Ammonites, in Galt.
Dover. In the cliffs, and along the shore, in Chalk and Chalk-marl,
Turrilites, Ammonites, Nautili, &c.
Dowlands, near Lyme. Fine Ammonites, &c. in the Lias.
Dundry, near Bristol. Ammonites, &c. Inferior Oolite.
Earlstoke, Wilts. Hamites, Ammonites, &c. in Green Sand.
Faringdon, Berks. In the gravel-pits, Nautili, Ammonites, &c. In the
Coral Rag, beautiful casts in limestone and spar of Ammonites,
Belemnites, &c.
Folkstone, Kent. In the Galt, at Eastware Bay, in the cliff, and
along the shore at low-water, Belemnites, Hamites, Ammonites, &c.
in profusion.
Hamsey, near Lewes, Sussex. Chalk-marl; Turrilites, Scaphites,
Hamites, Baculites, Crioceratites, Ammonites, Nautili; Belemnites,
very rare.
Hartwell, Bucks, seat of Dr. Lee. Splendid Ammonites, with their
shells, in Kimmeridge Clay.
Heytesbury, Wilts. Nautilus elegans, and other Chalk-marl Cephalopoda.
Horncastle. Very fine Ammonites.
Hythe, Kent. In Green Sand, large Ancyloceratites, Ammonites, &c.
Ilminster, Somerset. Upper Lias, Ammonites; Marlstone, Belemnites and
Ammonites.
Kelloway. Many beautiful Ammonites, &c.; Middle Oolite.
Keynsham, near Bristol. Splendid Nautili and Ammonites; the large _A.
giganteus_, two or three feet in diameter; and specimens with the
chamber filled with spar, of surpassing beauty; Lias.
Lewes, Sussex. Nautili, Ammonites, &c. in the Chalk and Marl quarries
of the vicinity.
London. Tertiary strata in the vicinity. Highgate Hill, fine Nautili,
and Aturia ziczac, Beloptera, &c.
Ludlow. Upper Silurian; Lituites, Orthoceras, Phragmoceras, &c.
Lyme Regis, Dorsetshire. Ammonites, Nautili, Belemnites, Sepiæ, &c.
in profusion in the Lias; and Scaphites and Turrilites in the Chalk.
Lympne, Kent. Ammonites, Ancyloceratites, &c. in Green Sand.
Maidstone, Kent. Ammonites, of large size, in Shanklin Sand.
Malton. Ammonites, several large species. Lower Oolite.
Marsham, near Abingdon. Ammonites; Oolite.
Marston Magna, near Ilchester. _Ammonite-marble_; Lias.
Newton Bushel, Devonshire. Nautilus, Orthoceras, Cyrtoceras,
Goniatites, &c. in the Devonian rocks.
Norwich. In Chalk, Belemnites in profusion; Ammonites, &c.
Nutfield, Surrey. Fuller’s-earth pits: beautiful Nautili (_N.
undulatus_, and _A. Nutfieldiensis_), and Ammonites.
Offham, near Lewes. In the Chalk-pits, large Ammonites; Chalk-marl
in a pit, on the right-hand side of the road, a quarter of a mile
north of the village, Hamites, Turrilites, Scaphites, Nautili, rare
species of Ammonites, &c.
Oxford. Quarries in the vicinity, Ammonites, Belemnites, &c.
Petherwin, Cornwall. Clymenia, Goniatites, Orthoceras, &c. in the
Upper Devonian rocks.
Portland. Upper Oolite; gigantic Ammonites.
Roak, near Benson, Oxfordshire. In Chalk-marl, Hamites, Ammonites, &c.
Scarborough. Kelloway Rock; Ammonites, &c.
Scarlet, Isle of Man. Nautili, &c.; Mountain Limestone.
Settle, Yorkshire. Goniatites; Mountain Limestone.
Sherbourn, Somersetshire. _Ammonite-marble_; Lias.
Southerham, near Lewes. In the Chalk-pits, large Ammonites; in the
Marl, Nautili, Ammonites, Turrilites, &c.
South Petherton, Somerset. Marlstone; Belemnites and Ammonites in
profusion.
Speeton, Yorkshire. Galt; Crioceras, Ancyloceras, &c.
Steyning, Sussex. In Chalk-marl near the town, Belemnites (_B.
lanceolatus_), Nautili, Ammonites, &c.
Swindon, Wilts. In the Portland-stone quarries, Ammonites, in
abundance; principally casts of _A. biplex_, and _A. triplicate_.
In the Kimmeridge Clay in the vicinity, Ammonites with the shell
preserved.
Tisbury, Wilts. In Portland-stone, fine Ammonites, often chalcedonic
(see _Bd._ pl. xli.).
Trowbridge, Wilts. In Oxford Clay, Ammonites, Belemnites, &c. were
obtained in great numbers during the railway cuttings.
Watchett, Somersetshire. Ink-bags of Sepiadæ, &c.; splendid
Ammonites; Lias.
Whitby, Yorkshire. Ammonites, Belemnites, &c. in abundance; Nautili,
&c.; Lias.
Yeovil, Somersetshire. Nautili and Ammonites; Inferior Oolite.
CHAPTER XIII.
FOSSIL ARTICULATA; COMPRISING THE ANNELIDES, CIRRIPEDES, CRUSTACEANS,
AND INSECTS.
The division of the Animal Kingdom termed _Articulata_, embraces, as
the name implies, those animals which have a _jointed_ body, generally
possessing an external-jointed skeleton, composed of segments more or
less annular and distinct. It comprehends six classes; namely--
1. Annelata, or Annelida; _i. e._ formed of rings; comprising the
Red-blooded Worms.
2. Myriapoda; as the Centipede.
3. Cirripedia; _i. e._ having curled-feet; as the _Balanus_ and _Lepas_
(Barnacle).
4. Crustacea; as the Crab, Lobster, and Water Flea.
5. Arachnida; Mites, Scorpions, and Spiders.
6. Insecta, or Insects.
Of the first, third, fourth, and sixth of these classes, remains occur
in the British strata, some being referable to existing, but the
greater part to extinct species and genera. I propose to describe a few
illustrative examples of the fossils belonging to each Class.
Annelida.--This name is given to a class of _Articulata_, consisting of
worms, whose bodies are formed of little rings, or annular segments,
and which have red blood; as the Leech, Earth-worm, &c. Some are
naked (the _Dorsibranchiata_ and _Abranchiata_), and move with great
celerity; as the _Gordius_, or Hair-worm, and the _Nereis_, so frequent
on the sands of the sea-shore. Others have shelly coverings (the
_Tubicolæ_), as the _Serpula_, and are sedentary, or fixed to other
bodies. The soft bodies of certain species are protected by a coat, or
tube, formed by the agglutination of sand, or other foreign substances,
as in the _Sabella_ (_Lign. 123, fig. 6_, p. 385).
The fossil remains of the testaceous Annelides are very abundant in
some deposits; and even the naked, flexible, soft-bodied forms have
left proofs of their existence in some of the most ancient sedimentary
rocks. Traces of nine species, belonging to five genera of these soft,
naked Annelides, have been observed in the Silurian strata of Britain.
[Illustration: Lign. 166. Fossil impression of Nereis. _Silurian
strata._
(_Drawn by Miss Murray._)
Nereites Cambrensis. (_Murch. Sil. Syst._) _Llampeter._]
[Sidenote: FOSSIL NEREIS. SERPULA. CIRRIPEDIA.]
The first notice of these remarkable remains appeared in the invaluable
work of Sir R. I. Murchison on the Silurian System.[430] The living
species of Nereis (_Dorsibranchiate_) are free, agile animals, having
a distinct head, provided with either eyes or antennæ, or both; they
are the most perfect in structure of all the Annelides. The fossil
represented in _Lign. 166_ indicates that the body of the original
was composed of about one hundred and twenty segments; the feet were
half the length of a segment of the body; and the _cirri_ of the feet
were longer than such segment. A more slender species, (_Nereites
Sedgwickii_,) the body consisting of a greater number of segments, is
also figured and described by Sir It. I. Murchison. Other impressions
in the same stone resemble those that would be produced by smooth
Annelides (_Abranchiate_) related to the _Gordius_, or Hair-worm.[431]
[430] Murch. Sil. Syst. p. 699.
[431] Murch. Sil. Syst. p. 701, pl. xxvii.; and M’Coy, Cambridge Pal.
Foss. p. 128, pl. 1. D.
Serpula.--The animals of this genus are sedentary or fixed, having
calcareous tubes or shells, but to which they have no muscular
attachment. They have plumose or arborescent gills affixed to the
anterior part of the body. The shelly tubes of the _Serpulæ_ are
constantly seen on our coasts, encrusting stones, rocks, shells,
sea-weeds, &c., and may be known by their contorted or twisted forms.
There are a hundred and fifty British fossil Tubicolæ. A large species
has been discovered in the Silurian rocks (_Murch. Sil. Syst._ pl. v.
_fig._ 1); several occur in the Carboniferous, Oolitic, and Cretaceous,
and many in the Tertiary strata. In the Upper Chalk, a smooth tortuous
_Serpula_ is not uncommon (_S. plexus_, _Min. Conch_, tab. 598);
it occurs in masses several inches long. But I have not observed
either in the Chalk, or in any other deposit, indications of banks of
_Serpulidæ_, like those now in progress off the Bermudas, and which
resemble coral-reefs in their solidity and extent.
Cirripedia.--These animals have a soft body, enveloped in a membrane,
which in some genera is protected only by a horny sheath, but in
general is enclosed in a shell composed of various calcareous
plates.[432] They have six pairs of feet, terminating in long,
slender, articulated tentacula, furnished with cilia, and coiled up
like tendrils at the extremities near the mouth. The name of the class
(_curled-feet_) has originated from the appearance presented by the
curled tentacula when projecting from the oval aperture of the shell.
The testaceous Cirripedes or _Barnacles_ are divided into two groups;
namely, the _sessile_, or those which in their adult state are fixed by
the base to other bodies, (Balanidæ,) as the Acorn-shell, or _Balanus_;
and the _pedunculated_, which have a process of attachment, peduncle
or stem, (Lepadidæ,) as the Duck-barnacle, or _Lepas_. But the young
animals of these genera have powerful locomotive organs, and are
capable of swimming, by sudden jerks, like some of the crustaceans,
to which class, especially in this stage of their existence, they
closely approach. But after a short period of freedom, the young
Cirripede fixes itself in some locality suitable to its economy, and
rapidly undergoes the transformation which results in the sessile adult
Barnacle or Lepas.[433]
[432] Until within the last few years the valves of the _Cirripedes_
have been generally figured and described in works on Conchology as
being allied to the _Mollusca_.
[433] See Mr. C. Darwin’s admirable Monograph on the Cirripedia,
published by the Ray Society, 1851.
Balanus. _Lign. 167, fig. 1.3_--The shell of this sessile Cirripede
is of a conical shape and cellular structure. It consists of a thick
plate at the base, or place of attachment; of a series of plates,
united by sutures, arranged around the body of the animal, and called
_parietal_ valves; and of pieces termed _opercular_ valves, by which
the aperture is closed. The shell of the _Balanus_, so common on the
rocks of our shores, and on every pile and pier within reach of the
tide, is composed of six parietal, and four opercular valves. The
fossil _Balanus_, _Lign. 167. fig. 1_, is from the Crag, a formation
containing many shells of this genus: in this example, the six parietal
plates of the conical shell only remain, but in some specimens the
opercular valves are also preserved. There are about twelve species
of Balanus in the Crag; but none have been found either in the older
Tertiary, or in the secondary rocks of England. In the newer _Pliocene_
deposits of the Sub-Apennines, and of North America, several species
are common.
[Illustration: Lign. 167. Fossil Barnacles and Pholades.
Fig. 1.--Balanus tesselatus. (_Sow. Min. Conch._) _Crag._ _Suffolk._
2.--Loricula pulchella. (_Mr. G. B. Sowerby, jun._) _Chalk._ _Kent._
_a._ The situation of the aperture of the shell.
3.--A valve (_Tergum_) of Scalpellum maximum. _Chalk._ _Lewes._
4.--Another valve (_Carina_) of the same species.
5.--Pholas priscus[434]; in wood. _Lower Green Sand._ _Sandgate._
_a._ One of the shells seen in profile.
6.--Univalve Shells (_Neritæ_) in hollows formed by _Pholades_.
(_Mr. Bensted._) _Lower Green Sand._ _Maidstone._
_a._ The _Nerites_ lodged in the cavities.
_b._ Fragment of wood remaining attached.
]
[434] Figs. 5 and 6 are referred to and described at pages 409 and 410,
vol. i.
Lepadidæ.--The pedunculated Cirripedes, of which the common
_Duck-barnacle_ is a well-known example, have a strong, muscular,
hollow stalk, or peduncle, which supports a multivalve shell,
containing the body of the animal. In _Pollicipes_ and _Scalpellum_
there are small calcareous plates covering the junction of the body
with the peduncle. Detached valves of several species of these two
genera are met with in the Chalk, Galt, and Shanklin Sand, of Kent
and Sussex; and three species have been found in the English Tertiary
beds.[435] The valves of these fossil Cirripedes are most usually
found in a disconnected state (_Lign._ 167, _figs._ 3 and 4); but
the Tertiary _Scalpellum quadratum_ is sometimes better preserved;
and Mr. Morris has described a most beautiful group of _Pollicipes_
(_P. concinnus_), attached to an Ammonite, from the Oxford Clay. Mr
Wetherell, of Highgate, has also discovered, in the Upper Chalk, near
Rochester, an almost perfect Cirripede, named by Mr. G. B. Sowerby,
jun., _Loricula pulchella_ (_Lign. 167, fig. 2_), and lately more
fully described in detail by Mr. Darwin.[436]
[435] See Mr. Darwin’s Monograph of the Fossil _Lepadidæ_,
Palæontographical Society, 1851.
[436] Monograph of the Fossil Lepadidæ, p. 81, pl. v.
Crustacea.--The animals whose fossil remains we have now to consider,
are characterised by their crustaceous external integument or shell,
which is disposed in segments, more or less distinct, the annular
portions supporting articulated limbs or appendages. They are aquatic,
free, locomotive beings, and possess distinct _branchiæ_, or organs
fitted for aquatic respiration. The Crab and Lobster are examples of
those tribes in which the external crust is calcareous, and "coloured
by a pigmental substance, diffused more or less irregularly through
it; and is formed upon and by a vascular organized integument, or
corium, which is lined by the smooth serous membrane of the visceral
cavities." (_Owen._) The subdivisions of this class have relation
to the forms, combinations, and proportions of the primary rings or
segments of the external crust or integument, but it will not be
requisite for our present purpose to enter upon this department of the
subject. It may, however, be necessary to mention, that in the normal
type of Crustaceans, the integument consists of twenty-one rings or
segments, which form the three regions into which the body is divided;
namely, the head or _cephalic_, the _thoracic_, and the _abdominal_;
each of which is assumed to consist of seven rings, although some of
these are generally anchylosed, and form but one segment; and even
the three regions are occasionally more or less blended together.
The cephalic portion of the crust contains the principal organs of
sense, and the commencement of the digestive apparatus, and includes
the masticatory appendages. The _thoracic_ portion is formed of the
rings to which the extremities serving for locomotion are attached:
and, together with the cephalic, contains almost all the viscera. The
consolidation of the rings or segments takes place most generally in
the cephalic, and next in frequency in the thoracic; and but rarely
occurs in the abdominal region. These animals possess organs of sight
variously modified, and in some species highly complicated; some have
smooth or simple eyes (_stemmata_), and others compound eyes, like
those of insects, with distinct facets. In one grand division (called
_Edriopthalmia_), the eyes are sessile and immovable; in the other
(_Podopthalmia_), they are supported upon moveable stems or peduncles.
These few remarks on the organization of the recent crustaceans are
required, to make our description of the fossil remains intelligible
to the general reader. As the shell, or calcareous integument, even
in those species in which it is very dense and thick, is moulded
upon the soft parts it envelopes, the experienced naturalist is able,
from its configuration alone, to obtain certain conclusions as to
the form, size, and position of the contained viscera; and, as these
animals annually shed their solid case and acquire a new one, which
is moulded on the soft parts, the form and relative situation of the
internal organs must necessarily be faithfully represented by the
external integument, even when it has acquired its greatest degree of
consolidation; thus the regions of the stomach, heart, branchiæ or
respiratory organs, &c. may be distinctly traced on the external shell.
Hence the fossil carapaces may afford important data regarding the
structure and economy of the extinct species. M. Desmarest[437] was the
first naturalist who successfully applied this _phrenological method_
to the investigation of the fossil crustaceans.
[437] Histoire Naturelle des Crustacés Fossiles; par MM. Alex.
Brongniart et Desmarest. 1 tom. 4to. Paris, 1822.
The fossil remains of Crustaceans consist of the calcareous covering
or carapace, with the articulated extremities, and, rarely, the
jaws and antennæ. For the most part, the specimens are mutilated,
and present only portions of the carapace, abdominal segments, and
detached claws; but in strata composed of very fine detritus, such as
the cream-coloured limestones of Solenhofen and Pappenheim, examples
often occur in the most beautiful state of preservation, appearing as
if the animals had been carefully embalmed in a soft paste, that had
quickly consolidated around them, and preserved them without mutilation
or blemish. In some examples, even the colour of the original remains.
The specimens found in hard limestones and coarse conglomerates are
generally mutilated, and, as the under surface of the carapace, and
the sternal plates to which the legs are attached, present more
irregularity than the dorsal portion of the shell, they are firmly
impacted in the stone, so as to render the development of some of the
most important characters difficult, if not impossible. The antennæ
and claws are often separated, or altogether wanting; the most common
relics being the pincers and the carapace, or united cephalo-thoracic
segments. The substance of the shell, which in the recent state
consists of phosphate and carbonate of lime, with gelatine or
cartilage, is commonly a friable carbonate of lime, tinged with oxide
of iron. These remarks apply more particularly to the crabs, lobsters,
shrimps, prawns, &c. Numerous species of the smaller crustaceans, as
the_ Cypris_, and the extinct family of _Trilobites_, occur in myriads,
and, in some formations, are the principal constituent of deposits of
great thickness and extent.
The remains of this class have been found throughout the vast series of
the fossiliferous strata. Extinct forms appear in prodigious numbers in
the most ancient formations, and are succeeded by genera which approach
more nearly to the more highly organized crustaceans. The Crab and
Lobster tribes are represented by certain species in the Lias, Oolite,
and Chalk; while in many of the Tertiary strata the existing types
prevail.
The London Clay, in the Isle of Sheppey, yields many beautiful examples
of the higher order of crustaceans, as the Crab, Lobster, &c. In the
Chalk these remains are more rare, but a few fine specimens have been
obtained. On the Continent, certain localities are extremely rich
in these remains. Upwards of sixty species were discovered by Count
Münster in the Jura limestone, at Solenhofen; and the Muschelkalk
of Germany has yielded several extinct genera. The beautiful state
in which these fossils occur, is exemplified in the specimen from
Solenhofen, figured in the frontispiece of this work; _Pl. I. fig. 2_.
Fossil Crabs.--Of the _brachyurous_, or short-tailed, crustaceans,
of which the common Crab is an example, and of the _Anomura_
(abnormal-tailed), there are remains of several genera in the Tertiary
deposits. The Isle of Sheppey is the most productive locality in
England. The carapaces of several kinds occur in the septaria and
nodules of indurated clay; the chelate hand-claws (_pincer-claws_)
are often found detached, and sometimes in connexion with the shield.
The most numerous specimens are referable to two species. One of them
(_Cancer Leachii_) is from two to three inches wide, and has a convex
shell, the surface of which is covered by minute punctations, with
three tubercles on each anterior lateral margin.[438] The carapace of
the other species is more distinctly lobed, and studded with aculeated
or spiny tubercles; it is named _C. tuberculatus_.[439]
[438] Hist. Nat. Crust. Foss. pl. viii. figs. 5 and 6.
[439] König, Icones Foss. Sect. _fig._ 54. These two species are now
referred to the genus _Zanthopsis_.
A species of Crab, characterised by its relatively large claws, is
common in the soft Tertiary limestone of Malta; and examples, in a fine
state of preservation, are often seen in cabinets; see _Wond._ p. 251.
I am not aware that vestiges of more than one genus of brachyurous
crustaceans have been observed in the British Secondary formations;
namely, the _Podopilumnus Fittoni_ (M‘Coy), from the Greensand of Lyme
Regis: but several small species belonging to the anomurous group have
been found in the Galt.
In the _Galt_ at Ringmer, a village near Lewes, I discovered, many
years since, four or five species of small crustaceans, which are
figured and described, _Foss. South D._ pl. xxiv.; their natural
relations were pointed out to me by the late eminent naturalist, Dr.
Leach. Specimens of two of the species have since been collected at
Folkstone, but as these are only the carapaces, no additional light has
been thrown upon the structure of the originals.
The smallest species consists of the carapace or cephalo-thoracic
segments, united into a transversely obovate, obscurely trilobate
shell, the surface of which is covered with minute irregular papillæ;
with four tubercles on each lateral portion, and an irregularly
tuberculated dorsal ridge (see _Lign. 168, fig. 1, 1a._); it
probably belongs to the genus Etyus; and I have named it _Etyus
Martini_, in honour of my friend, P. J. Martin, Esq., author of several
excellent Memoirs on the Geology of Western Sussex.
[Illustration: Lign. 168. Fossil Crustaceans: _nat._ _Galt._ _Near
Lewes._
Fig. 1. --Etyus Martini (G. A. M.): showing the empty carapace
or shell. _Ringmer._
1_a_.--The dorsal surface of the same.
2. --Corystes[A] Stokesii (G. A. M.). _Ringmer._
3. --Corystes[440] Broderipii (G. A. M.). _Ringmer._
3_a_.--The under surface of the same species, displaying the
sternal plates and the bases of the claws, three of which
are marked _a, a, a_.
]
[440] These two crustaceans are included in the fossil genus
Notopocorystes, established by Professor M’Coy, 1849.
There are two species that appear to have some relations with
_Corystes_, a genus which includes several recent crustaceans that
inhabit our shores, and are characterised by their elongated oval
shell and four antennæ, the external pair being long, setaceous,
and furnished with two rows of cilia. The tail is folded under the
body when the animal is in repose. They have ten legs, the anterior
pair _chelate_ (_with pincers_), the others terminating in an acute
elongated nail or claw. The fossils consist of the carapace, and one
example possesses the inferior or thoracic plates and the remains of
the bases of some of the legs (see _Lign. 168, fig. 3a_).
Notopocorystes Stokesii. _Lign. 168, fig. 2._--The carapace is relatively
wider than in most species of this genus; is has a strong dorsal ridge
of irregular oblong tubercles; the union of the cephalic and thoracic
segments is marked by a transverse undulated groove; there are three or
four tubercles on the surface of each lateral portion of the former,
and one on each of the latter. The whole surface is finely granulated.
The openings left by the attachment of the peduncles of the eye remain.
Notopocorystes Broderipii. _Lign. 168, fig. 3._--This species, like
the former, has a transverse undulated furrow, indicating the union of
the cephalic with the thoracic segments; the dorsal ridge is smooth,
and there are two tubercles on each lateral cephalic portion of the
shield. The carapace is longitudinally ovate, much depressed, with
three sharp points directed forwards on each margin of the anterior
part: the whole surface is finely granulated. In the specimen _fig._
3_a_ the sternal plates, with portions of the first joints of the
claws, remain; one example (figured _Geol. S. E._ p. 169) possessed
six or seven arcuate abdominal segments, which were turned under the
body.[441]
[441] I have described these small crustaceans somewhat minutely, and
have given them specific names, in the hope of directing the attention
of collectors to these highly interesting relics, and leading to the
discovery of more illustrative examples. See Foss. South D. pp. 96, 97.
The carapace or shell of the other crustacean observed in the Sussex
Galt (_Notopocorystes Bechei_) is of an orbicular inflated form (see
_Geol. S. E._ p. 169, _fig._ 3), and ornamented with twelve or thirteen
aculeated tubercles; its margin is dentated.
In the friable arenaceous limestone of the Cretaceous formation at
St. Peter’s Mountain, near Maestricht, the cheliferous claws of a
small kind of crustacean (_Mesostylus Faujasii_, _Wond._ p. 338),
are frequently discovered (and occasionally in the Chalk of Kent and
Sussex), but with no vestige of the carapace or shell. This curious
fact is explained by the analogy existing between the fossil claws and
those of the _Pagurus_, or Hermit-crab, whose body is only covered by a
delicate membrane, the claws alone having a calcareous covering; hence
the latter might be preserved in a fossil state, while no traces of the
soft parts remained. In the fossil, as in the recent claws, the right
arm is the strongest. There is no doubt that the crustaceans to which
the fossil claws belonged possessed the same modification of structure
as the recent (anomurous) Hermit-crab, and must have sought shelter
in the shells of the mollusks with which their durable remains are
associated.
[Sidenote: FOSSIL LOBSTERS.]
Fossil Lobsters.--The _macrurous_, or long-tailed, crustaceans, as the
_Lobster_, are distinguished from those of the former divisions by the
prolonged abdomen (or tail, as it is commonly termed), which forms
a powerful instrument of locomotion, and enables the animal to dart
backwards through the water with great rapidity; and this is furnished
with an appendage or tail, which none of the ambulatory crustaceans
possess.
Of the fresh-water species, the Cray-fish (_Astacus fluviatilis_),
and of the marine, the Lobster (_Astacus marinus_), are illustrative
examples. The remains of three macrurous species occur in the London
Clay of the Isle of Sheppey, associated with congenerous crustaceans;
and the segments of the tails (_post-abdomen_) are often well
preserved.
The Chalk contains a few species of the _Macrura_, which were first
discovered in the quarries near Lewes, and are figured in _Foss. South
D._ tab. xxx. xxxi.; they are among the most rare and delicate of the
fossils of the Cretaceous strata. These remains consist of the carapace
and claws, and rarely of the tail and antennæ, and are composed of
a friable earthy crust, which, when first discovered, is of a dark
chocolate colour, but quickly changes to a pale fawn, or reddish brown,
by exposure to the air. In the specimens obtained by breaking the
stone, the crustaceous covering remains attached by its rough external
surface to one portion of chalk, and on the corresponding piece are
sharp casts of the carapace and claws, having a glossy surface covered
with minute papillæ formed by the bases of tubercles or spines. Four
species have been observed.
Enoploclytia Leachii. _Lign. 169, figs. 1, 2, 3._--This is a long
delicate crustacean, having a pair of equal, slender, anterior chelate
claws, the fingers of which are long, attenuated, and armed with a
row of obtuse cylindrical spines. The surface of the hand-claws is
muricated, or covered with short erect aculeated tubercles. The pincers
in the specimen figured _Lign. 169, fig. 3_, are shorter than in
most examples. The carapace is elongated and sub-cylindrical, with a
dorsal ridge and two lateral furrows, indicating the normal division
of the cephalic and thoracic segments of the shield; the antennæ are
long, filiform, and setaceous (_bristly_), and are placed on squamous
peduncles (see _Lign. 169, fig. 2_).
There appear to have been five legs on each side; the anterior or
chelate pair are the most usual relics of this animal; of the other
claws and the branchiæ, but obscure indications have been obtained.
The abdominal segments are arcuate, and six or seven in number; their
surface is granulated; the appendage, or tail, is foliaceous and
marginate, with a few longitudinal ridges (see _Lign. 169, fig.
1_).[442] The claws of these crustaceans may be easily recognised by
their general aspect, and the length and straightness of the fingers or
pincers. In most examples traces remain of the tendinous expansion of
the muscles of the moveable claw (see _Lign. fig. 3_).
[442] See Foss. South D. p. 221, _et seq._ for further details.
[Illustration: Lign. 169. Fossil Crustaceans: _nat._ _Chalk._ _Lewes._]
Fig. 1.--Abdominal appendage, or tail, of Astacus[443] Leachii (G. A. M.),
with three abdominal segments.
2.--Part of the head of _Astacus Leachii_, with remains of the
squamous peduncles of the antennæ, and of the long setaceous
antennæ.
3.--Chelate claw, with part of the carpus, or wrist, of _Astacus
Leachii_.
4.--Chelate claw of Astacus[443] Sussexiensis (G. A. M.).
[443] These fossil Lobsters are now to be referred to Prof. M’Coy’s
genus Enoploclytia.
Enoploclytia Sussexiensis. _Lign. 169, fig. 4._--The claws of this
species are readily distinguished from the former by their broader and
stronger proportions, and spinous character; the pincers are strong and
tuberculated, and the moveable finger is more curved and shorter than
its opponent. The entire crust of this lobster is muricated, or beset
with spines and sharp tubercles.[444]
[444] Foss. South D. tab. xxx. _fig._ 3. In the beautiful work of
the late Mr. Dixon, on the Fossils of Sussex, there are figures of
very fine specimens of these two species of Enoploclytia (plate
xxxviii*.) with detailed descriptions by Prof. Bell (p. 344); but
unfortunately, from inadvertence, no reference is made to my former
drawings and descriptions of these fossil Lobsters of the Chalk,
and new names are given by the Professor; _E. Leachii_ appearing as
"Palæastacus macrodactylus," and _E. Sussexiensis_ as "P. Dixoni." I
need scarcely remind my readers that according to the established rules
of Nomenclature the _earlier specific names_ must be preserved; and
that, Prof. M‘Coy having already indicated the distinction of these
fossils from the recent _Astacus_ by providing an appropriate generic
appellation, these new names are altogether inadmissible.
Claws of other _Astacidæ_ have been found in the Chalk of Sussex and
Kent; one species in particular is distinguished from those previously
described by its short curved pincers, and granulated surface;[445] and
remains of other species of _Enoploclytia_, from near Cambridge and
Maidstone, are described by Prof. M’Coy.
[445] This species may be named _Astacus cretosus_, to indicate its
geological habitat.
The "Lobster-clays" in the Lower Greensand, or Neocomian, beds at
Atherfield afford numerous fine specimens of a small long-clawed
crustacean, allied to _Astacus_; a fine specimen is figured in the
_Geology of the Isle of Wight_, title-page vignette, and see page 232.
One or more species, apparently distinct from those of Atherfield, have
been discovered by Mr. Beckles in beds of clay that appear to occupy
the line of junction between the Wealden and Greensand, on the Sussex
coast, between Pevensey and Bexhill.
Imperfect claws of _Astacidæ_ have also been found at other places in
the Shanklin Sand; and I have collected from the Galt at Ringmer, the
abdominal segments of a small species, resembling _Meyeria ornata_,
_Lign. 170_.
[Illustration: Lign. 170. Fossil Crustacean. _Speeton Clay._
_Yorkshire._
Meyeria ornata: _nat._ (_Phillips and M’Coy._)]
The carapaces of two or three small _Astacidæ_, sometimes with the
abdominal segments attached, as in the beautiful fossil figured in
_Lign. 170_, are found in the Speeton Clay, near Scarborough. In
this example the post-abdomen and its appendages are entire, and
traces remain of the antennæ and some of the feet. These specimens
are commonly imbedded in masses of indurated clay, as the fern-leaves
in the Carboniferous ironstone, and are discovered by splitting the
nodules through their longest diameter. The carapace of another small
species (_Glyphea rostrata_)[446] occurs in the Oolite of Scarborough.
My friend, the Rev. J. B. Reade, has also discovered an example of this
species in that rich repository of organic remains, the Kimmeridge
Clay, at Hartwell, Bucks.
[446] This is the _Astacus rostratus_ of Prof. Phillips’s Geol. York.
vol. i. tab. 4, _fig._ 20.
A remarkable macrurous crustacean (_Eryon Cuvieri_) is found in the
Jurassic limestone of Solenhofen. Perfect specimens of this species
are occasionally seen in collections; it is distinguished by its very
large, flat, oval shell, with the front lateral margins strongly
dentated, and by its short setaceous antennæ; the front claws are as
long as the body, and armed with pincers; the post-abdomen consists of
six segments, terminating in a caudal appendage or tail.
In the United States several fossil crustaceans have been noticed in
the Cretaceous strata of New Jersey; some of which are said to be
related to _Pagurus_, and others to _Astacus_.
Fossil Prawns and Shrimps, of exquisite beauty, are found in the
lithographic limestone of Pappenheim: a specimen from that locality
(_Palæmon spinipes_) is figured _Wond._ p. 513: see also Frontispiece
of this work.
A large crustacean of the Shrimp family has been discovered by the Earl
of Enniskillen in the Lias of Lyme Regis.[447] Other specimens also of
Macrura, more or less perfect, have been obtained from the same rich
mine of organic remains: especially some in which the _branchiæ_, or
respiratory organs, remain; and a portion of the post-abdomen, or tail,
of a Cray-fish, as large as the common species.
[447] This beautiful fossil is figured and described by Mr. Broderip,
Geol. Trans, second series, vol. v. pl. xii. under the name of _Coleia
antiqua_.
[Sidenote: FOSSIL ISOPODOUS CRUSTACEANS.]
Isopodous Crustaceans. _Lign. 171._--Isopoda (_equal-feet_) is the term
applied to an order of crustaceans in which the body is composed of a
distinct head, and seven rings, each having a pair of equal feet; the
common _Oniscus_, or wood-louse, is a familiar example of a terrestrial
_Isopod_. This order includes many genera and species, some of which
nearly approach the extinct family of crustaceans (Trilobites) whose
remains abound in the palæozoic strata; and the parasitical Isopod,
_Bopyrus_, that infests the common Prawn, is closely related to certain
genera of Trilobites, hereafter described.
[Illustration: Lign. 171. Archæoniscus Brodiei. _Purbeck limestone._
_Vale of Wardour._ (_Drawn by S. P. Woodward, Esq._)
Impressions of the upper and under surfaces.]
One species of fossil _Isopod_ has been found in green fissile marl,
at Montmartre; and another in fine-grained limestone, probably, from
Pappenheim.[448] No fossil remains of this order had been noticed
in the British strata, until the discovery of the _Archæoniscus_ in
the Purbeck strata by the Rev. P. B. Brodie. The quarry in which
these relics were found is situated at Dallards, near the village of
Dinton, about twelve miles west of Salisbury. They are principally
distributed in a bed of light-brown and grey limestone, in the lower
part of which are numerous fresh-water bivalves (_cyclades_), and a
few small oysters. These Isopods often occur in clusters (see _Lign.
171_); the lenses of the compound eyes are sometimes detectable in the
limestone, and, rarely, attached to the head; traces of legs have been
observed, but no antennæ. In the same stratum the _elytron_ (sheath,
or wing-case) of a coleopterous insect was discovered. Mr. Brodie has
obtained specimens an inch and a half in length, and an inch broad.
These fossils appear to have been deposited tranquilly at the bottom of
the water which they inhabited, since they are usually found imbedded
with their legs downwards, and generally well preserved.[449]
[448] Nat. Hist. Crust. Foss. p. 138.
[449] See Brodie’s Fossil Insects, pp. 3 and 10.
The _Archæonisci_ also occur in the Purbeck insectiferous limestone of
Durlstone Bay, near Swanage, and have been discovered in strata of a
similar character at the Ridgway railway-cutting between Dorchester and
Weymouth, by the Rev. Osmond Fisher, of Dorchester.
Entomostraca.--The Crustaceans that we have above noticed belong to the
Sub-class Malacostraca; and we have now to describe some fossil genera
belonging to various divisions of the Entomostracous Crustaceans.
[Illustration: Lign. 172. Fossil. Limulus, in a Nodule of Ironstone:
1/2 _nat._
_Carb._ _Coalbrook Dale._]
Fig. 1. Limulus Rotundatus, the imprint of _fig._ 3.
2.--The nodule before it was broken.
3.--Limulus Rotundatus, (the corresponding portion of the nodule,
_fig._ 1,) showing the entire form of the carapace.
[Sidenote: FOSSIL LIMULUS.]
The Limulus (Mollucca or King Crab) is a genus belonging to that
Division of the Entomostraca termed Pœcilopoda and is abundant in
the seas of India and America. The carapace is crustaceous and of
a semilunar form, the head and thorax are blended together, and the
superior abdominal shield, which is composed of confluent segments,
appears like one piece, and has an indistinct trilobed character; the
last segment is prolonged into a three-edged, sharp, styliform weapon.
The Limulus has two reniform, compound eyes, composed of facets of a
peculiar form. The gills are disposed on lamelliform processes. It is
distinguished from all other crustaceans by the mastication of its food
being performed by the first joint of the thoracic legs which surround
the mouth, instead of by jaws.
[Illustration: Lign. 173. Limulus trilobitoides.
_Coal Measures._ _Coalbrook Dale._]
Very fine examples of a fossil species of this remarkable genus are
occasionally obtained from the lithographic stone of Solenhofen.[450]
In England three small species have been discovered in nodules of
ironstone and indurated clay, in the Carboniferous strata of Coalbrook
Dale, by Mr. Prestwich.[451] In one example (_L. Anthrax_[452]) two of
the legs are seen extending from under the body; in another species the
sharp, pointed process of the tail is well developed (_Buckl._ p. 396,
and tab. xlvi″.; see also _Lign. 173_). The specimen figured _Lign.
172_ is one of several examples which I obtained by breaking up nodules
from that celebrated locality. _Fig. 2_ represents the nodule unbroken,
and without any indication of its contents; by a well-directed blow
it was separated into two equal portions, _figs._ 1 and 3, in which
the carapace of the crustacean, and its marginal appendages, are well
displayed. The rounded form of the carapace, and the membrane which
appears to connect the spines, separate this species from all others.
[450] Hist. Crust. Foss. pl. xi. _fig._ 6.
[451] See Mr. Prestwich’s Memoir on the Geology of Coalbrook Dale,
Trans. Geol. Soc. second series, vol. v. part 3.
[452] Trans. Geol. Soc. second series, vol. v. pl. xli. figs. 1-4.
The Eurypterus and Pterygotus are palæozoic crustaceans, of large size.
They are regarded by Prof. M‘Coy and Mr. Salter as belonging to the
Pœcilopoda, and as differing from the Limulus chiefly in having the
segments of the abdomen freely articulating with each other.[453] The
_Eurypterus_ was first described by Mr. Dekay, in the United States,
probably from the Carboniferous system. The head is round, the thoracic
and cephalic portions of the carapace being blended together, and the
abdominal region is formed of eleven segments, with a caudal appendage.
It has two depressed, lunated eyes, remote from each other, and eight
feet, the anterior pairs furnished with _branchiæ_, and the hindmost
pair relatively larger than in any other crustacean. Two American
species are described; the one is five, and the other about four inches
long.[454] In the Carboniferous strata at Burdie-house, near Edinburgh,
and of Kirton, near Glasgow, a large species of this curious genius has
been found by Dr. Hibbert and Dr. Scouler; the length of some specimens
being estimated at from twelve to eighteen inches.[455]
[453] See Salter on Pterygotus, Quart. Journ. Geol. Soc. vol viii p.
387.
[454] Dr. Harlan, in Trans. Geol. Soc. Pennsylvania, vol. i. p. 96.
[455] See the elegant Memoir on the Fresh-water Limestone of
Burdie-house, near Edinburgh, by Samuel Hibbert, M.D. F.E.S.E.
Other species of _Eurypterus_ have been noticed in the Upper Silurian
rocks of Kendal, Westmoreland,[456] and of Kington, Radnorshire; and in
the Devonian of Russia.
[456] Pal. Foss. Cambridge, Appendix.
Pterygotus.--In the Old Red sandstone of Forfarshire, and other parts
of Scotland, the remains of this remarkable crustacean have been long
known to the quarry-men by the name of "_petrified Seraphims_;" from
an imaginary resemblance of the expanded post-abdomen to the usual
representations of those ideal beings! This genus is characterised by
the angular carapace, which forms a lozenge-shaped shield; and the
appendage of the post-abdomen, which, instead of being divided into
segments, as in most animals of this class, is a continuous flap. The
eye-pits on the carapace are like those of Eurypterus, but are very
large. The claws resemble those of the common lobster. The external
crustaceous covering is ornamented with circular and elliptical
markings, producing an imbricated or scaly appearance, the imprints
of which gave rise to the enigmatical "Seraphims" of the Forfarshire
sandstone. Some specimens indicate a total length of four feet![457]
[457] The Old Red Sandstone, or New Walks in an Old Field, by Hugh
Miller, p. 147. There are specimens in the British Museum from the
quarries of Carmylie.
Besides this Devonian species (_P. anglicus_), there is also a Silurian
species (_P. problematicus_), from Herefordshire.[458]
[458] See Quart. Journ. Geol. Soc. vol. viii. p. 386.
* * * * *
Several fossil genera of the Entomostracous Crustaceans belong to the
_Phyllopoda_ (_leaf-feet_), which constitute a subdivision of the
Branchiopoda (_gill-feet_). Of these perhaps the most remarkable is
the Dithyrocaris, first discovered by Dr. Scouler in the Carboniferous
shale near Paisley. This genus is allied to the recent _Apus_, and,
like it, has a broad, flat, thin carapace, easily divisible down the
middle of the back, and a lengthened tail or post-abdomen, with a
trifid termination. Six species have been found in the Carboniferous
deposits of the British Isles.
Ceratiocaris and Hymenocaris, which are related to the recent
_Nebalia_, are also of the Phyllopod group, and maybe said to resemble
a shrimp-like animal partly enclosed in a bivalve carapace, while its
tail is exposed, and either protruded, or turned beneath the body.
Of the first-mentioned genus there are three Upper Silurian species;
and of _Hymenocaris_ Mr. Salter has described a single species (_H.
vermicanda_) from the Lower Silurian (Cambrian) of North Wales.
The _Limnadiadæ_,--another Phyllopodous family, of which the recent
_Limnadia_ is the type,--are well represented in the older rocks.
These Crustaceans are also bivalved, but the body is wholly enclosed.
They are of small size. Estheria, a genus closely related to Limnadia,
occurs plentifully in the Wealden of Sussex and Germany, and in
the Lias of Westbury. Mr. Bean also has noticed a species (_E.
concentrica_) in the Oolite shell of Gristhorpe Bay; and the _E.
minuta_[459] is characteristic of the Keuper division of the Trias in
England and Europe.
[459] This was formerly described as a _Posidonomya_.
Leperditia and Beyrichia are other fossil genera belonging to the
_Limnadiadæ_. These little crustaceans were gregarious in their
habit, and, like Estheria, occur locally in great profusion. They are
characteristic of the Silurian deposits; the former being an abundant
Upper Silurian fossil in Europe and North America, and the latter,--a
very minute form,--both in the Upper and Lower Silurian.
The next group of Entomostraca that we have to notice belongs
to the Lophyropoda (_feet crested with bristles_), namely, the
Ostracoda (_shelled_). The recent genera, _Cypris_, _Cythere_, and
_Cypridina_,[460] are types of the three families of this group, and
are the existing representatives of numerous closely related forms that
occur in a fossil state.
[460] The student should consult Dr. Baird’s elegant and elaborate work
on the Natural History of the British Entomostraca (published by the
Ray Society), for information on the characters and habits of these
interesting little crustaceans and their numerous allies
[Illustration: Lign. 174. Fossil Cyprides. _Wealden._ _Sussex and Isle
of Wight._]
Fig. 1.--Cypris Valdensis: _magn._; showing the ventral aspect of
the united valves. _Cooksbridge._
1_a_.--Side view of the same, _magn._ The three small figures are
of the _nat. size_.
2.--Cypris Fittoni, _magn._ _Langton Green._
3.--Cypris tuberculata, _magn._ _Langton Green._
3_a_.--View of the same, showing the lower edges of the valves
united: the three small figures, _nat._
4.--Cypris granulosa, _magn._; view showing the hinge-line.
5.--A piece of Weald Clay, with Cyprides and Shells; _nat._
Cypris. _Lign. 174._--The animals of this genus belong to those
Crustaceans in which the covering of the body is not divided into
transverse segments, but consists of a large dorsal shield, having
the form of a bivalve shell. They are often very minute, and numerous
kinds swarm in our lakes and pools. The species of an allied genus,
named _Cythere_, the shells of which cannot always with certainty be
distinguished in a fossil state from those of _Cypris_, inhabit salt
or brackish waters. As the living _Cyprides_ are interesting objects
for microscopic examination, they are commonly shown in the exhibitions
of the hydro-oxygen microscope, and their appearance is therefore well
known. Two recent species are figured in _Ly._ p. 183. These animals
have the body enclosed in a bivalve, horny case, the two pieces being
united by a hinge-line. They have four feet, and two pairs of antennæ,
with a pencil of cilia at the extremities; and one compound eye. They
swim with rapidity, by means of their ciliated antennæ, and crawl about
actively on the water-weeds and other subaqueous surfaces. Like the
other crustaceans, they frequently moult or cast their cases, and the
surface of the mud spread over the bottoms of still lakes is often
covered with their exuviæ. The largest living Cypris (_C. clavata_)
does not exceed one-eighth of an inch in length. The fossil cases or
shells of Cyprides are found in considerable variety and in prodigious
numbers in certain Tertiary and Secondary strata, which appear to have
been deposited by fresh-water; as, for example, in the lacustrine marls
of Auvergne (_Ly._ p. 183), and the fluviatile clays and limestones of
the south-east of England. They have not been observed in any decidedly
marine beds; but Mr. Lonsdale discovered in the Chalk, by means of the
microscope, cases of crustaceans, that belong to the genus _Cythere_
(_Ly._ p. 26, figs. 21-24), the recent species of which inhabit the
sea. One or more species of Cypris have been observed in the older
British Tertiaries,--by Sir C. Lyell, in Hordwell Cliff (_Geol. Trans._
2d ser. vol. iii. p. 288), and by Mr. Prestwich at Hempstead Cliff
(_Brit. Assoc._ 1846); but in the Pleistocene deposits the Cypris and
its congeners abound, and of these Mr. R. Jones has enumerated nine
species (_Annals Nat. Hist._ 2d ser. vol. iii.). In many districts on
the Continent, the Eocene marls and clays abound in these remains.
Some of the fresh-water Tertiary strata of France contain myriads of a
Cypris (named _C. faba_, from its bean-like form) which was formerly
supposed, but erroneously, to be identical with a species found in
the Wealden. The laminated marls of Auvergne contain, between every
layer, countless myriads of the shells of Cyprides, through a depth of
several hundred feet; although each lamina of marl scarcely exceeds
the thickness of paper. Near Clermont, the green _cypridiferous_ marls
approach to within a few yards of the granite which forms the borders
of that ancient basin (_Ly._ p. 184). In the eastern portion of the
basaltic districts of India, Mr. Malcolmson has discovered two species
of Cypris, associated with fresh-water univalves and bivalves.[461]
In England the principal deposits of the Cyprides, are the clays
and limestones of the Wealden and the Isle of Purbeck,[462] to the
composition of which the relics of these minute beings have largely
contributed. Entire layers of their cases are found in the laminated
clays and marls on the southern shores of the Isle of Wight, at
Atherfield and Sandown Bay, where some of the Wealden beds emerge from
beneath the lower division of the Shanklin sand. Upon splitting the
clay in the direction of the laminæ, the exposed surfaces are found to
be covered with these minute bodies; as in the specimen, _Lign. 174,
fig. 5_.
[461] Geol. Trans. 2d ser. vol. v. pl. xlvii.
[462] On account of the distinctive characters of their
carapace-valves, M. Bosquet has suggested the appellation _Cypridea_ as
a generic name for the Cyprididæ of the Wealden and Purbeck beds.
The appearance of four characteristic Wealden Cyprides, of their
natural size and magnified, is shown in _Lign. 174_. The one named _C.
Valdensis_, or Wealden Cypris, by Dr. Fitton and Mr. Sowerby (fig.
1), is the most frequent, and occurs in numerous localities in Kent
and Sussex. A Cypris having the case studded with relatively large
tubercles (fig. 3), is found in many of the finer sandstones of
Tilgate forest; another, with the shell tuberculated, but divided by
a transverse ridge (fig. 2), indicating a rudimentary condition
of the segments which characterise the class, is certainly distinct
from the former, and can have no name more appropriate than that of
_C. Fittoni_. The other beautiful species (_C. granulosa_, fig. 4)
has the surface of the case covered with granules. One more species
has been observed in the Weald clay, at Sandown Bay and Atherfield
(by Mr. Lonsdale); it is distinguished by a short conical spine on
each valve, and is therefore named _C. spinigera_. In the Weald clay
at Resting-oak-hill, near Cooksbridge (_Geol. S. E._ p. 187), _C.
Valdensis_ is so abundant, that every thin flake is covered with its
white calcareous shells; and upon breaking the nodules and septaria
of reddish-brown ironstone which occur in that locality, myriads of
beautiful sharp casts of the cases are observable in almost every
fragment. They are associated with fresh-water bivalves and univalves
(_Cyclas_ and _Paludina_), and minute scales of fishes. The sandstone
at Langton Green, near Tunbridge Wells, which contains casts and
impressions of several species of fresh-water shells, abounds in
_Cyprides_; and the layers of argillaceous ironstone, interstratified
with the sandstone in one of the quarries, are particularly rich in
these remains. The surface of a recently broken slab is often covered
by minute, polished, oblong, convex bodies, which are the casts of
cypridean carapaces.
The Sussex marble is largely composed of the remains of these minute
crustaceans. Upon examining thin polished slices of this limestone
under the microscope, the cavities and interstices of the shells
are found to be filled with the shields of Cyprides, entire or in
fragments; and some specimens of the Purbeck marble equally abound in
these remains. The Purbeck marls, as well as the limestones, often
abound with Cyprides. According to Prof. E. Forbes, these belong to
several species, all more or less distinct from those of the Wealden
(_Brit. Association_, 1850). The Cyprides of the Wealden of Germany
have been figured and described by Dr. Dunker; and several of the
British forms are found there.
As the recent species inhabit still lakes, or gently running streams,
and not the turbulent waters of estuaries, we cannot doubt that the
strata in which these animals so largely predominate were deposited in
lakes or bays, communicating with the river which transported to their
present situation the bones and other remains of the colossal reptiles
of the Wealden. And the beds of fresh-water snails, with scarcely any
intermixture of other organic remains but the Cyprides, which are
spread over extensive areas in the Wealden and Purbeck districts,
appear to afford corroborative proof of this inference.
Four species of minute bivalved Entomostraca from the Carboniferous
deposits have been referred to _Cypris_: viz. _C. arcuata_, Bean, from
the Coal-shale at Newcastle; _C. inflata_, Murchison, Coal-measures,
near Shrewsbury; _C. Scoto-Burdigalensis_, Hibbert, Coal-measures at
Burdie-house, and Coal-shale at Derry; and _C. subrecta_, Portlock,
also from Derry, Tyrone.
Cythere.[463]--This animal differs but little from Cypris except in
having an additional pair of feet. In the Subgenus Cythereis the
valves are thick, oblong, and strongly hinged; thus differing from the
thin and more or less oval valves of the true Cythere and of Cypris.
Several species of _Cythere_ and its sub-genera occur in the Tertiary,
Cretaceous, Oolitic, Liassic, Permian, and Carboniferous deposits.[464]
[463] For description and illustration of this genus, see Baird’s
British Entomostraca, p. 163, &c.
[464] Consult M. Bosquet’s Memoir on the Tertiary Entomostraca of
Belgium and France; Mr. T. R. Jones’s Monograph of the Cretaceous
Entomostraca (Palæontographical Society), and of the Permian
Entomostraca, in Prof. King’s Monograph of the Permian Fossils
(Palæont. Soc.); and Prof. M’Coy’s Synopsis of the Characters of the
Mountain Limestone Fossils of Ireland.
Three species of Entomostraca, very closely related to Cypridina,[465]
from the Carboniferous rocks of Belgium, hare been figured and
described by M. De Koninck; one species from the Carboniferous rocks
of Ireland, by Prof. M’Coy;[466] and two species from the Cretaceous
limestone of Maestricht,[467] by M. Bosquet. The genera _Cyprella_ and
_Cypridella_ have been established by M. De Koninck for the reception
of some allied forms found in the Carboniferous strata of Belgium; and
Entomoconchus (M‘Coy) and _Daphnoidia_ (Hibbert) are allied British
Carboniferous forms.
[465] See Baird’s British Entomostraca, p. 176, &c.
[466] Under the name of _Daphnia primæva_.
[467] Under the generic appellation of _Cyprella_.
Trilobites.--Among the numerous petrifactions which are found in the
limestones in the neighbourhood of Dudley, in Staffordshire, there
are certain fossil bodies which, from their extraordinary form and
appearance, have for more than a hundred and fifty years been objects
of great interest to the naturalist, and of wonder to the general
observer, and have long been provincially termed _Dudley insects_, or
_locusts_.[468] By the earlier naturalists these fossils were referred
to fishes, to molluscs, and to insects, before their real character was
discovered. The most common type consists of a convex, oblong body,
divided transversely into three principal parts, and longitudinally
into three lobes, by two deep, parallel furrows; this last character
suggested the name _Trilobita_, or _Trilobites_, by which the family is
now distinguished by naturalists.
[468] Lhywd. Philos. Trans. for the year 1698.
[Illustration: Lign. 175. Trilobites. _Silurian Limestones._
Fig. 1.--Illænus perovalis. (_Murch. Sil. Syst._)
2.--Trinucleus Lloydii. (_Murch. Sil. Syst._)
3.--Calymene Blumenbachii: the upper surface of the
carapace, viewed from above. Dudley.
4.--The same, coiled up, and seen in profile.
4_a_.--The same, seen in front.
]
These fossils are the carapaces, or shells, of crustaceans, belonging
to an extinct family,[469] which comprises many genera, and numerous
species. Mortimer, Da Costa, Guettard, and Linnæus recognised the
crustacean character of this interesting, but obscure class of organic
remains: their true affinities, however, were first scientifically
determined by Alex. Brongniart.[470] Many memoirs on the _Trilobites_
have since been published by eminent Continental and American
writers;[471] and much light has been thrown on the subject by the
labours of Martin,[472] Parkinson,[473] Stokes, Phillips,[474]
König,[475] Dr. Buckland,[476] Sir E. I. Murchison,[477] and others.
The beautiful illustrations and interesting description of the
Trilobites in Dr. Buckland’s Bridgewater Treatise (_Bd._ p. 389, and
pl. xlv. xlvi.) must have rendered the reader familiar with the most
important facts relating to these extinct beings; but subsequent
discoveries have thrown additional light on their structure and natural
affinities. The works of M. Burmeister,[478] Mr. Salter,[479] Prof
M’Coy[480] and especially of M. Barrande,[481] should be carefully
referred to by the student in this branch of Palæontology.
[469] The Trilobites appear to have been related more nearly to the
Phyllopoda than to any other division of the Crustacea.
[470] Hist. Nat. Crust. Foss. Burmeister on Trilobites; Introduction.
[471] A Monograph on the Trilobites of North America, by Jacob Green,
M.D. Philadelphia, 1832.
[472] Petrificata Derbiensia.
[473] Organic Remains of a Former World, vol. iii. See Pictorial Atlas.
[474] Geology of Yorkshire; and Palæozoic Fossils of Devon.
[475] Icones Fossilium Sectiles.
[476] Bridgewater Treatise.
[477] Silurian System, chap, xlvii.
[478] Die Organisation der Trilobiten. 1843. Translation: Ray Society.
[479] In the Quarterly Journal of the Geological Society, and in the
Memoirs and Decades of the Geological Survey of Great Britain.
[480] Palæozoic Fossils in the Cambridge Museum.
[481] The Silurian System of Bohemia: the Trilobites.
In the Trilobites the head is distinct, and without antennæ, and the
feet are supposed to have been rudimentary, soft, and membranaceous:
the essential characters which separate them from all other
crustaceans, except _Bopyrus_ (a parasite on the branchiæ of the common
prawn), are, according to Mr. Macleay, the deficiency of antennæ,
and of lateral posterior abdominal appendages, and the presence of
evanescent feet. Like other crustaceans, the Trilobites were subject
to the process of metamorphosis during their early stages of life;
and M. Barrande has ascertained that one species, the _Saö hirsuta_,
appeal’s in no less than twenty different stages of development. In
its earliest, embryonic condition, it is a simple disk, and it passes
through various stages until it becomes a perfect adult trilobite,
having seventeen free thoracic segments and two caudal joints.
No less than ten genera and eighteen species were instituted by
palæontologists on _some_ of the forms only which this one species
presents in its different stages of metamorphosis, before M. Barrande’s
laborious and long-continued investigations gave him an insight into
the true relations of these various conditions of the same animal
to one another. This talented and indefatigable palæontologist has
arrived at like results with other Trilobites, and has been enabled
to add greatly to our knowledge of the natural history and geological
distribution of this interesting group of crustaceans. See Transact, of
the Sections, Brit. Assoc. 1849 and 1850; and _Trilob. Bohême_, pl. vii.
The _Trilobites_ have been arranged in numerous genera, the names of
which in a few cases are expressive of natural characters, but in
others have reference to the obscurity that still invests some parts of
the organization of these animals.[482]
[482] As, for example, Asaphus, _obscure_; Calymene, _concealed_;
Agnostus, _unknown_.
Calymene Blumenbachii. _Lign. 175, figs. 3, 4._--This is the
Trilobite so well known as the Dudley locust, or insect. It consists
of an ovate, convex, trilobed crustaceous shell, or case, and is found
either expanded, as in _Lign. 175, fig. 3_, with its under surface
attached to, and blended with, the limestone (_Wond._ p. 789); or
coiled up like an Oniscus, or wood-louse, as in _figs._ 4 and 4_a_.
The head is large, convex, rounded in front, with a broad border, and
divided into three lobes by two longitudinal depressions. The eyes are
two in number, compound, and have numerous facets; they are situated
on the sides of the head, remote from each other. The carapace is
deeply trilobed by two longitudinal furrows; the thoracic portion is
composed of thirteen segments; the caudal shield is small and nearly
semicircular. This species is from one to four inches in length. It
occurs from the Lower Llandeilo rocks up to the Upper Ludlow inclusive.
The structure here described may be regarded as the normal type, but
numerous and important modifications prevail in the different genera.
[Illustration: Lign. 176 Homalonotus dephinocephalus.
(_Reduced from_ pl. vii. _Sil. Syst._) _Upper Silurian._ _Dudley._]
In the genus Homalonotus, _Lign. 176_, the thoracic portion of the
carapace is but obscurely lobed, and consists of thirteen segments;
the abdominal is distinct from the thoracic, and formed of nine rings;
it terminates in a prolonged point. The _H. Herschelii_ is a large
Trilobite, very plentiful in the Upper Silurian schists of the Cape of
Good Hope.
In another genus, Asaphus (_Geol. Surv. Decade 2_), the carapace is
wide and much depressed; the middle lobe distinct, the cephalic portion
rounded in front, and terminating posteriorly in a sharp process on
each side. The eyes are compound, and each contains upward of six
thousand lenses, many of which remain in some examples.[483] Some
American species belonging to this group are of a gigantic size, as,
for example, the _Isotelus gigas_ (of Mr. Dekay), which is eighteen
inches long. In the Isotelus[484] the body is of an oval shape, and the
posterior angles of the head are rounded; the thorax is composed of
eight segments.
[483] Mem. Geol. Surv. Decade 2, pl. v. p. 2, note.
[484] _Isotelus_, i. e. equal extremities.
Another division of the Trilobites has the body contracted, and very
thick, and the abdomen large and scutiform, without any segmentary
divisions; the small crustacean (_Illænus perovalis_, _Murch._) _Lign.
175, fig. 1_, will serve to illustrate these characters.
The Trilobite called Bumastus by Sir R. Murchison (from its grape-like
form) presents a very curious modification of the normal type. Both the
head and caudal extremity are rounded, with no distinct longitudinal
furrows; and the whole surface of the carapace is covered by extremely
thin, apparently imbricated, lamellæ, the edges of which are undulated,
and the intermediate spaces studded with minute dots. The eyes are
smooth, and not granulose, as in Calymene. This genus is known in
England by the name of the Barr Trilobite, from its occurrence in the
limestone near Barr, in Staffordshire; it is sometimes five inches
long, and three and a half wide (_Geol. Surv. Decade 2_, pl. iii. and
iv.).
The genus Ogygia (_Bd._ pl. xlvi. fig. 9) is characterised by the
elliptical and depressed form of the carapace, its nearly balanced
extremities, and the prolongation of the buckler, or cephalic portion,
on each side, into slender spikes, distinct from the body; the thoracic
and abdominal regions are divided by two deep, longitudinal furrows,
into three lobes; there is also a straight, longitudinal groove, in
the front of the buckler (see figures and descriptions of _O. Buchii_,
_Geol. Surv. Decade 2_). The Trilobites of this genus are found in the
Lower Silurian rocks of North Wales and Ireland; they occur also in
great abundance in the slate rocks of Angers, and some species are more
than a foot in length.
Some species of the genus Phacops have long, pointed caudal appendages,
as the _P._ (formerly _Asaphus_) _caudatus_ (_Lign. 177_; _Bd._ pl.
xlv. figs. 10, 10′; and _Geol. Surv. Decade 2_, pl. i.). The eyes are
often well preserved, and each contains about 240 spherical lenses.
[Illustration: Lign. 177. Phacops caudatus. _Upper Silurian._ _Dudley._
The caudal extremity.]
Trinucleus. _Lign. 175, fig. 2_; _Ly._ fig. 432.--This genus
comprises several small forms which are found in the Lower Silurian
rocks of England, and occur in the equivalent deposits of Sweden,
Norway, and Russia.[485] In the _Trinucleus_, the cephalic shield is
obtuse, trilobed, rounded, and terminating in lateral spikes; and
its margin is marked by numerous pit-like depressions. There are
six body-rings or thoracic segments. The caudal shield is large and
somewhat triangular. There are no distinct eyes.
[485] Murch. Sil. Syst. p. 217.
Paradoxides. _Lign. 178._--The Trilobites of this genus are easily
recognised by the ends of the lateral segments of the thorax and
abdomen terminating in deflected points, which extend in spikes beyond
the membrane they supported, and particularly those near the tail,
which are much elongated; whereas in the other genera the lateral
points of the segments are united by a membrane, which often forms
a border beyond them. The cephalic buckler is semicircular, and its
lateral angles are lengthened out behind into two strong spines; it
is divided on the median line into four protuberances, by transverse
grooves. The thorax consists of from sixteen to twenty segments; the
abdominal buckler is generally very small and rounded. The animals of
this genus have the body much depressed, and the lateral lobes wider
than the middle lobe: some species are of considerable size, attaining
several inches in length.
[Illustration: Lign. 178. Paradoxides Bohemicus: _nat._
_Silurian._ _Bohemia._]
A very peculiar form of Trilobite (_Brontes flabellifer_, _Ly._ p. 348)
is found in the Devonian strata of the Eifel and South Devonshire; the
head, or cephalic region, is narrow, and has two lunated eyes; the
thoracic region is trilobed and short, and composed of about ten small
articulations; the abdominal very small, and bordered by segments,
which radiate and form a wide, fan-shaped expansion. Other species of
this genus occur in the Silurian rocks.
With regard to the under surface of the Trilobites much remains to
be known. No decided indications either of antennæ or extremities
have been discovered. In an American specimen, Mr. Stokes detected
a plate,[486] which appears to be a _labrum_, or upper mandible or
lip, resembling that of _Apus cancriformis_. This animal has a similar
labrum, "and lateral influted terminations of the shelly segments
of the body, with a distinctly trilobed _pygidium_ (tail or caudal
portion), and a prolonged tail: the feet being foliaceous, and the
abdomen merely covered by a membrane."[487] In the upper or dorsal
surface of the carapace the Trilobites approach certain _Isopoda_,
particularly in the characters of the buckler and eyes. Mr. Macleay
states that among the existing crustaceans there are certain genera
which individually possess some one or more of the characters, which
have been thought peculiar to the extinct Trilobites. Thus the
_Serolis_ (_Bd._ pl. xlv. fig. 6), and the _Bopyrus_, have a trilobed
form; the female _Cymothoæ_ have the coriaceous margin of the body,
and in some species are without eyes as are many of the Trilobites;
while the eyes of the males of some _Cymothoæ_ are composed of large
facets, and are situated on the back of the head, wide apart, as in
the _Calymene_; rudimentary feet, and the absence of antennæ occur in
_Bopyrus_; and lastly, the _Sphæroma_ has an onisciform body, and the
power of rolling itself up into a ball, like the Calymene (_Lign. 175,
fig. 4_). The analogy between the Bopyrus and the Barr Trilobite is
so close, that if the latter had a body with thirteen equal segments,
and short crustaceous feet, it would be in every essential particular
a male _Bopyrus_.[488] Burmeister regards the Trilobites as being
related to the _Branchipus_. From the absence of eyes in the female,
and their presence in the male of certain recent genera of crustaceans,
it is not improbable that a similar character may have prevailed in the
Trilobites, and that certain fossils referred to different genera, from
the presence or absence of eyes, may have been the males and females of
the same species.
[486] Geol. Trans, vol. ii. p. 208. See also _Bd._ pl. xlv, _fig._ 12;
and Burmeister, pl. vi.
[487] Murch. Sil. Syst. p. 665.
[488] Ibid. p. 667.
The habits of the Trilobites, as deducible from Mr. Macleay’s
exposition of their structure and affinities, must have resembled those
of the _Cymothoadæ_, some of which, like the Calymenes, coil themselves
up, and are not parasitical; while their close affinity to Bopyrus, and
the apparent absence of distinct crustaceous feet, imply that they were
to a certain degree sedentary. The flat under surface of their bodies,
and the lateral coriaceous margin of several species, which is so
analogous to that of the multivalve shell _Chiton_, render it probable
that they adhered by a soft, articulated, under surface, to the rocks
or sea-weeds. Their instruments of progression are unknown; whether
they moved by means of membranaceous feet, or by the undulations of
setigerous segments, like the earth-worm, or by wrinkling the under
surface of the abdomen, like the Chiton, are questions yet to be
determined. It is evident, from their longitudinally trilobed form, and
lateral coriaceous margin, that they had the power of firmly adhering
to flat surfaces; and while thus sedentary the thin but hard dorsal
crustaceous shell would protect them from the attacks of their enemies.
"The Trilobites, probably, like the Chitones, adhered in masses one
upon another, and thus formed those conglomerations of individuals
which are so remarkable in certain rocks; but it is not likely that
they were parasitical, since almost all the existing parasites that
adhere to other animals, have strong feet, armed at their extremities
with hooks for that purpose."[489] From the form of the _labrum_ of
the mouth (_Barrande_, pl. i. and ii A) it is inferred that they were
carnivorous, preying on naked mollusks, or on the annelides, with which
their remains are associated.
[489] Murch. Sil. Syst. p. 669.
As the compound eyes of the _Trilobites_[490] are similar to those
of existing crustaceans and insects (see _Wond._ p. 792), the highly
interesting and important fact is established, that the mutual
relations of light to the eye, and of the eye to light, were the
same in the remote epoch when the Trilobites flourished, as at the
present time; and that the condition of the waters of the sea, and
the atmosphere, and the relation of both these media to light, have
undergone no change through the countless ages that have elapsed since
the deposition of the Silurian strata.[491]
[490] The compound eyes in many specimens remain in a high state of
preservation. M. Barrande in the eye of a _Brontes palifer_ counted
30,000 lenses. See also Barrande, pl. iii.
[491] See Dr. Buckland’s eloquent and instructive commentary on this
subject, _Bd._ pp. 401-404.
* * * * *
Geological Distribution of Fossil Crustaceans. We have seen that the
Tertiary strata contain the remains of many of the highest organized
crustaceans; a few brachyurous, macrurous, and entomostracous genera
appear in the Cretaceous, Oolitic, and Liassic formations; whilst
the Isopodous _Archæoniscus_ and several species of Cypris occur in
the Wealden and Purbeck deposits. Some few Entomostraca have been
enumerated from the Trias and Permian.
One species of macrurous decapod has been found in the Muschelkalk of
Germany; and Mr. Prestwich’s "Apus dubius" (_Geol. Trans._ 2d ser. vol.
v. pl. xli. _fig._ 9), and Dr. Ick’s crustacean, noticed in _Journ.
Geol. Soc._ vol. i. p. 199, both from the Coal Measures of England,
are probably true Decapodous Crustaceans. With these exceptions not
a species of the numerous tribes of Crabs, Lobsters, &c. has been
observed in the older formations, though composed of such enormous
thicknesses of marine detritus, and containing countless myriads of the
relics of the inhabitants of the ocean.
A few species of _Limulus_, several _Cytheres_ and allied genera, and a
few Trilobites (_Phillipsia_ and _Griffithides_) belong to the strata
of the Carboniferous System. In the Devonian System we find some minute
entomostracans, the gigantic _Pterygotus_, and various Trilobites
(_Brontes_, _Cheirurus_, _Homalonotus_, _Phacops_, &c.); but it is the
Silurian rocks that constitute the grand mausoleum of those ancient
beings, the Trilobites.
There are about thirty genera of Trilobites found in the Silurian rocks
of Great Britain and Ireland. Many of these are common to the Upper
and Lower Divisions of that system; and some of them are met with both
in the Silurian and in the Devonian rocks, as _Phacops_, _Brontes_,
_Cheirurus_, _Harpes_, and _Homalonotus_. The _Calymene Blumenbachii_
(_Lign. 175_, _figs._ 3 and 4) ranges through the Ludlow and Wenlock,
to the Bala and Llandeilo formations. The _Phacops caudatus_ also
(_Lign. 177_), the _Cheirurus bimucronatus_,[492] and the _Encrinurus
punctatus_[493] extend from the Ludlow, to the Llandeilo formation.
The Upper Silurian rocks exclusively contain some peculiar forms, as
_Encrinurus variolaris_, _Bumastus Barriensis_, and several species
of _Acidaspis_. And the Lower Silurian has several distinct genera,
namely, the _Trinucleus_ (_Lign. 175, fig. 2_), _Ogygia_, _Agnostus_,
_Asaphus_, _Olenus_, _Remopleurides_, &c. One species of _Pterygotus_,
and one of _Eurypterus_, the _Ceratiocaris_ and _Hymenocaris_, and
several species of the minute bivalved Entomostraca (_Leperditia_ and
_Beyrichia_) are all that remain to be enumerated as constituting, in
company with the _Trilobites_, the Crustacean fauna of the ancient
Cambrian and Silurian seas.[494]
[492] In Murchison’s Silurian System this form is figured (pl. xiv.
figs. 8 and 9) and described as Paradoxides bimucronatus.
[493] This is described and figured as Asaphus tuberculatus in
Buckland’s Bridgewater Treatise, pl. xlvi. _fig._ 6.
[494] We have also to refer to the indications of the existence of
other large Silurian Entomostraca afforded by the magnificent series of
fossil foot-tracks lately brought to England by W. E. Logan, Esq., and
obtained by that gentleman from the Potsdam Sandstone (Lower Silurian)
of Eastern Canada. These foot-marks and trails have been determined by
Prof. Owen as being most probably referable to some large Crustaceans
of the _Limulus_ Group, and are named by him _Protichnites_. (See
drawings and descriptions in the Quarterly Journal of the Geological
Society, vol. viii.)
On Collecting Fossil Crustaceans.--The Crabs and Lobsters of the
argillaceous tertiary strata are generally imbedded in nodules of
indurated clay and septaria. On the shore beneath the cliffs on the
north of the Isle of Sheppey, and near Southend, specimens may be
observed in the nodules that have been exposed to the action of the
waves, the attrition to which they have been subjected having partially
worn away the surrounding stone, and displayed the enclosed fossils.
In these examples the carapace is occasionally seen on one side, and
the pair of pincer-claws on the other face of the boulder; the other
feet and the plates of the thorax may sometimes be developed in such
examples by chiselling away the enveloping mass. In the laminated marls
of the tertiary and other deposits, in which the minute crustaceans,
as the _Cyprides_ abound, thin slabs covered with these relics may
be easily extracted; and many of the tertiary clays and sands yield
_Cytheres_, together with _Foraminifera_ and other minute fossils, on
careful washing and examination with a lens.
The Chalk crustaceans, particularly those which are muricated, or beset
with spines and tubercles, as the _Enoploclytia Sussexiensis_ and _E.
Leachii_ (_Lign. 169_), require considerable patience and dexterity to
develope successfully. The crustaceous covering of the carapace and
claws adheres firmly to the chalk by the rough external coat, while
the inner, smooth, glossy surface as readily separates. Hence, upon
breaking a block of chalk containing portions of these crustaceans,
we find one piece exhibiting a chalk cast of the claw or carapace,
covered with tubercles or papillæ, that have been moulded in the bases
of the spines of the crust; and on the other portion the crustaceous
shell imbedded by its outer surface, and presenting the internal glossy
lining, beset with circular depressions, which are the bases of the
spines. This crust is exceedingly friable, and will flake off by a
very slight touch. To obtain specimens with the external characters,
it is necessary to proceed with great caution; and when indications of
a crustacean are observed in a block, the chalk should be chiselled
or sawn off to within half an inch of the surface of the fossil, and
the remainder of the stone be cleared away, piece by piece, by means
of a penknife or graver. By this process the fossils figured _Foss.
South D._ pl. xxix. xxx. xxxi. were developed. When a fine specimen
has been broken, and the shell is attached to one piece of the stone
and the cast to the other, it is possible to obtain an illustrative
example of the external surface, by cementing the pieces accurately
together with very thin hot glue; and, when firmly consolidated, the
chalk may be removed, and the spines, tubercles, and papillæ of the
crustaceous covering be developed by the method previously described. A
thin coating of mastic varnish will give durability to the crust, and
improve its appearance; but the rich brown colour it possesses when
first exposed soon disappears. The Crustaceans of the Galt are often
found amongst the argillaceous and pyritous nodules flung aside in
heaps where the Galt is used for brick-making.
The _Cytheridæ_ of the Chalk, Galt, Oolite, &c. are to be obtained by
disintegrating the matrix in water, and examining the debris, after
sifting, under a lens.
The Limuli of the Coal-measures often form the nuclei of clay nodules,
as in the example figured _Lign. 172_, in which _fig. 2_ represents the
nodule without any external indication of its contents, and _figs._ 1,
and 3, the same broken, and displaying the crustacean. Traces of the
legs, branchiæ, and other appendages, should be diligently sought for
in fossils of this kind, for they are more likely to be detected in
such specimens than in those found in limestone. It is possible that
polished sections of the coiled up examples of Trilobites (_Lign.
175, fig. 4_) would throw some light upon the nature of the hitherto
undiscovered organs of locomotion and respiration of this extinct order
of Crustaceans.
A FEW BRITISH LOCALITIES OF FOSSIL CRUSTACEANS.
Abberley. Silurian: _Trilobites_ and _Beyrichia_.
Aberystwith, neighbourhood of. Silurian: _Trilobites_.
Arundel, Sussex. Chalk-pits in the vicinity. Astacidæ and Cytheridæ.
Atherfield, Isle of Wight. Wealden: _Cyprides_ in clay (_Lign. 174_).
Barr, Staffordshire; limeworks at Hay Head. Silurian: _Trilobites_,
particularly of the genus _Bumastus_.
Bewdley, Shropshire. Silurian: _Trilobites_.
Bolland, Yorkshire. Carboniferous Limestone: _Trilobites_ (_Cyclus_,
_Phillipsia_).
Burdie-house, near Edinburgh. Fresh-water coal-measures. _Cyprides_
and _Eurypteri_.
Burham, near the banks of the Medway, Kent. Quarry of Mr. W. Lee, a
good section of the lower Chalk: fine _Crustaceans_.
Coalbrook Dale. Coal-measures and Silurian. _Limuli_ and _Trilobites_.
Coniston, Lancashire. Silurian: _Trilobites_.
Dinley, Wilts. Purbeck. _Isopoda_ (_Lign. 171_) and _Cyprides_.
Dover. In the lower Chalk, _Astacus_ (_Enoploclytia_) _Sussexiensis_,
&c.
Dudley. Upper Silurian: _Trilobites_ in abundance.
Durlstone Bay, near Swanage. Purbeck: _Cyprides_ and _Isopoda_.
Folkstone, Kent. In Galt: small Crabs (_Lign. 168_), and numerous
_Cytheres_.
Grays, Essex. Pleistocene: _Cyprides_.
Gristhorpe Bay, Yorkshire Oolite: _Astacidæ_.
Hastings, Sussex, neighbourhood of. Wealden: _Cyprides_.
Hollington, near Hastings. Wealden: _Cyprides_.
Hordwell Cliff, Hampshire. Upper Eocene: _Cyprides_.
Kildare, Ireland. Carboniferous and Silurian: _Trilobites_.
Langton Green, near Tunbridge Wells. Wealden: _Cyprides_.
Lewes, Sussex. In the Chalk-pits of the vicinity: Astacidæ (_Lign._
169), and other Crustaceans.
Llandeilo, Caermarthenshire. Lower Silurian: _Trilobites_, _Trinuclei_.
Lyme Regis, Dorset. Green Sand: Hoploparia. Lias: _Coleia_.
Malvern Hills. Lower Silurian. _Trilobites_ (_Olenus_).
Meifod Hills, Montgomeryshire. Silurian: _Trilobites_.
Mount Pleasant, Caermarthen. Silurian: _Trilobites_.
Newton Bushel. Devonian: _Trilobites_ (_Brontes_).
Rhiwlas, near Bala, North Wales. Lower Silurian: _Trilobites_.
Ringmer, near Lewes. In Galt: small _Crabs_, &c.
Sandown Bay, Isle of Wight. _Cyprides_, in Weald Clay.
Scarborough. Oolite: _Astacidæ_, in clay nodules.
Sheppey. London Clay: _Lobsters_ and _Crabs_.
Steyning, Sussex. In Chalk-marl: _Lobsters_, &c.
Tyrone, Ireland. Carboniferous and Silurian: _Trilobites_.
Wenlock, neighbourhood of. Upper Silurian: _Trilobites_.
Westbury, Gloucestershire. Lias: _Estheria_ and _Cyprides_.
Wilmington, near Marton, Salop. Silurian: _Trilobites_.
Wistanstow, Salop. Lower Silurian: _Trilobites_.
Worthing, Sussex. Neighbouring Chalk-pits. _Lobsters_, &c.
FOSSIL INSECTS, SCORPIONS, AND SPIDERS.
From the Crustaceans we pass by a natural transition to the other
Articulata, viz. the Arachnida (Scorpions and Spiders) and the Insecta,
in the last of which "the highest problem of animal mechanics is
solved, and the body and its appendages can be lifted from the ground
and propelled through the air" (_Owen_). The skeleton in these animals,
as in the Crustaceans, is chiefly external, and consists of a hard
shell or case (composed of a peculiar substance, termed _chitine_),
divided into segments, and furnished with articulated or jointed
hollow extremities. The head is distinct, and has a pair of compound
eyes, and of jointed antennæ. To the segments that form the thorax the
legs are attached, and these consist of three pieces in the hexapods
(insects with six feet), each supporting a pair of feet. The wings
in the flying insects are attached to the middle and third thoracic
segments. The legs, or articulated appendages, are hollow, as in the
Crustaceans, and contain the muscles and other soft parts. The generic
and other distinctions adopted by naturalists, to facilitate the study
of this most numerous division of the animal kingdom, are founded on
the structure and configuration of the antennæ and wings. The latter
consist of flat membranous expansions, supported by hollow tubes or
nervures; and in some orders consist of one pair, and in others of
two. In burrowing insects, as the Beetle, the front pair of wings
constitutes a hard case (_elytron_), which covers and protects the
membranous posterior pair, when the animal is in repose or walking. The
modifications of the wings furnish the characters by which the class is
divided into orders. Thus the _Coleoptera_ (sheathed-wings) comprise
the beetles and other burrowing insects, in which the membranous
wings are folded transversely beneath the elytra, or wing-cases. The
_Orthoptera_ (straight-wings), those with two pairs of wings, of which
the anterior encase the others, the posterior being membranous, and
folded longitudinal during repose; as the Earwig, Cockroach, Mantis,
and Locusts. _Neuroptera_ (nerved-wings), those with two pairs of
transparent reticulated wings, as the Libellula, or Dragon-fly, the
Ephemera, and the Termites. _Hymenoptera_ (membranous-wings), with
simply veined membranous wings, as the Gall-flies, the Bee, &c. The
Cicas, Aphis, and Coccus constitute the somewhat anomalous group
termed _Homoptera_ (equal-wings), in which the anterior pair of wings
are usually similar to the posterior in consistence, and shut up in a
roof-like manner. The _Heteroptera_ (different-wings) include the Nepa,
Notonecta, &c. and have the anterior wings coriaceous at the base,
membranous towards the point, and shutting up nearly horizontally,
partly lapping over one another. _Lepidoptera_ (scaly-wings) have
wings covered with scales, as the Butterfly and Moth. In the _Diptera_
(two-wings) the anterior pair of wings only are the instruments for
flying, and the hinder pair are reduced to mere clavate appendages, as
the Gnat and Fly. The Phryganeæ (Caddis flies) constitute the order of
_Trichoptera_ (hairy-wings), related to the Neuroptera, but resembling
the Lepidoptera in the distribution of the nervures of the wings, and
in many other characters. Lastly, there remain the Wingless Insects,
divisible into three orders, of which the Flea, the Parasites, and the
Podura are respectively the types. With these few remarks on those
durable parts of the structure of Insects which their fossil remains
generally present, we must quit this part of the subject, and enter
upon the examination of the relics which are the immediate objects of
our present inquiry.
From the enduring nature of the elytra, segments, and articulated
extremities of insects, the fossil remains of animals of this class
might naturally be expected to abound in lacustrine and fluviatile
deposits; this, however, is not the case, and except in a few favoured
localities, fossil insects are seldom met with, and good specimens
rank among the most rare and interesting of the organic remains of
the Secondary formations. In certain Tertiary beds, as at Œningen,
and Aix in Provence, insects of numerous species and genera have been
discovered; and the cream-coloured limestone of Solenhofen, among its
numerous other treasures, has yielded some fine examples of this class.
The strata in which remains of insects have been found in England[495]
are the Tertiary clays of the Bagshot series, the Hastings beds,
Purbeck marls and limestones, Kimmeridge Clay, Oxford Clay, Forest
Marble, Stonesfield Slate, Upper and Lower Lias, and the Coal Measures.
[495] Palæontologists are particularly indebted to the Rev. P. B.
Brodie, F.G.S. for his compendious and valuable "History of the Fossil
Insects in the Secondary Rocks of England" (8vo. 1845); and to J.
O. Westwood, Esq. the eminent Entomologist, for the very important
and interesting Observations on the Insect Remains, prefixed to the
above work. In an interesting paper on the Geology of the vicinity
of Ilminster, C. Moore, Esq. has noticed the numerous Insect remains
of the Upper Lias of that place. Prof. E. Forbes and W. R. Binfield,
Esq. have discovered Insects in the Hastings series; and Mr.
Binfield, besides having most successfully searched the Upper Lias of
Gloucestershire, has also detected some specimens in the Lias at Lyme.
Lastly, Mr. Morris has found Insects in the Upper Lias in Lincolnshire.
ARACHNIDA.
Fossil Scorpion. (_Bd._ pl. xlvi′.)--The discover of a fossil Scorpion
in coal-shale, associated with leaves, by Count Sternberg, and of
Spiders in the limestone of Solenhofen, by Count Münster, proves the
existence at a very remote period of both these insectivorous families
of _Arachnidans_, or spiders (_Bd._ p. 405). The fossil Scorpion was
found in a block of argillaceous shale, at Chomle, in Bohemia. It lies
imbedded amidst the carbonized remains of leaves, and a large trifid
carpolithe or seed-vessel (see _Bd._ pl. xlvi′.): by a fortunate
separation of the shale, the back or dorsal carapace is shown on one
surface; and the thorax, with five or six legs attached, and the
abdominal segments, are exposed on the other, together with a fragment
of the tail of another and larger Scorpion. The head and eyes, one
of the jaws with teeth, and a portion of the skin remain (_Bd._ pl.
xlvi. figs. 3, 4, 5, 6). The horny covering seems to have undergone no
change; it is still elastic and transient, and consists of two layers,
both retaining their texture, and structure, and exhibiting under the
microscope hexagonal cells divided by strong partitions.
Fossil Spiders.--With the numerous insects preserved in the gypseous
marls at Aix, of which we shall treat hereafter, Spiders are
occasionally found. A beautiful example, showing the under surface of
a small spider, with the papillæ of the spinning organs protruded by
pressure, from the cabinet of Mrs. Murchison, is figured, _Bd._ pl.
xlvi′. fig 12 In the beautiful lithographic stone of Solenhofen the
remains of spiders are not unfrequent.
INSECTA.
Fossil Neuroptera.--Of this order, the insects of which are
distinguished by their four finely reticulated membranous wings,
several fossil species have been found. Some of these are referable to
the family Libellulidæ;--insects so well known from their light and
elegant figure, their beautiful and variegated colours, their large
lustrous wings, and the velocity and gracefulness of their motions.
[Illustration: Lign. 179. Fossil Libellula, or Dragon-fly. _Solenhofen._
(_Drawn by Mr. Joseph Dinkel._)
In the cabinet of the late Marquess of Northampton.]
Fossil Libellulidæ. _Lign. 179._--Of the highly organized family of
carnivorous insects, the _Libellulidæ_, five or six specimens have been
discovered in the lithographic limestone of Solenhofen; a beautiful
specimen from that locality is represented, _Lign. 179_. In this
example both pairs of wings remain, but one wing is pressed down
beneath the abdomen: the nervures of the wings are admirably preserved.
A few examples of the remains of this family have been found in the
British strata. One species of _Libellula_ and one of _Æshna_ have
been found by the Rev. Mr. Brodie in the Purbeck beds of the Vale
of Wardour. Two species of _Libellula_,[496] two of _Æshna_, and
some other allied species have been obtained by Messrs. Strickland,
Buckman, Binfield, and Brodie from the Lias. The wing of the _Æshna
liassina_, discovered in the Lias, near Binton, in Warwickshire, by Mr.
Strickland, is two inches and ten and a half lines in length, and eight
and a half lines in its greatest breadth, being one-third larger than
the wing of the largest British species. See _Wond._ _Lign._ 119, and
p. 528.
[496] A very interesting specimen of fossil _Libellula_, discovered by
the Rev. Mr Brodie in the Upper Lias near Cheltenham, is figured in the
Quarterly Geol. Journal, for 1848, vol. v. pl. v.
Fossil Corydalis. _Lign. 181, fig. 2._--The wing of a remarkable
fossil Neuropterous insect was discovered by me in a nodule of
ironstone, from Coalbrook Dale, and mistaken for a leaf. The specimen
consists of one wing, which, as M. Audoin first ascertained, closely
resembles that of the living _Corydalis_ of Carolina; see _Lign. 181,
fig. 2_. The membranous structure and the distribution of the nervures
are distinctly preserved; on the portion figured the surface of the
wing lies in relief on the stone; and on the corresponding part of
the nodule, a sharp imprint remains,[497] I have named this fossil in
honour of the eminent French savant, M. Alex. Brongniart.
[497] This specimen is now in the collection of the British Museum.
Wings of _Corydalis_ have also been found in the Purbeck beds of the
Vale of Wardour, by the Rev. Mr. Brodie, who has also discovered
remains of _Phryganeidæ_ and a _Termes_ in the same group of strata.
Panorpa ? Liassica. _Lign. 180._--In the Lias, on the banks of the
Severn, at Wainlode Cliff, Gloucestershire, specimens of minute
neuropterous wings have been discovered. I subjoin accurate figures
of two specimens in the cabinet of the Geological Society; they are
represented twice the natural size; they resemble the wings of a recent
genus of Neuroptera, termed _Panorpa_; particularly _P. Germanica_. The
transverse lines are not fractures, but nervures, and are faithfully
copied from the originals.
To the above notice of British fossil neuropterous insects, I may add
that the wing of a large species (_Hemerobioides giganteus_) has been
discovered by Dr. Buckland in the Stonesfield slate.
[Illustration: Lign. 180. Wings of Neuropterous Insects. _Twice nat.
size._
(_Drawn by S. P. Woodward, Esq._)
_Lias._ _Wainlode Cliff._
Portions of the anterior wings of a species resembling Panorpa.]
[Illustration: Lign. 181. Fossil Wings of Insects.
(_Drawn by S. P. Woodward, Esq._)]
Fig. 1.--Elytron, or wing-case of Buprestis Bucklandi, _Great
Oolite_; _Stonesfield_.
2.--Wing of Corydalis Brongniarti. (G. A. M.) _Carboniferous_;
_Coalbrook Dale_.
Fossil Coleoptera.--The _elytra_ or wing-cases of coleopterous insects
have long since been noticed in the oolitic slate at Stonesfield, near
Oxford; a locality celebrated for the only mammalian relies hitherto
discovered in the Secondly strata of England. The Stonesfield elytra
are always found detached; in no instance, I believe, has any other
part of an insect been observed, except a single leg of a _Curculio_
(_Bd._ pl. xlvi′. _fig._ 10). The specimen figured _Lign. 181, fig.
1_, displays the usual characters of the largest species. These fossils
are of a reddish-brown colour, with a finely granulated surface; there
appear to be four or five species, all of which belong to _Buprestis_,
a family of beetles remarkable for their splendid metallic lustre.
Remains of _Coleoptera_ occur in the Tertiary clays near Corfe,
Dorset,[498] and in the Lias of Worcestershire and Gloucestershire; and
in the Danby oolitic coal-pits, in the eastern moorlands of Yorkshire,
the elytra of beetles have also been discovered, by Mr. R. C. Taylor
(_Bd._ vol. ii. p. 78).
[498] See Notice by the Rev. Mr. Brodie, Quart. Geol. Journ. vol. ix.
p. 51.
A most remarkable fossil of this kind is described by Dr. Buckland;
a unique specimen of _Buprestis_, from Japan, about an inch long,
_converted into chalcedony_, with the antennæ and portions of the legs
finely preserved. The surface of this insect is covered with clusters
of minute concentric rings of chalcedony; an appearance common in
silicified shells. Associated with this fossil, were fragments of
silicified wood, bored with tubular cavities, apparently by the larvæ
of insects of this family; and within these cavities was a quantity of
dust produced by the boring, also converted into chalcedony (_Bd._ vol.
ii. p. 78).
Of the Curculio, a genus of coleoptera distinguished by their splendid
elytra, of which the _Diamond Beetle_ is a familiar example, the
remains of two species have been discovered in the nodular ironstone
of Coalbrook Dale, by Mr. W. Anstice, and are figured and described by
Dr. Buckland (_Bd._ vol. ii. p. 76; and pl. xlvi′. figs. 1, 2). In one
of these specimens (_Curculioides Ansticii_), with the exception of the
rostrum and anterior part of the head, all the essential characters of
the insect are displayed; namely, the elytra, thorax, and six legs, the
hindmost of which exhibits the enlarged femur, or thigh, a character
peculiar to the _Curculionidæ_. The legs possess a tufted appearance,
which that eminent entomologist, Mr. Curtis, conceives may have been
caused by fungi, after the death of the animal, as often happens in
tropical climates. In the other example (_C. Prestvichii_), the insect
lies on its back, with the left side raised upwards, and exhibiting a
portion of the external surface of the left elytron; there are remains
of the antennæ, and indications of the proboscis and of the legs.
[Illustration: Lign. 182. Insectiferous Limestone. _Purbeck._
(_Magnified six diameters._)]
_a, b._ Membranous wings of the _Corydalis_ type.
_c._ Punctate-striate elytron of a Beetle.
_d._ Elytron of a Beetle, with a smooth surface.
_e._ Smooth elytron, the upper part impressed with
transverse lines.
The _Orthoptera_, _Homoptera_, and _Diptera_ are also represented
in the Lias of Gloucestershire, and in the Purbeck strata of the
Vale of Wardour, by numerous species, which have been enumerated,
and mostly discovered, by the Rev. Mr. Brodie.[499] This observer
has, indeed, been very successful in his researches in the latter
locality, for in the deposits of limestone and marl which yielded the
isopodous crustaceans, previously described (p. 521, _Lign. 171_), he
has discovered the remains of several orders of insects, and states
that, for abundance and variety of specimens, the beds may be said to
resemble the Tertiary marls of Aix and Œningen. These remains were
obtained from a quarry at Dinton, about twelve miles west of Salisbury.
They consist chiefly of _Coleoptera_, with the remains of _Neuroptera_,
_Trichoptera_, and _Homoptera_, and of several species of _Diptera_.
In the cream-coloured laminated Purbeck marls that axe exposed in
Durlstone Bay (about one mile from Swanage) insectiferous beds have
been found by the Rev. O. Fisher and Prof. E. Forbes, which are the
equivalents of those of the Vale of Wardour; and similar beds were met
with in the cutting of the railway through the Ridgway Hill, between
Dorchester and Weymouth.
[499] See Brodie’s Fossil Insects.
In a quarry on the road-side between the village of Stone and Hartwell,
Bucks, the Portland Oolite is covered by the Purbeck marls; in these
latter remains of Insects occur, together with scales and teeth of
small Fishes, and abundance of _Cyprides_.
All the British localities of fossil insects have now been alluded to;
but on the Continent, independently of the celebrated limestones of
Solenhofen, to which reference has been made, p. 550, there are several
tertiary deposits exceedingly rich in these interesting fossils.
[Sidenote: FOSSIL INSECTS.]
Fossil Insects of Aix, in Provence.--The town of Aix is situated in
the lowest part of a deep valley, the immediate flanks of which are
composed of a thick fresh-water formation, lying unconformably upon
strata of Jura limestone. The fresh-water series consists of white and
grey calcareous marls, calcareo-siliceous grits, and beds of gypsum;
and the quarries formed in the latter rock have long been celebrated
for the prodigious quantity of fish and plants which they contain.
M. Marcel de Serres first made known the great abundance of insects
in these gypseous marls, and has enumerated nearly seventy genera,
chiefly of the Coleoptera, Diptera, and Hemiptera; they are mostly
referable to European forms, and to existing genera. An interesting
Memoir on these strata, by Sir R. Murchison and Sir C. Lyell,[500]
first directed the attention of the English reader to these beautiful
fossils. In _Wond._ p. 261, an epitome of this valuable communication
is given, and five specimens of insects are here figured, which will
convey some idea of their forms and perfect state of preservation.
[500] Edinburgh New Philosophical Journal for October, 1829.
[Illustration: Lign. 183. Fossil Insects. _Tertiary._ _Aix in
Provence._]
Fig. 1.--Tettigonia spumaria.
2.--Mycetophila; the body distended by pressure.
3.--Lathrobium.
4.--Allied to Penthetria holosericea. The hinder legs are
broken off, and one of them reversed, so that the _tarsi_
nearly touch the thigh; the _palpi_ are long and perfect;
the antennæ are remarkably distinct.
5.--Liparus; resembling L. Punctatus.
Fossil Insects of Œningen.--In the immediate vicinity of Œningen, near
Constance, on the banks of the Rhine, there is the basin of an ancient
lake, filled up with marls and limestones, presenting a fine example
of a lacustrine formation, and abounding in fossil Fishes, Reptiles,
Plants, Shells, Crustaceans, and Insects.[501] These Insects are often
in an admirable state of preservation, and occur in the different
stages of larva, pupa, and imago. The pupa of a _Libellula_ shows the
mask, insertion of the legs, and the spiracula. Some belong to genera,
the species of which frequent marshy plants of the same kind as those
which are found associated with the insects; and it seems probable that
they fell into the lake from the plants which grew on its borders,
and became enveloped in the fine mud or sediment. Numerous species of
several genera of Ants also occur in these deposits of Œningen and at
Radoboj in Croatia.[502]
[501] See the Memoir by Sir R. I. Murchison on the lacustrine formation
at Œningen, near Constance, Geol. Trans, new series, vol. iii. p. 277.
[502] See Prof. O. Heer’s Memoir, translated in the Quart. Journ. Geol.
Soc. vol. vi. pt. ii. p. 61; and his History of Insects, ibid. p. 68.
[Sidenote: FOSSIL CADDIS-WORM.]
Fossil Larvæ of Phryganea. _Ly._ p. 185.--The _Caddis-worm_, so well
known to all the brethren of the angle, is the larva of the winged
insect termed _Phryganea_, and is abundant at the bottom of fresh-water
streams and lakes; the cases, like those of the marine _Sabella_
(p. 385, _fig._ 6), are always studded over with extraneous bodies,
cemented together by a glutinous secretion to the silken integument,
or case, which encloses the lava. Some species are coated with pieces
of stick or straw, others with minute shells, as planorbis, bithinia,
and the like; and when the larvæ have passed into the perfect state,
their cases, or _indusiæ_, remain. Many of the Tertiary fresh-water
limestones of Auvergne are almost wholly composed of the _indusiæ_
of Caddis-worms, cemented together by calcareo-siliceous matter into
stone, which is employed for building, and is called indusial limestone
(_Wond._ p. 273). These limestones are associated with marls abounding
in fresh-water shells and cyprides; the whole assemblage presenting
all the stratigraphical and zoological characters of a lacustrine
formation. "If," says Mr. Scrope,[503] "we consider that repeated
strata, of five or six feet in thickness, almost entirely composed of
these tubes, once extended over a district presenting a surface of many
hundred square miles, we may have some idea of the countless myriads
of minute beings which lived and died within the bosom of that ancient
lake."
[503] On the Geology of Central France, by G. Poulett Scrope, Esq. 4
to. 1827.
On Collecting Fossil Insects.--The localities in which the British
collector may reasonably expect to discover fossil remains of
Insects, are Stonesfield, where the elytra of beetles are by no
means scarce,--Coalbrook Dale, in which relics of this class are
sometimes, but very rarely, found in the ironstone nodules,--Bedford,
Warwickshire, and the Wainlode and Aust Cliffs, for Lower Lias
insects,--Dumbleton and Ilminster, for Upper Lias insects,--Dallards,
near Dinton, and Stone, near Aylesbury, and the exposures of similar
beds in Dorsetshire, for the Purbeck insects.
The white clays belonging to the Bagshot series of Bournemouth, Poole,
and Corfe, so rich in beautifully preserved leaves and other parts of
plants, should be carefully searched for insect remains, since these
clays at Creech, near Corfe, have already afforded a few specimens.[504]
[504] Quart. Geol. Journ. vol. ix. p. 51.
At page 549 a few other English localities yielding these delicate
and very interesting fossils are also indicated as having been lately
discovered by some of our most acute and active geologists.
Should the student visit the celebrated sites of these fossils in
France and Germany, namely, Aix, Œningen, Solenhofen, &c., he will have
but little difficulty in obtaining an interesting series, at a moderate
expense.
The marls and limestones in which insects occur are often of a
laminated character, and in general readily split asunder in the
direction favourable for the display of the insects. In some examples,
only the form of the animal is seen through a thin opaque pellicle of
calcareous earth, which may be removed by a penknife or graver, and the
wings, elytra, antennæ, legs, &c. will thus be disclosed. A very thin
coating of mastic varnish heightens the colours of such specimens, and
renders them more durable.
CHAPTER XIV.
FOSSIL ICHTHYOLOGY; COMPRISING THE SHARKS, RAYS AND OTHER PLACOID
FISHES.
[Illustration: Lign. 184. A group of Fossil Fishes. _Tertiary._ _Aix._
Lebias cephalotes (_Agassiz_).]
Ascending from the two grand subdivisions of the animal kingdom,
the _Mollusca_ and the _Articulata_, we advance to the Vertebrata,
animals distinguished from all those which have previously engaged
our attention, by the possession of a bony, jointed, hollow column of
support, or spine, formed of bones termed _vertebræ_ (_turn or whirl
bones_), and enclosing and protecting those strands or cords of the
nervous system called the spinal marrow; the former classes, being
destitute of such a structure, have the general name of _Invertebrata_.
In the beings whose mineralized remains form the subject of our present
investigation, the durable parts of the frame-work, or skeleton, are,
in most instances, situated internally, and their fossil relics consist
principally of the bones, or solid earthy portions of their structures,
either imbedded in the rocks in their natural relative position, or in
a state of dismemberment and dispersion. In most cases the teeth, and
in many the durable parts of their external integument, or skin, are
also preserved, in a greater or less degree of integrity.
In the lowest class of _vertebrata_, the Fishes, the skin is covered
with numerous pieces or scales, of a dense, durable substance, and
strengthened, in some families, by the addition of osseous plates; thus
constituting a flexible and almost impenetrable coat of armour, which
affords suitable protection to beings peculiarly exposed to external
injuries, from the nature of the regions they inhabit, and the state
of warfare with each other in which they are constantly engaged.
Confined to a fluid medium, they are provided with organs fitted for
aquatic respiration, called _branchiæ_, or gills, and with instruments
of progressive motion, termed _fins_, by which they are enabled to
propel themselves through the water with great velocity. The apparatus
for seizing, tearing, and crushing their prey presents numerous and
important modifications, corresponding to the habits and economy of the
different genera; their teeth offering as great variety of form and
structure as those of the higher orders of animals.
The cartilaginous or the osseous nature of the skeleton, and the
number and position of the fins, were the characters formerly employed
in the classification of Fishes; but Prof. Agassiz, conceiving the
structure of the skin to afford a natural index to the essential
modifications of organization and functions, has, with great sagacity,
adopted an arrangement founded upon the form and structure of the
scales; and he has divided the whole class into four orders, each
distinguished by essential differences in the dermal (skin) system.
To the geologist this method has proved of inestimable value; for it
is simple, easy of application, and, so far as our present knowledge
extends, may be relied upon as affording accurate conclusions as to
the nature and relations of the originals to which a few detached
fossil scales may have belonged. Another important aid has been derived
from the microscopical examination of the structure of the teeth; and
a splendid work on this subject by Professor Owen has opened a wide
field of palæontological investigation, which is yet but very partially
explored.[505]
[505] Odontography; or, a Treatise on the Comparative Anatomy of
the Teeth; their Physiological Relations, Mode of Development, and
Microscopic Structure; illustrated by upwards of 150 plates. By Prof.
R. Owen, F.R.S. &c. 4to. London. 1840-1845.
The living species of Fishes exceed eight thousand; and those found
in a fossil state, and determined by M. Agassiz, already amount to
upwards of one thousand five hundred; while several hundreds are
still undescribed; and the rapid progress of geological research is
continually adding to the number: upwards of six hundred British fossil
species are enumerated. In an initiatory work like the present, it will
be necessary to confine our remarks to an illustration of the mode in
which the investigation of the fossil remains of the animals of this
class should be conducted; and, by the elucidation of a few leading
principles, prepare the student for the perusal of works expressly
devoted to this branch of Palæontology.[506]
[506] The admirable and important work entitled "_Recherches sur
les Poissons Fossiles, par Louis Agassiz_," stands preeminent in
this department of science. It consists of five volumes, 4to. of
letter-press, and five volumes, folio, of coloured plates. It must be
consulted by all who would acquire a correct view of the present state
of fossil Ichthyology. _It is from this work that the commentary in the
text has been chiefly derived._
The fossil remains of fishes rank in the first class of the "Medals
of Creation," for they demonstrate the existence of numerous tribes
of highly organized beings in some of the most ancient fossiliferous
strata, and the continuance of the same type of organization, variously
modified, through the entire series of subsequent deposits to the
present time. Each geological formation contains peculiar groups of
fossil fishes, distinguished by distinct modifications of structure.
Thus, according to the data at present obtained, all the osseous fishes
anterior to the Chalk belong to genera which have no representatives
among existing species; and they are characterised by rhomboidal scales
covered with enamel.
The state of conservation in which the fossils of this class occur,
appears to have depended on the relative delicacy or firmness of the
original structures, and on the nature of the deposits in which the
fishes were imbedded. Thus the fossil fishes of the early formations,
which are characterised by their dense integument and enamelled
scales, often present the entire forms of the originals, and generally
considerable portions of the connected scales, with the fins and other
appendages: while the specimens of later deposits, which contain
a large proportion of species with delicate scales, more often
display the mineralized osseous skeleton, than the dermal structure.
Sedimentary strata composed of mud or fine detritus, of whatever age,
have been most favourable to the preservation of the entire forms;
hence we often find in the pulverulent clays and marls of the Tertiary
strata, in the Chalk of England and Westphalia, and in the fine
lithographic stone of Solenhofen, fishes perfect in form, and not only
individuals, but groups, with the scales, fins, head, teeth, and even
the capsule of the eye, in their natural positions. A small slab of
marl from Aix, in Provence, in the collection of Sir R. I. Murchison,
contains scores of small fishes, as perfect as if recently imbedded
in soft mud: a portion of this specimen is represented, _Lign. 184_;
and the beautiful fish figured in the frontispiece of vol. i. (pl. i.
_fig._ 3), from near Castellamare, will serve to illustrate the state
of perfection of some of the ichthyolites of the Jura limestone. In
the Chalk, many of the fishes are uncompressed, the body being as
perfect in form as if the original had been surrounded by soft plaster
of Paris while floating in the water. But in coarse limestones and
conglomerates,--in other words, in materials that have been subjected
to the action of the waves and torrents,--detached teeth, scales,
bones, &c. constitute the principal vestiges of this class of beings.
In illustration of this department of Paleontology, it will be
expedient to consider,--1stly, the characters afforded by the scales
and dermal appendages; 2dly, the teeth, or dental organs; 3dly, the
osseous and cartilaginous skeletons; and lastly, apply the data thus
obtained to the elucidation of some of the principal fossil genera and
species.
Scales of Fishes.--The dermal plates or scales are composed of two
substances, disposed in laminæ or plates; the one cartilaginous or
horny,--the other dense and osseous, possessing the structure of bone.
In most species the scales are imbricated, _i. e._ lie over each other
like the tiles of a roof; the margin of a front row partly covering the
series immediately behind. From this arrangement, the apparent shape
of the scales is very different from their true form; the processes of
attachment and the lateral angles being concealed. The scales that are
not imbricated are either very small, and imbedded in the substance of
the skin so as to be imperceptible to the naked eye, as in the shagreen
of Sharks; or are disposed in the form of bosses or scutcheons, as in
the Rays; sometimes bristling equally over the surface of the body,
as in the _Diodon_; and sometimes covering it like mosaic work; or
forming particular series on certain regions of the body, while the
other parts are garnished with different scales, as in the Sturgeon.
There are a few genera destitute of scales. In almost all fishes there
is a particular series disposed in a gently undulated line along each
side of the body, from the head to the tail, and constituting what
is termed the lateral line; these scales are tubular, and serve an
important purpose in the economy of these animals. Every one must be
aware that the body in most living fishes is constantly covered with
a kind of mucus, or slime, which serves to lubricate the skin and to
defend it from the action of the surrounding medium. This fluid is
secreted by a mucous canal or duct, which extends along the body, and
ramifies in all the bones of the head, jaws, &c.; and it is distributed
over the surface of the head by numerous pores in the bones, and over
the body by the tubes formed by the row of scales above described.
[Illustration: Lign. 185. Fossil Scales of Fishes. (_highly magn._)
_Chalk._ _Lewes._]
Fig. 1.--Scale or plate of the _shagreen_ of a Shark.
2.--Scale of Macropoma Mantelli; the exposed surface.
3.--Scale of Beryx Lewesiensis; the exposed surface.
4.--Scale of Osmeroides Mantelli; the entire form.
The four orders into which this grand class of vertebrata is divided by
M. Agassiz, are founded upon the peculiar structure of the scales;[507]
and are characterised as follow:--
[507] For illustrations of the scales of fishes, see _Wond._ p. 339,
_Lign. 68_, and p. 340, _Lign. 69_; _Foss. Brit. Mus._ p. 419; and
_Ly._ fig. 306, figs. 342-347, &c. And for their minute structure, see
Prof. Williamson’s important paper in the _Phil. Trans._ for 1851.
_Order I._ Placoid (_a broad plate_).--The skin covered irregularly
with enamelled plates, sometimes of a large size, but frequently in
small points, as the shagreen on the dermal integument of the _Sharks_
and the tubercles of the _Rays_. _Lign. 185, fig. 1_, a fossil
_placoidian_ scale from the skin of a shark, highly magnified.
_Order II._ Ganoid (_splendid_, from the brilliant surface of the
enamel).--The scales are of an angular form, and composed of plates of
horn or bone, covered with a thick layer of enamel; their structure
is identical with that of the teeth. The _Sturgeon_ is an example of
this order. _Lign. 196, figs. 1, 2, 3, 4_, are fossil scales of a
_ganoidian_ fish.
_Order III._ Ctenoid (_toothed, or comb-like_).--The scales are formed
of plates, which are toothed or pectinated on their posterior margin
or edge, like a comb. As the plates are superimposed on each other, so
that the lowermost always extend beyond the uppermost, their numerous
sharp points or teeth render the scales very harsh to the touch. The
_Perch_ belongs to this order. _Lign. 185, fig. 3_, represents a
fossil _ctenoidian_ scale.
_Order IV._ Cycloid (_circular_).--The scales are composed of simple
laminæ, or plates of bone or horn, without enamel, and have smooth
borders; but their external surface is often ornamented with markings.
The scales of the lateral line consist of funnels placed one within
the other; the contracted part of which, applied against the disk of
the scale, forms the tube through which the mucus flows. To this order
belong the Mullet, Salmon, and Carp. _Lign. 185, fig. 4_, is the
scale of a fossil _cycloidian_ fish.
Fins of Fishes.--As the progression of fishes through the water is
principally effected by the action of the tail, they have no limbs
commonly so called. The instruments for balancing the body, and for
assisting progression, are the fins, which are composed of numerous
rays that support a membranous expansion; and the number and situation
of the fins present various modifications in the different orders and
genera.
The fins are named according to the situation they occupy; for example,
_pectoral_, those on each side of the chest, and which correspond
to the anterior extremities of other vertebrated animals; _dorsal_,
on the back; _ventral_, on the belly; _caudal_, on the tail. (See
outlines of Fish, _Ligns. 186, 187, 195_.) The rays are of two kinds;
1st, the _Spinous_ rays; these consist of a single osseous piece,
usually dense and pointed, sometimes flexible and elastic, and divided
longitudinally (_Ligns. 188, 196_); 2d, _Soft_ or _articulated_ rays,
which are composed of numerous small articulations or joints, and
divide into branches at their extremities. Many species of fishes have
four fins; others six; some but two; and in certain genera they are
altogether wanting. In a fossil state the fins are often beautifully
preserved; even the soft rays in many of the Tertiary marls and in the
Chalk, are found entire, and attached to the body in their natural
situation. The large, strong, spinous rays of the dorsal fins of the
cartilaginous fishes, as the _Sharks_ and _Rays_, are generally found
detached, or connected only with a few vertebræ; but they are so
abundant in some of the Secondary deposits (and in numerous instances
they are the only vestiges of extinct species and genera), that they
possess great geological interest; they are distinguished by the term
_Ichthyodorulites_ (_fossil fish-weapons_), under which head they will
hereafter be described (see _Lign. 188_). The first ray in the dorsal
fin of some fishes is protected in front by a double row of enamelled
scales, and these often occur in a fossil state (see _Lign. 196,
fig. 5_).
Teeth of Fishes.--Of all the durable parts of animals teeth occur
in the mineral kingdom, the teeth of fishes present by far the most
numerous, varied, and striking modifications of form, structure,
composition, mode of arrangement, and attachment; and yet these dental
organs, separately considered, do not in many instances, either in
their structure or mode of implantation, afford characters by which the
natural affinities of the original can be satisfactorily ascertained;
and without the aid of other parts of the skeleton it is often
impossible to determine, from external characters only, whether an
unknown form of tooth belonged to an animal of the class of Fishes or
of Reptiles. Although the modifications of form are almost innumerable,
they are referable to four principal types; namely, the conical, the
flattened, the prismatic, and the cylindrical.[508]
[508] The "Odontography" of Professor Owen should be consulted by
those who would thoroughly comprehend this interesting department of
science. See also the _Article_ Teeth, by Prof. Owen in the Cyclopædia
of Anatomy and Physiology.
The conical teeth are extremely variable in size and form; some are
slender, almost invisible points, distributed like the pile of velvet
(_villous-teeth_), or set like the hairs of a brush (_brush-teeth_);
some are long and slender, or barbed at the point; others are obtuse;
and many are long and striated at the base, and closely resemble the
teeth of certain reptiles. The depressed teeth are equally diversified;
some have the grinding surface smooth; others, deeply grooved; in some
it is flat; in others convex. In form they are either lozenge-shaped,
elliptical, square, oblong, semilunar, &c. The cylindrical teeth are
hemispherical, or flattened; in some fishes they are short and thick;
in others slender and support an obtuse, conical crown. The prismatic
form is equally modified; from the compressed, sharp, lanceolate,
cutting teeth, to the strong, triangular, three-pointed dentary
organs.[509]
[509] For illustrations of the teeth of fishes, see plate iv. figs. 1,
2, 8, 10, and _Ligns._ 189, 191-194, 197, 198, 202, 205; _Foss. Brit.
Mus._ p. 449; and _Ly._ figs. 236, 308, 324, and 383.
The mode of arrangement and attachment of the teeth, is as diversified
as their forms. In some species all the teeth are of one type, and
disposed in somewhat of a serial order on both sides of the jaws; but
in a large proportion of fishes there are several kinds of teeth, which
are implanted not only in the jaws, properly so called, but on the
bones which form the cavity of the mouth, the arches of the palate,
tongue, &c.; and it is peculiar to this class of vertebrata to present
examples of teeth developed in the median line (_along the middle_) of
the mouth, as in certain species of Rays; or crossing the symphysis
(the _front line of union_ of the two sides) of the lower jaw, as in
_Myliobates_[510] (see _Lign. 194, fig. 2_). In some species the
teeth are implanted in sockets, to which they are attached only by the
soft parts, as in the rostral teeth of the _Saw-fish_; some have hollow
bases, supported upon bony prominences, which rise from the base of
the socket; as in several fossil teeth from the Chalk. "But by far the
most common mode of attachment is by a continuous ossification between
the dental pulp and the jaw,"[511] the teeth being thus anchylosed to
the bone. In the Sharks the osseous bases of the teeth are attached by
a ligamentous substance to the tough, dense crust, which covers the
cartilaginous jaws; the teeth of these fishes are therefore generally
found detached in a fossil state, in consequence of the decomposition
of this substance.
[510] Odontography, p. 5.
[511] Op. cit. p. 6.
The teeth are composed of a dense, osseous material, of a finely
tubular structure, termed _dentine_; which, in many species, forms on
the external surface of the tooth a layer of firmer texture, with a
glossy surface, resembling enamel. The essential character of their
organization is to have a pulp or medullary cavity, or cavities, filled
with a plexus of blood-vessels and nerves, from which the minute
tubes composing the dentine radiate.[512] The differences observable
in the size, mode of ramification, and distribution of the medullary
cavities or canals, and the _calcigerous tubes_,[513] as revealed by
microscopic exploration, constitute important distinctive characters;
particularly in the examination of the fossil teeth of extinct fishes.
In some teeth the dentine is traversed by equidistant, parallel,
medullary canals; in others, these channels frequently subdivide, and
their branches anastomose with each other. In some the medullary canals
form a reticulated, or net-like structure in the dentine, the meshes
of which are occupied by calcigerous tubes, and cells; often producing
a dendritical appearance, as in the tooth of a fossil fish named
_Dendrodus_. "In the highest type of structure, the dentine consists of
a simple medullary cavity or canal, and a single system of calcigerous
tubes, which radiate from the central or sub-central pulp-cavity, at
right angles to the periphery of the tooth" (_Owen_), as in the teeth of
the extinct Sauroid (_lizard-like_) fishes. A continued succession of
teeth takes place during the life of the fish, and we often find in
fossil specimens a series of successional teeth beneath the row in use;
as in the fragment of a jaw of _Lepidotus_, from Tilgate Forest _Lign.
107_.
[512] See Owen’s Odontography; and Tome’s Dental Physiology.
[513] _Calagerous tubes_; so named because they are composed of _calx_,
or lime.
Skeletons of Fishes.--The skeletons of the animals of this class differ
so remarkably in their relative degree of firmness and elasticity, in
consequence of peculiar modifications of their constituent substance,
as to form two grand divisions; one of which is termed the _osseous_, the
other the _cartilaginous_. The essential difference in the skeletons of
these two groups consists in the presence or absence of earthy matter
(_phosphate and carbonate of lime_) in the materials of which they are
constructed. In the cartilaginous fishes, the skeleton is cartilaginous
and transparent; but in some species, the skin has dense osseous
particles or plates on the skin, as in the _Rays_; and in others, the
head and body are protected by large osseous scutcheons, as in the
_Sturgeon_. There is also an intermediate group of fishes, termed the
_fibro-cartilaginous_, in which the skeleton contains lime, but in a
much less proportion than in the true osseous fishes. In some genera,
certain portions of the skeleton, as the bodies of the vertebra, are
cartilaginous, while the spinous processes, ribs, &c. are osseous;
these characters are of considerable importance in the investigation of
the fossil remains of fishes, as we shall hereafter have occasion to
demonstrate.
The skeleton consists of the _cranium_ or skull, which is composed
of numerous bones,--the jaws, and bones of the tongue,--the osseous
frame-work of the organs of respiration, consisting of the bones, rays,
and arches that support the gills, and the _opercula_, or covers which
close over the branchial apertures,--and of the vertebral column,
formed of numerous dorsal and caudal vertebræ, with the ribs and other
appendages; there are no proper cervical vertebræ, or spinal bones of
the neck.
The branchial arches are in general four or five on each side, and are
attached above to the cranium, and below to a chain of small bones, by
which they are connected with the _os hyoides_, or bone of the tongue.
The opercular bones, composing the cover or lid of the opening of the
gills, consist of three pieces on each side, and are distinguished by
the names, _opercular_, _pre-opercular_, and _sub-opercular_, according
to the situations which they respectively occupy.
The _vertebræ_ are double hollow cones,[514] not unlike an hour-glass
in form: the interval between two of these bones is filled up, in the
living state, by a gelatinous fluid. Along the upper part of each
vertebra, there is an annular cavity, which in the united vertebral
column forms a canal for the spinal marrow; the posterior dorsal and
caudal vertebæ have also a channel below, for the passage of the large
blood-vessels.
[514] There are certain exceptions; thus in the _Lepidosteus_ the
vertebral column is a series of ball-and-socket joints, the convexity
being anterior, as in the land Salamander, and in the fossil reptile
known as the Streptospondylus.
There are likewise bones analogous to some of those which enter into
the composition of the extremities, chest or thorax, and pelvis of
the higher vertebrata; but which it is not necessary for our present
purpose here to describe.
Of the organs of vision some fossil remains also occur. The sclerotic
coat, or capsule of the eye, being bony in fishes, is often preserved;
and in several chalk specimens I have found it occupying the orbit.
In addition to those durable parts of fishes, already mentioned, as
likely to be met with in a fossil state, the bones called _otolithes_
(ear-stones) must be enumerated. These calcareous bodies are found in
the membranous labyrinth of the organs of hearing; and, although more
or less developed in the ear-bulb of all animals, they are larger and
of more definite forms in the higher osseous and cartilaginous fishes.
The _otolithes_ are supposed to assist in communicating more vivid
impressions of sounds to the extremities of the auditory nerves; they
are stony in most aquatic animals, and friable or pulverulent in those
that live on land. Smooth, oblong otolithes are not uncommon in the
Crag deposits of Norfolk and Suffolk; and minute ear-bones are found in
the Barton Clay.
Tails of Fishes.--The tail, as we have previously mentioned, is the
chief instrument of progressive motion in these animals; it assumes two
principal modifications. In the greater number of the existing species
the vertebral column terminates in a triangular plate of bone (formed
by the fusion of the last few vertebræ), to which the caudal fin is
attached symmetrically; and its figure is either rounded, or divided
into two equal lobes or branches; these tails are termed _homocercal_,
i. e. even-tail. In the second modification the vertebral column
towards its extremity diverges from a straight line, rises up, and is
prolonged into the upper lobe of the tail; the caudal fin appearing
like a rudder, and its low’er lobe, being destitute of vertebræ, is
proportionably very feeble and small, as in the Shark and Dog-fish:
this form of tail is called _heterocercal_, i. e. unequal-tail (see
_Foss. Brit. Mus._ p. 421; and _Ly._ figs. 340, 341). In the embryonic
state the tail in all fishes is heterocercal, and it becomes homocercal
in the progress of development in those genera which have this type
of the caudal appendage. But few of the existing species have the
heterocercal tail, while it is found in all the fossil fishes that
occur in the ancient secondary strata; namely, the Magnesian limestone,
and antecedent deposits. The rounded and equal-bilobed, or homocercal,
tails, are seen in the fishes from the Chalk, _Wond._ pp. 347, &c.; and
in the Wealden Lepidotus, _Lign. 186_; and the unequal or heterocercal
tail is shown in the Amblypterus from the Carboniferous strata, _Lign.
187_.
[Illustration: Lign. 186. Lepidotus. _Wealden._ (1/6 _nat. size_.)
(Showing the Homocercal Tail.)]
[Illustration: Lign. 187. Amblypterus. _Carboniferous._ (1/4 _nat.
size_.)
_a._ The heterocercal tail.]
In the Annals of Nat. Hist, for 1848, p. 304, Prof. M’Coy has described
and figured an intermediate form of tail, which he regards as
characteristic of the _Diplopterus_ (of the Old Red Sandstone) and its
allies: this the Professor terms the _Diphycercal_ tail.
From this brief summary of the essential characters of those durable
parts of the organization of fishes, which most frequently occur in
a fossil state, we pass to the investigation of some illustrative
examples of this class of organic remains. But before describing any
entire specimens, it will be expedient to notice the separate fins,
and teeth, which abound in many deposits; in some instances occurring
in connexion with other parts of the skeleton, but more generally
detached, and constituting the only evidence of the existence of
numerous extinct species and genera. The greater part belong to
the first order--the Placoidians (_Poiss. Foss._ tom. iii.), and
to the families of _Sharks_ and _Rays_. The osseous dorsal rays of
cartilaginous fishes (named _Ichthyodorulites_ (_fossil-fish-weapons_)
by Dr. Buckland and Sir H. De la Beche) first demand our notice.
Ichthyodorulites. _Lign. 188._--This name is applied to the fossil
spines, or rays, of dorsal fins, of which numerous species occur in
the Secondary deposits; they belong, for the most part, to extinct
cartilaginous fishes of the _Cestracionidæ_ and _Hybodontidæ_ groups.
In the osseous tribes the dorsal spines have at their base two
articular processes, by which they are united to the osselets that
support them, as in the _Silurus_; but in the cartilaginous, they have
no articulations at the base, and terminate in an obtuse point, which
is implanted in the flesh; the posterior margin is grooved almost to
the upper extremity. They are of a fibrous, osseous texture. The common
Spinax, or Dog-fish (_Acanthias vulgaris_), has a spine of this kind in
the front of each dorsal fin. The rays of the Sharks are compressed,
and some have rows of teeth on the posterior margin; in the genus
_Cestracion_ (Port-Jackson Shark), these organs are strong, triangular,
straight, pointed, rounded in front, flat at the posterior face, and
widest at the base; in the Hays they are flattened or depressed.
These spines are generally capable of being elevated and depressed, and
not only serve the purpose of defence, but, in many instances, afford
support and protection to the soft rays of the fin; forming, as it
were, a moveable mast, by which the sail can be spread out or lowered
at pleasure.
In illustration of this subject, I would first direct attention to the
beautiful fossil, figured _Lign. 188, fig. 1_, which was discovered
in the Chalk near Lewes, and is figured, of the natural size, _Foss.
South D._ tab. xxxix. This ray, or spine, belongs to one of the
Cestraciont fishes (_Ptychodus_), whose teeth are so abundant in the
Chalk, and will presently be described. It is composed of fourteen
thick, flat, osseous rods, or strands, intimately united together, with
longitudinal furrows or sutures on the surface. The anterior margin is
embossed, and the projections form on the sides wide, rounded ribs, and
transverse depressions. Towards the base of the posterior part, there
are large osseous fibres inserted vertically and obliquely, which
appear to have been processes of attachment. The rods, or plates, are
parallel With the posterior margin, and each terminates in a rounded
extremity, or boss, on the front edge of the spine. This ray is wider
at its base than at the superior part the anterior margin is oblique,
and the posterior straight. The surface, where entire, is covered with
a dense osseous substance, which is finely engrailed.[515]
[515] This specimen is figured in _Poiss. Foss._; but it is represented
too short, from the two portions being drawn as if they were connected,
without any interval between them, as in _Lign. 188._ It is in the
British Museum. See _Petrifactions_, p. 450.
[Illustration: Lign. 188. Dorsal Rays of Sharks. _Sussex._]
Fig. 1.--Ptychodus spectabilis. 1/5 _nat._ _Chalk._ _Lewes._
1_a_.--Portion of a Dorsal Ray, with oblique serrated sutures.
_Chalk._ _Lewes._
2.--Ptychodus Gibberulus. 1/5 _nat._ _Chalk._ _Lewes._
3.--Hybodus subcarinatus. _nat._ _Weald._ _Tilgate Forest._
In 1850 I discovered in the Plastic Clay of Castle Hill Newhaven, a
dorsal fin of Ptychodus, with eight vertebræ. A nearly entire fin-ray
of this species, three feet in length, has recently been discovered by
Mr. Charles Potter, of Lewes, in the Chalk near that town. The remains
of another ray, of equal proportions, were found near it; and these
dorsal spines might have belonged to the same individual, for there are
no reasons to forbid the supposition that the Ptychodus had two dorsal
fin-rays. The length of these spines necessarily indicates a very large
fish.
A smaller species of Ichthyodorulite, also found in the Lewes Chalk, is
distinguished from _P. spectabilis_ by its osseous plates contracting
towards their extremities, and terminating more suddenly on the front
margin, producing gibbosities less acute and more distant than in _P.
spectabilis_; this species is named _P. gibberulus_: see _Lign. 188,
fig. 2_.[516]
[516] This fossil is figured of the natural size, Foss. South D. pl.
xl. _fig._ 3.
The bony plates of these fins are occasionally found lying in irregular
groups in the Chalk, as if the fin had partially decomposed and the
plates separated. In one example, the rays are split asunder by a
piece of bone, apparently a portion of a long pointed tooth, firmly
impacted between them; as if the fish had been seized by some enemy,
and had escaped, with the tooth of its adversary in its fin. Very fine
specimens have been found at Charing, Kent, by W. Harris, Esq. F.G.S.
In the fragment of an Ichthyodorulite from the Lewes Chalk, a
remarkable structure is displayed; the osseous plates are united
laterally by smooth, longitudinal lines, as in those above described;
but they are also traversed by numerous oblique, finely-serrated
sutures. _Lign. 188, fig. 1a_.
The Chalk contains rays of other species of _Ptychodus_, as well as of
some allied genera. Of these, the most remarkable are smooth, arched,
pointed spines, having a shallow posterior groove, with an enamelled
surface, marked with fine longitudinal striæ, and frequent, parallel,
oblique lines. These, according to Sir P. Egerton, belong to a true
_Cestracion_ (see p. 584): they were first figured and described by me
(_Foss. South D._ tab. xxxiii. _fig._ 5) as belonging to the _Acanthias
major_, and were subsequently assigned to the genus _Spinax_ by Prof.
Agassiz (_Poiss. Foss._ iii. p. 62).
It may be necessary to remark, that the fins first described have been
referred to the fishes which yielded the large grooved teeth so common
in the Chalk (see _Pl. VI fig. 2_) in consequence of their affinity
to existing species, which have similar fins and teeth; and from the
circumstance that the Sharks of the genus _Lamna_, whose teeth also
abound in the Chalk, have no dorsal rays of this kind; still the
proof of identity remains to be discovered. In one specimen only have
I observed indications of any other part of the skeleton; it is a
spine of _Acanthias major_, the base of which rests on several dorsal
vertebræ (_Foss. South D._ tab. xxxiii.).
Hybodus subcarinatus. _Lign. 188, fig. 3._--The fishes of another
extinct genus of Sharks, termed _Hybodus_, from the gibbous form of
the teeth, were also provided with dorsal spines, which may be readily
distinguished from the preceding. These Ichthyodorulites are generally
long, slightly arched, and terminate in a point at the extremity; the
base, which was implanted in the flesh, is deeply grooved, and much
prolonged, being sometimes equal to one-third of the entire length.
The surface is marked with strong longitudinal ridges, parallel with
the anterior margin which is rounded and laterally compressed. The
posterior edge, which is more or less flat, has, towards the base two
rows of sharp arched teeth, which gradually approach ’each other, and
blend into one line on the upper part of the ray There are numerous
species of this genus in the Oolite and Lias. I have found one species
in the Chalk and a few in the Wealden. The small Ray figured _Lign.
188 fig. 3_, is from Tilgate Forest, and displays the usual characters
of these fossils. From specimens discovered in the Lias, associated
with the teeth, it appears that the _Hybodus_ had two dorsal fins, each
furnished with rays, as in the recent Dog-fish.
The microscopic structure of these rays is stated by M. Agassiz to
resemble that of the teeth: in some there is a pulp cavity, which
occupies the centre of the spine, and is surrounded by dentine, in
which the calcigerous tubes radiate direct to the surface; the external
enamel is a layer of dentine, in which the medullary canals are wanting.
In the strata below the Lias there are numerous Ichthyodorulites, some
of a large size, belonging chiefly to the Cestracion family, and of
extinct species, not observed in more recent deposits. Thus there are
several species of dorsal rays (named Onchus, from their hooked form,)
that are wide at the base, and bent backwards, with the posterior
margin destitute of teeth, in the Carboniferous, Devonian, and Silurian
formations; also immense compressed spines, having small teeth on the
posterior margin, and the surface covered with longitudinal striæ,
and finely toothed, transversely; hence termed Ctenacanthus, or
pectinated-spine (_Murch. Sil. Syst._ p. 596).
The fossil spine, named Orthacanthus (_Poiss. Foss._ vol. iii. pl.
xlv.), and found in the Coal of Manchester, has been discovered in
connexion with the body of the fish to which it belonged in the
Carboniferous deposits of Ruppersdorf in Bohemia (_Geol. Journal_, vol.
v. part ii. p. 23).
Some Ichthyodorulites have the surface richly ornamented with stellular
tubercles, and are termed Asteracanthus, or starry-spine; there are
very large fin-rays of this kind in the Wealden, Purbeck, Oolites, and
Lias.[517]
[517] For particular information on Ichthyodorulites, consult _Poiss.
Foss._ tom. iii. chap. i. About seventy species are enumerated.
The Ichthyodorulites of the _Rays_ have no cavity like those of the
_Sharks_, and are of a depressed form, and more or less flattened; they
are armed with teeth along their exterior margins, and not on the
posterior edge, as in the latter family.
Fossil Teeth of Fishes.--From the durable nature and striking appearance
of many of the fossil teeth of fishes, and their prodigious numbers in
some deposits, they are familiar objects to the collector. By far the
largest proportion of the detached teeth belongs to various species
and genera of that most numerous, and widely distributed family of
voracious fishes, the Sharks. In the Tertiary strata teeth of this
kind occur of a very large size; in the Chalk many species abound,
particularly of the lanceolate and compressed forms, and of the rugous,
mammillated, palatal teeth, commonly termed _palates_. As we pass
to the more ancient formations, teeth of different forms prevail;
and those which approach the recent types are either very rare or
altogether absent. We will select some examples of the different genera
in illustration of this subject; the previous observations on the form
and structure of the recent teeth render but few introductory remarks
necessary.
Fossil Teeth of Sharks.--The fishes of the Shark and Ray families
belong to the _Placoid_ order; the scales in the former consist of
enamelled plates and tubercles, forming a _shagreen_ surface; and in
the dermal integument of the latter they appear as spines and bosses,
irregularly disposed.
Notwithstanding the diversity in appearance of the teeth of Sharks,
they all possess one essential character of structure, namely, a
base, or osseous root of variable form, which is implanted in the
integuments; and a crown, or external portion, which projects into the
mouth, is covered with enamel or compact dentine, and assumes numerous
modifications, by which the fossil genera are characterized. These
teeth are never imbedded in sockets, nor united to the dentary margins
of the jaws; they only adhere to the integuments of the mouth, and the
covering of the maxillæ; they possess, in most of the Sharks, great
mobility. They are generally disposed in rows; the anterior ones,
being first used, fall out, and are replaced by those on the inner
series. New teeth are also continually formed behind those in use, and
advance successively towards the anterior rows as the latter are shed,
and in their turn occupy the front rank. (See Cyclop. Anat. _Art._
Teeth.) An examination of the fossil and recent teeth of Sharks and
Rays proves that the prevailing existing generic types have but few, if
any, representatives in the fossils, except in those which belong to
the Tertiary and Cretaceous formations; while the genera that appear
isolated, as it were, in the present seas have numerous analogues in
the Secondary strata.
The fossil teeth of this family may be divided into two grand
divisions; namely, those which are more or less of a polygonal,
obtusely conical, or depressed form, having a tesselated arrangement in
the mouth; and those of a triangular, lanceolate shape, with cutting,
or serrated edges, disposed in a series of rows on the jaws. The teeth
of the first group (_Cestracionidæ_) have most analogy to those of the
living genus Cestracion (_Port-Jackson Shark_); the second (_Sgualidæ_)
to the Sharks, commonly so called.
The Cestracion is the only living representative of a family of
squaloid fishes of a peculiar type, whose remains occur in almost the
earliest fossiliferous deposits; it inhabits the seas of New Holland
and the southern coasts of China. The jaws of the Cestracion are
relatively very large, and are armed with numerous rows of teeth,
essentially of two kinds; those situated anteriorly, or towards the
front of the mouth, being adapted for seizing and retaining the food,
and the posterior ones for crushing and bruising. The prehensile teeth
are sharp, angular, and pointed: the others are obtuse, polygonal,
enamelled, and disposed in oblique rows along the margins and inner
surface of both jaws; there are sometimes sixty in each jaw (see
_Bd._ ii. pl. xxvii 11. _fig._ A). Fossil teeth of this type are
exceedingly numerous in the Chalk, Lias, &c. but are very seldom found
in juxtaposition; the decomposition of the cartilaginous integuments
in which they are imbedded, having, in most examples, occasioned their
displacement and dispersion; specimens, however, are occasionally
discovered, in which numerous teeth, of various sizes, are disposed in
mosaic, in their natural relative positions.
The extinct forms of this family (_Cestracionidæ_) are known almost
only by their teeth; and according to the shape, structure, and
sculpture of these organs, M. Agassiz has arranged them into several
genera. They occur in most of the fossiliferous deposits.
Cestracion canaliculatus.--The teeth of a fish belonging to the
existing genus have been discovered in the Chalk of Kent; they are
figured and described by Sir P. Egerton in the beautiful work by Mr.
Dixon.[518] This unique specimen consists of a group of thirteen
posterior molar and three or four detached prehensile anterior teeth,
imbedded in a block of chalk about two inches square. The chief
distinction from the teeth of the recent Cestracion is in the presence
of a large medullary canal which traverses the base of each tooth:
hence the specific name.
[518] Dixon’s Fossils of Sussex, &c. p. 365, tab. xxxii. _fig._ 8. From
the t examination of a specimen lately found at Lewes, Sir P. Egerton
has been led to assign to this species the spine formerly described as
_Spinax major_.
Acrodus (_ridge-tooth_) nobilis. _Lign. 189, fig. 4_, _Ly._ p. 275,
_fig._ 307.--In the Lias and Oolite, oblong enamelled teeth, having the
surface of the crown covered with fine radiating grooves and striæ,
are well known to collectors, in many parts of England, by the name of
_fossil leeches_, from a fancied resemblance to a contracted leech.
They belong to an extinct genus of Cestracionts, named _Acrodus_ by
M. Agassiz. The crown of the tooth is enamelled, and covered with
transverse grooves, which diverge from a longitudinal furrow; the
base is in the form of a parallelogram inclined on its inner side.
These teeth were inserted along the jaws in oblique series, their
longitudinal direction corresponding with that of the bones which
supported them; in their natural position, the extremity of a hinder
tooth was enclosed between the two next anterior teeth. A beautiful
group is figured _Bd._ ii. pl. xxvii^_e_.[519]
[519] The microscopical structure of the teeth of _Acrodus_ is well
shown in the "Odontography," pl. xiv. xv., and beautifully illustrates
the relation of dentine to bone.
[Illustration: Lign. 189. Fossil Teeth of Sharks.]
Fig. 1.--Ptychodus Mortoni. (G. A. M.) _Cret._ _New Jersey._
2.--Psammodus cinctus. (_Ag._) _Mt. L._ _Bristol._
3.--Orodus cinctus. (_Ag._) _Mt. L._ _Bristol._
4.--Acrodus nobilis. _Lias._ _Lyme Regis._
Ptychodus (_wrinkle-tooth_). _Pl. VI. fig. 2_; _Lign. 189_, and _Lign.
191_.--The palatal teeth, which occur more or less abundantly in almost
every chalk-pit, and are known by the name of "palates," belong to
several species of the genus Ptychodus. A very common form is figured
_Pl. VI. fig. 2_; and microscopic views of vertical and transverse
sections, as seen by transmitted light, are shown in figs. 2^_b_,
2^_c_. Groups of these teeth, somewhat naturally arranged, and varying
in size and form according to the situations they occupied in the
jaws, are occasionally found: one specimen in the British Museum, and
formerly in my collection, contains more than 120 teeth. In general
they occur in a very perfect state, with the osseous base and enamelled
crown entire. The dorsal rays or spines previously described (p. 577),
are sometimes found with the teeth, and belong to fishes of the same
genus.
These teeth are of an angular form, and more or less square, the crown
is wider than the root, which is obtuse, truncated, and depressed in
the centre; the enamelled part of the tooth is expanded at the edges,
and forms in the centre a flattened or slightly convex mammillary
projection, which is traversed by large, acute, transverse, parallel
ridges. The borders are granulated, and the sides of the projection
marked with deep vertical plicæ or folds; this description particularly
applies to the species named _P. polygurus_, figured in _Plate VI._ Dr.
Buckland has represented a fine group of these teeth, _Bd._ ii. pl.
xxvi′. Another common species (_P. decurrens_) is distinguished from
the former by the connexion between the large furrows on the crown and
the granulations on the expanded border, which diverge from the outer
edge of the large folds to the margin of the enamel.
The microscopic structure of these teeth presents the same congeries of
medullary and calcigerous tubes as those of the recent Cestracion: see
_Plate VI. figs. 2^b, 2^c_.
The teeth of a species of Ptychodus occur in the arenaceous strata
of the Chalk-formation in New Jersey, which possess the essential
characters of the European types, but differ from them in their
configuration; the only specimen I have seen is figured _Lign. 189,
fig. 1_; it was presented to me by Dr. Morton. The enamelled crown
forms a conical projection, traversed by large inosculating ridges,
which radiate from the summit towards the margin.[520]
[520] I have named it _P. Mortoni_, in honour of my distinguished
friend, the eminent American naturalist and physician, Dr. George
Morton, of Philadelphia, by whom it was discovered.
Psammodus[521] (_sandy-tooth_). _Pl. VI. fig. 1_; _Lign. 128, fig.
2_.--To this genus are referred the fossil teeth of the extinct
Cestracionts, which have the crown formed of small vertical tubes,
with the grinding surface more or less smooth, and presenting only a
punctated or sandy appearance.[522] These teeth are generally flat or
slightly convex, and of a square or oblong form; the base is osseous,
and as large as the crown. Two species are figured, _Lign. 189, fig.
2_, and _Pl. VI. fig. 1^a_. A magnified vertical section of the crown,
displaying the medullary canals and radiating calcigerous tubes, is
represented _Pl. VI. fig. 1^b_, and a transverse section, _fig. 1^c_;
they are thin slices of a tooth, _P. porosus_, from the Black Rock
(Mountain Limestone), near Clifton, viewed by transmitted light. The
large, flat, quadrilateral, oblong teeth that abound in the Stonesfield
Slate belong to the _Strophodus magnus_.
[521] See Odontography, pl. xviii. xix.
[522] Ibid. vol. i. p. 59.
There are several kinds of fossil teeth which possess the same
essential structure as those of Psammodus, but differ in their
external characters; these are referred to other genera by M. Agassiz.
Thus Orodus, _Lign. 189, fig. 3_, comprises those elongated teeth
in which the centre of the crown forms an obtuse transverse cone,
traversed by a ridge from which oblique furrows diverge transversely
towards the circumference. Similar teeth, but with a smooth, obtusely
conical crown, are referred to the genus Helodus. Those with the
crown compressed and elevated, with a sharp edge, and with the base
surrounded by concentric folds, constitute the type of Chomatodes.
A similar crown, but subdivided by deep transverse ridges into
dentations, characterises the genus Ctenoptychius.
Ceratodus (_horn-tooth_) emarginatus. _Lign. 194, fig. 1._--Very
curious dental organs, possessing a structure analogous to that of
the teeth of Psammodus, are found in the Bone-bed of the Lias; they
consist of consolidated plates instead of separate teeth; there was
probably but one plate on each side the jaws. The upper margin is
generally undulated, and more or less worn by use. These dental plates
are composed of two distinct layers; the lowermost portion, or root, is
an osseous, reticulated tissue, as in cartilaginous fishes in general;
and the upper consists of dentine, with minute parallel vertical tubes,
as in Psammodus; these tubes are a continuation of the medullary tissue
of the osseous root.
One species occurs in the Great Oolite at Stonesfield, and very many
forms abound in the Bone-bed at Aust Cliff, near Westbury on Avon: and
in the Trias (bone-bed) of Germany the teeth of several species of
Ceratodus are very abundant.
The fishes to which these fossil teeth, referred to _Ceratodus_,
belonged were most probably Cestracionts; the ray-spine known as
_Nemacanthus_ is provisionally assigned to them.
Edaphodon. _Lign. 190_ and _Lign. 191_, _Ly._ p. 276, _fig._ 309.--The
Chimæroid fishes, though formerly placed with the Plagiostomes (Sharks
and Bays), constitute a distinct group, of which there are but two
recent genera, though several occur in a fossil state. Their dental
organs are very peculiar. Their mandibles are furnished with two
or more pairs of oblong teeth, composed of long hollow cylindrical
columns, placed nearly at right angles to the grinding surface, which
is pitted with minute depressions. These teeth are never shed, but are
persistent, and grow on through life, as in the Rodentia, exhibiting in
this respect a striking contrast with those of the Sharks, which are
feeble and numerous, and constantly replaced by rows of successional
teeth.
Fossil teeth of several species, some much larger than the recent,
have been found in the Tertiary, Cretaceous, and Oolitic deposits. The
first British specimen was discovered in the Chalk-marl at Hamsey, in
1820, by myself; but its nature was not suspected until more perfect
examples were obtained from the Kimmeridge Clay at Shotover by Sir
P. Egerton, and were submitted to Dr. Buckland, who subsequently
ascertained their characters and relations by an examination of
the dental organs of a recent _Chimæra_ in the Museum at Leyden in
1835.[523]
[523] Proceedings of the Geological Society of London, vol. ii. p. 209.
[Illustration: Lign. 190. Mandible of Edaphodon Mantelli.
_Chalk._ _Lewes._ (1/2 _nat. size_.)]
[Illustration: Lign. 191. Edaphodon leptognathus. 1/2 _nat._
_London Clay._ _Bracklesham._
The Upper and Lower Mandibles of the left side; viewed mesially or
from within.
Fig. 1.--The Upper Jaw; left ramus.
_p m._--The premaxillary bone.
1, 2, 3.--The three dental tubercles.
Fig. 2.--The Lower Jaw.
_s._--The symphysial surface, by which this ramus is united
to the opposite or right side of the jaw.
4, 5, 6.--The three dental tubercles, or triturating surfaces,
of the left ramus of the lower jaw.
]
Many specimens, both of the upper and lower mandibles, have since
been discovered in the Eocene beds, Chalk, Upper Greensand, Galt,
Kimmeridge Clay, and Stonesfield Slate. The subject has been carefully
investigated by Sir P. Egerton; and this eminent Ichthyologist has
tabulated the principal forms, and arranged them under five genera.[524]
[524] Viz. Ganodus, Ischyodus, Edaphodon, Elasmodus, and Psaliodus. See
Quart. Journ. Geol. Soc. vol. iii. p. 35; and Dixon’s Foss. Sussex.
In some species the external vertical wall of the plate is formed of
hard dentine, resembling enamel; in others the dentine is disposed
in isolated ramifications, producing a dendritical appearance; the
modifications of this structure occasion the differences observable
in the dental plates of the various species. In some, compact dentine
with parallel canals constitutes the mass of the tooth; in others, the
squamous dentine with ramifying tubes prevails.
I have figured the right upper and lower mandibles of the type named
Edaphodon (_pavement-tooth_), in which there are _three_ teeth or
dental tubercles on each ramus of both jaws, _Lign. 191_: the lower
mandible is produced anteriorly into a falciform beak:[525] the
articulating surface of the symphysis (2 _s_) is broad at the base,
and contracts gradually forward until the margins meet at the apex. In
_Ischyodus_ the lower jaw is deeper, less produced in front, and the
margins of the symphysis are parallel until abruptly truncated at the
extremities: the upper jaw has _four_ tubercles on each side.
[525] Hence M. Agassiz proposed the name of _Psittacodon_
(parrot-tooth) for this genus of Chimæroids.
The upper jaw in Elasmodus has but three tubercles, as in Edaphodon,
but the dentine of which they are composed is confluent, being rolled
round like a scroll in the substance of the bone, one edge forming the
margin of the tooth, and the other being buried deep in its centre.
The dorsal fin-ray or spine of the Edaphodon is laterally compressed,
with the posterior margin grooved, and the edges armed with fine teeth:
I have a specimen of the spine, with a pair of inferior mandibles of
the same individual, imbedded in a block of chalk from Kent; by favour
of Mrs. Smith, of Tunbridge Wells.
[Illustration: Lign. 192. Fossil Teeth of Sharks.
Fig. 1.--Hybodus medius. _Lias._ _Lyme Regis._
2.--Hybodus raricostatus. _Lias._ _Bristol._
3.--Carcharodon productus. _Tert._ _Malta._
4.--Hemipristis serra (fragment). _Chalk._ _Ratisbon._
5.--Otodus Obliquus. _Tert._ _Sheppey._
]
Hybodus. _Lign. 192, figs. 1, 2._ (_Bd._ pl. xxvii^_d_.)--Intermediate
between the obtuse crushing teeth of the Sharks previously described,
and those sharp, angular, pointed, dental organs of the Squaloids,
are those of the fishes which M. Agassiz has arranged in a sub-family
or group termed _Hybodonts_; the teeth of which are characterised
by their transversely elongated form, and the series of subacute,
compressed, conical cusps or points, which compose the crown. The
median cone is the principal, the lateral points being shorter and
smaller, as in _Lign. 192, fig. 2_; in some species the difference
between the median and lateral cones is greater, in others less, as
in _fig. 1_. These cusps have a coating of dense enamel, which is
plicated longitudinally on both faces. The base, which almost equals
the crown in size, is composed of a coarse osseous substance. The
internal structure of the crown differs from that of the Cestracionts,
in having no principal pulp-cavity, and in being chiefly composed of
dendritical dentine, with reticulated medullary canals. The form and
organization of these teeth show them to have been instruments for
cutting and tearing food. The Hybodonts, as we have already stated (p.
581), possessed two spinous dorsal fins; in their habits and economy
they probably did not differ from the ordinary Sharks. Teeth and spines
of this genus are common in the Trias, Lias, Oolite, and Walden, and
occur in the Green Sand and Chalk. There are several species of teeth
and fins in the strata of Tilgate Forest (_Foss. Til. For._ pl. x.).
In general the teeth are found detached, but occasionally they occur
in their natural position, adhering to the mineralized cartilaginous
jaws (_Petrif. Lign. 97_); as in the beautiful fossil figured _Bd._
pl. xxvii.^_d_; and in the fine specimen of _H. basanus_, from the Isle
of Wight, figured in the _Geol. Soc. Journ._ vol. pl. iv. There are
several related genera, founded on the situation, form, and division of
the principal cusps of the teeth.
Sharks with Cutting Teeth.--The jaws of the common squaloid fishes, as
the Lamna (_Porbeagle_) and Carcharias (_Great White Shark_), are so
common in collections of natural history, as to render a description
unnecessary. The numerous vertical rows of angular, laterally
compressed, pointed teeth, with sharp or serrated edges--in some
species consisting of a simple trenchant cusp, in others with small
lateral teeth, or denticles, at the base, are characters with which all
are familiar. Fossil teeth of this form are extremely abundant in the
Tertiary and Cretaceous deposits; and are commonly in a beautiful state
of preservation. The genera of these fossil teeth are founded on the
solidity or hollow structure of the cusps, their possessing cutting or
serrated edges, and the presence or absence of lateral denticles. But
the last character cannot in every instance be relied upon, for some
recent Sharks have rows of teeth both with and without denticles.
Carcharodon productus. _Lign. 192, fig 3._--The genus Carcharias
comprises the large Sharks with cutting triangular teeth, crenated
(_notched_) on their margins, and having a broad base. In
_Carcharodon_, the teeth differ from those of Carcharias in being solid
in the centre, while in the latter they are hollow; but in both genera
the teeth exhibit the same reticulated structure of medullary and
calcigerous tubes. The _White Shark_ and other large species belong to
these genera; some of which are upwards of forty feet in length. But
even these colossal fishes must have been far surpassed in magnitude
by the extinct species of the Tertiary deposits, if the teeth afford
a scale of proportions; for some of the fossil teeth from Malta and
the United States are six inches long, and five wide at the base;[526]
being twice the size of the teeth in the largest living species. The
specimen figured in illustration, _Lign. 192, fig. 3_, is of a small
size.
[526] For instance, some of the Maryland specimens of _Carcharodon
megalodon_. See an admirable memoir on the Fossil Squalidæ of the
United States, by Dr. R. W. Gibbes, Journ. Acad. Nat. Science,
Philadelphia. At the meeting of the British Association in 1851, J.
S. Bowerbank, Esq. F.R.S. read some interesting observations on the
comparison of these large fossil fishes with the recent _Carcharias
glaucus_ of Australia. See also Owen, Cyclop. Anat. _Art._ Teeth.
Hemipristis serra. _Lign. 192, fig 4._--The fossil teeth of this genus
are distinguished by serrated edges, that do not extend to the summit,
which is a sharp angular point; as in the fossil represented.
[Illustration: Lign. 193. Fossil Teeth of Sharks. _Chalk._ _Lewes._
Fig. 1.--Corax pristodontus.
2.--Lamna crassidens.
3.--Notidanus microdon.
4.--Ptychodus polygurus; seen laterally.
5.--Ptychodus polygurus; viewed from above.
6.--Lamna elegans.
]
Lamna elegans. _Lign. 193, fig. 6._--The fishes of the genus _Lamna_
(to which the recent shark called the _Porbeagle_ belongs) have teeth
with smooth trenchant edges, and a small sharp denticle (_little
tooth_) on each side the base, as in the fossil, _Lign. 193, fig. 6_.
The specimen, _fig. 2_, although devoid of denticles, probably belongs
to the same genus, for reasons already explained. Several species
abound in the Chalk; and they are associated with teeth, which are
relatively wider and shorter, and have large compressed denticles; the
latter are arranged in a separate genus, named Otodus (_eared-tooth_),
by M. Agassiz. The specimen figured _Lign. 192, fig. 5_, represents
_O. obliquus_; another species, _Otodus appendiculatus_, is abundant
in the Sussex Chalk. The large, wide, triangular, smooth teeth, with
trenchant edges, and destitute of lateral denticles, so common in the
Chalk, are related to Lamna, and are comprised in the genus _Oxyrhina_
(_Poiss. Foss._ tom. v. tab. xxxiii.).
Notidanus microdon. _Lign. 193, fig. 3._--These teeth differ
remarkably from those of the other genera of Sharks. The crown of each
tooth is composed of a series of sharp angular enamelled points, the
first of which is the largest, and is notched on its anterior edge; the
base or root is osseous, flat, with a slight longitudinal depression
below the border of enamel. These teeth are comparatively rare in the
Chalk. One species has been found in the Oxford Clay; and several in
the Tertiary strata. Specimens occur in Hordwell Cliff.
Corax pristodontus. _Lign. 193, fig. 1._--The teeth of the fossil
_Corax_ chiefly differ from those of the recent genus _Galeus_, to
which the _Tope_, or Grey Shark, belongs, in being solid; they are of
a triangular form, with a deep concavity or notch on the posterior
margin, the base of which is prolonged and forms three or four angular
points: the anterior edge of the tooth is finely serrated. The root of
the tooth, as in _Notidanus_, is a broad osseous plate. There is much
diversity of form in the Chalk specimens, which are all of a small
size, as in _Lign. 193, fig. 1_. In Sussex they are more common in
the Chalk-marl than in the Chalk.
The only fossil teeth of the Shark family resembling those of the
tertiary Carchariodonts, that have been discovered in the strata below
the Chalk, are from the carboniferous deposits of Yorkshire and Armagh.
These teeth are compressed, triangular, crenated on the edges, with
large plaits or folds on the enamelled surface, towards the base of the
crown. M. Agassiz refers them to a new genus, viz. Carcharopsis, with
the specific name of _Prototypus_.
Fossil Vertebræ of Sharks.--As the cartilaginous nature of the
skeleton in this family renders it unfavourable to preservation in the
mineral kingdom, the durable parts already described, and those which
are ossified, are almost the only relics found in a fossil state.
The dermal integument is, however, sometimes preserved; and I had a
beautiful example of shagreen, composed of irregular minute hexagonal
scales, one of which is represented highly magnified, _Lign. 185,
fig. 1_.
In the _Galeus_ and _Carcharias_ the vertebræ are more ossified than
in many other genera of cartilaginous fishes, and fossil vertebræ of
these sharks often occur in the cretaceous and other strata. Groups of
vertebræ of a large size occasionally occur in the Sussex Chalk; they
are circular, biconcave, and very short; one specimen is four inches
in diameter, and one inch long; their concavities are consequently
shallow. These vertebra: are composed of two shallow conical disks,
which are united by their summits, at the axis, and are connected and
supported by numerous wedge-shaped plates, that radiate from the centre
to the periphery (see _Foss. South D._ pl. xxxiii. _fig._ 10). My
collection contained a connected series of forty small vertebræ from
the Chalk near Lewes, which probably belonged to the same species of
Shark as the dorsal spine named _Spinax major_ (_Poiss. Foss._ tom.
iii. pl. xl^_a_ _fig._ 6).
Squaloraia. In the Lias of Lyme Regis, that inexhaustible storehouse
of fossil treasures, a considerable portion of the skeleton of a very
remarkable fish, partaking of the characters of the Sharks and Rays,
was discovered by Miss Mary Aiming, and is now in the Museum of the
Bristol Institution.[527] In this fish the jaws are prolonged into a
beak, like the Pristis (_Saw-fish_). It has the head of a Shark, with
a long beak; vertebræ of the Rays; with pectoral and ventral fins,
almost equally developed; a tail armed with, a spine; and spinous
bosses, as in the true Rays.
[527] It is figured and described by Dr. Riley, Geol. Trans. 2d ser.
vol. v. pl. iv. See also Poiss. Foss. tom. iii. pl. xlii.
Fossil Pristis, or Saw-fish.--This well-known predatory fish, which is
allied to the Rays and Sharks, and referred by M. Agassiz to the family
of _Raiidæ_, has projecting from its snout an osseous, flat, horizontal
plate, or beak, equal in length to one-third of the fish, and armed on
each side by a row of elongated, compressed, pointed teeth, implanted
in sockets; the front margin of these teeth is convex, the posterior
concave; this defence is termed the saw, and constitutes a most
powerful weapon. The _Pristis_ has also numerous small obtuse teeth on
the jaws. The remains of the beak, or saw, of an extinct species of
Pristis have been discovered in the Bagshot Sand at Goldsworth Hill,
Surrey,[528] and three other species have been found in the London
clay of the Isle of Sheppey, and the Eocene beds at Bracklesham and
Hordwell.[529]
[528] Proc. Geol. Soc. vol. ii. p. 687.
[529] Two teeth are figured in Dixon’s Fossils of Sussex, pl. xii.; the
specimens are in the British Museum; see _Petrifactions_, p. 414.
Fossil Rays.--The teeth of these fishes are characterised by the
extraordinary transversal development of the median teeth in both
jaws. Instead of pointed teeth, they have wide, flat, tesselated
dentary plates in each jaw, composed of distinct pieces, juxtaposed and
connected by their margins, and united by fine sutures. In some species
the teeth are equal, in others of various sizes; they present numerous
modifications of arrangement, and are always disposed in symmetrical
rows. In the genus Myliobatis (_Eagle-ray_) the teeth of the median row
are of an extraordinary width, while their length does not exceed that
of the lateral plates, or chevrons, which are of an irregular hexagonal
form, and disposed in two or three rows on each side. There are five
living species of _Myliobatis_, and eighteen fossil species have been
found in the Tertiary strata at the Isle of Sheppey, Hordwell Cliff,
and Bracklesham Bay. I have figured a specimen of part of the upper
jaw of a species (_M. micropleurus_, _Lign. 194, fig. 2_), in which
the median teeth are very wide, and have two lateral rows of small,
irregularly hexagonal, plates. The surface of the teeth in this species
is smooth; but in others it is striated longitudinally (_Bd._ pl.
xxvi^_d_. _fig._ 14). In an allied genus, Ætobatis, from the Tertiary
beds at Bracklesham, the lower jaw projects beyond the upper, and in
each there is a row of flat, transverse teeth, _without_ lateral plates.
[Illustration: Lign. 194. Fossil Teeth of Fishes
Fig. 1.--Ceratodus emarginatus: 1/2 _nat._ _Lias Bone-bed._ _Aust Cliff._
A single dental plate.
2.--Myliobatis micropleurus: 1/3 _nat._ _Tert._ _Isle of Sheppey._
A series of six median teeth, with the corresponding lateral
teeth.
3.--Pycnodus Mantelli. _Weald._ _Tilgate Forest._ This specimen
consists of the _vomerine_ bone, with a median row of flat,
arched teeth, and two rows on each side of elliptical teeth,
arranged alternately.
]
To this notice of the fossil Rays, we may add, that a gigantic Torpedo
has been discovered in that celebrated locality of Ichthyolites, Monte
Bolca: and that Sir Philip Egerton has recently enriched his matchless
collection of fossil fishes, by a perfect Ray, from Mount Lebanon. It
is figured and described in the _Quarterly Geol. Journ._ vol. i. pl.
v. p. 225, under the name of Cyclobatis oligodactylus. It is a small
species, resembling the common Rays in its general appearance, but is
surrounded by a broad, flexible, cartilagino-membranous fin; the skin
is smooth, the teeth and eyes are small, the tail is slender; there are
no traces of dermal spines, tubercles, or defensive weapons. In many
points of structure it resembles the Torpedo; and may possibly, like
that fish, have possessed an electric organ. It is 3-1/2 inches long,
and 3 inches wide across the expanded fins.
CHAPTER XV.
FOSSIL ICHTHYOLOGY; COMPRISING THE GANOID, CTENOID, AND CYCLOID FISHES.
The fishes we have hitherto examined belong to the first order, the
_Placoidians_; we now pass to the fossil remains of the second order,
the _Ganoidians_, which are distinguished by their brilliant angular
scales, formed of osseous or horny plates, densely covered with enamel.
This order contains six or more families, comprising many genera and
numerous species; our investigation must be restricted to a selection
from the principal genera of the _Ganoids_, properly so called, and of
the _Sauroids_, or lizard-like fishes.[530]
[530] The fishes of these orders are described in _Poiss. Foss._ tom.
ii.
The first family, termed Lepidoides, contains several genera, which
are defined as possessing either numerous rows of brush-teeth, or
of obtuse conical teeth; flat, rhomboidal scales, arranged parallel
with the body; and an osseous, or partially osseous, skeleton. In one
division of this family, the body is either elongated or fusiform, the
mouth furnished with brash-teeth only, and the tail heterocercal, or
unequally bilobed (see p. 576). To this group belong several genera,
which are restricted to the Secondary formations more ancient than
the Oolite; while the other group, with homocercal tails, lived in
the Oolitic and Cretaceous seas. Two genera, in particular, abound
in the Permian and Carboniferous strata; namely, _Amblypterus_ and
_Palæoniscus_.[531]
[531] For the characters, affinities, and distribution of these and the
allied genera of the Heterocerque Ganoid fishes, see Sir P. Egerton’s
Memoir in the sixth volume of the Quarterly Geological Journal.
Amblypterus. _Lign. 187._ _Wond._ p. 740. _Bd._ pl. xxvii.^_b_.--The
fishes of this genus, as the name indicates, have very large and wide
fins, composed of numerous rays. The scales are rhomboidal and finely
enamelled; the tail is heterocercal. The figures referred to convey a
correct idea of the form and external characters. Beautiful pyritous
imprints of Amblypteri occur in the Carboniferous slate of Saarbrück,
in Lorraine; and fine specimens in the ironstone nodules of the same
locality. On the shore at Newhaven, near Leith, similar fossils occur
in nodules washed out of the cliffs of coal-shale (_Bd._ p. 278).
Palæoniscus. _Ly._ p. 304.--The fishes of this genus differ from
those of Amblypterus in the relatively moderate size of the scales,
and the numerous little rays on their margins. They have rhomboidal
scales, which in some species are very small, and in others large.
They have numerous brush-teeth. Several peculiar species, found in the
marl-slates and magnesian limestones of the Permian system, are very
widely distributed, occurring in the British Isles, Germany, and the
United States.
In some localities the small species occur in groups; on a slab of
red sandstone, in the Museum of the Geological Society, from Tyrone,
between two and three hundred perfect fishes (_P. catopterus_) are
imbedded on a space not exceeding two feet square.
A remarkable circumstance relating to the fishes of this genus is the
almost constant absence of the bodies of the vertebræ in otherwise
well-preserved specimens, and in which the spinal processes and the
ribs are entire: occasionally, however, examples occur with some of the
vertebræ perfect. An explanation of the above phenomenon may perhaps
be found in the probable originally cartilaginous nature of the bodies
of the vertebræ, and the osseous structure of the enduring apophyses
and ribs;[532] while those rare specimens which possess a few bony
vertebræ may be regarded as exceptions, in which ossification took
place in a structure essentially cartilaginous.
[532] Professor Owen states that a similar condition of the spinal
column obtains in the fossil Microdonts.--_Rep. Brit. Assoc._ 1846.
The fishes found in the copper-schists of the Zechstein, at Mansfeld in
Saxony, are generally impregnated with copper pyrites, and their scales
are as brilliant as burnished gold. These ichthyolites are almost
always in contorted and twisted positions; which appearance M. Agassiz
attributes to contraction of the muscular tissues after death, during
the progress of decomposition, and before the fishes sank down and
became imbedded in the mud. (_Poiss. Foss._ tom. ii. p. 70.)
The fishes of the genus Palæoniscus are often found in the shales and
marls of the Permian and Carboniferous systems of England and Scotland.
At East Thickley, in the county of Durham, numerous specimens have
been found.[533] The lower Carboniferous strata at Burdie-house, a
locality we have before mentioned, have yielded several species of
Palæoniscus, associated with teeth and other remains of large sauroid
fishes.[534] On the continent also they prevail in deposits of the same
epoch; Eisleben and Mansfeld, iii Saxony, are well-known localities.
In North America they have been discovered in strata of probably the
same age.[535] In fine, the genera Amblypterus and Palæoniscus may
be regarded as characteristic "medals" of the geological epoch which
intervened between the Devonian and Triassic formations.
[533] See Professor Sedgwick on the Magnesian Limestone. Geol. Trans.
2d ser. vol. iii.; and Prof. King’s Monograph on the Permian Fossils,
published by the Palæontographical Society.
[534] Dr. Hibbert’s Memoir on the Fossils of Burdie-house.
[535] Geology of Massachusetts, by Professor E. Hitchcock.
We will next examine a few genera of the homocercal Lepidoids and
Pycnodonts, whose relics are chiefly distributed in the Lias, Oolite,
Purbeck, and Wealden.
[Illustration: Lign. 195. Outline of the Dapedius. _Lias._ (1/2 _nat.
size_).]
Dapedius. _Lign. 195._--At Lyme Regis, and other productive localities
of the fossils of the Lias, large masses of angular enamelled scales,
and occasionally entire specimens of the fishes to which they
belonged, have for many years been collected. Sir H. De la Beche first
scientifically investigated the structure of these Ichthyolites, and
pointed out their characters and relations. The Dapedius (of which
a restored figure is given in _Lign. 195_) is a flat, laterally
compressed fish, with a rounded head, and fins of moderate size. The
body rapidly contracts towards the root of the tail, the fin of which
is large and symmetrically lobed. The mouth is furnished with several
rows of small conical teeth, which are crenated at their summits,
and has brush-teeth on the palatine bones; the jaws are short. The
scales are rhomboidal, highly polished, and united laterally by short
processes; as in many other ganoid fishes. It belongs to the Lepidoids.
The Tetragonolepis is a Liassic fish, very similar in shape to the
Dapedius. It was formerly grouped with the _Lepidoidei_, but Sir P.
Egerton has lately discovered that it essentially differs from those
fishes in the character of its scales and teeth, and that it belongs to
the Pycnodonts.
Lepidotus.[536] _Lign. 186, 196, 197._--Scales of a dark-brown, almost
black colour, with a glossy enamelled surface, and of a rhomboidal
or lozenge form, and teeth equally dark and glossy, of an obtuse
hemispherical figure, are very common in the Wealden strata of the
south-east of England and in the Isle of Purbeck. They are called by
the quarry-men _fishes' scales_ and _eyes_. The collectors of the
last century used to term the obtuse circular teeth of this and the
related genera _Bufonites_, from a supposition that they were formed
in the heads of toads. These relics belong to an extinct genus named
_Lepidotus_, which contains numerous species, that are distributed in
the Oolite, Purbeck, and Wealden formations. These fishes resembled the
Carps in their general form, but they have no anatomical relations to
that family. The body is covered with large rhomboidal scales, which
are protected on the external surface by a thick plate of enamel (Lign
196, _fig._ 3). The lateral line, which is slightly arched, passes
direct from the operculum to the middle of the insertion of the caudal
fin. The head, and even the face, are cased with osseous and enamelled
plates. The bones of the surface of the skull are very large, and are
connected by sinuous sutures. The jaws are short and rounded, and
furnished with a row of obtuse, conical, circular teeth (see _Lign.
197_), and several rows of sessile teeth, more or less contracted at
the base, which forms a very short pedicle that is anchylosed to the
bone. The fossil Lepidoti are found, for the most part, in fluviatile
deposits, as in the Purbeck and Wealden strata; and it is probable they
inhabited the rivers or sea-coasts, and not deep waters.
[536] _Poiss. Foss._ tom. ii. p. 233.
[Illustration: Lign. 196. Scales and Fin of Lepidotus Mantelli.
_Wealden._
_Tilgate Forest._ (_Nat. size._)]
Fig. 1.--Scale, with a single process of attachment.
2.--One of the scales of the dorsal line.
3.--Scale (external surface), with a bifurcating process of
attachment; the enamelled portion (which alone is visible when
the scales are in their natural position on the animal) has
longitudinal grooves or folds.
4.--Scale (viewed on the inner surface), having a bifurcating
process of attachment and a tooth or projection on each side,
to connect the scale laterally with the adjoining scales.
5.--The front ray of the dorsal fin, covered with two rows of
enamelled scales, and another ray behind it.
The scales and teeth figured _Lign. 196, 197_, belong to the larger
species of the Wealden. The remains of this fish were first collected
in Tilgate Forest, and several teeth and: scales are figured _Foss.
Til. For._ pl. v. and x.; considerable portions of connected scales
have since been found; also the head entire, and the fins more or less
perfect. A specimen in my collection retained a mass of the scales near
the insertion of the tail, a foot wide; indicating the original to
have been twelve feet long, and its body three feet broad. The scales
are distinguished from other species by the folds or grooves on their
enamelled surface; and the teeth by the contracted base, or pedicle,
which is a little narrower than the crown (_Lign. 197_, and _Pl. VI.
fig. 10_). A species (_L. Fittoni_) closely related to the above is
equally abundant in the Weald of Sussex; the scales are not striated,
and the teeth have no pedicle.
[Illustration: Lign. 197. Portion of the Jaw of Lepidotus. _Wealden._
_Tilgate Forest._ (_Nat. size._)
This specimen shows three successional teeth beneath a row of teeth in
use.]
The intimate structure of the teeth of the Lepidotus is beautifully
preserved, and may be easily examined in thin transverse and vertical
sections, viewed by transmitted light: see _Pl. VI. fig. 10_. The
dentine is composed of bundles of tubes, continued from the cells of
the osseous base, radiating in a vertical direction to the surface of
the tooth, as seen in _Pl. VI. fig. 10_, and giving off branches at an
acute angle; but when more highly magnified, the finer branches are
seen to be spread out and arched at their extremities, "presenting the
appearance of the stems of corn, beaten down by heavy rain."[537]
[537] Odontography, p. 70. See the beautiful representation of this
structure, pl. xxxi.
The dorsal and pectoral fins of these fishes are very strong, and
consist of several bony rays. There is a double row of acuminated
enamelled scales, arranged more or less obliquely, on the anterior
margin of the dorsal and anal fins, and on both margins of the caudal:
part of the first ray of a dorsal fin, with scales, is represented
_Lign. 196, fig. 5_.
A small species of Lepidotus (_A. minor_) is common in the Purbeck
limestone, and specimens may often be procured from the quarries near
Swanage;[538] it has also been found at Hildesheim, in Saxony, by M.
Roemer. The detached scales abound in the limestones; and the splendid
fossil reptile from Swanage, figured _Petrif. Lign. 38_, is sprinkled
with the scales and minute teeth of this fish.
[538] Fine specimens of this fish are in the British Museum
(_Petrifactions_, p. 429), and in the Museum at Dorchester.
The majority of the species of Lepidotus belong to the Lower Oolites
and the Lias. The habits of the Lepidoti, as indicated by the form and
structure of the teeth, were those of fishes whose food consisted of
crustaceans, shelly mollusca, &c.; for the dental organs are peculiarly
adapted for the crushing and grinding of such substances; and the teeth
of the adult fishes are generally worn down by use.
Pycnodus. _Pl. I. fig. 3_; _Lign. 194, fig. 3._--The fishes of
the family of Pycnodonts, so named from the thickness of their teeth,
have an osseous skeleton, a flat body covered with rhomboidal scales,
and flat or rounded teeth disposed in several rows on the palatine,
vomerine, intermaxillary, and premandibular bones.[539] As in the
Lepidotus, these teeth are constructed for crushing, and have generally
a smooth, dense, convex or flattened crown, with a highly polished
surface. This genus belongs chiefly to the Oolite; it is found also
in the Lias, Chalk, and Wealden. A perfect fish of the genus Pycnodus
(_P. rhombus_), from the Jura limestone, at Torre d’Orlando, near
Castellamare, is figured in the frontispiece of the first volume of
this work; and a vomerine bone, with teeth, from Tilgate Forest, in
_Lign. 194, fig. 3_. In the last fossil there is a median row of
flat,, elongated, transversely arched, smooth, glossy teeth, with a
double alternate row of small sub-circular teeth on each side, attached
to the bone, which is imbedded in Tilgate grit. Specimens of this kind,
belonging to one or more species of Pycnodus, occur in the Wealden
of Sussex; they were among my earliest discoveries in Tilgate Forest
(_Foss. Til. For._ pl. xvii. figs. 26, 27). Examples are met; with in
which all the teeth are shed, and the bony plate of the vomer alone
remains.
[539] The intermaxillary, palatine, and vomerine bones compose the
vault or roof of the mouth; the vomer occupying the middle; the
intermaxillary the front; and the palatine bones the sides; the
premandibular bones belong to the lower border of the mouth.
Gyrodus. _Lign. 198._--In another genus of the Pycnodonts, termed
Gyrodus, the crowns of the teeth are deeply furrowed, the structure
of the dentine is very dense, and the pulp-cavity large and simple.
One species occurs in the Speeton clay of Yorkshire, and another in
the Sussex weald; but the teeth are chiefly found in the Oolite and
Chalk. As in Pycnodus, the teeth are distributed in rows on the bones
composing the roof, floor, and sides of the mouth.[540]
[540] An extraordinarily perfect lower jaw of a Gyrodus is to be seen
in the British Museum (_Foss. Brit. Mus._ p. 439).
These characters are beautifully displayed in the Russian specimen,
_Lign. 198_. This interesting fossil was presented to me by the late
Stephen Cattley, jun. Esq., who collected it in 1839, in a valley near
Rjeff, a village on the banks of the Volga. Mr. Cattley informed me
"that many fossils are found in that and the neighbouring valleys;
and the locality is frequented by Russian geologists when the season
permits, which is but seldom, owing to the long duration of the snow,
and the heavy rains which accompany the thaw." This specimen consists
of the vomerine bone, which is of a coarse texture, and five rows of
teeth; the median row consists of very large elliptical teeth; those
of the lateral rows are much smaller and arranged alternately. The
peculiar structure of the teeth of this genus[541] is finely displayed
in this fossil. The ample, deep, and simple pulp-cavity is seen in
several teeth, where the crown of dentine has been worn off, filled
with a pure white calcareous spar; one of these cavities is marked a.
The dentine is extremely dense, consisting of very minute calcigerous
tubes, and passes into an external layer of enamel.
[541] Odontography, p. 72.
[Illustration: Lign. 198. Gyrodus Murchisoni[542] (G. A. M.) _Oolite?_
_Russia._
(_Collected by the late Stephen Cattley, jun. Esq._)]
Fig. 1.--The vomerine bone of a fish, with five rows of teeth; seen
from above; many of the crowns of the teeth are worn away
by use, and the large pulp-cavities, filled with white spar,
are exposed; as at _a_.
2.--Lateral view of the same.
_a._ One of the pulp-cavities filled with spar.
[542] It is with peculiar pleasure that I inscribe this new species of
_Gyrodus_ to Sir R. I. Murchison, in commemoration of those extended
and successful geological researches in the Russian empire, which have
conferred additional honour on his distinguished name.
The fishes of the genus _Gyrodus_ have the body large, flat, and
elevated; the dorsal and anal fins are very long; and the tail is
forked, with equal elongated lobes. The scales are laterally connected
by strong processes, as in Lepidotus.
Other genera related to the foregoing occur in the Oolite; as for
example, Microdon, thus named from the smallness of its very numerous
flat angular teeth, arranged in many rows; Placodus, in which the teeth
are few, flat, and of great size;[543] and Platysomus (_flat-body_),
with orbicular, clavate, teeth.
[543] Odontography, pl. xliii. _fig._ 1, and pl. xxx. _fig._ 2.
In these fishes, also, the dental organs are well adapted for the
comminution of shell-fish, and other hard bodies.
Cephalaspides of the Devonian System.--The remains of the three genera
of Ganoid fishes that we have now to notice are of a very remarkable
character, and are found exclusively in the Devonian or Old Red system;
most frequently in Scotland, but also in other parts of the British
Isles, and in Europe and America. These fishes agree in one general
character, that of having extensive osseous plates, or scutcheons;
their general aspect will be understood by reference to _Lign. 199,
200, 201_. There are no vestiges of the bodies of the vertebræ, which,
therefore, were probably cartilaginous. These fishes constitute a
distinct family with the name _Cephalaspides_, from the character of
the first genus we propose to describe.
[Illustration: Lign. 199. Cephalaspis Lyellii. (1/4 _nat. size_.)
_Devonian._ _Forfarshire._
Crushed specimen; seen from above.]
[Illustration: Lign. 200. Cephalaspis Lyellii. (1/4 _nat. size_.)
_Devonian._ _Glammis, Forfarshire._
Lateral view, showing the produced dorsal lobe of the tail.]
Cephalaspis Lyellii. _Lign. 199, 200._--The most striking feature in
the Ichthyolites of this genus is the enormous scutcheon, or buckler,
which forms the head, and is prolonged posteriorly into two lateral
horns or points; this part so closely resembles the cephalic shield of
certain trilobites (see _Lign. 175_), that the first found specimens
were supposed to be the remains of unknown crustaceans. The name
_Cephalaspis_ (_buckler-head_) is derived from this character. This
remarkable appearance is occasioned by the intimate anchylosis of
all the bones of the cranium. The body of these fishes is relatively
smaller than the head; it has one dorsal fin, and terminates in a
tapering tail, supporting a fin. There are two small eyes, placed
towards the middle of the head. The body is covered with rhomboidal
scales; and the head with discoidal scales, which are highly ornamented
with radiated markings[544] (_Ly._ p. 344, _fig._ 396). There are four
species of Cephalaspis at present known.
[544] Poiss. Foss. tom. ii. p. 135.
The other genera are equally unlike any recent types of the class of
fishes. No perfect examples have been found, and some parts of their
structure are still unknown; the annexed figures, _Lign. 201_, have
been drawn by Mr. Dinkel (the eminent artist employed by M. Agassiz),
with scrupulous accuracy, no part being introduced which is not clearly
demonstrated in some one specimen; and the form of the scutcheons is
made out very distinctly, to aid the collector in discriminating the
detached plates, which are the most common relics of these singular
beings.
Pterichthys cornutus.[545] _Lign. 201, fig.1._--This fish is
distinguished by its two wing-like lateral appendages; whence the name
of the genus (_winged-fish_). These processes, like the spines on the
gill-covers of the common Bullhead (_Cottus gobio_), are weapons of
defence. In some specimens they are extended at right angles to the
body (_Ly._ p. 345, _fig._ 400).
[545] The first fish of this genus was discovered by Mr. Hugh Miller,
in whose charming little work, "The Old Red Sandstone; or, New Walks
in an Old Field," will be found a very graphic description of the Old
Red fishes; I know not a more fascinating volume on any branch of
British geology. Consult also Sir P. Egerton’s elaborate paper on the
_Pterichthys_ in the Geol. Journal, vol. iv. p. 302.
The head and anterior part of the body are covered with large angular
tuberculated scutcheons. The under surface of the body is flat and
protected by five plates, a quadrangular plate occupying the centre.
The upper part of the body is convex; the form and disposition of the
dorsal scutcheons are shown in _Lign. 201, fig.1_. There are two
eyes, which are placed in front of the lateral spines: see _fig. 1._
The tail is of an angular form, and as long as the body; it is
covered with scales, and considered by M. Agassiz to have been the only
instrument of locomotion. The British species of this genus, of which
ten are known, are all very small, varying in length from one to ten
inches.
[Illustration: Lign. 201. Fossil Fishes of the Devonian System.
(_Drawn by Mr. Joseph Dinkel._)
Fig. 1.--Pterichthys cornutus, seen from above.
2.--Coccosteus oblongus.
These figures are restored with great care, from the best preserved
specimens hitherto discovered.]
Coccosteus oblongus. _Lign. 201, fig. 2._--The fishes of this
genus, as may be seen by the lignograph, very much resemble those
of Pterichthys; in both the osseous scutcheons of the body are very
similarly disposed. In _Coccosteus_, the head[546] is somewhat rounded;
slight rounded notches on the edge of the buckler indicate the place of
the eyes on the sides of the head. There is no indication of lateral
spines. The tail is very long, covered with scales, and supports a fin.
The plates of the body are tuberculated, as in Pterichthys. There are
six or eight teeth on each half of the lower jaw (and probably as many
on the upper), with a curious group of teeth situated on its symphisis.
The teeth are chiefly composed of bone, passing into dentine at their
surface.[547]
[546] This is of course only the cranial buckler of the animal, for,
as Mr. Hugh Miller observes, "of the true internal skull there
remains not a vestige. Like that of the Sturgeon, it must have been a
perishable cartilaginous box."--_Miller’s Foot-prints_, p. 50.
[547] Miller, Rep. Brit. Assoc. 1850. Transact. Sect. p. 92. In the
Annals of Natural History for November, 1848, Professor M‘Coy has given
a corrected outline of the carapace, or bony cephalo-thoracic casing,
of the Coccosteus. See also Miller’s Foot-prints, _fig._ 11.
These fishes are from a few inches to two feet in length; six species
have been discovered; and their remains are the most abundant of the
Ichthyolites of the Old Red. Patches of detached scales, and isolated
osseous plates, are very frequent in the sandy cornstones, and the
subcrystalline masses of limestone. These fragments are usually of a
brilliant blue or purple colour; and, strongly contrasting with the
dull red tint of the surrounding rock, are easily recognised. The
colour is supposed to be due to the presence of phosphate of iron,
which has communicated a similar tint to the Ichthyolites of the
Caithness Schist.[548]
[548] Murch. Sil. Syst. p. 588; see also a detailed description of
the Cephalaspis, Holoptychius, and other Devonian Ichthyolites, by M.
Agassiz, ibid. p. 589-601.
Fossil Sauroid Fishes. (_Poiss. Foss._ tom. ii.)--The family of Ganoid,
fishes termed _Sauroid_, or lizard-like, by M. Agassiz, are so named
in consequence of certain peculiarities in their organization which
are found in no other animals of this class, but exist in reptiles.
There are but two living genera; namely, the _Lepidosteus_, of which
there are many species that inhabit the rivers of America; and the
_Polypterus_, that contains two species, one inhabiting the Nile, and
the other the rivers of Senegal. In these fishes the bones of the
skull are closely connected by sutures; the teeth are large, conical,
and longitudinally striated, as in the crocodile, plesiosaurus, &c.;
the spinous processes are united to the bodies of the vertebræ by
suture, as in most reptiles; and the ribs are articulated to the
extremities of the transverse processes; the skeleton is osseous. Even
in the soft parts many analogies to reptilian structure are seen;
thus the Lepidosteus has a glottis, as in the _Siren_; and a cellular
air-bladder, with a tracheal vessel, resembling the lungs of an
Ophidian (_serpent_). These fishes are the only living representatives
of those voracious tribes of the most ancient marine fauna, whose
remains abound in the Secondary formations. Their relics have often
been mistaken for those of reptiles; particularly the teeth, which
from their large size, conical figure, enamelled and striated surface,
and internal cavity, were generally supposed to belong to crocodiles.
The scales are flat, rhomboidal, and parallel to the body. The recent
_Lepidosteus osseus_, of North America, affords a good illustration
of the fossil genera; a reduced figure of this fish, from _Poiss.
Foss._, will be found in _Bd._ pl. xxvii^_a_.; and teeth of some fossil
Sauroids are represented _Bd._ pl. xxvii.
The teeth of the Sauroids consist of two kinds; namely, large pointed
striated cones, and numerous small brush-teeth. The intricate structure
of the conical teeth of the _Stony-gar_, or Lepidosteus, is very
remarkable, and presents some analogy to that observable in the dental
organs of the Labyrinthodon, an extinct genus of reptiles, of which
we shall treat in a subsequent chapter. The tooth consists of a large
conical pulp-cavity, surrounded by a mass of dentine, which is plicated
longitudinally, its folds giving to the pulp-cavity an appearance of
being divided into parallel longitudinal branches; resembling, in
this respect, the base of the tooth of Ichthyosaurus, as shown in a
transverse section, _Pl. VI. fig 9_. If we imagine these folds to be
multiplied, and to have more inflections, and the pulp-cavity to be
reduced in its proportions, we shall have the elegant organization
of the teeth of the _Labyrinthodonts_ (see _Pl. VI. fig. 3^b_). The
dentine is composed of very minute calcigerous tubes, which pass off at
right angles from the pulp-cavity to the periphery; and it is covered
by a layer of cement, or coarser dentine, which is encased in a coat
of enamel, forming the external investment of the tooth.[549] The long
conical teeth are implanted in _alveoli_ or sockets, to the walls of
which they are anchylosed at their base.
[549] These remarks are based on M. Agassiz’s description and my own
observations. An interesting paper, "On the Microscopic Structure of
the Teeth of the _Lepidostei_, and their analogy with those of the
_Labyrinthodonts_, with a plate," by _Dr. Jeffries Wyman_, will be
found in Amer. Journ. of Science, October, 1843, p. 359.
Lepidostei.--This family, having the above described recent
_Lepidosteus_ for its type, comprises several genera, and is
represented in all the formations from the Tertiary to the
Coal-measures inclusive. The _Lepidosteus_ itself has left its remains
in the Eocene tertiary of England. The Lepidotus (before described,
p. 604,) ranges from the Chalk to the Lias; the _Pholidophorus_ and
_Dapedius_ (p. 603) abound in the Lias; the latter being found also
in the Wealden, and the former in the Oolite and Purbeck; and the
_Palæoniscus_ (see p. 601) is a well-known Permian and Carboniferous
form.
Sauroidei.--The remains of the Sauroids proper occur in the Chalk,
Purbeck, Oolite, Lias, Permian, and Carboniferous rocks. The great
strength and size of some of these teeth prove that the seas of
those remote periods were inhabited by voracious fishes of enormous
magnitude. See _Petrif._ pp. 432, _et seq._
The teeth and jaw of a gigantic sauroid (_Megalichthys_), from the
Carboniferous strata at Burdie-house, are figured _Bd._ pl. xxvii.; the
sections of the teeth shown in figs. 13, 14, of that plate, illustrate
the size of the pulp-cavity and the thickness of the layer of dentine.
These remains were associated with the plants and crustaceans
previously described; an assemblage of fossils indicating a lacustrine
or estuary formation. Similar teeth have been found in the cannel-coal
of Fifeshire.
In the Upper Lias of Ilminster, Somerset, the nodular calcareous rock
is rich with the remains of the _Pachycormus_, many fine specimens of
which Mr. C. Moore, of that town, has successfully worked out from
their stony encasement, exhibiting the gaping, contorted fish, as it
died in the convulsive throes of suffocation in the muddy sea. The
little sauroid _Leptolepis_, of the Lias and the Purbeck, is also
abundant in the above mentioned locality.
In the lithographic stone of Solenhofen, and in the Purbeck strata,
Oxford Clay, and Lias of England, occur specimens of a sauroid fish
remarkable for the extreme shortness of the lower jaw, and the
prolongation of the upper into a beak; it is named _Aspidorhynchus_ by
Agassiz. The figure of this fossil fish is contrasted on pl. xxvii^_a_.
_Bd._ with that of its recent ally, the _Lepidosteus_.
In the Shanklin sand and in the Galt of Kent and Sussex, large,
conical, striated teeth belonging to sauroid fishes are occasionally
found. They invariably occur detached, and no portion of the jaws has
been observed. In the Chalk of Sussex several fine sauroid fishes have
been discovered; such as the _Lophiostomus_,[550] _Belonostomus_,[551]
and _Caturus_; the last two of which are found in the Oolite and Lias
also. These have been described and figured in the late Mr. Dixon’s
"Geology and Fossils of Sussex."
[550] _Geol. Surv._ Dec. 6. pl. x. xi.
[551] _Petrif._ p. 431.
The Sauroidei-dipterini[552] are found almost exclusively in the
Devonian formation. _Osteolepis_, _Diplopterus_, and _Dipterus_ are
characteristic members of this family. Interesting descriptions and
instructive figures of the structure of these genera are given in
Mr. Hugh Miller’s late work, "Foot-prints of the Creator, or the
Asterolepis of Stromness," at pp. 50 to 61.
[552] The characters of the scales of this and the next family, as well
as of the Acanthodei, are succinctly given in Miller’s Foot-prints of
the Creator, pp. 30, _et seq._
Cœlacanthi.--This is a numerous family of sauroid fishes, that have
derived their name, _hollow-spine_, from the central cavity in the
fin-rays, which, however, may have had originally cartilaginous
cores. They are found from the Devonian to the Cretaceous series. In
the former, one of the most remarkable is the genus _Holoptychius_,
distinguished by the peculiar structure of the scales; the enamelled
surface of which is covered by undulated furrows. The whole body is
covered by thick enamelled scales of this kind. A splendid specimen,
twenty-eight inches long, and twelve wide, is figured _Murch. Sil.
Syst._ pl. ii.^{_bis._} Scales have been found exceeding three inches
in length, by two and a half in width; which must have belonged to a
fish of great magnitude. _Ly._ fig. 395.
In the Old Red Sandstone of Elgin, at a quarry at Scat-craig, some
peculiar teeth occur, which possess a very remarkable structure, and
have been referred to a genus of sauroid fishes, which, from the
dendritical or arborescent disposition of the calcigerous tubes,
Prof. Owen has named _Dendrodus_. These teeth are of a conical form,
slightly curved, and solid throughout. On the external surface they
are finely striated longitudinally, and have two opposite vertical
ridges; the base is rough, and its margin rounded, as if for attachment
to a shallow socket. The largest specimen is one and a half inch in
length. In thin sections, viewed microscopically by transmitted light,
there is a central pulp-cavity, of small size; the medullary canals
pass into a few short ramifications, like the branches of a shrub, and
these are distributed into irregular dilatations, simulating leaves,
which resolve themselves into radiating bundles of calcigerous tubes; a
portion of a transverse section[553] is shown _Pl. VI. fig. 8_.
[553] Odontography, pl. lxii. B _fig._ 2; and Cycl. Anat. _Art._ Teeth.
[Illustration: Lign. 202. Asterolepis. _Devonian._ (1/2 _nat. size_)
Inner side of portion of the lower jaw.
(After Miller.)]
[Sidenote: ASTEROLEPIS.]
In Mr. H. Miller’s charming work just referred to we have a full
and clear account of the singular fossil fish the Asterolepis.
Remains of this gigantic Ganoid were first found in Russia.[554]
Its name is derived from the stellate markings on the dermal plates
of the head, which are of great size, and form a strong expanded
buckler, the orbits of the eyes being situated near the anterior
border. (See Miller’s _Asterolepis_, pp. 74, _et seq._ figs. 27-29.)
_Lign. 202_ shows a part of the lower jaw of this fish, seen on the
inside. Along the upper margin are seen a "thickly set row of small
broadly-based teeth,"--these are ordinary _fish_-teeth; and behind this
edge-row of small teeth, _b_, there occur "a thinly set row of huge
_reptile_-teeth, based on an interior platform of bone, which formed
the top of the cartilage enclosing box composing the jaw." (Miller.)
These large teeth, _a a_, are longitudinally striated, and generally
bear two sharp lateral cutting edges.[555]
[554] Casts of the fossil bones from Russia are in the British Museum;
_Petrif._ p. 435.
[555] The microscopic structure of both kinds of teeth is elegantly
figured in Mr. Miller’s work, pp. 81, 82.
Macropoma Mantelli. _Wond._ p. 348. (_Foss. South D._ tab. xxxvii.
xxxviii.; _Petrif._ p. 436, _Lign._ 89.)--This Cœlacanth fish is
from one to two feet in length, of an elongated fusiform shape, with
a large head and two dorsal fins; the anterior fin is imbedded, and
has seven or eight strong spinous rays, the first two of which have
numerous spines. The opercula are very long and large (hence its
name); the scales[556] are garnished with adpressed spines, disposed
in semicircular rows (see _Lign. 185, fig. 2_). The teeth are small,
conical, and numerous.
[556] See Prof. Williamson’s Memoir, Philos. Trans. 1849, p. 435; pl.
xliii. figs. 27, 28.
Several specimens of this fish are almost perfect. The bones of the
cranium, the jaws, teeth, opercula, branchial rays, palatine arches,
the surface of the body covered with scales, all the fins, the pelvic
bones, the vertebræ and their apophyses, all remain.
In one example, the vomer, covered with minute teeth, is exposed.
But the most extraordinary fact relating to these Ichthyolites, is
the preservation, in every specimen, of the air-bladder;[557] even
its membranes remain, and separate in flakes; and the ramification
of the minute vessels is visible under a high magnifying power. In
some instances this bladder is displaced and much distended; but in
general it occupies its natural position, and retains its elongated,
sub-cylindrical form, with a few annular constrictions or folds.
[557] See Williamson, _op. cit._ pp. 462-165, and figs. 29, 30.
[Sidenote: COPROLITES. COLOLITES.]
Coprolites. _Lign. 139, figs. 1, 2._--In more than one example
the solid earthy residue of digestion, in small lumps or pellets,
of a conical form and spirally convoluted, lies in the abdomen of
these fossil fishes. Fossil excrementitious substances of this kind
are termed _Coprolites_ (_Bd._ p. 198, pl. xv.); they occur in many
deposits, and belong not only to fishes, but to large reptiles and
other animals. _Lign. 139_, p. 432, _fig. 1_, represents the coprolite
of a _Macropoma_; and _fig. 2_, that of a species of _Shark_, from
Hamsey. The convoluted appearance of these bodies arises from the
peculiar organization of the intestinal canal of the original fishes,
in which, as in the recent Dog-fish, a portion of the intestine was
spirally twisted, the tube forming several gyrations; and the passage
of the calcareous substance through this constricted canal gave rise
to the structure observable in the coprolites. In the Macropoma the
gyrations appear to have been few; seldom more than five or six
turns being apparent. In the fossil Sharks the convolutions are more
numerous, ten or twelve occurring in the length of an inch. In many
of the coprolites, the impression of the mucous or lining membrane of
the intestinal canal may be detected. Some of the coprolites of the
Macropoma are not convoluted; probably from having occupied the upper
part of the digestive tube, and therefore not having been moulded in
the spiral part. (See _Geol. S. E._ p. 145. _Foss. South D._ tab. ix.)
Minute scales and bones of fishes are occasionally imbedded in the
substance of the coprolites, affording evidence of the carnivorous
habits of the Macropoma.
Cololites. _Bd._ pl. xv^_a_--It will be convenient to notice in this
place those curious fossils which occur in detached masses in the
limestone of Solenhofen, and used to be known to collectors by the
term _lumbricaria_, from the supposition that they were petrified
earth-worms. An excellent representation of a fine specimen is given
by Dr. Buckland in the plate referred to above. These convoluted
bodies M. Agassiz, with his wonted sagacity, has ascertained to be
the intestines of fishes; and has therefore named them _Cololites_.
Although generally found isolated, specimens occur in which they are
imbedded, like the coprolites of the Macropoma, in the abdominal
region of fishes. The frequent occurrence of the _Cololites_ apart
from the body, is explained by the usual process of decomposition in
fishes. M. Agassiz remarks that dead fish always float on the surface
of the water with the belly uppermost, until the abdomen bursts from
distention. The small intestines are then expelled by the evolved gases
through the aperture, and soon become detached from the body. I have
observed indistinct traces of similar remains in the beds of chalk in
which fossil fishes most prevail. Dr. Buckland mentions the discovery,
by Lord Greenock, of a mass of petrified intestines distended with
coprolite, and surrounded by the scales of a fish, in a block of
coal-shale from the neighbourhood of Edinburgh (_Bd._ p. 199).
Dercetis elongatus. _Wond._ p. 349.--Before proceeding to the
investigation of examples of the next order, I will describe a highly
interesting Ichthyolite, which in a mutilated state is extremely
common in some of the chalk strata of the South-east of England; it is
noticed in _Foss. South D._ p. 232. This fish is placed by M. Agassiz
in his family of ganoidians, termed _Scleroderms_; and he mentions
that another species has been found in the chalk of Westphalia. The
_Dercetis_ has a very elongated body, with a short head terminating in
a pointed beak; the upper jaw is a little longer than the lower, and
both jaws are armed with long, conical, elevated teeth, and several
rows of very small ones. On each side of the fish there are three rows
of osseous scutcheons like those of the Sturgeon (see _Wond._ p. 349);
the body was also covered with numerous small scales. From the form
of the body somewhat resembling that of the eel, being very long, and
sub-cylindrical in uncompressed examples, the specimens are generally
called "_petrified eels_" by the quarry-men. The examples usually found
consist of the elongated body, more or less compressed, and irregularly
covered with patches of scales confusedly intermingled; among which
traces of the scutcheons may sometimes be distinguished. These
specimens occasionally exceed two feet in length, by one or two inches
in breadth; with neither extremity perfect, and without any vestige
of the fins.[558] The example figured _Wond._ _Lign. 74_, is the only
instance in which I have seen the cranium perfect. The scutcheons in
the Westphalian species have a prominent longitudinal ridge or keel,
and their surface finely granulated; they are so large that the whole
body of the fish is covered with them.
[558] See _Foss. South D._ pl. xl. _fig._ 2, and pl. xxxiv. figs. 10
and 11.
[Sidenote: CTENOID FISHES.]
Fossil Ctenoid Fishes (_Poiss. Foss._ tom. iv.).--The fishes of this
order have imbricated laminated scales, the posterior margins of
which are round and finely pectinated; _i. e._ divided into little
teeth, like a comb. These scales are nearly circular, but more or less
elongated; and, as the laminæ of which they are composed successively
diminish from the lowermost to the uppermost, the pectinated margin of
each being apparent, the surface is very scabrous; the front edge is
sinuous. The common Perch is the type of the Ctenoidians. The teeth of
these fishes are invariably small, and either villous or brush-like.
From the numerous fossil genera I select, in illustration of the
characters of this order, the _Beryx_; of which four species occur
in the English Chalk, and three others in the Chalk of Bohemia and
Westphalia. Of this genus, which is closely related to the Perch
(_Perca_), two living species inhabit the seas of Australia. The bones
of the skull have dentated crests; the dorsal fin has spinous rays in
front, which are united to the soft rays; the margin of the caudal fin
has little spinous rays.
The Beryx is one of the most ancient representatives of the Perch
tribe, and of the Ctenoid order.
Beryx Lewesiensis.[559] _Wond._ p. 351; _Petrif._ _Lign. 90._--This
is one of the most common of the Ichthyolites of the Chalk of the
South-east of England; it is called "_Johnny Dory_" by the quarry-men;
the specimens are from six to twelve inches long. It occurs also in the
Chalk of Westphalia. The outline of the perfect form of this species,
_Wond._ p. 351, by Mr. Dinkel, conveys an accurate idea of its external
characters. It has one dorsal fin, with several spinous rays in front
of the soft ray. The head is very large, and the opercular pieces are
ornamented with sculptured rays; the margins of the jaws are covered
with a broad band of brush-teeth. The orbit is large, and often
contains the capsule (_sclerotica_) of the eye. The rays of the gills
are short and thick, five are preserved in some examples. The scales
are very large; about twenty-five in the median row; their posterior
margins have several concentric rows of spines (see _Lign. 185, fig.
3_, p. 567). The lateral line is often distinctly apparent, in the form
of a tube, contracted behind and expanded in the centre of the scale.
The vertebral column is composed of large short vertebræ, with very
long apophyses; the ribs are slight.
[559] The fossil discovered by me, and figured in _Foss. South D._ tab.
xxxvi. was the first perfect fish obtained from the Chalk. This fish
was first described by me, _Foss. South D._ tab. xxxv. xxxvi. as Zeus
_Lewesiensis_; M. Agassiz has very properly referred it to the genus
_Beryx_; but he has also substituted another specific name; which is
wholly unwarrantable, for that first imposed ought to be retained; see
p. 518, note.
Beryx superbus.--This is a larger species, sometimes thirteen inches
long, with very large and broad scales. It has been found in the lower
chalk at Lewes. See Dixon’s _Foss. Sussex_, tab. xxxvi. _fig._ 5.
Beryx radians. _Wond._ p. 350.--This species is smaller, and relatively
longer, than _B. Lewesiensis_; it generally occurs in the Chalk-marl,
and is invariably of a very dark colour, the scales having a polished
or glossy aspect. The scales are small, with a simple row of diverging
spines on the posterior edge. The scales of the lateral line are
peculiar; the mucous canal is not formed of a series of simple tubular
cylinders, as in _B. Lewesiensis_, but is divided into several
branches, as may be seen with a lens of moderate power. There are more
than thirty scales in the length of the lateral line.
Beryx microcephalus (_Poiss. Foss._ tom. iv. tab. iv^_c_.; and Dixon,
_Foss. Sussex_, tab. xxiv. _fig._ 3).--This fish is distinguished by
its slender form, and the extreme smallness of the head, as the name
implies. The scales have one row of very thick spines on the posterior
margin; they are more elevated, and shorter than in _B. radians_;
those of the lateral line are pierced by an elongated conical tube,
and are not ramified as in the last species. This ichthyolite, like
the _B. radians_, occurs in the Chalk-marl, and in a similar state of
mineralization.
Smerdis minutus. _Lign. 203._--A pretty ctenoidian fish, from one to
three inches long, about the dimensions of a perch a year old, is very
common in the marls of Aix in Provence, _Wond._ p. 260; and many are
often found grouped together in every variety of position. This species
is characterised by the elevated anterior rays of the dorsal, and the
wide and very forked caudal fin.
Several ctenoidian and cycloidian fishes have been found in the north
of the Brazils, by Mr. Gardiner, in strata probably of the Cretaceous
epoch.
Fossil Cycloid Fishes. (_Poiss. Foss._ tom. v.)--This order comprises
the fishes possessing scales of a cycloid, or circular, form, with
smooth margins, and composed of plates of horn or bone, without
enamel. It contains numerous families, including the _Scaroids_, or
Parrot-fishes, and the _Scomberoids_, or Mackerel tribe, which are
Acanthopterygians, the _Lucioids_, or Pikes, _Clupeoids_, or Herrings,
_Salmonoids_, or Salmon tribe, and the _Cyprinoids_, or Carps, which
are Malacopterygians, as well as other families. The fossil remains of
this order are exceedingly numerous, particularly in the Tertiary and
upper Secondary deposits. A genus of _Salmonidæ_, discovered in the
White Chalk of Sussex, will serve to exemplify the characters of the
fossil cycloidian fishes.
[Illustration: Lign. 203. Smerdis minutus. _Eocene._ (_nat. size_.)
_Aix in Provence._]
Osmeroides. _Plate II._ and _Wond._ p. 344, 347.--Two species of
this genus occur in the Chalk, near Lewes; and principally, if not
exclusively, in the Lower Chalk, without flints. They are exceedingly
beautiful Ichthyolites, and are almost invariably found with the body
but little compressed; the fish, in many examples, is as round and
perfect as when living. The entire cranium, the opercula and branchial
rays, and all the fins are preserved in some examples. These fishes
belong to the Salmon family,[560] and are nearly related to the Smelt
(_Osmerus_); whence the name of the genus. There are two species,
easily distinguishable. The first (_O. Mantelli_, _Pl. II._) has a
short, sub-cylindrical body, and seldom exceeds eight or nine inches in
length; the other (_O. Lewesiensis_) has an elongated and elliptical
body, and sometimes attains a length of fourteen inches. The dorsal fin
too in this species has more rays than in the other. The fossil figured
in _Pl. II_. is a very remarkable specimen of the first species. It
is nine inches in length; and the chalk has been cleared away, so as
to expose the entire fish, six inches in relief above the surface of
the block, _Petrif._ _Lign._ 92, p. 445. The fish is lying on its
back, with the mouth open, and the opercula, or gill-covers, and the
branchial arches expanded; the pectoral and ventral fins, and the
dorsal fin, are in their natural position; the five rays of the dorsal
are erect; of the caudal fin, or tail, but slight indications remain.
There is but one dorsal fin; but in a specimen of _O. Lewesiensis_
there is a trace of the little adipose process observable between the
dorsal fin and the tail, as in the recent species of _Salmonidæ_. A
magnified view of one of the scales is represented _Lign. 185, fig.
4_, p. 567.
[560] They were first described by me in _Foss. South D._ p. 235, tab.
xxxiii. and xl. as _Salmo Lewesiensis_.
Of the Cyprinoids, or fishes of the Carp family (Malacopterygians), the
recent species of which are inhabitants either of fresh-water, or the
brackish waters of the mouths of rivers, many fossil species occur in
the fluviatile and lacustrine deposits of the Tertiary formations. In
their character of omnivorous fishes, the Carps then, as now, formed
the principal mass of the finny population of the lakes, and in their
turn served as food to the carnivorous tribes, as the pikes, eels,
&c. Several species are found in a beautiful state in the schists of
Œningen, and in the Tertiary marls at Aix. Many of the layers of marl
at the latter locality are covered with groups of fishes of the family
_Cyprinodonts_, the recent species of which are of a small size, and
inhabit the fresh-water lakes of temperate zones. _Lign. 184_, p. 562,
represents a portion of a large slab of marl in the cabinet of Sir
R. Murchison, which is covered with scores of a species resembling a
recent fish (_Lebias_) in the profile of its head, and the form of its
fins. It is named Lebias cephalotes, from the relative largeness of its
head. The black appearance of the abdomen in many of these Ichthyolites
indicates the original situation of the intestines and of the liver,
which is largely developed in the fishes of this family, and contains
much colouring matter.
Saurocephalus and Saurodon. _Lign. 204._--In the same quarry, near
Lewes, from which the first entire fish of the Sussex Chalk was
obtained, teeth of a very peculiar character were, many years since,
occasionally discovered.[561] These teeth are of a lanceolate form,
much compressed; with entire, sharp edges, terminating in a point;
the fang is single, and broad; the surface of the crown is glossy,
and marked with fissures filled with chalk (see _Lign. 204, fig.
1_). Teeth of this kind, attached to portions of the jaw, were
subsequently found in the Chalk at Brighton and Lewes. Similar remains
were collected from the Cretaceous marls of Missouri and New Jersey,
in the United States. The American specimens comprised two closely
allied genera, which, from the supposition that the fossils were the
relics of reptiles, were respectively designated _Saurocephalus_ and
_Saurodon_.[562] Examples of the teeth and jaws of both genera have
been discovered in the Sussex Chalk (see _Lign. 204_).
[561] Foss. South D. tab. xxxiii. p. 228.
[562] American Phil. Trans, vol. iii. new series, pl. xvi. on the
Saurodon, by Dr. Hays; and Journal Acad. Sciences, Philadelphia, vol.
iii. on the _Saurocephalus_, by Dr. Harlan.
[Illustration: Lign. 204. Fossil Teeth and Jaws of Fishes. _Chalk._
_Sussex._]
Fig. 1.--Tooth of Saurocephalus lanciformis. _Lewes._
2.--Teeth of Saurocephalus striatus. _Brighton._
Portion of the jaw, with five teeth.
3.--Fragment of a jaw, with two perfect teeth, and the base
of another, of Saurodon Leanus. _Kemptown, Brighton._
4.--Enchodus halocyon. Left branch of the lower jaw,
with teeth; and one front tooth of the opposite portion.
_Lewes._
M. Agassiz retains the names imposed by the American naturalists, and
has placed these genera in the family of Scomberoids (_Mackerel_,
_Swordfish_). They belong to the _Pharyngognathi_ of Muller. The teeth
are disposed in a single row, and fixed in deep sockets by a simple
root, or fang, which is frequently somewhat excavated by the pressure
of a successional tooth. In _Saurodon Leanus_ the crown of the tooth is
angular, and barbed, and supported on a sub-cylindrical shank, or stem
(see _Lign. 204, fig. 3_). The microscopical structure of these teeth
presents that peculiar reticulated disposition of the medullary canals
throughout the entire body of the tooth, which is only found in the
dental organs of fishes.
Hypsodon Lewesiensis. (_Foss. South D._ tab. xlii.)--The Sussex
and Kentish Chalk also contain the remains of a very large fish,
belonging to the Pharyngognathi, with extremely upright, long, conical,
compressed, pointed teeth, which, like those of the Saurodon, are
implanted in sockets. These teeth are commonly of a delicate fawn
colour externally and of a dark brown internally; having a large simple
pulp-cavity. In _Foss. South D._ (tab. xlii.) are represented portions
of an intermaxillary and jaw-bone with teeth; a vertebra, deeply
biconcave; and a large bone, apparently a branch of the _os hyoides_;
all found in the same block of chalk.[563]
[563] A magnificent specimen (now in the British Museum) displays,
on the same slab of chalk, a large portion of the cranium, teeth,
several vertebræ, ribs, and many other bones, belonging to a fish of
considerable magnitude. _Petrif._ p. 444.
Enchodus (_sword-tooth_) halocyon. _Lign. 204, fig. 4._ (Poiss.
Foss. tom. v. tab. xxv^_c_.)--The specimen figured is a portion of
the lower jaw, with one row of elongated, conical, slightly curved,
pointed teeth; the two anterior teeth being much longer and larger
than the others; it affords a good illustration of the dental organs
of _Enchodus_; a genus of Acanthopterygian fishes, the jaws and teeth
of which are often found in the Sussex Chalk. The teeth are of various
sizes, and attached by anchylosis, one row on the premandibular bone,
and another irregular row of smaller teeth to the inside of the lower
jaw. The two anterior teeth are very large, and of a peculiar form:
their base is wide and solid, and the shank of the tooth is suddenly
contracted immediately above, and becomes elongated into a point. These
teeth are generally of a dark colour, have a glossy aspect, and are
very brittle; differing so remarkably in this respect from the shark’s
teeth, with which they are usually collocated, that mere fragments can
be readily identified. The external surface of the lower jaw is marked
with finely granulated, longitudinal ridges or striæ.[564]
[564] A fine example of the lower jaw, with twelve teeth, is figured
_Foss. South D._ tab. xli. and another, with the upper jaw and
teeth, _Geol. S. E._ p. 140. Beautiful figures of the remains of
Saurocephalus, Enchodus, Hypsodon, and many other fine Chalk fishes,
are given in Dixon’s _Fossils of Sussex_, 4to. 1850.
Mr. Toulmin Smith, of Highgate, has in his Museum a portion of the
lower jaw with fifteen teeth of a small individual, imbedded in the
centre of a flint nodule, from Gravesend, which was discovered by
accidentally breaking the stone. The bone of the jaw and the teeth are
of a dead white colour, and appear not to be in the slightest degree
silicified; but in those teeth which are broken the pulp-cavity is
filled with quartz, which must have transuded through the walls of the
teeth.
Ichthyolites of recent species.--The distinguished naturalist to
whose labours in fossil Ichthyology we have been so largely indebted,
states, that of the many hundred species submitted to his notice, but
one can be identified with any fish now living. This conclusion must,
however, be received with some reservation; for, among the fossil
genera, founded on the teeth, there are species which certainly cannot
be distinguished from recent forms. And in the diluvial drift at
Breslau, associated with the bones of the fossil elephant (_Elephas
primigenius_), the remains of a pike, closely resembling the common
European species, have lately been discovered.[565]
[565] Agassiz, _Poiss. Foss._ tom. v. p. 68.
The exception above alluded to, is a little Malacopterygian fish,
rather larger than a Sprat, called the Capelan (Mallotus villosus),
which inhabits the banks of Newfoundland, and other parts of the coasts
of the northern seas. Fossil specimens of this fish.[566] occur in
nodules of indurated marl or clay, on the coast of Greenland.[567] It
is supposed that these Ichthyolites are of very recent date: and that
similar fossils are in the progress of formation.
[566] See _Poiss. Foss._ tom. v. pl. lx., in which the skeleton of the
recent fish, and specimens of the fossil species, are represented.
[567] Similar fossils have been obtained from the "Drift" on the Saco
River, thirty miles north of Portsmouth, New Hampshire. See Lyell’s
Second Visit to the United States, vol. i. p. 29.
Ichthyopatolites, or imprints of the pectoral fin-rays of certain
fishes. Under this name Dr. Buckland described certain problematical
markings observed on a flag-stone from a coal-pit at Mostyn, in
Flintshire, and now in the Geological Society’s Museum. It consists of
curvilinear scratches or imprints, disposed symmetrically at regular
intervals on each side a smooth level space, about two inches wide,
which may correspond to the body of a fish, the pectoral fins of which
Dr. Buckland suggests were the instruments by which the markings in
question were formed.
These scratches follow each other in nearly equidistant rows of three
in a row, and at intervals of about two inches from the point of each
individual scratch to the points of those next succeeding and preceding
it; they are slightly convex outwards, three on each side the median
space, or supposed track of the body of the fish. Dr. Buckland, in
the memoir referred to, shows that these markings cannot be referable
to the imprint of the feet or claws of reptiles, and points out the
structure of the bony anterior rays of the pectoral fins, as in certain
Siluroid and Lophoid fishes, and in the Climbing Perch (_Anabas
scandens_), or the _Hassar_ (_Doras costata_), and refers also to the
ambulatory movements of the common Gurnard, in corroboration of this
opinion.[568]
[568] Proceedings of Geol. Society, vol. iv. p. 204.
* * * * *
_Geological Distribution of Fossil Fishes._--From the incidental
notices of the geological habitats of the fossil fishes enumerated in
our survey of this class of beings, the reader cannot fail to have
remarked, that the most recent strata abounded in forms related to the
inhabitants of the existing seas and rivers; while the most ancient
teemed with species and genera of families altogether extinct, or of
prodigious rarity in the recent fauna.
In general terms, it may be stated, upon the authority of M. Agassiz,
that the Ichthyolites of the Tertiary deposits approach in their
characters to the living genera, but all the species are extinct. The
newer Tertiary, as the Crag, contain genera common to tropical seas,
as the large sharks (_Carcharias_), and eagle-rays (_Myliobates_),
&c. In the Eocene, or most ancient Tertiary, as the London and Paris
basins, Monte Bolca, &c., many of the Ichthyolites are closely related
to recent genera. Of the Chalk fishes, a few only are of recent genera,
but the majority are still allied to Tertiary forms. In the Chalk,
the _Pharyngognathi_, _Acanthopteri_, and _Malacopteri_ are met with
as new types; and indications of the _Hybodontidæ_, _Sauroidei_, and
_Cœlacanthi_ (the last derived from the Devonian, and the other two
from the Carboniferous Limestone) appear for the last time.
The ichthyic fauna of the Cretaceous deposits is closely related by
the majority of its _family_ groups with that of the series of strata
from the Lias to the Wealden, inclusive. In and above the Lias all
the ganoid fishes are _homocercal_. Below the Lias, the genera and
species are far more removed from existing types, and almost all are
_heterocercal_.
Of the eight thousand living fishes known to naturalists, three-fourths
belong to the Cycloid and Ctenoid orders, and of these no species are
known below the Chalk; the other fourth is referable to the Placoids
and Ganoids, of which there are comparatively but few existing
species. Yet fishes of these two orders almost solely flourished
during the ancient Secondary formations; for below the Lias, the
predominant recent orders are altogether absent. Beneath the Coal,
true carnivorous fishes, with trenchant teeth, are almost unknown;
but omnivorous species, with either brush or obtusely conical teeth,
and great sauroid fishes, are the prevailing representatives of the
class.[569] In fine, the Ichthyolites of the different formations
constitute two grand groups, which have their boundary line at the base
of the Cretaceous deposits. The first and most ancient comprises the
Ganoids and Placoids; the second, more intimately related to existing
types, comprehends forms more diversified; these are principally
Ctenoid and Cycloid, with a small number of the two preceding orders,
which insensibly disappear; and their few living analogues are very
distinct from the ancient species. Now, although deductions of this
nature may require to be modified with the progress of knowledge,
yet the generalizations thus obtained are founded on so vast an
accumulation of facts and observations, as to render it improbable that
they will be materially invalidated by future discoveries; for they
remarkably accord with the results derived from the investigation of
the fossil remains of all the other classes of animals. The most modern
deposits contain the remains of animals allied to the existing species;
the most ancient, of forms altogether extinct, or of excessive rarity
in the recent faunas. The discovery of existing species, or genera, in
the most ancient strata, would modify, but not destroy, the inferences
deduced from the facts hitherto obtained; and every geologist is
prepared to find that such may be the case.
[569] In the several chapters on the different formations, as arranged
in the _Wonders_, the student will find succinct notices of the
distribution of the _genera_ of fishes throughout the fossiliferous
deposits. A list of the Chalk species known in 1848 is given at pp.
356-359, _Wond._
Thus of the Sharks, with triangular notched teeth, which are so common
in the Tertiary formations, and were formerly unknown in the ancient
Secondary, one representative has been found in the Carboniferous
system (see p. 595). But, if teeth of this type should hereafter be
discovered in every Secondary deposit, the great preponderance of these
fishes over the Sauroid in the Tertiary, and in the existing seas,
would not be the less remarkable.
* * * * *
On Collecting and Developing Fossil Fishes.--From what has been
advanced, the reader will have obtained a general knowledge of the
fossil remains of this class that are likely to be met with in
particular deposits. Thus, he will expect to find the teeth of large
sharks and rays in the Tertiary clays and sands; and skeletons and
perfect specimens of numerous Ctenoid and Cycloid fishes in the
laminated marls and fine limestones of the same formations. In the
Chalk, with numerous teeth of sharks, he may discover splendid examples
of Cycloid and Ctenoid fishes; and, in the Wealden, large Ganoidian
forms. Passing to the ancient Secondary strata, the extraordinary
buckler-headed and Sauroid fishes will arrest his attention; and
their vestiges will be found, more or less perfect, in the shales and
limestones, and in the indurated nodules of clay and sandstone.
The detached teeth of fishes in Tertiary sands and clays may be easily
obtained entire, and should be arranged in the same manner as the
shells (see p. 442), either in trays, or on boards. The triangular
teeth, with lateral denticles, must be carefully extracted, so as
to preserve those appendages on which the specific and generic
distinctions of many Ichthyolites depend. M. Agassiz particularly
recommends the preservation of all the specimens collected together in
the same locality, as many may probably belong to the same individual,
and thus the dental organization of the original be determined.
Teeth collected from the same stratum in different places, should
not, therefore, be mixed together. Several series of the same kind of
teeth should be preserved, and as many as possible of each kind; for
specimens apparently identical may prove to be highly instructive as a
series. I have often had occasion to regret the disposal of supposed
duplicates, in my earlier researches, which would have tended to
elucidate the characters of those specimens which were retained.
The Ichthyolites, and their detached teeth and fins, in the Chalk and
other soft limestones, may be cleared by means of a penknife or graver
and small sharp chisels. It is preferable to leave the teeth attached
to small blocks of the chalk; as in the examples, figured _Lign.
193_. But to develop the beautiful Chalk Ichthyolites, particularly
those of the Osmeroides, Macropoma, &c. some practice and considerable
dexterity are required. The compressed fishes, as the Beryx, like
those in the Tertiary limestones, often lie in the sedimentary plane
of the stone, and may be sufficiently exposed, by a blow of a hammer
or a pick, to show the nature of the fossil, and admit of being easily
developed. But the fishes with sub-cylindrical bodies very commonly
split asunder in a transverse direction: and those with spinous scales,
as the Macropoma, adhere so firmly to the chalk, that, to display the
external surface of their scales, the surrounding stone must be removed
piecemeal, in the manner described for the Chalk crustaceans (see p.
544). The collector who sees the splendid Chalk fishes in the British
Museum,[570] and learns that they were found in the Chalk of Kent and
Sussex, will be grievously disappointed, upon visiting the quarries
from which they were obtained, if he expects to discover specimens with
any considerable portion of the scales, or body, exposed. It was many
years before the quarry-men acquired the tact they now possess, of
detecting, from very slight evidence, the presence of an Ichthyolite
in a block of chalk: patches of scales, which the quarry-men called
"_bran_," and detached sharks’ teeth, "_birds beaks_," and "_snakes'
tongues_," and teeth of Ptychodus, "_slugs_," being the only remains of
fishes generally observed and laid aside by the workmen.
[570] _Petrifactions_, pp. 441, 444.
The fossil _Salmon_ or _Smelt_ (see p. 626), which may be considered
as one of the most extraordinary of the Chalk fishes found in England,
affords an excellent illustration of the mode of developing the
Ichthyolites of this formation. This interesting fossil is delineated
on a small scale, in three different states, in _Plate II._; and
affords a good practical lesson for the young collector. Among some
blocks of chalk which a recent fall in one of the quarries near Lewes
had brought to light, was a large mass split asunder, and exposing on
each corresponding surface an irregular oval marking of a yellowish
brown colour; this appearance is represented _Pl. II. _fig._ 1_.
Presuming that these markings were produced by a transverse section of
the body of a fish, the two blocks were trimmed into a portable size,
and accurately cemented together with very _hot, thin, fresh_ glue.
When consolidated, some of the chalk was chiselled off in the supposed
longitudinal direction of the enclosed fish, and part of the body,
covered with scales, was exposed, as _Pl. II. fig. 2_. With the view
of ascertaining the extent of the Ichthyolite, some of the surrounding
stone was then removed towards each extremity of the block, and traces
of the fish were discovered, as shown in the same figure. The task of
completely developing the fossil was thus rendered comparatively easy;
the chalk was chiselled, cut, and scraped away, till the perfect fish,
as seen in _fig._ 3, was developed.[571] The block was then reduced to
a convenient size, and the edges sawn smooth. The chalk is easily cut
with a carpenter’s saw; the instrument should be short and strong, and
the teeth of moderate size.
[571] The figure in _Pl. II._ is too small to convey an accurate
idea of this Ichthyolite, which is now in the British Museum; see
_Petrifactions_, pp. 445, 446. M. Agassiz’s figure very inaccurately
represents the original. A beautiful lithograph of this fish, by Mr.
Pollard, of Brighton, was published in the Catalogue of the Mantellian
Museum, 1836.
When a _portion_ of the body of an Ichthyolite of this kind is found in
a block of chalk, and the fracture of the block appears to be recent,
diligent search should be made for the corresponding piece; for it may
probably be found to contain the other part of the fish. A splendid
specimen of _Osmeroides Lewesiensis_, more than a foot long, was thus
obtained. The quarry-men, in a block of chalk which a recent fall had
thrown down, discovered a few inches of the caudal portion of the
body of a fish; on the broken surface of the stone, a section of the
body was distinctly seen, as in the specimen previously described.
Search was made among the fallen masses for the corresponding piece,
but without success. Upon observing the face of the quarry exposed by
the recent fall, on a projecting block, many yards above our reach, a
discoloured spot was indistinctly seen, and it was conjectured that
this might prove to be the other moiety of the Ichthyolite. The workmen
were directed to preserve this block if possible; but it remained _in
situ_ several months, and until the rock was again blasted; when the
stone so long coveted rolled away from the fallen mass, and fortunately
was soon discovered. It proved to be the corresponding portion of the
fish; with the head, opercula, branchial arches, pectoral fins, and
the anterior part of the body covered with beautiful cycloid scales.
In the preparation of fossils of this kind, glue as the cement, and a
paste made of plaster of Paris with thin glue, to fill up the crevices
and strengthen the block, are the materials I have employed. The fossil
remains of fishes in other rocks require to be extracted and developed
in the manner previously directed for the Echinoderms, Cephalopoda,
&c. (pp. 332, 497.)
The collector may be reminded, that _Otolithes_, or ear-stones (p.
574), are found in the Crag of Norfolk, and other Tertiary strata;
and that Coprolites, associated with minute scales, bones, &c. of
small fishes, constitute, in some localities, layers of considerable
thickness and of great extent. The "_bone-bed_" of the Lias, near
Westbury, and that of the Ludlow series on the banks of the Teme, near
Ludlow,[572] are well-known examples of such a deposit.
[572] See Mr. Strickland’s interesting notice of the distribution and
contents of this "bone-bed," in the Quart. Geol. Journ. vol. ix. p. 8
Microscopical Examination.--A few words on the microscopical
examination of the remains of fishes may be useful. The structure of
the large, and the forms of the minute scales, may be seen by a common
lens, and without preparing the specimens. But for the examination
of the intimate organization of scales, teeth, &c. the microscope is
required; and the method directed for the investigation of flint (p.
373) should be employed. The scales, portions of the membranes of
the air-bladder, stomach, &c. and thin chips of the teeth, rendered
temporarily transparent by oil of turpentine, or permanently so
by Canada balsam, should be viewed by transmitted light. But the
intricate structure of the dental organs, the medullary canals, and the
calcigerous tubes, cannot be successfully investigated without the aid
of the lapidary, or the adoption of the process described at page 67
for the preparation of fossil wood for microscopical examination.
BRITISH LOCALITIES OF FOSSIL FISHES.
⁂ The detached teeth, scales, vertebræ, &c. of fishes are so
extensively distributed, that there is scarcely a cliff or quarry
of fossiliferous rock in Great Britain, that does not contain some
examples. The following list of localities must, therefore, be
regarded as merely directing the student to a few places, in which
particular fossils of this class have been discovered.
Abergavenny. _Mt. L._ Teeth of _Psammodus_, _Orodus_, &c.
Armagh, Ireland. _Mt. L._ Numerous teeth and spines.
Arundel, Sussex. _Cret._ Quarries in the neighbourhood; beautiful
Chalk fishes.
Aust Cliff, near Westbury, Somersetshire. _Lower Lias._
_Pholidophorus_, &c. _Base of Lias._ In a layer called the bone-bed,
containing bones, scales, teeth, and Coprolites of fishes. Teeth of
_Ceratodus_, &c.
Axmouth. _Base of Lias: Bone-bed._ Numerous scales, bones, and teeth.
_Saurichthys_, &c.
Barrow-on-Soar. _Lias._ _Dapedius._
Bracklesham Bay, Sussex. _Eocene._ Magnificent specimens of Rays, as
_Myliobatis_, _Aëtobatis_, and of _Chimæroids_ were collected by the
late F. Dixon, Esq., and are now in the British Museum.
Brighton. Cret. Chalk quarries in the vicinity. _Beryx_, _Dercetis_,
_Saurocephalus_, _Saurodon_, and the common species of teeth, &c.
Bristol. _Mt. L._ The usual species of _Psammodus_, _Orodus_,
_Onchus_, &c.
Burdie-house, near Edinburgh. _Carb._ _Palæoniscus_, _Megalichthys_,
_Holoptychius_, &c.
Caithness, Scotland. _Old Red._ _Dipterus_, &c.
Charing, Kent. Many fishes in the Chalk.
Chatham, Kent. _Cret._ _Beryx_, _Hypsodon_, and the usual teeth, &c.
Cheltenham. _Base of Lias._ In the bone-bed teeth, scales, Coprolites.
Clayton, Sussex. _Lower Chalk._ _Beryx microcephalus_, and other rare
Ichthyolites.
Clifton, near Bristol. _Mt. L._ _Psammodus_, _Orodus_, &c.
Cromarty, Scotland. _Old Red._ _Coccosteus_, _Pterichthys_, &c.
Cuckfield, Sussex. _Wealden._ _Lepidotus, Hybodus, Acrodus._
Cullercoats, Durham. _Permian._ _Palæoniscus_, &c.
Dinton, Vale of Wardour. _Purbeck._ _Leptolepis_, _Ceramurus_, &c.
Downton Hall, near Ludlow. _Devonian._ _Cephalaspis_, _Dipterus_, &c.
_U. Sil._ In a quarry on the banks of the Teme, a fish-bed composed of
scales, teeth, and Coprolites, in Upper Ludlow limestone.
Dudley. _Sil._ _Ichthyodorulites_.
Dungannon, Ireland. _Permian._ Quarry at Rhone-hill; numerous small
_Palæonisci_, _P. catopterus_.
East Thickley, Durham. _Magnesian Limestone._ _Palæonisci._
Glammis, Forfarshire. _Devon._ _Cephalaspis, Gyrolepis, Dipterus._
Gravesend and Northfleet. Chalk-pits rich in fish-teeth, &c.
Hastings. _Wealden._ _Lepidotus, Hybodus._
Ilminster, Somerset. _Upper Lias._ _Pachycormus_ and _Leptolepis_.
Leeds, Middleton Quarry. _Carb._ Layers of _fish-coal_, abundance of
remains of _Megalichthys_, _Holoptychius_, &c. (_Geol. Proc._ iii. p.
153.)
Lewes, Sussex. _Cret._ All the fishes of the British Chalk. See
_Wond._ pp. 356-359.
Lyme Regis. _Lias._ _Dapedius_, _Hybodus_, _Squaloraia_; and numerous
other species and genera.
Newhaven, near Leith. _Carb._ On the shore, nodules of ironstone with
fishes and Coprolites. _Amblypterus, Palæoniscus._
Sheppey, Isle of. _Tert._ Numerous teeth of Rays, Sharks, &c., and
other Ichthyolites in great abundance.
Shotover, near Oxford. _Kimmeridge Clay._ _Ischyodus_, _Hybodus_, &c.
Southend, Essex. _Eocene._ Fish-bones and teeth (_Pisodus_, &c.) are
found on the shore along the foot of the cliff.
Speeton, Yorkshire. _Galt._ _Macropoma Egertoni_; and many other
fishes.
Steyning, Sussex. _Cret._ In the marl-pits, Coprolites and teeth of
Sharks are abundant.
Stonesfield. _Great Oolite._ _Hybodus_, _Lepidotus_, _Leptacanthus_,
&c.
Swanage. _Purbeck._ _Lepidotus_, _Hybodus_, _Ophiopsis_, &c.
Thurso, Scotland. _Devonian._ _Asterolepis_, &c.
Westbury, near Bristol. _Base of Lias._ Bone-bed with numerous remains.
Worthing. _Cret._ Beautiful Chalk fishes in the neighbouring quarries.
FOREIGN LOCALITIES.
⁂ Although the present work is expressly designed as a guide to
the British collector, I am induced to subjoin a few foreign localities
of Ichthyolites, that lie within the reach of the continental tourist.
A detailed account of the most celebrated sites is given by M. Agassiz,
Poiss. Foss.
Aix, in Provence. _Tertiary._ Some of the beds of gypseous marl
contain numerous species in abundance.
Eisleben, Upper Saxony. _Permian._ Numerous Ichthyolites in dark shale.
Glaris, Switzerland. _Cret._ Immense numbers of fishes in dark schist.
The specimens are often contorted, from the contraction of their
bodies, during decomposition.
Maestricht (St. Peter’s Mountain). _Upper Cret._ Numerous teeth,
vertebræ, &c. of fishes of the Cretaceous epoch. See _Wond._ p. 309.
Mansfeld, in Thuringia. Permian. Fishes in copper-slate, in great
numbers; many extremely beautiful.
Monte Bolca, or Vestena Nova. _Tert._ The richest mine of Ichthyolites
in the world. A catalogue of the numerous genera and species found
in this celebrated locality, is given in _Poiss. Foss._ tom. iv. pp.
33-52.[573] See _Wond._ p. 265.
Mount Lebanon, Asia. _Tert._ Numerous Ichthyolites, in great
perfection.
Œningen. _Tert. fresh-water._ Many kinds of fishes of the same genera
as those which inhabit the great European lakes; as the Perch, Salmon,
Eel, Pike, Carp, &c. A list of these Ichthyolites will be found in
_Poiss. Foss._ tom. ii. part ii. p. 78. See _Wond._ p. 263.
Saarbrück, in Lorraine. _Carb._ _Amblypterus_, and other Carboniferous
fishes.
Seefeld, in the Tyrol; on the principal road from Insbruck to Munich.
_Lias._ Abundance of fish in bituminous slate.
Stabia, Italy, at Torre d’Orlando, near Castellamare. _Oolite._
Beautiful fishes in fissile limestone.
Solenhofen. _Oolite._ Numerous Ichthyolites; many in great perfection.
See _Wond._ p. 513.
[573] It is necessary to caution the collector against the frauds
practised by the quarry-men, and dealers in fossils, at this and other
celebrated foreign localities. Specimens, apparently perfect, are
ingeniously constructed from the fragments of various examples. The
head of one fish, the body of another, decorated with the fins of a
third, and perhaps the tail of a fourth, of different species, or even
genera, are dove-tailed together, coloured, and varnished, so as to
deceive the common observer, and, occasionally, even the experienced
collector. Sponging the specimens with cold water will often detect the
imposition; for the colour if artificial will be removed, or rendered
paler, while the same process will heighten the natural tints. At
Pappenheim, Solenhofen, and other places, where fossil crustaceans, as
Shrimps, Prawns, &c. are found in such perfection, the imprints of good
specimens are often coloured, and offered for sale; a wet sponge will
speedily detect the imposture.
CHAPTER XVI.
FOSSIL REPTILES; COMPRISING THE ENALIOSAURIANS AND CROCODILES.
"Nous remontons done à un autre âge du monde; à cet âge où la terre
n’étoit encore parcourue que par des reptiles a sang froid--où la mer
abondoit en ammonites, en bélemnites, en térébratules, en encrinites,
et où tous ces genres, aujourd’hui d’une rareté prodigieuse, faisoient
le fond de sa population."--Cuvier, _Oss. Foss._ tom. v. p. 10.
We advance now to the investigation of the fossil remains of the more
highly organized classes of the Vertebrata; the Fishes being the
lowest in the scale amongst the beings characterised by an osseous
skeleton, with a flexible spinal column, composed of articulated bones,
and presenting, in the various classes, orders, genera, and species,
numerous modifications of form and structure. The mineralized relics
of the vertebrated animals consist, for the most part, of single and
displaced bones, or groups of bones and teeth, and the durable portions
of the dermal integuments; entire skeletons being of rare occurrence.
A knowledge of anatomy and physiology, and access to anatomical and
zoological libraries and collections, are therefore indispensable for
the cultivation of this most attractive department of Palæontology.
Fortunately for the English student, this branch of the science, which
a few years since was but little cultivated in this country,[574] has
been greatly advanced, by the liberal support afforded by the British
Association of Science to Professor Owen, whose Reports on the British
Fossil Reptiles and Mammalia, published in the Transactions of the
Association,[575] should be referred to for more precise and detailed
information than can be given in these unpretending volumes. Our
remarks will be limited to a general notice of the fossil remains of
Reptiles, Birds, and Mammals; with descriptions of such characteristic
examples, as will serve to illustrate the nature of the specimens that
may probably come under the notice of the collector; or which, from
their peculiar characters, are objects worthy his special attention.
[574] See _Petrif._ p. 226, note.
[575] Report of the Brit. Assoc. 1839 and 1841; see also Trans. Geol.
Soc. 2d ser. vol. v. p. 515 (1838).
The Age of Reptiles.[576]--The announcement by the illustrious founder
of Palæontology, in the quotation prefixed to this chapter, that there
was a period when the lakes, rivers, and seas of our planet were
peopled by reptiles, and when cold-blooded oviparous quadrupeds, of
appalling magnitude, were the principal inhabitants of the dry lands,
was a proposition so novel and startling, as to require the prestige
of the name of Cuvier to obtain for it any degree of credence, even
with those who were prepared to admit that a universal deluge could
not account for the physical changes, which the crust of the earth had
evidently undergone. Subsequent observations and discoveries have,
however, fully confirmed the truth of this induction, and the "_Age of
Reptiles_" is no longer considered fabulous.
[576] "_The Age of Reptiles_" was the title given by the author to
a popular summary of the evidence bearing on this question: it was
published in the Edinburgh Philosophical Journal, 1831. This name is
now generally employed to designate the geological epochs characterised
by the predominance of oviparous quadrupeds; namely, from the Permian
to the Chalk, inclusive.
In some of the ancient fossiliferous deposits,[577] indications of
the existence of Reptiles are visible, in the indelible markings left
by their footsteps on the muddy banks of rivers, and on the wet sands
of the sea-shores, now in the state of layers of marl and sandstone.
Here and there in the Devonian,[578] Carboniferous, and New Red
formations, teeth and bones are found, presenting unequivocal proofs
of the presence of extinct forms of cold-blooded oviparous quadrupeds.
As we ascend in the secondary formations, we are suddenly surrounded
by innumerable marine and terrestrial reptiles, belonging to species
and genera, and even orders, of which no living representatives are
known. Throughout the Liassic, Oolitic, Wealden, and Cretaceous epochs,
the class of Reptiles was at its fullest development. In the Tertiary
periods which succeeded, the Reptiles approach the recent types, and
their relics are found intermingled with the bones of mammiferous
quadrupeds; thus indicating the commencement of the present condition
and relations of the animal kingdom. Referring the reader to _Bd._ p.
165, and _Wond._ pp. 409-444 and 567-588, for a more comprehensive view
of this subject, we advance to the examination of some of the fossil
genera and species; and we propose, in the first place, to explain a
few essential characters of form and structure observable in those
durable parts of the skeletons which are most frequently met with in a
fossil state; namely, the teeth, jaws, vertebræ, &c., and the osseous
appendages of the dermal system.
[577] Devonian rooks of Elgin, North Britain; and the Lower
Carboniferous of Pottsville, Pennsylvania.
[578] The most ancient Reptile hitherto discovered is the _Telerpeton
Elginense_, from the Old Red of Scotland, which will be described in
the sequel.
The animals comprehended in the Class of Reptilia constitute, according
to Prof. Owen’s arrangement, eight principal groups, or Orders, as
follow:--
The _Batrachia_; Frogs: the body naked, }
with only rudimentary ribs; and with }
two or four feet. Most of these reptiles }
breathe by branchiæ or gills in their }
young state, and by lungs in the adult }
(as for example the Frog); in some (the }
_perenni-branchiata_), the branchiæ are }
persistent through life. } Having a tripartite
} heart (_i. e._ with
The _Ophidia_; Serpents: the body } two auricles and
destitute of feet. } one ventricle), and
} simple transverse
The _Lacertia_ or _Sauria_; Lizards: the } processes to the
body supported by four or two feet, and } cervical and anterior
covered with scales. } dorsal vertebræ.
}
The _Chelonia_; Tortoises: the body }
supported by four feet or paddles, and }
enveloped in two osseous bucklers, }
composed of the expanded bones of the }
sternum and thorax. }
The _Enaliosauria_; Sea-saurians }
(_extinct_): body furnished with four }
paddles, and destitute of scaly covering. }
}
The _Pterosauria_; Wing-saurians }
(_extinct_): body supported on four } Having a quadripartite
feet, the outer finger of each fore-foot } heart (_i. e._ with two
greatly lengthened, and forming a support } auricles and two
for the wing. } ventricles),and double
} transverse processes to
The _Crocodilia_; Crocodiles: body } the cervical and anterior
supported on four partially webbed feet, } dorsal vertebræ.
and encased with an armour of bony plates }
or scutes. }
}
The _Deinosauria_; Great-saurians }
(_extinct_): body supported on four feet. }
Teeth of Reptiles.--The teeth of the animals of this class exhibit
considerable diversity of form, but the characteristic type is that
of a conical, pointed tooth, with a simple root or fang; for, _in no
reptile does the base of the tooth terminate in more than one fang,
and this is never branched_. "Any fossil, therefore, which exhibits a
tooth implanted by two fangs in a double socket, must be mammiferous,
since the socketed teeth of reptiles have but a single fang; and the
only fishes’ teeth which approach such a tooth in form, are those of a
bifurcate base, belonging to certain sharks." (_Owen._)
These dental organs are only fitted for seizing and retaining the
prey or food; for no living reptiles have the power of performing
mastication. In the Crocodiles the tooth has a cylindrical shank,
with a conical, longitudinally striated, enamelled crown, having a
ridge on each side (_Pl. VI. fig. 5_). In the _Labyrinthodon_ (a
fossil reptile), the cone is more curved and pointed (_Pl. VI. fig.
3_); in the _Hylæosaurus_, the shank is cylindrical, and the crown
expanded and lanceolate, with blunt margins (_Pl. VI. fig. 6_); in
the _Megalosaurus_, the tooth is laterally compressed, trenchant, and
slightly inclined backwards like a sabre, with serrated edges (_Pl. VI.
fig. 7_); in the _Iguanodon_, the shank is cylindrical, and the crown
of a prismatic form, greatly expanded, with broad denticulated edges,
and longitudinal ridges on one side (_Pl. VI. fig. 4_, and _Ligns._
221, 223). In the Serpents, the teeth are very long and pointed; in the
Crocodiles and Lizards, may be seen every modification of the conical
form, down to a mere hemispherical tubercle or plate. In the fossil
_Dicynodon_, to be hereafter described, the dental system consists of
but two tusks or canine teeth, like those of the Walrus, implanted in
the upper jaw. The Turtles and some fossil Lacertians are edentulous,
_i. e._ destitute of teeth; their dental organs consisting of the horny
trenchant sheaths with which the jaws are covered.
The teeth are very numerous in reptiles; the individuals of some
species have more than two hundred. In some genera, they are implanted
on the jaws alone; in many, they occupy the palatine, vomerine, and
other bones composing the vault of the mouth, as in certain fishes. The
teeth are generally anchylosed to the bone; but in some genera they are
implanted in distinct sockets, as in the Crocodile and Plesiosaurus; in
others, as in the Ichthyosaurus, they are arranged in a deep furrow,
and retained only by the integuments; in some, they are supported upon
an elevated osseous base. In the Labyrinthodonts, and in the greater
part of the Serpent tribes, the tooth is implanted by the base in a
shallow socket, with which it is confluent.
In most of the Lacertians, or true Lizards, the attachment of the teeth
presents a peculiar modification, of which the lower jaw of the Iguana,
_Lign. 205_, p. 649, affords a good illustration. The teeth are not
placed in sockets, but are attached by the shank to an alveolar plate,
or parapet, that extends along the margin of the jaw, as shown in
_figs._ 1 and 3; the crowns of the teeth project above this plate, as
seen in _figs._ 2 and 4. From the anchylosis of the teeth to the side
of the jaw, the Lizards possessing this dental structure are termed
_Pleurodonts_.[579]
[579] The _Pleurodonts_ are those lizards in which the teeth are
anchylosed to the _side_ of the dentary bone; _Acrodonts_, those
with the teeth fixed to the upper margin or _ridge_ of the jaw-bone;
_Thecodonts_, those having the teeth implanted, either loosely, or
anchylosed to the walls of their sockets. Lacertians are also said to
be _Pleodont_ (having solid teeth), or _Cœlodont_ (hollow-toothed).
In reptiles, we have, therefore, five essential modifications in the
attachment of the teeth; namely, in distinct sockets; in a continuous
groove or furrow; attached laterally by the shank to an alveolar
parapet; anchylosed by the base to a shallow socket; and attached to an
osseous support, without sockets or an alveolar plate.[580]
[580] See the beautiful exemplification of this subject, and the
comparison between the transitory stages of the human teeth in their
progress of development, discovered by Mr. Goodsir, with the permanency
of these conditions in reptiles. Odontography, p. 182.
[Illustration: Lign. 205. The Lower Jaw of an Iguana.
(_From Barbadoes._)]
Fig. 1.--The right branch of the lower jaw of an Iguana; viewed on
its inner aspect. _Nat. size._
_a._ Dentary bone.
_b._ Opercular bone.
_c._ Complementary or coronoid bone.
_d._ Surangular bone.
_e._ Angular bone.
_f._ Articular bone.
2.--The external aspect of the same.
3.--Inner aspect of three teeth (_magnified_) attached to the alveolar
parapet; with the germ of a successional tooth at the base
of the middle tooth; and the sockets of other germs at the
bases of the outer two fully formed teeth.
4.--External view of the crowns of three teeth; slightly magnified.
The intimate structure of the teeth consists of a simple pulp-cavity,
surrounded by dentine, which is permeated by extremely minute
calcigerous tubes, radiating at right angles to the periphery, or
external surface of the tooth. One essential modification of this
structure consists in the intermingling of cylindrical processes of
the pulp-cavity, in the form of medullary or vascular canals, with
the finer tubular structure; as in the tooth of the Iguanodon, _Pl.
VI. figs. 4^b_ and _4^c_. But another modification is that to which
allusion was made when describing the teeth of the Lepidosteus (see
p. 616); in this mode, the dentine preserves its normal character, but
the external cement and surface of the tooth are deeply inflected in
longitudinal folds around the entire circumference; and this structure
is accompanied with corresponding extensions of the pulp-cavity
and dentine into the interspaces of these inflected and converging
folds.[581] This organization is shown, in its simplest form, in the
transverse section of the base of a tooth of the Ichthyosaurus, _Pl.
VI. fig. 9_; and attains its most complicated condition in that of the
Labyrinthodon, _Pl. VI. figs. 3^a, 3^b, 3^c_.
[581] There is a marked difference between the internal structure
of the teeth of true Saurians and of Sauroid Fishes. In the former,
as well as in the _Enaliosauria_, the dentine consists of tubes
radiating from a slender central pulp-cavity to the periphery of the
tooth, without any intermixture of vascular canals. In the sauroid
fish (_Dendrodus_) the central pulp-cavity is produced into numerous
irregular canals, from which vascular sinuses radiate to the
periphery, sending off branches generally at right angles throughout
their entire course; thus, there is an extensive distribution of the
vascular system through the body of the tooth, which does not exist in
any saurian reptile; the nearest analogy is in the labyrinthine teeth
of the gigantic fossil batrachians. (_Owen_: Odontography; and Art.
Teeth, Cyclop. Anat.)
With regard to the mode of development of the teeth, we must briefly
state, that the germ of the new tooth is always produced at the side
of the base of the old one; that in its progress of growth it presses
against the tooth it is destined to supplant, occasions the progressive
absorption of the fang, and ultimately displaces its predecessor;
in some instances, by splitting the crown of the tooth; in others,
by casting it off, according to the oblique or direct position the
new tooth attains in its progress, in relation to its predecessor.
Thus, in the teeth of the Crocodile, the new tooth is generally found
immediately under the conical apex of the crown, and beneath the former
a second successional tooth appears, like a series of thimbles of
various sizes placed one upon another; for in reptiles the production
of new teeth is unlimited. But in the _Pleurodont_ lizards, the new
tooth makes its way obliquely, and the crown is often shed entire.
_Lign. 205, fig. 3_, exemplifies the situation of the successional
teeth in the Iguana.
Lower Jaw of Reptiles.--It is well known that the lower jaw in
mammiferous animals is composed of a single bone on each side; and
that in many genera these pieces become united in front, and form
but one bone in the adult state. But in reptiles, the lower jaw
consists of six distinct bones on each side, as in _Lign. 205_; and
these undergo various modifications of form and arrangement in the
different genera. These bones are distinguished by names which have
reference to their office and situation, and are as follow:--_Lign.
205, a_, the _dentary_ bone, supporting the teeth; _b_, the _splenial_
or _opercular_; _c_, the _coronoid_ or _complementary_; _d_, the
_sur-angular_; _e_, the _angular_; _f_, the _articular_, which forms
the upper portion of the jaw, and includes the condyle. The form and
disposition of these bones in the Iguana, and other true lizards, are
shown in _Lign. 205_; but they differ materially in the Crocodile,
Ichthyosaurus, and other genera. We must restrict our comments to this
short notice, which, however, will suffice to enable the collector who
discovers a fragment of a lower jaw, with any traces of the structure
above described, to determine that it is reptilian; and if any portion
of the _dentary_ bone remains, indications may be obtained of the
family, and perhaps genus, to which it belonged.[582]
[582] To obtain a correct knowledge of the osteological structure of
fossil Reptiles, the student should consult Baron Cuvier’s _Ossemens
Fossiles_, tom. v. To the English reader, the translated abridgement of
Cuvier’s "Fossil Remains of the Animal Kingdom," by E. Pidgeon, 1 vol.
8vo. with plates, 1830, will be found a very instructive volume. See
also Penny Cyclopædia, Art. Saurians.
Vertebræ of Reptiles.--The bones of the vertebral column of this class
of animals present such numerous and important modifications in the
different orders and families, that reference to the works already
cited must be made for satisfactory information on this topic. From the
great number of vertebræ in many reptiles, amounting in the individuals
of some species to nearly two hundred, these bones are the most
abundant fossil relics of these animals to be found in our collections.
The vertebræ are commonly detached, and deprived of their processes;
the solid _centrum_, or body, alone remaining in most examples (as in
_Lign. 206, fig. 8_). Connected series, more or less complete, are
occasionally discovered; and the entire column, in connexion with other
parts of the skeleton, is preserved in many specimens in the British
and other museums.[583] Although, for the reasons previously stated,
minute osteological details cannot be attempted in this work, some
acquaintance with the elementary characters of the bones composing the
spinal column, and of the nomenclature employed to distinguish them,
is necessary to guide the student, and even the amateur collector, in
their researches. I have, therefore, selected a few specimens from
Tilgate Forest in illustration of the elements of Saurian vertebræ, and
of the terms by which the different processes are distinguished; the
general reader will thus be enabled to comprehend the descriptions of
these structures in other works on Palæontology.
[583] See _Petrifactions_, pp. 136-352, and pp. 362-387.
[Illustration: Lign. 206. Fossil Vertebræ or Reptiles. _Tilgate Forest._
_The figures are reduced in the proportions specified by the
fractions._
Fig. 1.--Caudal vertebra of an unknown reptile.
2.--Chevron bone of Iguanodon: seen in front.
3.--Caudal vertebra of Iguanodon, viewed laterally in an
oblique direction.
3_a_.--Front view of the same.
4.--Caudal vertebra of Iguanodon, without either transverse
process or chevron-bone. The letter _o_ marks the deep
hollow left by the removal of the transverse process, at
the suture of the annular part.
5.--Vertebra of Streptospondylus: 1/16 _nat._
6.--Lumbar vertebra of Iguanodon, with the neural spine
broken off.
7.--Vertebra of Streptospondylus: 1/16 _nat._
_c._ The pair of posterior oblique processes (_zygapophyses_).
8.--The bodies of two dorsal vertebræ of Iguanodon: viewed
laterally.
The same letters refer to the same parts in the respective
figures, with the exception of _c_ in _fig._ 7.
_a._ The body, or centrum, of the vertebra: the letter denotes
the anterior part.
_b._ The annular part, formed of the two _neurapophyses_,
which contains the spinal cord.
_c, c._ The articular or oblique processes (_zygapophyses_), which
join to the next vertebra in front.
_d._ The spinous process or neural spine of the annular part.
_e, e._ The transverse process of the annular part.
_f._ The chevron-bone, formed of the two _hæmapophyses_ and
the hæmal spine.
_g._ The double articulating head of the chevron: the passage
left by these processes (_hæmal arch_), seen in the front
view, figs. 2 and 3, is for the passage of the large
blood-vessels which supply the tail.
_h._ The spine of the chevron-bone; the inferior spinous
process, or _hæmal spine_.
_i._ Denotes the medullary cavity of the annular part.
_o, o._ Mark the sutures which connect the annular part with
the body of the vertebra.
_w, w._ Indicate the place of attachment of the chevron-bone.
]
The bones composing the spine, are not only designed to form a flexible
column of support to the trunk, but also to afford protection to the
grand nervous chords constituting the spinal marrow, and which extend
from the brain to the tail, and give off numerous lateral branches in
their course, conferring sensation and motive power to every part of
the frame. To effect this purpose, there is attached to the upper or
dorsal part of each vertebra a bony ring, called the neural-arch, which
is composed of two processes (_Lign. 206, b._), arising from each
side of the body or centrum (_Lign. 206, a._), and which unite above
into a solid piece, termed the spinal process, ox neural spine (_Lign.
206, d._). On each side of the annular paid there is a process, called
the transverse (_Lign. 206, e, e._), for the attachment of muscles;
and in the middle and the posterior dorsal regions of some reptiles,
as, for example, in the existing Crocodiles, these processes articulate
with the ribs. The vertebræ of the tail have, in addition to the above,
an inferior spinous process, termed the chevron-bone (_Lign. 206,
fig. 2_, and _fig. 3, f_.), which gives support to the inferior
layers of the caudal muscles; and, bifurcating at its attachment to the
body of the vertebra, leaves a channel for the passage of the large
blood-vessels, by which the circulation of the tail is effected.
In the generality of living reptiles (as, for example, in the
Crocodile) the bodies of the vertebræ are concave in front, and convex
behind; the bones of the spine being united by ball-and-socket joints;
but, in most fossil reptiles, both faces are either flat, or more or
less concave. In mammalian quadrupeds, the annular part is anchylosed
to the vertebral centre; but in reptiles, it is united by suture,
although, in old subjects, the connecting line is often obliterated. By
reference to _Lign. 206_, and its description, the form, arrangement,
and connexion of the different vertebral elements, in certain fossil
reptiles, may be easily understood. The bones in the vertebral column
of the same animal are considerably modified in the several regions
of the neck (_cervical_ vertebræ), back (_dorsal_ and _lumbar_), and
tail (_caudal_). The cervical are generally of the most complicated
structure; and the caudal, the most simple.
From this exposition, the reader will perceive that every vertebra
consists of the following essential parts: first, the body, or
_centrum_; and secondly, the annular part, or _neural arch_, so named,
because it protects the nervous chord; while a caudal vertebra has,
in addition, the chevron-bone, called also the _hæmal arch_, from its
affording a passage to the large blood-vessels. The bodies of the
vertebræ are in general solid, and consist of the ordinary osseous
structure; but in certain fossil vertebræ the centre of the bone is
filled with calcareous spar, indicating an irregular medullary cavity,
as in the caudal vertebræ of the Ox.[584]
[584] See _Petrifactions_, p. 166, _note_.
The _Sacrum_, which may be termed the key-stone of the pelvic arch, is
formed in existing reptiles by the union of two vertebræ; but in the
Iguanodon and the Hylæosaurus the sacrum is composed of six anchylosed
vertebræ; in the Megalosaurus probably of but five.[585]
[585] Report, Brit. Assoc. 1841, p. 105, and p. 130.
From the sides of the two anchylosed vertebræ which form the sacrum,
strong, short, rib-like processes are given off in those Saurians which
occasionally walk on dry land, and these constitute a firm support to
the hinder extremities.
In the Crocodiles, the four or five vertebræ preceding the sacrum
have no ribs attached to them, and are termed _lumbar_; in the
Lizards, there are but two lumbar vertebræ. A peculiar modification
exists in the first caudal vertebra of the adult Gavial and Crocodile;
the _centrum_ is _convex_ both in front and behind, as was first
demonstrated by me in 1836. See _Wond._ p. 419, and _Petrif._ p. 167.
The last of the anchylosed vertebræ forming the sacrum is concave
posteriorly; hence the necessity of an anterior ball in the first joint
of the tail. (See _Lign. 217_, p. 676, illustrative of _Crocodilus
Hastingsiæ_.) The last _cervical_ vertebra in the Turtles and Tortoises
has a similar construction. This mechanism confers freedom of motion
without risk of dislocation.
Ribs.--The Ribs, which are regarded as appendages to the vertebræ,
(homologues of the pleurapophyses,) are generally slender and round in
the Lizards, and articulate with the spinal column by a single head,
supported on a short convex process or tubercle. In Crocodiles only
of all existing Reptiles, but in several extinct genera, the proximal
end of the rib forms a double articulation, by a distinct head and a
tubercle, with the vertebræ in the cervical and anterior dorsal region
of the spinal column; in the posterior dorsal region the ribs are
attached to the elongated transverse processes of the vertebræ.
As this double articulation of the ribs is invariably associated in
existing reptiles with a heart having double ventricles, while the
lacertian single-headed ribs are in like manner connected with a heart
having but one ventricle, the student will perceive the important
physiological inferences that spring from the discovery of a mere
fragment of a rib, when interpreted by the profound anatomist.[586] In
some fossil reptiles the ribs are flat and very broad; as, for example,
in the Hylæosaurus.[587]
[586] See Brit. Assoc. Report, 1841, and Memoirs, Palæont. Soc.
[587] In Crocodiles the abdominal region is strengthened by slender
ribs (_hæmapophyses_, Prof. Owen), that are affixed to a ligamentous
extension of the cartilaginous sternum, analogous to the _linea alba_
in man; and the Hylæosaurus appears to have possessed a similar
development of the costal elements, for I observed many fragments of
long, slender, sub-cylindrical rib-like bones whilst chiselling off the
stone from this species, and portions of similar bones occur in the
stone around the spinal column from Bolney. In the Maidstone Iguanodon
there are likewise some long slender bones of this character, which I
think must be prolongations of the ordinary dorsal ribs.
Extremities.--The locomotive extremities are variously constructed,
according to the adaptation of the animals to a terrestrial,
fluviatile, or marine existence. The bones of the limbs in the
extinct colossal terrestrial species much resemble those of our large
pachydermata, the Rhinoceros and Hippopotamus. The cylindrical bones
of the extremities in the Crocodilians, and other recent reptiles, are
solid. _i. e._ have no cavity filled with marrow; such also is the case
in the fossil Enaliosaurians; but the thigh-bones and leg-bones of the
Iguanodon, and of other extinct land saurians, h ave a large medullary
canal. Our limits will not admit of further osteological details; and
we are compelled to omit the description of the bones composing the
thoracic and pelvic arches.
Dermal Bones. _Ligns._ 207 and 208. In many of the reptile tribes,
particularly of the Crocodilian or loricated (_mailed_) group, there
are immediately under the external integument or skin a series of
osseous scutes, or scutcheons, variously arranged, which serve as
supports to the integumental scales and spines. In the gigantic Gavial,
that inhabits the Ganges and other rivers of India, and which is
remarkably distinguished from the common Crocodile and Alligator by an
extremely elongated slender muzzle, the nape of the neck is protected
by sixteen or eighteen transverse rows of dermal scutes; and there are
likewise six rows which extend down the back. These bones are deeply
corrugated or sculptured on their upper surface; a structure adapted
for the firm adhesion of the horny integument.
Detached bones of this character occur in the Purbeck strata; and
the first fragments I collected were supposed by me to belong to the
soft-skinned turtles (_Trionyces_); but the subsequent discovery of
perfect scutes demonstrated their analogy to the dermal bones of the
Gavial, and enabled me to determine their true character.
[Illustration: Lign. 207. Dermal Bone of the Swanage Crocodile: 1/3
_nat._
_Purbeck._
(Goniopholis crassidens.)
Fig. 1.--The external aspect.
2.--The inner surface.
_a._--The lateral connecting process.
]
In the splendid specimen of the fossil remains of a Crocodilian reptile
(_Goniopholis_), found at Swanage (_Wond._ pp. 415; and _Petrif._ p.
170), there are numerous dermal examples dispersed among the bones, as
shown in _Petrif._ _Lign._
One of these is figured _Lign. 207_; _fig._ 1 represents the external
surface, which is deeply sculptured by irregular roundish pits or
excavations; the under or inner surface, _fig._ 2, is smooth, but
marked with very fine striæ, decussating each other at right angles, as
in the dermal bones of the Hylæosaurus (_Lign. 208, fig. 1a._).
These scutes differ from those of other recent and fossil Crocodilians,
in a lateral conical projection, marked _a_, _figs. 1, 2, Lign. 207,
which fits into a depression on the under surface of the opposite angle
of the adjoining plate; resembling, in this respect, the scales of the
Lepidotus (see _Lign. 196_, p. 605). Numerous hexagonal and pentagonal
scutes, articulated together by marginal sutures, also entered into the
composition of the osseous dermal cuirass of this reptile, which must,
therefore, have possessed a flexible, yet impenetrable, coat of armour,
capable of affording protection against the attack of any assailant.
In the Oolite, the dermal bones of other slender-nosed Crocodilians
(_Teleosaurus_) are occasionally met with; the outer surfaces of
which are marked with small circular distinct pits; these scutes are
thicker and more rectangular than those above described, and slightly
overlapped each other laterally; they have no connecting process. In
another species one half of the outer surface is smooth, proving that
it was covered to that extent by the adjoining scute.[588]
[588] A description of the dermal bones of British fossil reptiles is
given in Brit. Assoc. Report for 1841, pp. 70, 79, &c.
Dermal Bones of the Hylæosaurus.--Elliptical and circular dermal
scutes, having the under surface flat and the upper convex with
a conical tubercle, were first noticed in the specimen of the
_Hylæosaurus_, figured _Wond._ pl. iv.; and I have since discovered
similar bones associated with other remains of that extraordinary
reptile; reduced figures of two specimens are represented in _Lign.
208, figs. 1, 3_.
[Illustration: Lign. 208. Dermal Bones of Reptiles. _Tilgate Forest._
Fig. 1, and 3.--Dermal bones of the Hylæosaurus: 1/3 _nat._
1_a_.--The under surface of a fragment of a dermal bone, displaying
fine spicula, decussating each other at right angles, and indicating
a similar structure to that of the Curium, in which
the bones were imbedded: nat.
1_b_.---A portion of the same, highly magnified, and viewed by
transmitted light.
2.--Horn of Iguanodon: 1/6 _nat._
4.--A Dorsal Spine of the Hylæosaurus; the original is
thirteen inches long.
]
The structure of these bodies is very remarkable; upon closely
inspecting the under side, and the surface exposed by a transverse
fracture, very minute osseous spicula, decussating each other at right
angles, are distinctly seen; as shown in _Lign. 208, fig. 1a_. In
_fig. 1b_, a thin slice of the same, highly magnified, and viewed
by transmitted light, displays medullary canals, with very fine lines
radiating from them. The peculiar character of this organization
consists in the disposition of the straight bony spicula; an appearance
which first attracted my attention when developing the original
specimen of the Hylæosaurus (see _Geol. S. E._ p. 327), and led to
the discovery of some perfect examples, which otherwise would have
been destroyed. This structure closely resembles that presented by the
ligamentous fibres of the _corium_, or skin, and seems to have resulted
from an ossified condition of the dermal integument. These bones
vary from half an inch to three or four inches in diameter, and were
disposed in one or more longitudinal series on each side the spine,
diminishing in size as they approach the end of the tail.
Dermal Spines of Hylæosaurus. _Lign. 208, fig. 4._--With the dermal
bones above described there are associated in the first discovered
specimen of the Hylæosaurus, flat, thin, angular, osseous plates, from
three to seventeen inches in length; one of which is figured _Lign_
208, fig. 4_. The manner in which they are imbedded in the rocks, in
connexion with other parts of the skeleton, is shown Wond. pl. iv.
and _Geol. S. E._ pl. v. These very remarkable processes appeared to
me to have formed part of a serrated fringe, which extended along the
back of the reptile, analogous to that observable in certain living
lizards (_Wond._ p. 436, _Lign._ 108); and were provisionally described
as such in my first memoir on the Hylæosaurus. This conjecture has
been substantiated by subsequent discoveries, and the true nature of
the large, flat, angular spines, and the conical bones resembling
the horn-cones of ruminants, which occur in the Wealden, is now
established.[589]
[589] See _Fossils, Brit. Mus._ pp. 298, 320.
Horn of Iguanodon.--In this category may be placed the nasal tubercle
or horn of a saurian, like that of the Iguana (_Lign. 208, fig.
2_; _Geol. S. E._ pl. iii.), found with the remains of the Iguanodon,
and probably belonging to that colossal reptile (_Wond._ p. 431; and
_Petrif._ p. 298). It is four inches in length and 3.2 inch by 2.1 inch
in diameter at the base, which is of an irregular elliptical form.
Several smaller specimens have recently been discovered.
Examples of dermal scutes and spines, presenting modifications of form
and structure distinct from those above described, have been brought
to me from various localities of the Wealden; but, as in no instance
a connexion with other parts of the skeleton could be traced, the
particular reptiles to which they belonged cannot be ascertained.
We proceed to notice some of the principal genera of Fossil Reptiles,
especially of those whose remains occur in the British strata; the
arrangement of Professor Owen is adopted for the convenience of
reference to the Brit. Assoc. Reports, 1839 and 1841, which should
be consulted by the student who would acquire a knowledge of this
department of Palæontology. The subject will be considered under the
following heads; namely:--
I. _Enaliosaurians_, or Marine Reptiles; Ichthyosaurus and
Plesiosaurus.
II. _Crocodilians_; Crocodile, Teleosaur, &c.
III. _Deinosaurians_; comprising the Iguanodon, Megalosaurus,
Hylæosaurus, Pelorosaurus, &c.
IV. _Lacertians_; including the Mosasaurus, Rhyncosaurus, &c.
V. _Pterosaurians_; the Pterodactyles, or flying Reptiles.
VI. _Chelonians_; or Tortoises and Turtles.
VII. _Ophidians_; or Serpents.
VIII. _Batrachians_; or the Frog tribe; comprising the Labyrinthodonts.
I. Enaliosaurians.--The extinct marine reptiles comprised in this
order constitute two genera, which are characterized by essential
modifications of osteological structure; they are named Ichthyosaurus
(_fish-lizard_), and Plesiosaurus (_akin to a lizard_). The general
appearance of these beings is so well known, from the splendid
collection of their fossil remains in the British Museum, and the
numerous specimens in provincial and private collections, and by
various works, both scientific and popular, in which their structure
and physiological relations are fully elucidated, that they must be
familiar to every reader.[590]
[590] _Bd._ vols. i. and ii. contain an admirable exposition of
their habits and organization; and Brit. Assoc. Reports, 1839, 1841,
elaborate osteological investigations of both genera. A folio volume on
these extinct Reptiles, with splendid lithographs, by Thomas Hawkins,
Esq., cannot fail to delight the reader by its graphic descriptions and
beautiful illustrations. See also the masterly paper on the Ichthyosaur
and the Plesiosaur, by the Rev. W. D. Conybeare, in the Geological
Transactions, 1st series, vol. v. p. 559, _et seq._
[Side note: ICHTHYOSAURUS. PLESIOSAURUS.]
The living Ichthyosaurus must have borne a resemblance to a Grampus or
Porpoise, with four large flippers or paddles and a long tail, having
a vertical caudal fin of moderate dimensions; the skin probably being
naked and smooth, as in the Cetaceans. The Plesiosaurus presented a
configuration still more extraordinary (_Wond._ p. 575). With a very
small head, it possessed a neck of enormous length, a body of moderate
size, with four paddles, resembling those of turtles, and a very short
tail. They were both marine, air-breathing, cold-blooded, carnivorous,
vertebrate animals; swarming in prodigious numbers during the secondary
epochs, and particularly in the seas of the Liassic period (_Ly._ p.
277, figs. 310, 311). In both genera the construction of the skeleton
presents many important variations from all known recent types; and
should be carefully investigated by the student, who will find in the
Reports of Professor Owen above referred to all the information that
can be desired.[591]
[591] The Penny Cyclopædia, Art. Plesiosaurus, contains an able
abstract of these Reports; and in the _Fossils of the British
Museum_, the student will find a full account of the discovery of
the Ichthyosaur and Plesiosaur, and of the deposits in which they
are chiefly found, as well as detailed descriptions of the most
characteristic structures of the different species.
It will suffice for our present purpose to point out a few important
and obvious characters.
[Illustration: Lign. 209. Eye of Ichthyosaurus. 1/6 _nat._
_Lias._ _Lyme Regis._
Portion of the facial part of the skull of an Ichthyosaurus, showing
the position of the nostril, and of the orbit with its circle of bony
plates, forming the sclerotic coat of the eye.
_n._ The left nasal aperture.]
In the Ichthyosaurus, the nasal apertures or openings of the nostrils
are not towards the snout, as in the Crocodile, but near the anterior
angle of the orbit (see _Lign. 209_), approaching, in this respect,
some of the recent lizards. The orbit is very large, and the sclerotic
coat or capsule of the eye has in front an annular series of bony
plates (_Bd._ pl. x. _figs._ 1, 3), which often occur in their natural
position (_Lign. 209_). This structure is not possessed by fishes,
but is analogous to that observable in the eyes of turtles, lizards,
and many birds; as for example, in the owl and eagle: it confers on
the eye additional power of adaptation and intensity of vision. The
muzzle of the Ichthyosaurus is long and pointed; the lower jaw is
formed of two branches, united anteriorly through nearly half their
length; each branch is composed of six bones, as in the Crocodile and
Lizards, but differently arranged than in those reptiles. The teeth
are very numerous, amounting to nearly two hundred in some species,
and are placed in a single row along the jaws, being implanted in
a deep continuous groove (see _Bd._ pl. xi.). These teeth are of a
pointed conical form, longitudinally striated, with an expanded base
(_Lign. 210_). The new teeth are developed at the inner side of the
base of the old, and grow up and displace them (see _Lign. 210_).
The microscopical structure of the teeth of the Ichthyosaurus is
beautifully illustrated by Professor Owen (_Odontography_, p. 275, pl.
lxiv.). The tooth consists of a pulp-cavity, surrounded by a body of
dentine, which is invested at the base by a thick layer of cement; and
at the crown by a coat of enamel, also covered by a pellicle of cement
3 the pulp-cavity, in fully-formed teeth, is more or less occupied by
coarse bone. The chief peculiarity of this structure consists in the
inflection of the cement into vertical folds at the base of the tooth,
by which the marginal portion of the basal dentine is divided into a
corresponding number of processes; producing, in a transverse section,
the appearance represented in _Pl. VI. fig. 9_. This organization, as
we have previously remarked, is similar to that observable in the teeth
of the _Lepidosteus_ (see p. 616), and of the extinct reptile, called
_Labyrinthodon_, hereafter to be noticed.
[Illustration: Lign. 210. Teeth of Ichthyosaurus and Plesiosaurus,
_nat._
_Lias._ _Somersetshire._
Fig. 1.--Tooth of Plesiosaurus.
1_a_. Transverse section of the lower part.
2.--Tooth of Ichthyosaurus.
2_a_. Transverse section of the middle of the tooth.
3. Vertical section of part of lower jaw of Ichthyosaurus, with a
tooth, illustrative of the mode of dentition.
_a, a, a._ Section of the lower jaw, showing the deep furrow,
_b_ in which the teeth are implanted.
_c._ The canal for the dental vessels.
_d._ Foramen for the passage of vessels to the outer integuments.
_e._ Germ of a successional tooth which has occasioned the
absorption of the inner portion of the base of the mature
tooth, _f_.
]
[Illustration: Lign. 211. Vertebra of Ichthyosaurus. 1/3 _nat._
Fig. 1.--Neural arch and spine.
2.--Body or centrum.
_a._ Socket for the reception of
the corresponding process
of the neural arch.
3.--Vertical section of the centrum.
]
[Illustration: Lign. 212. The bones composing the Pectoral Arch of
Ichthyosaurus.
1/8 _nat._
_s_, sternum.
_cl_, _cl_, clavicles.
_sc_, _sc_, scapulæ.
_c_, _c_, coracoids.
]
[Illustration: Lign. 213. The bones composing the Pectoral Arch of
Plesiosaurus.
1/8 _nat._
_s_, sternum.
_sc_, _sc_, scapulæ or omoplates.
_c_, _c_, coracoids.
_g_, _g_, the glenoid cavities or sockets
for the head of the humerus
or arm-bones.
]
The vertebræ; (_Bd._ pl. xii.; and _Lign. 211_), of which there are
upwards of one hundred and forty in the individuals of some species,
are relatively very short in their antero-posterior diameter (_i. e._
from front to back); and deeply cupped on each articulating face, as in
fishes. The annular part is not united to the body of the vertebra, as
in mammals, nor connected by suture, as in Crocodiles, but terminates
on each side in a compressed oval base, which fits into corresponding
sockets placed on the boundary line of the spinal depression on the
body (_Lign. 210, 2a_); thus completing the medullary canal (see
_Bd._ pl. xii. _fig._ D, E.). Hence the collector may easily recognise
the body of an Ichthyosaurian vertebra, by the pits or depressions on
the sides of the spinal interspace. The first and second vertebra; are
anchylosed together, and have additional subvertebral, wedge-shaped
bones, which render this part of the column a fixed point of
support.[592] (_Bd._ pl. xii. figs. 3, 6.) The form and arrangement of
the bones that enter into the composition of the pectoral and pelvic
arches, and of the paddles, are exemplified in _Bd._ pl. xii.; and
full osteological details are given in _Brit. Assoc. Rep._ 1839, p.
104. The characters of the several bones composing the pectoral arch
of the Ichthyosaur will be readily understood from the accompanying
illustration. The structure of the pectoral arch of the Plesiosaur is
also shown in an accompanying Lignograph, for the sake of comparison.
The bones of a fore-paddle of an Ichthyosaurus are represented (_Lign.
214, fig. 1_). In some species each paddle consists of nearly one
hundred bones. These locomotive extremities are very analogous in their
osteological construction to those of the Cetaceans, but they are
connected with the trunk by means of the glenoid socket formed by the
scapula and coracoid, which are firmly united to the sternum; whereas
in the Cetaceans the pectoral fin is only attached to a simple scapula,
which is merely suspended in the muscles. This structure, together
with the presence of a clavicle in the Ichthyosaurus (see _Lign.
212_), which is wanting in the Cetaceans,, indicates, in the opinion of
Professor Owen, that this marine fish-lizard was capable of some degree
of locomotion on the land; and that it might have resorted to the
shore to deposit its eggs, or, like the Crocodile, to sleep. From the
frequent occurrence of a dislocation or abrupt bend of the vertebral
series of the tail, at about one-third of its length from the end,
supposed to have been produced by the weight of a large fin, during
the progress of decomposition, and from the terminal caudal vertebræ
being laterally compressed, it is inferred that the Ichthyosaurus had a
vertical fin at the extremity of the tail, which would thus be rendered
a powerful instrument of progressive motion.[593] From the appearance
of the _Coprolites_, which occur abundantly with the skeletons of these
animals, it is obvious that the intestinal canal in the Ichthyosaurus
was furnished with spiral valves, as in the Sharks; and the comminuted
bones and scales in the coprolites prove that fishes constituted the
principal food of these marine reptiles.
[592] This structure was first demonstrated by Sir Philip Egerton. See
Geol. Trans. 2d series, vol. v. p. 187, pl. xiv.
[593] Geol. Trans. 2d ser. vol. v. p. 511, pl. xlii.
[Illustration: Lign. 214. Paddles of Ichthyosaurus and Plesiosaurus,
1/8 _nat. size_.
_Lias Shale._ _Lyme Regis._
Fig. 1.--Left fore-paddle of the Ichthyosaurus.
2.--Left fore-paddle of the Plesiosaurus.
]
The Ichthyosaurus has abdominal ribs (p. 656, note), as in the
Crocodile, and it is therefore inferred that, if oviparous, it did not
produce ova in such immense numbers as the Batrachians, &c. A specimen
found by the late Mr. Channing Pearce renders it probable that the
Ichthyosaurus may have been viviparous. A remarkably perfect adult
Ichthyosaurus, examined by this gentleman, contained the bones of a
fœtus (a few inches long) _in the cavity of the pelvis_. This specimen
is in the collection of Mr. Pearce, at Bath. Remains or traces of the
dermal integument have been discovered in some examples from the Lias
of Barrow-on-Soar, Lyme Regis, Ilminster, and the neighbourhood of
Tewkesbury.[594]
[594] See Mr. Coles’s interesting paper on the Skin of the
Ichthyosaurus, in the Quart. Journ. Geol. Soc. vol. ix. p. 79.
[Illustration: Lign. 215. Hinder Paddle of an Ichthyosaurus
(1/3 _nat._): with the impression of its integuments. _Lias._
_Barrow-on-Soar._
(_From Geol. Trans. 2d ser. vol. vi. pl. xx._)]
Integuments of the Paddle.--The importance of carefully examining the
surrounding stone before removing vegetable or animal remains from
the matrix in which they are imbedded, and which has so often been
insisted upon in the preceding pages, is strikingly exemplified in the
highly interesting example of the hinder paddle of an Ichthyosaurus
(_I. communis_) discovered by Sir Philip Egerton. _Lign. 215_ is
reduced from the exquisite representation of the specimen accompanying
the original memoir by Prof. Owen on this fossil, in the Geological
Transactions. The specimen consists of the phalangeal bones of a
posterior paddle, with the impression of the soft parts or integuments
in their natural position; _a_, marks the termination or distal
extremity of the fin, consisting entirely of the softer integuments;
these gradually widen and expand to receive the terminal rows of
the phalangeal ossicles or bones, marked _b_. The upper border of
this integumentary part of the paddle (_c_) is formed by a smooth,
well-defined line, apparently a mere duplicature of integument. But
the lower margin (_d_) exhibits the impressions of a series of rays,
by which the fold of integument was supported; these rays bifurcate
as they approach the margin of the fin, and were probably either
cartilaginous, or composed of an albuminous horny tissue, like the
marginal rays in the fins of Sharks. Dr. Buckland detected remains of
the dermal integument of an Ichthyosaurus in a specimen from the Lias
at Barrow-on-Soar (_Bd._ ii. p. 22, pl. x.); and in a fine skeleton
with the four paddles (now in the British Museum), which I obtained
from that locality, there were decided traces of the carbonized
integuments around each paddle, but which were, unfortunately,
chiselled away, in developing the bones, before I was aware of their
true nature.
In Mr. Coles’s paper, already referred to, the student has an
instructive instance of the value of a careful examination of faint or
obscure traces of organic matter accompanying these saurian remains,
and how such an examination should be made. The Plate illustrative of
the Memoir exhibits the minute, hooked, conical bodies, that form the
dense felt-like mass which the black film, frequently accompanying
these fossil bones, appears to consist of, when seen under the
microscope. To what extent this substance entered into the constitution
of the integuments, or of the exact relation of these "setiform scales"
to the surface or the interior of the skin, our present knowledge does
not enable us to judge.
[Sidenote: PLESIOSAURUS.]
Plesiosaurus. (_Bd._ pl. xvi.--xix.)--The animals of this genus present
in their osteological structure a remarkable deviation from all known
recent and fossil reptiles; uniting the characters of the head of
a lizard, with the teeth of a crocodile, to a neck of inordinate
length, with such modifications of the ribs, the pectoral and pelvic
arches, and the paddles, as to justify the graphic simile of Professor
Sedgwick, that the Plesiosaurus might be compared to a serpent threaded
through the shell of a turtle.
The character which immediately strikes the observer, is the
extraordinary length of the neck, and the relative smallness of the
head. The neck, which in most animals is formed of but five vertebræ,
and in the extremest recent example, the Swan, does not exceed
twenty-four, is in the Plesiosaurus composed of from twenty to forty;
and, in some species, is four times the length of the head, and equal
to the entire length of the body and tail; while the length of the
head (in _P. dolichodeirus_) is less than one-thirteenth of the entire
skeleton. The skull resembles that of the crocodile in its general
form, but is relatively smaller, and is more related to the lacertian
type. The parietal bone is more triquetal than in the crocodiles;
but the zygomatic bone is attached to its lower end. The breathing
apertures are situated anterior to the orbits, on the highest part of
the head. The lower jaw has the usual structure of the Saurians; but
the dentary bone is greatly expanded anteriorly, and united in front
(see _Bd._ pl. xix.). The teeth are implanted in separate sockets, as
in the crocodile, and there are from thirty to forty on each side the
jaws. They are conical, slender, long, pointed, slightly recurved,
and longitudinally grooved from the base upwards; having a long round
fang. The pulp-cavity is long and single, surrounded by a body of firm
dentine, covered on the crown with a layer of enamel, and at the base
with cement (_Odont._ pl. lxxiv.). The dentition in the Plesiosauri
differs from that of the Crocodiles, in the successional teeth emerging
through distinct apertures on the inner side of the sockets of their
predecessors, and not through the pulp-cavity. The vertebræ are
relatively longer than in the Ichthyosaurus, and their articular faces
are either flat, or slightly excavated towards the periphery, with a
gentle convexity in the centre (_Foss. Til. For._ pl. ix. fig. 4).[595]
[595] For details, see Brit. Assoc. Rep. 1839, p. 50.
The caudal vertebræ have two distinct hæmapophyses, not united into a
chevron-bone.
The cervical ribs, or hatchet-bones, are attached by two articular
facets to the bodies of the vertebræ, but with a very narrow space
between; scarcely large enough even for the passage of the sympathetic
nerve; and apparently not sufficient for the vertebral artery.
The _pectoral arch_ is remarkable for the pair of elongated and broad
coracoid bones (_Bd._ pl. xvii. and _Lign. 213_); indeed the coracoids
attain their maximum of development in the Plesiosaurus. The _ribs_,
which are very numerous, and extend throughout a great portion of
the vertebral column, are connected, anteriorly, in the abdominal
region, by several slender bones, called _costal-arcs_, consisting
of six or seven pieces to each pair of ribs; the Ichthyosaurus has a
similar structure, but the arcs are composed of but five pieces. As
these connecting bones are so constructed as to admit of a certain
degree of gliding motion upon each other, it is inferred that, by this
mechanism, considerable expansion of the pulmonary cavities in these
air-breathing marine reptiles was obtained (_Bd._ pl. xviii. fig. 3).
The paddles are composed of fewer and more slender bones than in the
Ichthyosaurus, and must have been of a more elegant form, and possessed
greater flexibility (_Lign. 214, fig. 2_). The wrist (_carpus_)
consists of a double row of round ossicles, which are succeeded
by five elongated metacarpal, and these by numerous, slender and
slightly-curved phalangeal bones.
Sixteen species of Plesiosaurus and ten of Ichthyosaurus have been
discovered in the British strata, and nearly forty are now known;
their geological range is from the Lias to the Chalk, inclusive.[596]
Their remains are found most abundantly in the Lias and Oolite. I have
collected many Plesiosaurian vertebræ in the Wealden, and in the Green
Sand of Farringdon. No traces of Ichthyosauri have been observed in the
Wealden; but vertebræ, and jaws with teeth, occur in the lower Chalk
and Galt of Kent and Cambridgeshire.[597] On the Continent the remains
of Enaliosaurians have also been discovered in the same formations.
[596] See _Petrifactions_, for an account of the specimens in the
British Museum.
[597] Brit. Assoc. Trans. 1845, Sect. p. 60. The Enaliosaurian bones
and teeth found in the Cretaceous deposits of England have been
fully described and illustrated by Prof. Owen, in Dixon’s _Fossils
of Sussex_, &c., and in his Monograph on the Fossil Reptiles of the
Cretaceous Formation, Palæontographical Society, 1851.
Pliosaurus.---This name designates a gigantic extinct reptile, of
which the upper and lower jaws, with teeth, considerable portions of
the vertebral column, and many bones of the extremities have been
discovered in the Kimmeridge clay of Oxfordshire, and are preserved in
Dr. Buckland’s museum. The teeth resemble those of the Plesiosaurus
in their general aspect, being of a conical form, longitudinally
grooved, and having a long fang; but they are readily distinguished by
the subtrihedral form of the crown, produced by the smooth, flat, or
slightly convex external surface; they approach in this respect the
tooth of the Mosasaurus; from the latter, however, even fragments may
be known by the presence of longitudinal ridges. The animal itself was
an enormous marine reptile, allied to the Plesiosaurians, but more
nearly related to the Crocodilians.[598]
[598] Brit. Assoc. Rep. 1841, p. 60. Odont. pl. lxviii.
II. Crocodilians.--The loricated, or mailed, Saurian reptiles, viz.
the Alligators, Crocodiles, and Gavials, are well known as the largest
living forms of cold-blooded oviparous quadrupeds.[599] No relics of
any recent species have been observed in a fossil state; except that of
the Gangetic Gavial, which has been found fossil in the Sub-Himalayas
by Capt. Cantley and Dr. Falconer; but remains of Crocodilians of
the existing generic type, having the spinal column composed of
concavo-convex vertebra; (i. e. united to each other by a ball and
socket-joint), the convexity being behind, or towards the tail, have
been found in the London Clay at Hackney and the Isle of Sheppey, and
in the eocene deposits on the coast of Western Sussex and Hants.[600]
But the Crocodiles of the Wealden, Purbeck, Oolite, and Lias differ
materially in their osteological characters from the recent species,
particularly in the structure of the vertebral column; which in one
genus is composed of concavo-convex vertebra; placed in a reversed
position to those of the existing species, the ball or convexity
being anterior, or directed forwards. In the other genera, both the
articular faces of the vertebræ are either flat, or concave.[601]
(_Geol. S. E._ p. 296.)
[599] A detailed and philosophical examination of the osteology of
the recent Crocodilia has lately been given to the scientific world
by Prof. Owen, in his Monograph on the Reptilia of the London Clay,
published by the Palæontographical Society of London, 1850. A condensed
notice, by Prof. Owen, of the dental apparatus of the Crocodilians, is
to be found in the _Cyclop. Anat._ Art. Teeth.
[600] See Brit. Assoc. Rep. 1844, Sect. p. 50; and 1847, Sect, p. 65.
[601] Cuvier, Oss. Foss. tom. v. p. 153; on the fossil Crocodiles of
Honfleur, which comprise both the types alluded to in the text.
Vertebræ of two species of Crocodilians or Alligators have been found
in the cretaceous Green Sand of the United States: these are of the
true procœlian[602] type, as in the existing species; but they present
peculiar characters in the modification of the apophyses.[603]
[602] Procœlian, concave before: amphicœlian, concave at both ends
platycœlian, flat in front and concave behind.
[603] See Quart. Geol. Journ. vol. v. p. 380, pl. x.
[Illustration: Lign. 216. Skull and Jaws of Teleosaurus. 1/8 _nat._
_Lias._ _Whitby._
Fig. 1.--Upper view of the cranium of Teleosaurus.
_c_, occipital condyle.
_t_, _t_, temporal fossæ.
_o_, _o_, orbits.
_n_, nasal apertures.
2.--Muzzle or anterior extremity of the jaws of _Steneosaurus_.
3.--The same of Teleosaurus.
4.--Lateral view of the cranium and lower jaw of Teleosaurus.
]
With this exception, the Crocodilians with broad muzzles, as the Cayman
and Alligator, have no representatives below the Tertiary formations;
the _Crocodilia_ of the Secondary deposits being all referable to the
division having elongated beaks, like the recent Gavials (_Bd._ p.
250). The fossil Crocodiles of the latter type are arranged in two
genera; namely, Teleosaurus[604] (_Lign. 216, fig. 3_), in which
the nasal apertures terminate in two orifices, (not blended into a
single opening as in the recent species,) in front of the nose; and
Steneosaurus (_Lign. 216, fig. 2_), in which the breathing canals end
in two nearly semicircular vertical openings at the extremity of the
muzzle. (See also _Bd._ pl. xxv.)
[604] The skeleton of a recent Gavial, and that of a Teleosaur, are
represented on one plate, for comparison, in Prof. Owen’s Monograph,
_loc. cit._
The British fossil species, most nearly related to the recent, occur
in the Lower and Middle Eocene of the South-East of England. Two fine
specimens of the skull of _Crocodilus toliapicus_, Cuvier and Owen
(_C. Spenceri_ of Dr. Buckland), have been found at Sheppey, as well
as a skull of _C. champsoïdes_ (Owen), and numerous vertebræ referable
to each species. The eocene deposits of Hordwell Cliff have yielded
the _Crocodilus Hastingsiæ_,[605] and the _Alligator_ _Hantoniensis_
(_Petrif._ p. 467; and _Charlesworth's Geol. Journ._ pl. i.); and the
remains of a Gavial (_Gavialis Dixoni_, Owen, in Dixon’s _Foss. Suss._)
have been found at Bracklesham.[606]
[605] This fossil Crocodile supplies a good illustration of the
biconvex body of the first caudal vertebra already described as
peculiar to these loricated reptiles, see page 656; and I have
subjoined _Lign. 217_ in illustration of this structure.
[606] Most of these valuable fossils are in the British Museum. They
are all described in detail and most elaborately illustrated in Prof.
Owen’s Monograph, already referred to.
[Illustration: Lign. 217. First Caudal Vertebra of Crocodilus
Hastingsiæ.
1/3 _nat._
_Eocene._ _Hordwell Cliff._
_s_, spinous process, or neural spine.
_z_, anterior zygapophysis or oblique process.
_z^1_, posterior zygapophysis.
_d_, left diapophysis, or transverse process.
_a, p_, body or centrum, convex at both ends.
]
In the strata of Tilgate Forest, associated with innumerable remains of
reptiles of various kinds, teeth of the Crocodilian type, belonging to
two genera, are not uncommon.[607] The first kind (_Suchosaurus_[608]
_cultridens_ of Prof. Owen) is a tooth about an inch in length, of a
slender acuminated form, compressed laterally, and gently recurved,
with a sharp edge in front and behind; resembling, in its general
figure, the tooth of a Megalosaurus, with the serrations on the edges
worn off (_Pl. VI. fig. 7_). The sides of the crown are marked with a
few longitudinal grooves. Some biconcave vertebræ found in the same
quarries, and characterized by the compressed wedge-shaped form of the
centre (_Foss. Til. For._ pl. ix. _fig._ 11), are supposed by Professor
Owen to belong to the same reptile as the teeth above described; but it
is hazardous to pronounce on the identity of these detached teeth and
bones, without more corroborative proof than has hitherto been obtained.
[607] Foss. South Downs, p. 50. _Foss. Tilg. For._ p. 64; pl. v. figs.
1-3, 7. _Cuv. Oss. Foss._ tom. v. p. 161, pl. x. See also Owen's later
examination of these remains, _Report Brit. Assoc._ 1811, p. 67; and
_Cyclop. Anat._ Art. Teeth.
[608] Brit. Assoc. Rep. 1841, p. 68. _Sucho-saurus_ is derived from
_Suchus_, or _Suchis_, the name given by Strabo to the sacred crocodile
of the Egyptians.
Swanage Crocodile. (_Goniopholis crassidens._) _Petrif._ p. 170,
_Lign. 38._--Under this name, the second species of Crocodilian teeth
will be considered; the discovery of a considerable portion of a
skeleton of a reptile with teeth of this form (_Wond._ p. 416), in
a quarry near Swanage, having disclosed some of the most important
osteological characters of the original. These teeth are distinguished
from the former by their cylindrical base, and rounded, obtuse, conical
crowns (_Petrif._ p. 171): they somewhat resemble in form those
of the Crocodile, but the crown is strongly marked with numerous,
well-defined, longitudinal grooves and ridges; and there is a sharp
ridge on the middle of each side. A small specimen, broken off at the
base, is represented _Pl. VI. fig. 5_; it shows the smooth cylindrical
base of the tooth, which is covered with cement, and the finely
striated enamelled crown; some of the teeth are more than two inches
in length, and one inch in diameter at the base (_Foss. Til For._ pl.
v. figs. 1, 2). I have found these teeth in numerous localities; they
are always well preserved, with the ridges sharp, and have a high
polish (_Geol. I. Wight_, p. 357, _Lign._ 30); a series of successional
teeth may often be detected in the pulp-cavity (see _Wond._ p. 414).
The detached teeth, and fragments of dermal bones (_Lign. 207_),
which, from their constant occurrence with this species, I had been
led to consider as belonging to the same reptile, were the only
relics that had come under my observation, until the discovery of the
Swanage specimen above mentioned.[609] On the two corresponding slabs
containing this fine fossil are imbedded many detached teeth; a portion
of the left side of the lower jaw, with two teeth in place; ribs and
numerous vertebræ, which are biconcave, and have an irregular medullary
cavity in the centre of the body; chevron bones resembling those of
the Crocodile; the bones of the pelvic arch, and some of those of the
extremities. With these are the remains of the osseous dermal cuirass,
consisting of numerous scutes (figured and described p. 657, _Lign.
207_), scattered at random among the other relics of the skeleton; some
having the inner, and others the external surface exposed; several of
these bones are perfect, and exceed six inches in length, and two and
a half in breadth. Numerous scales of a small Ganoid fish (_Lepidotus
minor_), common in the Purbeck strata, are also intermingled with these
remains. This reptile is named _Goniopholis crassidens_, by Professor
Owen.[610]
[609] Now in the British Museum: see _Petrif._ p. 170. A lithograph
of one of the slabs was given in the third edition of the Wonders of
Geology, 1839.
[610] _Gonio-pholis_:--_angle-scute_. Brit. Assoc. Rep. 1841, p. 72.
Both the slabs of the Swanage specimen are admirably arranged in the
same case in the British Museum, with bones and scutes of this reptile
from Tilgate Forest; there can be no doubt that the entire lower jaw
of the Swanage reptile might have been obtained if the quarry-men had
taken the precaution of examining the adjoining block of stone.
Pœcilopleuron.--The remains of an allied genus of Crocodile, the
_Pœcilopleuron Bucklandi_ (of Deslongchamps), occur in the Oolite,
near Caen, Normandy. This reptile, like the Goniopholis, had biconcave
vertebræ, with a large medullary cavity in the middle of the centrum.
The body of the vertebræ is contracted in the middle, the neural arch
anchylosed, with no trace of suture, and with a thin spinous process,
which is remarkable for its backward inclination. Vertebræ of this
character also occur in the Wealden strata of Tilgate Forest and the
Isle of Wight.[611]
[611] Brit. Assoc. Rep. 1841, p. 84. _Foss. Til. For._ pl. ix. fig. 8,
represents a caudal vertebra.
Teleosaurus. (_Bd._ pl. xxv.)--In the Oolite of England and the
Continent, the remains of a genus of extinct reptiles, having, like
the recent Gavial, long slender muzzles, have been discovered in
several localities. These fossils consist of the osseous scutes of
an imbricated dermal cuirass; of the cranium and jaws with teeth; of
the vertebral column; and many other bones. The characters of the
dermal scutes, and of the muzzle with its terminal nasal apertures,
have already been described (p. 659, and p. 676). There are several
species of _Teleosaurus_; a splendid specimen of _T. Chapmanni_,
fifteen feet long, from the Lias-shale on the Yorkshire coast, is
preserved in the Whitby Museum; and there are interesting examples
in the British Museum.[612] Teleosaurian remains have been found in
the Oolite at Stonesfield, and at Deddington, Oxfordshire; and Mr. C.
Moore, of Ilminster, whose museum is rich with perfect Ichthyosaurs
and Fishes from the Upper Lias of the neighbourhood, has been highly
successful in developing some charming specimens of small Teleosaurs
from out of the same deposit. In the Oolite of Caen, in Normandy, very
fine specimens of _T. Cadomensis_ have been discovered; and from these
the illustrious Cuvier first determined the character and affinities
of the original.[613] The British Oolite contains also the relics of a
reptile with biconcave vertebræ, belonging to the genus _Steneosaurus_:
the cranium with the jaws and teeth have been found in Kimmeridge clay,
at Shotover (_Bd._ pl. xxv.).[614]
[612] _Petrifactions_, p. 178.
[613] Oss. Foss. tom. v. p. 127.
[614] Report Brit. Assoc. 1841, p. 82.
From the Jura limestone at Monheim, in Franconia, the remains of a
small Crocodilian reptile (Teleosaurus priscus), with a long slender
muzzle, have been obtained. In a specimen[615] from the former
locality, the skull, jaws with teeth, the entire vertebral column, and
many parts of the skeleton are preserved: the entire length is but
three feet.
[615] Now in the British Museum: see _Petrif._ p. 178, where a detailed
description of this unique fossil is given. See also _Ossem. Foss._
tom. v. pl. vi.
Streptospondylus, _Lign. 206, figs. 5, 7._--Baron Cuvier in his
celebrated work, "_Recherches sur les Ossemens Fossiles_," has given
an elaborate description of the remains of two kinds of slender-nosed
Crocodilians, from the Kimmeridge clay of Honfleur, and the Oxford clay
of Havre.
The specimens consist of the jaws with teeth, vertebræ, and some bones
of the extremities.[616] In one species, the vertebræ are biconcave; in
the other, they are convexo-concave, and present a remarkable deviation
from the recent Crocodilian type, namely, that they are placed in a
reversed position,--the convex face of the vertebra being directed
anteriorly, or towards the cranium, and the concavity posteriorly;
the name of the genus, _Streptospondylus_ (reversed-spine), denotes
this peculiarity of structure. The bodies of three or four large
convexo-concave cervical vertebræ, were discovered in the Tilgate
strata many years since, and are described in my various works (_Geol.
S. E._ p. 300); but no suspicion was then entertained of their
belonging to this genus, although I had repeatedly compared them with
the figures of the Honfleur crocodile,[617] the imperfect state of
the processes obscuring their true characters. Professor Owen first
detected the true character of these Wealden vertebræ, in a large
cervical, six inches long (now in the British Museum), in which two
oblique processes are preserved on the concave end of the bone, their
flat, oblong, articular faces, are directed downwards and outwards,--a
character which at once proves them to be the posterior pair, for the
anterior oblique processes would be directed upwards and inwards.[618]
Vertebræ of the same species occur in the Wealden of the Isle of Wight;
and of another species in the Oolite at Chipping Norton, and in the
Lias of Whitby.
[616] Oss. Foss. tom. v. p. 143, pl. viii. ix.
[617] Reduced figures of two of these vertebræ are given in _Lign.
206_, _figs._ 5 and 7, p. 653.
[618] Brit. Assoc. Rep. 1841, p. 92. The position of the articulating
surfaces of the oblique processes (_zygapophyses_) in more perfect
specimens, subsequently discovered in various localities of the
Wealden, established the existence not only of a saurian allied to the
Streptospondylus, but also of other reptiles whose spinal column was
wholly or in part made up of vertebræ which were convex in front and
concave behind, as in the cervicals and anterior dorsals of certain
mammalia. Some of these fossil vertebræ Dr. Melville has referred,
with great probability, to the cervical region of the Iguanodon (see
_Petrif._ p. 259); others cannot at present be satisfactorily assigned
to any known genus of reptiles.
A concavo-convex caudal vertebra, with the relations of which I am
unacquainted, was found in the same quarry in Tilgate Forest; a reduced
outline of this unique fossil is given in _Lign. 206, fig. 1_. The
centrum is of a sub-cylindrical form, and the articular face in front
is concave, and that behind, convex; with a chevron-bone that is
anchylosed to the body of the vertebra, as in some of the caudals of
the Mosasaurus, and terminates in an inferior spine (_f._); the pair
of anterior oblique processes remains; the neural spinous process is
destroyed.
Cetiosaurus.--From a considerable number of vertebæ and bones of
the extremities of some gigantic aquatic reptiles, discovered in
the Oolite in various places in Oxfordshire, Northamptonshire, and
Yorkshire, the present genus was established; the name being intended
to indicate a distant general resemblance of these extinct Saurians to
the Cetaceans.[619] The vertebra; differ from those of the Iguanodon
in having their articular faces of a sub-circular form, and the body
relatively short; the anterior face is nearly flat, and the posterior
concave, in the dorsal vertebra;; but in the caudal both faces are
concave, and have a well-defined elevated margin, which gives the
body a deeply excavated character, easily recognizable. Vertebræ of
this kind were among my earliest discoveries in the strata of Tilgate
Forest. (_Geol. S. E._ p. 282.) Some specimens are eight inches in the
transverse diameter of the articular face, and but four and a half
inches in the antero-posterior length of the body.[620] The original
animals are supposed to have been of aquatic, and probably of marine
habits, on the evidence of the sub-biconcave structure of the vertebræ
and of the coarse cancellous tissue of the long bones, which are
destitute of a medullary cavity. They must have rivalled the modern
whales in bulk, for some specimens indicate a length of forty or fifty
feet; they are supposed to have had web-feet, and a broad vertical
tail.[621]
[619] Proc. Geol. Soc. vol. iii. p. 457.
[620] The osteological characters of these remains, and the
physiological relations of the original animals, are described in
_Brit. Assoc. Rep._ 1841, pp. 94-102.
[621] Brit. Assoc. Rep. 1841, p. 102.
Polyptychodon.[622]--The remains of another gigantic marine Saurian
have been discovered in the Green Sand at Hythe, in Kent; they consist
chiefly of the bones of the pelvis and hinder extremities.[623] The
femur must have been nearly four feet in length. The long bones have a
cancellated structure, without a medullary cavity 3 the outer surface
is finely striated. Probably in a recent state the cells were filled
with oil, as in the _Cetacea_. Neither the vertebræ nor the teeth of
this reptile are known; but, provisionally, these remains have been
referred to the same animal as that to which the large, conical,
longitudinally ridged teeth belonged, which have been found in the
Kentish Rag, at Maidstone, and in the Chalk of Sussex, and have been
named _Polyptychodon continuus_.[624] Teeth of _P. interruptus_ are
not unfrequent in the Cretaceous series; and a portion of the lower
jaw of this species, from the Chalk of Kent, is in Mr. Toulmin Smith’s
collection.[625]
[622] _Poly-ptych-odon_; many-wrinkle-tooth.
[623] _Geol. Proc._ vol. iii. p. 449. The bones from Hythe were
presented by their discoverer, H. B. Makeson, Esq., to the British
Museum. See _Petrifactions_, p. 200.
[624] Owen’s Monograph, Cretac. Reptilia, Pal. Soc. p. 47.
[625] Ibid. p. 55. See also Dixon’s Foss. Suss. p. 378. Teeth of the
Polyptychodon are figured in _Odontography_, pl. lxxii.
CHAPTER XVII.
FOSSIL REPTILES; COMPRISING THE DEINOSAURIANS, PTERODACTYLES, TURTLES,
SERPENTS, AND BATRACHIANS.
III. Deinosaurians.--The Order Deinosauria (_fearfully-great lizards_)
has been established for the reception of those extinct colossal
reptiles, comprising the _Megalosaurus_, _Hylæosaurus_, _Iguanodon_,
and _Pelorosaurus_, which, in their organization, present the
transition from the Crocodilians to the Lacertians, and whose essential
osteological characters Professor Owen has described as follow:--
"This group, which includes at least three well-established genera
of Saurians, is characterized by a large sacrum, composed of five
anchylosed vertebræ of unusual construction; by the height, breadth,
and outward sculpture of the neural arch of the dorsal vertebræ; by
the two-fold articulation of the ribs to the vertebra:, viz. at the
anterior part of the spine by a head and tubercle, and along the rest
of the trunk by a tubercle attached to the transverse process only;
by broad, and sometimes complicated, coracoids, and long and slender
clavicles; whereby Crocodilian characters of the vertebral column
are combined with a Lacertian type of the pectoral arch. The dental
organs also exhibit the same transitional or annectent characters,
in a greater or lesser degree. The bones of the extremities are of
large proportional size for Saurians; they are provided with large
medullary cavities, and with well developed and unusual processes, and
are terminated by metacarpal, metatarsal, and phalangeal bones, which,
with the exception of the ungual phalanges, more or less resemble
those of the heavy pachydermal Mammals, and attest, with the hollow
long-bones, the terrestrial habits of the species.
"The combinations of such characters, some, as the sacral ones,
altogether peculiar among Reptiles, others borrowed, as it were, from
groups now distinct from each other, and all manifested by creatures
far surpassing in size the largest of existing reptiles, will, it is
presumed, be deemed sufficient ground for establishing a distinct
tribe or sub-order of Saurian Reptiles, for which I would propose the
name of Dinosauria.
"Of this tribe the principal and best established genera are
the _Megalosaurus_, the _Hylæosaurus_, and the _Iguanodon_; the
gigantic Crocodile-lizards of the dry land; the peculiarities of
the osteological structure of which distinguish them as clearly
from the modern terrestrial and amphibious Sauria, as the opposite
modifications for an aquatic life characterize the extinct
_Enaliosauria_, or Marine Lizards."[626]
[626] Brit. Assoc. Rep. 1841, p. 103.
The elaborate investigation of the fossil remains of these stupendous
beings, and the luminous exposition of their organization and
physiological relations, embodied in the report to which the above
extract is introductory, are among the most important contributions
to Palæontology, and afford a striking example of the successful
application of profound anatomical knowledge to the elucidation of the
most marvellous epoch in the earth’s physical history, the _Age of
Reptiles_.
From the great size of the bones of these reptiles, their remains have
excited the curiosity even of the common observer; and although an
exaggerated idea has been generally entertained of the magnitude of the
original animals, yet, even when reduced to their natural proportions
by the rigorous formula of the anatomist, applied to the accumulated
relics which years of laborious research have exhumed from their
rocky sepulchres and deposited in our museums, their dimensions are
sufficiently stupendous to satisfy the most enthusiastic lover of the
marvellous.
Let the reader visit the British Museum,[627] and after examining the
largest thigh-bone of the Iguanodon, repair to the zoological gallery,
and inspect the recent Crocodilian reptiles, some twenty-five or
thirty feet in length; and observe that the fossil _bone_ equals, if
not surpasses, in size, the entire _thigh_ of the largest of existing
reptiles; then let him imagine this bone clothed with proportionate
muscles and integuments, and reflect upon the enormous trunk which
such limbs must have been destined to move and to sustain--and he will
obtain a just notion of the appalling magnitude of the lizards which
inhabited the country of the Iguanodon.
[627] See Fossils of the British Museum, p. 227.
The general characters of the extinct reptiles comprised in the order
_Deinosauria_[628] must be known to the intelligent reader, from the
various popular notices which have from time to time appeared; and
their names have become as familiar as household words. I shall here
restrict myself to a few general remarks on the form and structure of
the teeth, and of some of the more important bones of the best known
species of these great reptiles.[629]
[628] In the new edition of Pictet’s _Paléontologie_ (now in course of
publication), two 4to. plates (xxiii. and xxiv.) are devoted to the
illustration of the remains of these colossal reptiles.
[629] For further account of the Iguanodon, see _Petrif._ p. 224, &c.;
of the Hylæosaurus, _ibid._ p. 314, &c.; of the Pelorosaurus, _ibid._
p. 330, &c.; of the Regnosaurus, _ibid._ p. 333, &c.; and of the
Megalosaurus, _ibid._ p. 328, &c.
[Illustration: Lign. 218. Megalosaurus Bucklandi. 1/4 _nat._
_Great Oolite._ _Stonesfield, Oxfordshire._
Portion of the left ramus of the lower jaw, containing several teeth in
different stages of growth: inner aspect.
_a, a._ Crowns of successional teeth.
_b, b._ Transverse partitions of the tooth-sockets.
]
[Illustration: Lign. 219.
Tooth of the Megalosaurus Bucklandi.
(_Nat. size._)
_Wealden._ _Tilgate Forest._]
[Sidenote: MEGALOSAURUS.]
Megalosaurus (_gigantic lizard_) Bucklandi. _Lign._ 218 and 219. _Bd._
pl. xxiii. _Wond._ p 421.--The oolitic flag-stone of Stonesfield, in
Oxfordshire, has long been celebrated for the bones and teeth of a
gigantic reptile, which Dr. Buckland first described by the name of
_Megalosaurus_, in a highly interesting memoir (_Trans. Geol. Soc._
_sec. ser._ vol. i.), illustrated by figures of the teeth in a portion
of the lower jaw, the sacrum, femur, and other bones. The remains of
this reptile are also frequently discovered in the Wealden (see _Foss.
Til. For._ p. 67, pl. ix. figs. 2, 6). The most important relic of this
great carnivorous terrestrial lizard is a portion of the right ramus of
the lower jaw, containing one perfect tooth, and the germs of several
teeth (_Lign. 218_). The tooth of the Megalosaurus, (_Lign. 219_, and
_Pl. VI. fig. 7_,) has a conical, laterally compressed crown, with
the point recurved like a sabre, and the edges trenchant and finely
serrated. The implantation of the teeth is very peculiar, and exhibits
the dentition of the Crocodilians blended with that of the Lacertians.
The jaw has an outer parapet, as in the true lizards (see _Lign. 205_),
but the teeth are fixed in distinct sockets, formed by transverse
partitions, that are attached to a mesial (_inner_) parapet, composed
of a series of triangular osseous plates; the bases of the old teeth,
and the germs of the new ones, being thus enclosed and concealed.
The tooth is formed of a central body of dentine, the crown having a
coating enamel; and the whole an external investment of cement, which
forms a thicker layer around the fang; the pulp-cavity is occupied by
coarse bone, in the adult tooth. The microscopical examination shows
the dentine to consist of very fine calcigerous tubes, 1/28000th of an
inch in diameter, without any admixture of medullary canals, radiating
from the pulp-cavity at right angles with the external surface of the
tooth, and sending; off numerous secondary branches; these ultimately
dilate into, or inosculate with, a stratum of calcigerous cells
that separates the dentine from the enamel.[630] A thin slice of a
vertical section, viewed by transmitted light, is represented _Pl. VI.
fig. 7 b_; showing the calcigerous tubes radiating from the centre,
and terminating in the stratum of cells; this cellular structure is
invested with a layer of enamel, and the latter with an external coat
of cement, indicated by the dark outline.[631]
[630] Owen’s _Odontography_, p. 271, which should be consulted for more
minute details.
[631] To fully comprehend the minute structure of these and the other
teeth figured in _Pl. VI._ Professor Owen’s plates should be examined;
the small scale necessarily adopted in the present work rendering it
impossible to do justice to the subject.
Four specimens of the sacrum, composed of five anchylosed vertebral
(_Foss. Til. For._ pl. xix. _fig._ 12), have been discovered; one of
these is from Tilgate Forest. The femur of the Megalosaurus has two
large rounded trochanters of nearly equal size, below the head of the
bone; its shaft is sub-cylindrical, and slightly bowed.
This colossal carnivorous Saurian, whose length is estimated at thirty
feet, appears to have been terrestrial, and an inhabitant of the same
_terra incognita_ as the Iguanodon; it probably preyed on the smaller
reptiles, and the young of the Iguanodon, Crocodilians, &c.
Hylæosaurus (_Wealden lizard_) Owenii. _Wond._ pl. iv. and p. 435;
_Geol. S. E._ pl. v.--In the summer of 1832, I obtained the interesting
specimen which first demonstrated the existence of the remains of
another extraordinary modification of Saurian organization in the
Wealden. The circumstances which led to this discovery afford an
instructive lesson to the young collector.
Upon visiting a quarry in Tilgate Forest, which had yielded many
organic remains, I perceived in some fragments of a large mass of
stone, which had recently been broken up and thrown on the road-side,
traces of numerous pieces of bone. I therefore collected all the
recognisable portions of the block, and had them conveyed to my
residence. The first step was to cement together those pieces that
would admit of juxtaposition, and these were at length united into a
block of stone five feet long, three wide, and about one foot thick.
This was firmly fixed in a stout frame, to prevent the separation of
the united portions during the process of chiselling. Guided by the
indications which the sections visible on the edge afforded, a thin
iron wedge was carefully driven in, about half an inch above the
uppermost layer of bones, and a large slab was flaked off; the three
dermal spines (_Wond._ pl. iv. 5) in the middle of the specimen were
thus exposed, and shivered to pieces; some fragments adhered to the
mass broken off, others to the block, and many were detached; every
piece, however small, was collected, and those adhering to the slab
were chiselled out; and the whole were then carefully replaced and
cemented to the bones that remained imbedded in the large block.
After an interval of some days, to allow of the firm cohesion of the
cemented parts, the task was resumed, and the stone chiselled away,
until some portion of the large bones of the pectoral arch (_Wond._
pl. iv. 7) were observed. The specimen was at length brought to the
state in which it now appears (in the British Museum[632]); but
during the progress of its development, which occupied many weeks,
it was repeatedly necessary to suspend the work, and unite displaced
fragments of bone, and resume the task after their consolidation. The
plate in the _Geol. S. E._ conveys a good idea of the original.
[632] See _Fossils, Brit. Mus._ p. 139, &c.
The specimen consists of a part of the spinal column, composed of seven
dorsal and three or four cervical vertebræ, almost in their natural
juxtaposition, with obscure indications of a part of the base of the
skull; eleven ribs; the bones of the pectoral arch (two _coracoids_
and two _scapulæ_); with numerous dermal bones and spines. A second
specimen of this reptile was found near Bolney, in Sussex; and like
the former, it was, unfortunately, almost wholly destroyed by the
labourers; but I obtained many bones, some of which are perfect, and
indicate an animal of considerable magnitude: a _scapula_, nineteen
inches long, an arm-bone or _humerus_, numerous ribs, bones of the
phalanges, &c. A fine series of twenty-six caudal vertebra, having
a total length of nearly six feet, with chevron bones and dermal
spines, was discovered in 1837, in Tilgate Forest.[633] A few detached
bones are the only other relics of this reptile that have come under
my observation.[634] The osteological characters presented by these
remains afford another example of tire blending of the Crocodilian with
the Lacertian type of structure; for we have in the pectoral arch the
scapula or omoplate of a crocodile associated with the coracoid of a
lizard. Another remarkable feature in these fossils is the presence of
the large angular bones or spines (described p. 660, figured _Lign.
208_), which, there is reason to infer, constituted a serrated crest
along the middle of the back: and the numerous small oval dermal bones,
which appear to have been arranged in longitudinal series along each
side of the dorsal fringe. (_Geol. S. E._ p. 323.)
[633] See _Fossils, Brit. Mus._ p. 323.
[634] See "Memoir on the Remains of the Iguanodon, Hylæosaurus, and
other Saurian Reptiles," by the Author, in _Philosophical Transactions_
for 1841, Part II.
The vertebræ, ribs, and other parts of the skeleton found in
these specimens also present modifications of structure of great
interest.[635] No specimens of teeth have been found associated with
the remains of the Hylæosaurus, in such manner as to afford unequivocal
proof of their belonging to that animal. But in the same quarries,
teeth, decidedly of the Lacertian structure, are occasionally found,
and may with some probability be referred to that reptile. These teeth
(see _Pl. VI. fig. 6^a_.) are about 1-1/4 inch in length, and commence
at the base with a cylindrical shank, which gradually enlarges into a
crown of an obtuse lanceolate form, convex in front, hollowed behind,
and terminating in a rounded obtusely angular apex, the margins of
which are generally more or less worn.[636] The crown is solid, but
the fang encloses a small pulp-cavity; the surface is enamelled, and
covered with very fine longitudinal striæ; the base in every specimen
appears broken transversely, as if it had been anchylosed to the jaw,
or to the base of a socket. The fang never presents an appearance of
lateral adhesion, as if belonging to a Pleurodont lizard. Sections of
these teeth expose a simple, central, medullary canal, the upper part
of which is generally filled with the ossified remains of the pulp; and
this is surrounded by a body of firm dentine, with extremely minute
calcigerous tubes radiating from the centre to the periphery of the
tooth, which is invested with a relatively thick coat of enamel, in
which no structure is apparent. _Pl. VI. fig. 6^b_ represents a small
portion of a vertical slice, highly magnified and viewed by transmitted
light. The reference of these dental organs to the Hylæosaurus must
not, however, be considered as conclusive, until confirmed by the
discovery of the teeth attached to the jaw, in connexion with other
parts of the skeleton. The locomotive organs of the Hylæosaurus are
but imperfectly known; a perfect humerus, one phalangeal bone, and
fragments of the fibula (the small bone of the leg) are the only bones
hitherto observed. The length of this reptile, which was probably
terrestrial and herbivorous, may be estimated at from twenty to thirty
feet.
[635] See Report, Brit. Assoc. 1841, pp. 111-120. Phil. Trans. 1841,
pp. 141-144, pl. x.
[636] Rep. Brit. Assoc. 1841, p. 118. Geol. S. E. England, pl. ii.
figs. 2, 4. Phil. Trans. 1841, p. 144, pl. vi. figs. 9, 10, 11.
Iguanodon. _Ligns._ 219 to 226; _Wond._ pl. ii. iii., and pp. 422,
&c.--Soon after my first discovery of the remains of vertebrated
animals in the strata of Tilgate Forest, some teeth of a very
remarkable character particularly engaged my attention, from their
dissimilarity to any that had previously come under my notice.[637]
Attention having been directed to these interesting fossils, examples
were soon discovered of teeth in various conditions, from the sharp,
unused tooth of the young reptile, to the obtuse, worn-out crown of the
adult. From the resemblance of the perfect teeth to those of the Iguana
(_Lign. 205_, p. 649), a land lizard of the West Indies, I proposed the
name of _Iguanodon_ (signifying an animal with teeth like those of the
Iguana) for the extinct reptile to which they belonged. The numerous
bones and teeth subsequently exhumed from the strata of Tilgate Forest
and other localities in the Wealden of Sussex and of the Isle of
Wight, and the considerable portion of the skeleton of an individual
discovered by Mr. Bensted in the Kentish Rag, have supplied the data
upon which our present knowledge of the characters of the original is
based.
[637] These are described in _Foss. South D._ 1822, p. 54, under the
head "_Teeth and bones of unknown animals_." This was the earliest
published notice of the fossils of the Wealden; it contains also a
description of a tooth of the Megalosaurus (p. 55, No. 42).
In Wond, pp. 422-435, a brief account will be found of the character
of the teeth, horn, femur, vertebræ, &c., and of the Maidstone
specimen[638] (_Pl. III._).
[638] In a Monograph on the Reptiles of the Cretaceous Deposits of
England, published by the Palæontographical Society, Professor Owen has
lately figured anew and described in detail this most valuable fossil
skeleton; to which description are appended the Professor’s latest
views on the structure of the teeth of this reptile.
The "Geology of the South-east of England" contains accurate figures
of the long bones of the leg (_Geol. S. E._ pl. ii), femur, clavicles
(_Geol. S. E._ pl. iv.), tympanic bone (_Geol. S. E._ pl. ii.), horn
and ungual bone (_Geol. S. E._ pl. iii.). In the "Fossils of Tilgate
Forest," there are fifteen quarto plates devoted to the illustration of
the bones and teeth of the Iguanodon and other Wealden reptiles. The
osteological structure is fully detailed in _Rep. Brit. Assoc._ 1841,
pp. 120-144. A general notice of the principal bones of the Iguanodon,
with plates, will be found in _Phil. Trans._ 1841, pp. 131-151; and in
_Petrif._ chap. iii. the author has given a detailed account of the
most important specimens, both in the British Museum and in his own
collection, together with a résumé of the palæontology and geology of
the Wealden district.
[Illustration: Lign. 220. Iguanodon Mantelli. 1/7 _nat. size_.
_Wealden._ _Tilgate Forest._
The right ramus of the Dower Jaw; [639] discovered in 1848, by Captain
Lambart Brickenden, F.G.S.]
Fig. 1.--The inner aspect, showing three teeth, and the sockets of
eighteen.
_a._ Germ of a tooth.
_b._ Perfect crown of a successional tooth.
_c._ Remains of a successional tooth, the upper part having
been broken off.
_d._ The symphysial extremity of the jaw.
_e._ The opercular furrow.
_f._ The coronoid process.
2, 3, and 4, the teeth _a_, _b_, and _c_, in _fig._ 1, represented
on a larger scale.
[639] For the outer aspect, and a restoration of the whole jaw,
_Petrif._ pp. 247 and 249.
[Illustration: Lign. 221. Lower Tooth of the Iguanodon: _nat. size_.
_Wealden._
_Tilgate Forest._
The apex slightly worn.
Fig. 1.--Inner aspect, showing the longitudinal ridges, and denticulated
margins of the crown of the tooth.
2.--View of the outer surface of the tooth.
_a._ The denticulated margin.
_b._ The apex of the crown, worn by use; b. _fig._ 2, shows the
oblique smooth surface produced by mastication.
_c._ A transverse fracture of the fang, showing a section of
the medullary cavity occupied by the ossified remains of
the pulp.
_d._ Marks the inferior limit of the denticulated margin; if a
line were carried horizontally from d, across the tooth, the
under figure would represent a tooth worn flown below the
denticulations, and deprived of its peculiar dental
characters; in this latter state the tooth somewhat resembles
an incisor of a Rhinoceros (see _Ligns. 222, 223_; and
_Petrif._ _Lign. 48_).
]
[Illustration: Lign. 222. Upper Tooth of the Iguanodon: _nat. size_.
_Wealden._ _Brook Bay, Isle of Wight._
The crown is worn down to an oblique smooth surface, and the fang is
absorbed.]
Jaw and Teeth of the Iguanodon. _Ligns. 219-223._--Although the form
and structure of the cranium are unknown, yet the half of a lower jaw,
discovered in Sussex by Capt. L. Brickenden,[640] and a fragment of an
upper jaw, found some years since,[641] enable us to form a tolerably
perfect idea of the structure and functions of the dental organs of
the Iguanodon. The unused tooth of this reptile is characterized by
the prismatic form of the crown, the presence of from two to four
longitudinal ridges on its enamelled face, the denticulated margins
(_Lign. 221, a_), and finely serrated edge of the summit, as seen in
_Lign. 220, fig. 3_. The shank or fang of the tooth (_Ligns. 221,
223, fig. 2_) is sub-cylindrical, slightly curved, and tapers to a
point. The inner surface of the crown in the lower teeth, and the outer
surface in the upper, are covered with a thick layer of enamel, but the
opposite face of the crown and the sides have but a thin coating of
this substance. The teeth of the upper jaw (_Lign. 222_) are curved in
the opposite direction to those of the lower, and have the convexity
external, and the concavity internal. Thus the upper and lower molars
were related to each other nearly as in the Ruminants; the outer aspect
below corresponding to the inner above (see _Petrif._ _Lign._ 56, p.
254). The specimens met with have almost always the apex of the crown
more or less worn down by use[642] (see _Lign. 223_), and presenting
an oblique, triangular, smooth surface, as in the fine large specimen
figured in _Lign. 221_, which was found imbedded in the trunk of a
Clathraria, as if it had snapped off while the animal was in the act of
gnawing the tough stem. The denticulated margins are well developed;
in _fig. 1_, they appear as simple serrations; but viewed laterally,
they are seen to be formed by a series of denticulated plates (_Lign.
223, fig. 6_). The crown of a tooth of a young animal, worn at the
summit, and presenting but three longitudinal ridges, is represented
_Pl. VI. fig. 4^a_. The microscropical structure consists of a simple
pulp-cavity in the centre of a body of dentine permeated by calcigerous
tubes, but with this peculiar modification, that the dentine is
traversed by vascular canals, radiating at definite intervals from
the pulp-cavity nearly to the periphery of the tooth, and running
parallel with the calcigerous tubes; thus constituting a softer and
coarser dentine than in the other reptiles, and resembling that which
characterizes the teeth of some of the herbivorous mammals.[643] The
crown of the tooth is covered with a layer of enamel, which is thickest
on the external surface: and the fang is invested with cement. The
structure here described is shown in _Pl. VI.; fig. 4^b_, a vertical,
and _fig. 4^c_, a transverse section of a tooth, seen by transmitted
light, with a high magnifying power. The calcigerous tubes are 1/25000
an inch in diameter. Sections of the teeth of the Iguanodon are
beautiful objects under the microscope, for the medullary canals are
generally of a deep yellowish brown colour.
[640] Figured and described in the _Phil. Trans._ 1848, p. 188, pl.
xvi. xvii.
[641] Both specimens are fully described in _Petrif._ pp. 242, _et seq._
[642] Plates iv. and xvii. in the "Fossils of Tilgate Forest," contain
representations of upwards of thirty specimens of teeth in various
states of development and detrition.
[643] Tomes on the Microscopic Structure of the Tooth of the Iguanodon,
_Petrif._ pp. 239, 240. See also Owen’s _Odontography_, p. 249, and pl.
lxxi.; and _Cycl. Anat._ Art. Teeth.
[Illustration: Lign. 223. Teeth of Iguanodon. _Wealden._ _Tilgate
Forest._]
Fig. 1.--Outer aspect of an upper tooth (in a reversed position), worn
flat, and with the fang absorbed; fig. 3, inner aspect of the
same tooth.
_a, a._ Flat grinding surface, produced by mastication when all
the thickly enamelled portion of the crown is worn away.
_c._ Cavity produced by the pressure of a new tooth.
2.--Lower tooth of a young animal, slightly worn: inner aspect.
4.--Outer Surface of a lower tooth of an adult; and fig. 5, inner
surface of the same.
_a, a._ The hard cutting edge of the oblique surface worn by
mastication.
_c._ Indentation produced by the pressure of a successional
tooth.
6.--Edge view of the serration on fig. 5; magnified.
The dentine is less vascular, and therefore hardest, on that side of
the crown which has the thicker coat of enamel; hence the tooth wears
away faster on one side than on the other, and an oblique grinding
surface, with a sharp edge of enamel, is maintained until the crown
is worn away. The internal structure of the teeth of the Iguanodon is
thus in perfect accordance with their external configuration, and must
have been admirably adapted, in every stage, for the laceration and
comminution of the tough vegetable substances which, there is every
reason to conclude, constituted the food of this colossal oviparous
quadruped.
Vertebra of the Iguanodon,[644] _Lign. 206_, p. 653; _Lign. 224_.--The
remains of the vertebral column of the Iguanodon, consisting generally
of broken and water-worn dorsal and caudal vertebræ, deprived of their
processes and reduced to the state of the specimens represented _Lign.
206_, _figs._ 6 and 8, are so abundant in some of the Wealden strata,
that a short account of their characters may be useful. A reference to
_Lign. 206_, and its description, will render the following remarks
intelligible to the general reader. The vertebræ of the Iguanodon are
distinguishable from those of other reptiles which occur in the same
strata by the following peculiarities, which the figure of a perfect
specimen of a caudal vertebra (_Lign. 206, fig 3_) will serve to
illustrate. The body, or centrum, is either flat or somewhat depressed
on both articular faces; its sides are nearly flat, or somewhat convex,
vertically (as in _fig 3_), and slightly concave lengthwise, or from
front to back: in some examples, the body is more contracted towards
the inferior surface, as in _fig. 6_; and in the vertebræ, near the
middle of the tail, the sides are compressed, so as to give an angular
contour and somewhat vertical elongation to the face, as in _fig. 4_;
but in the dorsal vertebræ, the articular faces are nearly circular,
but somewhat higher than wide. In the caudal vertebræ, the inferior
angles of the body are truncated (_w, figs. 3, 4_), and present an
oblique, smooth face, to articulate with the chevron bone (_fig. 3,
f_). The annular part is united to the body by suture (_fig. 3,
o_), and anchylosed in the dorsal vertebræ; and in these bones the
neural arch is very high, and greatly expanded, and its bases extend
transversely inwards, and join each other below the spinal canal,
forming a ring, or bony channel, to contain the spinal chord.[645]
"The transverse processes are straight, and very long in the vertebræ
from the middle of the trunk, indicating a considerable expanse of the
abdominal cavity, adapted for the lodgment of the capacious viscera
of a herbivorous quadruped." (_Owen._) The spinous processes (_Lign.
206, fig. 3, d_) are large and of great height in the anterior
caudal vertebræ, _Lign. 224_; and here the chevrons, or hæmapophyses
(_Lign. 224, b_, and _Lign. 206_, _fig. 2_, and _fig. 3, f_), are
also of considerable length; the bases of the latter are always united
(_Lign. 206, fig. 2, g_), and often blended, so as to form but one
face for articulation with the truncated inferior angles of the body of
the vertebra:, leaving a vertically elongated channel for the passage
of the large blood-vessels of the tail. The external surface of the
vertebræ of the Iguanodon is more or less marked with fine longitudinal
striæ; those of the Megalosaurus have a smoother and more polished
surface.[646]
[644] A detailed account of the elements of the spinal column of the
Iguanodon, and remarks on various fossil vertebræ, the relations of
which with the Iguanodon have been considered doubtful, will be found
in _Petrif._ pp. 256-279.
[645] See also lithographs of dorsal and caudal vertebræ from the
Kentish Rag; Owen’s _Monog. Cret. Rept._ (Pal. Soc.) 1851.
[646] See Rep. Brit Assoc. 1841, pp. 125-133, where an elaborate
investigation of the vertebra: of the Iguanodon is given by Professor
Owen.
[Illustration: Lign. 224. Six Caudal Vertebra of the Iguanodon. 1/14
_nat. size_.
_Wealden._ _Tilgate Forest._
_a, a._ Spinous processes (_neurapophyses_), from 13 to 15-1/2 inches
in height.
_b, b._ Three displaced chevron bones (_hæmapophyses_), imbedded
in the stone near their original position at the junction
of the bodies of the vertebræ.
_c._ Anterior articular face of a vertebra.
]
Bones of the Extremities. _Ligns._ 225 and 226.--The thigh-bone
(_femur_), both bones of the leg (_tibia_ and _fibula_), and many of
the metatarsal and phalangeal bones have been discovered; the osteology
of the hinder extremity is, therefore, almost perfect. The thigh-bone
(_Lign. 225_; and _Petrif._ p. 292,) is of a very remarkable character,
having a closer resemblance to the femur of a huge mammalian, than to
that of a reptile.[647] Several perfect specimens have been discovered,
as well as the associated bones of the leg (_Petrif._ p. 293, _Lign._
62); but the first fragment that came under my notice, was the
middle portion of the shaft of a femur of enormous size, and of an
irregular quadrangular form; and so shapeless and unintelligible it
then appeared, that several years elapsed before its real nature was
determined. (_Foss. Tilg. For._ pl. xviii.)
[647] See Cuvier’s _Ossem. Foss._ vol. ii. p. 36.
An entire thigh-bone of an adult Iguanodon, from the Weald clay in the
west of Sussex, measured three feet eight inches in length.[648] end
thirty-five inches in circumference at the condyles; and I have a femur
of a very young animal, that is but five inches long. The form of the
thigh-bone is so peculiar, that fragments may easily be recognised. The
head of the femur (_Lign. 225, f_,) is hemispherical, and projects
inwards; there is no appearance of a _ligamentum teres_; a flattened
process or trochanter (_Lign. 225, a_,) forms the external boundary
of the neck of the bone, from which it is separated by a deep and
narrow vertical fissure; the shaft is of a sub-quadrangular shape, and
a slightly elevated ridge, produced by the union of two broad, flat,
longitudinal surfaces, extends down the middle of the anterior face,
and, diverging towards the inner condyle, gradually disappears. The
bone terminates below in two large condyles, separated in front and
behind by a deep, narrow cleft, or groove (_Lign. 225, e_). Near the
middle of the inner edge of the shaft, there is a compressed ridge,
with an angular projection, or trochanter. Thus the upper part of
the femur maybe known by the presence of the flattened, or laterally
compressed trochanter; and if that process be wanting, a fractured
surface indicating its position may be detected; the middle of the
shaft is characterized by its broad angular faces, and the inner
submedian trochanter: the condyloid or inferior extremity of the bone
may be distinguished by the deep groove between the condyles, both in
front and behind.
[648] The average length of the adult femur is estimated at about four
feet five inches.
[Illustration: Lign. 225. Left Femur of the Iguanodon. 1/10 _nat. size_.
Anterior aspect.
_Wealden._ _Brook Bay, Isle of Wight._
_a._ Outer trochanter.
_b._ Median trochanter.
_c._ Inner condyle.
_d._ Outer condyle.
_e._ Anterior infra-condyloid fissure.
_f._ Head of the femur.
]
The arm-bone (_humerus_) of the Iguanodon has been discovered in the
Wealden of the Isle of Wight by Mr. Fowlstone; it is figured and
described in _Petrif._ p. 286. The humerus is also present in the
Maidstone specimen[649] of Iguanodon, before referred to at page 692:
in pl. ii. of _Wond._ this bone is termed the _radius_. The humerus of
this reptile is much smaller than the femur; in the Maidstone specimen
the former is about 20 inches, and the latter about 33 inches in length.
[649] The two bones marked "6" in pl. ii. _Wond._ and in _Lign._ 65,
_Petrif._ (one of which is figured in outline in _Lign. 226, fig.
4_,) regarded by Prof. Owen as the _radius_ and _ulna_ (the two bones
of the fore-arm): the author’s reasons for regarding these bones as
_metacarpals_ are given in full at p. 289, _Petrif._
As separate bones of the feet of the Iguanodon, for example,
_metacarpals_, _metatarsals_, _phalangeals_, and _unguals_, often
occur in the strata of the Wealden, figures of several specimens, on
a reduced scale, are introduced in _Lign. 226_, and may enable the
student to identify those he may meet with in his researches.[650] The
ungual phalanges, or claw-bones, which were invested with the nail, are
sometimes found of an enormous size; from a quarry near Horsham, Mr.
Holmes obtained specimens more than five inches long, and three inches
wide at the articular extremity.
[650] See Rep. Brit. Assoc. 1841, pp. 137-142.
Length of the Iguanodon.--The length of the united head and trunk,
according to my estimate in _Geol. S. E._ p. 316, is seventeen feet
and a half; by Professor Owen’s estimate it is reduced to fifteen
feet;[651] a difference of no importance in such merely approximative
calculations, particularly when the form of the cranium is unknown.[652]
[651] Ibid. p. 144.
[652] The more recently discovered specimen of lower-jaw, already
referred to, page 693, indicates a length of between three and four
feet for the entire jaw, _Petrif._ p. 249.
[Illustration: Lign. 226. Bones of the Feet and Claws of the Iguanodon.
_Wealden._ _Tilgate Forest._
(See _Wond._ pl. in.)
Fig. 1.--Metatarsal: original 6 inches long: upper surface.
2.--Metacarpal bone.
3.--Under surface of fig. 1.
4.--A phalangeal bone of the fore-foot: the original 14 inches long.
4_a_.--A transverse section of the same, showing the medullary
cavity.
5.--One of the second row of phalangeal bones of the fore-foot.
6.--View from above of one of the claw-bones of the hind-foot;
1/6 _nat._
7.--Profile of claw-bone of fore-foot:[653] 1/6 _nat._
8.--Metatarsal, or bone of the hind-foot: 1/8 _nat._
_a._ Denotes the proximal articulation, or that nearest the
trunk.
_b._ The distal, or extremity most distant from the trunk.
]
[653] This bone is conjecturally referred by Prof. Owen to the
Megalosaurus.
The estimated extent of the tail has been subject to variation. My
early estimate of its length gave rise to the idea of this reptile
having attained seventy feet in length. Professor Owen, however,
considered that the abbreviated character of the anterior caudal
vertebræ indicated a far less extent of tail, which the Professor
estimated at thirteen feet; this opinion, from the evidence then before
us, seemed well founded, but from evidence since afforded by a series
of eleven caudal vertebra, belonging to the middle region of the tail,
that have been lately discovered, (_Petrif._ p. 312,) it is not at all
improbable, that, instead of all the caudal vertebræ being abbreviated,
these elements of the tail were elongated as in the corresponding part
of the skeleton of the Iguana, and that the largest Iguanodons may have
attained a length of from sixty to seventy feet.
The author’s physiological inferences as to the structure and economy
of the Iguanodon, deduced from the study of the osseous remains of this
singular creature, especially the lately discovered remains of the
jaw-bones, are given in full at pp. 307-313 _Petrif._ or _Foss. Brit.
Mus._: and at pp. 335-338, _ibid._ may be found some general remarks
on the physical geography and the nature of the fauna and flora of the
country inhabited by these stupendous reptiles, whose remains are so
characteristic of the Wealden rocks.
Jaw of the Regnosaurus. (_Petrif._ p. 333.)--A portion of the right
ramus, or side, of the lower jaw of this reptile was discovered
in a block of sandstone from Tilgate Forest. It consists of a
fragment, six inches long, of the dentary bones, with a small
portion of the opercular; and it contains the fangs of fifteen
teeth, which are closely and evenly set in a regular series, and
imbedded laterally in grooves, or sockets, in the dentary bone;
there are three or four sockets of successional teeth on the inner
side of the bases of the old teeth. (_Phil. Trans._ 1841, pl.
v. figs. 1, 2.) Unfortunately, all the crowns of the teeth are
wanting. The outer parapet of the dentary piece is entire, and its
upper margin is finely crenated. All the fangs of the teeth are
exposed, but there are traces of a thin inner wall, indicating the
probability that, as in the Megalosaurus, the teeth were supported
medially by an osseous plate, and were implanted in distinct
sockets.[654] In my memoir on this fossil jaw in the _Phil.
Trans._ (1841, p. 131), I referred it to the genus Iguanodon;
but subsequent observations have led me to conclude that it is
generically distinct; and in my Memoir on the Jaw of the Iguanodon,
in _Phil. Trans._ 1848 (p. 183), I have proposed for the animal to
which it belonged the distinct generic appellation, Regnosaurus,
with the specific name _Northamptoni_.
[654] The collector will perceive the importance that attaches to
the discovery of even a fragment of the jaw of an unknown reptile,
containing teeth in their natural position.
[Sidenote: LACERTIAN REPTILES.]
IV. Lacertian Reptiles.--The recent Lacertians, or true Lizards, are
smaller and less highly organized reptiles than the Saurians of the
Crocodilian order; and their dermal covering consists of a finer and
more delicate squamous integument. They are also characterized by
important modification in their osteological structure. The spinal
column is almost always composed of concavo-convex vertebræ, with the
convexity behind; the ribs are slender and rounded, having a single
convex tubercle of attachment. The fossil species are, for the most
part, of gigantic dimensions, and deviate in a striking manner from any
that now exist. Vertebræ of the recent lacertian type are very rare in
the secondary strata; I believe a few in my cabinet, obtained from the
sandstone of Tilgate Forest, and which belonged to a very small unknown
reptile, are the most ancient examples at present known.
[Illustration: Lign. 227. Mosasaurus Hoffmanni.
(_The original is feet by 2-1/2 feet._)
Remains of the jaws of the great fossil reptile of Maestricht.]
Mosasaurus. _Bd._ pl. xx.; _Wond._ p. 311; _Petrif._ p. 193.--Of the
fossil lizard of Maestricht, named _Mosasaurus_ (lizard of the Meuse)
from the river adjacent to the quarries of St. Peter’s Mountain,
in which its remains have been discovered, I have given a detailed
account at pages 193-196 of _Petrif._ A specimen, with the jaws, and
bones of the palate armed with teeth, now in the museum at Paris, has
long been celebrated, and is still the most precious relic of this
extinct reptile hitherto discovered; a reduced representation is given
in _Lign. 227_; and _Pict. Atlas_, pl. lxx. This is the _Mosasaurus
Hoffmanni_.[655] The specimen is four and a half feet long, and two
and a half feet wide; it consists of both sides of the lower jaw, with
the right ramus of the upper jaw in its natural position, and the
left, which is displaced, lying across the articular extremity of the
left branch of the lower jaw: of the pterygoid bones, which are armed
with teeth; of the left tympanic bone (_os quadratum_), which is but
little removed from its natural situation, and connects the lower jaw
with the cranium; one of the metacarpal or metatarsal bones, and some
fragments.[656]
[655] Several fine portions of the jaws, and many vertebræ of this
animal, are in the British Museum: see _Foss. Brit. Mus._ p. 139. In a
splendid work, _Histoire Naturelle de la Montagne de St. Pierre_, by
the late Faujas St. Fond (1 vol. folio, with numerous plates), there
are admirable figures of the remains of the Mosasaurus.
[656] In the British Museum there is a cast of this specimen, in a case
near the bones of the Iguanodon.
[Illustration: Lign. 228. Mosasauroid Teeth.[657] 1/2 _nat. size_.]
Figs. 1_a_, 2_a_. Transverse sections of the
crowns of the teeth, figs. 1 and 2 respectively.
[657] Reduced from figures accompanying Dr. Gibbes’s Memoir "On
the Mosasaurus and three allied new genera," (with plates,) in the
_Smithsonian Contributions_, vol. ii. 1849. This interesting paper
comprises much information regarding the Mosasaurians of the Cretaceous
deposits of N. America; but we cannot fully coincide with the author in
his palæontological determinations.
The teeth are large, and supported on expanded conical osseous
eminences, which are anchylosed to the alveolar ridge of the jaw
(_acrodont_). The crown of the tooth is conical and recurved, with
the outer face nearly flat, and this space is bordered on each side
by a longitudinal ridge; giving the tooth somewhat of a pyramidal
figure. (See _Ligns._ 228-230.) Professor Owen states that the crown
consists of a body of simple and firm dentine, with fine and close-set
calcigerous tubes, enclosing a simple pulp-cavity; irregular processes
of the latter extend as medullary canals into the conical base of the
tooth, but not, as in the Iguanodon, into the substance of the coronal
dentine; the dentine is invested with a moderately thick coat of
enamel.[658]
[658] See Odontography, p. 258, and pl. lxxii.; the student should also
consult Cyclop. Anat. Phys. _Art._ Teeth.
The vertebræ of the Mosasaur, as is usual in the existing lizards and
crocodiles, are concave in front and convex behind, and the neural
arch is united to the centrum by suture. The entire vertebral column
of _M. Hoffmanni_ appears to have consisted of 131 vertebræ, of which
97 belonged to the tail.[659] This Mosasaur was about twenty-five feet
long.
[659] See Cuvier, _Oss. Foss._ vol. v. pp. 326-334.
[Illustration: Lign. 229. Tooth of Mosasaurus: _magn. twice._
Either a pterygoid tooth of M. Hoffmanni, or a jaw-tooth of M. gracilis.
_Chalk._ _Gravesend._
(In Mr. Wetherell’s Collection.)]
This extinct lacertian reptile forms an intermediate link between
the Saurians without pterygoid teeth (Monitors) and those with them
(Iguanas). Its crocodilian affinities are but partial.
The Mosasaurus appears to have had webbed feet, adapted or crawling on
land as well as for swimming,[660] and a long and vertically expanded
tail, serving as a powerful oar, and enabling the animal to stem the
roughest waters.
[660] See Prof. Owen’s observations on the bones that have been
regarded as referable to the extremities of this creature, and
especially on the phalangeal and other bones of the Mosasaur of the New
Jersey greensand; _Monog. Cret. Rept._ 1851, pp. 36-40.
Prof. Goldfuss has described the remains of another and smaller species
of Mosasaurus (_M. Maximiliani_), from Upper Missouri, U.S.; and Prof.
Owen, in Dixon's "Fossils of Sussex," has established a third and still
smaller species (_M. gracilis_),[661] to which he refers the four or
five mosasaurian vertebræ found in the Chalk of Sussex. Two of these
(caudal) are figured in _Geol. S. E._ p. 146, and _Petrif._ _Lign._ 44;
and these and others are lithographed in plate viii. of Prof. Owen’s
_Monog. Cret. Reptilia_, 1851.
[661] See also _Monograph on the Reptiles of the Chalk_, 1851, p. 31,
and plate ix.
The remains of Mosasaurus occur also in the cretaceous sands of New
Jersey, U. S. (See Dr. Morton’s _Synopsis of the Organic Remains of the
United States_, 1834; and the Quart. Journ. of the Geological Society,
vol. v. 1849.)
Leiodon anceps.[662]--Under this name Professor Owen has described
a splendid fossil, consisting of a portion of the lower jaw of an
acrodont reptile, with teeth, obtained by Edward Charlesworth, Esq.
from the Chalk north of the Thames. This specimen was submitted to my
inspection, many years since, by Mr. Charlesworth, and I then pointed
out the analogy of this acrodont jaw to that of the Mosasaurus.
[662] Ibid. p. 42, pl. ix. A.
Prof. Owen in 1840 (_Odontog._ p. 261), and in 1841 (_Rep. Brit.
Assoc._ p. 144), described and figured some teeth from the same
specimen, which were lent by Mr. Charlesworth. These teeth the
Hunterian Professor regarded as characteristic of a new genus of
Mosasauroid reptile, to which he gave the name _Leiodon_ (in allusion
to the smoothness of the teeth). In 1845 (_Rep. Brit. Assoc._ p. 60)
Mr. Charlesworth noticed, and in 1846 (_London Geol. Journal_, p.
23, plates iv. and vi.) figured and described, the above mentioned
portion of jaw with teeth, under the name _Mosasaurus stenodon_; and
in 1851 Prof. Owen figured and described this specimen under the name
of _Leiodon anceps_, which was originally proposed for the animal, as
known from its teeth, in 1840.
The portion of bone on which the teeth, five in number are implanted
is seven inches in length, and is, in Professor Owen s opinion, the
dentary piece of the lower jaw, and not a portion of a pterygoid bone.
Mr. Charlesworth has had a section made of four of the teeth, and finds
that the pulp-cavities are more or less occupied with solid cones of
silex, which must have permeated the osseous parietes of the teeth.
[Illustration: Lign. 230. Mosasauroid Tooth.
Resembling the back-teeth in the lower jaw of Mosasaurus Hoffmanni.
_Chalk._ _Gravesend._
(In the Collection of Mr. Wetherell.)]
The teeth of Leiodon have a simple pulp-cavity, surrounded by fine
dentine, with an external layer of smooth enamel. The apex of the crown
is sharp-pointed; the body of the crown is slightly recurved; its base
is expanded into a thick circular fang, which is anchylosed to a short
conical process of the alveolar border of the jaw: the teeth differ
from those of the Mosasaurus in having the outer side as convex as the
inner side, the transverse section being an ellipse with pointed ends,
which latter correspond with the lateral trenchant edges of the crown
of the tooth: the teeth are more closely set than in the Mosasaur and
Geosaur. (_Owen._)
Geosaurus Sœmmeringii. _Petrif._ p. 175.--In the British Museum are the
remains of a reptile from the "white Jura" (upper oolite) of Monheim,
in Franconia, which Cuvier describes as being more nearly related to
the Lizards than Crocodiles. The length of this reptile is estimated
at about ten feet. The eyes had a circle of osseous plates in the
_sclerotica_, like those of the Ichthyosaurus; the teeth resemble those
of the Mosasaurus in being sub-compressed and recurved, but they are
at once distinguished by their anterior and posterior finely serrated
sharp edges; the crown is invested with an external coat of enamel.[663]
[663] Oss. Foss. tom. v. p. 343.
Raphiosaurus subulidens.--A portion of a lower jaw, containing
twenty-two closely set, subulate teeth, anchylosed by their bases to
a shallow alveolar groove and an outer alveolar parapet of bone, as
in the Iguana, thus corresponding with the pleurodont Lizards, is
described under this name by Professor Owen, (_Geol. Trans._ 2d ser.
vol. vi. pl. xxxix.); and _Monog. Cret. Rept._ (Pal. Soc.) 1851, p.
19, pl. x. figs. 5, 6. It is from the Lower Chalk, near Cambridge, and
is in the collection of James Carter, Esq. of that place. Remains of
Raphiosaurus have been found also in the Chalk at Northfleet, Kent.
Dolichosaurus longicollis.--In the Chalk of Kent was found, some years
since, a considerable portion of the skeleton of a lacertian reptile,
consisting of the posterior half of the spinal column, with remains of
the pelvic and thigh bones; it was figured in the _Geol. Trans._ 2d
ser. vol. vi. pl. xxxix.; and is now in the collection of Sir P. G.
Egerton. From the researches of the late Mr. Dixon, it appears that a
mutilated reptilian head and anterior portion of a spinal column, with
fore-arm and scapular bones, now in the collection of Mr. Smith, of
Tunbridge Wells, belong to the same skeleton as the vertebral remains
above mentioned. Both specimens were obtained at the same time from
the well-known chalk-pit at Burham, Kent. Professor Owen has lately
described these interesting remains in detail (_Monog. Cret. Rept._
1851, pp. 22, &c.), and finds no intrinsic contradiction to exist
to the historical evidence adduced as to the probability of the two
moieties having belonged to the same individual. In the two specimens
there exist sixty-three concavo-convex (_procœlian_) vertebræ, of which
fifty-seven form the series between the skull and the pelvis, giving
the trunk a length of about eighteen inches. This unique reptile was
elongate and snake-like in its form, with the abdomen deep and narrow,
like that of the water-snakes: its limbs were short; its tail, from
the character of the few caudal vertebræ remaining, must have been
relatively long and powerful. This long and slender lacertian was
therefore probably to a considerable degree aquatic in its habits,
swimming with an undulatory eel-like movement.
The Dolichosaurus (_long-lizard_) presents somewhat of the ophidian
character in the number and size of its cervical vertebræ, in the size
and shape of its ribs, and in the slender proportions of its trunk and
head; but, with these partial exceptions, its affinities are truly
lacertian. (Owen.)
Rhynchosaurus articeps. _Lign. 231._--In a quarry of Upper New Red
Sandstone at Grinsell, near Shrewsbury, Dr. O. Ward discovered a skull
(3-1/2 inches long), vertebræ, ribs, bones of the pectoral and pelvic
arches, portions of two femora with medullary cavities, and fragments
of other bones of a very remarkable lacertian reptile (_Lign. 231_).
The lower jaw is preserved with the skull in its natural position. The
cranium in its general aspect resembles that of a turtle, rather than
of a lizard; for the intermaxillary bones are double, as in Chelonians,
and symmetrical, and are not united by a median process; they are
very long, and curve downwards, giving the fore part of the skull the
profile of a parrot. See _Lign. 231_.
[Illustration: Lign. 231. Rhynchosaurus articeps. _New Red Sandstone;
near Shrewsbury_
Fig. 1.--Lateral view of the cranium and lower jaw: 1/2 _nat size_.
Cranium.
_a, a._ Intermaxillary bones.
_b._ Nasal.
_c._ Frontal.
_d._ Maxillary.
_e._ Anterior frontal.
_f._ Lachrymal.
_g._ Malar.
_h._ Posterior frontal.
_i._ Orbital division of posterior frontal.
_k._ Temporal.
_l._ Tympanic.
Lower Jaw.
_m._ Dentary.
_n._ Coronoid.
_o._ Articular.
_p._ Angular.
_q._ Opercular or splenial.
_r._ The orbit.
Fig. 2.--The upper aspect of a dorsal vertebra: _nat. size_.]
There are no teeth apparent in either jaw: the margin of the upper
maxillary has feeble dentations, but in the lower jaw even these
indications are wanting, and it is probable that this reptile had its
jaws encased by a bony or horny sheath, as in birds and turtles.[664]
(Owen.)
[664] Rep. Brit. Assoc. 1841, p. 150. See also Camb. Phil. Trans, vol.
vii. p. 357, tab. 5, 6.
Thecodontosaurus and Palæosaurus. _Ly._ p. 306, figs. 348,
349.--Numerous bones and teeth of reptiles occur in the Magnesian
Conglomerate, near Bristol, and have been described by Dr. Riley and
Mr. Stutchbury in an interesting memoir to which reference should be
made for details (_Geol. Trans._ 2d ser. vol. v. p. 349, pl. xxix.
xxx.). The bones denote an approach to the lizards; the teeth are
implanted in sockets; these reptiles, therefore, belonged to the group
termed thecodont, and the name _Thecodontosaurus_, given to these
extinct Saurians by Dr. Riley, has reference to this character. The
teeth are pointed, compressed laterally, slightly convex on each side,
with a trenchant, finely serrated edge in front and behind; the fang is
sub-cylindrical. Other teeth from the same deposit, possessing the same
general characters, but distinguished by peculiarities of form, have
been referred to another genus, named _Palæosaurus_. The vertebræ found
associated with the teeth and jaws are biconcave, and are remarkably
characterized by the great depth of the spinal canal in the middle of
the centrum or body of the vertebræ, so that the spinal chord must have
presented a moniliform or bead-like appearance. These reptiles, in
their _thecodont_ type of dentition, biconcave vertebræ, double-headed
ribs, and proportionate size of the bones of the extremities, are
nearly allied to the _Teleosaurus_, (see _ante_, p. 679); but they
combine a lacertian form of tooth, and a lacertian structure of the
pectoral, and probably of the pelvic arches, with these crocodilian
characters; they have also distinctive modifications: such, for
example, as the moniliform spinal chord.[665]
[665] Owen; Rep. Brit. Assoc. 1841, p. 155, &c.
Dicynodon. _Ligns. 232, 233, 234._--This singular fossil reptile was
discovered, by Mr. Bain, in South Africa. It is distinguished, by
some remarkable peculiarities of structure, from other animals of the
Saurian order; of which it represents a new tribe, or sub-order. The
cranium is narrow; the nostrils are divided, as in Lizards, and not
confluent, as in Chelonia; the skull, in other respects, much resembles
in general appearance that of a Turtle; the orbits are large; the
jaws are edentulous, as in the Turtles, with the exception of a pair
of long tusks,[666] implanted in sockets in the upper maxillary bone,
like those of the Walrus; these tusks are of a finer texture than
that of the Crocodile’s teeth, and almost as dense as in the Hyæna.
These creatures present in the most striking manner that blending of
the peculiarities of several existing orders, which is continually
presented to the palæontologist; for with a type essentially lacertian
are combined crocodilian and chelonian modifications. Although no
vestiges of these reptiles have been discovered in England or in
Europe, yet the occurrence of an allied form, the _Rhynchosaurus_
(_Lign. 231_), in our New Red Sandstone, and the probability that the
South African reptiliferous deposits may, from their position, belong
to the Triassic Epoch, induce me to give a somewhat extended notice
of these extraordinary fossils: and I am led to do so on another
account, namely, because the memoir,[667] of which the following is a
brief abstract, is so excellent an example of the manner in which such
investigations should be conducted, so as to arrive at any satisfactory
conclusions as to the characters and relations of the lost types of
beings, whose fragmentary and petrified relics are the only vestiges
that remain.
[666] Hence the generic name, _Dicynodon_: from δις (twice), and
κυνὁδονς (canine tooth).
[667] Prof. Owen’s Memoir on the Dicynodon, Geol. Trans. 2d ser. vol.
vii. pp. 59, _et seq._; and plates iii. to vi.
The fossils under consideration were exhumed some years since by
Mr. Andrew Geddes Bain, from the intensely hard argillo-calcareous
nodules of the sandstone strata which range over an immense tract of
country beyond the mountains north of Capetown,[668] The extensive
series of these and other fossils from South Africa, collected by
the indefatigable labour of Mr. Bain, have lately been deposited in
the British Museum; but the specimens described and figured in Prof.
Owen’s Memoir, above alluded to, are nearly all that have as yet been
successfully worked out from the exceedingly hard matrix in which the
bones are imbedded. These consist of crania and jaws, referable to four
species.[669]
[668] For a notice of the geological structure of this region, see Mr.
Bain’s paper in Geol. Trans. 2d ser. vol. vii. pp. 53, &c.; and the
abstract of a later Memoir by Mr. Bain, in the Literary Gazette, Dec.
18, 1852 (No. 1874).
[669] Namely, Dicynodon lacerticeps (_lizard-head_), D. testudiceps
(_turtle-bead_), and D. strigiceps (_owl-head_), the trivial names
of which have reference to the general form of the head; and D.
Bainii, the largest, but unfortunately as yet the least known species,
which takes the name of the intelligent and energetic discoverer and
collector of the whole.
[Illustration: Lign. 232 and Lign. 233. Dicynodon lacerticeps. (_Owen._)
_South Africa._
(_See Geol. Trans. 2d ser. vol. vii. pl. iii._)
_The letters of reference correspond in the two figures._
Lign. 232. Side view of the Cranium and Lower Jaw: 1/3 _nat. size_.
Lign. 233. Upper aspect of the Cranium: 1/3 _nat. size_.
_Cranium and Upper Jaw._
_a, a._ Intermaxillary bone.
_b, b._ Nasal.
_c, c._ Frontal.
_d, d._ Maxillary.
_e, e._ Prefrontal.
_f, f._ Lachrymal.
_g, g._ Malar.
_h, h._ Post-frontal.
_i, i._ Parietal.
_k, k._ Temporal.
_l, l._ Tympanic.
_m, m._ Mastoid.
_n, n._ Nasal apertures.
_o, o._ Orbits.
_oc, oc._ Basi-occipital.
_t, t._ Temporal fossæ.
_t′, t′._ Canine teeth in the upper jaw.
_Lower Jaw._
1. Dentary bone.
2. Coronoid.
3. Opercular.
4. Angular.
5. Articular.
6. Surangular.
]
The most striking character in these crania is the presence of a pair
of long, sharp-pointed, gently curved tusks, implanted in the superior
maxillary bones, and which descend, one on each side of the fore-part
of the lower jaw, as seen in _Ligns._ 232 and 233, _t_, _t′_. This
is a dental character which, with this exception, is peculiar to the
mammalia (the Walrus, Musk-deer, and Machairodus), and is rare even in
that class.
_Examination of the skull._--One of the crania showed the median
undivided process of a single _intermaxillary_ bone, ascending and
separating _two distinct anterior nasal apertures_; in another, the
boundaries of a very much contracted cranial cavity were evident:
these characters combined to prove that the skulls were referable to
air-breathing oviparous and cold-blooded animals, or Reptiles; but
neither to Crocodilians nor Chelonians, and for the following reasons:--
1stly. The originals were not mammalians; for no mammalian has the
_intermaxillary bone single_ (as in _Lign. 233, a_), or the _external
bony nasal aperture double_; and neither mammalian nor bird has the
cavity for the brain so relatively small as in this fossil.
2dly. They were not Crocodiles; for in all crocodiles the
intermaxillary bone is divided by a suture, and the anterior nasal
aperture is single and on the median line, as in mammalia.
3dly. They were not Chelonians; for all turtles have the nasal opening
single and placed in the middle of the fore-part of the skull, in the
very situation which, in the Dicynodon, is occupied by the convex
imperforate median plate of the broad intermaxillary bone.
4thly. They could not be Fishes, as those animals have no well-defined
external respiratory nasal apertures.
5thly. They were neither Batrachians (frogs) nor Ophidians (serpents);
for, although the reptiles of these two orders have a single
intermaxillary and double nostrils, like the fossils, the latter are
at once separated from them by the presence of a strong and complete
zygomatic arch (_Ligns._ 232 and 233, _g_, _d_), continued from the
tympanic bone to the large immovably articulated superior maxillary.
Lastly, the characters last named, and the presence of vertical
tympanic pedicles (_Lign. 232, l_), suspended by their upper part to
the junction of the zygomatic and mastoid bones, prove the affinity to
the lacertians or true lizards.
These bidental crania have certain characters in common with that of
the Rhynchosaur, which is also, as we have before seen, of the true
lacertian group, but the Dicynodonts are more nearly allied to the
Crocodiles and the Chelonians than the Rhynchosaurus appears to be.
Referring to the original Memoir for anatomical details, I must limit
this notice to a few additional general remarks. Both the jaws are
edentulous, with the exception of the pair of tusks, as in Chelonians;
there are no traces of teeth, or of their sockets, in the lower jaw,
which is short and very deep, and anchylosed at the symphysis, as in
turtles; the alveolar border forms a smooth trenchant edge, which shuts
within the corresponding part of the upper jaw: it is probable that
both jaws were covered by horn, as in the chelonians. The tusks are
implanted in wide and deep conical alveoli in the suborbital part of
the maxillary bone, and project about two inches beyond the sockets
(_Lign. 232_); they are long and pointed, and are directed downwards
and forwards, with a slight backward curve, and slightly converge
towards their extreme points (_Lign. 233_). These teeth consist of
a simple body of unvascular dentine, with a very thin external coat
of enamel. The tooth-ivory is more dense than in any known reptile,
and approaches in its intimate texture that of the canines of the
carnivorous mammals. The base of the tooth has a conical cavity
(_Lign. 234_), indicating a persistent matrix or dental pulp, the
rest of the tooth without the socket being solid. There are no traces
whatever of the germs of successional teeth. It is therefore inferred,
that, like the tusks and scalpriform incisors of mammalia, the canine
or maxillary teeth of the Dicynodon were capable of constant growth
and renovation; thus offering an approach to the typical dentition of
mammalia, unknown in any other reptiles.
As the points of the teeth in the only known perfect specimen are
unworn, it is inferred that these tusks were not employed either as
instruments for obtaining food, as in the Dugong, or for locomotion, as
in the Walrus, but were simply offensive and defensive weapons.[670]
[670] See Prof. Owen’s detailed account of these curious dental organs
in the Memoir already referred to, and in the _Art._ Teeth, in the
Cyclopædia of Anatomy and Physiology.
[Illustration: Lign. 234.
Dicynodon testudiceps. (_Owen._)
(Geol. Trans. 2d ser. vol. vii. pl. v. figs. 3 & 4.)]
Fig. 1.--Longitudinal section of the fang
of the tooth implanted in its
socket: 1/3 _nat. size_.
1_a_.--Transverse section of the tooth.
A few sub-biconcave vertebræ and other undetermined bones were
associated with these remains; and many similar crania, both with and
without the tusks, and other cranial remains with jaws armed with
numerous teeth, as well as indications of smaller reptiles, form
part of Mr. Bain’s collections now in the National Museum, awaiting
the skilful manipulation of the experienced workman to clear away
their hard investing matrix, and the scientific examination of the
palæontologist to elucidate their zoological characters.
Telerpeton Elginense (Mantell). _Ligns._ 235 and 236.--This is
the oldest Reptile yet known.[671] Its remains consist of the
impression[672] of a skeleton of a small, four-footed, vertebrate
animal, on a block of the Old Red or Devonian Sandstone from Spynie,
near Elgin, North Britain. It was obtained by Mr. Patrick Duff, in
1851; and a detailed description of this unique fossil, with an
illustrative plate, will be found in the Quarterly Journal of the
Geological Society, vol. viii. pp. 100, _et seq._; together with a
notice by Captain Brickenden of the geology of the district where
the specimen was found, and a paper on some fossil foot-prints,[673]
discovered by this geologist in the same rock.
[671] The word Telerpeton simply denotes the remote antiquity of this
Devonian reptile of Scotland, τἡλε (far off), ἑρπετον (reptile); the
trivial name, _Elginense_, records the locality from whence it was
obtained.
[672] A model of this most delicate and valuable impression has been
deposited in the palæontological gallery of the British Museum.
[673] A general notice of the fossil foot-prints, or _Ichnolites_, that
have been referred to Reptiles will be given at a subsequent page of
this chapter.
By reference to _Lign. 235_, it will be seen that the cranium is almost
wholly lost; a few conical teeth, mostly of a very small size, were
observed in connexion with the vestige of the jaws. The spinal column
is represented by the impressions of about thirty-six vertebræ, eleven
or twelve of which belong to its caudal portion. The vertebræ present
some faint evidence of their possessing a biconcave form; the length of
one of the dorsal vertebræ is 1/9th of an inch. There are twenty-one
pairs of long slender ribs. The pectoral arch and anterior extremities
have nearly disappeared in the fracture of the stone. The pelvis
and sacrum are very obscure; the latter is formed probably of two
anchylosed vertebra;. The thigh-bones are somewhat curved; the tibia is
gently bowed, and expanded at each extremity. There are no remains of
the feet.
[Illustration: Lign. 235. Telerpeton Elginense (Mantell). _Dev._
_Elgin._
Impression of the skeleton (_nat. size_); showing the outline of
the vertebral column, ribs, pelvis, femora, tibiæ and fibulæ, part
of the caudal series of vertebræ, the left humerus, radius, and
ulna, imperfect traces of the right anterior extremity, and obscure
indications of part of the cranium.]
_a._ The remains of the cranium.
_b, b._ Imprints of portions of the anterior extremities.
_c, c._ Well-defined impressions of the thigh-bones and leg-bones, with
an obscure sub-quadrangular pelvis.
1. One of the teeth: _nat. size_ and _mag._
The structure of this reptilian skeleton, as far as the specimen can
serve to show, indicates a peculiar type of organization, in which,
as in numerous other extinct forms, in this, as in other Classes,
osteological characters are associated which in existing oviparous
quadrupeds are restricted to distinct orders and genera.
[Illustration: Lign. 236.
Telerpeton Elginense (Mantell).
Outline of the restored form of the original reptile: 1/2 _nat._]
The _lacertian_ affinities of the Telerpeton are well marked in the
relative size and form of the bones of its extremities, the situation
of its pelvis, and probably in the articulation and the length of its
ribs; but the contracted, biconcave centrum, and the short neural spine
of the vertebræ, as well as the horizontality of the articulating
surfaces of the zygapophyses, and the general uniformity of character
throughout the spinal column, are to be regarded as _batrachian_
modifications. Probably the original was a peculiar type, which, in the
present state of our knowledge, it would be rash to ascribe to either
order. The length of the original animal could not have exceeded six or
seven inches. _Lign. 236_ represents in outline the probable form of
this small, but most interesting reptile.
V. Pterosaurians, or Flying Reptiles.--Pterodactylus (_wing-fingered
reptile_). _Lign. 237._ _Petrif._ p. 187; _Wond._ p. 577; _Bd._
pl. xxi. xxii.--The extinct reptiles denominated Pterodactyles,
constituting a few genera of an order of Saurians organized for
aërial life,[674] are unquestionably the most marvellous even of the
wonderful beings which the relics of the Age of Reptiles have enabled
the palæontologist to reconstruct. With a long-snouted head and long
neck, much resembling that of a bird, bat-like wings, and a small
trunk and tail, with lacertian affinities in its skull, teeth, and
skeleton, and with a bird-like structure of sternum and scapular arch,
these creatures present an anomaly of structure as unlike their fossil
contemporaries, as is the duck-billed Ornithorhynchus, of Australia,
to existing animals. The cranium, or brain-case, is small; the jaws
are either long, and armed with numerous sharp-pointed teeth, or
toothless, like those of a bird. The teeth of the Pterodactyle are
all laniary; they are simple, of a conical form, recurved, with but
little difference in their form and size, and implanted in distinct
sockets, with wide intervals between each. In some species there are
twenty-eight or thirty in the lower, and twenty-two in the upper jaw.
[674] The only known recent reptile at all analogous is the little
_Draco volans_ of the East Indian Islands; but even this can scarcely
be regarded as a flying animal, its lateral membranous expansions,
which are rather parachutes than wings, and formed by elongated ribs,
not by the fingers, presenting but a rudimentary condition of wings
compared with those of the Bat and the Pterodactyle.
The orbit is very large; the sclerotica consists of an annular row
of bony plates, but less in number than in the Ichthyosaurus; the
external orifice of the nostrils is near the orbits; remains of the _os
hyoides_ (bone of the tongue) have been observed.
[Illustration: Lign. 237. Pterodactylus crassirostris: 1/2 _nat. size_.
_Oolite._ _Solenhofen._]
The cervical vertebræ are large and strong, and capable of great
flexibility forwards and backwards, probably to allow the head to fall
back to the centre of gravity during flight. There are frequently
traces of ossified condition of the tendons of the muscles of the neck.
This is well seen in _P. macronyx_ and _P. crassirostris_ (_Lign.
237_), and is a peculiarity dependent on the additional support required
by the long neck of the animal.
The dorsal vertebræ are from seventeen to twenty in number. The sacrum
is formed by the coalescence of two vertebræ only, as in existing
reptiles, and not of many, as in birds and certain extinct saurians.
The tail is generally short, an unusual character with saurians; but a
species with a long tail occurs at Solenhofen.
There are five toes or digits on each foot; the outer finger of the
fore-arm is immensely elongated, for the support of a membranous
expansion (the impression of this wing-membrane is preserved on the
stone in some examples); and the other digits, of fore and hind feet,
terminated in long curved claws. The size and form of the extremities
show that the _Pterodactylus_ was capable of perching on trees, of
hanging against perpendicular surfaces, and of standing firmly on the
ground, when, with its wings folded, it might crawl on all-fours, and
walk or hop like a bird. A reference to the graphic description of the
characters and probable habits of these beings, by Dr. Buckland, _Bd._
i. p. 221, and the beautiful illustrations accompanying it (_Bd._ ii.
pl. xxi. xxii.), will equally instruct and gratify the reader.
The most perfect examples of the _Pterodactyles_ have been discovered
in the lithographic stone of Monheim, Pappenheim, and Solenhofen, where
their bones are associated with the remains of _Dragon-flies_ (see
p. 551) and other insects. In England, bones of these reptiles have
been obtained from the Lias of Lyme Regis, from the Oolitic slate of
Stonesfield, from the Wealden strata of Tilgate Forest, and the Chalk
of Kent.[675] One of the most interesting British specimens consists
of a considerable part of the skeleton of a species about the size
of a Raven, discovered by the late Mary Anning, in the Lias of Lyme
Regis, and now deposited in the British Museum.[676] It consists of
the principal bones of the extremities, and of several vertebra:, and
is figured and described by Dr. Buckland, _Geol. Trans._ 2d ser. vol.
iii. pl. xxvii. This specimen is distinguished by a greater length of
the claws (whence the name of the species, _P. macronyx_, _long-claw_,)
than in any previously known.
[675] For a detailed description of the Pterosaurian remains from the
English Chalk, with numerous beautiful illustrations, see Prof. Owen s
_Monograph_, published by the Palæontographical Society, 1851. Other
important memoirs on Pterodactyles and their structure, not mentioned
in the text, are, by Von Meyer, in _Nova Acta Acad. Nat. Curios._ vol.
xv. part ii. and _Palæontographica_, part i. 1846; Goldfuss, _Nova
Acta_, vol. xv. part i., and _Reptilien der Vorwelt_, 1831; Prof. Owen
_Quart. Journ. Geol. Soc._ vol. iii. and Mr. Bowerbank, _ibid._ vol. iv.
[676] See _Petrif._ p. 189.
The remains of the Pterodactyles of the Chalk, for the most part,
indicate a large size for the original animals. It has been estimated
that some of these gigantic flying reptiles possessed an extent of wing
surpassing that of the great albatross. The _Pterodactylus Cuvieri_ had
probably an expanse of wing not less than eighteen feet from tip to
tip; another Chalk species, _P. compressirostris_, fifteen feet; whilst
the _P. macronyx_, of the Lias, measured about four feet seven inches
from the extremity of one wing to that of the other.[677]
[677] Bowerbank, _Rep. Brit. Assoc._ 1851, and Owen, _Monograph_, p.
104.
[Sidenote: CHELONIANS.]
VI. Chelonian Reptiles.--Those singular reptiles, commonly known by the
name of Tortoises and Turtles, and designated by naturalists Chelonia
(from _Chelone_, the Greek term for a Tortoise), are distinguished
from all other animals by the osseous cuirass in which their bodies
are enclosed, the head and neck, extremities, and tail, alone being
excluded. This remarkable bony case is produced by the extraordinary
development of the bones of the thorax and back; and consists of an
under (_sternal_) and an upper (_dorsal_) portion. The breast-plate,
or _plastron_, which is the true sternum, is composed of nine pieces
of bone, eight of which are in pairs, and the ninth, or odd plate, is
situated between the four anterior plates. The variation in the form
of these plates is considerable, and affords important distinctive
characters. In the young state of land and fresh-water tortoises, there
are vacancies between the pieces, which are filled up in the adult, the
whole being ultimately united into one bony plate; but in the marine
turtles (and also in the _Trionyces_, or soft tortoises), these pieces
do not completely unite, and interspaces always remain. The bones of
which the dorsal buckler, _carapace_, or upper shield is composed
consist of eight of the ten pairs of ribs, united by a longitudinal
series of angular plates, which are attached to the annular part of
the vertebra throughout the whole, or a great part of their length,
according to the age and species of the individual.[678] Numerous
modifications exist in the form of the buckler, in its flatness or
convexity, in the degree of extension of the ribs, and their angular
plates, and in the characters of the scutes or horny integument with
which the carapace is covered; and with corresponding variations in the
head, and in the locomotive extremities, in the numerous species and
genera of the Chelonian reptiles, according to their adaptation to a
terrestrial, fluviatile, or marine existence.
[678] In the Monograph on Eocene Reptiles, 1849, Prof. Owen has given
a succinct account of the carapace and plastron of the _Chelone_,
and a brief notice of the composition and homologies of these bony
encasements in the Tortoise, with references to more particular and
comprehensive memoirs by himself and others.
The animals of this order are arranged in four principal groups, viz.
the marine, or Turtles (_Chelones_); the fluviatile, or river-Tortoises
(_Trionyces_); the marsh-Tortoises (_Emydes_); and the terrestrial or
land-Tortoises (_Testudines_). The marine Chelonians generally feed
upon vegetables; the _Emys_ and _Trionyx_ approach more nearly to the
terrestrial than to the marine species; they are carnivorous, feeding
on frogs, fishes, fresh-water mollusca, and other small animals. The
_Trionyces_ differ from their congeners in being destitute of a horny
external integument, having no scutes on the buckler or any other
part of the body but the osseous carapace is invested with a strong
tough skin, which equally covers the dorsum and sternum, to which it
firmly adheres; the dermal surface of the bones in these Tortoises is
always rugose, and either granulated, or covered with punctations and
depressions. The buckler of the Trionyces is of a depressed form, with
a soft flattened margin. The Testudinidæ, or land-Tortoises, are too
well known to render any description requisite for our present purpose.
In the marine species, eight pairs of ribs and thirteen plates of the
longitudinal series form the buckler; the ribs or costal plates are
united to each other through a great part of their extent; but towards
their distal or outer extremities each rib contracts, and terminates
in a point, which is supported on a marginal series of bony plates;
the intervals between the ribs are filled up in the living animal by a
cartilaginous membrane which never becomes ossified. This character,
therefore, affords an important aid in the discrimination of the fossil
remains of this family.[679]
[679] The reader will recognise this peculiarity in the gilded skeleton
of the carapace of Turtles, frequently exhibited in the soup-shops of
the metropolis.
In the terrestrial and the marsh Tortoises, the ossification is
complete in the adult state; but in the fluviatile Trionyces, which
are without a horny integument, there is no border, or marginal series
of bony plates, and the extremities of the ribs are therefore always
distinct, and generally have an obtuse extremity. The skeletons of
the three groups present corresponding modifications, and an accurate
knowledge of the osteology of the recent animals is necessary to
enable the palæontologist to arrive at secure conclusions as to the
characters and relations of the fossil species.[680] We can only
advert to one remarkable osteological character,--the construction
of the shoulder, which differs from that of all other animals, in
being situated within the cavity of the thorax, instead of without.
In consequence of this modification, a process of the shoulder-blade
(_scapula_ or _omoplate_), termed the _acromion_, is largely developed,
and the shoulder-bone is tri-mucronate, or three-pronged, consisting of
a short, thick head, containing a concavity (which, with that on the
coracoid-bone, forms a socket for the arm-bone), and of two diverging
branches. This form is so peculiar, that the collector can be at no
loss to recognise the shoulder-bone of a _Chelonian_, should it come
under his notice with other fossil relics (see _Foss. Til. For._ pl.
xix. _fig._ 11). The shoulder-blade and its associated coracoid-bone
undergo certain modifications in the three groups of Turtles, by
which the anatomist may pretty certainly determine the terrestrial,
fluviatile, or marine character of the animals to which they belonged.
The successful application of a perfect knowledge of this department of
osteology, is admirably exemplified in the works to which reference has
been made; and even but a slight acquaintance with its principles will
often enable us to obtain some general information as to the nature and
relations of fossil Chelonians.
[680] The student should consult Cuvier’s _Ossemens Fossiles_, tom. v.
part ii^{me.} chap. ii.: and Prof. Owen’s _Monographs_, published by
the Palæontographical Society, 1849, 1851, 1853. The Penny Cyclopædia,
_Art._ Tortoises, contains an excellent summary of the osteology of
these reptiles, also an abstract of Professor Owen’s Report on the
Fossil _Chelonia_.
The student will remember that all the Chelonians are edentulous, _i.
e._ toothless; their bony jaws being covered by horny sheaths, as in
birds; these mandibles are therefore the only dental organs that can
occur in a fossil state.
[Sidenote: TURTLES AND TORTOISES.]
Fossil Turtles and Tortoises.[681]--Some of the earliest indications of
the presence of Reptiles on our planet are afforded by the foot-prints
of Chelonian animals on the surfaces of the layers of sandstone of
the Old Red formation at Elgin, and of the New Red in Dumfriesshire,
at Storeton, near Liverpool, and at some places in Germany (see _Bd._
i. p. 259, and p. 265, note). But no osseous remains of the animals
of this family have hitherto been found in strata antecedent to the
Oolite. The Solenhofen quarries (Kelheim) have yielded the bones and
carapaces of several Emydian tortoises, and some remains of Chelonians
have been found at Stonesfield, and in the Portland Sandstone.[682]
In the Jura limestone at Soleure, two large species of Emydians have
been discovered. The Wealden and Purbeck formations abound in Chelonian
remains of both fluviatile and marine genera. From the Isle of Purbeck
numerous fine examples have been obtained;[683] my own researches
in the strata of Tilgate Forest (_Foss. Til. For._ p. 60) have also
brought to light several species, and in particular an interesting
Chelonian related to the soft-skinned, fresh-water tortoises,
_Trionyces_ (_Geol. S. E._ p. 255). In the Cretaceous formation of
England the remains of these reptiles are not frequent. The Greensand
of Cambridgeshire (_Rep. Brit. Assoc._ 1841, p. 172,) has yielded a
marine species, and that of Kent a fine Emydian form (Owen, _Monog._
1851); and in the White Chalk a few examples have been obtained, to
which we shall hereafter more particularly allude. On the Continent
fine examples have been found in the slate of Glaris (see _Bd._ pl.
xxv′.); and in the upper Cretaceous strata of the Netherlands, at
Maestricht, and at Melsbroeck, near Brussels, many beautiful specimens
of fresh-water tortoises (_Emydes_), and marine turtles (_Chelones_),
have from time to time been obtained; these are figured and described
by Baron Cuvier (_Oss. Foss._ tom. v. pp. 236, 239). In the Eocene
strata of England, several species of Chelonians have been collected;
of these eleven belong to the marine genus _Chelone_; eight to the
fresh-water _Trionyx_; and eight to the marsh-tortoises, _Emys_ and
_Platemys_. The Isle of Sheppey and Hordwell have yielded the majority
of these relics; the turtles are smaller than the recent analogues,
which now inhabit intertropical latitudes.[684] The Eocene strata
of France contain several fresh-water tortoises, some of which are
referable to the Emydes, and others to the Trionyces. From the gypsum
beds, near Paris, the remains of one or two species of Trionyx have
been obtained (_Oss. Foss._ tom. v. p. 222), of another at Aix, in
Provence, and of three or four species in other localities. A fine
specimen of fresh-water tortoise from Œningen, near Constance, is
described and figured by Professor Bell in Geol. Trans. 2d ser. vol.
iii. The fossil remains of _Testudinidæ_, or land-tortoises, are
exceedingly rare. No well-determined remains are known in the British
strata; the impressions of scutes found in the Stonesfield slate, and
the foot-prints above described, being the only indications of the
existence of these reptiles. The presence of land-tortoises in the
strata of France appears to be equally problematical, for the relics
obtained from Montmartre and Aix (_Oss. Foss._ p. 245) afford no
certain data as to the character of the original.
[681] See _Rep. Brit. Assoc._ 1841, pp. 168, et seq.
[682] See _Rep. Brit. Assoc._ 1841. pp. 160 and 169.
[683] Some of the most beautiful of these almost perfect specimens
have lately been figured and described by Prof. Owen in his Monograph
on the Fossil Chelonian Reptiles of the Wealden and the Purbeck;
Palæontographical Society, 1853.
[684] Rep. Brit. Assoc. 1841, p. 177, and Monograph on Fossil Reptiles,
Pal. Soc. 1849, in which the anatomical details are given with the
characteristic accuracy and minuteness of the author.
The Tertiary formations of India, however, have furnished decided
examples of fossil terrestrial tortoises; and among the innumerable
relics of the beings of an earlier world, which the indefatigable
labours of Dr. Falconer and Captain Cautley have brought to light, and
which those accomplished naturalists have so skilfully developed, are
the remains of land tortoises of prodigious magnitude (_Colossochelys
atlas_); one specimen indicating a length of twelve or fourteen feet,
with a breadth and height of corresponding proportions! These remains
are associated with the bones gigantic extinct mammalia, allied to the
_Palæotheria_ and other pachyderms of the eocene deposits of the Paris
basin; and with those of Emydian and Crocodilian reptiles.[685]
[685] _Petrif._ pp. 11 and 468.
Fossil Marine Turtles.--In illustration of this subject, I select a
specimen discovered in the lower Chalk, at Burham, Kent, which is
remarkable for its beautiful state of preservation, and its peculiar
osteological characters.
[Illustration: Lign. 238. Chelone Benstedi: _nat. size_.
_Chalk. Kent._
The dorsal shield or carapace of this specimen admits of being removed;
and four sternal plates, a coracoid-bone, and several vertebræ are then
exposed.]
Chelone Benstedi. _Lign. 238._--To Mr. Bensted, of Maidstone, whose
discoveries have rendered his quarry of Kentish Bag classic ground to
the British palæontologist, I am indebted for this splendid fossil
turtle. The quarry whence it was obtained is situated at Burham, a
short distance from the banks of the Medway, between Chatham and
Maidstone, and presents a good section of the lower Chalk. This
locality is rich in fossil remains, rivalling in this respect the
quarries near Lewes, Worthing, and Arundel, in Sussex. Two other
fossil Turtles have been obtained from this quarry, and now enrich
the cabinets of Sir P. Egerton and Mr. Bowerbank. Other relics of
Chelonians found in this place are four marginal plates of the
carapace, and fragments of ribs,[686] some marginal plates of a much
larger individual, mandibles, and other fragments, which are noticed
in Prof. Owen’s Monograph, 1851. The specimen, of which _Lign. 238_ is
a reduced figure, consists of the dorsal buckler or carapace almost
entire; it is of a depressed elliptical form, with a longitudinal
median ridge; it is six inches in length, and three and a half inches
in breadth across the middle. It is composed of eight ribs, or costal
plates, on each side the dorsal ridge, which is formed of ten neural
plates; and there is a border of marginal plates. These plates are
united to each other by finely indented sutures, and bear the imprints
of the horny scutes, or tortoise-shell, with which they were originally
invested. The expanded ribs are united throughout the proximal half
of their length, and gradually taper to their marginal extremities,
which are supported by the plates of the osseous border.[687] This
description applies to the specimen as seen in _Lign. 238_; but Mr.
Bensted so skilfully cleared away the chalk as to admit of the
removal of a great part of the dorsal shield, by which means some of
the vertebræ, four sternal (_hyosternal_ and _hyposternal_) plates,
and one of the coracoid bones are displayed. This brief description
will suffice to convey a general idea of the characters of this
fossil, which differs from any known recent turtle, and possesses
some anomalous features, that appear to indicate some slight Emydian
affinities.
[686] See _Geol. Proceed_, vol. iii. p. 299.
[687] See also _Phil. Trans._ 1841, p. 153, pl. xi. and xii.; and
_Palæontograph. Monograph_, 1851, p. 4, plates i. ii. and iii.
[Illustration: Lign. 239.
Beak or Mandible of a Turtle: _nat. size_.
_Chalk. Lewes._]
Among the numerous fossils obtained from the Chalk of Sussex, the only
trace of a Chelonian reptile that has come under my observation is the
bony mandible or beak of a Turtle, _Lign. 239_. Its surface displays
a fibrous cancellated structure, denoting the attachment of the horny
sheath with which, in a recent state, it was covered. More or less
perfect specimens of such mandibles also occur in the Chalk of Kent and
elsewhere, but no bones of the skull have yet been met with in that
deposit. In the Greensand of Cambridgeshire, however, the cranium of a
small turtle has been found. It is figured and described by Prof. Owen
as _Chelone pulchriceps_ (_Monograph_, 1851).
Chelone Bellii. _Lign. 240_, _Petrif._ 155.--In the strata of Tilgate
Forest, fragments of the carapace, of the plastron or sternum, and of
the marginal plates, with some of the bones of the extremities, of a
large marine turtle have been discovered; several specimens are figured
in _Foss. Til. For._ pl. vi. and vii. Some examples must have belonged
to an individual at least three feet in length. Unfortunately, the
specimens hitherto obtained are very imperfect, and do not exhibit
essential distinctive characters, with the exception of the ribs, which
are united to within a short distance of their distal or marginal
extremities; hence the costal interspaces are reduced to much smaller
dimensions than in any recent or fossil Turtles with which I have had
the means of comparing them. The fragment of a rib, imbedded in Tilgate
grit, figured _Lign. 240_, well exhibits this character.
[Illustration: Lign. 240. Chelone Bellii[688] (G. A. M.). _Wealden._
_Tilgate Forest._
Portion of a costal plate, and the extremities of a rib: _nat. size_.
(_Foss. Tilg. For._ pl. vi. _fig._ 2.)]
_a._ The striated pointed extremity of rib.
_b._ The distal portion of the costal plate.
[688] The remains of this reptile were noticed in the "Fossils of
the South Downs, or Illustrations of Geology of Sussex," 4to. 1822,
p. 47, and subsequently figured in the "Illustrations of the Geology
of Sussex, with figures and descriptions of the Fossils of Tilgate
Forest," 4to. 1827, p. 60, pl. vi. and vii.; and this extinct _Chelone_
was regarded as a species, characterized by the great development of
the rib-plates, and named after Professor Bell, the eminent zoologist,
in the first Edition of the "Medals." But in the _Monograph_, _Weald.
Rept._ 1853, this determination has lately been overlooked; and the
specimen figured _Tilg. Foss._ pl. vi. _fig._ 2, is referred to the
newly named _Ch. costata_, characterized by its broad and prominent
ribs. A third name even (_Ch. Mantelli_) has been bestowed on this
interesting fossil, by a German palæontologist.
Fossil fresh-water Tortoises.--The remains of fresh-water Tortoises,
referable to the _Emydidæ_, occur in the Purbeck and Wealden strata
(Owen’s _Monograph_, 1853, and _Rep. Brit. Assoc._ 1841); the
resemblance of some of these to the Jurassic species from Soleure was
noticed by Cuvier (_Oss. Foss._ vol. v.). Among the Chelonian remains
of the Wealden, some of the most remarkable are the costal plates
and other bones of a Tortoise, which in its essential characters is
closely allied to the Trionyces,[689] but differs from the recent
forms, in having possessed a dermal horny integument, formed of
scutes of tortoise-shell. The chelonians of the genus Trionyx (so
named from their having three claws) have the extremities of the ribs
free, and not articulated to a border of marginal plates, and there
are intervals between their costal plates even in the adult state.
The external surface of the bones of the buckler is covered with
granulations, or with little pits, for the attachment of the soft
skin, the only integument with which these animals are invested; and,
being destitute of horny scutes, their bones exhibit no furrows, as
in the other genera. But the fossil rib-plates (see _Lign. 241_) have
a shagreen-like or punctated surface, like the recent Trionyces, and
at the same time bear the imprints of horny scutes; and, instead of
being nearly of an equal width throughout their entire length, as in
the existing species, have one extremity much wider than the other,
as in the land-tortoises. From the slight degree of convexity of
the ribs, it is evident that the carapace was much flattened, as in
the Trionyx.[690] Except in having a defensive dermal integument,
and agreeing in this respect with many of the Crocodilian reptiles,
with which its bones are associated, the original must have closely
resembled the existing predaceous fresh-water soft Turtles; and,
doubtless, like those reptiles, inhabited the muddy beds of lakes and
rivers, preying upon the eggs and young of the larger reptiles, and
on the uniones and other fluviatile mollusca, whose shells are very
commonly found imbedded with its remains.
[689] The relations of these peculiar remains to _Trionyx_ were pointed
out in _Foss. S. D._ 1822, p. 47.
[690] See _Petrif._ p. 157, &c.
[Illustration: Lign. 241. Tretosternon Bakewelli; [691] 1/3 _nat. size_.
_Wealden._ _Tilgate Forest._
(_Foss. Tilg. For._ pl. vi. _fig._ 1.)
One of the costal plates.]
[691] This Tortoise, with the sanction of Baron Cuvier, was described
under the name _Trionyx_, in _Foss. Tilg. For._ 1827, p. 60, and its
distinctive characters were pointed out. In _Geol. S. E._ 1833, p.
255, the specific name _Bakewelli_ was proposed in honour of the late
Robert Bakewell, Esq., whose excellent works have so greatly promoted
the advancement of geology; a privilege to which, as the original
discoverer of the species, and of its zoological relations, I was
fairly entitled. But this name does not appear in the list of British
Chelonians, either in _Rep. Brit. Assoc._ 1841, or in Mr. Morris’s
_Cat. Brit. Org. Rem._ 1843. With a melancholy pleasure I now restore
the name of my lamented friend, as a just, but very inadequate tribute
of respect to his memory.
[Illustration: Lign. 242. Palæophis toliapicus: 2/3 _nat. size_.
_London Clay. Isle of Sheppey._
Six concavo-convex vertebræ of the trunk.]
[Sidenote: FOSSIL SERPENTS.]
VII. Ophidians, or Serpents. _Lign. 242._--The remains of the vertebral
columns of extinct Serpents were discovered many years since in the
London clay of the Isle of Sheppey, and specimens were obtained by
the celebrated Hunter, and preserved in his museum. These specimens,
together with others in the collections of Messrs. Saull, Bowerbank,
Dixon, Combe, and S. Wood, have been figured and described, and their
relations to existing types elaborately worked out, by Professor
Owen.[692] The _Palæophis typhæus_, from the Bracklesham clay, had a
length of about twenty feet, and, from the compressed character of
its caudal vertebræ, was probably a sea-serpent. A somewhat smaller
species also occurs at Bracklesham. The Sheppey specimens are referred
to another species of this extinct genus, namely, the _P. toliapicus_
(_Lign. 242_); it was from ten to twelve feet in length. The remains of
two species of land-serpents, respectively about four and three feet
long, have been found at Hordwell Cliff. These belong to the extinct
genus _Paleryx_, thus named in reference to the near affinities of the
Hordwell vertebræ to those of the recent _Eryx_, one of the Boa and
Python group of serpents.[693]
[692] Geol. Trans. 2d ser. vol. vi. p. 209, &c. pl. xxii.; Rep.
Brit. Assoc. 1841, p. 180; "Dixon’s Geology and Fossils of Sussex,"
pp. 211-217, pl. xii. _fig._ 14; and especially Palæontographical
Monograph, 1850, p. 51, _et seq._; and plates xii. to xvi.
[693] See Monograph on Eocene Reptiles, 1850, from which these notices
of the Eocene Ophidians are abridged.
The vertebræ of Serpents are distinguished by a transversely oblong
anterior concavity, forming a deep cup, and a corresponding posterior
convexity or hall; by the interlocking of the projecting posterior
oblique processes with the anterior pair; and by the oblong tubercle
on each side of the anterior part of the body of the vertebra, for
moveable articulation with the head of the ribs; a spinal column thus
constructed combines in the highest degree perfect flexibility with
great strength.
In addition to the ophidian relics above referred to, fossil vertebræ
of a small serpent (_Palæophis?_) have been found in the Eocene sand
below the Bed Crag, at Kyson in Suffolk;[694] a locality that has
yielded other organic remains of great interest (see chap. xix.; and
_Wond._ p. 258). The only fossils of this order of reptiles known to
Baron Cuvier appear to have been some vertebræ from the bone-breccia of
Cette (_Oss. Foss._ tom. iv. p. 177).
[694] Rep. Brit. Assoc. 1841, p. 181; and Monograph, 1850, p. 66.
Fossil eggs of snakes are occasionally met with in a comparatively
recent limestone, of fresh-water origin, in Germany, near Offenbach,
associated with shells of land and fresh-water molluscs. Like the
turtles’ eggs on the shores of Ascension Island, these ova were
probably laid in the moist mud, and became encrusted and preserved by a
deposit of tufa.[695]
[695] Quart. Journ. Geol. Soc. vol. vi. part 2, p. 42.
[Sidenote: BATRACHIANS.]
VIII. Batrachians.--The reptiles termed Batrachians (from the Greek
name for Frog) are characterized by the metamorphoses which they
undergo in the progress of their development from the young to the
adult state; the Frog, Toad, and Newt are familiar examples of this
order. Their organs of aërial respiration consist of a pair of lungs;
but in their young state they are provided with gills, supported, as
in fishes, by cartilaginous arches. These organs disappear, in most
species, when the animals arrive at maturity; but in a few genera, as
the Siren and Proteus, they are persistent. The skeletons of these
reptiles present corresponding modifications. The skull is, for the
most part, much depressed, and the cerebral cavity small; it is united
to the vertebral column by two distinct condyles, situated on the
sides of the occipital or cranio-spinal aperture.[696] The vertebral
column, in some genera (as, for example, in the common frog), is very
short, and is reduced to eight or ten bones, the caudal vertebræ being
fused into a long cylindrical style; but in the higher organised
Batrachians the spine is composed of concavo-convex vertebræ, as in
the Crocodile: in the lower type, as the Siren, Proteus, and Axolotl,
the vertebræ are biconcave, as in numerous species of fossil Saurians.
The ribs are merely rudimentary, being very short and few; a condition
which has relation to the mode of reproduction in these animals, the
eggs being accumulated and shed at once.[697] Some of the Batrachians
are edentulous, but others have numerous small, conical, uniform,
closely-arranged teeth, placed either in a single row, or aggregated
like the rasp-teeth in fishes.[698]
[696] Saurians, like birds, have a single occipital condyle.
[697] See Dr. Roget’s _Bridgewater Essay_, p. 395.
[698] The variations in the dental system of these animals are given in
_Odontography_, chap. ii. p. 187.
[Sidenote: FOSSIL BATRACHIANS.]
Batracholites; or fossil remains of Batrachians.--The skeletons,
vestiges of the soft parts, and imprints of the feet of several genera
of Batrachians occur in a fossil state in tertiary deposits, all of
which, like the existing races, appear to belong to fresh-water or
terrestrial species. In the pliocene or newer tertiary strata, on the
banks of the Rhine, at Œningen, and in the _papierkohle_ of the Eifel,
several species of Frog, Toad, and Newt, have been discovered. Fossil
frogs of a small species, very similar to the recent, occur in numbers
in a dark shale, overlaid by basalt, in the vicinity of Bombay.[699]
[699] Quart. Geol. Journ. vol. iii. p. 221.
A celebrated fossil of this class is the gigantic Salamander
(_Cryptobranchus_), three feet in length (_Lign. 243_), found at
Œningen (see _Wond._ pp. 263, 580), which a German physician of some
note (_Scheuchzer_) supposed to be a fossil man![700] and he described
it in an essay, entitled "_Homo diluvii testis et Theoscopos_," as
being the moiety, or nearly so, of a human skeleton, with the bones and
flesh incorporated in the stone.[701] A fine example of this fossil
Salamander is preserved in the British Museum (_Petrif._ p. 186).
[700] Phil. Trans, for 1726, vol. xxxiv.
[701] Ample description and figures of this highly interesting fossil
are given by Cuvier, _Oss. Foss._ tom. v. part ii. p. 431, pl. xxv.
xxvi.
[Illustration: Lign. 243. Cryptobranchus Scheuchzeri: 1/11 _nat. size_.
_Tertiary._ _Œningen._]
[Sidenote: LABYRINTHODON.]
Labyrinthodon. _Ly._ p. 290-293; _Wond._ p. 550. By far the most
interesting evidence of the existence of Batrachian reptiles in the
earlier ages of our planet has been afforded by Professor Jäger’s
discovery of the skull, teeth, and other remains of gigantic extinct
animals, allied to the Salamander, in the Upper New Red Sandstone
(_Keuper_) of Wirtemberg.[702]
[702] Über die Fossile Reptilien welche in Würtemberg aufgefunden
worden sind, von Dr. Geo. Friedr. Jäger. 4to. Stuttgart, 1828. See also
Hermann von Meyer’s Notice of the Saurians of the Muschelkalk, Banter
Sandstein, and Keuper, _Quart. Geol. Journ._ vol. iv. pt. ii. p. 40.
These remains were referred by this eminent physician and naturalist
to saurian genera, although the double condyle of the occipital bone
indicated Batrachian affinities. It was reserved, however, for our
distinguished countryman, Professor Owen, to correct the error into
which the German _savant_ had fallen,--remove the obscurity in which
the subject was involved,--determine the natural relations of the
original,--and develope a modification of dental organization of the
most unexpected and interesting character.
Dr. Lloyd, of Leamington, having discovered some fossil teeth and
bones in the light-coloured sandstone of the New Red, at Warwick and
Leamington, submitted them to Professor Owen, who, struck with their
general resemblance to the teeth of the gigantic _Salamandroïdes_ of
Wirtemberg, instituted a microscopic examination of the British and
German specimens. The result proved that the teeth from both localities
possessed a remarkable and complicated structure, produced by the
convergence of numerous inflected folds of the external layer of cement
towards the pulp-cavity; to which, as we have already seen (p. 666),
a very slight approach was made in the tooth of the Ichthyosaurus,
and a still closer approximation by the teeth of certain fishes
(_Lepidosteus_, p. 616). From the intricate meanderings or labyrinthine
inflections observable in the sections of these teeth, Professor Owen
has given the name of _Labyrinthodon_ to these extinct Batrachian
reptiles, and has determined five British species; one of which (_L.
Jægeri_) he conceives to be identical with a species described by my
friend, Dr. Jäger.
The remains of the skeletons of these reptiles, hitherto found in
Warwickshire, consist of portions of the cranium, and of the upper and
lower jaws, with teeth, vertebræ, a sternum, and some of the bones of
the pelvis and the extremities. From a specimen (of _L. scutulatus_)
consisting of an aggregated group of bones, imbedded in sandstone,
comprising four vertebræ, portions of ribs, a humerus, a thigh-bone,
and two leg-bones, with several small osseous scutes, it appears
that one species, at least, resembled the Crocodiles in its dermal
structure. But Professor Owen remarks, that this modification of the
dermal system does not affect the claims of the Labyrinthodonts to be
considered as Batrachians, although all the known living species of
this order are covered with a soft, lubricous, naked integument; for
the skin is the seat of the most variable characters in all animals;
and the double occipital condyle, the simple lower jaw, the palatal
vomerine bones, and the teeth of these fossil reptiles must be deemed
decisive of their essentially Batrachian nature.
From the specimens of the cranium the important fact has been
ascertained, that the Labyrinthodonts had subterminal nostrils leading
to a wide and shallow nasal cavity, which is separated by a broad
and almost continuous palatal flooring from the cavity of the mouth;
indicating, by its horizontal position, that the posterior apertures
were placed far behind the external nostrils; whereas in the recent
air-breathing Batrachians the nasal canal is short and vertical, and
the inner apertures pierce the anterior part of the palate. The nasal
cavities in the Frog are vertical; for this reptile swallows air. The
Labyrinthodonts must, therefore, have breathed air like the Crocodiles,
and were probably provided with well-developed ribs, and not mere
rudimentary styles, as in most living Batrachians.
Tooth of the Labyrinthodon. _Pl. VI. fig. 3._--The tooth of the
Labyrinthodon is of a conical figure, very slightly recurved, and
marked externally with shallow, fine, longitudinal strife. _Pl. VI.
fig. 3^a_, represents (1/2 _nat. size_) a specimen presented to me by
Dr. Jäger. The tooth is implanted, by a single fang, in an alveolar
groove to which it is anchylosed. It consists of a simple central
pulp-cavity, surrounded by a body of dentine, which has an external
thin coat of cement; and a vertical duplication or fold of this cement
penetrates the substance of the tooth at each of the striæ, which are
arranged at intervals of about one line around the entire circumference
of the tooth. The inflected folds of cement extend inwards towards the
centre, in a straight direction for about half a line, then become
undulated, and finally terminate in a dilatation or loop, close to the
pulp-cavity, from which it is separated by a thin layer of dentine.
Within these inflections of the cement, the dentine, or tooth-bone, is
similarly disposed; a layer of dentine lining the folds of cement, and
having corresponding interspaces, which are filled up by the processes
from the pulp-cavity. It is this blending of the cement and dentine
in labyrinthine folds, that gives the peculiar character observable
in transverse sections of the teeth. _Pl. VI. fig. 3^a_, represents
a transverse section of half the diameter of the tooth; the vacancy
in the middle of the line at the bottom is a section of half the
pulp-cavity. _Fig. 3^b_ is a vertical section of a fragment near the
summit of the tooth; and _fig. 3^c_, a highly-magnified view of one of
the anfractuosities, showing a fold of cement, surrounding a fold of
dentine, and in the centre of the latter the termination of a process
of the pulp. The section of the tooth of the Ichthyosaurus, _Pl. VI.
fig. 9_, shows the most simple modification of this structure; the
apparent complication of that of the Labyrinthodon arises from the
inflections of the three elements of dental organization being more
numerous and diversified. But the beautiful plates and the graphic
description of the original discoverer must be seen and perused to
obtain an adequate idea of the exquisite structure of the fossil
teeth; for the distribution of the extremely minute calcigerous
tubes of the dentine is as diversified as that of the constituent
substances. And even after viewing these _chefs-d’œuvres_ of structural
delineations, should the reader have an opportunity of examining a
transverse section of a tooth under the microscope, he will feel how
feebly any engraving can represent the characters of the original.[703]
[703] Professor Owen’s Memoir on the Labyrinthodonts, in _Geol. Trans._
2d ser. vol. vi. pp. 503-543, with five admirable lithographs by that
excellent artist, Mr. Scharf, and the description of the structure
of the teeth, _Odontography_, p. 195, pl. lxiii. lxiv. should be
consulted. See also _Cyclop. Anat._ Art. Teeth.
[Sidenote: ARCHEGOSAURUS.]
Archegosaurus. _Lign. 244_, _Ly._ p. 336, _figs._ 384,[704] 385.--The
occurrence of reptilian remains in deposits of higher antiquity than
the Triassic was first established in 1844, by the discovery of the
skull and other portions of the skeleton of an air-breathing reptile,
the _Apateon pedestris_, related to the Salamanders, and about three
feet in length, in the coal of Münster-Appel in Rhenish Bavaria.
In 1847 Professor Von Dechen obtained, in nodules of argillaceous
ironstone, from the coal-field of Lebach, in the district of Saarbrück,
three species of the same type of reptiles; these have been described
by Goldfuss, under the name of _Archegosaurus_.[705] One of them was
well known to collectors, but had previously been regarded as a fish
(the _Pygopterus lucius_ of M. Agassiz).
[704] The original of this figure of _Archegosaurus minor_ is now in
the British Museum.
[705] See a notice of the researches of Goldfuss, Von Dechen, and Von
Meyer in the geological and zoological history of this interesting
group of batrachoid reptiles, _Quart. Journ. Geol. Soc._ vol. iv. part
ii. (Miscell.) p. 513, _et seq._
The skull and portions of the trunk of this species (_A. Dechenii_),
see _Lign. 244_, indicate an animal three and a half feet in length.
Seventeen dorsal vertebræ, imprints of the ribs, and remains of the
extremities, have been collected. The jaws to beyond the orbit
have small fine conical teeth, longitudinally striated. The eye was
furnished with an osseous ring. The skin, of which a considerable part
was detached, was covered by long, narrow, wedge-shaped, horny scales,
arranged in rows (_Lign. 244_). The cranial bones are characterized
by reticulating grooves and pittings, similar in character to the
reticulate markings on the cranial bones of the Labyrinthodon, but of
a more delicate sculpturing. The original reptiles were quadruped; the
fore and hind feet had distinct toes; but the limbs were feeble, and
only capable of swimming, or, when on land, of a slow creeping movement.
The Archegosaurus is closely allied to the Labyrinthodonts;[706] and,
in the words of Professor Owen,[707] it is "essentially Batrachian,
and most nearly allied to the perennibranchiate, or lowest or most
fish-like of that Order of Reptiles."
[706] We may remark that in the opinion of Dr. Goldfuss and Von Meyer
(_loc. cit._) the Labyrinthodon and the Archegosaurus are saurian
forms connecting the Crocodiles and the Lizards, and representing in
the ancient fauna an arrested or "permanent larva-condition of the
loricated reptiles, as the sirens do among the recent batrachians."
Professor Owen’s estimation of the affinities of these genera is stated
above, and in the _note_ at p. 55, Geol. Journ. vol. iv. part ii.
[707] Quart. Geol. Journ. vol. ix. p. 69.
Parabatrachus Colei.--Under this appellation Professor Owen has lately
described (_Quart. Geol. Journ._ vol. ix. p. 67, pl. ii. _fig._ 1,)
a batrachoid fossil, consisting of cranial and maxillary bones with
teeth, probably from the shale of the Glasgow coal-field, at Carluke,
Lanarkshire. The slab of coal-shale in which the specimen is imbedded
contains also a large scale of the _Holoptychius_ (see p. 618).
[Sidenote: DENDRERPETON ACADIANUM.]
Dendrerpeton Acadianum.[708] (_Quart. Journ. Geol. Soc._ 1853, pp.
58-67, plates ii. and iii.)--The remains of a reptile and a land-shell,
resembling a _Pupa_, were discovered in 1852, by Sir C. Lyell and
Mr. J. W. Dawson, in the interior of an erect stamp of a fossil tree
(_Sigillaria_), in the coal-measures at the South Joggins cliffs,
Nova Scotia. These remains were fully described by Professor Jeffries
Wyman, of Harvard University, U. S., and Professor Owen in the Appendix
to the Memoir by Sir C. Lyell and Mr. Dawson, in the Journal of the
Geological Society, vol. ix. Some of the bones were recognised as
having a near resemblance to those of the recent _Menobranchus_ and
_Menopoma_ (Perennibranchiate Batrachians, inhabiting North American
fresh-waters); the sculptured cranial bones are analogous to those
of the _Labyrinthodon_ and _Archegosaurus_; and the teeth have a
Labyrinthodontoid structure: numerous, small, concentrically striated
scutes, of an irregular oval shape, accompany the bones and teeth.
[708] The _Tree-reptile of Acadia_ (Acadia being the ancient Indian
name for Nova Scotia).
[Illustration: Lign. 244. Archegosaurus Dechenii. 1/2 _nat. size_.
_Coal Formation._ _Saarbrück._]
Fig. 1.--The cranium and part of the lower jaw.
2.--A portion of the skin, or dermal scutes, magnified.
3 and 4.--Magnified figures of two teeth.
The conclusions arrived at by the eminent comparative anatomists to
whose examination the remains in question were submitted, show that the
character of the fossils are those of Perennibranchiate Batrachians;
that, with regard to the long bones, it is not improbable that the
corresponding bones in the _Archegosaurus_ (p. 745) and _Labyrinthodon_
(p. 741) would present similar correspondences with those of the
existing perennibranchiates; and that, although the _Dendrerpeton_
cannot be referred to any known form of the two genera just mentioned,
yet there exists strong evidence of its close affinity with these
extinct Batrachians.
The _Dendrerpeton Acadianum_ was probably between two and three feet in
length. A series of minute biconcave vertebræ were found with the other
remains in the erect tree, these, however, from their relatively small
size, and from other characteristics, are regarded by Professor Wyman
as having probably belonged to some other associated reptile.
The Labyrinthodont reptiles have been regarded as characteristic of the
Permian and Triassic epochs, their remains being found in Germany and
England in rocks of that age. The commencement of the existence of this
family of sauroid-batrachians, however, is of greater antiquity, since
their relics also occur in the formations of the Carboniferous epoch.
The _Archegosaurus_ (p. 745), a batrachian but slightly removed from
the true Labyrinthodont type, has left its well-characterized remains
in the Coal of Germany; the _Parabatrachus_, in that of Scotland;
and the allied _Dendrerpeton_, in the Nova Scotian coal-field. This
last-mentioned great carboniferous formation has, however, afforded
fossil evidence of the existence of the true Labyrinthodonts in the
Coal-period, for some cranial bones, imbedded in a mass of Pictou
coal, lately sent to England by Mr. J. W. Dawson, and the subject
of a Paper by Professor Owen, read before the Geological Society,
were demonstrated by that distinguished palæontologist to have close
affinity with the corresponding parts of the skull of the Triassic
genera _Capitosaurus_ and _Metopias_.
[Sidenote: ICHNOLITES.]
Ichnolites (_Foot-prints on stone_). _Lign. 245._--The sandstones and
mud-stones of many localities retain the track-prints of animals that
have passed along on the surface of the beds when in a soft state.
These foot-prints, or _ichnolites_, either occur as impressions on the
surface originally marked lay the animal in the act of progression,
or as the reverse of such impressions, being casts _in relief_ on the
under side of the layer covering the surface originally impressed. Such
indications of footsteps and trails have been noticed especially in the
forest marble, a member of the Lower Oolite series, where Crustacea
and Mollusks have left their markings, and in the New Red Sandstone,
where the indications of reptilian quadrupeds and of bird-like
bipeds[709] have been here and there preserved in great distinctness.
Tracks referable to Crustaceans have been found by Mr. W. E. Logan,
on the very ancient and rippled surfaces of the Potsdam Sandstone of
North America (see p. 543, _note_); and very lately Mr. J. W. Salter
has communicated to the Geological Society the discovery of markings,
referred by him to the little entomostracous Hymenocaris (see p. 526),
on the Lower Lingula Flags of North Wales,--deposits of as great an
age, if not older. The most ancient reptilian ichnolites are those
discovered by Capt. L. Brickenden[710] in the Old Red, at Cummingston,
near Elgin, which have some resemblance to the track of a club-footed
Chelonian (_Ly._ _fig._ 521); and those of the Devonian sandstone of
Sharp Mountain, Pennsylvania, discovered by Mr. I. Lea,[711] which
exhibit distinct toes, and are probably allied to the Cheirotherian
ichnolites, about to be mentioned, as are also other ancient fossil
foot-tracks in the Carboniferous deposits[712] of Pennsylvania, which
are figured and described in _Ly._ pp. 337-340.
[709] See Ornithoidichnites, in chap, xviii.
[710] Quart. Geol. Journ. vol. viii. p. 97, pl. iii.
[711] Across the ridges of the ripples on this slab is a narrow groove,
passing along between the two rows of foot-prints; this might have been
made by the body or the tail of the animal. _Rep. Brit. Assoc._ 1849,
Sect. pp. 56 and 134; and _Trans. Americ. Phil. Soc._ new series, vol.
x. part ii. plates xxxi. and xxxii.
[712] With regard to the distribution of reptilian life during the
carboniferous and succeeding epochs, see above, page 748.
The sandstones of the New Red or Triassic series frequently retain the
track-prints of animals, and numerous notices of such occurrences have
been published.[713] In addition to the account of these invaluable
evidences of the existence of bygone creatures that is here given, the
attention of students is especially directed to Dr. Buckland’s most
interesting description and illustrations of such as were known when
his Treatise was published (_Bd._ i. p. 259, &c.; and ii. p. 36, pl.
xxvi. &c.).
[713] The following are the principal notices of ichnolites by English
authors which are not referred to in the text:--Cunningham, Yates,
and Egerton on Cheirotherian traces in Cheshire, _Geol. Proc._ vol.
iii. pp. 12-15; Dr. Black on foot-prints at Runcorn, _Quart. Geol.
Journ._ vol. ii. p. 65, pl. ii.; Mr. Cunningham. _Liverpool Lit. and
Phil. Proc._ 1848, p. 129, plates iii.-v.; Mr. Hawkshaw on the New Red
with foot-prints at Lymm, _Rep. Brit. Assoc._ 1842, Sect. p. 56; Mr.
Rawlinson on the same, _Quart. Geol. Journ._ vol. ix. p. 37; Prof.
Harkness on the track-bearing beds of Dumfriesshire, _Rep. Brit.
Assoc._ 1850, Sect. p. 83; _Quart. Geol. Journ._ vol. vi. pp. 389 and
393; and _Annals Nat. Hist._ 1850, vol. vi. p. 203; Sir W. Jardine,
_Annals Nat. Hist._ _loc. cit._ Foreign authorities may be found by
reference to Pictet’s _Traité de Paléontologie_, a new and enlarged
edition, vol. i. 1853, p. 567, _et seq._
The imprints of the feet of some large quadrupeds, having the
fore-paws much smaller than the hinder, have been found in Saxony
(see _Wond._ p. 555, _Bd._ p. xxvi.); and also in strata of the same
age in Warwickshire and Cheshire. The quarries at Storeton Hill,
near Liverpool, are celebrated for the abundance and variety of these
imprints.[714] Some of the strata of sandstone in this locality are
divided by thin beds of clay; a lithological structure which admits of
the ready separation of the stone in the direction of the sedimentary
planes.
[714] The Museums at Warwick, Warrington, and Liverpool are rich in
impressed slabs from the Triassic districts. Numerous fine specimens
may be also seen in the Museum of the Geological Society, Somerset
House, the Museum of Practical Geology, in Jermyn Street, and in the
British Museum (see _Petrif._ pp. 14 and 63).
[Sidenote: RAIN-PRINTS ON STONE.]
Imprints are found on the face of each successive stratum; and on
some of the layers, not only the tracks of animals that have walked
over the clay when soft are distinctly observable, but the surface is
often traversed with casts of the cracks caused by the desiccation
of one layer of clay previously to the deposition of the succeeding
layer of sand or mud; and it often presents a blistered or warty
appearance, being covered with either little hemispherical eminences
or depressions, which an accurate investigation of the phenomenon has
proved to have been produced by showers of rain (_Ly._ figs. 526-528).
On the slabs of sandstone, the forms of the sun-cracks, rain-drops, and
foot-prints appear in relief, being casts moulded in the soft clayey
mud upon which the original impressions were made; while on the clay or
shale, corresponding depressions are apparent.[715]
[715] The impressions of rain-drops on stone were first noticed, and
their origin explained, by Mr. Cunningham. _Geol. Proc._ vol. iii.
p. 99. See also an interesting Paper by Sir C. Lyell, _Quart. Geol.
Journ._ vol. vii. p. 240.
The foot-prints on these strata are of several kinds; some appear to
have been produced by small reptiles and crustaceans; but the principal
imprints are identical with those which have been observed in Saxony,
and are referable to some large quadruped, in which the fore-feet
were of a much smaller size than the hind-feet (_Lign. 245_). From
a supposed resemblance of the imprints to those of a human hand,
Professor Kaup proposed the name of _Cheirotherium_, to designate the
unknown animal which had left these "footsteps on the sands of Time."
But since Professor Owen’s discovery, that the bones and teeth of
reptiles found in similar strata in Warwickshire belong to gigantic
Batrachians, and since the fore and hind-feet of the frog-tribe are
often as dissimilar in size as the impressions of the _Cheirotherium_,
it has been suggested, with much probability, that the foot-prints in
question may be those of Labyrinthodonts; but until the form of the
feet of these extinct Batrachians can be ascertained, this inference
must be regarded as conjectural (_Ly._ _fig._ 331).
[Sidenote: CHEIROTHERIUM.]
[Illustration: Lign. 245. Cheirotherium Kaupii. 1/8 _nat. size_.
Casts of the foot-marks of a gigantic extinct Batrachian, probably a
Labyrinthodon; with casts also of the cracks of the opposed surface.
_Trias._ _Hessburg, near Hildburghausen, Saxony._]
Fig. 1.--Casts of the imprints of a hind and a fore-foot of the same animal.
2.--Similar tracks of another individual on the same stone.
Allusion has already been made to foot-prints, supposed to be those of
tortoises (see p. 729), on slabs of Triassic sandstone in Scotland.
Of these there are five species at Corncockle Muir, in Dumfriesshire:
they are termed _Chelichnus_ by Sir W. Jardine, who has lately
described them in his _Ichnology of Annandale_, a splendid folio work,
illustrated with full-sized lithographs, coloured after nature. They
are accompanied with three other forms of footstep (_Herpetichnus_,
_Batrachnis_, and _Actibatis_), one of which Sir W. Jardine regards as
indicative of an animal probably of a saurian form.
At Grinsill quarry, from which the remains of the _Rhynchosaurus_ (p.
712) were obtained, some small foot-prints have been observed, which,
with some probability, have been referred to that animal (_Rep. Brit.
Assoc._ 1841, p. 146).
A beautifully distinct series of foot-prints, with the mark of a
trailing tail, on a rippled slab from the New Red of Shrewley Common,
Warwickshire, are figured and described by Strickland and Murchison
(_Geol. Trans._ 2d ser. vol. v. pl. xvviii.). This ichnolite has
been provisionally assigned by Professor Owen to _Labyrinthodon
leptognathus_.[716] Similar impressions occur in company with other
Cheirotherian imprints at Storeton Hill and at Grinshill.
[716] Geol. Trans. 2d ser. vol. vi. p. 525. The probable relations of
_Cheirotherium Hercules_ to _Labyrinthodon Jægeri_, and of _Ch. Kaupii_
to _L. pachygnathus_, are pointed out by the same high authority,
_ibid._ pp. 537, 538.
[Sidenote: ON COLLECTING FOSSIL REPTILES.]
On Collecting the Fossil Remains of Reptiles.--The length to which this
article has extended, compels me to omit a retrospect of the geological
distribution of fossil reptiles; and I must refer the reader to the
brief review of the Age of Reptiles in _Wond._ p. 568, _et seq._, and
_Petrif._ p. 147, &c., and close this chapter with some directions
for collecting reptilian remains, and a list of a few British
localities.[717]
[717] An able Summary on British Fossil Reptiles is appended to Prof.
Owen’s Report, _Rep. Brit. Assoc._ 1841, p. 191.
The fossil _Teeth of Reptiles_ are commonly found in as perfect a state
of preservation as those of fishes; and require but the usual care for
their preservation. But the collector should assiduously search for
vestiges of the jaw and cranium; and it is desirable to place in the
same drawer any undetermined bones found associated with the teeth;
as they may ultimately afford some clue to the nature of the original
animal. The microscopical examination of the teeth is to be conducted
in the manner previously directed (p. 639); but for valuable specimens
the lapidary should be employed, and transverse sections made from near
the apex, the middle, and base of the tooth; if due care be taken,
several slices may be obtained from one specimen. I have ten slices
from one tooth of the Labyrinthodon. The bones imbedded in limestone
generally partake of the chemical character of the rock, and are
often permeated with calcareous spar; mere fragments, when polished,
frequently display the internal structure.
The suggestions for repairing fossil bones (p. 46) render further
instructions on that head unnecessary; and the description of the
development of the specimen of Hylæosaurus (p. 689) affords a practical
lesson to the young collector.
When a vertebra is found in an imperfect state, it should be closely
examined on the spot, and, if it present proofs of recent fracture, the
detached processes should be sought for; even if the body of a vertebra
be imbedded in stone, and the processes appear to have been broken off
before it was enveloped in the rock, the corresponding parts will often
be found in the same mass of stone. There is in the British Museum a
very fine Saurian vertebra imbedded in a large slab of Tilgate stone,
in which the spinous process is seen lying in the same block, several
inches distant from the centrum or body; when observed in the quarry
the latter only was exposed, and I was about to detach it from the
slab, for the convenience of carriage, when I perceived indications of
the spinous process. The vertebra was therefore allowed to remain, and
the stone chiselled away, so as to expose the spine; and the specimen
then displayed its present interesting character.
It may frequently happen that a fragment of a large bone,--as, for
example, the thigh-bone of the Iguanodon,--may be obtained from a
quarry; and after an interval of some weeks the corresponding portions
be discovered. This was remarkably exemplified in the first specimen
which revealed to me the peculiar characters of the femur of the
Iguanodon. The lower part, or condyloid extremity, of a gigantic
bone, firmly impacted in a block of Tilgate-grit, was found in a
quarry near Cuckfield; it was evidently but a fragment of the fossil,
for the fracture was recent; I therefore requested the quarry-men
to make diligent search for the corresponding portion, but without
success. Several months afterwards, upon a fresh explosion in the
quarry, the head of a large bone was found loose among the fallen
mass; but there were no indications that it belonged to the specimen
previously found; and it was regarded as another relic of some one
of the colossal animals whose bones were distributed in the Wealden
deposits. Teeth, fragments of bones, and other fossils were from
time to time obtained from the same quarry; and among these a huge
quadrangular fragment of bone, similar to the enormous mass that had so
long been in my possession, and had defied all attempts to ascertain
its character.[718] It was some time before it occurred to me, that
the three portions of unknown colossal bone might belong to the same
specimen; but eventually they were found to correspond, and upon
cementing them together, the femur of the Iguanodon was, for the first
time, developed.
[718] The fragment alluded to is figured, _Foss. Til. For._ pl. xviii.
The figures in _Lign. 206_ will assist the collector in recognising
the different vertebral processes, even when occurring as detached
fragments. When specimens are evidently rolled or water-worn, there
is, of course, no probability that the corresponding portions will be
met with. Every fragment of a bone the nature of which is not obvious
should be carefully preserved; for sooner or later its characters may
be ascertained. It is scarcely necessary again to remind the collector,
that search should be made for indications of the soft parts around the
bones; the specimen of the paddle of the Ichthyosaurus (_Lign. 215_, p.
669), with its integument, must have impressed this fact too strongly
on the mind to be soon forgotten. If the impression of the extremities
of a bone, of which a fragment only remains, be observed, the block of
stone should be preserved, as a cast may be taken, and the entire form
of the original be ascertained.
BRITISH LOCALITIES OF FOSSIL REPTILES.
Aust Cliff, near Bristol. _Lias._ Plesiosaurus.
Barrow-on-Soar. _Lias._ Ichthyosaurus, Plesiosaurus.
Bath. _Lias._ Plesiosaurus.
Battle, Sussex. _Wealden._ Iguanodon, Cetiosaurus, Goniopholis,
Chelonians.
Binstead, Isle of Wight. _Upper Eocene._ Fresh-water Tortoises.
Bognor. Lower Eocene. Chelone.
Bolney, Sussex. _Wealden._ Hylæosaurus, Iguanodon, Chelonia,
Goniopholis.
Bracklesham Bay. _Middle Eocene._ Crocodiles, Serpents, Chelonians.
Brighton. Chalk. Vertebra of Mosasaurus or Leiodon.
Bristol. _Lias._ Ichthyosaurus.
Brook-Point, Isle of Wight. _Wealden._ Iguanodon, Cetiosaurus, &c.
Burham, near Maidstone. _Chalk._ Chelone, Dolichosaurus,
Pterodactylus.
Bur wash, Sussex. _Wealden_; quarries in the neighbourhood.
Goniopholis, Turtles.
Cambridge. _Lower Chalk._ Raphiosaurus, Polyptychodon. Charmouth.
Lias. Ichthyosaurus.
Charmouth. _Lias._ Ichthyosaurus.
Cheltenham. _Lias._ Ichthyosaurus.
Chipping Norton. _Oolite._ Streptospondylus.
Clayton. _Chalk._ Coniosaurus.
Corncockle Muir, Dumfries. _New Red._ Imprints of feet of Reptiles.
Coton-End, Warwickshire. _New Red._ Labyrinthodon, &c.
Cubbington, Warwickshire. _New Red._ Labyrinthodon.
Cuckfield. _Wealden_; quarries in the vicinity. Iguanodon,
Pelorosaurus, Hylæosaurus, Trionyx, &c.
Culver Cliff, Isle of Wight. _Wealden._ Streptospondylus.
Dover. _Chalk._ Ichthyosaurus, Plesiosaurus.
Garsington, Oxfordshire. _Oolite._ Cetiosaurus.
Glastonbury. _Lias._ Ichthyosaurus.
Grinsill, Warwickshire. _New Red._ Rhynchosaurus.
Guy’s Cliff, Warwick. _New Red._ Labyrinthodon.
Harwich. _London Clay._ Chelonia.
Hastings. _Wealden._ Iguanodon, Pelorosaurus, Goniopholis, Turtles.
Heddington, Oxfordshire. _Kimmeridge Clay._ Pliosaurus.
Hordwell. _Middle Eocene._ Crocodiles, Chelonians, Serpents.
Horsham, Sussex. _Wealden_; quarries in the vicinity. Hylæosaurus,
Iguanodon, Goniopholis, Turtles, &c.
Ilminster. _Upper Lias._ Ichthyosaurus, Teleosaurus.
Kyson, Suffolk. _Eocene._ Serpent, Lizard.
Leamington. _New Red._ Labyrinthodon.
Lewes. _Chalk._ Vertebra; of Mosasaurus or Leiodon.
Lyme Regis. _Lias._ Pterodactyles, Ichthyosauri, and Plesiosauri in
abundance.
Maidstone. _Lower Green Sand_; quarries near the town; particularly
Mr. Bensted’s "_Iguanodon quarry_." Iguanodon, Plesiosaurus,
Polyptychodon, Fresh-water Tortoise.
Malton. _Oolite._ Megalosaurus.
Market Rasen. _Kimmeridge Clay._ Pliosaurus.
Norfolk? _Chalk._ Leiodon: very rare.
Portland, Isle of. _Oolite._ Turtles.
Purbeck, Isle of. _Purbeck._ Goniopholis, Chelonians. _Kim. Clay._
Pliosaurus.
Redland, near Bristol. _Magnesian Conglomerate._ Palæosaurus,
Thecodontosaurus.
Saltwick. _Lias._ Teleosaurus.
Sheppey, Isle of. _London Clay._ Turtles, Serpents, Crocodiles.
Shotover, near Oxford. _Kimmeridge Clay._ Pliosaurus, Teleosaurus.
Southerham. _Chalk._ Mosasaurus, Plesiosaurus.
Stonesfield. _Oolite._ Megalosaurus, Teleosaurus, Pterodactyles.
Stourton, Cheshire. _New Red._ Foot-prints of reptiles
(Cheirotherium), &c.
Street, Somersetshire. _Lias._ Ichthyosauri and Plesiosauri.
Swanage, Isle of Purbeck. Goniopholis, Chelonians.
Tilgate Forest. _Wealden_; quarries in various localities. Iguanodon,
Megalosaurus, Hylæosaurus, Suchosaurus, Turtles, and Tortoises.
Watchett, Somersetshire. _Lias._ Plesiosauri, Ichthyosauri.
Warwick, Guy’s Cliff, near. _New Red._ Labyrinthodon.
Westbrook, Wilts. _Kimmeridge Clay._ Ichthyosaurus.
Weston, near Bath. _Lias._ Plesiosaurus.
Whitby, Yorkshire. _Lias._ Ichthyosauri, Plesiosauri, Teleosaurus.
Wight, Isle of; along the southern shore, near Brook-Point.
_Wealden._ Iguanodon, Cetiosaurus, &c., washed up on the sea-shore.
CHAPTER XVIII.
ORNITHOLITES; OR FOSSIL BIRDS.
Excepting in strata of comparatively modern origin, the remains of
Birds are of extreme rarity in a fossil state. In the caverns that
contain the skeletons of carnivorous animals, and which in many
cases were once their dens, the bones of several species of existing
genera of Birds have been discovered, in England, on the Continent,
in America, and in Australia; and recently there have been obtained
from alluvial deposits in New Zealand the skeletons of Birds, some
of enormous magnitude, and under conditions which leave some doubt
whether, like the _Dodo_, the species may not have been extirpated by
man during the last few centuries; or even if some stray individuals of
the race may not, according to the belief of the aborigines, be still,
in existence in the interior of the country.
From the gypsum quarries at Montmartre, near Paris, Baron Cuvier
obtained several species of Ornitholites; and Prof. Owen has described
the relics of three or four species from the London Clay: these fossil
birds of the eocene tertiary deposits are the most ancient relics
of this class known to the geologist, with the exception of the
foot-prints on the _New Red_ sandstone of North America, that have been
referred to animals of this class.
The rarity of the remains of Birds may probably in some measure
be attributable, as Sir C. Lyell has suggested, to the peculiar
organization of these animals; for their power of flight necessarily
renders them less liable to be engulphed and imbedded in the deltas of
rivers or in the bed of the ocean, than quadrupeds; and the lightness
of their structure, occasioned by their tubular bones and feathery
dermal integument, generally prevents the sinking of the bodies of such
as die on, or fall into, the water; so that their carcases are devoured
or decomposed.
In illustration of this subject, I purpose, in the _first_ place, to
explain such peculiarities in the osteology of the animals of this
class, as may assist the collector in the identification of their
fossil remains; _secondly_, to take a cursory survey of the geological
distribution of fossil Birds, and examine a few of the most interesting
examples; and _lastly_, consider the striking phenomena presented
by the foot-prints of supposed Birds on the strata of those ancient
deposits which are comprised in the _Trias_ or New Red formation.
[Sidenote: OSTEOLOGY OF BIRDS.]
I. Osteological Characters.--The skull in adult birds presents this
remarkable feature, that it is composed of but one bone without any
trace of suture: the osseous tissue is very compact; the bone is
white, and very smooth externally. The lower jaw is formed, as in
reptiles, of several bones, namely, articular, angular, supra-angular,
and dental; it is united to the skull by the intervention of a bone
(_os quadratum_), as in certain reptiles. Both jaws are destitute of
teeth, and are protected by dense horny sheaths, which form powerful
dentary organs. The vertebral column of the neck is exceedingly
flexible, and is composed of a greater number of bones than in any
other living animals; for the cervical vertebæ, which in the mammalia
amount to seven, in birds vary from ten to twenty-four, as in the
Swan. To admit of this extreme mobility of the neck without injury to
the enclosed spinal cord, the annular part, or neural arch, of each
cervical vertebra is enlarged at the extremities that form a junction
with the corresponding bones; thus presenting a modification of
vertebral development directly the reverse of that possessed by the
extinct saurian of the Magnesian conglomerate (see p. 714). The dorsal
and sacra vertebral, on the contrary, are firmly interlocked, and
often anchylosed together, and constitute a strong, inflexible pillar
to afford a fixed point of support to the powerful locomotive organs
of flight. There are no _lumbar_, or rib-less vertebræ. The sacrum
often consists of eighteen, twenty, or more vertebræ, anchylosed into
a solid bone. In the young Ostrich the vertebræ may be found separate
and distinct; and the neural arch is shifted to the union of two
vertebræ, as in the _Megalosaurus_. The sacral spinal cord is almost
as large as the brain; to supply the large muscles. The foramina for
the passage of the nerves are double, one for the sensitive, and the
other for the motive root, which pass out separately and unite in. a
ganglion externally. The ribs are formed so as to combine strength with
lightness in the construction of the walls of the chest, for each rib
has a _recurrent apophysis_, or process, that extends backwards, and
glides over the contiguous bone; this is a very peculiar and obvious
character.[719] The ribs are united in front to the sternum by bony
processes, analogous to the _costal-arcs_ of the Plesiosaurus. The
pectoral arch is distinguished by the prominent longitudinal keel or
crest of the sternum; a structure designed to give attachment to the
powerful pectoral muscles which move the wings, and which presents
characteristic modifications in the different orders; and by the
peculiar bone, termed the _furcula_, or merry-thought, which connects
the clavicles. The clavicles are strongest and most open in birds of
strongest flight. The coracoids (in birds) relate to respiration, and
serve to admit of contraction and expansion of the sternum and abdomen.
The bones of the anterior extremities are modified to adapt these
instruments for the purposes of flight, and those of the fore-arm
(_radius_ and _ulna_) are very long, and firmly united together; the
ulna has a row of slight eminences for the attachment of the quills
of the secondary feathers. The wrist, or _carpus_, is composed of but
two bones, articulated to the radius and ulna, and which admit only
of a _lateral_ movement, by which the wings are folded close to the
body. The bones of the hinder extremities consist of the thigh or
_femur_;[720] the leg-bones, _tibia_[721] and _fibula_, the latter very
small and anchylosed to the former; and of a single shank-bone, which
supplies the place of the tarsal and metatarsal bones of other animals.
This bone is articulated at its upper extremity to the tibia, and
terminates at the lower end in distinct processes, which correspond in
number with the toes; each process having a groove for the pulley-like
tendon that moves the corresponding toe. This construction is peculiar
to birds; for although in some quadrupeds, as the horse for example,
the metatarsus consists of but one piece, the tarsus is composed of
several bones.
[719] In very old crocodiles an analogous apophysis, which is
generally cartilaginous, is sometimes found, ossified (_Owen_).
[720] The acetabulum, or socket for the head of the thigh-bone, is
always perforated. The femur has a surface for the articulation of
the fibula; and by this character the femur of all birds may be
distinguished. There is always a _patella_.
[721] The lower end of the tibia is very like that of the femur.
The toes of birds present deviations equally recognisable; for the
number of the articulations (or _phalangeal_ pieces of bone) in each
toe is different. Thus the thumb, or short toe, has _two_ bones; the
first toe on the inner side _three_; the the middle toe _four_; and
the outer toe _five_. In general, three toes are directed forwards,
and one backwards. In some species, the thumb or opposable toe is
altogether wanting; in others, as in the swallow, it is directed
forwards; in climbing birds, both the outer and the back toe are
situated behind. The position of the hind toe, therefore, affords an
important indication of the habits of the bird (see _Wond._ p. 146,
_Lign. 23_), and from a fragment of the lower extremity of the shank
or tarso-metatarsal bone, with any trace of this articulation, we may
determine whether the individual to which it belonged was a climber,
wader, &c. In the toes of Crocodiles alone, the number of joints is
the same as in birds; but in these reptiles, each toe is supported
by a distinct metatarsal bone. The osteological peculiarities above
enumerated may assist the collector in arriving at some general
inferences as to the nature of any fossil remains of birds.
[Sidenote: FOSSIL BIRDS.]
II. Ornitholites, or Fossil Birds.--The fossil remains of birds consist
in general of their osseous skeletons, and of detached bones, and
rarely of the feathers and eggs.
Pleistocene Epoch.--Bones of the Dodo[722] (see _Wond._ p. 131), a bird
which appears to have become extinct by human agency within the last
two centuries, have been found, associated with the remains of a recent
species of Tortoise, beneath a bed of lava in the Isle of France. And
in some caverns in the island of Rodriguez, the bones of one or more
large birds allied to the Dodo have also been discovered.
[722] See Penny Cyclopædia, _Art._ Dodo, and the beautiful work on the
natural history of the Dodo and its Kindred, by the late lamented Mr.
Strickland and Dr. Melville, 4to.
Dinornis (_fearfully great bird_). _Pict. Atlas_, frontispiece, and p.
172--Numerous bones of large extinct birds have been obtained in New
Zealand by Mr. Rule, the Rev. W. Williams, Col. Wakefield, Mr. Walter
Mantell, and others. These have been referred by Professor Owen to
tridactylous struthious birds (one of which was one-third larger than
the African ostrich), resembling the living _Apteryx_ of New Zealand
(_Wond._ p. 128, _Petrif._ p. 106) in the proportions of the tibia to the
metatarsus, and also in the rudimental state of the wings. The bones
are found in the recent alluvium, but probably in some cases at least
they have been washed by the streams from older alluvial deposits.
An account of the history of the discovery of the gigantic Moa’s bones
in New Zealand (_Wond._ p. 129) is given in full in _Petrif._ p. 93,
_et seq._; and the scientific description of the various parts of
the skeleton of the Dinornis and Palapteryx, chiefly collected from
Professor Owen’s elaborate and finely illustrated memoirs in the
Transactions of the Zoological Society, should be consulted, _Petrif._
p. 108, &c. Of _Dinornis_ Professor Owen discriminates seven or eight
species; of _Palapteryx_, three species; and indications of a species
of a third associated genus, Aptornis.
Fragments of egg-shell accompany these interesting relics of birds
from New Zealand. From Madagascar also bird-bones and eggs have
been obtained in a fossil state, that indicate the original bird
(_Æpyornis_) to have been even of a greater size than the Dinornis.
Ornitholites of the Caverns.--Many limestone districts abound in
fissures and caves, which vary in extent from more superficial hollows
to deep excavations and caverns of considerable magnitude (_Wond._ p.
175, &c.) Beneath the stalagmitic or sparry floors of some of these
caverns, the bones of extinct species of Cats, Bears, and Hyænas, occur
in immense quantities; but the full consideration of these phenomena
will be reserved for the next chapter. The skeletons and detached bones
of several kinds of Birds are often found imbedded with these remains;
and under circumstances which seem to indicate that they were brought
into these caverns as prey by the carnivora, with whose relics they are
now associated. Some examples show that the birds had fallen into the
fissure; others, that their bones had been transported to their present
situation by the action of water.
In the Cave of Kirkdale, in Yorkshire (_Wond._ p. 179), Dr. Buckland
found bones of the Raven, Lark, Pigeon, Duck, and others; and as almost
all the specimens were the remains of wing-bones, it is considered
probable that they are the relics of dead birds, which had been brought
into the cave by the hyænas, whose den it is supposed to have been for
a considerable period (_Reliquiæ Diluvianæ_, p. 34).
Similar remains have been discovered in the Kent’s Hole cavern, and in
that at Berry Head, Torbay; from the latter Professor Owen has obtained
the wing-bones of a Falcon (_Brit. Fos. Mam. and Birds_, p. 558).
In France, the Lunel-Viel caverns have yielded a few bird-bones; and
many such remains occur in the caves of Brazil, described by M. Lund.
The so-called "bone-breccia" of the coasts and islands of the
Mediterranean (_Wond._ p. 185) contains frequent remains of birds: they
have been especially noticed at Cette, Nice, Sardinia, and Gibraltar.
In the deposits especially referred to the northern drift or
Boulder-clay period, fossil birds appear to be very rare, although the
remains of vertebrate terrestrial animals are locally abundant. Dr.
Buckland states that some bones, apparently of a species of goose,
found at Lawford, with the remains of Hyæna, Elephant, Rhinoceros, &c.,
is the only instance he has met with of fossil birds in the drift of
England (_Reliq. Diluv._ p. 27).
On the Continent, bird-bones have been found, at Quedlingbourg,
Meissen, and in the Lahn Valley, in deposits said to be of this age.
Ornitholites of the older Tertiary Deposits. (_Lign. 246._)--The
very rich pliocene deposits at Œningen (p. 559) have afforded a few
fragments of birds’ bones.
Three or four species of Ornitholites (Duck, Heron, Flamingo, &c.),
and several examples of the eggs of birds, have been discovered in
the lacustrine strata of Auvergne. Birds’ bones also occur in the
fresh-water limestone near Issoire, in the Buy de Dôme, associated
with the remains of eocene mammalia. In Germany, bird-bones have been
found in tertiary deposits at Wiesbaden, Wiesnau, and Mornbach. In
the Siwalik Hills the remains of birds are associated with the fossil
reptilia and mammalia, to which reference has already been made (p.
731).
From the quarries of gypseous limestone of Montmartre, near Paris,
Baron Cuvier obtained many bones, and some connected portions of the
skeletons of several birds related to the Pelican, Sea-lark, Curlew,
Woodcock, Owl, Buzzard, and Quail.[723] In several of these examples
there are the imprints and remains of the quills and feathers; in some
the skeleton has perished, and a pellicle of dark-brown substance, with
the configuration of the original, alone remains (see _Lign. 246_).
These Ornitholites are associated with the bones of the Palæotheria,
and other extinct mammalia of the eocene period. Two or three
Ornitholites have been discovered at Montmartre, in which almost the
entire skeleton is preserved. In one example, described by Cuvier,
the remains of a bird are displayed in such a manner as to render it
probable that the animal had fallen on its belly, and become partially
impacted in the surface of the soft gypsum, which is now become solid
stone; and that, previously to its being completely enveloped, the
principal part of its head and the left leg were removed either by
some voracious animal, or by the action of the water. In addition to
the other parts of the skeleton, the under side of the bill is very
distinctly impressed on the stone, and the left branch is entire; there
are also the remains of the cellular basis of the skull; and both the
wings are well preserved. Nine or ten species of fossil birds were
identified by Cuvier from the Paris eocene strata.
[723] Ossemens Fossiles, tom. iii. p. 302, plates lxxii.--lxxv.
[Sidenote: FOSSIL VULTURE.]
[Illustration: Lign. 246. Fossil Bird.
_Eocene._ _Montmartre._
(Cuvier, _Oss. Foss._ vol. iii. p. 318, pl. lxxiii. _fig._ 2.)
The remains of this individual consist only of a thin brown pellicle,
indicating the form and proportions of the head, body, and limbs.]
Lithornis vulturinus. _Geol. Trans._ 2d series, vol. vi. p. 206, pl.
xxi. figs. 5 and 6.--Under the name of Lithornis (_petrified-bird_),
Professor Owen has described the fossil remains of a bird, consisting
of two most characteristic bones,--the sternum and sacrum,--and
fragments of other bones, obtained from the London Clay of the Isle of
Sheppey. These relics present a close agreement with the corresponding
bones of the Vulture tribe, but indicate a smaller species of Vulture
than any now known to exist.
In his "History of British Fossil Mammalia and Birds," 1846, Professor
Owen has also described another sacrum from the Sheppey Clay, a
_sternum_ from Primrose Hill, and the _cranium_ of a bird, probably
of the _Halcyonidæ_ family, from the same eocene deposit at Sheppey.
This has also yielded a portion of shank-bone, which, according to Mr.
Bowerbank, indicates a bird of the size of a full-grown albatross.
Brit. Assoc. 1851.
Some few specimens of cylindrical bones from the Chalk and the
Wealden[724] have been previously referred to Birds, and described
as remains of species of that family. These fossils, however, have
lately been reexamined in comparison with more perfect bones of similar
character; and, with the exception of a few, the structure of which
decidedly has the characters belonging to bird’s bone, the result of
this investigation has assigned them to Pterodactyles.[725] The long
thin cylindrical bones from the Stonesfield Oolite are probably all
Pterodactylian also, as suggested by the late Mr. Miller.
[724] One fragment of a bone, apparently of an _ulna_, retained a row
of small eminences, probably the points of attachment for the quills of
the secondary feathers of the wings. This specimen would appear to have
a decided reference to ornithic structure, but it was transferred to
the British Museum, and is not now to be seen.
[725] See _Quart. Geol. Journ._ vol. ii. p. 96, &c.; and Owen’s
_Monograph on Chalk Reptiles_, 1851, p. 80, _et seq._ It is to be
hoped that the eminent microscopists, Mr. Bowerbank and Professor
Quekett, may be enabled before long to elucidate the intimate structure
of pterodactylian bone; which, although of an essentially reptilian
type, has characters of its own, offering some resemblances to
bird-structure, that have not yet been fully described. Some specimens
of bones from the Wealden (for instance, the specimen figured in
_Geol. Trans._ 2d ser. vol. v. pl. xiii. _fig._ 6, and _Geol. Journ._
vol. iv. pl. i. _fig._ 9,) exhibit under the microscope an intimate
structure resembling that seen in bird-bone, in contradistinction
to that characteristic of reptilian bone. But until we are better
acquainted with the microscopic structure of the osseous tissue of
the Pterosaurians, and are in possession of more perfect specimens of
bones, it cannot be satisfactorily determined to what extent the class
of Birds existed in the country of the Iguanodon.
[Sidenote: ORNITHOIDICHNITES.]
III. Ornithoidichnites. (_Bird-like foot-prints._) _Ligns._ 247, 248.
_Bd._ pl. xxvi. _a_, xxvi._b_.--The palæontological history of the
class of birds, as evidenced by the foregoing pages, is carried back
but to a comparatively recent era in the earth’s history: and indeed,
in the present state of our knowledge, it may be said that all positive
evidence of the former existence of this highly organized class of
vertebrated animals is confined to the Tertiary and Wealden deposits.
A most interesting discovery, however, by Dr. James Deane,[726] of
Greenfield, U. S. seems to prove that numerous bird-like bipeds,
and some of gigantic size, existed at the period when the Triassic
or _New Red_ strata were in the progress of formation; that period,
as the reader will remember, in which the Labyrinthodonts and other
extraordinary reptiles flourished. _Rep. Brit. Assoc._ 1841, p. 230,
note.
[726] See "Illustrations of Fossil Foot-prints of the Valley of the
Connecticut," 1849, 4to. with nine plates.
In certain localities of the New Red sandstone in the valley of the
Connecticut, numerous tridactyle markings had been occasionally
observed on the surfaces of the slabs of stone when split asunder,
in like manner as the ripple-marks appear on the successive layers
of sandstone in Corncockle Muir, Tilgate Forest, &c. Some remarkable
distinct impressions of this kind at Turner’s Falls (Massachusetts)
happening to attract the attention of Dr. Deane, that sagacious
observer was struck with their resemblance to the foot-marks left
on the mud-banks of the adjacent river by the aquatic birds which
had recently frequented the spot. The conviction that the imprints
on the stone were referable to a similar origin with those on the
mud was so strongly impressed on his mind, that he immediately
collected a series of specimens, and communicated his discovery and
opinion to Professor E. Hitchcock, who followed up the inquiry with
a zeal and success that have led to the most interesting results.
No reasonable doubt now exists that the imprints in question have
been produced by the tracks of bipeds, impressed on the stone when
in a soft state. The announcement of this extraordinary phenomenon
was first made by Professor Hitchcock, in the American Journal of
Science (January, 1836); and that eminent geologist has subsequently
published full descriptions of the different species of imprints
which he has detected, with excellent lithographs, in his "Geology of
Massachusetts." (See _Petrif._ pp. 64-73.)
Three highly interesting specimens of the Ornithoidichnites of North
America, collected and developed by Dr. James Deane, have been lately
added to the collection of organic remains in the British Museum. They
exhibit several varieties of the foot-prints, and are in a very fine
state of preservation. The surface of the largest slab is eight feet
by six, and bears upwards of seventy distinct impressions, disposed
in several tracks, as shown in the _Lign. 247_. The direction and
disposition of the foot-tracks are rendered more distinct by the lines
drawn from one imprint to another in the consecutive series.
The principal tracks on this slab, _Lign. 247_, are as follow;
Fig. 1 to 1, directed from below upwards, is a track consisting of six
large footsteps.
2 to 2, from above downwards; a track of four foot-prints, disposed
almost in a right line, and very far apart.
3 to 3, a track of five foot-prints, from above downwards, of a
large, heavy animal, like fig. 1.
4 to 4, from above downwards, four foot-prints like _fig._ 2,
disposed in a nearly straight track, and far apart.
5, a track of five heavy foot-prints, directed obliquely
upwards.
6 to 6, five foot-prints of a large biped, in a track from below
upwards.
7, a series of five delicate foot-prints.
8 to 8, a track of eleven very small foot-prints, disposed in
zigzag, and extending obliquely from the right extremity
to the upper edge of the slab.
9 to 9, a track of four large and distant foot-prints, passing
obliquely across the stone from left to right.
I subjoin also a representation of one of the smaller foot-prints, of
the natural size, the surface of the stone being sprinkled also with
hemispherical markings produced by drops of rain. (_Lign. 248._)
A Slab of New Red Sandstone (_eight feet by six_), from Turner’s Falls,
Massachusetts, United States, covered with numerous Foot-marks of
Bipeds; indicating the Tracks of ten or twelve individuals, of various
sizes. Discovered by _Dr. James Deane_, of Greenfield, Massachusetts.
This Specimen is now in the British Museum.--(_From the American
Journal of Science_, vol. xlvi. p. 73.)
[Illustration: Lign. 247. Ornithoidichnites, or Imprints of the
Footsteps of Bipeds with Bird-like Feet, on Sandstone.
_To face_ p. 770.]
[Sidenote: ORNITHOIDICHNITES.]
The above will suffice to give the reader a general idea of the nature
of these extraordinary impressions. A few shapeless fragments of
bones are the only vestiges of the skeletons of any animals, with the
exception of fishes, that have been found in the strata which have
furnished the slabs of Ornithoidichnites. Some Coprolites also have
been discovered.
[Illustration: Lign. 248. Bird-like Footprint, and impressions of
Rain-drops, on Sandstone (_nat._). _New Red Formation; Massachusetts._
[Amer. Journ. of Science, (1843,) vol. xlvi. p. 73.]]
The enormous size of some of the foot-marks is calculated to excite
great surprise. I have in my possession (through the kindness of Dr.
Deane) imprints that prove the size of the foot to have been fifteen
inches in length, and ten inches in width, exclusive of the hind
claw, which is present in some species, and is here two inches long.
The foot-prints of this biped when in a consecutive series of five
or six, are from four to six feet apart; which, of course, must have
been the length of the stride; the longest stride was probably made
by the animal when running; the shortest, when walking at a moderate
pace. These footsteps indicate proportions so far exceeding those
of all known living bipeds,--for the foot of the African ostrich is
but ten inches long,--that the geologist may be pardoned for having
hesitated to adopt the opinions of the American savans, in the absence
of any relics of the osseous structure of the supposed birds; although
sanctioned by the high authority of Dr. Buckland, who, from the first,
concurred in the views of Professor Hitchcock (_Bd._ ii. p. 39): but
this objection has been in a great measure removed by the discovery of
the remains of the gigantic Moa or Dinornis of New Zealand, with feet
equal in magnitude to the largest of the Connecticut foot-prints. See
p. 763, and _Pict. Atlas_, frontispiece. Professor Hitchcock is of
opinion that upwards of forty species of these biped foot-prints may be
distinguished. Foot-prints referable to chelonians, batrachians, and
lizards are associated with the above.[727]
[727] Trans. Amer. Phil. Soc. n. s. vol. x. pt. ii. p. 312.
In the New Red Sandstone of Stourton Hill, near Liverpool, Mr.
Cunningham has observed tridactylous, webbed foot-prints,[728] 2-1/2
inches long, which he refers to a bird; Mr. Hawkshaw also noticed
some bird-like tracks at Lymm; and Professor Harkness met with a trace
of a biped at Weston Point, near Runcorn. These appear to be the only
indications of ornithoidichnites in the Trias of England; and these are
very obscure.
[728] These are accompanied by cheirotherian prints, and by the
cast of an impression quite similar to that made on the sands of the
sea-beach of to day, by the Medusa (sea-nettle or jelly-fish) left by
the reflux of the tide and exposed to a few hours of sunshine. Mr.
Cunningham and Mr. Pidgeon have furnished a figure of this interesting
impression of the "jelly-fish," which has left "the solid memorial of
its evanescent existence en the ancient strand" of the Triassic sea,
showing that the physical conditions of land, water, and atmosphere
were the same then as those that now obtain.--_Liverpool Lit. Phil.
Soc. Proc._ 1848, p. 128, _fig._ 1. A similar imprint on a Jurassic
rock in Germany is referred to at p. 280.
In the Wealden of Hastings and the Isle of Wight, the natural casts of
large tridactylous foot-prints have been observed by Mr. Taggart and
Mr. Beckles (see _Quart. Journ. Geol. Soc._ vol. ii. p. 267, vol. vii.
p. 117, vol. viii. p. 396, and _Geol. Isle of Wight_, p. 328), but as
yet no solution of the mystery at present enwrapping these gigantic,
tridactylous, biped (?) ichnolites has presented itself: we only know
that the creature that left them traversed the borders of the mighty
river which floated down the bulky carcases of the Hylæosaur and
Iguanodon.
[Sidenote: ON COLLECTING FOSSIL BIRDS.]
On Collecting the Fossil Remains of Birds.--Notwithstanding the extreme
rarity of fossils of this class, the student should not be discouraged
in his search for the remains of Birds in the secondary rocks. That
far more instructive specimens than any that have fallen under my
observation may be discovered in the Wealden strata by diligent
research, there can be no reasonable doubt. It is also very probable
that the Stonesfield slate, which abounds in remains of terrestrial
plants and animals, will be found to contain Ornitholites. It is
important for the collector to bear in mind, that when only a fragment
of the shaft of a bone remains imbedded in the stone, if the imprint
of the other portions be preserved, he may obtain a knowledge of the
form of the extremities; in the same manner as the external markings
of the surface of a shell may be ascertained, when the shell itself is
lost or destroyed, and a smooth stony cast of the internal cavity only
is left. The same remark will apply to the bones of reptiles and other
animals; for example, a perfect leg-bone may be imbedded in a block of
limestone; but, when exposed by breaking the stone, a portion of the
shaft may alone remain attached, and both extremities be shattered to
pieces by the concussion of the blow; yet, if the impression remains,
the entire form of the original may be determined.
The _foot-prints_, not only of birds, but of reptiles and other animals,
should be diligently sought for on the surfaces of laminated strata of
sand and clay, and especially where the presence of ripple-marks, and
the impressions of rain-drops, indicate that the beds were deposited in
shallow water. The forest-marble flags at Castle Comb, north of Bath,
the Stonesfield slates, and the sandstones around Horsham (in Sussex),
and particularly at Stammerham (see _Geol. S. E._ p. 213), are often
rippled, and it is therefore probable that the foot-prints of some of
the Oolitic and Wealden quadrupeds and bipeds, if such existed, will
sooner or later be discovered.
CHAPTER XIX.
FOSSIL MAMMALIA.
The remains of Mammalia discovered in a fossil state include an immense
number of species, and furnish examples of almost every living genus,
and of numerous genera, and even orders, of which no existing species
are known. Yet amidst the vast accumulations of the skeletons of the
higher orders of vertebrata contained in the tertiary deposits, and in
the superficial drift, belonging to species which have successively
appeared on the surface of our planet, flourished for indefinite
periods of time, and then become annihilated, no vestiges of Man, or
of his works, have been detected. Human skeletons, naturally imbedded,
have hitherto only been observed in the silt of modern alluvial
plains,[729] in peat-bogs (_Wond._ p. 64), and in conglomerates
of recent date, such as are in the progress of formation on the
sea-shores, particularly where the water is loaded with the detritus of
shells and corals, and the waves transport the calcareous matter along
the margins of creeks and bays, or deposit it in the shallows along the
coast (see _Wond._ p. 87, and _Petrif._ p. 483).
[729] There seems, however, reason to believe that the human skulls
and bones found with elephantine and other remains in the Alps of
Swabia, are of contemporaneous origin with these extinct mammals. (See
_Literary Gazette_, 1853, p. 1027.)
The geological distribution of fossil mammalia,[730]--the occurrence of
the entire carcases of extinct species of Elephant and Rhinoceros in
blocks of ice (_Wond._ p. 151),--of recent species in the superficial
alluvial clay and silt,--of recent and extinct forms in the Drift or
Pleistocene deposits (_Wond._ p. 147),--of the gradual preponderance
of unknown species and genera, in proportion as we carry back our
retrospect to the most ancient Tertiary strata (_Wond._ p. 254),
--the sudden disappearance of all vestiges of the entire Class of
Mammalia, with the last bed of the Eocene deposits,--with the exception
of a few minute jaws in one set of beds of the Oolite in England
(_Wond._ p. 510), and of a few teeth in the Trias (?) of Germany,[731]
the sole records of the existence of any of the highest types of
animal organization throughout the vast periods of the secondary
formations--are so fully treated of in the _Wonders of Geology_, that I
need not dwell upon the subject in the present volumes. Neither is it
desirable to enter at large upon this department of Palæontology, for
it were vain to attempt the elucidation of the anatomical characters
of but one extinct species of Mammalia, without giving details of
structure, that could only be successfully demonstrated in a work
expressly devoted to the subject. Referring, therefore, to Cuvier’s
_Ossemens Fossiles_, and to Professor Owen’s "_History of the British
Fossil Mammalia_," 8vo. 1846, I must limit my remarks on the Fossil
Mammalia to a brief summary of modern discoveries, with suggestions for
the identification and collection of some of the most interesting or
prevalent remains.
[730] For a notice of the distribution of mammalian remains in the
Upper Tertiaries of Europe, see Phillips’s _Geology_, 1853, vol. i. p.
45, &c.
[731] For an account of these teeth of small insectivorous mammals from
the "bone-bed" of Würtemberg, which has an analogous position at the
top of the Trias with the "bone-bed" of Axmouth and Aust Cliff, see
_Ly._ p. xiv. figs. 529-531.
The fossil remains of Mammalia will be considered under the following
heads:--
I. Cetacea, or animals of the _Whale tribe_.
II. Ruminantia; including the _Camel_, _Giraffe_, _Deer_,
_Sheep_, _Ox_, &c.
III. Pachydermata; comprising the _Proboscideans_, as the
_Elephant_, and the ordinary _Pachyderms_, as the
_Rhinoceros_, _Horse_, _Swine_, &c.
IV. Edentata: animals without teeth, or with only
molars, as the _Ant-eater_, _Sloth_, _Megatherium_, _Mylodon_,
&c.
V. Rodentia, or Gnawers; as the _Hare_, _Beaver_, _Rat_, &c.
VI. Marsupialia; animals with an abdominal pouch, as
the _Kangaroo_, _Opossum_, &c.
VII. Carnivora; including the _Bats_, _Moles_, and the carnivorous
tribes in general.
VIII. Quadrumana; _Apes_ and _Monkeys_.
IX. Bimana; or _Man_.
[Sidenote: FOSSIL WHALES.]
I. Fossil Cetacea.[732]--The _Cetaceans_, although popularly termed
fishes, are as perfect air-breathing vertebrated animals, as the
terrestrial mammalia, and, like them, give suck to their young. Instead
of fore-feet or arms, they have a pair of fins or paddles, but are
destitute of hinder extremities, the place of the latter organs being
supplied by a powerful cartilaginous horizontal fin, appended to the
tail. The Cetaceans, therefore, differ in this respect from the fossil
marine reptiles, the Ichthyosaurus and Plesiosaurus (see p. 662), which
have two pairs of paddles. This order, as is well known, comprises
the most colossal forms of animal existence,--the Whales. Some are
herbivorous, others carnivorous; many have powerful teeth; others are
edentulous, the jaw being furnished with a series of elongate plates of
the substance familiarly known by the name of _whale-bone_.
[732] _Cetacea_: an order of aquatic mammalia, comprising the W hales,
Narwhals, Porpoises, Dolphins, and Dugongs.
The fossil remains of Cetaceans have, for the most part, been observed
in alluvial silt and beds of drift, in valleys still traversed by
rivers; but many examples have been discovered in elevated sea-beaches,
proving that, although, geologically speaking, these beds are of
modern origin, yet great changes in the relative level of the land and
sea must have taken place since these remains were imbedded. Thus, on
the banks of the river Forth, near Alloa, in Scotland, the skeleton of
a Whale (_Balænoptera_), seventy-two feet long, was discovered imbedded
in clay, twenty feet above the highest tide.[733] Cuvier mentions
the discovery of bones of a _Lamantin_ at Angers; of a Dolphin,
and Rorqual, in Lombardy; and of a Grampus, in the pliocene of the
Sub-Apennines.[734]
[733] Dr. Fleming’s _British Animals_, p. 39.
[734] For notices and descriptions of Cetacean remains found in
England, see Owen’s _Brit. Foss. Mammalia_, p. 516, _et seq._
Otolithes of Cetaceans.--Petro-tympanic bones of several large whales
have been found in great numbers in the red Crag of Felixstow; among
them is one of the genus Physeter, or Sperm-Whale.[735]
[735] Proc. Geol. Soc. for 1845, p. 41; and Brit. Foss. Mam. p. 526, &c.
Brighton Fossil Whale.--An interesting discovery of the anterior half
of one side of the lower jaw of a Whale, undoubtedly coeval with the
extinct Mammoth (_Elephas primigenius_), was made in 1828 in the Cliff,
east of Kemp Town, Brighton, under the following circumstances. On the
face of the Cliff, in the ancient shingle which lies immediately upon
the chalk and is surmounted by beds of calcareous rubble, containing
bones and teeth of Elephants, to the height of one hundred and twenty
feet, some fishermen had observed a huge bone, that had been laid
bare by an unusually high tide and now projected two or three feet
beyond the face of the Cliff. Unable to remove it, they broke off the
extremity, a fragment of which was sent to me. Upon repairing to the
spot a few days afterwards, I found that the fishermen had renewed
their attack, and demolished a considerable portion of the bone in
ineffectual attempts to dislodge it from its bed; and had desisted only
from the apprehension of being buried beneath the overhanging cliff,
which is composed of loosely aggregated materials. Unfortunately,
the bone extended directly into the cliff, and it required several
hours of labour, not unattended with danger, before an excavation was
made sufficiently large to expose the entire specimen. It proved to
be the anterior nine feet of the left branch of the lower jaw of a
whale-bone Whale (_Balæna mysticetus_). It was of a light fawn colour
externally, but the internal coarse osseous structure was delicately
white; it was extremely brittle, and, upon attempting to move it,
broke into a thousand pieces. Time would not permit of the application
of a coating of plaster of Paris, for ere we had completed our task
the tide was rapidly approaching, or this interesting relic might
have been extracted entire. This portion of lower jaw, before it was
mutilated by the fishermen, was twelve feet long, and thirty-six inches
in circumference at the largest extremity. It must have belonged to a
Whale from sixty to seventy feet in length.[736]
[736] The fragments of this jaw that were preserved are now exhibited
in the British Museum, in Room V.
In the fluviatile silt of the valley of the Ouse, near Lewes (_Wond._
p. 63), the skull of a Porpoise and a portion of the cranium, with the
socket of the long straight tooth, of a Narwhal (_Monodon monoceros_),
were found twelve feet beneath the surface of the soil.
The bones of an herbivorous Cetacean, the _Manatus_, a genus now
peculiar to the torrid zone, have been found in the eocene strata in
various parts of France, associated with those of the Palæotheria and
other extinct mammalia of the Paris basin.
[Sidenote: ZEUGLODON.]
Zeuglodon cetoides. _Lign. 249._[737]--The remains of a very remarkable
Cetacean, of an extinct genus, were first made known by Dr. Harlan,
of Philadelphia, who obtained a considerable portion of the jaws with
teeth, vertebræ, and other bones of an animal of enormous size, from
Alabama and Arkansas, United States. These relics were discovered
in tertiary (_eocene_) limestone, associated with a marine shelly
conglomerate, from a cliff near the bed of the river Owachita. When
first observed, the bones extended along the face of the rock, with
intervals between them, to the extent of one hundred feet, and the
animal to which they belonged must have exceeded seventy feet in
length. Dr. Harlan ascribed these bones to an unknown reptile, which
he called Basilosaurus (_king of the lizards_); but a more correct
investigation, by Professor Owen, proved their cetacean character,
and the peculiar form of the worn molar teeth suggested the name of
_Zeuglodon_ (_yoke-tooth_).
[737] Owen, _Geol. Trans._ 2d ser. vol. vi. p. 69, &c., plates vii.
viii. ix.; Harlan’s _Medical and Physical Researches_, p. 337, &c.;
Gibbes, _Journ. Acad. Nat. Sc. Philadelphia_, 2d ser. 1847, vol. i.
pp. 5 and 16; Bulkley, _Silliman's Journal_, vol. xliv. p. 409; Carus,
_Nova Acta Cur. Nat._ vol. xxii. pt. ii. 1848.
[Illustration: Lign. 249.
Zeuglodon cetoides.
Portion of the Jaw, with Teeth, and a Vertebra.
_Eocene._ _Alabama, United Slates._
Fig. 1.--Portion of the Upper Jaw, with three teeth: 1/8 _nat._
_a._ The exposed fang of a tooth.
2.--Transverse section of the base of the crown of a tooth, showing
the deep constriction in the middle: 1/4 _nat._
3.--A caudal vertebra: 1/12 _nat._
]
[Illustration: Lign. 250. Teeth of Zeuglodon: 1/2 _nat._
_Eocene._ _France and N. America._
Fig. 1.--Upper tooth of Z. squalodon; from near Bordeaux.
2.--Molar tooth of Z. cetoides; from Alabama, United States.
3.--Canine tooth of Z. cetoides.
]
The teeth (_Lign. 250_) are of two kinds, some having but one fang, and
others two, implanted in separate sockets and placed obliquely in the
jaw; they are of a compressed, conical form, with an obtuse apex, the
crown being deeply conjugate, or contracted in the middle, as shown
in the transverse section, _Lign. 249, fig. 2_. They are devoid of
enamel, but the dentine is coated with cement, and their structure is
decidedly mammalian; and a microscopical examination, Professor Owen
states, incontestably proves their cetacean character. The longitudinal
diameter of the middle tooth is three inches.
The vertebræ resemble those of the large cetacean known by the name of
_Hyperoodon_; a caudal vertebra is figured _Lign. 249, fig. 3_. The
original animal was related to the Dugong and Cacholot, and appears to
have held an intermediate place between the latter and the herbivorous
species.
[Sidenote: FOSSIL RUMINANTS.]
[Illustration: Lign. 251. Teeth of a Ruminant. _Pleistocene._
_Gibraltar._
Imbedded in a mass of the "osseous breccia."]
II. Fossil Ruminants. (_Owen’s Brit. Foss. Mam._ p. 444, _et
seq._)--The fossil bones of animals of this order are very numerous in
the alluvial deposits, in caves, and in pleistocene deposits, in almost
every part of the world. They are generally associated with the remains
of the next group. The skulls of Oxen, and horns and bones of the Bison
and Auroch, have been found in North Cliff, Yorkshire, at Walton in
Essex, and other parts of England. The fossil oxen appear to have been
one-third larger than the recent species; and the horns are relatively
more massive than in the domestic race; some of the horns measure four
feet across, at the widest expansion. In the immense accumulations of
large mammalia in the tertiary beds of the Sub-Himalayan or Siwalik
range, numerous remains of oxen occur. The teeth of one species are
often found in the Elephant-bed at Brighton.
Of the Deer family the relics of several kinds have been discovered in
Drift and Caverns. The cave of Kirkdale alone contained the remains of
three species.[738] The bones of a species that cannot be distinguished
from the common Bed Deer are found in the modern shell-marls of
Scotland, associated with the remains of oxen, horse, boar, dog, wolf,
and beaver. The bones and antlers of the Reindeer have been found at
Brentford and other places (_Brit. Foss. Mam._ p. 479; and _Rep. Brit.
Assoc._ 1851. Sect. p. 69). The ossiferous caverns, which contain bones
of Carnivora, also yield those of Deer; as the caves of Kirkdale and
Banwell, &c. in England, and the celebrated caverns of Muggendorf, on
the Continent. A species of Musk-deer has been found at Epplesheim; and
bones of deer are associated with those of the Dinotherium, in Rhenish
Hesse, in late Tertiary deposits. The teeth and a lower jaw, with other
bones, of a species of deer, were obtained from the Brighton Elephant
bed (_Wond._ p. 114).
[738] The Rev. Dr. Buckland’s _Reliquiæ Diluvianæ_; or, Observations on
the Organic Remains found in Caves, Fissures, and Gravel; 1 vol. 4to.
1823, pl. viii. and ix.
The most celebrated fossil animal of this family is the Gigantic Stag
or Deer of Ireland (see _Petrif._ p. 455; _Wond._ p. 132), whose bones
and antlers are found in immense quantities in superficial marl, in
Ireland, in the Isle of Man, and occasionally in England. (Geol. Journ.
vol. iv. p. 42.) A skeleton that was found, almost entire, in marl
abounding in fresh-water shells, at the depth of twenty feet, is six
feet high, nine feet long, and nine and a half feet in height, to the
top of the right horn. Some antlers are so large, that the interspace
from one point to the other exceeds twelve feet.[739]
[739] See _Pict. Atlas_, pl. lxxi.; a good figure of the skeleton of
the fossil Irish Deer is given in the Penny Cyclopædia, vol. viii. p.
364; for a detailed account of this gigantic animal, see Owen’s _Foss.
Brit. Mammalia_, p. 444, and _Charlesworth’s Journal_, p. 87.
The Giraffe, the tallest of known quadrupeds, and now restricted to
the deserts of Africa, was once a native of Europe and Asia, for
fossil bones of a species of this remarkable ruminant have been found
at Issoudun, in France, and in the Siwalik mountains, with several
varieties of Elk and Deer.
Of the Camel, the only ruminant with incisor teeth in the upper jaw,
a gigantic species has been discovered by Dr. Falconer and Captain
Cautley, in the Siwalik range.
[Illustration: Lign. 252. Bones of the Feet of Horse, Deer, and
Anoplotherium.]
Fig. 1.--Fore-foot of the Horse.
2. ---- Deer.
3. ---- Anoplotherium gracile.
_m, m._ Metacarpal bones ("canon-bone" in the Horse.)
_s_, in fig. 1, the "splint-bone," or rudimentary metacarpal.
_p, p._ First or proximal phalangeal-bones ("pastern" in the Horse).
_p^2, p^2._ Second phalangeals ("coronet" or "crown-bone" in the Horse).
_u, u._ Unguals, or bones of the hoof ("coffin-bone" in the Horse).
In this category we must notice another most interesting discovery of
the indefatigable and eminent naturalists above mentioned, namely, the
_Sivatherium_ (see _Wond._ p. 163), an extinct animal, which forms,
as it were, a link between the ruminants and the large pachydermata.
The skull has four persistent horns, and was furnished with a nasal
proboscis. The living creature must have resembled an immense Antelope
or Gnu, with a short thick head and an elevated cranium, crested
with two pairs of horns. A splendid specimen of the skull of the
_Sivatherium_ has been placed in the palæontological collection of the
British Museum by Dr. Falconer (_Petrif._ p. 456, _Lign._ 98).
[Sidenote: ELEPHANT. MASTODON.]
III. Pachydermata.[740]--The fossil remains of this order of mammalia
are most abundant, and belong to numerous species, comprising many
extinct genera of a highly interesting character. See Pictet’s
_Paléontologie_, new edit. 1853, vol. i. p. 127, _et seq._
[740] See Owen on the Classification of the Pachydermata, _Quart. Geol.
Journ._ vol. iv. p. 127, &c.
[Illustration: Lign. 253. Elephas Ganesa.
Front view of the Cranium and Tusks. (_The original is 14 feet long._)]
Fossil Elephants and Mastodons. _Lign. 253, 254, 258-260._ _Owen’s
Hist. Brit. Foss. Mam._ p. 217, &c.; _Wond._ pp. 147, 157.--The bones,
teeth, and tusks of Elephants, equal in magnitude to, and distinct from
the existing African and Asiatic species, are scattered throughout the
superficial alluvial and pleistocene accumulations of Europe.
[Illustration: Lign. 254. Mastodon giganteus.
Unworn Molar Tooth: 1/3 _nat. size_.
_Upper Tertiary._ _Banks of the Hudson, N. America._]
The fossil bones and teeth (_Pict. Atlas_, pl. lxxi. lxxiv.) of these
gigantic animals are so abundant, that examples may be found in all the
provincial, and in most private collections; and the British Museum
possesses an unrivalled series of specimens of both groups of these
colossal herbivorous mammalia, namely, the Elephants properly so called
and the Mastodons (_Petrif._ pp. 463, 471). It contains an invaluable
series of specimens from the Siwalik hills, presented by Capt. Cautley
and Dr. Falconer (_Petrif._ p. 469); amongst which are remains in which
the dental organs present every modification of structure, from that
of the mastoid tubercles of the tooth of the Mastodon, to the vertical
laminæ of cement, enamel, and dentine of the Elephant. The Museum also
possesses the entire skeleton of the Mastodon (_Petrif._ _Lign._ 107)
formerly exhibited by M. Koch, as well as the fine suite of jaws and
teeth obtained by the same indefatigable collector. This collection
demonstrates that all the bones and teeth, apparently of several
species, and, as some have supposed, of distinct genera, belong but to
the one grand Mastodon--the _M. giganteus_ of Cuvier; it also clearly
proves that the young mastodon had a pair of tusks placed horizontally
in the lower jaw; and that but one of these tusks became developed in
the adult, and that only in the male.[741]
[741] This remarkable circumstance, in the infancy of palæontological
science, gave rise to a very venial error; it was made to constitute
the character of a new genus, to which the name _Tetracaulodon_ was
applied.
It is therefore unnecessary to enlarge upon this subject, for an
inspection of a few specimens will afford the student a clearer insight
into the structure of the skeletons and teeth of these animals than any
description. The form of the teeth, and the disposition of the dental
elements, are illustrated in _Wond._ p. 143, and _Ly._ p. 159.
[Sidenote: DINOTHERIUM.]
Dinotherium. _Petrif._ p. 474; _Wond._ p. 173; _Bd._ i. p. 135, pl.
ii.--At Epplesheim, forty miles north-east of Darmstadt, in beds of
sand and marl of the median Tertiary formations, the jaws, teeth,
skull, and other remains of the Dinothere, one of the most gigantic of
terrestrial mammalians, have been discovered; they are preserved in the
museum at Darmstadt. The length of the largest species is estimated at
eighteen feet. The teeth had previously been found in France, Bavaria,
and Austria; and, from their close analogy to those of the Tapir, were
described by Cuvier as belonging to an extinct colossal animal of that
genus. But subsequent discoveries have shown that the _Dinotherium_ was
probably a proboscideal animal, and had two large curved tusks directed
downwards in the anterior extremity of the lower jaw.[742]
[742] There are some fine specimens, and good models of the Darmstadt
specimens, in the British Museum (_Petrif._ p. 474).
[Illustration: Lign. 255. Anoplotherium Commune.
_Eocene Tertiary. Montmartre._
Restored outline of the animal; after Cuvier.
(_The original was about the size of an Ass._)]
[Sidenote: CUVIERIAN PACHYDERMS.]
Cuvierian Pachyderms. _Lign. 255, 256._ _Owen’s Brit. Foss. Mam._ p.
299, &c.; _Wond._ p. 254; _Bd._ i. p. 81; _Petrif._ p. 475.--A large
proportion of the numerous bones and teeth which are found in the
Tertiary gypseous deposits at Montmartre, near Paris, are referable
to the several extinct genera of Pachydermata, which the genius of
Cuvier first made known. The _Palæotheria_ and _Anoplotheria_ must
be familiar to the intelligent reader, for the restored outlines of
several species are appended to almost every work that treats of the
ancient inhabitants of our globe. The details of their anatomical
characters are given at length in _Oss. Foss._ tom. iii., illustrated
with numerous plates.
The Palæotheria (_Brit. Foss. Mam._ p. 316, _et seq._) resembled the
Tapirs in their head and short proboscis, while their molar teeth
approached those of the Rhinoceros, and their feet were divided into
three toes, instead of four, as in the Tapirs. Upwards of eleven
species have been discovered, varying from the size of the Rhinoceros
to that of the Hog. Their remains are extensively diffused in the Upper
Eocene strata in various parts of France; and have been found in the
Isle of Wight.
The Lophiodon (_crested-tooth_), a genus distinguished from the former
by the characters of the teeth, which more nearly resemble those of
the Tapirs, comprehends twelve species, all found in the fresh-water
Tertiary marls of France. A canine tooth of a species of _Lophiodon_
was found in the London Clay, in sinking a well on Sydenham Common,
near the railway.[743]
[743] See Mr. Douglas Allport’s interesting _History of Camberwell_, p.
17, and Owen’s _Brit. Foss. Mam._ p. 306.
The Anoplotheria have two characters not observed in any other animal,
namely feet with two toes (see _Lign. 252_), the metacarpal and
metatarsal bones of which do not unite into a single piece, as is the
case in the ruminants; and teeth placed in a continued series without
any interval between them (_Petrif._ _Lign._ 111); man alone has the
teeth arranged in the same manner. I subjoin figures of molar teeth of
_Palæotherium_ and _Anoplotherium_ (_Lign. 256_).
[Illustration: Lign. 256. Teeth of Palæotherium and Anoplotherium.
_Upper Eocene._ _Isle of Wight and Montmartre._
Fig. 1.--Upper molar tooth (external surface) of Palæotherium
magnum. _Binstead._
2.--Lower molar of Palæotherium magnum.
3.--Grinding surface of first upper molar of Anoplotherium
secundarium. _Binstead._
4.--Inner side view of right upper canine of Anoplotherium
commune.
5.--Upper molar of Anoplotherium commune. _Montmartre._
6.--Lower molar of the same animal.
]
There are also sub-genera, as for example, _Xiphodon_ and _Dichobune_,
characterized by peculiarities of dental and osteological structure;
and _Anthracotherium_ (so named from two species having been found in
a bed of Anthracite or Lignite, near Savone), a genus intermediate
between the Palæotheria and Hogs. The skeletons of these remarkable
animals are imbedded with the remains of carnivora, marsupialia, bats,
birds, crocodiles, tortoises, and fishes.
In England, no remains of the extinct Pachydermata of the Paris
Tertiary strata were discovered until a few years since, and they
are still exceedingly rare. There have been found in the fresh-water
limestone at Binstead, near Ryde, and at Seafield, Isle of Wight, (see
_Geol. I. Wight_, 1854, Prefat. Note,) teeth and portions of the jaws
of two species of Anoplotherium, four of Palæotherium, and one of
_Chæropotamus_, an animal allied to the Hog Tribe (_Geol. Trans._ 2d
ser. vol. vi. pl. iv.; and _Brit. Foss. Mam._ p. 413, &c.).
The _Hyopotamus_ (_Lign. 257_) is a genus of Anthracotherioid
pachyderms, two species of which have been determined by Prof. Owen
(_Quart. Geol. Journ._ vol. iv. p. 103, &c.), from specimens of teeth
found in the upper eocene of the north-west coast of the Isle of Wight,
by the Marchioness of Hastings.
The _Palæotherium_, _Dichobune_, _Dichodon_, _Paloplotherium_, and
others occur in the upper eocene fresh-water deposits of Hordwell Cliff
(see _Charlesworth’s Journal_, No. 1, p. 5, and pl. ii.; _Quart. Geol.
Journ._ vol. iv. p. 17, and pl. iii.; and _Rep. Brit. Assoc._ 1851,
_sect._ p. 67).
Two species of a new genus, intermediate between the Hog and the Hyrax,
named by Professor Owen _Hyracotherium_, have been discovered in the
eocene sands at Kyson, in Suffolk, and in the London Clay of the cliffs
at Studd Hill, about a mile to the west of Herne Bay.[744] The latter
specimen consists of a mutilated skull, about the size of that of a
Hare, with the molar teeth perfect.
[744] Geol. Trans. 2d ser. vol. vi. pl. xxi. p. 203; and _Brit. Foss.
Mam._ p. 419, &c.
The _Paloplotherium_, an allied genus, from Hordwell Cliff, is
described in _Geol. Journ._ vol. iv. p. 103.
The other large fossil Pachyderms, belonging to the two existing genera
of Rhinoceros and Hippopotamus, are found very extensively distributed
in alluvial debris, in the ossiferous breccia of caverns, and in other
pleistocene deposits; and their remains are frequently dug up in the
superficial marls, clays, gravel, and sand of England. As the teeth of
these animals will occasionally be met with by the collector, a brief
explanation of their form and structure may be useful.
[Illustration: Lign. 257. Hyopotamus.
Incisor Teeth: _nat. size_. _Upper Eocene._ _Isle of Wight._]
Fig. 1.--Inner surface of an incisor of _Hyopotamus_.
3.--Lateral view of an upper incisor of _Hyopotamus_.
4.--Outer aspect of the crown of the same tooth.
5.--Inner aspect of ditto.
2.--Lateral view of the upper incisor of recent Hog (_Sus scrofa_).
(These figures are from plate vii. _Quart. Geol. Journ._ vol. iv.; but the
drawings have been accidentally reversed.)
[Sidenote: TEETH OF MAMMALIA.]
Teeth of Mammalia.[745]--The organization of the teeth in the
herbivorous mammalia essentially consists in the adaptation of
the three elements of dental structure to the peculiar conditions
required by the habits and economy of the different species. Thus,
in the Elephant (_Lign. 259, 260_), Horse (_Lign. 263_), &c., the
dentine, cement, and enamel are disposed in vertical plates more
or less inflected, the enamel and cement penetrating the body of
the tooth, and embracing corresponding processes of dentine; an
arrangement by which a grinding surface, composed of three substances
of unequal densities, is produced and maintained in every state of
detrition (_Owen_). But these teeth do not possess the symmetrical and
complicated structure observable in those of many of the reptiles and
fishes we have previously investigated. In the carnivorous mammalia,
the enamel constitutes an external shell or case, investing the body
of dentine and presenting sharp cusps or trenchant ridges, adapted for
the laceration of flesh, as in the Tiger, or modified so as to form
instruments for snapping and crushing bones, as in the teeth of the
Hyæna. In the Mastodon, the crown of the tooth, when first emerged
from the gum, presents a series of strong conical eminences (_Lign.
254_), that become worn down by use, at first into disks (_Ly._ p.
157), which, by further detrition, coalesce. The tooth of the Elephant
(_Lign._ 259 and 260), on the contrary, consists of vertical plates
of dentine, with an immediate investment of enamel, over which there
is an external layer of cement that binds together the entire series
of plates, often amounting to twenty or more; the horizontal surface
produced by the detrition of such a structure, gives rise to the
well-known grinding surface of the molars of the elephant (_Lign.
259, 260_; _Wond._ pp. 143 and 160; _Ly._ p. 159; Owens _Brit. Foss.
Mam._ figs. 88-90, &c.). Detached plates of the teeth of Elephants,
particularly of those which belong to the back part of the posterior
grinder, and have not come into use, are puzzling to the inexperienced
collector of fossil remains; and the first indication I obtained of
the existence of the remains of fossil Elephants in Brighton Cliffs
(_Wond._ p. 150), was from a mass of this kind, dug up in sinking a
well in Dorset Gardens, and sent to me as a "petrified cauliflower."
[745] For the minute structure of the dental organs, the modes of
dentition prevalent in the mammalia, and the homologies of the teeth,
we must refer to Prof. Owen’s often-quoted works, the matchless
_Odontography_, and the lucid and compendious Article on Teeth, in the
_Cyclopædia of Anatomy and Physiology_.
[Illustration: Lign. 258.
Tooth of Mastodon elephantoides: 1/6 _nat. size_.
_Upper Tertiary._ _Ava, Burmah._]
[Illustration: Lign. 259.
Tooth of Elephas primigenius: 1/6 _nat. size_.
_Upper Tertiary._ _Big-bone-lick. N. America._]
[Illustration: Lign. 260. Teeth of Elephants: 1/6 _nat. size_.
The grinding surfaces of the teeth exhibit the arrangement of the bands
of enamel, which have an analogous, but somewhat different distribution
in the teeth of the different species of Elephant.
Fig. 1.--The worn surface of a molar tooth of the African Elephant.
2.--That of the Fossil Elephant or Mammoth (_Elephas primigenius_).
3.--That of the Asiatic Elephant.
]
[Sidenote: HIPPOPOTAMUS.]
[Illustration: Lign. 261. Fossil Molar Teeth of Hippopotamus: 2/3 _nat._
_Pleistocene._
Fig. 1.--Grinding surface of a molar tooth, with the cusps partially
worn away. _Kent’s Cavern, Devonshire._
2.--Perfect molar tooth, seen laterally. _Hertfordshire._
]
I subjoin (_Lign. 261, fig. 1_) a figure of the crown of a fossil
molar tooth of a Hippopotamus, from Kent’s Cavern, Devonshire; in this
specimen the summits of the cusps are worn down by use; and another,
_fig._ 2, representing a perfect molar, with the conical cusps of the
crown entire, found in Hertfordshire by W. D. Saull, Esq. The form
of the worn surfaces of the molars of the Rhinoceros,[746] is shown
in two different stages in the fossil teeth represented _Lign. 262_.
Sir C. Lyell has given figures of the teeth of the Horse, Ox, Deer,
&c. (_Ly._ p. 160); but teeth of the recent species are so readily
obtained, and so much more instructive, that I would recommend the
student to procure teeth of the domestic herbivorous, carnivorous,
and rodent animals, and preserve them in his cabinet as objects for
comparison with the fossil mammalian teeth he may discover (see _Pict.
Atlas_, pl. lxxii.).
[746] See Translation of a Memoir by Giebel on the fossil remains of
Rhinoceros in the _Quart. Journ. Geol. Soc._ vol. viii. part ii. p. 9,
&c.
[Illustration: Lign. 262. Fossil Molar Tooth of Rhinoceros: 2/3 _nat._
_Pleistocene._
Fig. 1.--A molar tooth much worn down by use; with the fangs nearly
perfect. _In gravel; Petteridge Common, Surrey._
2.--Large molar, very much worn by use; the fangs broken off.
_Kent’s Cavern, Devonshire._
]
[Sidenote: HORSE.]
Fossil Horse. _Lign. 263_; and Owen’s _Brit. Foss. Mam._ p. 383, _et
seq._--The bones and teeth of one or more species of this widely
distributed genus are found in the alluvium, in osseous breccia, and
in caverns in numerous localities in Europe, Asia, and America. The
teeth and bones of the horse are often met with in the Elephant-bed
in Brighton cliffs; they are referable to a small species, about
the size of a Shetland pony. The blue alluvial clay or silt of our
existing river-valleys contains abundance of the remains of a horse not
distinguishable from the recent.
[Illustration: Lign. 263. Teeth of Fossil Horse: _nat. size_.
_Pleistocene._ _England._
Fig. 1.--Right lower canine tooth of young Equus plicidens; from
the Cave at Oreston (Owen’s _Foss. Mam._ p. 394).
2.--Upper molar of a fossil Horse; from the _Elephant-bed_ of
Brighton Cliffs.
]
In the Siwalik hills, collocated with the gigantic pachydermata,
ruminants, and carnivora, the remains of two or more species of
Horse have been discovered. One form (_Hippotherium_) is remarkably
distinguished from any previously known by the extreme length and
slenderness of its I legs, in which respect it must have closely
resembled the Antelope; it did not surpass in size the common Deer.
IV. Fossil Edentata. _Petrif._ p. 476.--The remains of extinct colossal
mammalia, related to the existing diminutive Sloths in the essential
characters of their organization, but modified to suit the peculiar
conditions in which they were placed and the enormous increase in bulk
of their colossal frames, are strewn all over the vast area of those
alluvial plains of South America, called the Pampas (_Wond._ p. 164).
The deposits of these regions[747] consist of--1. Beds of clay, sand,
and limestone, containing marine shells and teeth of sharks; these
are the lowermost strata. 2. Indurated marl. 3. Red clayey earth with
calcareous concretions, in which the bones of colossal terrestrial
mammalia are abundant. This vertical section demonstrates, that an
extensive bay of salt-water was gradually encroached upon, and at
length converted into a muddy estuary, by detritus brought down from
the interior of the country, and in which carcases of land-animals
floated and ultimately became engulphed in the silt. It is in these
last deposits, which now form the immediate subsoil of the Pampas, that
the teeth of the _Megatherium_, _Mylodon_, _Glyptodon_, _Mastodon_,
_Horse_, &c. have been found.[748]
[747] See "Buenos Ayres," &c., by Sir Woodbine Parish, 1852, pp.
209-223.
[748] See the charming volume entitled, "Journal of the Voyage of
H. M. S. _Beagle_," by Charles Darwin, Esq; see also Prof. Owen’s
descriptions in the "Zoology of the _Beagle_," and his Report, laid
before the British Association in 1847.
The Megatherium (_Petrif._ p. 478, _Lign._ 112, 113; _Wond._ p. 167;
_Bd._ p. 139, and pl. v.) is the best known to the general reader, from
the graphic exposition of its configuration and habits by Dr. Buckland,
and the splendid remains of its skeleton presented to the Hunterian
Museum by Sir Woodbine Parish; but this animal is only one of several
species of _Edentata_, equally interesting, and almost rivalling it in
magnitude, which the labours of our own naturalists, Sir W. Parish, Mr.
Darwin, and Mr. Pentland, and of Dr. Lund and other foreign savants,
have brought to light. I can only advert to two other genera, namely,
the _Glyptodon_ and _Mylodon_.[749]
[749] An able memoir in the Penny Cyclopædia, Art. Megatheridæ, and
another under the title "Unau," will present the student with an
epitome of all that is at present known of these extinct beings.
[Sidenote: GLYPTODON.]
Glyptodon (_sculptured-tooth_) clavipes. _Lign. 264._--The bony
tesselated carapace, or shield, which was formerly assigned to the
Megatherium (_Bd._ i. p. 159) has been proved,[750] by the discovery
of other specimens, to belong to a gigantic animal, whose bones are
occasionally found associated with those of the Megatherium, and
which is closely allied to the Armadillo. This discovery was made by
my friend, Sir Woodbine Parish, to whose indefatigable exertions the
Hunterian Museum is indebted for its most splendid relics of fossil
Edentata.[751] The bony dermal coat of the Glyptodon (a fine specimen
of which is in the Hunterian Museum) was not disposed in rings as
in the Armadillo, but is made up of polygonal pieces, accurately
articulating with each other, and continuous over the whole of the
upper part of the body and part of the tail; the tail also is enclosed
in a case of this kind, like a sword in its scabbard (_Petrif._ p. 359,
_Lign._ 75).
[750] See _Geol. Trans._ 1835, p. 438, &c.; and Prof. Owen’s elaborate
Memoir on the Glyptodon in _Geol. Trans._ 2d ser. p. 81, pl. x. xiii.
[751] A restored figure of the Glyptodon, together with the skeletons
of the Megathere and the Mylodon, are beautifully illustrated in the
interesting volume on "Buenos Ayres and the Provinces of Rio de la
Plata." 2d Edit. By Sir Woodbine Parish, K. C. H. &c.
The teeth of this animal, which are eight in number on each side of
each jaw, are sculptured laterally, by two wide and deep channels
(_Lign. 264, fig. 1_), which divide the grinding surface of the
tooth into three portions (_Lign. 264, fig. 2_). The hind foot is
very peculiar (see _Lign. 264, fig. 3_), presenting an extreme
modification of the same general plan of structure as that of the
Armadillo. The skeleton of this animal constitutes the type of a
distinct genus (_Glyptodon_), related to the Armadillo (_Dasypus_).
[Illustration: Lign. 264. Glyptodon clavipes.
Tooth and Bones of the Left Foot of a colossal Quadruped allied to the
Armadillo (_reduced size_).
_Pleistocene, near Monte Video._
Fig. 1.--Side view of a tooth, showing the deep lateral channels. The
original four inches long.
2.--Grinding surface of the same.
3.--Outside view of the left hind-foot. Length of the original about
fourteen inches, from the heel to the toe.
(_From the Geol. Trans. 2d. ser. vol. vi. pl. x._)
]
[Sidenote: MYLODON.]
Mylodon.[752]--By this name is designated a gigantic edentate animal,
allied to the Sloth, and formerly described as a species of Megalonyx,
an almost perfect skeleton of which has been obtained from a fluviatile
deposit, a few leagues to the north of the city of Buenos Ayres, and
is now articulated and exhibited in the Museum of the Royal College
of Surgeons of England.[753] The animal appears to have been imbedded
entire, and soon after its death, for the parts of the skeleton were
found but little displaced, and the very few bones that are wanting,
are such as might easily have escaped the search of the collector.
But this magnificent specimen of the extinct fauna of South America
must be seen to be properly appreciated. The skeleton measures eleven
feet from the fore part of the skull to the extremity of the tail,
the latter being three feet in length; the circumference of the trunk
around the tenth pair of ribs is nine feet nine inches; the Megatherium
is eighteen feet in length, and its girth fourteen and a half feet.
These particulars will serve to convey an idea of the relative size of
these gigantic animals. From certain peculiarities in the construction
of the skeleton of the Mylodon, Prof. Owen, perceiving from the teeth
that it was a vegetable feeder, and probably lived on leaves and the
tender buds of trees, and its enormous bulk and weight forbidding
the assumption that it climbed up trees and suspended itself by the
branches, like the diminutive existing Sloths,--assigns to this
creature the task of uprooting and felling trees, and feeding upon the
foliage of the forests it laid prostrate. A remarkable development
of the substance of the bones of the skull is presumed to hare been
a provision against the fatal effects of a fracture of the cranium,
to which the Mylodon, from its supposed uprooting propensities, is
conjectured to have been peculiarly exposed; and the skull of the
specimen in the College bears proofs of having had two fractures, from
both of which the animal recovered. But whoever looks at the skeleton
will perceive that the fore-feet are admirably adapted for seizing
and wrenching oft the branches, and the hinder feet for clasping the
trunk of a large tree; and there is nothing to forbid the supposition,
that the animal could obtain a constant and ready supply of food, by
climbing up the stem to a sufficient height, and wrenching off the
branches. Prof. Owen states, that the Mylodon unites the two great
groups of the _Unguiculata_ (animals with nails and claws), and the
_Ungulata_ (hoofed animals), for it has both hoofs and claws on the
same feet.
[752] Signifying _molar-tooth_,--a name intended to express that the
animal has only teeth adapted for grinding; but this term is equally
applicable to all the other megatheroid animals.
[753] See "Description of the Skeleton of an extinct gigantic Sloth
(_Mylodon robustus_)," &c., by Richard Owen, F.R.S. Hunterian Professor
of the Royal College of Surgeons, 1 vol. 4to. with twenty-four plates,
1842. The lithographs in this work, by Mr. Scharf, are of the highest
excellence: the figure of the entire skeleton of the animal, on a scale
of two inches to a foot, is admirable.
The dental organs consist of four molars on each side the lower, and
five on each side the upper jaw. The teeth are implanted in very deep
sockets, and are of the same size and form throughout, with a conical
pulp-cavity at the base, indicating that their growth continued
during the life of the animal. In structure they resemble those of
the Megatherium and Sloth (_Bradypus_); being composed of a pillar of
coarse dentine, traversed by numerous vascular or medullary canals,
which is invested with a layer of very fine, dense dentine, with minute
calcigerous tubes, and the whole surrounded by a thick coating of
cementum: no enamel enters into their composition. (_Owen._)
V. Fossil Rodents.--Of the mammalia termed _Rodentia_ or Gnawers (see
_Wond._ p. 143), of which the Mouse, Rabbit, and Beaver are examples,
the remains of several genera are found in a fossil state; particularly
in the caverns containing the bones of Carnivora. Dr. Buckland
collected from Kirkdale Cave-bones of a species of Hare or Rabbit,
Mouse and Water-Rat (_Reliq. Diluv._ pl. xi.).
In the eocene gypseous strata of France, two species of Dormouse and
two of Squirrel have been found. From the tertiary sand at Epplesheim,
with the bones of the Dinotherium, those of a species of Hamster or
German Dormouse (_Cricetus_) were obtained.
Fossil teeth of a species of Porcupine (_Hystrix_) occur in the
pliocene deposits of Tuscany.
Of the Beaver (_Castor_), some undoubted remains have been collected in
this country. Those of a species apparently identical with the recent
Beaver of the Danube, have been discovered in the fresh-water deposits
of Essex,[754] Norfolk, Cambridgeshire, and Berks, and in Scotland; and
the remains of the very large extinct species first observed in Russia
(and named, by M. Fischer, _Trogontherium_,) have been found in the
subterranean forest at Bacton, in Suffolk.[755]
[754] See Mr. Brown’s Paper on Copford, _Quart. Geol. Journ._ vol.
viii. p. 188.
[755] See _Hist. Brit. Foss. Mam._ p. 184, &c.; _Quart. Journ. Geol.
Soc._ vol. iv. p. 42; and _Petrif._ p. 357.
[Sidenote: FOSSIL MARSUPIALIA.]
VI. Fossil Marsupialia.[756]--That the remains of an extinct species
of gigantic _Kangaroo_ should be found in the fissures of the rocks
and in the caverns of Australia, a country in which marsupial animals
are the principal existing mammalia, is a fact that will not excite
much surprise; but that beings of this remarkable type of organization
should ever have inhabited the countries situated in the latitude of
the European continent and of Great Britain, would never have been
suspected, but for the researches of the geologist. The fossil remains
of this class discovered in Australia[757] occur in the pleistocene
deposits of Darling Downs, Melbourne, &c. and in fissures and caves
in the limestone of Wellington Valley, imbedded in red ochreous loam,
and are often incrusted by stalactitic concretions. One of the species
exceeds the largest existing Kangaroo, and its bones are associated
with those of the Wombat, and other marsupial animals (_Ly._ p. 155).
[756] Marsupialia; animals that carry their young in a pouch
(_marsupium_), as the Kangaroo.
[757] Rep. Brit. Assoc. 1844, p. 223.
A species of Didelphys (_Opossum_) has been discovered in the gypseous
limestone of Montmartre, and is figured and described by Cuvier (_Oss.
Foss._ vol. iii. pl. lxxi.; see also _Brit. Foss. Mam._ p. 76). It
consists of a considerable part of the skeleton of a small animal,
imbedded in gypsum; the block containing the specimen has been split
asunder, and some of the bones are attached to the surface of one
moiety, and the remainder to the other. From the character of the
jaws and teeth, Cuvier pronounced that the animal was related to the
Opossum, and confidently predicted that the two peculiar bones which
support the pouch in these animals would be found attached to the
fore-part of the pelvis; accordingly he chiselled away the stone, and
disclosed these _marsupial_ bones; thus proving the truth of those
laws of correlation of structure, which he was the first to enunciate
and establish. But as there are true marsupials in which the _ossa
marsupialia_ are merely rudimentary, for example, in the Dog-headed
Opossum, or "Hyæna" of the Tasmanian colonists (_Thylacinus Harrisii_),
in which they are merely two small, oblong, flattened fibro-cartilages,
imbedded in the internal pillars of the abdominal rings, and are only
six lines long and three or four lines broad,--it follows that in a
fossil state the pelvis of a true marsupial animal may be destitute
of those appendages which are commonly supposed to be an essential
character of the marsupial skeleton. Thus the fossil pelvis of the
Thylacinus, had that species been long ago, as it is soon likely to be,
extinct, would not have afforded the certain evidence of its marsupial
character to which Cuvier triumphantly appealed in demonstration of
the Didelphys of the gypsum quarries of Montmartre; yet the Thylacinus
would not therefore have been less essentially a marsupial animal.[758]
[758] See Prof. Owen, _Zoological Society’s Proceedings_, Dec. 1844.
[Sidenote: FOSSIL MAMMALIA.]
In the Eocene sand at Kyson, near Woodbridge, in Suffolk, among
other mammalian remains (_Ly._ p. 203), Mr. Colchester, of Ipswich,
whose researches have been rewarded by many interesting fossils,
found a fragment of the jaw, with one premolar tooth having two
fangs, of a small animal (_Didelphys Colchesteri_, Owen); and which
Mr. Charlesworth (Curator of the Philosophical Institution of York)
ascertained to belong to a marsupial animal allied to the Opossum.[759]
[759] See _Mag. Nat. Hist._ 1839, p. 450; _Rep. Brit. Assoc._ 1842, p.
73; and _Brit. Foss. Mam._ p. 71, _fig._ 22.
But the specimens above described are far surpassed in interest by
those discovered in the Triassic Bone-bed of Würtemberg and in the
Oolite of Stonesfield; the latter consisting of several jaws and teeth
of marsupial animals.
Triassic Mammalian Teeth.--In the thin layer of rolled bones, teeth,
scales, and coprolite, so extensively spread over the top of the Trias
and at the base of the Lias, both in England and in Würtemberg, and
well known to collectors as the "Bone-bed" of Aust Cliff, &c. (_Wond._
p. 529), a few minute _mammalian_ teeth have been discovered by M.
Plieninger at Diegerloch, near Stuttgart, Würtemberg. They appear to
have belonged to one or more small Insectivorous quadrupeds, and have
been described by Plieninger and Jäger. Sir C. Lyell, in the Prefatory
Note to his Manual, 1852, fully treats of these interesting and most
ancient mammalian remains, and gives several exact figures of the teeth.
[Sidenote: STONESFIELD MAMMALIA.]
Fossil Mammalia of Stonesfield.[760] _Lign. 265._ (_Bd._ pl. ii. _Ly._
p. 268. _Wond._ p. 510.)--The best known examples of the fossil remains
of mammalia in the Secondary formations, and, excepting the teeth just
mentioned, of the highest antiquity, according to our present knowledge
of the earth’s physical history, are several mutilated lower jaws with
teeth, of some very small animals, which are supposed to belong to
insectivorous marsupial quadrupeds.[761]
[760] See Owen’s _Brit. Foss. Mam._ pp. 29-70, figs. 15-20; and
_Petrifactions_, p. 401, _et seq._
[761] A small mammalian vertebra from Stonesfield is in Mr. Morris’s
collection, and has been figured by Mr. Bowerbank, _Quat. Geol. Jour._
vol. iv. pl. i. fig. 4, and pl. ii. fig. 6.
[Illustration: Lign. 265. Lower Jaws of Mammalia; _nat._
_Great Oolite._ _Stonesfield._
Fig. 1.--Phascolotherium Bucklandi. The right branch of the lower
jaw, seen from within, with seven grinders, one canine tooth,
and three incisors.
2.--Amphitherium Broderipii. The left branch of the lower jaw
the inner side; the incisor and canine teeth are wanting
The upper figures are enlarged views of three molar teeth.
(_Geol. Trans._ 2d ser. vol. vi. pl. vi.)
]
These most important organic remains have all been found in the
oolitic calcareous flag-stones of Stonesfield: deposits which, as we
have already had occasion to notice, teem with other relics of great
interest. Two specimens of the natural size are represented _Lign.
265_, and will serve for reference to the collector who may visit that
interesting locality.
The existence of undoubted mammalia in the secondary formations was
first made known by Dr. Buckland (in 1823), who, upon the authority of
Cuvier, stated that the two specimens then discovered at Stonesfield
belonged to marsupials allied to the Opossum (_Didelphys_). These
fossils were the left branches of two lower jaws; both were imbedded in
the stone by the external surface, the inner side only being exposed.
One of the specimens has ten molar teeth in a row; the other (the
beautiful fossil, _fig. 1, Lign. 265_, now in the British Museum,)
has seven molars, one canine tooth, and three incisors. Five other
specimens have since been found.[762]
[762] See _Brit. Foss. Mam._ pp. 15-70, for ample details of their
anatomical characters, and physiological relations.
The _Amphitherium_ had thirty-two teeth in the lower jaw, that is,
sixteen on each side; it is presumed to have been insectivorous, and
to have belonged to the _placental_ mammalia. The _Phascolotherium_
had four true molar teeth, and three or four false molars, one canine,
and three incisors in each branch of the lower jaw; and closely
approximates to _marsupial_ genera now restricted to New South Wales
and Van Diemen’s Land. It is, indeed, as Professor Phillips first
remarked, an interesting fact, that the other organic remains of the
British Oolite correspond with the existing forms now confined to
the Australian continent and neighbouring seas; for in those distant
latitudes, the _Cestracionts_, _Trigoniæ_, and _Terebratulæ_ inhabit
the ocean, and the _Cycadeæ_ and _Araucariæ_ flourish on the dry land
(_Wond._ p. 894).
Thus we have evidence of the existence of the Marsupial order during
the Secondary and Tertiary formations, a proof, as Dr. Buckland
observes (_Bd._ p. 73), that this order, instead of being, as was once
supposed, of more recent introduction than other orders of mammalia,
was, in reality, the most ancient condition under which animals of
this class first existed in the earlier geological epochs, and was
coexistent with many other orders throughout Europe in the Eocene
period; while its geographical distribution in the existing fauna is
restricted to North and South America, and to New Holland, and the
adjacent islands.
VII. Fossil Carnivora.--The fossil bones and teeth of numerous species
of _Carnivora_, the order comprising the mammalia which prey on other
animals, of which the Weasel, Bear, Cat, Dog, &c. are examples, abound
in fissures and caverns, in conglomerated rocks, and in drifted sand
and gravel. The remains of the colossal Pachyderms, the Mastodons and
Elephants, lie buried, for the most part, as we have previously shown,
in the superficial alluvial deposits; but the Carnivora, although
occasionally entombed with the Herbivora in superficial gravels and
loams, are principally found imbedded in the floors of extensive
caverns.[763] In many instances, such immense quantities of bones and
teeth of individuals of all ages, and belonging to but one or two
species, occur in certain caves, as to render it probable that these
were for a long period the dens of the extinct species of Bears,
Hyænas, &c. whose bones they enclose.
[763] _Rep. Brit. Assoc._ 1842, sect. p. 62. For an account of the
ossiferous caves of the Brazils, see _Petrif._ p. 483.
Another remarkable geological condition in which fossil bones
of Carnivora occur, is that of an ossiferous conglomerate, or
_bone-breccia_; that is, a conglomerate formed of fragments of
limestone and bones, cemented together into a hard rock by a reddish
calcareous concretion. This breccia is found in almost all the islands
on the shores of the basin of the Mediterranean Sea; as for example,
at Gibraltar, Cette, Nice, Cerigo, Corsica, Palermo, &c. The most
celebrated of the bone-caves are situated in Franconia, and in many
parts of the Hartz. That of Gailenreuth has long been known for its
fossil treasures, which principally consist of the bones and teeth
of two extinct species of Bears. One of these is equal in size to a
large horse, and is termed _Ursus spelæus_ (Bear of the Caverns); and
skeletons have been found of all ages, from the adult to the cub but
a few days old (see _Wond._ pp. 176, 177). There are numerous caverns
in the neighbouring district, some of which are equally rich in the
remains of Carnivora.[764] Similar fossils are also found in the
consolidated gravel and drift in various parts of Germany, and in the
fissures of rocks containing iron-ore, at Kropp, in Carniola.
[764] A highly interesting account of the Ossiferous Caves of the Hartz
and Franconia, by Sir Philip Grey Egerton, Bart, was published in 1834,
_Geol. Proc._ vol. ii. p. 94. See also Captain Montagu’s notice of the
Sophienhöhle further on, at p. 820.
[Sidenote: BONE-CAVERNS.]
Even in Australia, caves with ossiferous breccia are numerous; but the
bones belong to extinct marsupial animals of genera still existing
in the country (see _Rep. Brit. Assoc._ 1844; _Petrif._ p. 133; and
_Wond._ p. 188). In England, several caverns presenting similar
phenomena have been discovered. That of Kirkdale, near Kirby Moorside,
Yorkshire, is well known from the celebrity it acquired by the graphic
illustration of its contents by Dr. Buckland.[765] This cave, or
rather fissure, for its dimensions were too limited to merit the name
of cavern, was situated in oolitic limestone; it was two hundred and
fifty feet long, from two to fourteen high, and six or seven wide. The
floor was occupied by a bed of indurated mud, covered over with a thick
crust of stalagmite; the roof and sides being invested with a similar
calcareous sparry coating, as is commonly the case in all fissures in
limestone rocks.[766] From this cave were obtained numerous bones of
Hyænas, associated with bones, more or less fractured, of Tiger, Bear,
Wolf, Fox, Weasel, Elephant, Rhinoceros, Hippopotamus, Horse, Deer,
Ox, Hare or Rabbit, Mouse, Water-rat, and fragments of skeletons of
Ravens, Pigeons, Larks, and Ducks. Many of the bones exhibited marks
of having been gnawed, and crushed by the teeth of some animals. From
all the facts observed, and which are detailed by Dr. Buckland with
his wonted graphic power, it is inferred that the cave was inhabited
for a considerable period by Hyænas; that many of the remains found
there were of individuals carried in and devoured by those animals, and
that in some instances the hyænas preyed upon each other. The portions
of bone referable to the elephant seem to prove that occasionally the
large mammalia were also obtained for food; but it is probable that
the smaller animals were either drifted in by currents of water, or
fell into the chasm through fissures now closed up by stalactitical
incrustations.
[765] Dr. Buckland’s celebrated work, "Reliquiæ Diluvianæ," contains
an admirable description of these caverns and their contents, with
numerous plates. The student, in consulting this volume, must separate
the _facts_ from the diluvial theory, which, at the period of its
publication (1823), they were supposed by Dr. Buckland and other
eminent geologists to confirm.
[766] For a general description of the cave at Kirkdale, see _Wond._ p.
179; and for details, _Reliq. Diluv._ pp. 1-19. The ossiferous caves at
Kirkdale, Torquay, and Banwell are noticed, _Petrif._ p. 482.
Kent’s Cave, near Torquay, Oreston Cave, near Plymouth, and several
other caves in Devonshire, have yielded great numbers of bones and
teeth of Carnivora and Pachydermata (see _Reliq. Diluv._ p. 67).
Kent’s Hole is the most productive ossiferous cavern in England,
and its vicinity to Torquay renders it of easy access. An extensive
collection of teeth and bones was obtained from this cave by the
late Rev. J. MacEnery, comprising, in addition to the usual extinct
Carnivora, skulls and teeth of Badger (_Meles taxus_), Otter (_Lutra
vulgaris_), Pole-cat (_Putorius vulgaris_), Stoat or Ermine (_P.
erminius_), &c. A selection of the choicest specimens in this
collection is deposited in the British Museum.
In Glamorganshire, two large caverns, called Goat’s Hole, and Paviland
Cave, containing numerous bones of Bear, Hyæna, Wolf, Fox, Rhinoceros,
Elephant, &c., are situated in a lofty cliff of limestone, between
Oxwich Bay and the Worm’s Head, on the property of Earl Talbot, fifteen
miles west of Swansea (_Reliq. Diluv._ p. 82).
[Sidenote: FOSSIL CARNIVORA.]
In the western district of the Mendip Hills, in Somersetshire, there
are several ossiferous fissures and caves. The most interesting are
those of Hutton, on the northern escarpment of Bleadon Hill; and of
Banwell, lying about a mile to the east of Hutton. They contain remains
of two species of bear, one (_Ursus spelæus_) of immense size and
strength; and of Tiger, Hyæna, Wolf, Fox, Deer, Ox, and Elephant.[767]
[767] See a Memoir "On the Caverns and Fissures in the Western District
of the Mendip Hills," by the late Rev. D. Williams. Proc. Royal
Society, June 2, 1831, p. 55.
From the caves at Hutton, the Rev. D. Williams obtained the milk-teeth
and other remains of a calf-elephant, about two years old, and those
of a young tiger, just shedding its milk-teeth; also the grinders of a
young horse, that were casting their coronary surfaces; and remains of
two species of hyæna.
But one instance of the fossil bones of Carnivora has been observed
in the south-east of England. It occurred in a fissure in a quarry of
sandstone at Boughton, near Maidstone; among other bones, the lower
jaw of a Hyæna (see Frontispiece of Vol. I.), with the teeth, was
obtained.[768]
[768] See _Mag. Nat. Hist._ 1836, vol. ix. p. 593; and _Quart. Journ.
Geol. Soc._ vol. vii. p. 383.
In the modern silt of our alluvial districts, the remains of
carnivorous animals, formerly indigenous to this island, are
occasionally met with; and the skeleton of the Brown Bear (a species
which inhabited Scotland eight centuries ago), and of the Wolf,
whose extinction is of a yet later date, have been discovered. The
Woodwardian Museum at Cambridge contains an entire skull of the Brown
Bear (_Ursus arctos_), found in the Manea Fen of Cambridgeshire;[769]
in an ancient fresh-water deposit, near Bacton, in Norfolk, the right
lower jaw of the Bear of the Caverns (_Ursus spelæus_), has been
discovered;[770] and the phalangeal bone of a large Bear has been found
by Mr. J. Brown in the pleistocene deposits at Copford, Essex, with
the remains of Beaver, Elephant, Stag, &c. (_Geol. Journ._ vol. viii.
p. 187.)
[769] A beautiful lignograph of this specimen is given in _Hist. Brit.
Foss. Mam._ p. 77, _fig._ 24.
[770] Hist. Brit. Foss. Mam. p. 89.
Thus the remains of fossil Carnivora discovered in England comprise
several kinds of Bear[771] (including the two species of the caverns
of Germany, _U. priscus_ and _U. spelæus_), and of Tiger, Hyæna, Wolf,
Fox, &c.
[771] _Petrif._ p. 398. In the _Pict. Atlas_, pl. lxxiii., is a good
figure of a large Bear’s tooth. Teeth of Bear, Tiger, Hyæna, and
Arvicola, are figured in _Ly._ p. 161.
Although we cannot dwell on foreign localities of Carnivora, I may
mention that the lacustrine pliocene formation of Œningen occasionally
yields fine remains. A splendid specimen, obtained from that locality
by Sir R. I. Murchison, displays almost the entire skeleton of a
Fox-like animal, the _Galecynus Œningensis_ of Prof. Owen.[772]
[772] See _Geol. Trans._ 2d ser. vol. iii. pl. xxxiii.; and _Quart.
Geol. Journ._ vol. iii. p. 55.
The Seal, which is one of the marine carnivorous mammalia, also occurs
in a fossil state in England. A femur of a species of _Phoca_ has been
found, with the remains of a Monkey and Bat, in a tertiary deposit in
Suffolk. In the tertiary strata of Malta an extinct species of Seal has
also been discovered. In the bone-beds of New Zealand my son frequently
found bones and teeth of Seals, probably of the species now inhabiting
the South Pacific. (_Petrif._ p. 130.)
Of the Insectivora, the fossil remains of several genera occur.
In England, the jaw with teeth of a large species of Mole (named
Palæospalax,[773] _ancient mole_), has been discovered in a lacustrine
deposit at Ostend, near Bacton, on the coast of Norfolk, associated
with bones of Elephant, Deer, Roebuck, and Beaver. This animal must
have been as large as a hedgehog. The only part of the skeleton
hitherto obtained is a portion of the left side of the lower jaw,
containing six molars; its natural affinities have therefore been
inferred from the characters of the crowns of the teeth.
[773] _Hist. Brit. Foss. Mam._ p. 25.
[Sidenote: FOSSIL CHEIROPTERA AND QUADRUMANA.]
The Cheiroptera (_hand-wings_) or Bats, are mammalia which have the
power of flight, from the bones of the phalanges or fingers being
enormously elongated and giving support to a fine membranous expansion;
they are rarely found fossil, although, from their habits of haunting
and hybernating in fissures and caves, their skeletons often occur
mingled in the earth of the floor of caverns, and imbedded in crannies
of rocks, with bones of extinct animals.
The remains of a considerable portion of the skeleton of one species
of Bat was discovered by Cuvier in the gypsum of Montmartre,[774] and
another example in a gypseous deposit, at Köstritz, in Germany, with
remains of extinct species of other mammalia. Two instances of British
fossil Bats are recorded;[775] the one from Kent’s Cavern, collocated
with the extinct Carnivora, and referred to the Horse-shoe Bat
(_Rhinolophus_); the other from Kyson, in Suffolk, found in the same
deposit with the remains of the Monkey, presently to be noticed.
[774] Discours sur les Révolutions de la Surface du Globe, par Baron
G. Cuvier, 4to. 1826, pl. ii. _fig._ 1.
[775] _Rep. Brit. Assoc._ 1842, and _Brit. Foss. Mam._ pp. 11-18.
VIII. Fossil Quadrumana, or Monkeys.--The illustrious Cuvier, when
commenting on the extraordinary fact, that among the innumerable
fossil relics of the mammalia which peopled the continents and islands
of our planet, through the vast periods comprehended in the tertiary
formations, no traces of Man or of his works occur, emphatically
remarked, that it was a phenomenon not less surprising, that no
remains of the quadrumanous races, which rank next to Man in physical
conformation, should have been found in a fossil state; and that the
circumstance was the more remarkable, because the majority of the
mammalia found in the younger and older tertiary strata have their
congeners at the present time in the warmest regions of the globe; in
those intertropical climates where the existing quadrumana are almost
exclusively located.[776]
[776] Discours sur les Révolutions de la Surface du Globe, p. 171.
Fossil Ape of France.--But the remains of this order have at length
been discovered in the most ancient of the tertiary deposits, and
under circumstances which admit of no doubt as to the antiquity of the
fossils or the strata in which they were imbedded; and almost at the
same time in France and in the Sub-Himalayas; and very recently in the
Brazils and in England. The first European specimen was discovered at
Sansan, near Auch, about forty miles west of Toulouse, by M. Lartet,
with remains of the Rhinoceros, Deer, Antelope, Palæotherium, &c. It
consists of the lower jaw, almost complete, with all the teeth, of an
adult animal, of an extinct species, related to the long-limbed and
tailed monkey, called _Semnopithecus_, of which the Negro Monkey is an
example. A fragment of another jaw has been found in the same locality.
Fossil Monkey of the Sub-Himalayas.--In the inexhaustible mine of
fossil bones, discovered by British Officers in India, the upper jaw of
an Ape was found by Messrs. Baker and Durand, and fragments of other
jaws and some bones were subsequently collected by Dr. Falconer and
Captain Cautley. These relics conjointly established the existence of
a gigantic quadrumanous animal in the groves of India at the Eocene
epoch, when the gigantic Tortoise, the lofty Sivatherium, and the
colossal Mastodon tenanted the plains, and Hippopotami frequented
the marshes and rivers. This fossil Ape also is related to the
_Semnopithecus_.
Fossil Monkey of South America.--Dr. Lund, the eminent Danish
naturalist, to whose indefatigable researches, and successful
determination of the colossal Edentata, we have previously alluded, has
discovered the bones of a gigantic Ape, four feet in height, related
to the Capuchin Monkey, in the ossiferous breccia of the caves of
Brazil.
British Fossil Monkeys, _Ly._ p. 202.--The first fossil relic of a
quadrumanous animal from the British strata was obtained in 1839, from
a bed of Eocene sand, at Kyson, a few miles east of Woodbridge, in
Suffolk, by W. Colchester, Esq. The first specimen found consisted of a
small fragment of the right side of the lower jaw, with the last molar
tooth entire in its socket; another relic is the crown of one fang of
the first molar tooth, of the same species. These relics have been
referred to an extinct species of Monkey, related to the _Macacus_,
which has been named _Macacus eocænus_, in allusion to the geological
age of the stratum in which the remains were discovered.[777] In this
Eocene sand have also been discovered the remains of a Bat (p. 813),
and of a Marsupial (_Didelphys_, p. 805), and numerous fish-teeth
(_Lamna_, p. 594); whilst in the clay overlying this sand were found
the vertebra of a Serpent (_Palæophis_, p. 738) and several teeth of
a Pachyderm (_Hyracotherium_, p. 791). Prof. Owen in the _Hist. Brit.
Foss. Mam._ p. xlvi. figures and briefly notices the relics of another
species of _Macacus_, from the newer pliocene, or pleistocene, brick
earth at Grays, Essex.
[777] Owen, British Fossil Mammalia, p. 1, figs. 1, 3.
Fossil Human Bones.--In the Swabian Alps, human teeth and several
perfect human skulls are said to have been found in deposits in which
elephantine remains also occur. This subject was brought before the
meeting of the German Association for the Advancement of Science at
Tubingen, by Fraas and Jäger, and, if correctly reported, naturally
leads to the conclusion that human beings were contemporaneous with
the extinct elephants and some of the other large pachydermata in the
regions referred to.
[Sidenote: ON COLLECTING FOSSIL MAMMALIA.]
On Collecting and Developing the Fossil Remains of Mammalia.--But few
directions for the developing and repairing of the fossil remains
of mammalia will be required in this place, the suggestions already
offered, and particularly those in vol. i. pp. 45-49, embracing full
instructions on this head.[778] On the method recommended in p. 46, for
strengthening the friable bones of the large mammalia, I may observe,
that the _drying-oil_ is prepared by boiling _litharge_ in oil, in the
proportion of one ounce of the litharge to a pint of oil.
[778] Cement.--The following formula was given me by an eminent
collector and developer of fossils:--
Gum mastic, one ounce;
Rectified spirit of wine, sufficient to dissolve it.
Isinglass, one ounce, soaked in water until soft; then dissolve it in
pure rum or brandy until it is in the state of stiff glue: add to this
a quarter of an ounce of gum ammoniacum, well rubbed and mixed.
Put the two solutions together in an earthen vessel, over a gentle
heat; when thoroughly melted and united, put the mixture into smooth,
well-corked bottles.
_Use._--Immerse the bottle in hot water until the cement is
sufficiently liquid for use.
The search for fossils of this class is attended with much less
certainty of success than for other animal remains. In the following
list, page 818, the localities most likely to be productive are
enumerated; but we have no caverns, as in Germany, so rich in remains
of this kind as to ensure the discovery of specimens by the casual
visitor; for the treasures of the most productive cave, that of
Banwell, are prohibited; the proprietor carefully preserving every
fragment. A short residence near some of the best localities and daily
research are required for obtaining interesting specimens. For example,
a residence at Ryde, for a search in the fresh-water tertiary limestone
at Binstead; at Torquay, for Kent’s cavern; or some other town or
village near the other caves in Devonshire; Herne Bay, for the London
Clay at Studd’s Hill, that produced the Hyracotherium; Woodbridge or
Kyson, for the Suffolk mammalia; Walton and Clacton, in Essex, for
remains of Elephants in the pleistocene deposits of that coast.
In searching for bones and teeth in an unexplored cave, the following
suggestions by Dr. Buckland will be found of great value. Select the
lowest parts in the cavern or fissure into which any mud or clay
can have been drifted or accumulated; and then break through the
stalagmitic crust of the floor, and dig down into the silt and pebbles,
&c. below, in which bones and teeth will be found, if the spot contains
any relics of this kind. As a test for distinguishing the ancient
bones found in these caves from those which may have been recently
introduced, the tongue should be applied to them when dry, and they
will adhere in consequence of the loss of their animal gluten, without
the substitution of any mineral substance, such as we commonly find
in the fossil bones of the regular strata. Human bones found in caves
always possess too much animal gluten to adhere to the tongue when
dry.[779]
[779] Dr. Buckland on Fossil Bones of Bears in the Grotto of Osselles,
near Besançon, in France. _Geol. Proc._ vol. i. p. 22.
Along the eastern coast of England, and often off the mouth of the
Thames, the fishermen dredge up teeth, tusks, and bones of Elephants;
and good specimens may sometimes be thus procured. The Ramsgate
fishermen employed in trawling in the North Sea and English channel,
frequently bring up in their gear fragments of fossil bones of
Mammoths, and other mammalia. From the bank of the Goodwin-sands,
large tusks have been procured. On the shore near Herne Bay, very
fine mammalian remains are occasionally obtained. In the Museum at
Canterbury, there was (and I believe is) a good collection of fossil
bones of large Pachydermata procured from the neighbouring coast. It is
a remarkable fact, that immense quantities of the bones of Mammoths,
or fossil Elephants, are strewn over the bed of the German Ocean and
English Channel.[780] The late Mr. Woodward informed me, that the
teeth and tusks of Elephants collected along the Norfolk and Suffolk
coasts, within his own cognizance, must have belonged to upwards of
five hundred individuals.
[780] _Geol. Trans._ 2d ser. vol. vi. p. 161.
BRITISH LOCALITIES OF FOSSIL MAMMALIA.
Bacton, Norfolk. See _Ostend_.
Banwell Cave, fifteen miles from Bristol, and three from Banwell
Station. Bones and teeth of Bears, Hyænas, a Felis larger than the
Lion; but chiefly of Deer and Oxen.
Berry Head, Devonshire; Cave. Carnivora; as Bear, Badger, Tiger,
Pole-cat, Stoat.
Binstead, near Ryde, Isle of Wight. _Upper Eocene._ Fresh-water
limestone. Teeth and bones of Anoplotherium, Palæotherium,
Chæropotamus, Dichobune.
Brighton Cliffs. Between Kemptown and Rottingdean, in the beds above
the Chalk. _Pleistocene._ Teeth and bones of Elephant, Horse, Deer,
Oxen; jaw of a Whale.
Copford, Essex. _Pleistocene._ Elephant, Stag, Ox, Beaver, Bear, &c.
Crayford, Kent. _Pleistocene._ Elephant, Horse, &c.
Easton, a mile and a half north of Southwold. Mastodon tooth, and
Carnivora.
Folkstone, Kent. _Pleistocene._ On the top of the west cliff and in
the valley; bones of Elephant, Hyæna, Hippopotamus, Ox, Horse, Stag,
&c. (_Quart. Geol. Journ._ vol. vii. p. 257.)
Grays, Essex. _Pleistocene._ Elephant, Monkey, &c.
Harwich, Essex. _Pleistocene._ Elephant’s teeth, &c.
Herne Bay. In _London Clay_; Hyracotherium, Chæropotamus. In
_Pleistocene_ deposits; Elephant, Whale.
Hoe, near Plymouth, raised Beach at. _Pleistocene._ Elephant,
Rhinoceros, Bear, Deer, Whale, &c.
Horstead, Norfolk. _Pleistocene._ Mastodon tooth.
Hutton Caves, near Banwell, Somersetshire. Carnivora, Pachydermata,
&c. See p. 783.
Isle of Man. _Pleistocene._ The gigantic Irish Deer (_Cervus
megaceros._)
Kent’s Cave, near Torquay. The most productive of the British
ossiferous caverns (see p. 813). Bear, Badger, Tiger, Wolf, and other
Carnivora; Rhinoceros, Elephant, and other Pachydermata.
Kirkdale, by Kirby Moorside, Yorkshire (see p. 783). I know not if any
accessible part of this celebrated cave remains.
Kyson, near Woodbridge, Suffolk. On the side of the river Deben, about
a mile from Woodbridge, in the parish of Kyson (Kingston). The strata
consist of, 1. Red crag, the uppermost. 2. London clay, about twelve
feet. 3. White and yellow sand. In this lower Eocene bed the relics of
_Monkey_, _Didelphys_, and _Bat_.
Manea Fen, Cambridgeshire. _Pleistocene._ Skull of Bear.
Newbourn, Suffolk. _Pleistocene._ Mastodon tooth. Leopard.
Newbury, Berks. _Pleistocene._ In the peat and shell-marl, Boar, Ox,
Roebuck, Stag, Beaver, Wolf, Ass, &c.
Norwich. _Pleistocene._ Mammoth’s teeth and bones.
Oreston Cave, near Plymouth. Carnivora, Wolf, Bear, Hyæna, &c.
Ostend, near Bacton, on the coast of Norfolk. In a lacustrine deposit
of dark clay and greenish sand, with charred trunks and branches of
trees. A section presents--1. Uppermost: Drift. 2. Black earth, with
shells. 3. Reddish sand. 4. Norwich crag, in patches. 5. Chalk. Nos.
2 and 3 are lacustrine; and in these Pleistocene beds have been found
Gigantic Mole (_Palæospalax_), Elephant, Deer, Roebuck, fossil Beaver
(_Trogontherium_), jaw of Bear (_Ursus spelæus_). See Hist. Brit.
Foss. Mam. p. 85.
Paviland Cave, fifteen miles west of Swansea; between Oxwich Bay and
the Worm’s Head, Glamorganshire. Rhinoceros, Mammoth, Hyæna, Wolf.
Plymouth. Caverns near elevated Beach, at the Hoe. Elephant,
Rhinoceros, Bear, &c.
Postwick, near Norwich. _Pleistocene._ Tooth of Mastodon.
Seafield, Isle of Wight. _Upper Eocene._ Palæotherium.
Southbourn, Sussex. _Pleistocene._ The plain of alluvial mud and clay,
called the "_Wish:_" a section seen on the sea-shore between the
Sea-houses and the foot of the chalk hills. Elephant, Hippopotamus,
Deer, Horse, Ox.
Southwold, Suffolk. _Pleistocene._ Elephant, Rhinoceros, Horse, Deer,
Mastodon: Otter, in Red Crag.
Stonesfield, near Woodstock, Oxfordshire. _Great Oolite._ The only
known locality in England of remains of mammalia of the Secondary
period. See p. 805.
Studd Hill, a mile westward of Herne Bay. _London clay._
_Hyracotherium_.
Swansea (Paviland Cave, near). See Paviland.
Wirksworth, Dream Cave. A perfect skull of Rhinoceros; in Dr.
Buckland’s museum, at Oxford.
Woodbridge, Suffolk. At Kyson, near Woodbridge. _Eocene._ Teeth of
Monkey, &c.
_Note._--For notices of the occurrence of Mammalian Bones at
Betchworth, Brighton, Dover, East Bourn, Folkstone, Maidstone, Marden,
Peasemarsh, the valley of the Wey, Stonesfield Slate, Thames Valley,
&c., see _Quart. Journ. Geol. Soc._ vol. vii. (consult Index). Of
foreign localities, Tibet, Upper Punjab, Siwalik Hills, Vichy, &c., are
also referred to in the same volume.
BONE CAVES IN FRANCONIA.
⁂ Captain Willoughby Montagu having favoured me in 1844
with an account of the state of the principal caves in Franconian
Switzerland, which he had lately visited, the subjoined extract may
be useful to the continental traveller. The cave of _Sophienhöhle_
appears to be highly interesting; the stalactites remaining uninjured,
and the ossiferous floor in the state in which it was discovered;
whilst the much-frequented caverns have been stripped of every relic
by the spoliations of visitors during the last century and a half.
"The northern part of Bavaria, which is denominated 'Franconian
Switzerland,' is situated about the centre of a triangle, formed
between Bamberg on the N.W., Bayreuth N.E., and Nuremberg S.; the best
road from this latter city diverging beyond Erlangen to the north.
"The nearest route from London is through Belgium, from Ostend or
Antwerp, by the line of railroad which (since October, 1843) passes
on from Liege and Verviers, by Aix-la-Chapelle to Cologne. Thence by
steam up the Rhine, by Coblentz to Mayence, and again by railway to
Frankfort. In summer there are steam boats up and down the Maine,
as far as Wurzburg, daily, and higher up, between Schweinfurt and
Bamberg, which latter distance is performed in eight hours going up.
and five down. Or there is a diligence (_eilwagen_) from Frankfort
direct to Nuremberg, from which place (or Bamberg, &c.) a carriage
must be hired to Muggendorf, the principal village of that interesting
district. It lies about half way on the post road between Erlangen and
Bayreuth, and has two tolerable country inns; the people are civil,
and moderate in their charges, at least for the freshest trout and
good wine of Bavaria.
"This charming spot and neighbourhood attracts not only the geologist
and lover of the picturesque, but also the angler, who finds
excellent fishing in the clear, rapidly-winding streams of the
Wiesent, with its tributary waters, all of which are romantically
placed in the suddenly deep dales of this table-land. The Wiesent
flows through Forchheim into the Regnitz, westward, and this into the
Maine, north.
"As to the time necessary to get there, during the summer days it
would only require one to pass through Belgium to Aix, including the
transit of this frontier into Prussia, with slight search of baggage.
Then, in between four and five hours to Cologne, where the steamers
generally wait for the arrival of these trains; and, taking the first
boat up, it is possible to reach Bingen (if not Mayence late) the
same evening. From Frankfort, by diligence, starting at 11 A.M., and
travelling all night, Nuremberg may be reached on the second day; and
the centre of operations, about Muggendorf, on the fifth from quitting
the sea-coast. In returning by the Maine,--from Wurzburg to Mayence
maybe performed in one long day, and then on the Rhine, the descent
being much quicker than the upward course against the streams, the
return homewards may be accomplished in one day less.
"The nearest way to Ostend is by the South-Eastern Railroad to Dover,
and embark for Belgium.
"The newly-discovered cave, called _Sophienhöhle_, lies on the
right bank of a streamlet, which gives its name to a romantic and
rocky valley, _Ahorn-thal_, and flows S.W. toward Gösweinstein,
until it falls into the Wiesent. The situation of the cave is near
Klaustemerhöhle, and opposite to Ludwigshöhle: and it is far easier
of access than Gailenreuth, and may be inspected by ladies with the
greatest facility. An intelligent female showed us through its lofty
and interesting details. This cave is nearly 300 feet wide, and 150
feet in height. The quantity of fossil bones strewed about the floor
was very great, notwithstanding many of the finest specimens had been
removed, and were to be seen in the neighbouring castle of Count
S----; added to this, the long, pendant curtains of stalactite, and
the stupendous size of the cavern, contributed to make it appear
to me far surpassing in interest that near Gailenreuth, called
_Zoolithen-Höhle_, which I had visited the day before. The keys of
this cavern--for this, as well as the other celebrated caves, is
locked up, to guard against depredations--are kept at the large farm
or steward’s house, hard by. The state of the weather prevented our
visiting Forstershöhle (_Forest Cavern_), which lies further N.E.
beyond the little town of Weischenfeld, near Zeubach; but which, we
were informed, was equal in interest to this of Sophienhöhle. The
tourist desirous of visiting this interesting district, will find Mr.
Murray’s Handbook of Southern Germany an excellent guide: I can vouch
for its accuracy."
RETROSPECT.
_"Ce que nous connaissons est peu de chose; ce que nous ignorons
est immense."_
La Place.
We have now arrived at the close of this argument; we have taken a
general survey of the fossilized relics of the various classes of the
animal and vegetable kingdoms, and have explained the methods by which
the inscriptions on these "Medals of Creation" may be deciphered.
But numerous as are the facts that have passed in review before us,
and great as the accession of geological knowledge has been during
the last fifty years, the data hitherto obtained are insufficient to
elucidate many of the obscure pages of the earth’s physical history;
and to future discoveries must be left the full interpretation of many
phenomena as yet obscurely presented to us.
In vain we endeavour to penetrate the veil which shrouds from our
view many of the mighty events that preceded the history of our race,
for,--although the shades of colossal and unknown forms belonging to
the remote ages of a past eternity obey the spell of the true magician
Science,--yet of the innumerable beings which through countless
centuries
"The Earth has gather’d to her breast again,
And yet again, the millions that were born
Of her unnumber’d, unremember’d tribes--"
how few, comparatively, could even the transcendent genius of Cuvier
reveal!
If we endeavour to trace the order of succession, in which the extinct
and existing types of animal and vegetable organization have appeared
upon the face of our globe, as demonstrated by fossil remains, we at
once perceive how imperfectly our knowledge enables us to present
a true picture of the development of organic life as it existed in
the remotest ages. Ascending from the _Granite_--that shroud which
conceals for ever from human ken the earliest scenes of the earth’s
physical drama--the first glimpses we obtain of animated nature are a
few sea-weeds, shells, and Crustacea. But can we doubt for a moment
that that ancient sea had its boundaries and its shores--that then,
as now, there were islands and continents, and hills and valleys, and
streams and rivers, teeming with appropriate inhabitants? The little
Lycopodiaceous seed-vessels in the Ludlow bone-bed afford as certain
indication of dry land, as the olive branch which the dove brought back
to the Ark; one fact of this kind overthrows a host of theories based
upon negative evidence.
Throughout the lower palæozoic rocks organic life presents numerous
modifications; and the remains of small placoid fishes appear in the
uppermost Silurian. In the Devonian we meet with rare reptilian remains
and foot-prints. In the Carboniferous rocks the sauroid Batrachians
have left their relics and their foot-tracks. In the succeeding
period these reptiles predominate; and on the sands of the Triassic
ocean we have the foot-prints of monster reptiles and the tracks of
bipeds--colossal bird-footed creatures--of which no other vestiges
remain, and to which the existing order of creation affords no parallel.
The last bed of the Trias affords the first indication of Mammalian
life.
We now enter upon that marvellous epoch, during which reptilian
organization obtained its fullest development--when the Iguanodon and
Megalosaurus--
"Mighty Pre-Adamites who walked the earth,
Of which ours is the wreck--"
Byron.
were the principal inhabitants of vast islands and continents. But
here, as at an earlier period, we have proof that warm-blooded animals
existed; and the diminutive marsupial insectivorous Mammalia of the
Oolite and the birds of the Wealden attest that the system of animal
creation was complete.
Leaving behind us the Age of Reptiles, we approach that of the colossal
Mammalia, when extensive countries were peopled by the enormous
herbivorous Megatheres, the Mastodons, and gigantic Pachyderms, long
since become extinct. But with these lost forms many existing races
were contemporary; including the Monkey tribes, which, of all animals,
approach nearest to man in their physical organization. Thus, by slow
and almost insensible gradations, we arrive at the present state of
animate and inanimate nature. But even after the existing continents
had attained their present configuration, in the period immediately
antecedent to the human epoch, innumerable tribes of carnivorous
animals swarmed throughout the temperate climates of Europe; the Tiger,
Hyæna, and Bear prowled through the woods and inhabited the caverns;
and the Horse and Elephant, with gigantic Deer and Oxen, tenanted the
plains.
But of Man and of his works not a vestige appears throughout the vast
periods embraced in this review. Yet were any of the existing islands
or continents to be engulphed in the depths of the ocean, and loaded
with marine detritus, and in future ages be elevated above the waters,
covered with consolidated mud and sand, how different would be the
characters of those strata from any which have preceded them! Their
most striking features would be the remains of Man, and the productions
of human art--the domes of his temples, the columns of his palaces,
the arches of his stupendous bridges of iron and stone, the ruins of
his towns and cities, and the durable remains of his earthly tenement
imbedded in the rocks and strata--these would be the "Medals of
Creation" of the _Human Epoch_, and transmit to the remotest periods of
time a faithful record of the present condition of the surface of the
earth, and of its inhabitants.[781]
[781] See Sir H. Davy’s Last Days of a Philosopher.
APPENDIX TO PART III.
PROFESSOR OWEN’S CLASSIFICATION OF THE ANIMAL KINGDOM.
(_From the Hunterian Lectures for 1843._)
Kingdom--ANIMALIA (_animals_).
Sub-kingdom--Vertebrata (_having a spinal column_).
Class--Mammalia (_animals that give suck_).
Aves (_birds_).
Reptilia (_reptiles_).
Pisces (_fishes_).
Sub-kingdom--Articulata (_having external-jointed skeletons_).
Class--Crustacea (_having an external crust, or hard skin_).
Arachnida (_spiders_).
Insecta (_insects_).
Annelata (_composed of rings_).
Cirripedia (_having curled-feet_).
Sub-kingdom--Mollusca (_soft animals_).
Class--Cephalopoda (_feet around the head_).
Gasteropoda (_belly-feet_).
Pteropoda (_wing-like feet_).
Lamellibranchiata (_with lamellated gills_).
Palliobranchiata (_mantle-gilled_).
Tunicata (_enveloped in a cloak_).
Sub-kingdom Radiata (_radiated animals_).
|
/-----------------------------------------\
Nematoneura Acrita
(_with thread-nerves_). (_with indistinct nerves_).
Class--Radiaria (_rayed animals_).
|
/---------------------------------------\
Echinodermata Acalephæ
(_having a spinous skin_). (_with a stinging skin_).
Class--Polypi (_polypes_).
|
/-----------------------------|-------------------\
Ciliobrachiata Anthozoa Nudibrachiata
(_with ciliated arms_). (_flower animals_). (_with naked arms_).
Class--Entozoa (_internal animals_).
|
/-----------------------------------------\
Cœlelmintha Sterelmintha
(_hollow worms_). (_solid worms_).
Class--Infusoria (_infusorial animalcules_).
|
/----------------------------------------\
Rotifera Polygastrica
(_wheel animalcules_). (_with many digestive sacs_).
PART IV.
NOTES OF EXCURSIONS,
IN ILLUSTRATION OF THE
MODE OF INVESTIGATING GEOLOGICAL PHENOMENA,
AND OF COLLECTING
ORGANIC REMAINS.
GEOLOGICAL EXCURSIONS.
------------ "Let the moon
Shine on thee in thy solitary walk;
And let the misty mountain winds be free
To blow against thee; and in after years,
When these wild ecstasies shall be matured
Into a sober pleasure,--when thy mind
Shall be a mansion for all lovely forms,
Thy memory be a dwelling place
For all sweet sounds and harmonies, oh! then
If solitude, or fear, or pain, or grief
Should be thy portion, with what healing thoughts
Of tender joy wilt thou remember me
And these my benedictions!"
Wordsworth.
I now propose to conduct the reader to a few British localities, and
point out the mode of examining geological phenomena in the field,
and of collecting organic remains from the rocks and strata; in other
words, afford a practical illustration of the advantages to be derived
from the knowledge acquired by our previous investigations. But from
want of space, only one or two excursions can be described in detail;
and I must restrict myself in a great measure to extracts from my
note-book, and explanatory remarks and suggestions for the guidance
of the student and collector. The subjects will be arranged in the
following manner:--
1. Instructions for collecting specimens.
2. Excursions illustrative of the geological character and organic
remains of the Tertiary deposits of the London and Hampshire basins;
namely, to the Isle of Sheppey, Bracklesham Bay, &c.
3. Notes for a geological Excursion over the Chalk and Wealden
districts of the South-east of England; from London, by Tilgate Forest,
to Brighton. Also, from Brighton to Rottingdean.
4. Geological notes of various places on the line of the Great Western
Railway, from London to Clifton.
5. Excursion to Matlock and its vicinity; to examine the nature and
position of the mountain limestone and associated strata of that part
of Derbyshire.
6. Geological Notes for an examination of the central group of the
plutonic or igneous rocks of England, and of the Carboniferous and
Slate strata through which they are protruded: in an Excursion to
Charnwood Forest, by Leicester, Mount Sorel, Swithland, Woodhouse, &c.
to Whitwick.
CHAPTER XX.
GENERAL INSTRUCTIONS FOR THE COLLECTION OF SPECIMENS.
"And some rin up hill and down dale, knapping the chucky stones
to pieces wi’ hammers like sae many road-makers run daft--they say
’tis to see how the world was made."
St. Ronan’s Well.
Before we proceed on a geological excursion, it is necessary to be
provided with suitable instruments to detach specimens from the rocks,
and extract fossils from the strata in which we may find them imbedded,
and with materials for packing up our treasures, and noting their
localities on the spot. For this purpose, the following articles will
be found more or less requisite, according to the particular object of
the collector:--
1. A hammer of one of the forms figured in _Lign. 266_. Fig. 3 will be
found most generally useful.
2. A leather or strong camlet bag, and one or two of smaller size; the
former with strings, or with a strap for the shoulder. If travelling in
a carriage, a box or basket may also be provided.
3. Stout and thin paper, and some of a soft kind, for wrapping up
specimens.
4. Chip boxes, and raw cotton, wadding, or tow, for the same purpose.
5. String, sealing-wax, and writing paper gummed on one side, for
labels to affix to specimens on the spot.
6. A strong pair of gloves, and a pair of eye preservers; common
spectacle frames covered with fine black crape will be more agreeable
than glass.
7. A measuring tape, a pocket compass, and drawing materials will be
required, if the observer intend to note the geological characters of
the district.[783]
[783] On the construction of geological maps and sections, see the
Appendix to De la Beche’s _Geological Observer_.
8. A good geological map of the country; if this cannot be procured,
the best geographical map.
9. A strong double-bladed knife; one or more chisels.
10. A pocket set of single lenses of three powers, to examine minute
objects; blank memorandum books.
[Illustration: Lign. 266. Geological and Mineralogical Hammers.
Fig. 1 and 4, 6, are adapted for breaking large stones or masses of
hard rock; the thinner ends are convenient for splitting and trimming
fragments to a moderate size. The head should be from four to five
inches long, one and a half inch wide on the crown, and from two to
three pounds in weight; the length of the handle from eighteen to
twenty inches.
2 and 3.--This is my favourite hammer, and will be found most
generally useful; the short square head for breaking, and the pick
for splitting stones, and extracting fossils of moderate size; weight
of the head two pounds, length seven inches; width of the crown one
and a half inch; handle from twelve to fourteen inches long, and one
inch wide at the lower part, for the convenience of a firm hold. If
the handle be graduated as a foot measure, as in _fig._ 5, it will be
found useful.[782]
[782] Hammers of this kind may be obtained at Messrs. Knight’s,
Foster-lane, London; and at 49, Cockspur-street, Charing Cross: care
should be taken that the heads are of well-tempered steel, and the
handles of tough wood.
5 and 8, 7, are smaller hammers for breaking and chipping stones and
minerals; the heads from three to four inches long, and one and a half
pound in weight; the handle one foot long.
]
Such are the articles that will be required for a geological excursion
intended to comprehend a scientific examination of a district; but
for a mere trip to collect fossil remains, several may be dispensed
with. Some years since, an eminent geologist, Dr. Fitton, drew up
some excellent instructions for collecting specimens, for the use of
the party employed under Captain King to survey the Western coast of
Australia; by permission of the author, they are here subjoined.[784]
[784] For the collection of rock specimens, and for the mode of
observing the phenomena of physical geology, Sir H. De la Beche s
instructive volume, "_How to Observe_," should be consulted.
INSTRUCTIONS FOR COLLECTING GEOLOGICAL SPECIMENS.
"It may be proper to premise, that two of the principal objects
of geological inquiry are, to determine--1st, the nature of the
_materials_ of which the earth is composed: and, 2dly, the relative
_order_ in which these materials are disposed in relation to each
other.
"1. Specimens of rocks ought not, in general, to be taken from loose
pieces, but from large masses in their native place, or which have
recently fallen from their natural situation.
"2. The specimens should consist of the stone unchanged by exposure to
the elements, which sometimes alter the characters to a considerable
depth from the surface. Petrifactions, however, are often best
distinguishable in masses somewhat decomposed; and are thus even
rendered visible in many cases where no trace of any organized body
can be discerned in the recent fracture.
"3. The specimens ought not to be very small;--about three inches
square, and three quarters of an inch in thickness, is a convenient
size.
"4. seldom happens that large masses, even of the same kind of rock,
are uniform throughout any considerable space; so that the general
character is ascertained by geologists, who examine rocks in their
native places, from the average of an extensive surface. A collection
ought, therefore, to embrace specimens of the most characteristic
varieties; and _the most splendid examples are, in general, not the
most instructive_. Where several specimens are taken from the same
place, a series of numbers should be added to the note of their
locality.
"5. One of the most advantageous situations for obtaining specimens
and examining the relations of rocks is in the sections afforded
by cliffs on the sea-shore; especially after recent falls of large
masses, t commonly happens that the beds thus exposed are more or
less inclined; and in this case, if any of them be inaccessible at a
particular point, the decline of the strata will frequently enable
the collector to supply himself with the required specimens, within a
short distance.
"6. To examine the _interior_ of an unknown country, more skill and
practice are required; the rocks being generally concealed by the
soil, accumulations of sand, gravel, &c., and by the vegetation of
the surface. But the strata are commonly disclosed in the sides of
ravines,--in the beds of rivers and mountain-streams; and these,
especially where they cross the direction of the strata, may be found,
by careful examination, to afford instructive sections.
"The mud and gravel in the beds of rivers and in deltas often contain
grains of _gold_, _platina_, and other native metals, rubies,
sapphires, and other precious stones; and a general knowledge of the
rocks of an unexplored country often may be gained from the detritus
at the embouchure of a river.
"7. Among the contents of the strata, the remains of organized
bodies,--shells, corals and other zoophytes,--the bones and teeth of
animals,--wood, and the impressions of vegetable stems, roots, or
leaves, &c. are of the greatest importance; affording generally the
most marked characters of the beds in which they occur. These should,
therefore, be particularly sought after, and their relative abundance
or rarity in different situations noticed. The fossils should, if
possible, be kept united with portions of the rock or matrix in which
they are found; and where they are numerous,--in sand, clay, or any
moist or friable matrix,--it is, in general, better to retain a large
portion of the whole mass, to be examined afterwards, than to attempt
their separation at the time of collecting.
"8. The _loose substances_ which are found above the solid rocks, in
the form of gravel, silt, rolled pebbles, &c., should be carefully
distinguished from the _solid strata_ upon which they rest. And the
more ancient of these water-worn materials, found on the sides or
summits of hills, &c., should be distinguished from the recent mud,
sand, and gravel, brought down by land-floods or by rivers. The bones
and teeth of quadrupeds are not unfrequently found in the more ancient
gravel; and the collection of these remains from distant quarters of
the globe is an object of the greatest interest to geology.
"9. Besides a note of the locality, there ought, if possible,
to accompany every specimen a short notice of its geological
circumstances; as, for example, whether it be found in large shapeless
masses, or in strata? If in strata,--what are the thickness,
inclination to the horizon, and direction with respect to the compass,
of the beds? If these cannot be measured, an estimate should always
be recorded while the objects are in view. Are they uniform in dip
and direction?--curved, or contorted?--continuous, or interrupted by
fissures or veins? Is the whole cliff, or mass of strata in sight, of
uniform composition?--or does it consist of different kinds of stone?
If the strata be different, what is the order in which they are placed
above each other successively?
"10. A _label_, distinctly written, should accompany every specimen,
stating its native place, its relative situation, &c., and these
labels should be attached to the specimens immediately, on the spot
where they were found. This injunction may appear to be superfluous;
but so much valuable information has been lost to geology from the
neglect of it, that every observer of experience will acknowledge its
necessity. It is useful to mark on the labels the day, and even the
hour, when each specimen is collected. This, with a corresponding
note in the memorandum-book, prevents confusion, and will be found to
assist the memory.
"11. A _sketch_ of a coast or cliff, however slight, frequently
conveys more information respecting the disposition and relations of
rocks, than a long memorandum. If numbers, denoting the situation
of the specimens collected, be marked upon such sketches, much time
may be saved at the moment of collecting. But in all such cases,
the memorandum should be looked over soon afterwards, and labels,
distinctly explaining their situation, &c. be attached to the
specimens.
"12. The specimens should be so packed, that the surfaces may be
defended from exposure to air, moisture, and friction: for which
purpose, if strong paper cannot be obtained, dry moss, or straw,
or leaves may be employed. Where paper is used for wrapping the
specimens, they are best secured by fastening the envelope with
sealing-wax.
"Lastly. The collector must not be discouraged, nor be prevented from
collecting, by finding that the place which he may chance to visit in
a remote situation has not a stinking appearance, or the rocks within
his view a very interesting character; _since it frequently, and even
commonly happens, that facts and specimens, in themselves of very
little importance, become valuable by subsequent comparison; so that
scarcely any observation, if recorded with accuracy, will be thrown
away_."
These general instructions will suffice to prepare the reader for an
excursion to some known locality, where his researches will certainly
be rewarded by many interesting organic remains; and he may be so
fortunate as to meet with some rare fossils, and perhaps with one or
two that have not previously been discovered; for there is always a
chance of finding relics hitherto unknown, even in a cliff or quarry
that is daily visited by collectors. And as an old sportsman desirous
of inspiring a novice with a love of field sports, takes him at first
to preserves where game is plentiful, in like manner I would initiate
my reader in the delightful pursuit of collecting _Medals of Creation_,
by conducting him to a spot where these antiquities of nature are
scattered about in great profusion and variety.
CHAPTER XXI.
EXCURSIONS ILLUSTRATIVE OF THE GEOLOGICAL CHARACTERS AND ORGANIC
REMAINS OF THE TERTIARY DEPOSITS OF THE LONDON BASIN.
In leaving London for any part of England, the reader will remember
that the area on which the metropolis is situated, as well as the
surrounding district to a distance varying from a radius of ten to
twenty or thirty miles, consists of the marine Tertiary _eocene_
strata (see p. 24), which have been deposited in, and still occupy,
a depression, or excavation of the Chalk, called the _London Basin_
(_Wond._ p. 229). Around this formation, the Chalk forms a distinct
boundary on the south, west, and north, rising up into chains of hills
or downs; but on the east the range is broken, and the Tertiary basin
lies open to the sea, affording a passage for the Thames and its
tributary streams. From this geological character of the metropolitan
district, it results, that all the lines of railroad proceeding from
London traverse, for the first ten or twenty miles, beds of clay, loam,
and loosely aggregated sand and gravel; hence the numerous slips that
have taken place in the embankments; as for example, at New Cross,
Wandsworth Common, near Hanwell, &c.; and in all these lines it is
obvious, from the nature of the strata and the steepness of many of the
cuttings, that similar catastrophes will again occur.
The next geological feature observable in the lines of all the
London railroads is the Chalk, which is invariably passed either
by steep cuttings, or tunnels, or both; as for example, from near
Croydon to Merstham, by the South-Eastern; from near Basingstoke to
beyond Winchester, by the South-Western; from Maidenhead to beyond
Wallingford, by the Great Western; and from beyond Watford to near
Ivinghoe, by the Birmingham line.
After passing through the Chalk, and over the marls and sandstone
strata of the Cretaceous formation, the Oolitic group (consisting of
Portland stone, Kimmeridge clay, &c.), the Lias, New Red or Triassic,
and Carboniferous deposits successively appear on the lines of
railroad; excepting on those of the South-Eastern, which, upon leaving
the Chalk-formation, traverse the fluviatile beds of the Wealden, as we
shall hereafter more particularly describe.
EXCURSION TO THE ISLE OF SHEPPEY.
Every one knows that Sheppey is a small island about ten miles in
length, lying at the mouth of the Thames, at the distance of between
forty and fifty miles east from London; but every one does not
know that the Isle of Sheppey is an inexhaustible mine of fossil
treasures; and that from its cliffs, and on its shores, may be gathered
innumerable relics of tropical plants, of quadrupeds, birds, serpents,
turtles, fishes, crabs, lobsters, shells, &c. all belonging to species
that now no longer exist.
A visit to the town of Queenborough afforded me, when a boy, the
first opportunity of beholding fossil remains in such a state of
preservation, and in such profusion, as to excite in my mind an
uncontrollable desire to investigate the nature and origin of objects
which I had been taught to believe were either produced spontaneously
in the earth, or were left in their present situations by the waters
of a universal deluge. At a short distance from the inn where we
sojourned, was a vitriol manufactory, and considerable plots of ground
were covered with the pyritous clay, obtained from the neighbourhood.
To my great astonishment, I perceived that masses of this fossil earth
were almost wholly made up of stems, twigs, and fragments of wood, with
innumerable fruits, seed-vessels, and berries, of kinds altogether
unknown to me. These fossils were of a dark colour, some quite black,
very heavy, and permeated with the mineral substance termed sulphuret
of iron, or pyrites. Many were so brittle as to fall to pieces upon
being handled, but others were of a stony hardness, and I quickly
filled a handkerchief with my newly discovered treasures, and hastened
home to examine them at leisure. They consisted of the usual kinds of
fossil fruits so abundant in the island (see _Lign._ 63 and 64, p.
188), with casts of shells, and a few claws of crabs, and teeth of
fishes.
Most of the specimens fell to pieces in the course of three or four
months, but a few were durable, and these still occupy a corner in
my cabinet as precious mementos of my juvenile researches. Many
years afterwards I revisited Sheppey, and made a large collection of
its fossils, which is now in the British Museum. Of late years, the
increasing taste for Palæontology has brought numerous visitors to
the island, which steam navigation has now placed within a few hours’
distance of the metropolis; and the demand for choice fossils has
given rise to several local dealers. The student may, with but little
trouble or expense, visit the island, make himself familiar with its
geological character, and return laden with the fruits of the ancient
spice islands, of whose ruins this mass of clay, in the embouchure of
the Thames, is almost wholly composed. As it is some years since I
last visited this interesting spot, I have obtained, as a Cicerone for
the reader, the most indefatigable and successful investigator of its
fossil Flora, Mr. Bowerbank; and as the courtesy of this gentleman is
equal to his intelligence and scientific attainments, the traveller
will have no reason to regret the absence of the author. A trip from
London to Sheppey and back, affording time to procure a good collection
of fossils, may be easily accomplished in three days.
EXCURSION TO THE ISLE OF SHEPPEY, BY J. S. BOWERBANK, ESQ. F.R.S.[785]
[785] Abridged from the Annals of Philosophy, by permission of the
author.
"The best conveyance is by the Southend and Sheerness steam-packets,
which leave London-bridge on Tuesdays, Thursdays, and Saturdays, at 11
o’clock in the morning, and reach Sheerness about 4 or 5 o’clock in
the afternoon. The town is divided into two parts,--the one contained
within the limits of the garrison being designated the Blue town,
while that beyond the fortifications to the north-east is designated
the Mile-town; and it is to this portion that I should recommend the
visitor to proceed, and take up his quarters either at the Royal
Hotel, or at the Wellington: the latter is an exceedingly snug and
comfortable house, to which I have resorted for many years. After
having established himself in the inn, he should request the attendance
of Mr. Hays (better known perhaps by the name of _Paddy Hays_), from
whom he may purchase, at a reasonable rate, some good fossils, such as
crabs, lobsters, heads and portions of fishes, and numerous species of
fossil fruits. Our traveller will then have accomplished all that can
be done towards the acquisition of fossils until the following morning;
there not being, I believe, any other collector in the town from whom
purchases can be made.
"On the following morning an early breakfast is desirable, as a
considerable extent of ground is to be traversed. It is advisable to
go provided with live or six sheets of soft paper, to wrap fragile
specimens in; and a few cotton or linen bags, of about four or five
inches in diameter, to separate the large from the small fossils; the
whole to be carried in a good-sized blue bag, or haversack; a chisel
and light hammer are the only instruments required. If the geologist
has a desire to view the great section of the London Clay, afforded
by the cliffs on the north shore of Sheppey, and is content with the
comparatively few fossils which he may be able to procure by his own
exertions, he may proceed in the following manner:--Leaving Sheerness
by the new town, he will pass along the sea-wall, towards Minster,
until he reaches Scaps-gate, where the cliffs begin to rise from the
low lands of the western end of Sheppey. A few cottages are scattered
round this point, some of the inhabitants of which work upon the beach,
collecting either cement-stone or _pyrites_, the latter being better
known by the name of _copperas_. To these application should be made
for ‘curiosities,’ and very frequently excellent specimens, and at a
small price, may be thus procured. From this point the route will be
under the cliffs upon the shingle, amidst which, dark patches, ten
or fifteen yards in length, will be observed, composed of nodules of
_pyrites_, intermixed with pyritized fragments of branches of trees, in
great abundance. It is at such spots that the numerous and beautiful
specimens of fossil fruits are found; but, to ensure success, the
collector must be content to go upon his knees, and carefully search
among the fragments. The whole of the beach, from about the parallel
of Minster church to Warden Point, abounds with these patches of
_pyrites_; and I have by this means obtained in the course of a morning
upwards of one hundred fine fruits of various sizes. Care must be taken
in such an investigation of the coast, that it be undertaken during the
falling of the tide, or unpleasant consequences may arise from being
shut in between the banks of mud which are projected into the sea at
many points of the coast.
"If the principal object be the attainment of the greatest quantity of
fossils, a different course should be pursued. The collector should
then, after having made his purchases at Scaps-gate, direct his steps
towards Minster church, passing which, he will proceed on the road
towards Warden. About three-quarters of a mile beyond the church there
is a lane on the left hand, leading towards the Royal Oak, in which
lives a woman named Mummery, and several others, who work upon the
beach, and from whom fossils are frequently to be procured. These
people will direct him to the cottage of a family named Crockford, who
have usually a good assortment of fossils; and to many other parties
who also work upon the beach, and reside between this point and
Hensbrook, to which place he must now direct his steps. At Hensbrook
inquiry should be made for a man named Pead, who has generally a
considerable number of good specimens in his possession. From this
point (Hensbrook) the collector must proceed along the top of the cliff
towards Warden, calling at the various cottages in his way, until he
arrives at Warden Point, at which place he must inquire for Mud-row,
many of the inhabitants of which work upon the beach, and from whom
a considerable addition to the specimens already collected may be
purchased. Beyond this point nothing will be obtained, and the best
way to return to Sheerness, is by the road which runs through the most
level portion of the country; the path along the north cliff undulates
very considerably more than the road.
"The course of proceeding thus sketched applies to the supposition
that the time is limited to three days, but if a longer period can be
spared, I should recommend the tourist not to leave Sheerness without
viewing the dock-yard; and the return to London may be made by the
way of Chatham and Gravesend, affording the gratification of a view of
the dock-yard and lines at Chatham, and of the fine old cathedral and
castle at Rochester; at the same time, enabling him to arrive in London
on the evening of the day that he quits Sheerness."
[Sidenote: HERNE BAY. GRAVESEND.]
If the student’s time will permit, a day or two may be profitably spent
at Herne Bay on his return; and search should be made for fossils under
Swale Cliff and Studd Hill, where numerous fruits and some unique
mammalian remains have been found by William Richardson, Esq. (see p.
791). Should he land at Gravesend, as recommended by Mr. Bowerbank,
he should proceed towards the lime-kilns which lie on the London side
of the pier, on the right bank of the Thames. To the left of the
lime-kilns he will perceive a road leading by some bold chalk cliffs to
the high ground above Gravesend; and on the right hand there is a row
of cottages, or rather huts, inhabited by the labourers that work in
the quarries and kilns. Many of the usual fossils of the Kentish Chalk
may be obtained of the women or children in these huts; and sometimes
_Cidares_, or turban Echinites (p. 314), with spines; and Star-fish
(p. 306). A visit to the chalk-pits at Purfleet, on the opposite side
of the river, is very desirable; many interesting fossils having been
found in that locality. The Kentish Chalk in this district is much
softer than that of Sussex, and the fossils may be easily cleared with
a penknife, or by brushing in water; care should be taken not to wash
them roughly, as they will readily separate from the chalk.
The fossils procured from the Isle of Sheppey, by such an excursion,
will probably consist of portions of stems and branches of trees, and
fragments of wood, perforated by Teredines (see p. 193); specimens of
the fruits of palms, resembling the recent _Nipas_ of the Moluccas (p.
188), and of plants allied to the Cucumber, Bean, Cypress, Laburnum,
&c. (p. 189); claws and fragments of the shields of Crabs (p. 512);
bones of Crocodiles, Serpents, and Turtles; bones and teeth of Sharks
(p. 591); Rays (p. 598), and other fishes; and several species of the
usual shells of the London Clay (p. 383), and a specimen or two of
Nautilus (p. 469).
NOTES FOR AN EXCURSION TO BRACKLESHAM BAT, ON THE WESTERN COAST OF
SUSSEX.
The line of low cliffs extending from Selsea Bill to the mouth of
Chichester Harbour exhibits a section of the Eocene deposits, varying
in height from five or six feet to ten or twelve; it is covered at its
base by a bed of shingle, fifteen or twenty yards wide, that extends
towards the sea. The space between the termination of the shingle and
the limit of low-water-mark is occupied by a bed of dark grey and
greenish sand; and at certain seasons, numberless specimens of the
fossil shells common in the Eocene strata of the London and Paris
basins are thickly spread over this area.
Mr. Webster first directed attention to this locality, in his
celebrated Memoir on the Tertiary Strata of England; and my friend, the
late John Hawkins, Esq. of Bignor Park, followed up the inquiry. In
1821 I made a fine collection of the Bracklesham fossils, and published
a list of them in _Foss. South D._ and _Geol. S. E._ Messrs. Bowerbank,
Saull, Dixon, Coombe, &c. have subsequently made considerable and
important additions to the catalogue; and besides many new species
of shells, the vertebræ and other bones of Turtles, Serpents, and
Crocodiles have been discovered. An excellent notice of this locality,
from the pen of Mr. Bowerbank, appeared in _Mag. Nat. Hist._ (1840);
and I am indebted to the kindness of the author for the following notes
for the guidance of my readers.
"The part of the bay most interesting to the geologist is that
immediately in the neighbourhood of Bracklesham Barn, especially at
about a furlong to the east of that spot, where there is a small
break or chine in the low clay cliff. At this place, and at a few
paces east and west of it, beneath about six or seven feet of clay,
there is a stratum of light green marly sand, abounding in remains
of _Venericardia planicosta_ and other shells, but which is often
entirely hidden by thrown-up shingle, and it is very rarely that more
than a few feet in length of this bed can be seen. It is from this
bed, or from one exceedingly like it, somewhat lower in the series,
that perhaps most of the interesting shells of this district are to
be procured. If we proceed from this little break or chine westward,
for about forty paces parallel to the coast, and then in the direction
of a line at right angles to the cliff, and at the time of low water,
we shall find, near the low-water-mark, the bed we have described as
abounding in fossils exposed by the action of the sea in the most
favourable manner. At this spot _Venericardia planicosta_ is found
literally by thousands, with the valves united, the shells resting
upon their edges, and packed close to each other, exactly in the
manner that we might expect to have found them, supposing them to have
been recent shells with the animals yet inhabiting them. Comparatively
very few are gaping, and their condition and position strikingly
impress upon the mind the idea that when alive they must have
inhabited the spot from which they are now disinterred; especially
as there are numerous small and fragile species of other well-known
London Clay shells, which could not have remained whole had they
been subjected to much attrition amid the larger shells surrounding
them. On the sands in the vicinity of this spot, I found large masses
of _Nummulites lævigatus_ cemented together, and numerous detached
specimens of the same shell.
"At the eastern extremity of this bed, which, at the time of my visit,
was opened for about fifty yards, I found _Sanguinolaria Hollowaysii_,
a rare and fragile, but very beautiful shell, in a fine state of
preservation. At about twenty or thirty yards westward of the western
end of this interesting patch of shells, there are large blocks of
this bed, which, being of a firmer texture than the surrounding parts
of the deposit, have suffered less from the action of the water, and
project about twelve or eighteen inches above the surrounding sand,
and, by presenting an obstruction to the ebbing tide, they usually
induce the formation of a small pool amidst which they stand. At the
south-eastern side of this pool on one occasion I found the stratum,
which is usually covered by the sand, completely exposed. At this
spot there was scarcely a specimen of _Venericardia planicosta_ to be
seen, but instead of this shell, _Turritella conoidea_ and _T. edita_
were imbedded in a dark green marly sand; and among them, together
with _Fusus longævus_ and other well-known London Clay shells, I
found _Venericardia acuticostata_ and _V. mitis_, and a splendid
specimen of _Conus deperditus_, fully equal in size to the one figured
by Deshayes. Westward of this point I did not meet with anything
particularly interesting.
"About midway between Bracklesham Barn and the Thorney coast-guard
station, a series of patches of a deposit of chalk-flints was exposed;
the first of these was nearly at low-water-mark, and the remainder
of them ran, at short distances from each other, in a diagonal
line towards the coast, nearly in the direction of a straight line
drawn from their western extremity to the Thorney station-houses.
Apparently, this stratum of flints has not, at any time, exceeded
eight inches or a foot in thickness; they are, indeed, so thinly
scattered, as rarely to occur piled upon each other: very few of
them have suffered from attrition, and the greater part retain their
original form and whitened surface. They are imbedded in the same
light green marly sand which I before described as occurring at the
bottom of the London Clay in the neighbourhood of the little chine
near Bracklesham Barn. Amongst the flints there are numerous remains
of the roots of trees, in the state of soft bog-wood; which indicate
that this portion of the strata has been very thinly covered by the
superimposed clay.
"Upon one of the bouldered flints, firmly imbedded in the marly sand.
I found the most interesting of the valuable series of fossils which I
had the good fortune to obtain during this excursion, namely, a fine
specimen of _Astræa_[786] attached to the upper and exposed surface of
a flint."
[786] _Astræa_, a species of coral; see p. 262.
As to the accommodation that may be procured near this interesting
geological locality, Mr. Bowerbank informs me that homely fare can be
obtained at the little inn at Bracklesham, but there is only one spare
bed. At Selsea, about six miles distant, there is a much better inn.
NOTES FOR AN EXCURSION TO THE TERTIARY STRATA OF THE ISLE OF WIGHT.
[See Geological Excursions round the Isle of Wight, and along the
adjacent Coasts of Dorsetshire, by the Author. 8vo. 3d edit. With
Prefatory Note by T. Rupert Jones. 1854. Bohn. London.]
Land at Cowes; examine the blocks of fresh-water limestone along
the shore, which abound in shells. Drive to Alum Bay (_Wond._ p.
241), taking Calbourn in your route, where there are quarries of the
fresh-water limestone, with innumerable casts of Paludina, Helix,
Bulimus, &c. Put up at Groves’ Hotel, on the summit of the hill,
commanding a glorious view of Alum Bay, with the Hampshire coast, and
the Isle of Purbeck on the right, and Portland Island looming in the
remote distance; and on the left, the vertical cliffs of Chalk, and
the Needles. The pathway that leads down to the sea-shore traverses a
chasm, separating Headon-hill on the right, from Alum Bay on the left;
in the former, fresh-water shells--in the vertical beds of clay, in the
latter, marine shells--may be obtained in great abundance and variety.
If you land at Ryde, the small quarries at Binstead are worthy of
constant research, for the chance of mammalian remains (see p. 791).
The following extract from the splendid work of Sir Henry Englefield
on the Isle of Wight describes certain geological changes still in
progress on the shore near Ryde, that are well deserving the visitor’s
attention.
"A great and very singular change has taken place within no very
distant period of time on the shores of the Solent, near to Ryde; and
which seems to be still sensibly proceeding. When Fielding, in the
year 1753, was at Ryde, on his voyage to Lisbon, he describes the town
as totally inaccessible by sea except at or near high-water; as the
tide, on its recess, left a vast extent of mud, too soft to bear the
lightest weight. This mud-bank is now entirely covered by a stratum
of fine white sand, smooth and firm enough to bear wheel-carriages,
and which renders the bathing at all times safe and agreeable. This
bed of sand now reaches to Binstead, having covered at least two miles
of the shore within the last half-century; and the inhabitants say
that it is still extending to the westward. On digging through the
sand, the old mud presently appears, the sand stratum being very thin.
To what cause this change is owing it is difficult to guess; but it
is an example of the alternation of deposits from the action of the
sea, in circumstances apparently unchanged, which may afford cause for
reflection to the geologist."[787]
[787] Sir H. Englefield’s Isle of Wight, p. 16.
If the visitor have leisure, he should make a tour of this interesting
island, from Ryde to Shanklin and Ventnor, along the beautiful scenery
of the Under Cliff, formed by the slips of the Lower Green Sand; to
Black Gang Chine, and Fresh-water Bay; visiting Brook-Point (_Wond._ p.
378) to collect fossils from the Wealden strata on the sea-shore.
CHAPTER XXII.
NOTES FOR A GEOLOGICAL EXCURSION, OVER THE CHALK AND WEALDEN FORMATIONS
OF THE SOUTH-EAST OF ENGLAND, FROM LONDON TO BRIGHTON, AND FROM
BRIGHTON TO ROTTINGDEAN.
In travelling from London to Brighton by the railway, the following
geological features of the country may be observed; by a reference to
_Wond._ p. 360, the structure of this remarkable district may be easily
understood.
Leaving the station at London Bridge, the _London Clay_, with its
characteristic fossils, is seen beyond Deptford, by New Cross,
Sydenham, &c.; and approaching Croydon, beds of gravel appear, with
interspersions of olive-green sand. These strata belong to the Eocene
formation, and lie above and upon the Chalk. The valley beyond Croydon
(Smitham Bottom), along the side of which the railroad is carried, is
composed of gravel resting on chalk; beyond the station called _Stoat’s
Nest_, there is a fine section of the chalk, with layers of flint, and
two parallel seams of marl, at the distance of six or eight feet from
each other. These extend, with but little interruption, several miles,
preserving their parallelism, although the strata in many places have
sustained considerable disturbance. The Merstham Tunnel, through the
Surrey chalk hills, is now entered. At Merstham the chalk, chalk-marl,
and firestone are intersected, and the Lower Greensand of Red Hill
appears; and from thence to Horley station, the lower sands and clays
of the Chalk formation are passed over or cut through; affording
sections of sandstone, ironstone, and fuller’s earth.
The strata we have hitherto traversed are of marine origin, and
contain fossil shells, fishes, Crustacea, &c., and remains of other
inhabitants of former oceans. But we now enter upon the series of
river deposits[788] which form the Wealden, and contain the relics of
terrestrial or fresh-water animals and plants.
[788] A limited intercalation of a marine character occurs in the
Hasting Sands of Swanage Bay; this was discovered by Mr. R. A. C.
Austen, and is noticed _Quart. Geol. Journ._ vol. vii. p. lix.
At Horley the weald clay appears, and is succeeded by sand, sandstone,
and shale, to Crawley. Passing through the tunnel of the Wealden
strata, we arrive at Balcombe, where sandstone in laminæ and in thick
beds, having the surface at the lines of junction covered with ripple
marks, is seen on each side the railroad; the dip of the strata is to
the _north-east_. After crossing the deep valley at Balcombe, over
the magnificent viaduct, the line runs along alternations of sand and
clay, dipping _south-west_; we have thus passed over what is termed the
anticlinal axis of the Wealden. Arriving at Hayward’s Heath station,
the tunnel exposes a good section of the Wealden sand, sandstone,
shale, and blue marl or oak-tree clay, to a depth of about thirty-six
yards. The strata are disposed in the same order and thickness as
in the quarries around Cuckfield; namely, fawn-coloured sand and
sandstone, like those of Little Horsted, with beds of calciferous grit
or Tilgate stone; and, beneath, layers of the blue clay. The strata are
very barren in organic remains; several hours’ research only afforded
imperfect vegetable relics, such as comminuted stems and leaves of the
various species of ferns, which occur in Tilgate Forest (see _Wond._ p.
392). Some of the grey laminated sandstones and shales at this place
very closely resemble certain strata of the Coal measures.
Proceeding over the Weald clay with the Sussex marble of St.
John’s Common, the line encounters the Lower Greensand of Sussex,
at Stone-pound gate. Here then we quit the fresh-water strata
of the Wealden, and again enter upon the marine deposits of the
Chalk-formation. At the foot of the northern escarpment of the South
downs, the Chalk is penetrated at the base of Clayton Hill, the
tunnel running through the lower members of the Chalk--the Galt and
Chalk-marl--and emerging at Piecombe through the White Chalk; from
thence to Brighton, the sections and tunnels intersect or perforate the
same cretaceous deposits.
[Sidenote: LONDON AND BRIGHTON RAILWAY.]
In our traverse we shall have seen that the various strata cut through,
are repeated on the north and south of a line drawn from east to west
through the Forest Ridge (see _Wond._ Geol. Map, pl. 1). Thus, the
railroad has to pass through two ranges of chalk hills by tunnels those
of Merstham and Clayton; two principal ridges of Wealden strata--at
Balcombe and Hayward’s Heath; and the Shanklin or Lower Greensand at
Red Hill, in Surrey, and near Hurstpierpoint, in Sussex. There is no
railroad in the kingdom that, in the distance of fifty miles, exhibits
geological phenomena of greater variety or interest.
If the student will refer to _Wond._ p. 362, the stratification above
pointed out will be better comprehended. The sections visible on the
turnpike road from London to Brighton are described, _Wond._ p. 363.
The neighbourhood of Balcombe station will afford some sections of
easy access; and from Hayward s Heath station, Cuckfield is about two
miles distant. The quarries on the hill above that town were formerly
very productive, and the usual Wealden fossils may still be obtained;
namely, casts of several species of fresh-water shells (p. 416), scales
and teeth of fishes (_Lepidotus_, p. 604), bones of reptiles, and
vegetable remains.
Chap. XXII.
GEOLOGICAL STRUCTURE OF BRIGHTON CLIFFS.
"Yes! where the huntsman winds his matin horn,
And the couch’d hare beneath the covert trembles;
Where shepherds tend their flocks, and grows the corn;
Where Fashion on our gay Parade assembles--
Wild Horses, Deer, and Elephants have strayed,
Treading beneath their feet old Ocean’s races."
Horace Smith.
[Illustration: Lign. 267. Brighton Cliffs, near Kemptown,
From the Sea-shore, looking East, or towards Rottingdean.
_a._--The Elephant-bed.
_b._--An ancient Sea-beach, composed of shingle and boulders of granite, porphyry, &c.
_c._--The Chalk which forms the base of the cliff.
]
A stroll from Kemptown along the sea-shore to Rottingdean is replete
with interest, for the strata of which the cliffs are composed clearly
demonstrate that in very remote periods great changes have taken place
in the relative position of the sea and land along the Sussex coast.
Some years since, the bare face of the Cliffs, from the entrance to
the esplanade of the Chain-pier at the Old Steyne, to Kemptown, was
completely exposed, and presented a most interesting section of the
strata. But at the present time, as every one knows, no portion of the
cliffs is visible west of the _groin_ below Kemptown and the sections
in my first work (_Foss. South D._ pl. iv. and v.) are the only
records of the appearances formerly presented, and now concealed by
the sea-wall. Even the cliffs immediately beyond Kemptown are rapidly
diminishing from the action of the waves, which dash with greater
violence against their base in consequence of the means taken to
protect the adjoining terraces from the encroachments of the sea.
The appearance of the Cliffs east of Kemptown is shown in the sketch,
_Lign. 267_. But further along the shore, towards Rottingdean, in
a ravine excavated by the encroachments of the sea, the ancient
chalk-cliff behind the mass of strata seen above is exposed; this is
represented in _Lign. 268_. A description of the appearances at this
point will elucidate the nature of the strata of which these cliffs are
composed.
Upon examining the shore at low-water, masses of chalk, covered with
fuci (_sea-weed_), &c. are seen protruding through the sands; and
towards the base of the cliff a bed of sea-beach is spread upon the
sand; a low wall or terrace of white chalk constitutes the boundary
of this shingle, as seen in _Lign. 267, c_. Thus we perceive, that
the present shore is formed by the continuation of the chalk strata of
the neighbouring Downs, partially covered with sand and beach, which
are the detritus of the flints that have been washed out of previously
existing layers of chalk, and ground down by the action of the waves.
Now, along the eastern part of the coast, towards Rottingdean and
Newhaven, the chalk rises into mural precipices immediately from the
sea-shore; but at this place the cliffs are composed of very different
materials.[789]
[789] _Wond._ p. 113; and _Quart. Journ. Geol. Soc._ vol. vii. pp.
365, 396.
1. In the first place, there is, lying immediately on the terrace of
chalk that forms the boundary-wall of the base of the cliff (_Lign.
267, c_, and _Lign. 268, c c_,), a bed of sand (denoted by the
letter _o, Lign. 268_), of irregular thickness and variable extent:
from this sand marine shells and the jaw of a Whale (see p. 778), have
been obtained.
[Illustration: Lign. 268. Cliffs between Kemptown and Rottingdean: seen
from the West.
_a._--Elephant-bed; calcareous strata, containing teeth and bones of Elephants.
_b._--Ancient Shingle, or sea-beach.
_o._--Red of Sand; containing bones of Whales, and marine shells.
_c, c._--Strata of undisturbed Chalk, dipping towards the Downs.
]
2. Upon the sand is a bed of loose shingle--a regular sea-beach
appearing in no respect different, to the common observer, from that
forming at the foot of the cliffs at the present moment; this bed is
marked _b_, in _Lign._ 267, and 268. Upon examining this shingle, it
is found to contain numerous pebbles and boulders of granite, porphyry,
syenite, and other plutonic rocks (see p. 34), none of which occur in
the present beach. And in this ancient shingle, teeth and bones of
extinct species of Elephant, Horse, and Deer have been discovered.
We have here, then, unquestionable evidence that this beach has been
formed under conditions altogether different from those which now
prevail; for not only is this shingle-bed elevated above the present
sea-level, but its contents are of such a nature as could not have been
thrown up by the sea, in its present relation to the countries that
form its shores.
3. A series of loosely aggregated calcareous deposits, obscurely
stratified, rests upon this bed of shingle, and forms the upper portion
of the cliff, varying in total thickness from fifty to one hundred
and twenty feet. These strata are composed of chalk rubble and loam,
with flints partially water-worn, and boulders and pebbles of tertiary
sandstone; the whole promiscuously intermingled, and deposited in
nearly horizontal layers, from one to three or four feet thick. But
the face of the cliff generally presents a weather-worn and crumbling
aspect, and large masses are constantly falling down, in consequence
of the removal of the ancient shingle, by the effects of the waves
at the spring-tides. From the loose state of aggregation of these
beds, the fallen masses are speedily washed away, but here and there
blocks of great hardness, provincially termed _Coombe-rock_, remain
upon the shore; and, but a few years since, there was a group of high
rocks of this kind near the Chain-pier. This compact conglomerate has
been produced simply by an infiltration of calcareous spar, which has
cemented together the fragments of chalk, flint, &c. In some places,
this infiltration has reached the bed of ancient shingle below, and
large blocks are occasionally found, consisting of pebbles of flint,
granite, &c. held together by veins of calc-spar, in acicular or
needle-like crystals. In these sparry conglomerates, the teeth and
bones of the mammalia previously noticed are sometimes found.[790]
[790] My daughter discovered part of the lower jaw of a Deer, with
teeth, imbedded in this conglomerate, in a mass on the shore near
Rottingdean.
It is in this accumulation of calcareous strata that numerous bones and
teeth of the Mammoth, or fossil Elephant, have been discovered; I have
therefore designated it, the Elephant-bed, to distinguish it from other
loose calcareous deposits.
As seen immediately beyond Kemptown (_Lign. 267_), the cliffs appear to
be entirely composed of the materials above described; but farther on,
the face of the ancient chalk-cliff is exposed (see _Lign. 268_); and
if we extend our walk to Rottingdean, we find in many places the Chalk
alone forming the present cliff; the Elephant-bed and its associated
shingle and sand having been swept away. A like destruction awaits the
remainder of these interesting deposits at no very distant period.[791]
[791] See _Foss. South D._ p. 277, pl. iv.; and _Geol. S. E._ p. 30;
_Wond._ p. 113.
After collecting specimens of the Elephant-bed, both of the friable
varieties, and of the coombe-rock, and a few of the pebbles of granite,
porphyry, &c. from the ancient beach, and also some of the sand beneath
the shingle, to examine microscopically on our return home, let us
sit down on this mass of fallen chalk, and consider the nature of
those changes in the relative position of the land and sea, which the
phenomena before us appear to indicate.
We have seen that these cliffs are composed of the following
deposits:--1. The Elephant-bed (_Lign._ 267 and 268, _a_); a series of
calcareous strata, with bones and teeth of Elephants, Horses, Deer,
and Oxen. 2. An ancient sea-beach (_b_), with pebbles and boulders of
plutonic rocks, and bones of mammalia; and a bed of sand beneath,
in which cetacea and mollusca (apparently of existing species) have
been found. 3. Lastly, the regular Chalk-strata (_Lign. 268, c, c_),
extending far out to sea.
These appearances demonstrate the following sequence of physical
changes, namely--
1stly. The Chalk terrace (_c, c_), on which the ancient shingle-bed
(_b_) rests, was on a level with the sea for a long period; for this
beach must have been formed, like the modern, by the action of the
waves on the then existing chalk cliffs (see _Lign. 268, Chalk_).
But there must have been some cause in operation, by which pebbles and
boulders of granite, porphyry, and other rocks, foreign to our shores,
and bones of Elephants, &c. were thrown up on the strand, and imbedded
in the beach then in the progress of formation. These transported
materials may have been floated to the Sussex coast by icebergs; an
agency by which the delicate bones and teeth might be deposited without
injury, although surrounded by the water-worn detritus (see p. 43).
2dly. The whole line of coast, with the ancient shingle, must have
subsided to such a depth, as to have allowed of the deposition of the
calcareous strata, forming the Elephant-bed. And from the absence of
gravel and beach, and the circumstance of the chalk-rubble, of which
they are largely composed, often presenting angular fragments, it would
appear that this deposition took place in some tranquil bay or inland
sea.
Lastly. The land was elevated to its present level; and at this period
the formation of the existing sea-beach and line of cliffs commenced.
The reader must not conclude, from our remarks being restricted to the
cliffs before us, that the phenomena here contemplated were limited to
this district; on the contrary, if our space would permit, it might be
shown that they are referable to extensive geological changes, which
took place in the period immediately antecedent to the present. In all
the valleys of the South-east and East of England that open into the
sea, traces, more or less extensive and important, of similar deposits
exist. The level plain, called the _Steyne_, at Brighton, is entirely
formed of the Elephant-bed, which extends up the valley to Preston and
Patcham; in the latter place bones and teeth of Elephants have been
found. At Southbourn, the plain at the foot of the Chalk hills, called
"_The Wish_," containing remains of the Elephant, Rhinoceros, and
Hippopotamus, evidently belongs to the same epoch. At Folkstone, Mr. H.
Carr has discovered large blocks of _Coombe-rock_, and Mr. S. J. Mackie
abundance of bones; and at Dover, above the Chalk, similar masses
occur. On the opposite coast of Franco there are also indications
of these deposits. All these phenomena are no doubt connected with
the occurrence of immense quantities of mammalian remains in the
superficial loam, &c. on the eastern coasts of England, and are
referable to the same geological epoch.
Imbedded in the Chalk, which is exposed at low water along the
shore, very large Ammonites may sometimes be found between Kemptown
and Rottingdean; and numerous examples of fossil sponges and other
amorphozoa (p. 219).
The teeth and bones of mammalia are rare in these cliffs, and it is
not probable that any will be obtained in a first visit; but from the
fishermen and boys seen strolling along the shore, specimens may often
be purchased.
CHAPTER XXIII.
GEOLOGICAL NOTES OF VARIOUS PLACES ON THE LINE OF THE GREAT WESTERN
RAILROAD, FROM LONDON TO CLIFTON.
That splendid railway, the Great Western, by which the geologist may
be transported in five or six hours from the Tertiary strata of the
metropolis to the magnificent cliffs of Mountain limestone at Clifton,
exposes in its course several fine sections, and passes within a
moderate distance of some interesting localities of organic remains.
This railroad traverses the _Tertiary_ strata by Ealing, Hanwell, and
Slough, entering the _Chalk_ near Maidenhead, and pursuing rather a
circuitous route to Wallingford, beyond which station it passes over
the _Oolite_, and displays some bold sections of the limestones and
clays of that formation. Near Bath it emerges on the Lias, and crossing
a narrow belt of the _New Red_, passes on to the _Carboniferous_ strata
of the Bristol coal measures.[792] In this route, there are four
places particularly deserving a visit from the geological student, and
collector of organic remains, namely, Farringdon, Swindon, Caine, and
Chippenham.
[792] See Geological Map of England.
Visit to Farringdon.--The railway station is reached in from two to
two and a half hours from London; and an omnibus meets the morning and
evening trains, to convey passengers to the town of Farringdon, which
is about five miles distant.[793] There are two Inns in the town, the
Crown and the Bell, where comfortable accommodation may be obtained.
[793] As there is not a conveyance from Farringdon to meet every train
that stops at the station, the visitor who objects to a long walk
should previously ascertain the time when the omnibus or coach does
arrive, and select a train accordingly.
The town is situated in a valley, between Farringdon Hill, an eminence
seen from a considerable distance in the approach from Oxford, and
Badbury Hill (see _Lign. 269_). A small stream divides the town into
two tithings, called Port and West-port, and flows into the Thames on
the north. The summits of the highest eminences near Farringdon consist
of beds of sand and gravel, resting on Coral Bag and Kimmeridge Clay,
and belonging to the Cretaceous formation, being the littoral deposits
in this area of some sea of that period. The Lower Green or Shanklin
Sand, the Galt, Chalk-marl, and Chalk successively appear in the valley
below Coxwell Furze up to the White Horse Downs.
[Sidenote: EXCURSION TO FARRINGDON.]
I have not observed any organic remains in the strata on the top of
Farringdon and Badbury Hills, but from the pits in the low country
numerous fossil sponges and other _amorphozoa_ (see pp. 227-229)
maybe obtained. One of the most productive "gravel-pits," as they
are here termed, is situated on the road to Little Coxwell, about
three quarters of a mile from Farringdon. It lies on the left of the
road leading to the pretty village of Shrivenham. In this pit, the
strata consist of a coarse aggregate of siliceous particles, with some
lenticular masses in the state of compact conglomerate; the lower
beds are of a whitish grey, the upper of a deep ferruginous colour.
The Windmill public-house, close by, is kept by the owner of the pit
(Panting), and specimens of the "petrified salt-cellars" (see p. 228)
and other sponges may generally be obtained of the inmates; but the
collector, in a few hours, will be able to gather an extensive and
interesting collection; the pick-hammer, _Lign. 266, fig. 2_, will
be found the most convenient instrument. There are two other pits
within a moderate distance of Panting s pit, which are also rich in
fossils. The principal organic remains to be obtained from these
beds are the zoophytes figured p. 227, and _Wond._ p. 637. The reader
should recollect that the beautiful cup-shaped sponge, _Chenendopora
fungiformis_ (_Lign. 71_), is the "petrified salt-cellar" of the
quarry-men. As many specimens as possible of the interesting coral,
_Verticellipora_ (p. 227, _Lign. 70, fig. 4_,) should be procured,
to examine the internal structure at leisure. The cup-shaped sponges
should be collected uncleared, for they are often full of minute
corals, shells, echinital spines, &c. There are also numerous specimens
to be met with of _Terebratulæ_, _Ostreæ_, _Nautili_, and other shells;
also rolled _Belemnites_ from the Oolite, and bones of _Plesiosauri_
and _Ichthyosauri_.
[Illustration: Lign. 269. Section of the strata at Farringdon, Berks;
from Farringdon Hill to the Chalk Downs on the South.
The summits of Farringdon and Bradbury Hills, and Coxwell Furze, are
formed of sands and gravels of the Cretaceous period. The lines on the
Coralline Oolite are not intended to denote the dip of the strata.
Note:--See Memoirs on the Farringdon Sands, by Mr. R. A. C. Austen, in
_Quart. Geol. Journ._ vol. vi. and by Mr. D. Sharpe, _ibid._ vol. x.]
Fossils of the Coralline Oolite.--At a short distance from the town
there is a large quarry of Coral-rag, called Lamb-close-pit, from which
_Cidarites_ (p. 316) and spines, and several species of corals and
shells may be procured. Occasionally Ammonites and Belemnites are met
with in the limestone at this place.
_Stanford pit_, about three miles south-east of Farringdon, is well
worthy of a visit; it consists of the following strata:--
1. Uppermost; _Coral-rag_, three and a half feet.
2. Limestone, containing an abundance of shells, particularly
of Trigoniæ (p. 412), &c. four and a
half feet.
3. Portland sand, of an olive-green colour, three feet.
4. Kimmeridge clay.
Some shells are extremely numerous; principally of the genera
_Trigonia_, _Gervillia_, _Pecten_, _Ostrea_, _Terebratula_, &c.; fine
_Belemnites_ also occur. The oolitic structure is very apparent in the
upper beds of limestone.
Swindon, Wilts.--Fourteen miles beyond the Farringdon station of the
railway, we arrive at that of Swindon. About a mile from this station,
on the rising ground to the south, stands the little, and formerly
retired, town of Swindon. Here, when a schoolboy, my curiosity was
strongly excited by the so-called petrified "_ram’s horns_," and
"_oak_," so abundant in the solid masses of stone in the neighbouring
quarries, and which daily came under my notice in my rambles around
the town. It is indeed a locality most prolific in the Ammonites and
other shells, and in the fossil wood peculiar to the upper division of
the Oolite formation--the Portland beds; the hill on which the town
is built consisting of those strata; the Kimmeridge Clay, on which
they rest, is exposed in the railway cuttings in the valley on the
north. There are two little Inns, the Bell and the Goddard Arms, where
the visitor may meet with accommodation. The quarries, which are in
the immediate vicinity of the town, abound in Ammonites, Trigoniæ,
and other shells: and some layers are entirely composed of the casts
of several species. The Ammonites are principally of two kinds, viz.
_A. biplex_ and _A. triplicatus_, and vary in size from a few inches
to upwards of three feet in diameter; the specimens are casts only,
no vestiges of the shells remaining. At Aylesbury the same species
occur in clay, with the shells entire (see p. 481). A large collection
may be made in a few hours; and from some of the quarry-men the less
common forms may probably be obtained. Casts of the bivalves called
_Gervillia_ and _Perna_ abound in the quarry on the right hand of the
road. I have collected from this place, in addition to those above
mentioned, casts of the genera _Buccinum_, _Cardium_, _Cytherea_
or _Venus_, _Nerita_, _Terebra_, _Pullastra_, _Pecten_; and of the
large species of _Pleurotomaria_ which occurs in the Kimmeridge
clay of Hartwell, with the shell perfect (p. 428); also vertebræ of
_Ichthyosauri_.
A section of the strata from Swindon to the nearest point of the chalk
hills would pass over, in succession,--1. Portland Oolite; 2. Lower
Greensand; 3. Galt; 4. Upper Greensand; 5. Chalk-marl; and, 6. Chalk.
[Sidenote: EXCURSION TO CHIPPENHAM AND CALNE.]
Chippenham and Calne.--In from three and a half to four hours the
traveller from London reaches the town of Chippenham, ninety-three
miles from London, and situated on the Oxford clay; the locality
where Mr. William Bye obtained those interesting specimens of
_Belemnoteuthis_, that contain vestiges of the soft bodies and arms
(see page 459, and _Lign. 145_).
Calne, about six miles from Chippenham, stands on Oolitic limestone;
and the quarries around the town have long been celebrated for the
perfection and abundance of their fossil remains; particularly of
various species of the turban echinites (_Cidarites_, see p. 316), and
their spines. A day or two at each of these towns will be well spent by
the geologist and the collector of organic remains.
Bath and Bristol.--The immediate vicinities of these cities are rich in
interesting localities for the geologist. A visit to the public museums
in Bath and Bristol cannot fail to gratify the student, and will at
once point out to him the places most worthy his examination. That of
Bristol is admirably arranged, and contains, among other treasures,
the specimen of fossil _Squaloraia_ (see p. 596); the remains of the
reptiles of the magnesian conglomerate, the _Thecodontosaurus_ (p.
713); and the celebrated collection of Crinoidea (p. 283) formed by the
late Mr. Miller.
[Sidenote: EXCURSION TO CLIFTON.]
Clifton.--The stupendous rocks of mountain limestone which flank both
sides of the Avon in its course from Clifton to the Severn are too well
known to render a general description necessary, and our limits will
not admit of details. The geological student should first obtain a
_coup d’œil_ of the appearance and position of the strata, by sailing
down to the embouchure of the river in a steam-packet, and afterwards
visit on foot the most interesting localities. On the right bank of
the river, near the "Black Rock," the teeth of several kinds of fishes
of the genera _Psammodus_ (p. 587), _Hybodus_ (p. 591), _Ceratodus_
(p. 587), &c. may be obtained, and shells and corals of the mountain
limestone. Polished specimens of the coralline marbles may be purchased
at the shops.
_Portishead_, a pretty little village on the south-east bank of the
Severn, is well worth a visit; and, by going in the morning steamer
and returning in the evening, several hours may be agreeably spent
along the shore below the hotel; and fossil plants and shells, from the
blocks of millstone grit, and numerous rock specimens may be collected.
A sail to _Chepstow_, and up the Wye as far as Tintern Abbey, returning
on foot, or in a carriage, by Piercefield to Chepstow, is an excursion
replete with the highest interest and enjoyment. The picturesque
beauties of the Wye are dependent, like those of Clifton and Matlock,
on the disruptions which the strata of mountain limestone have
sustained. The magnificent scenery as we pass up the river, and the
interesting associations connected with the ruins of Tintern Abbey,
cannot fail to delight the traveller; but the enchanting scene that
bursts upon the sight from the heights of Piercefield is magnificent
in the extreme, and equal to the grandest views on the Rhine. Looking
down from those elevated pinnacles of rock, which are covered with the
most luxuriant vegetation, and crested with forests of pine, oak, and
beech, we perceive the Wye pursuing its tortuous course at our feet,
and winding along, around promontories of limestone, towards Chepstow;
while immediately beyond, and apparently separated from the opposite
bank of the river only by a precipitous rampart or mountain limestone,
the Severn appears as a vast inland sea, bounded in the remote distance
by the country around Gloucester, and extending on the right to the
Bristol Channel.
Among other interesting geological sites within a few miles of Clifton
and Bristol, may be mentioned--
1. Aust Cliff; a section of the Lias, from which many interesting
fossils have been procured.
2. Banwell Cave; which is particularly deserving of examination (see p.
809).
3. Cheddar Cliffs; which are equally interesting to the geologist
and to the lover of picturesque scenery. They are about twenty miles
from Bristol; and a carriage and pair will be required, if the visitor
intends to return the same day. The best arrangement is to visit the
cavern at Banwell, remain in the neighbouring town the following night,
and make an excursion to Cheddar Cliffs the next day.
There has lately been opened at Cheddar a cavern which surpasses in the
beauty of its stalactites any hitherto discovered in England. The Rev.
W. D. Conybeare states, that it is the only one that at all realizes
any idea we have of the far-famed _Grotto of Antiparos_. It consists of
one grand arch, or porch, and three or four lateral branches and narrow
fissures, about ten or twelve feet broad, and from thirty to forty feet
high, vested and draped with the most fantastic hangings of stalactite.
The floor is a mass of stalagmite, covering a bed of gravel of the
mountain limestone, which fills up about ten feet of the bottom. I am
not aware that any fossil bones have been observed.
When visiting Banwell, inquiry should be made if there be any Cave at
Hutton accessible to the visitor.
The above remarks must be regarded only as suggestions; for it would
require a volume to particularize the geological objects of interest
within a short distance of Bristol. The coal-mines in the neighbourhood
of Bath and Bristol should be visited, and fossil plants collected.
CHAPTER XXIV.
GEOLOGICAL EXCURSION TO MATLOCK.
------ "In famed Attica such lovely dales
Are rarely seen; nor can fair Tempè boast
A charm they know not."
Lord Byron.
The beautiful and romantic Dale of Matlock, although one hundred and
forty-two miles distant, is now brought within nine hours of the
metropolis. Leaving London from the Euston-square station of the
Birmingham Railway, at eleven o’clock (taking the precaution to have a
ticket that will ensure a passage from Rugby by the _Midland_ Counties
Railroad to Derby), we pass over in succession the clays, sands,
and beds of gravel, composing the _Tertiary_ strata of the London
basin; and at Watford, steep cuttings of these deposits are seen on
each side of the station. A long tunnel through the _White Chalk_ of
Hertfordshire is then passed; and at Tring we arrive at the termination
of the Chalk, and obtain a fine view of the north-west escarpment of
the Downs, which is seen extending on the right towards Ivinghoe, and
attaining an elevation of 900 feet. The railway then proceeds over the
Chalk-marl, Galt, and Lower Greensand, to near Leighton, where these
members of the Cretaceous system are succeeded by the _Oolite_ of
Buckinghamshire and Northamptonshire; and the line crosses the Grand
Junction Canal near the emergence of the _Lias_; the Rugby station
being situated in the midst of that formation. We then enter the
Midland Counties line, and pass on to Stoney Stanton, where the Lias
terminates, and the _Triassic_ or _New Red_ strata appear; proceeding
towards Leicester, clays and marls of a dull red colour, denoting the
Triassic deposits, constitute the slopes on each side the railway. As
we approach Leicester, the craggy summits of Charnwood Forest appear in
the distance On the left, with here and there an isolated conical hill,
indicating the protruded masses of granite, porphyry, and syenite,
which belong to the group of plutonic rocks of the central county of
England. The granitic mass of Mount Sorel is seen along the railway
from Sileby to Barrow, Charnwood Forest appearing in the distance.
Leaving Leicester for Derby, the route continues along Triassic strata;
and a good section of the variegated marls, with veins of white fibrous
gypsum, may be observed at _Red Hill_, where a short tunnel perforates
a ridge of the same deposits. The railroad then emerges on the verdant
alluvial plain through which the Trent, its waters increased by the
confluence of the Dove and the Soar, pursues its course towards the
north, and joins the Humber at Alkborough, whence the united streams
flow on, and empty themselves into the German Ocean.
At Derby, where the train arrives at half-past five, half an hour is
allowed for dinner; and we then proceed by the _North Midland_ line, by
Duffield and Helper, through a beautiful valley watered by the Derwent,
which is seen winding its way towards Derby. The high grounds skirting
this valley are composed of the millstone-grit and sandstone of the
Carboniferous system (see p. 31). Ten miles beyond Derby, we arrive
at Amber Gate station, where an omnibus and other conveyances are in
waiting, to convey passengers to Cromford and Matlock.[794]
[794] As it frequently happens that more passengers are brought by
the train, than the omnibus or coach can convey, some activity is
necessary to secure an outside place, which it is most desirable for
the s geological tourist to possess, that he may command a good view of
the splendid scenery, which will be constantly opening on his sight,
through the romantic pass that leads to Matlock.
[Sidenote: EXCURSION TO MATLOCK DALE.]
The road from Amber Gate leads through a succession of picturesque
scenes of surpassing beauty. At Whatstandwell-bridge[795] (see _Lign.
273_), over which the Derwent is crossed, the view is most imposing.
The river is seen rapidly pursuing its course between richly wooded
ravines, fringed with luxuriant foliage to the water’s edge.[796] As we
advance, the bold mountain ridge of _Crich Hill_ appears on the light,
with the village of Holloway at a considerable elevation, and Lea
Mills near the base of the range; while on the left are the hills and
overhanging woods of Alderwasley. Ascending to the Inn at Cromford, the
road turns suddenly to the right, and by an opening cut through a mass
of strata twenty feet thick, called _Scarthing Rock_, conducts to the
southern entrance of Matlock Dale. On passing this chasm, the glorious
features of this enchanting region burst on the view. On the east is a
range of limestone cliffs, richly wooded, with Willersley Castle, the
seat of the Arkwrights, embosomed in trees on a commanding eminence;
and on the west, a rocky precipice, crested with forests, and its sides
partially covered with copses and brushwood; while the river, dashing
through the ravine on the right, completes the magic of the picture--
"So wond’rous wild, the whole might seem.
The scenery of a fairy dream."
Lady of the Lake.
[795] Hotstandwell in the guide-books; _Whatstandwell_ in the Ordnance
Map.
[796] The pedestrian should alight at the little Inn at Whatstandwell,
and walk on to Matlock the following morning.
At the distance of about half a mile, we pass the toll-gate, and a bold
mural precipice of mountain limestone suddenly appears on the eastern
bank of the river; while on the western, a steep slope, clothed with
verdure, rises rapidly to the lofty pine-clad eminence called Masson
Hill, an elevation of upwards of 1,000 feet. The base of this mountain
stretches directly across the dale in front, and apparently presents a
barrier to an egress from the valley on the north; but as we advance,
the road is seen to wind round its foot by a defile along the left
bank of the river; and the magnificent rock called the High Tor rises
in majestic grandeur on the right. The valley now gradually expands,
and, at the distance of about two and a half miles from the entrance
at Scarthing’s rock, terminates in the champaign country beyond
Matlock village.[797] From the precipitous nature of the escarpment of
mountain limestone which forms the eastern boundary of the dale, the
buildings at Matlock Bath are confined to the left or western side of
the Derwent, and are scattered here and there among the trees, on the
projecting plots and terraces formed by the fallen cliffs of sandstone,
which, during the lapse of ages, have become partially disintegrated
and are more or less concealed by vegetable soil; the projecting rocks
are covered with lichens, mosses, and ferns.
[797] The proper name of the hamlet in the valley, generally called
Matlock, is _Matlock Bath_.
The hotels, of which there are several, are all delightfully situated;
but the _Temple Hotel_, which stands on a terrace on the side of Masson
Hill, about a hundred feet above the river, has the preference in my
estimation; its elevated situation, its seclusion from the noise and
bustle of the village, and its bowers and hedge-rows of sweet-briar and
roses, imparting a character of sylvan beauty to the spot, peculiarly
grateful to the traveller who wishes to enjoy a quiet sojourn at
Matlock Dale. The local guide-books afford the necessary information
to direct the visitor to the celebrated picturesque spots of this
beautiful region; our immediate object is to point out the most
important geological phenomena.[798]
[798] The book entitled "The Gem of the Peak," by W. Adams, price Is.,
and the "_Brief Remarks on the Geology and Botany of Derbyshire_," by
the same author, price 1_s._, will be found to contain much valuable
information. The "_Derbyshire Tourist’s Guide_," with plates, 8vo., by
E. Rhodes, price 6_s._, is a delightful hand-book.
[Sidenote: LONDON TO MATLOCK.]
Geological Position of Matlock Dale.--That the reader may clearly
comprehend the geological character of the romantic district in which
he is now situated, we will briefly enumerate the several formations
over which we passed, in our rapid transit from London; by the aid
of the geological map, the following description will be easily
comprehended.
Our route from the metropolis commenced from the centre of the
_Tertiary_ strata, upon which London is situated, and which fills
up an extensive depression or basin in the Chalk; we then passed
over, or rather (by the tunnel) through the north-west boundary of
the _Chalk_ basin, and successively came upon the _Portland_ stone
and other beds of the _Oolite_, and the _Lias_; the strata of these
formations successively rising from beneath each other as we proceeded.
In Leicestershire, the beds of the _New Red_ or _Triassic_ formation
emerged from under the Lias; and at the Trent Junction the nature of
the deposits was concealed by the alluvial plains of the river. Beyond
Derby, we entered upon strata of the _Carboniferous_ system, the
_Millstone grits_ and _sandstones_, and finally reached the Mountain
limestone and its associated _Magnesian limestones_, which compose the
mountainous district of Derbyshire. The following diagram will serve to
illustrate this description.
[Illustration]
The immediate vicinity of Matlock is, therefore, a region of
Carboniferous limestone and millstone strata, which, as we have
previously explained (see p. 31), are of marine origin; and those beds
that contain organic remains abound in extinct species of shells and
crinoidea. These rocks are also the grand depository of the ores of
lead (see _Wond._ p. 681), calamine, &c., and contain a variety of
minerals of great beauty and interest. This district has also been the
theatre, in very remote periods, of great physical changes, and the
strata have been upheaved and displaced by volcanic action, the solid
rocks rent asunder, and beds of mineral substances, rendered fluid
by intense heat, have been injected between the layers, and into the
fissures of the sedimentary strata; to these revolutions, the present
bold and picturesque features of the country are attributable. Here
then are phenomena replete with the highest interest; the very beds
of lava may still be seen--the rents and fissures caused by their
explosive action, and now lined with rich metallic ores and spars, may
be examined--and the thermal waters, rising in perpetual fountains from
an incalculable depth, testify that the internal fires, the sources of
these catastrophes, though latent, are not extinguished.
[Sidenote: MATLOCK INCRUSTING SPRINGS.]
A Walk to the Incrusting Springs.--The so-called "petrifying springs
and wells" of Derbyshire are celebrated throughout England for the
incrusted birds’ nests, baskets, &c. which are very generally purchased
by visitors, as mementos of a trip into this county. The nature of this
deposition of calcareous matter has already been explained (see p.
39; and _Wond._ p. 75); and, although the objects above mentioned are
scarcely worthy of notice, the natural operations by which the tufa and
travertine are produced, are extremely interesting.[799]
[799] If the proprietors of these springs could be induced to follow
the example of the Italians at San Filippo (see _Wond._ p. 75), or
of the French, in Auvergne, or the Germans at Carlsbad, elegant
bas-reliefs and other beautiful objects might be obtained, for the
incrusting power of the Matlock waters is very considerable.
Our first stroll shall therefore be to the beds of tufa which have been
formed in remote ages by this operation and which now constitute the
terrace on which the Old Bath and two other hotels, and the elegant
modern Church are situated. Proceeding from our Inn, the tufaceous rock
may be seen protruding in masses on the right hand, in front of the
beautiful parterres of the hotels; and upon crossing the road, where
a narrow path leads down to the bed of the river, and nearly opposite
to the new church, the lower beds of tufa are exposed in a quarry,
from which large blocks of the coarse, porous stone are extracted for
grotto and rock-work. From this spot I collected very fine impressions
of the foliage of the oak, elm, and hazel, leaves of adder’s tongue
(_scolopendrium_), &c. and large portions of moss, beautifully
incrusted.[800]
[800] I could not obtain any specimens of this kind from the quarry-men
nor from the shops or museums, as they are termed; such objects not
being deemed "curiosities" by the good folks of Matlock; and the
workmen forbade me to search for more in the quarry!
The origin of this deposit of tufa, which covers so huge an area along
the western flank of the mountain range of Masson Hill, is attributable
to the thermal springs having, at some very remote period, issued from
a much higher source than at present, and flowing down the side of the
hill into the river at its foot, the water, as it cooled, deposited
the lime with which it was charged on the stems, branches, leaves, and
other extraneous bodies. At this time the springs escape from crevices
in the rocks at an elevation of about one hundred feet above the bed
of the river; the waters, at their source, have a temperature of from
66° to 68°, and contain free carbonic acid and minute quantities of
muriates and sulphates of magnesia, lime, and soda. Their origin is
now concealed, and the water conducted by pipes to the various baths
and fountains; but wherever a rill escapes, and flows down the hill,
the moss, &c. is quickly incrusted. I was informed, that in about eight
mouths a basket of eggs would be entirely enveloped in a thick mass
of tufa. The uniform high temperature of these waters shows that they
emanate from a very deep source; and it is probable that they originate
from steam, which is cooled and condensed as it approaches the surface
of the earth. The miners assured me, that the springs burst out from
beneath the volcanic rock, here termed _toadstone_, and that the water,
when it first issues, is of a higher temperature than the Matlock Bath
water; but its heat is reduced by the cool land-springs with which it
becomes intermingled.
Most waters that flow through limestone districts deposit travertine
more or less abundantly; and I observed several streams in my rambles
in the neighbourhood of Matlock which appeared to possess this property
in as great a degree as the thermal springs. There is a lovely
waterfall, which issues from the side of a mountain that flanks the
road leading by Via Gellia to Middleton Moor, at an elevation of two
hundred feet, and flows into the adjacent valley, bounding and dancing
from one mossy knoll to another, and appearing from the opposite hill
like a stream of molten silver, undulating through a carpet of emerald
green. The waters of this cascade have formed a thick bed of travertine
along the side of the hill; and the stone is of so firm a texture, that
the walls of a cottage hard by are constructed of it.
I gathered from the banks of this waterfall, bundles of moss and groups
of small shells incrusted with a beautiful white tufa; and impressions
of leaves, twigs, &c. were observable in the blocks of travertine
recently quarried.
In contemplating the effects produced by these limpid streams, by which
perishable leaves and fragile shells are preserved for ages in solid
masses of rock, we are reminded of the forcible and eloquent remarks
of Sir Humphry Davy, when observing similar phenomena in the volcanic
regions of Italy. "How marvellous are those laws, by which even the
humblest types of organic existence are preserved though born amidst
the sources of their destruction; and by which a species of immortality
is given to generations, floating, as it were, like evanescent bubbles
on a stream raised from the deepest caverns of the earth, and instantly
losing what may be called its spirit in the atmosphere!"[801]
[801] "Consolations in Travel; or, the Last Days of a Philosopher;" by
Sir Humphry Davy. See also _Wond._ p. 77.
[Sidenote: CAVERN OF THE HIGH TOR.]
Visit to the Cavern of the High Tor.--After the visitor has taken
a general view of the romantic scenery around him, a visit to the
cavern at the foot of the High Tor will enable him to comprehend the
nature of those physical changes which have imparted to this district
its picturesque character. Descending into the valley and passing
northwards, through the only street in Matlock Bath, along the banks of
the Derwent, which are beautifully overshadowed by copses and forest
trees, the bold cliff of mountain limestone, called the High Tor, the
most imposing feature in the dale, suddenly appears on the right bank
of the river. This rock rises to the height of four hundred feet; the
upper half forming a bare and nearly perpendicular wall of limestone;
the lower portion being concealed by brushwood and luxuriant foliage to
the river s edge. At this spot, a rude wooden hand-rail is stretched
across the Derwent, which is here of considerable breadth, and dashes
along over fallen masses of rock in its course towards the south. The
High Tor (_Lign. 270_) consists of a capping of Drift and of Millstone
grit (2); of a series of beds of limestone with encrinites and shells,
slightly inclined southward (1); of a layer of volcanic matter, termed
in Derbyshire _toadstone_, from its mottled yellow and greenish
appearance (3); and of a bed of _Trap_, or _toadstone_ (_b_), at the
base, and near the floor at the entrance of the fissure or excavation
in the limestone forming the cavern (_a_); which trap rock also appears
on the opposite bank of the river (_c_), beneath the highly inclined
and dislocated masses of limestone, forming part of the base of Masson
Hill. The upper bed of _toadstone_ (3) cannot be seen, for the face of
the cliff (although represented bare for the sake of perspicuity in
the plan, _Lign. 270_) is entirely concealed, half-way up, by dense
foliage; but an intelligent miner assured me that such was the fact,
and that, in sinking a shaft in the opposite hill, _toadstone_ was
found in a corresponding situation. Upon entering the cavern, which is
not of considerable extent, the first phenomenon to be observed is the
bed of _toadstone_, which protrudes near the floor, beneath a stratum
of limestone. The limestone in contact with the trap is in some places
changed to a light green colour, and has a slaty texture, from the
effects of intense heat under great pressure; it is often permeated
with veins of pyrites, and white calcareous spar. The inner recesses
of the cavern are literally covered, both on the floor and sides,
with very large rhomboidal crystals of carbonite of lime, of the form
commonly called _dog-tooth spar_; the cave surpasses, in this respect,
every other in Derbyshire.
[Illustration: _G. A. M. delt._ _J. Whimper, lignt._
Lign. 270. Section across the Valley of the Derwent, at the High Tor,
Matlock.
1.--The High Tor, composed of strata of Mountain Limestone.
2.--Capping of Millstone Grit and Drift.
3.--Supposed position of an intrusion of Trap.
4.--Cliff of limestone on the opposite side of the valley.
_a._--Entrance to the High Tor Cavern.
_b._--Trap seen at the bottom of tile Cave.
_c._--Trap beneath the limestone on the opposite bank of the Derwent.
]
Within a few hundred yards of the cavern, a gallery has been driven
into the cliff, and a vein of lead (_galena_) discovered, and worked
with some success. Tine masses of blue fluor (provincially termed
_blue John_) and double refracting calcareous spar were also obtained.
On the opposite bank of the Derwent, beneath the limestone, and
extending along the road-side for two or three hundred yards, a bed of
_toadstone_, evidently the continuation of that at the base of the High
Tor, is distinctly exposed.
Proceeding northwards, the line of mural precipices, of which the
High Tor is the most elevated point, gradually descends; but there
is a bold and bare rock, called the Church Tor, from the church of
the village of Matlock being situated near its summit, that requires
particular remark; for on the face of this cliff the strata present a
series of curves, or rather arches, nowhere broken, but having such
an appearance as would result from an expansive force from beneath
uplifting a group of horizontal strata, while yet in a soft or plastic
state. The upper beds of limestone at the Church Tor abound in marine
shells (_Spirifer_, see p. 390, particularly the large species, _S.
giganteus_). Such are the appearances presented by the strata in this
locality, on the right bank of the Derwent. On the opposite side of
the valley are beds of limestone, many of them varying in mineral
constitution from those we have examined, being of a light yellowish
dun or cream colour (hence called _Dun-stone_), and containing
magnesia; in these strata traces of fossil plants are occasionally
found. These magnesian limestones are of a granular texture and
extremely hard; they are said to be very rich in lead and calamine,
and have been extensively worked. The prevailing rocks on this (the
western) side of the valley belong to this group.
[Sidenote: FORMATIONS OF DERBYSHIRE.]
Geological Formations of Derbyshire.--Before we proceed on our walk,
let us sit down awhile on this mossy bank, beneath the magnificent
knoll of trees that here overshadows the river, and, by a reference to
the geological table (p. 31) and the geological map, obtain a clear
idea of the nature and succession of the strata around us; in other
words, the order of superposition of the deposits of Derbyshire.
1. _Lowermost._ A bed of compact Basalt or Trap (in Derbyshire
called _Toadstone_), of uncertain thickness and extent. This rock
consists of mineral matter that has undergone complete fusion, and
been erupted from the profound depths of some internal source of
intense heat (see _Wond._ pp. 684, 848). The upheaving force thus
put in action having been unequally exerted in different places, the
superincumbent beds of limestone have been protruded in dome-shaped
masses through the upper strata; and are now seen bent and
curved, forming what is termed arched stratification.[802]
[802] My excellent friend, the late Robert Bakewell, Esq., was the
first geologist who correctly explained the phenomena here described.
See his Introduction to Geology, 5th edit. p. 147.
_Vesicular_ or _amygdaloidal_ Toadstone. This partakes more of the
character of scoriæ, being full of little cells or cavities formed by air
bubbles; when these cavities are filled with other mineral matter, as
is often the case, the rock is termed amygdaloidal. This bed of Trap
was formerly considered to be distinct from the lowermost; but it is
now supposed, and with much probability, that all the masses of
igneous rock that pierce, or are intercalated with, the sedimentary
strata, have sprung from one common source, and are but lateral
protrusions from some grand mass of erupted materials.[803]
[803] See an analogous example, _Wond._ p. 857.
2. Limestones with intervening layers of clay, and Magnesian
limestones, or Dunstones.
3. Alternation of Limestone and Shale. Many of these limestones
abound in organic remains; and it is in this group that the
ornamental marbles of Derbyshire are comprised. The upper beds
are generally of a slaty texture, and contain layers and nodules of
chert, which often afford exquisite siliceous casts of the stems of
_Crinoidea_ (pulley-stones, see p. 284; and _Wond._ p. 650), and shells;
white chert or porcelain-stone, and black jasper or flinty slate also
occur in these beds.
4. Millstone Grit and Shale, and coarse sandstones; these form
the subsoil of the principal heights of the mountain ranges, their
sterile soil supporting only a covering of ling and heath.
5. Coal Measures; consisting of beds of Coal, with intervening
layers of shale, clay, and ironstone (see p. 80).
6. Permian and Triassic strata (see pp. 29, 30).
The mineral substances found in the above strata in Derbyshire are
very numerous, and the organic remains equally so, and of a highly
interesting character.[804]
[804] A good, catalogue of the principal varieties will be found in Mr.
Adams’s pamphlet previously recommended; and specimens may be obtained
at his museum in Matlock, and from Mr. Tennant (Professor of Mineralogy
to King’s College), 149, Strand, London.
This enumeration of the geological formations of which the country
around Matlock is composed will enable us to proceed on our rambles
without further digression, and should the reader be at a loss to
comprehend the nature of any of the rocks or strata we may meet with on
our way, he can refer to the above description.
Mr. Bakewell, with his wonted penetration, first detected the true
character of the stratification of the High Tor, previous writers
having described this cliff as being composed of nearly horizontal
layers. But this is a deceptive appearance; for, although, when viewed
in front, or in the direction of their planes, the strata appear to be
horizontal, yet they are in reality highly inclined, as may be seen in
the line of dip, and enfold or envelope the back of the cliff; and
they are continued into the hill (Masson) on the opposite side of the
valley, where they present a similar arrangement. The continuity of
the strata is broken by the vale of the Derwent, which has evidently
originated in a fissure extending along the axis of elevation, in a
direction from north to south; thus forming the water channel for the
drainage of the country on the north, and the bed of the present river.
We have already pointed out the curved position of the strata on the
face of the _Church Tor_.
[Sidenote: EXCURSION TO CRICH HILL.]
Excursion to Crich Hill.--The appearances observable at the High Tor
are of so striking a character, and involve the consideration of so
many interesting phenomena relating to the physical mutations which
this district has undergone, that it is desirable, while they are
strongly impressed upon the mind, to take an excursion to Crich, a few
miles to the south-east of Matlock. Here there is an entire mountain of
limestone, formed by a protrusion of numerous strata, many hundred feet
in thickness, through the once superincumbent beds of millstone grit
and sandstone, into a dome-shaped mass, upwards of 800 feet high. And
there it stands, a stupendous monument of one of the past revolutions
of the globe, with its arches of rifted rock, supported by a central
mound of erupted mineral matter, now cooled down into an amorphous mass
of compact basalt! Were there no other object of interest near Matlock,
Crich Hill would alone render it worthy of resort.
From the heights above our hotel, looking towards the south-east,
a mountain remarkable for its elevation and obtusely conical
configuration, and distinguished by a tower on the summit, forms a
striking object on the horizon, at an apparent distance of three or
four miles--this is Crich Hill; and on the same range, to the right, is
seen the church-spire of Crich village (see _Lign. 272_).
A long summer’s day is not too long to visit this mountain, and examine
all its interesting details. A good pedestrian should proceed with
his hammer and haversack, for every step of the road is replete with
interest; and as numerous specimens will be obtained, bags, paper, and
boxes should be taken. If an invalid or ladies be of the party, it will
be desirable to have a carriage for the day, and dine at the little
village of Crich;[805] and, if time permit, the interesting ruins of
South Wingfield Manor-House (once the prison of Mary of Scotland),
about two miles from Crich, may also be visited.
[805] A good, guide will be a great acquisition, and save much, time
and trouble; and Benjamin Froggatt, who has conducted Dr. Buckland and
other geologists to the principal localities in the neighbourhood, will
be found an obliging and intelligent attendant, perfectly conversant
with the richest geological and botanical sites around Matlock.
The shortest drive from Matlock to Crich Hill is over Cromford-bridge;
but a far more picturesque route is by the Derby-road to
Whatstandwell-bridge (see _Lign. 273_), and from thence ascending
the hill to Crich, and returning home by Holloway; making the entire
distance about twelve miles. As our immediate object is to examine
the geological features of the mountain, we shall proceed by the
nearest road; and upon reaching Scarthing Rock, turn to the left, by
Wellersley Castle grounds, having on the right a bold escarpment of
mountain limestone, with layers of chert in nodules and amorphous
masses. At Cromford Canal, the limestone suddenly terminates, and
sinks beneath the surrounding alluvial silt of the river valley, and
the millstone grit. We will chip off a few specimens of the chert, to
examine at leisure. Crossing the bridge, the road winds round the foot
of the hills of sandstone, which lie on our left, while on the right
is the valley of the Derwent, and the river is seen here and there
through openings in the copses and hedge-rows, meandering through the
rich meadow-lands of the valley, which are flanked on the west by a
magnificent range of lofty hills, clothed with the luxuriant woods of
Alderwasley. The character of the scenery from this point of the road,
till we ascend the high ground, is faithfully and graphically portrayed
by Mr. Rhodes.[806]
[806] Derbyshire Tourist’s Guide, p. 48.
"The road lies through a beautiful valley by the side of the Derwent;
sloping meadows, crowned high above with a long range of magnificent
woods, skirt the road-side on the left: on the right the river,
pursuing its winding way beneath the umbrageous branches of oak,
ash, alder, hazel, and sycamore, and bubbling as it passes along,
is a beautiful object. About two miles below Cromford-bridge, the
road leaves the more open part of the valley, and plunges into the
thick woods that environ the little hamlet of Lea; a lovely spot,
romantically situated by the side of a sparkling stream, in a deep
hollow, amongst steep hills covered with foliage, and fields of the
freshest verdure. The houses of this secluded village, with the
exception of here and there a comfortable cottage, are handsome
residences, nestling among orchards and parterres of flowers.
Everything was flourishing most luxuriantly; and when we passed
through the place, the hollyhocks, dahlias, and roses were in full
blossom, and gave an extremely bright and cheerful aspect to the
scene. The road continues through _Lea Wood_ to _Holloway_ by a
very steep ascent, and from the toll-gate at the top of the hill it
traverses the side of a mountainous ridge, covered with wood and
intervening rock. The prospect is now magnificent: on the right a
scene of great extent opens to the view, rich in all that constitutes
the highest beauty in landscape. The summits of the two ranges of
hills that form the eastern and western boundaries of the fertile
valley at our feet are here from three to four miles apart; and
the extent from north to south is from ten to twelve. Many minor
eminences, rich with wood and intervening verdure, adorn this
enchanting scene, through which the Derwent, sometimes hidden by
overhanging trees, and sometimes sparkling with light, flows with busy
speed and uninterrupted current by Belper, Milford, and Duffield,
to Derby; the whole presenting an assemblage of splendid scenery
finely diversified and rich in picturesque beauty. The woods of
Alderwasley, that cover the hills from below Whatstandwell-bridge, to
the dark pine-crowned eminence of Stonnis, are peculiarly imposing and
magnificent."
Near the village of Holloway there are several quarries opened on the
side of the hill, which enable us to ascertain that this range is
composed of strata of millstone grit and sandstone, highly inclined
and dipping from the hill. The beds are so split and shattered in
every direction, that no large blocks can be procured, and the stone,
although a good building material, is therefore only employed in the
construction of the cottages and houses in the immediate vicinity. The
_vignette_ of this volume represents a mass of the inclined sandstone
strata near this place. The reader will recollect that the hills on the
opposite side of the valley, on our right, are also composed of similar
strata; and that the ridge, covered with fir-trees, marks the bold
escarpment of the millstone grit at Stonnis, over Cromford; so that the
geological horizon of the valley, as seen from this spot, is wholly
formed by the millstone grits and sandstones. A mile beyond Holloway
toll-gate, the road turns to the left, and the bare dome of mountain
limestone of Crich Hill is before us. We soon arrive at a limestone
quarry, in which the strata are seen to be distinctly arched (see
_Lign. 271_, p. 886), as in the cliff at Matlock _Church Tor_.
We will alight here to examine the rock more closely, and obtain
specimens. Here we see that the strata are inclined both to the right
and to the left, and also lean towards the central axis of the hill
in front of us; presenting such an appearance as would be afforded
by an excavation made in an onion, or other spheroidal body, formed
of a series of concentric layers. The limestone in this quarry is of
the usual subcrystalline character, abounding in shells, principally
_Spirifer_. There are numerous vertical and oblique fissures in the
rock, and these are more or less incrusted with minerals and spars,
which have evidently been deposited by electro-chemical action, and
admirably exemplify the manner in which the rich veins of lead, &c.
are distributed in the strata of the interior of the mountain. In a
crevice of the rock, in which the mineral contents were undisturbed,
the arrangement of the prevailing minerals of this part of Derbyshire,
namely, galena (_sulphuret of lead_), sulphate of barytes (here termed
_cawk_), and fluor spar, was beautifully displayed. A layer of the blue
sulphuret of lead, or galena, was spread over the surface of limestone
forming the walls of the fissure: upon this was a thick stratum of
white sulphate of barytes; and on the latter, fluor spar, of a light
blue colour, forming cubic crystals on the surface nearest the cavity
of the fissure, which therefore appeared to be lined with crystals of
fluor.[807]
[807] The workmen at this and the other quarries generally have
specimens of the fossils and minerals for sale, at moderate prices.
[Sidenote: TRAP OF CRICH HILL.]
About half a mile beyond, we arrive at Wakebridge, near which there
are several very productive lead mines. The "_Glory-mine_," one of
the richest in Derbyshire, is said, some ten years since, to have
been worth from thirty to forty thousand pounds a-year.[808] A mining
establishment, on the left hand, where a powerful steam-engine
is constantly at work, affords numerous specimens of the usual I
Derbyshire spars and minerals; and from among the heaps of refuse
thrown by the visitor may make an interesting collection. Near this
spot, a vertical shaft was sunk in the side of the hill, in search
for lead ore, and at the depth of twenty fathoms, a rock of _compact
Trap_ was reached; the work was continued for a few yards deeper, but
ultimately abandoned as fruitless. A gallery was subsequently driven
into the side of the hill, lower down, and here, too, the trap was
found; thus proving the existence of a central protrusion of igneous
rock, over which the bent strata of mountain limestone are now disposed
in consecutive layers. Numerous blocks of this compact trap or basalt,
some of which are veined with red jasper, lie scattered about the
site of the old shaft, and an interesting suite of specimens may be
collected. Pursuing our way, the limestone strata are seen in openings
on the hill side, having the same remarkable arrangement as those
before described.
[808] Derbyshire Tourist, p. 50.
Upon arriving where the road divides,[809] we must proceed on foot and
visit the quarries, and examine the exposed masses of rock, that we may
clearly comprehend the structure of the mountain. We will now ascend
by the pathway that leads to the summit, and on the left several good
sections of the strata are displayed. On reaching the tower on the
crest of the mountain (_Lign. 272_, p. 887), a magnificent panorama
bursts upon our sight; but which no language can adequately describe.
Here and there bare pinnacles of rifted rock protrude through the green
sward; and masses of white, yellowish, and pink sulphate of barytes,
pyrites, fluor, and other minerals lie strewn upon the surface.[810]
[809] The carriage should here be sent on to the village, and orders
given for refreshments.
[810] Good specimens may often be obtained from the piles of stones,
and from the walls on the side of the hill.
Having reposed for some time at the foot of the tower to enjoy the
glorious prospect spread around us, correct our notes, look over, trim,
and wrap up our specimens, we will now descend to the north-eastern
side of the hill, that the appearance of the strata on that aspect may
also be examined. But ere we leave the summit, again let me call your
attention to its external configuration. Were it not on too extended a
scale, we might suppose that we were standing on an ancient earth-work,
or encampment, formed of limestone, surrounded by a deep fosse or
ditch, and flanked by precipitous embankments of millstone grit and
sandstone, so strongly defined are the physical features of this
remarkable mountain.
We will now visit a large quarry on the eastern side, which presents a
fine section of the limestone strata, above 100 feet thick (see _Lign.
271_), and which, like those we have previously observed, are disposed
in curves, and enfold, as it were, the central axis of the hill; and
the rock is shivered and fissured in every direction. A thick bed of
drift, or alluvial debris, covers the limestone strata, as shown in
_Lign. 271_; and in it, partially rolled blocks of sandstone, some
of them of great size, are imbedded. The direction of the dip of the
strata in this quarry is indicated by the arrows.
[Illustration: _Drawn by Henry Carr, Esq. C. E. del^{t.}_ _J. Whimper,
lign^{t.}_
Lign. 271. Quarry of Mountain Limestone, Crich Hill.]
[Sidenote: VIEW OF CRICH HILL.]
[Illustration: _Drawn by Henry Carr, Esq. C. E._ _J. Whimper, lign^{t.}_
Lign. 272. View of Crich Hill, Derbyshire, from the West.]
Let us now take a retrospect of the facts investigate during this
morning’s ramble, and consider how far Mr. Bakewell’s interpretation
of these phenomena (see p. 879) is in accordance with the data we
have obtained. The outline of Crich Hill, as seen from a moderate
distance, is that of an insulated oblong dome, encircled by precipitous
escarpments, or angular eminences of less elevation. The annexed sketch
(_Lign. 272_), by my friend, Henry Carr, Esq. C.E., of Duffield, to
whom I am also indebted for a survey of Crich Hill, and admeasurements
of the dip of the strata, will render this feature in the physical
geography of the country more apparent.
In _Lign. 272_, the protruded elongated cone of mountain limestone
is denoted by the tower, or _Stand_, on the summit; and the other
heights, and the foreground, are composed of millstone grit and
sandstone. The highest point of limestone is 716 feet above the level
of the Derwent in the adjacent valley; and was estimated by Mr.
Bakewell at about 900 feet above the level of the sea. The hill of
sandstone on the right, on which the mill stands, is 402 feet high,
and conceals Crich village in this view; that in the middle distance,
on the left, marked _a_, is 400 feet high.
This disposition of the millstone escarpments around the central cone
of elevated limestone is shown more in detail in the ground-plan,
_Lign. 273_.
Thus we perceive that the strata of mountain-limestone dip from the
centre of the hill in every direction, as indicated by the arrows, at
various angles, from 20° to 50°; and those of the sandstone hills,
which form an irregular zone around Crich, are also highly inclined,
and in like manner dip from the central axis, as is shown by the
direction of the arrows. Now we know, by observations made in places
where the relative position of the Millstone and Limestone has suffered
no disturbance, that these two series of strata were originally
disposed horizontally and conformably upon each other, thus--
1. _Uppermost_--Millstone Grit and Sandstone.
-----------------------------
2. _Lowermost_--Mountain Limestone.
[Sidenote: GROUND PLAN OF CRICH HILL.]
[Illustration: Lign. 273. Ground Plan of Crich Hill, _Derbyshire_.
(_Scale, one inch to a mile._)
By Henry Carr, Esq. C. E. from actual Survey.]
The area, enclosed within a line, and marked _Stand, Crich Hill_, is
the elevated oblong dome of _limestone_. All the surrounding country
is composed of _millstone grit_ and _sandstone_.
The arrows on the boundary line of Crich Hill denote the direction
of the dip of the limestone strata in nine positions measured and
determined by Mr. Carr. The dip vanes from 20 to 50, the greatest
inclination is on the south-east of the tower.
The arrows on the surrounding millstone escarpments mark the dip of
those strata in a sufficient number of stations, to convey a general
idea of the position of the mountain masses environing Crich Hill.[811]
[811] At Whatstandwell, abridge crosses the Derwent; and dose by, there
is the Bull Inn, where good accommodation and sleeping apartments maybe
obtained.
[Sidenote: CRICH HILL.]
[Illustration: Lign. 274. Section of Crich Hill; from A to B on the
plan, _Lign. 273_.
(_Natural scale._)
By Reginald Neville Mantell.]
A, B.--Strata of _Millstone Grit_, highly inclined, and dipping from the
central axis.
Protrusion of the Mountain Limestone, on the summit of which is
Crich Tower, 716 feet above the level of the river Derwent.
Central mass of Trap, reached by a vertical shaft from
above, and by a gallery on the side of the hill.
It is therefore evident, that at Crich the strata No. 2 must have been
forced up, and protruded through the strata No. 1, or they could not
occupy their present position. We remarked, on ascending Holloway Hill,
the great disturbance which the Millstone beds had sustained (see the
vignette of this volume); and the shaft and gallery near Wakebridge (p.
884) disclosed the existence of a mass of basalt, or _trap_, of unknown
extent, beneath the limestone, in the centre of the mountain; while the
fissures and crevices, filled with metallic ores and spars, attest the
action of intense heat, under great pressure. According to a survey
made by my son, a section in the line marked A--B on the plan, _Lign.
273_, presents the arrangement of the strata seen in _Lign. 274_: the
heights are from actual admeasurements.
From the data thus obtained, we may construct an ideal section in
illustration of these phenomena, as in the following diagram (_Lign.
275_).
Here then, as Mr. Bakewell forcibly observed, "we have cause and effect
in conjunction." Here is the cooled and consolidated molten rock, whose
expansive force elevated the horizontal strata of limestone, and forced
them through the superincumbent beds of grit and sandstone. But this
eruption must have taken place under great pressure, and at the bottom
of the sea; for, had the phenomena been sub-aërial, the result would
have been altogether of a different nature; and we should have had
cooled lava streams, and not masses of basalt.
We have seen that the strata rise round and enfold this central
nucleus of volcanic rock, displaying nearly hemispherical segments
and curves. Now if we suppose a vertical transverse fissure across
such a hill as that represented in the diagram (_Lign. 275_), the face
of the remaining strata would be in every respect similar to that of
the High Tor (see _Lign. 270_, p. 876); namely, a mass of _Trap_, or
_toadstone_, at the base, and a series of arched strata of limestone
above; with fissures containing ores of lead, zinc, barytes, &c. and
various kinds of spar.
[Illustration: Lign. 275. Ideal transverse Section of Crich Hill.]
A, A.--Highly inclined strata of _Millstone Grit_.
B, B.--Arched strata of _Mountain Limestone_.
C.--A central nucleus of _Trap_ or _Toadstone_.
To a mind accustomed to investigations of this nature, a slight
examination of the phenomena under review will, I apprehend, suffice to
demonstrate the correctness of these deductions; but I may have failed
to place the subject before the general reader in an intelligible and
lucid point of view; should this be the case, still, if the attempt
to present a familiar exposition of the physical structure of this
remarkable district shall induce him to visit the scenes I have so
imperfectly portrayed, and interrogate Nature in a right spirit, the
hours we have passed together in our excursion to Crich Hill will not
have been spent in vain; for in the beautiful language of the noble
bard:--
"To sit on rocks, to muse o’er flood and fell,
To slowly trace the forest’s shady scene,
Where things that own not man’s dominion dwell,
And mortal foot hath ne’er or rarely been;
To climb the trackless mountain all unseen,
With the wild flock that never needs a fold;
Alone o’er steeps and foaming falls to lean;
This is not solitude; ’tis but to hold
Converse with Nature’s charms, and view her stores
unroll’d."--Childe Harold, Canto II. xxv.
Specimens of Fossils and Minerals.--On our return, our first care must
be to look over all the specimens we have gathered, arrange them,
and select those which are the most illustrative of the phenomena
we have examined; and ticket every specimen, as recommended in the
Instructions. The fossils, consisting of several species of _spirifer_
and other brachiopoda, and of portions of encrinital stems, require no
particular care. The rocks should comprise specimens of the different
varieties of limestone and sandstone; and of the green limestone,
altered by contact with the toadstone; and examples of the compact
trap, and of the variety veined with red jasper,--of the amygdaloidal
toadstone,--and the vesicular, or that in which the cavities are
empty. The minerals should comprise the ores of lead, zinc, barytes,
fluor, and calcareous spar; of the last some good clear pieces should
be selected, that will exhibit its double refracting property. Of the
common metal, _Pyrites_, a few specimens should be preserved; this
mineral, from its splendid yellow appearance, is often mistaken for
gold; but a mere blow of the hammer will immediately detect it, for
_Pyrites_ is brittle, and readily cracks to pieces, while gold, as is
well known, is remarkably ductile. If the collector be not satisfied
with the fruits of his day’s researches, he should look over the
catalogue of Mr. Adams, and purchase such specimens as will render his
collection sufficiently extensive to present a full illustration of
the geological character of the scenes he has this day visited.
There is a variety of sulphate of barytes from near Youlgreave
exhibited in the shops at Matlock, of which one or two examples should
be obtained. The surface of the polished specimens much resembles the
rich variegated appearance of dark tortoise-shell. This mineral has
been formed, like the common calcareous stalactite, by infiltration
through some porous rock; transverse sections exhibit concentric
layers of various shades; while the longitudinal have the varied
colours disposed like those in tortoise-shell.
* * * * *
[Sidenote: BONSAL VALLEY.]
NOTES FOR A GEOLOGICAL EXCURSION BY CROMFORD, UP BONSAL VALLEY, BY VIA
GELLIA, TO MIDDLETON MOOR; RETURNING BY STONNIS.
This excursion will present many objects of interest, and one day at
least should be devoted to the examination of the different localities
pointed out in the following notes.[812] To Cromford, and then take the
road that leads through Bonsal vale. A fine range of limestone on the
right, and a sparkling stream (Bonsal-brook) on the left. On the banks
of this brook there is a manufactory of mineral colours (Pooley’s)
well worthy a visit. But before we reach this establishment, there is
an opening on the hill side where the strata are exposed, and a bed of
Trap is seen beneath the limestone; near this place specimens of fluor,
calc-spar, &c., that have been thrown out in forming the excavation,
may be collected. From beneath the trap a warm spring issues and flows
into the neighbouring brook.
[812] Benjamin Froggatt should be engaged to conduct the pedestrian;
and a carriage party would also do well to place themselves under his
guidance.
Proceed up the road leading to _Via Gellia_, and through a valley
flanked with high ranges of limestone and dun-stone. On the right,
is the beautiful cascade previously mentioned, near _Dunsley_. This
valley is a celebrated botanical region, for several species of plants
which are of great rarity or unknown elsewhere are here met with. At
the direction post, turn to the left up the steep hill that leads
to Middleton Moor. On each side numerous fossils of the mountain
limestone may be collected from the blocks lying on the flanks of the
hill. Views splendid in picturesque scenery and of a highly interesting
geological character are obtained as we ascend. On the summit of
Middleton Moor, which is from 1,300 to 1,400 feet above the level of
the sea, a most extensive panoramic view of the surrounding country may
be obtained. The geological map will enable the observer to identify
the crags of Charnwood Forest, the High Peak, &c. &c. Almost every part
of the Moor is studded with the disused shafts of exhausted mines, and
which are so carelessly covered over as to be extremely dangerous,
and the visitor must bear this caution in mind; for the heaps of
stone placed at irregular intervals on the hill, and which tempt the
geologist to seek for specimens, are for the most part piled over the
openings of deep shafts.[813]
[813] My son narrowly escaped being drawn in by a heap of stones which
gave way under his feet, and suddenly disappeared in the chasm below.
In rambles of this kind in a mining country, the young geologist must,
therefore, be upon his guard, or he may be engulphed with masses of
limestone in some deep chasm, and his bones, incrusted with stalactite,
form an ossiferous breccia, that in future ages may perplex some
collector of organic remains to determine its relative antiquity!
Pass on by Worksworth, to the quarries of mountain limestone, where the
encrinital marble, so largely employed for side-boards, chimney-pieces,
&c. is procured. Near the approach to the entrance of the quarry,
an instructive example of curved strata of limestone is seen on the
left; and on the right, a fine vertical artificial section. On the
weathered surface of the left side of this entrance, and on the face
nearest the quarry, good specimens of the stems I and ossicula of the
usual Derbyshire crinoidea may be extracted (p. 284) from the layers
of reddish limestone; and good blocks of the marble may be selected.
Large spirifers can be procured from the limestone in these quarries;
the quarry-men often have specimens. On the right hand of the entrance,
layers of flinty slate (called partings of _black bind_ by the miners)
occur between the beds of limestone. In a field near this quarry, on
the left of the road leading to Cromford, where some mining operations
are going on, blocks of the stone called _chert_ have been thrown up,
and often contain beautiful examples of the pulley-stones (p. 285), or
siliceous casts of the stems of the crinoidea. A large collection of
fossils may be gathered in the localities above mentioned.
We now drive to the escarpment of millstone grit at Stonnis, called
_Black-rock_, whose pine-clad summit forms so conspicuous an object
in the view from Crich Hill; it is about a mile from Cromford, and
overlooks Matlock Dale.
On the right of the road, the refuse workings of a mine cover the
side of the hill; among which some specimens of spars or minerals may
perhaps be found.
[Sidenote: VIEW FROM STONNIS.]
But the grand attraction of Stonnis is the view of Matlock Dale and
the surrounding mountains, obtained from the verge of the precipitous
escarpment of sandstone rocks, under the knoll of pines. It is, indeed,
a scene of transcendent beauty and magnificence, and is said, by one
who has ascended every mountain top and traversed every ravine and
valley in this district, to be unrivalled.
"In that species of beauty which in landscape scenery approaches to
grandeur, it is unequalled in Derbyshire. The parts of which it is
composed are of the first order of fine things, and they are combined
with a felicity that but rarely occurs in nature. Scarthing Rock, the
woods of Willersley Castle, Matlock High Tor, the hills of Masson,
Crich, and Riber are all noble objects; and the rude masses that
constitute the foreground of the picture are thrown together, and
grouped and coloured in a manner strikingly picturesque. I have scaled
the highest eminences in the mountainous districts of Derbyshire--seen
from their summits the lovely dales that repose in H tranquil beauty
at their base--marked the multitude of hills included within the
wide horizon they command, and my heart has thrilled with emotion at
the sight; but not an eminence that I ever before ascended--not a
prospect, however rich, and varied, which I thence beheld--is at all
comparable with the view from Stonnis."[814]
[814] Derbyshire Tourist’s Guide, p. 42.
Every one possessed of taste and feeling who gazes upon this glorious
landscape will partake, in a greater or lesser degree, of the emotions
thus finely expressed by the ardent lover of the sublime and beautiful
in nature; but to the natural philosopher the physical characters of
this enchanting region are fraught with a deeper interest, and present
subjects for the most profound contemplation. To him the rocks and the
mountains are the grand monuments of nature, on which are inscribed the
history of the physical revolutions of the globe which took place in
periods incalculably remote and long antecedent to the creation of the
human race. They present to his mind a succession of events, each so
vast as to be beyond his finite comprehension; ages of tranquillity,
with lands and seas teeming with life and happiness, succeeded by
periods in which the earthquake and the volcano spread universal ruin
and destruction--and they teach him that all these awful changes bear
the impress of the Almighty’s hand, and were subservient to the eternal
purpose of rendering this planet the fit abode of man, during his
mortal pilgrimage.
CHAPTER XXV.
NOTES FOR A GEOLOGICAL EXCURSION TO CHARNWOOD FOREST, TO EXAMINE THE
CENTRAL GROUP OF PLUTONIC ROCKS OF ENGLAND; AND THE CARBONIFEROUS AND
CAMBRIAN STRATA, THROUGH WHICH THEY HAVE BEEN ERUPTED.
In the central county of our Island, within a hundred miles of the
Tertiary deposits of the South-east of England, a group of plutonic
rocks emerges from beneath the strata of limestone, coal, and red marl
which constitute the principal geological features of the midland
provinces, and rises up into the bold and picturesque range of hills
of Charnwood Forest. Almost the entire series of British rocks is now
brought by the railroads within a few hours distance of the metropolis;
and the geological inquirer may, in the course of a fortnight, examine
in their natural situations the Eocene deposits of the London and
Hampshire basins--the Cretaceous and Wealden strata of Sussex, Kent,
and Surrey--the Oolitic, Liassic, Triassic, Permian, and Carboniferous
systems--the Mountain limestone and its metalliferous treasures--Traps,
or ancient lavas, and their effects--strata of the Silurian and
Cambrian systems--and, lastly, Granite, Syenite, Porphyry, and other
modifications of the plutonic or igneous rocks. The present notes refer
to two or three days spent in exploring the country around Leicester,
and in examining the granite of Mount Sorel[815]--the slate quarries of
Swithland--the syenitic crags of Bardon Hill--the porphyritic masses
of Markfield and Grooby--and the coal-mines of Whitwick. On our
previous excursion by railway to Leicester (see Excursion to Matlock,
p. 867), the order of the succession of the strata from the metropolis
to that town was described; on this occasion it will only be requisite
to direct the traveller’s attention to the abrupt isolated hills, by
Hinckley, Grooby, and the craggy peaks of Charnwood Forest, in the
distance, on the left of the railroad, before reaching Leicester. If a
pedestrian excursion be resolved upon, three or four days at least will
be required to follow the route presently pointed out; in a carriage
and pair, it may be accomplished in a long summer s day, by starting
from Leicester at six, and returning by ten or eleven.[816]
[815] Sorel, a corruption of _Soar Hill_, or hill on the river Soar.
[816] It maybe well to remind the visitor that at Leicester the
following objects are worthy of notice:--the Roman Milestone, now
placed in the High-street; the remains of the Roman Wall; and the Blue
Boar Hotel, where Richard III. slept the night before the battle of
Bosworth.
[Sidenote: EXCURSION TO CHARNWOOD FOREST]
The geological localities to be visited in this excursion are the
following--
I. Barrow-on-Soar.[817] _Lias limestone._--The quarries at this
locality are celebrated for the organic remains that have from time
to time been obtained from the limestone. Bones of Ichthyosauri and
Plesiosauri (see p. 669), fishes (_Dapedius_, p. 603), leaves of
cycadeæ, and fossil wood, together with ammonites, terebratulæ, &c. may
generally be obtained.
[817] There is a station at Barrow, and the pedestrian may be put down
within a short distance, by the railway.
Although at the very foot of the plutonic rocks, and on the verge of
the grand focus of volcanic action which erupted the syenitic masses
of Charnwood Forest, the strata in this spot appear to have suffered
but little disturbance. But this phenomenon is in accordance with
what occurs in other volcanic districts. For, as M. Constant Prevost
remarks, volcanoes may open across all the strata, without occasioning
great derangements; thus, at Limagne, Aurillac, and Puy (see _Wond._
p. 269), the tertiary strata have preserved their horizontality, even
around the vents through which issued the volcanic matter that covered
those countries with numerous cones of eruption.
II. Mount Sorel. _Granite and Syenite._--The road from Leicester
ascends a ridge of Triassic or New Red strata, called Birstal Hill,
from whence there is a fine view of the town. In the meadows on the
left, some ruined walls, covered with ivy, mark the site, and are the
only remains of the Abbey in which Cardinal Wolsey expired. Approaching
Mount Sorel, an abrupt hill, with a mill on the summit, denotes, from a
considerable distance, the geological character of the spot. There is
a small Inn in the village, where accommodation may be procured. Visit
the quarries, and also the establishment of Mr. Jackson, where the
granite is worked into pillars, side-boards, &c.[818]
[818] An interesting account of this manufactory will be found in Sir
Richard Phillips’s "Personal Tour."
The hill is about 120 feet in height, and 1,400 yards long; and is
estimated to contain about two hundred millions of cubic feet of
workable granite, above the general level of the district.[819]
[819] The granite resembles that of Aberdeen, but contains a larger
proportion of felspar.
III. Swithland. _Slate-rocks._--From Mount Sorel proceed to Swithland:
as we approach the quarries, the employment of slate for every
available purpose, in the footpaths, walls of cottages, &c., indicates
the abundance of this material in the neighbourhood. At Swithland, the
quarries are very extensive, and expose magnificent sections, from 100
to 120 feet thick, of strata of Slate, highly inclined; and forming one
side of an anticlinal axis, the summit of which will be passed over
in our route by Woodhouse. In one quarry, at the time of my visit,
a series of nearly horizontal strata of red marl was exposed, lying
unconformably upon the edges of the highly inclined beds of Slate. The
Slate-rocks of Charnwood Forest have a single anticlinal axis, which
strikes from NN.W. to SS.E.; and the axis of the adjacent coal-field of
Nuneaton has a similar direction.[820]
[820] Murch. Sil. Syst. p. 569.
[Sidenote: WOODHOUSE. BARDON HILL.]
IV. Woodhouse. _Slate-rocks._--From Swithland to Woodhouse, is a
continuation of the highly inclined Slate strata. The village is
romantically situated on the ridge or crest of the anticlinal axis
of Charnwood Forest. On the sides of the road, there are occasional
openings where the strata are exposed. There is, in particular, a fine
section on the sides of the elevated point on which the church and
school are built, lying to the left of the road in the approach from
Swithland. A day might be well spent in this place, and at Swithland.
V. Bardon Hill. _Syenite._--We next proceed to Bardon Hill, ascending
to the highest ridge of the protruded mass of igneous rock, of which
this mountain-range is composed. The craggy and bare pinnacles which
are every where presenting themselves, shooting up, as it were, from
the green sward, cannot fail, from their novel and striking character,
strongly to impress the mind of the young geologist, who now, for
the first time, visits a region of plutonic rocks. The view from the
summit of the hill is grand and imposing; it should be studied with
a geological map of the country before us, that the position of this
central mass of volcanic rocks, and its relation to the surrounding
sedimentary strata, may be fully comprehended.
VI. Whitwick and Snibstone. _Coal-measures._--Spread around the foot
of the Syenitic mountain which we are descending are the coal-bearing
strata of the Carboniferous system; and in the works at _Whitwick_
and _Snibstone_ the geological inquirer can examine the nature of
these deposits in the coal-mines, which he should descend, and obtain
specimens of the strata and fossils from the beds in situ.[821]
[821] Should he be so fortunate as to see the resident engineer
of Snibstone Colliery, Mr. George Vaughan, he will be certain of
meeting with a courteous reception, and every facility for pursuing
his inquiries, descending the shaft, and obtaining fossils. Mountain
limestone is brought to this place to be converted into lime; and good
specimens of shells, encrinites, &c. may sometimes be extracted from
the blocks of stone.
Among the refuse of the workings thrown up from the various shafts,
search should be made for stems of _calamites_ (p. 108), _seed-vessels_
(p. 149), _fern-leaves_ (p. 109), &c.
A section from Whitwick, through Charnwood Forest, to Barrow-on-Soar,
in the direction of the route we have traversed, would give the
following succession of rocks:--1. Whitwick; _Coal-strata_, highly
inclined. 2. _Slate-rocks_ of Woodhouse, highly inclined. 3.
Protrusions of _Syenite_. 4. _Slate-rocks_ of Swithland, highly
inclined, with unconformable strata of red marl. 5. _Granite_ and
_Syenite_ of Mount Sorel. 6. _Red marl_ and _sandstone_, supporting the
_Lias_, at Barrow-on-Soar.
The pedestrian should spend one or two days at Snibstone, where there
is humble, but comfortable accommodation.
[Sidenote: MARKFIELD AND GROOBY,]
VII. Markfield and Grooby. _Syenite and Porphyry_, &c.--These places
may be visited on our way back to Leicester.
[Illustration]
MISCELLANEOUS.
_List of Dealers in Fossils, Minerals, &c._
British Natural History Society, for the distribution of Fossils and
Recent Shells, London Agent for the, 30, Tavistock-street, Covent
Garden.
Charlton, Mr., at the Geological Society’s apartments, Somerset House.
For boards and tablets for fossils; prepared and backed paper for
diagrams; cabinets for specimens, &c. An excellent and intelligent
workman, and moderate in his charges.
Cuttell, Mr., 52, New Compton-street, Lapidary. Prepares fossil teeth,
&c. for the microscope.
Darker, Mr., Lapidary, 9, Paradise-street, Lambeth. Fossil and recent
objects for the microscope. Specimens of the infusorial earths, teeth
of fishes and reptiles, marbles, &c.
Edwards, 40, High-street, Camden Town. For hoards for cabinets, to
affix fossils, shells, &c. instead of trays.
McLellan, 107, Great Russell-street, Bloomsbury. Manufactures the trays
for the British Museum. Wooden trays with black sides, 2 inches by 2,
to 6 inches by 2, price 7_s._ per dozen. This price is much too high,
except for public collections. Common card or pasteboard trays answer
every purpose.
Simmons, Mr., 6, Francis-street, Newington Butts. Collector of fossils;
especially of choice Chalk fossils and fossil Foraminifera.
Sowerby, Mr. G. B. (the eminent naturalist), 50, Great Russell-street,
Bloomsbury. All kinds of minerals, fossils, and recent shells.
Tennant, Mr. J. Professor of Mineralogy and Geology to King’s College,
149, Strand. Every purchasable species of fossil, mineral, or shell may
be obtained; as well as the various microscopic fossils, infusorial
earths, slices of teeth, wood, marble, &c. The collections formed by
Mr. Tennant for the student in Geology, Palæontology, and Mineralogy
are admirably calculated to afford that practical acquaintance with
specimens, so indispensable to the acquisition of a knowledge of
Geology. A series may be obtained, illustrative of the system of
instruction suggested in these volumes, and arranged in a sequence
corresponding to the order in which the fossils are described. The
price of a mahogany cabinet with five trays, containing 200 specimens,
illustrative of the elementary works on Geology, is five guineas:
cabinets with fewer and less valuable specimens from two to three
guineas. The following is an outline of the contents of the five guinea
cabinet--
Minerals which are either the components of Rocks, or occasionally
imbedded in them:--Quartz, Agate, Chalcedony, Jasper, Garnet, Zeolite,
Hornblende, Augite, Asbestus, Felspar, Mica, Talc, Tourmaline,
Calcareous Spar, Fluor, Selenite, Baryta, Strontia, Salt, Sulphur,
Plumbago, Bitumen, &c.
Native Metals, or Metalliferous Minerals; these are found in masses or
beds, in veins, and occasionally in the beds of rivers. Specimens of
the following Metallic Ores are put in the Cabinet:--Iron, Manganese,
Lead, Tin, Zinc, Copper, Antimony, Silver, Gold, Platina, &c.
Rocks; Granite, Gneiss, Mica-slate, Clay-slate, Porphyry, Serpentine,
Sandstones, Limestones, Basalt, Lavas, &c.
Silurian Fossils from the Llandeilo, Wenlock, and Ludlow Rocks.
Secondary Fossils from the Devonian, Carboniferous, Permian, Triassic,
Lias, Oolite, Purbeck, Wealden, and Cretaceous Groups.
Tertiary Fossils from the Thanet Sands, Woolwich and Reading beds,
Bracklesham, Barton, and London Clays, Isle of Wight fresh-water
series, Crag, &c.
Mr. Tennant has also models of many unique and rare fossils; as for
example, teeth, horn, claw-bones, &c. of the Iguanodon; lily encrinite;
small models of the upright coal-trees, near Bolton; of the magnificent
Plesiosaurus of Mr. Hawkins’s collection, now in the British Museum
(price 4_l._ 4_s._); Mr. Sopwith’s models of stratification, &c.
Topping, Mr. 1, York-place, Pentonville-hill; supplies boards and
cases, and every kind of fossil infusoria, &c.; polished slices
of fossil wood and teeth; and all kinds of microscopical objects,
admirably prepared, and at moderate prices.
British Museum.--Models of some of the most remarkable fossils in the
National Collection (a list of which is published in the "Synopsis of
the British Museum ") may be purchased of the _Formatore_.
Microscopes.--A microscope is now an indispensable instrument for the
collector of fossil remains; and, in fact, for the cultivator of any
natural science. A microscope sufficient for every useful purpose may
be obtained, at the price of from seven to twenty guineas, of--
Poulton, Mr. C., Wooburn, near Marlow, Bucks; beautiful preparations
of minute fossil animal and vegetable structures for the microscope at
1_s._ 3_d._ per slide. Infusorial earths admirably prepared. Specimens
of foraminifera, recent and fossil. Grignon sand with, foraminifera, &c.
Powell, Mr., 24, Clarendon-street, Clarendon-square.
Pritchard, Mr. Andrew, Fleet-street; the author of various useful works
on microscopical subjects. Mr. Pritchard’s microscope, of from seven to
ten guineas, has been purchased by several of my geological friends,
and admirably answers the purpose of investigation.
Ross, Mr. 21, Featherstone-buildings, Holborn; justly celebrated for
the perfection of his instruments.
Smith and Beck, Messrs. 6, Coleman-street, City.
BRIGHTON.
Nightingale, Mr. 52, Frederick-street, near the railway station
Brighton A large assortment of Sussex chalk and other fossils. Mr.
Nightingale is a first-rate artist in clearing chalk fishes and
crustaceans.
Thatcher, Mr., West Cliff, King’s-road, has often very choice chalk
fossils, admirably cleared, and at fair prices.
Most of the pebbles cut and set in brooches, and sold by the lapidaries
and jewellers in this town, as Brighton common German moss-agates. The
green brooches called _Brighton aqua marines!_ are rolled fragments of
bottle-glass. Occasionally good sections of the _Choanites_ (see p.
234) may be obtained: inquire for "_petrified sea-anemones_."
CHIPPENHAM, WILTS.
Buy, William; for Oxford Clay fossils of the greatest variety and in
the highest perfection. Especially celebrated for his discovery and
admirable development of the soft parts of Belemnoteuthides, Belemnites
with phragmocones, &c.
DOVER.
Griffiths, Paradise-street.
Moses, Stroud-street; has generally a large collection of Chalk and
Galt fossils.
HASTINGS.
Bissenden, Thomas, West-street; Oliver, Elizabeth, 7, Parade; of whom
Wealden fossils from the neighbouring cliffs may often be obtained.
RYDE, ISLE OF WIGHT
Fowlstone, Mr., 4, Victoria Arcade.
SHEERNESS.
Hayes, Patrick, Sheppey-street, Blue Town. The usual Sheppey fossils.
According to his own list, he has for sale,--petrified whelk-shells,
cockles, clams, screws, Nautilus. Fruits, various; as beans, coffee,
figs nuts. Crabs, lobsters, turtles. Fishes' heads, teeth, and
spine-bones. His charge for perfect specimens is high; a Nautilus,
cut in half and polished, presenting two perfect sections, 25_s._; if
imperfect, 1_s._ or 2_s._ A fish’s head, or lobster, 10_s._ to 15_s._;
imperfect examples, 6_d._ to 2_s._; see p. 840.
VENTNOR, ISLE OF WIGHT.
Wheeler, Charles, Holder’s Sea-side Cottage. An excellent guide to the
most interesting localities along the southern shore of the island.
Collects and sells specimens.
WARMINSTER.
Baker, Mr.; dealer in fossils. The Warminster Greensand, and Chalk
fossils.
WEYMOUTH.
Damon Mr. Robert, dealer in fossils; has always on sale a large and
excellent collection of the organic remains from the neighbourhood of
Weymouth, the Isle of Portland, and Lyme Regis, &c. A series of recent
British shells, from 200 to 400 species, correctly named.
YORK.
British Natural History Society, for the distribution of Fossils and
recent shells; conductor, &c. Mr. Charlesworth, Curator of the York
Museum.
* * * * *
Notes on the Prices of Fossils.--A Short communication by the Author to
Charlesworth’s London Geological Journal, No. I. p. 13, contains a list
of the prices of several interesting fossils and collections of fossils.
* * * * *
Minerals.--A complete series of the minerals of Cumberland comprising
specimens of great beauty and interest, can be obtained of John Cowper,
Alston, Cumberland; he may be relied upon for his knowledge and
attention, and his prices are moderate.
GENERAL INDEX.
GENERAL INDEX.
A.
Abies, 177.
Abietites Dunkeri, 179.
Acalephæ, 280, 772.
Acanthoteuthis furiosa, 447, 462.
Acephala, 375.
Acetabulifera, 449.
Achilleum, 223.
Acorn-shell, 506.
Acrocidaris nobilis, 319.
Acrodont reptiles, 648.
Acrodus nobilis, 584.
Acrogens, 60.
Actibatis, 753.
Actinia, 254.
Actinocrinites, 287, 294, 295.
Actinocrinus Parkinsoni, 294.
Agassiz, M., on cololites, 622.
--------------- Fishes, 563, 568, _et passim_.
Age of Reptiles, 644.
Air-bladder of Fishes, fossil. 620.
Aix, fossil insects from, 557.
Aix-la-Chapelle, 205.
Aix, Provence, 185, 199, 550, 557, 625, 628, 731.
Alabama, United States, 780.
Alcyonium, 254.
--------- chonoides, 247.
Algæ, fossil, 87.
Allanbank, Berwickshire, 167.
Allesley, near Coventry, 124.
Alligator Hantoniensis, 676.
Alloa, Scotland, 778.
Allport, Mr. D., researches of, 789.
Alum Bay, Isle of Wight, 73, 175, 421, 847.
--------, lignite at, 73.
Amber, 52, 182.
Amblypterus, 601.
Ammonites communis, 477.
--------- Dufrenoyi, 476.
--------- Jason, 479.
--------- lautus, 476.
--------- varians, 476.
--------- Walcottii, 397, 482.
Ammonitidæ, 469, 476.
Amorphozoa, 219.
Amphigens, 61.
Amphitherium Broderipii, 806.
Analysis of Molluskite, 433.
Ananchyte, flint-cast of, 320.
Ananchytes ovatus, 323, 327.
Ancyloceras furcatum, 484.
----------- gigas, 485.
Angers, 537.
Angiosperms, fossil, 197.
Animal Kingdom, classification of, 217, 826.
Animal remains, fossil, 43.
Annelida, 503.
Anning, Miss M. researches of, 48, 464, 596.
Annularia, 146, 147.
Anomopteris Mougeotii, 117.
Anomura, 512.
Anoplotherium commine, 789.
------------- secundarium, 790.
Anstice, Mr., researches of, 555.
Antholites liliaceus, 198.
Anthophyllum Atlanticum, 257, 262.
Anthozoa, 253.
Anthracotherioid pachyderms, 791.
Anthracotherium, 790.
Antigua, 185, 264.
Apateon pedestris, 745.
Ape, fossil, of France, 814.
Apiocrinites, 286, 288, 291.
Apiocrinus ellipticus, 290.
---------- flexuosus, 291.
---------- Parkinsoni, 288.
---------- rotundus, 289.
Aporrhais, 426.
Aptychus sublævis, 492.
Arabia, 362.
------, foraminifera-rocks in, 362.
Arachnida, 550.
Araucaria peregrina, 175.
Araucarites, 168.
Arborescent ferns, fossil stems of, 122.
Archæocidaridæ, 322.
Archæoniscus Brodiei, 521.
Archegosaurus Dechenii, 745.
------------- lucius, 745.
------------- minor, 745.
Argonaut, 450, 465.
Arkansas, United States, 780.
Armagh, Ireland, 595.
Artisia, 168.
Asaphus, 536.
Aspidorhynchus, 617.
Astacidæ, 515.
Asteracanthus, 581.
Asteriadæ, 280, 301.
Asterias arenicola, 307.
-------- prisca, 308.
Asteroida, 254.
Asterolepis, 619.
Asterophyllites, 145.
--------------- equisetiformis, 147.
Astræa ananas, 262.
------- pentagona, 262.
------- Tisburiensis, 263.
Atherfield, 518, 529.
Aust Cliff, 560, 588, 805, 865.
Austen, Mr. R. A. C., researches of, 850, 861.
Austin, Messrs., on crinoidea, 288.
Australia, 803, 809.
Autun, France, 130, 178.
Auvergne, 529, 560, 765.
Ava, Burmah, 185, 278, 794.
Avicula inæquivalvis, 404.
Aylesbury, 481, 498, 863.
Aymestry, 393, 405.
B.
Babbicombe, Devon, 259, 261.
Bacillaria, 88, 91.
Bacton, Suffolk, 803, 811.
Baculites baculoides, 486.
Bailey, Dr., on diatomaceæ, 93, 337.
----------- on foraminifera, 364.
----------- on recent shelly sandstone, 387.
----------- on the mixture of marine and fluviatile species in the
Hudson River, 100.
Bain, Mr. A. G., fossil reptiles in South Africa, discovered by, 714.
Baker and Durand, Messrs, researches of, 814.
Bakewell, Mr., the researches of, 737, 878, 887.
Balanidæ, 506.
Balanus tesselatus, 507.
Balcombe, 851.
Bann River, Ireland, diatomaceæ from the banks of the, 94.
Banwell, Somerset, 783, 809, 811, 816, 865.
Bardon Hill, 901.
Barnacles, 506.
Barr, Staffordshire, 537.
Barrande, M., on trilobites, 534, 541.
Barrow-on-Soar, 669, 899.
Bath, 397, 864.
Batrachia, 646, 739.
Batrachnis, 753.
Batracholites, 740.
Bats, fossil, 813.
Bavaria, 423, 787.
Bay of Fundy, Nova Scotia, upright fossil trees on the cliffs of the, 128.
Beachy Head, 481.
Bean, Mr., researches of, 526, 531.
Bears, fossil, 811.
Beauvais, France, 451.
Beaver, fossil, 803.
Beccarius, foraminifera first discovered by, 339.
Beckles, Mr., researches of, 529, 773.
Belemnitella mucronata, 451, 457.
------------ quadrata, 451.
Belemnites bipartitus, 453.
---------- dilatatus, 451, 458.
---------- lanceolatus, 459.
---------- Listeri, 453, 458.
---------- Puzosianus, 454.
---------- semicanaliculatus, 453.
Belemnoteuthis antiquus, 459.
Belfast, 71, 236.
------- Lough, peat in, 71.
Belgium, 191.
Bellerophon bilobatus, 465.
----------- costatus, 465.
Beloptera belemnitoides, 463.
Belosepia sepioides, 463.
Beloteuthis subcostata, 463.
Benett, Miss E., researches of, 41, 231.
Bensted, Mr. W. H., researches of, 269, 409, 434, 732.
Bergh-mehl of Norway, 96.
Bergmann on fossils, 17.
-------- on the solubility of silex in water, 42.
Bermudas, 274.
Berry Head, Torbay, 764.
Beryx Lewesiensis, 624.
----- microcephalus, 624.
----- radians, 624.
----- superbus, 624.
Bexhill, Sussex, 519.
Bexley, 395.
Beyrichia, 526.
Bidford, Warwickshire, 560.
Bignor, Sussex, 232.
Bilin, diatomaceous deposit at, 96.
Binfield, Mr., researches of, 549.
Binney, Mr., on stigmaria, 136.
Binstead, Isle of Wight, 423, 790, 816, 847.
Binstwick, Holderness, 95.
Binton, Warwickshire, 552.
Bird-like bipeds, imprints of feet of, 768.
Birds, 759, 763.
Bivalve mollusks, the parts of, 377.
Blackdown, Devon, 350, 411, 413.
Bleadon, Somerset, 811.
Bletchingley, 406, 458.
Bognor, Sussex, 175, 193, 235, 405, 407.
Bohemia, 96, 539, 623.
-------, diatomaceous deposit in, 96.
Boiling springs, 40.
Bolton, Lincolnshire, 367.
Bombay, 741.
Bonchurch, Isle of Wight, 162.
Bone-breccia of the caverns, 808.
Bone-caverns, 764, 808, 821.
Bones, fossil, 45.
Botanical principles, 58.
Botany, fossil, 51.
Bothrodrendron, 144, 145.
Boughton, near Maidstone, 811.
Boulogne, 398, 412.
Bourgueticrinus, 286, 291.
Bournemouth, Hants, 200, 560.
Bovey Heathfield, Devon, 72.
-----------------------, lignite at, 72.
Bowerbank, Mr., excursions to Sheppey and Bracklesham by, 840, 844.
--------- on carcharodon, 593.
------------ flint, 354.
------------ fossil bird from Sheppey, 768.
------------ fossil fruits from Sheppey, 53, 187.
------------ moss-agates, 103.
------------ pterodactyles, 726.
Bowman, Mr., on sigillaria, 127.
Brachiolites, 226.
------------ angularis, 267.
Brachiopoda or Palliobranchiata, 376, 388.
Brachyura, 511.
Bracklesham Bay, 175, 193, 264, 367, 383, 405, 463, 470, 589, 597, 677,
738, 844.
Bradford encrinite, 290.
Bradford, Wilts, 288.
Branchiopoda, 525.
Brazils, 625, 808, 814, 815.
Brebisson on diatomaceæ, 88.
Brentford, 783.
Brickenden, Capt., researches of, 693, 720, 749.
Bridgewater Essay, Dr. Buckland’s, 8, 22, _et passim_.
Brighton, 99, 224, 230, 232, 233, 289, 299, 348, 368, 384, 408, 451,
458, 628, 778, 783, 795, 852.
--------, diatomaceæ at, 99.
-------- fossil whale, 778.
Bristol, 585, 591, 713, 864.
British localities of fossil cephalopods, 499.
---------------------------- crustaceans, 546.
---------------------------- fishes, 640.
---------------------------- mammals, 818.
---------------------------- plants, 213.
---------------------------- reptiles, 756.
---------------------------- shells, 443.
---------------------------- zoophytes, 278.
---------------------------- fossil monkeys, 815.
British Museum, fossils in, 75, 141, 282, 288, 333, 389, 411, 630, 637,
670, 678, 681, 683, 685, 770, 784, 786, 807, 810.
-------------- strata, synopsis of, 23.
Brittle-worts, 88.
Broderip, Mr., researches of, 806.
Brodie, Rev. P. B., researches of, 521, 549, 552, 556.
Bromley, Kent, 395, 406.
Brongniart and Cuvier on fossils, 18.
Brongniart on asterophyllites, 146.
------------- Crustacea, 533.
------------- moss-agates, 103.
------------- psarolites, 124.
------------- sigillaria, 132.
------------- stigmaria, 134.
------------- the classification of plants, 61.
------------- the distribution of fossil plants, 208.
Bronteus flabellifer, 539.
Brook Bay, Isle of Wight, 164, 170, 178, 415, 695, 701, 848.
Brora, Scotland, 408.
----- oolite, 28.
Brown-coal, 71.
Brown, Dr. R., on triplosporites, 142.
----- Mr. J., researches of, 803, 811.
----- Mr. R., on stigmaria, 137.
Brunswick, 292.
Brussels, 191, 730.
Bryansford, near Newcastle, 95.
Bryozoa, 253, 265.
Buckland, Rev. Dr. Bridgewater Essay, 8, 22, _et passim_.
------------------ on belemnites, 456.
------------------ carpolites, 193.
------------------ cave-bones, 810.
------------------ cephalopoda, 481.
------------------ coal, 84.
------------------ coprolites, 621.
------------------ fossil bird’s-bones, 765.
------------------ insects, 551.
------------------ geoteuthis, 464.
------------------ ichnolites, 770.
------------------ ichthyopatolites, 632.
------------------ Kirkdale Cave, 808.
------------------ Mantellia, 156.
------------------ on marsupialia, 806.
------------------ megalosaurus, 687.
------------------ megatherium, 798.
------------------ paramoudra, 236.
------------------ pterodactyles, 725.
------------------ Reliq. Diluv., 809.
------------------ trilobites, 534.
Buckman, Prof., researches of, 552.
Buenos Ayres, 799.
Bufonites, 604.
Bulimus, 423.
Bumastus, 437.
Buprestis Bucklandi, 554.
Burdie House, near Edinburgh, 79, 113, 524, 531, 602, 617.
------------, fresh-water coal at, 79.
Burham, Kent, 712, 732.
Burmeister, M., on trilobites, 534, 540.
Buy, Mr. W., researches of, 863.
C.
Caddis-worms, fossil, 559.
Caen, Normandy, 679, 680.
Caithness, 614.
Calamites approximatus, 108.
--------- decoratus, 107.
--------- radiatus, 108.
Calamodendron, 146.
Calbourn, Isle of Wight, 423, 847.
Calceola, 392.
Caine, Wilts, 313, 315, 397, 864.
Calymene Blumenbachii, 535.
Cambrian rocks, lower, 34.
Cambridge, 518, 711, 730.
Cambridgeshire, 95, 367, 811.
-------------- fens, diatomaceous deposits in the, 95.
-------------- fossil foraminifera of the, 367.
Camel, fossil, 784.
Campilodiscus, 347.
Cannel-coal, 71.
Cape Breton, Nova Scotia, 137.
Cape of Good Hope, 536, 714.
Caradoc Sandstone, 33.
Carboniferous Flora, 209.
------------- series, 31.
--------------------, foraminifera of the, 365.
Carbonized remains of mollusks, 432.
Carcharodon productus, 591, 593.
Carcharopsis prototypus, 595.
Cardinia, 414.
Cardiocarpon acutum, 147.
Cardium edule, 386.
Carluke, Lanarkshire, 746.
Carnivora, fossil, 807.
Carpenter, Dr., on the structure of nummulites, 345.
---------------------- structure of shells, 390.
Carpolithes Bucklandi, 149.
----------- ovulum, 196.
----------- Smithiæ, 202.
Carr, Mr. H., researches of, 858, 889.
Carrington Park, Devon, 365.
Carter, Mr. H. G., researches of, 362.
----------------- on foraminifera-rocks in Arabia and India, 362.
Caryophyllia annularis, 258, 262.
------------ centralis, 257, 268.
Castle Comb, near Bath, 774.
Castor, fossil, 803.
Catenipora escharoides, 259.
Catillus, 402.
Caulopteris macrodiscus, 123.
Cautley, Capt., discoveries by, 674, 784, 786, 797, 814.
Cave-bones, 764, 808.
Cavern of High Tor, Matlock, 876.
Caverns, Ornitholites of the, 764.
Cellepora, 385.
Cellular plants, 59.
Cement, 816.
Cephalaspides, 610.
Cephalaspis Lyellii, 610.
Cephalopoda, 378, 447.
Ceratiocaris, 525.
Ceratites, 483.
Ceratodus emarginatus, 587, 598.
Cerigo, 808.
Cerithium lapidum, 418, 425.
Cestracion canaliculatus, 580, 584.
Cetacea, 777.
Cetiosaurus, 682.
Cette, 765, 808.
Chæropotamus, 791.
Chalk and flint, microscopical examination of, 371.
Chalk animalculites, 353.
----- detritus at Charing, 363.
----- formation, 25.
----- dicotyledons in the, 205.
----- fossil wood in the, 173.
----- sponges in, 222.
Chara helicteres, 196.
----- medicaginula, 196.
Charing, Kent, 342, 363, 579.
-------, chalk-detritus at, 363.
Charlesworth, Mr., researches of, 226, 709, 805.
Charlton, Kent, 317.
Charmouth, Dorset, 193, 293, 304, 459.
Charnwood Forest, 868.
Cheddar, Somerset, 866.
Cheiroptera, fossil, 813.
Cheirotherian tracks, notices of, 750.
Cheirotherium Hercules, 753.
------------- Kaupii, 752, 753.
Chelichnus, 753.
Chelone Bellii, 734.
------- Benstedi, 732.
------- costata, 735.
------- Mantelli, 735.
------- pulchriceps, 734.
Chelonia, 646, 726.
Chelsea Hospital, fossils in pavement of, 476.
Cheltenham, 397.
Chemnitz, Saxony, 123.
Chenendopora fungiformis, 228.
Chichester, 224, 268, 347.
Chippenham, Wilts, 313, 317, 492, 863.
Chipping Norton, 682.
Chiton, 430.
Choanites Kœnigii, 233.
--------- turbinatus, 243.
Chomle, Bohemia, 550.
Chondrites Bignoriensis, 102.
Christian Malford, Wilts, 454, 459.
Chronological arrangement of the British strata, 23.
Cidaris Blumenbachii, 317, 397.
------- clunifera, 319.
------- cucumifera, 319.
------- intermedia, 316.
------- meandrina, 319.
------- Parkinsoni, 319.
------- sceptrifera, 319.
------- spinosa, 319.
------- stemmacantha, 319.
Cidarite, impression of, on flint, 320.
Cidarites of New Zealand, 318.
Cidaritidæ, 314.
---------- palæozoic, 321.
Ciliobrachiata, 266.
Cirripedia, 505.
Clacton, 817.
Classification of fossil cephalopods, 494.
----------------- plants, 69.
----------------- strata, 23.
----------------- the Animal Kingdom, 217, 826.
Clathraria Lyellii, 159.
Clathropteris meniscoides, 121.
Claycross, near Chesterfield, 127.
Clayton, Sussex, 408, 426, 429, 459, 471, 487, 851.
Clermont, Auvergne, 529.
Clifton, near Bristol, 260, 263, 864.
Clionites Conybeari, 238, 403.
--------- Inoceramus, shell perforated by, 403.
Club-mosses, 140.
Clymenia Sedgwickii, 473.
-------- striata, 473.
Clypeastridæ, 322.
Clypeidæ, 322, 325.
Clypeus sinuatus, 325.
Clove-encrinites, 297.
Cnemidium astrophorum, 227.
Coal, Bovey, 72.
---- brown, 71.
---- cannel, 71.
---- field, stratification of a, 80.
---- formation, 31.
---- measures, 31.
---- nature and geology of, 76.
---- of the Wealden, 73.
Coalbrook Dale, 140, 144, 210, 414, 522, 552, 555.
Cocconeis, 91.
Coccosteus oblongus, 613.
Cœlacanthi, 618.
Cœlodont lizards, 648.
Colchester, Mr., researches of, 805, 815.
Coles, Mr. H., on the skin of the Ichthyosaurus, 670.
Collecting and arranging fossil shells, directions for, 441.
---------- and developing fossil fishes, 635.
---------- remains of mammalia, 815.
---------- and preserving fossil leaves and fruits, 53.
---------- fossil bones, 45.
---------- cephalopoda, 496.
---------- corals, 276.
---------- Crustacea, 544.
---------- echinodermata, 331.
---------- insects, 560.
---------- plants, 211.
---------- remains of birds, 773.
---------- remains of reptiles, 753.
Cololites, 621.
Colossochelys atlas, 732.
Comatula, 286, 302.
Confervæ, fossil, 100.
Confervites Woodwardii, 101.
Coniferæ, fossil, 164.
-------- structure of, 57.
Coniferous forests, petrified, 169.
---------- wood, fossil, 167.
----------------------- in the Chalk-formation, 173.
----------------------- in the Oxford Clay, 172.
Conularia, 417.
Conus tuberculatus, 427.
Conybeare, Rev. W. D., researches of, 404, 663.
Cooksbridge, Sussex, 527.
Copford, Essex, 812.
Coprolites, 432, 621.
Coral-rag, 27, 263, 862.
Corals, fossil, in iron-ore, 265.
-------------- of Babbicombe, 258.
----------------- Clifton, 260.
----------------- Dudley, 261.
------, growth of, 252.
Corax pristodontus, 595.
Corfe, Dorset, 560.
Cornbrash, 28.
Corncockle Muir, 753.
Cornua Ammonis, 476.
Corsica, 808.
Corydalis Brongniarti, 554.
Cotta on fossil fern-stems, 124.
Couvin, Belgium, 459.
Cowes, 847.
Crabs, fossil, 511.
Craigleith, near Edinburgh, 167.
Crania, 392.
Creech, near Corfe, 560.
Creseis, 417.
Cretaceous formation, 25.
-------------------- fossil plants of the, 173, 205.
-------------------- zoophytes of the, 274.
Crich Hill, 880, 883.
Crinoidea, 280, 281, 309.
Crioceras Puzosianum, 484.
Crisia Johnstoniana, 269.
Cristellaria rotulata, 342, 348.
Crocodilia, 646, 673.
Crocodilus champsoïdes, 676.
---------- Hastingsiæ, 676.
---------- Spenceri, 676.
---------- toliapicus, 676.
Cromford, Derbyshire, 285.
Croydon, 838, 849.
Crustacæ, 508.
-------- Ichnolites of, 543, 749.
Cryptobranchus Scheuchzeri, 741.
Cryptogamia, 58.
Ctenacanthus, 581.
Ctenoid fish, 568, 623.
Cuckfield, 160, 755, 851.
Cucumites variabilis, 188.
Cummingston, near Elgin, 749.
Cunningham, Mr., researches of, 750, 751, 772.
Cupanoides lobatus, 189.
Cup-encrinite, 295.
Curculioides Ansticii, 555.
------------ Prestvichii, 555.
Cushion-star, 301.
Cuttle-fish bone, 449.
----------- fossil, 447.
Cuvier and Brongniart on fossils, 18.
------ Baron, discoveries of, 766, 789, 804, 806, 813.
Cyathocrinites, 287, 295.
Cyathocrinus planus 289, 296.
------------ tuberculatus, 286.
Cyathophyllum dianthus, 261.
------------- turbinatum, 261.
Cycadeæ, 150.
------- fossil stems of, 156.
Cycadites megalophyllus, 157.
--------- microphyllus, 158.
Cycas revoluta (recent), 150.
Cyclas, 416.
Cyclobatis oligodactylus, 579.
Cycloid fish, 568, 625.
Cyclopteris trichomanoides, 114.
Cyphosoma, 318.
Cyprella, 532.
Cypresses, fossil, 180.
Cypridella, 532.
Cypridina, 532.
Cyprinoid fish, 627.
Cypris faba, 529.
------ Fittoni, 527.
------ granulosa, 527.
------ tuberculata, 527.
------ Valdensis, 527.
Cyrena, 416.
Cystidea, 298.
Cystiphyllum, 261.
Cythere, 531.
Cythereis, 531.
D.
Dadoxylon, 168.
Dallards, Wilts, 521.
Dana on Silicification, 38, 42.
Dana’s Mineralogy noticed, 9.
Dapedius, 603.
Daphnoidia, 532.
Darling Downs, Australia, 803.
Darmstadt, 787.
Darwin, Mr. C., researches of, 506, 508, 798.
Dawson, Mr. J., researches of, 747, 748.
Deane, Dr. J., on ornithoidichnites, 769.
----- Mr., researches of, 241, 359.
Debey, Dr., on fossil plants from Aix-la-Chapelle, 205.
Deddington, Oxon, 680.
Deer, fossil, 783.
De la Beche, Sir H., the works of, referred to, 833.
Delesserites Lamourouxii, 103.
Dendrerpeton Acadianum, 746.
Dendrodus, 618.
Denny on fossil stems in the Coal, 143.
Deposition of the Coal-measures, 79.
Derbyshire, 284, 407, 414.
Dercetis elongatus, 622.
Dermal bones of reptiles, 657.
------ covering of Glyptodon, 799.
Derry, Tyrone, 531.
Derwent Valley, Australia, 171.
Desmeopora semicylindrica, 271.
Desmidiæ, 88.
Devonian formation, 31.
-------- fossil plants, 212.
Diadema rotulare, 316, 318.
Diamond, 52.
Diatomaceæ, fossil, 88, 93.
---------- recent, 91.
---------- the food of mollusks, &c., 99.
Dibrachiata, 449, 450.
Dichobune, 791.
Dichodon, 791.
Dicotyledonous plant-remains of the Chalk-formation, 215.
-------------- trees, fossil, 203.
Dicotyledons, 59.
Dictyophyllum crassinervum, 198.
Dicynodon Bainii, 717.
--------- lacerticeps, 716.
--------- strigiceps, 717.
--------- testudiceps, 717.
Didelphys, fossil, of Montmartre, 804.
--------- Colchesteri, 805.
Dieffenbach on the Flora of New Zealand, 210.
Dimyaria, 404.
Dinornis, 763.
Dinosauria, 646, 684.
Dinotherium Kaupii, 787.
Diogenes’ lantern, 312.
Diplograpsus, 256.
Diprion, 256.
Dirt-bed in the Purbeck strata of the Isle of Portland, 156.
Discoidea castanea, 324.
Dithyrocaris, 525.
Dixon, Mr. F., fossils and work of the late, 271, 330, 385, 518, 584,
631, 673, 738.
Dixonfold, near Manchester, 125, 137.
Dodo, 763.
Dolichosaurus longicollis, 711.
D’Orbigny. M., restoration of the Belemnite by, 453.
--------- on foraminifera, 339.
Dormouse, fossil, 802.
Dover, 228, 230, 241, 268, 270, 355, 396, 858.
Dracæna Benstedi, 194.
Draco volans, 723.
Drift deposits, 23.
Dudley, Staffordshire, 262, 533.
------ limestone, 33, 261, 272.
Dujardin, M., on foraminifera, 339.
Dumarest, M., on fossil Crustacea, 510.
Dumbleton, 560.
Dumfries, 730, 750, 753.
Dunmore Cliff, Isle of Wight, 398.
Dun-stone of Matlock, 878.
Durlstone Bay, Purbeck, 196, 522, 557.
E.
Ear-bones of fishes, 574, 639.
------------ whales, 778.
East Cliff Bay, Isle of Wight, 195.
East Thickley, Durham, 602.
Eastware Bay, Kent, 480.
Echinidæ, 280, 311.
Echinus, 318.
Edaphodon leptognathus, 589.
--------- Mantelli. 588.
Edentata, fossil, 798.
Edinburgh, 622.
Edwards, Mr. F., on the siphuncle of the Nautilus, 467.
Egerton, Sir P. G., researches of, 579, 584, 590, 599, 601, 604, 667,
670, 750, 809.
Eggs, fossil, 739, 764.
Egra, Bohemia, 96, 182, 347.
Egypt, 170, 345.
Ehrenberg on infusoria, 88.
------------ the Chalk microzoa, 353.
------------ Polierschiefer of Bilin, 96.
Eifel, 258, 392, 430, 539, 741.
Eisleben, Saxony, 602.
Elasmodus, 590.
Elbersreuth, Bavaria, 474.
Elements of Geology, Sir C. Lyell’s, 10, _et passim_.
Elephants, fossil, 785, 817.
Elephas Ganesa, 785.
------- primigenius, 794.
Elgin, 645, 720, 730.
Emydidæ, 727, 736.
Emys, 727.
Enaliosauria, 616, 662.
Encephalous mollusks, 378.
Enchodus halocyon, 630.
Encrinus liliiformis, 286, 292.
Endogenites erosa, 163.
Endogenous stems, 56.
Endogens, 59.
Enniskillen, Earl of, researches of, 520.
Enoploclytia Leachii, 516.
------------ Sussexiensis, 517.
Enoploteuthis, 462.
Entomoconchus, 532.
Entomostraca, 522.
Entrochites, 284.
Eocene deposits, 24.
Epplesheim, 783, 787.
Equisetaceæ, 104.
Equisetites columnaris, 105.
Equisetum Lyellii, 105.
Equus plicidens, 797.
Eschara, 267.
Estheria, 526.
Etyus Martini, 513.
Eugeniacrinus, 288, 289, 297.
Eunotia, 92.
Euomphalus pentangulatus, 428.
Eurypterus, 524.
Excursions, geological, 829.
---------------------- to Bracklesham Bay, 844.
------------------------- Brighton, 849.
------------------------- Bristol, 864.
------------------------- Charnwood Forest, 898.
------------------------- Chippenham and Caine, 863.
------------------------- Clifton, 864.
------------------------- Crich Hill, 880.
------------------------- Farringdon, 859.
------------------------- Isle of Sheppey, 838.
------------------------- Isle of Wight, 847.
------------------------- Matlock, 867.
------------------------- Middleton Moor, 894.
------------------------- Rottingdean, 852.
------------------------- Swindon, 862.
Exogenous stems, 56.
Exogens, 59.
Exogyra, 398.
Extremities of Iguanodon, 700.
----------- Reptiles, 657.
Eye of Ichthyosaurus, 664.
F.
Faboidea bifalcis, 188.
-------- semicurvilinearis, 188.
Fairies’ night-caps, 315.
Fairy-loaf, 327.
Fairy-stones, 284.
Falconer, Dr., discoveries by, 674, 784, 786, 797, 814.
Farnham, Surrey, 233.
Farringdon, Berks, 226, 262, 273, 277, 317, 318, 859.
----------, fossil zoophytes from, 226.
Favosites Gothlandica, 259, 262.
--------- polymorpha, 258.
Favularia, 143.
Felixstow, 778.
Fenestella, 270.
Ferns, fossil, 109.
----- fossil arborescent, 122.
----- stems, sections of, 62.
Ferry Bridge, Yorkshire, 44, 71.
-----------------------, buried forest at, 44.
Fifeshire, 617.
Filicites, 109.
Fisher, Rev. O., researches of, 196, 522, 557.
Fishes, characters of, 563.
------ tins of, 569, 576.
------ scales of, 566.
------ skeletons of, 572.
------ tails of, 574.
------ teeth of, 570, 582.
Fitton, Dr., works and researches of, 177, 230, 420, 529, 833.
Flabellina Baudouniana, 347.
Flamborough Head, 226.
Flint, casts of echinites in, 320.
----- formed from zoophytes, 243.
----- fossil wood in, 174.
----- polype in, 250.
----- sponges in, 222.
Flora of New Zealand, 210.
----- of Œningen, fossil, 200.
----- of the Carboniferous epoch, 209.
Florence Court, 278.
Florida, 365, 387.
Flowers, fossil, 197.
Flustra, 266.
Flying reptiles, 723.
Folkstone, 228, 402, 406, 426, 433, 458, 476, 487, 512, 858.
Foot-tracks of bipeds, 768.
----------- of Crustacea, 543, 749.
----------- of reptiles, 749.
Foraminifera deposit at Brighton, 368.
----------------------- Charing, 342, 363.
-------------------- in the United States, 364.
------------ fossil, 344.
------------ fossil remains of the soft parts of, 357, 372.
------------ in chalk and flint, 355.
------------ of the Carboniferous Formation, 365.
------------------- fens of Lincolnshire and Cambridgeshire, 367.
------------------- Oolite, Lias, &c., 364.
------------ recent, 339.
------------ tertiary, 366.
Foraminifera-rocks in Arabia, 362.
------------------ India, 362.
------------------ New Zealand, 366.
Forbes, Prof. E., works and researches of, 200, 299, 302, 304, 308,
380, 417, 419, 423, 530, 519, 557.
Foreign localities of fossil fishes, 641.
Forest marble, 28.
Forests, submarine, 70.
Forfarshire, 212, 525, 611.
Fossil animal remains, 43.
------ articulata, 503.
------ birds, 759, 763.
------ bones, 45.
------ botany, 51.
------ brachiopoda, 388.
------ cephalopoda, 447.
------ chelonians, 729.
------ diatomaceæ, 88, 93.
------ echinodermata, 311.
------ fishes, 562.
------ flowers, 197.
------ foraminifera, 336.
------ fresh-water plants, 195.
------ fruits from the Isle of Sheppey, 53, 186.
------ mammalia, 775.
------ microphytes, 88.
------ plants in the Devonian rocks
------ of Forfarshire and Ireland, 212.
------ polypifera, 251.
------ porifera, 219.
------ reptiles, 643.
------ resin, 52, 181.
------ shells, 381, 394, 413, 417, 421, 424.
------ sugar-loaves, 323.
------ vegetables, 51, 61, 86.
------ wood, examination of, 65.
------ zoology, 216.
Fossiliferous rocks, order of the, 21.
Fossils, definition of, 15, 37.
------- nature of, 37.
------- once thought to be _Lusus Naturæ_, 2.
Fowlstone, Mr., researches of, 702.
Franconia, 808, 820.
Frankfort, 202.
Fresh-water plants, fossil, 195.
---------- shells, fossil, 413, 421.
---------- turtles, fossil, 736.
Frogs, fossil, 740.
Fucoides Lamourouxii, 103.
Fucoids, fossil, 101.
Fuller’s-earth oolite, 28.
Fungia, 253, 256.
Fusulina cylindrica, 346.
Fusus contrarius, 418, 425.
G.
Gailenreuth, 808.
Galecynus Œningensis, 812.
Galerites albo-galerus, 322.
Galeritidæ, 322.
Galionella, 92, 96.
Ganoid fish, 568, 600.
Gardiner, Mr., researches of, 625.
Gasteropoda 378, 417.
Gavialis Dixoni, 677.
Geological distribution of bivalve and univalve mollusca, 436.
-------------------------- Cephalopoda, 492.
-------------------------- Crinoidea, 309.
-------------------------- Crustacea, 542.
-------------------------- Echinodermata, 330.
-------------------------- Fishes, 632.
-------------------------- Foraminifera, 369.
-------------------------- Sauroid-batrachians, 748.
-------------------------- Zoophytes, 273.
Geological Excursions. _See Excursions._
Geology, meaning of term, 1.
Geoteuthis, 463.
Geysers of Iceland, 40.
Gibbes, Dr. R. W., on fossil mosasaurus, 707.
---------------------------- squalidæ, 593.
Gibraltar, 765, 782, 808.
Gigantic crustaceans, fossil, 524.
-------- deer of Ireland, fossil, 783.
-------- sloths, fossil, 798.
Giraffe, fossil, 784.
Glammis, Forfarshire, 611.
Glaris, Switzerland, 730.
Glasgow, 746.
Globigerina cretacea, 342, 350.
Glossopteris Phillipsii, 116.
Glyphea rostrata, 519.
Glyptodon clavipes, 799.
Goldfuss, Dr., and Von Meyer, on the Archegosaurus, 746.
Goldsworth Hill, Surrey, 597.
Goniastea, 301.
Goniaster Hunteri, 305.
--------- Mantelli, 306.
Goniatites Listen, 482.
---------- striatus, 482.
Goniopholis crassidens, 658, 677.
Gorgonia, 253, 265.
Grantia, 221.
Graptolites Ludensis, 255.
----------- Murchisoni, 255.
Graptolitidæ, 254.
Grauwacke series, 32.
Gravesend, Kent, 305, 317, 355, 708, 710, 843.
Grays, Essex, 815.
Great Oolite, 28.
Greenland, 632.
Greenock, Lord, researches of, 622.
Grignon, France, 418, 425.
Grinsell, Salop, 712, 753.
Gristhorpe Bay, Yorkshire, 526.
Grooby, 903.
Gryphæa incurva, 397.
-------- sinuata, 398.
-------- virgula, 398.
Gryphites, 396.
Gymnosperms, 60.
Gyrodus Murchisoni, 609.
Gyrogonites, 195.
H.
Hackney, 674.
Halichondria, 221.
Halonia regularis, 144.
Hamites cylindraceus, 486.
Hammers, 832.
Hampton Court, polished Devonian marbles in pavements at, 476.
Hamsey, Sussex, 401, 408, 428, 459, 470, 476, 484, 485, 486, 487, 588,
621.
Hamster fossil, 803.
Hanwell, 395, 837, 859.
Hare, fossil, 809.
Harkness, Prof., researches of, 750, 772.
Harlam, Dr., on the Zeuglodon, 780.
Harris, Mr. W., researches of, 363, 579.
Hartwell, Bucks, 408, 428, 520, 557, 863.
Hartz, 808.
Hastings, Marchioness of, researches of, 676, 791.
Hastings, Sussex, 164, 180, 417, 773.
Havre, 680.
Hawkins, Mr. T., researches of, 48, 663.
Hawkshaw, Mr., on fossil foot-prints, 750.
------------------------ trees, 127.
Hayward’s Heath, 850.
Headley, Surrey, 395.
Headon Hill, Isle of Wight, 421, 423, 424, 847.
Heathfield, Sussex, 180.
Helianthoida, 254.
Hemerobioides giganteus, 553.
Hemicidaris crenularis, 311.
----------- intermedia, 316, 319.
Hemipristis serra, 591, 593.
Hempstead Cliff, 628.
Henslow’s, Prof., works referred to, 54.
Hermit-crab, fossil, 515.
Herne Bay, 791, 816, 843.
Herpetichnus, 753.
Hessburg, Saxony, 752.
Highgate Hill, 181, 367, 405, 463.
High Tor, Matlock, 875.
Highworth, Wilts, 397, 412.
Hildesheim, Saxony, 607.
Himalayas, 482.
Hippopotamus, fossil, 795.
Hippurites, 393.
Hitchcock, Prof., on Ornithoidichnites, 769.
Hoer, Scania, 122.
Hohen-Warte, Osterwald, 74.
-----------, brown-coal of, 74.
Holaster, 330.
Holectypus inflatus, 324.
Holloway, 882.
Holmes, Mr., researches of, 702.
Holoptychius, 618.
Holothuriadæ, 280.
Homalonotus delphinocephalus, 536.
Homœosolen ramulosus, 268, 271.
Honfleur, 680.
Hooker, Dr. J., on Arctic Diatomaceæ, 89.
-------------- on Lepidodendron, 139.
Hordwell, Hants, 405, 528, 595, 597, 675, 731, 738.
Horley, 850.
Horn of Iguanodon, 661.
Horse, fossil, 797.
Horsham, Sussex, 417, 774.
Howitt, Mrs., stanzas by, 496.
Hudson River, mixture of fluviatile and marine species in the, 100.
Human bones, fossil, 775, 815.
Hunterian Museum, fossils in the, 799, 801.
Hurstpierpoint, 851.
Hutton, Somerset, 811, 866.
Hyæna, fossil, 793, 808, 811.
Hybodus medius, 591.
------- raricostatus, 591.
------- subcarinatus, 578, 580.
Hydra, common fresh-water, 252, 253.
Hydroida, 254.
Hylæosaurus Owenii, 658, 688.
Hymenocaris, 526.
Hyopotamus, 791.
Hypanthocrinus, 297.
Hypogene rocks, 34.
Hypsodon Lewesiensis, 630.
Hyracotherium, 791.
Hythe, Kent, 182, 683.
I.
Iceland, 72.
-------, lignite in, 72.
Ichnolites of Crustacea, 543, 749.
------------- reptiles, 749.
----------, tridactylous, 768.
Ichthyodorulites, 576.
Ichthyolites, 562.
Ichthyopatolites, 632.
Ichthyosaurus, 662.
Idmonea Comptoniana, 268, 272.
------- cretacea, 268, 271.
------- Dixoniana, 268, 271.
Iguana, teeth of, 648.
Iguanodon Mantelli, 661, 691.
Illænus perovalis, 533.
Ilminster, 549, 560, 617, 669, 680.
Imprints of acalephs or jelly-fish on stone, 280, 772.
----------- feet of bird-like bipeds, 768.
----------- fin-markings, 632.
----------- leaves, 201.
----------- rain-drops on stone, 751, 771.
Incrustation, 38.
Incrusting springs at Matlock, 872.
India, beds of foraminifera in, 362.
Indiana, 365.
Inferior Oolite, 28.
Inoceramus concentricus, 402.
---------- Cuvieri, 401.
---------- shell perforated by Clionites, 403.
---------- sulcatus, 402.
Insectiferous Purbeck limestone, 556.
Insectivora, fossil, 812.
Insects, fossil, 547.
Instructions for collecting specimens, 831.
---------------- the microscopical examination of chalk, &c. 371.
Internal structure of sigillaria, 130.
Investigating fossil remains of plants, instructions for, 54, 61.
Ireland, 70, 94, 212, 321, 427, 430.
-------, fossil microphytes from, 94.
-------, peat-bogs of, 70.
Irish deer, fossil gigantic, 783.
Ischyodus, 590.
Isle of France, 763.
------- Man, 783.
------- Portland, 70, 156, 169,230, 397, 412.
---------------- petrified forest in the, 70.
------- Purbeck, 417, 422, 604, 736.
------- Sheppey, 175, 186, 193, 202, 307, 470, 511, 515, 591, 597, 674,
676, 731, 738, 767, 838, 840.
------- Wight, _passim_.
Isoletus, 537.
Isopoda, 521.
Issoire, 765.
J.
Jäger, Dr., researches of, 742, 805, 815.
Japan, 555.
Jardine, Sir W., researches of, 752, 753.
Jarrow, 139, 144.
Jaw of Iguanodon, 693.
Jeffery, Mr., on silicification, 38.
Jelly-fishes, 280, 772.
Jet, 72.
Johnston, Dr. G., on the porifera, 219.
Juglans nux-taurinensis, 198.
Jurassic formation, 27.
K.
Kakaunui, New Zealand, 348.
Kangaroo, fossil, 803.
Kelæno furiosa, 447.
Kendal, Westmoreland, 524.
Kent’s Cave, 810, 813, 816.
Kentucky, 298, 794.
Kimmeridge clay, 27.
Kington, Radnorshire, 524.
Kirkdale, Yorkshire, 764, 783, 802, 809.
Kirton, near Glasgow, 524.
Klein, Balthazar, on coal, 76.
Knorria taxina, 144.
Königsberg, Prussia, 182.
Köstritz, 813.
Kropp. Carniola, 809.
Kyson, Suffolk, 739, 791, 805, 812, 813, 815.
L.
Labyrinthodon Jægeri, 742, 753.
------------- leptognathus, 753.
------------- foot-prints of, 753.
------------- pachygnathus, 753.
------------- scutulatus, 743.
Labyrinthodontoid reptiles, the geological distribution of, 748.
Labyrinthodonts, 741.
Lacertia, 646, 705.
Lahn Valley, 765.
Lake Huron, 476.
---- Macquarrie, Australia, 171.
Lamellibranchiata, 376.
Lamna crassidens, 594.
----- elegans, 594.
Land-tortoises, 727.
Langton Green, Kent, 527.
Lapland, 96.
-------, diatomaceous earth in, 96.
Lartet, M., researches of, 814.
Lathrobium, 558.
Lawford, 765.
Lea, Mr. I., researches of, 749.
Leach, Dr., researches of, 512.
Leamington, 742.
Leaves, fossil, from Stradella, 201.
------, investigation of fossil, 64.
Lebach, Saarbrück, 745.
Lebias cephalotes, 562, 628.
Leguminosites dimidiatus, 189.
------------- subquadrangularis,189.
Leiodon anceps, 709.
Length of Iguanodon, 702.
Lennel Braes, near Coldstream, 167.
Lepadidæ, 506, 508.
Leperditia, 526.
Lepidodendron, 137.
Lepidoid fishes, 600.
Lepidosteus, 616.
Lepidostrobus, the fruit of Lepidodendron, 140.
Lepidotus Fittoni, 606.
--------- Mantelli, 605.
--------- minor, 607.
Leptæna, 392.
Leptolepis, 617.
Lewes, Sussex, 174, 234, 243, 244, 245, 248, 267, 268, 286, 291, 299,
320, 323, 388, 390, 399, 401, 403, 431, 458, 471, 491, 513, 517, 567,
577, 579, 584, 589, 584, 596, 624, 626, 628, 734, 779.
Lias series, 28.
Libellula, fossil, 551.
Lignite, 71.
Liliaceæ, 194.
Lily-encrinite, 285, 292.
Lily-like animals, 280.
Limnadiadæ, 526.
Limnæus longiscatus, 410, 423.
Limulus rotundatus, 522.
------- trilobitoides, 523.
Lincolnshire, 367.
------------ buried forests in, 70.
------------ fens, diatomaceous deposits in the, 95.
-----------------, fossil foraminifera of the, 367.
Lindley and Hutton, on fossil remains of plants, 61.
Lindley, Dr., on the principles of botany, 58.
------------ on venation of leaves, 64.
Lingula, 393.
Linnæus on Trilobites, 533.
Liparus, 558.
Lister, Dr. Martin, on fossils, 3, 18.
Lithododendron sociale, 227, 264.
Lithodomus, 408.
Lithornis vulturinus, 767.
Lithostrotion columnare, 260.
Lituola nautiloidea, 347, 349.
Liverpool, 198.
Llampeter, 504.
Llandeilo or Bala series, 33.
Lloyd, Dr., researches of, 742.
Lobster-clays of Atherfield, 518.
Lobsters, fossil, 515.
Localities, British, of fossil cephalopods, 499.
------------------------------ crustaceans, 546.
------------------------------ fishes, 640.
------------------------------ mammalians, 818.
------------------------------ reptiles, 756.
------------------------------ vegetables, 213.
------------------------------ zoophytes, 278.
----------, foreign, of fossil fishes, 641.
Lodève, 178.
Logan, Mr. W. E., researches of, 81, 543, 749.
Lonchopteris Mantelli, 119.
Lonjumeau, France, 197.
Lonsdale, Mr. W., researches of, 270, 274, 352, 408, 528, 530.
Lophiodon, 789.
Loricula pulchella, 507.
Lower Greensand, 25.
----- jaw of reptiles, 651.
----- Silurian, or Cambrian series, 33.
Ludlow, 255, 639.
------ Bone-bed, 639.
------ series, 33.
Lund, Dr., researches of, 799, 808, 814.
Lunel-Viel, 765.
Lunulites radiatus, 227, 273.
Lycopodites, 143.
Lycopodium, or club-moss, 140.
Lyell, Sir C., works and researches of, 20, 206, 289, 375, 413, 528,
558, 747, 751, 805.
Lyme Regis, Dorset, 176, 293, 304, 464, 492, 512, 520, 549, 585, 591,
596, 603, 664, 669, 725.
Lymm, Cheshire, 750, 772.
M.
Macculloch on coal, peat, lignite, &c., 76.
MacEnery, the late Rev. J., researches of, 810.
Mackeson, Mr., researches of, 683.
Mackie, Mr. J. S., researches of, 858.
Macleay, Mr., on trilobites, 534, 540.
M’Coy, Prof. F., works and researches of, 252, 275, 321, 524, 532, 534,
576, 514.
Macropoma Mantelli, 620.
Macrura, 515.
Madrepora, 253, 264.
Maestricht, 265, 269,274, 346, 411, 515, 705, 730.
---------- chalk, 25.
Magnesian limestone series, 30.
--------- limestones of Matlock, 878.
Maidstone, Kent, 173, 180, 194, 268, 409, 433, 485, 507, 518, 683, 692.
Maine, United States, 76.
-----, lignite in the hogs of, 76.
Malcolmson, Mr., researches of in India, 529.
Mallotus villosus, 631.
Malta, 326, 512, 591, 812.
Malton, 149, 492.
Mammalia, fossil, 775.
-------- of Stonesfield, fossil, 805.
-------- teeth of, 793.
-------- Triassic, 805.
Manchester, 129.
Mansfeld, Saxony, 178, 602.
Mantell, Mr. Reginald, researches of, 240; 290, 369.
------- Mr. Walter, researches of, 95, 211, 273, 347, 348, 366, 702.
Mantellia cylindrica, 158.
--------- nidiformis, 157.
Marbles composed of fresh-water shells, 422.
March, Lincolnshire, 368.
Margate, Kent, 230.
Marine univalves, fossil, 424.
Markfield, 903.
Marlstone of the Lias, 29.
Marsupialia, fossil, 803.
Marsupites Milleri, 289, 299.
Maryland, U. S., 593.
Massachusetts, 769.
-------------, biped foot-tracks of, 769.
Masson Hill, 870, 873.
Mastodon elephantoides, 794.
-------- giganteus, 786.
Matlock, 870.
Mauritius, 763.
Medals of creation, fossils so called, 17.
Megalichthys, 617.
Megalosaurus Bucklandi, 686.
Megaphyton, 144, 145.
Megatherium, 798.
Meissen, 765.
Melania, 426.
Melanopsis, 416, 424.
Melbourne, Australia, 803.
Melville, Dr., researches of, 681, 763.
Memel, Prussia, 182.
Mendip Hills, 810.
Meridion vernale, Dr. Bailey on the, 93.
Merstham, 849.
Mesostylus Faujasii, 515.
Metamorphic rocks, 34.
Meyeria ornata, 519.
Micraster cor-anguinum, 328.
Microdon, 610.
Microphytes, fossil, 88, 337.
Microscopical examination, 65, 371, 639.
Microzoa, 338.
Middleton Moor, Derbyshire, 285, 894.
Millepora rhombifera, 264, 268.
Miller, Mr., works and researches of, 288, 331, 456, 864.
------ Mr. Hugh, works and researches of, 32, 612, 614, 618, 619.
Millstone-grit, 31.
Mimosites Browniana, 189.
Minerals, definition of, 15.
Miocene deposits, 24.
Mississippi, floating wood-rafts of the, 79.
Missouri, U. S., 365, 628, 708.
Mocha-stones, 103.
Modiola, 407.
Moira, Ireland, 237.
Mole, fossil, 812.
Mollusca, 374.
Molluskite, 358, 432.
Monheim, Franconia, 711.
Monkeys, fossil, 813.
Monocarya centralis, 257.
Monocotyledons, 59.
Monomyaria, 395.
Monoprion, 256.
Montagu, Capt. W., notice of bone-caves in Franconia, 820.
Monte Bolca, 197, 599.
Montmartre, 198, 521, 731, 766, 789, 804, 813.
Moore, Mr. C., researches of, 549, 657, 680.
Mornbach, 766.
Morris, Mr., works and researches of, 233. 238, 404, 508, 549.
Morton, Dr., researches of, 257, 344, 399, 586.
Mosasaurus gracilis, 709.
---------- Hoffmanni, 705.
---------- Maximiliani, 708.
Moss-agate, 103.
Mosses, fossil, 104.
Mostyn, Flintshire, 632.
Mount Lebanon, 599.
Mount Randen, Switzerland, 297.
Mount Sorel, 868, 900.
Mountain limestone, 31.
Mouse, fossil, 809.
Muggendorf, 783.
Münster-Appel, 745.
Münster, Count, researches of, 465, 550.
Murchison, Sir R. I., works and researches of, 33, 80, 256, 365, 504,
558, 559, 753, 812.
Murchisonia bilineata, 430.
Mussel-band in the coal-measures, 414.
Mycetophila, 558.
Myliobatis micropleurus, 598.
Mylodon robustus, 800.
Mytilus, 407.
N.
Natica plicistria, 428.
Nautilidæ, 469.
Nautilus Deslongchampsii, 470.
-------- elegans, 471.
-------- pompilius, 467.
-------- pseudo-elegans, 470.
-------- Saxbyi, 472.
Nave-encrinites, 294.
Navicula, 91.
Nemacanthus, 588.
Nereis, 504.
Nereites Cambrensis, 504.
Nerita, 507.
Neuber’s liquid glue, 46.
Neuroptera, fossil, 551.
Neuropteris acuminata, 115.
Newcastle, 138,531.
New Cross, 837, 849.
Newhaven, lignite at, 73.
--------, near Leith, 601.
--------, Sussex, 73, 175, 201, 425, 578
New Jersey, U. S., 520, 585, 628, 708.
New Red Sandstone series, 29.
New Zealand, 95, 172, 318, 390, 763, 812.
-----------, cidarites from, 318.
----------- fossil birds of, 763.
----------- fossil diatomaceæ in, 95.
----------- fossil foraminifera in, 366.
----------- the flora of, 210.
Niagara River, 259.
Nice, 765, 808.
Nicol’s method of microscopical examination of fossil plants, 65.
Nipadites cordiformis, 188.
--------- lanceolatus, 188.
Nodosaria, 347.
Nodules, method of opening, 49.
Nœggerathia, 181.
Nonionina Germanica, 350.
Normandy, 470.
Northampton, the late Marquis of, researches of, 350.
Northfleet, Kent, 317, 711.
Norway, 256, 538.
Norwich, 406.
Notidanus microdon, 594.
Notopocorystes Bechei, 514.
-------------- Broderipii, 513.
-------------- Stokesii, 513.
Nucleolites, 326.
Nucula, 406.
Nummulites lævigatus, 344.
Nymphæa arethusa, 196.
O.
Obolus, 392.
Ocellaria inclusa, 247.
Odontopteris Schlotheimii, 116.
Œningen, near Constance, 200, 559, 627, 731, 741, 765, 812.
-------, fossil fox of, 812.
------- fossil insects from, 559.
Offenbach, 739.
Offham, Sussex, 267.
Ogygia Buchii, 537.
Ohio. U.S., 259, 262, 278, 286, 365.
Old Red Sandstone series, 31, 618.
Onychoteuthis, 462.
Oolite formation, 27.
------ zoophytes of the, 275.
Ophidia, 646, 738.
Ophiura Egertoni, 305.
------- Prattii, 305.
------- serrata, 305.
Ophiuridæ, 303, 304.
Opossum, fossil, 804.
Orbicula, 392.
Orbitoides Mantelli, 346.
Oreston, near Plymouth, 810.
Organic remains, nature of, 37.
Ornithoidichnites, 768.
Ornitholites, 759, 763.
Orthacanthus, 581.
Orthis, 392.
Orthoceratidæ, 469, 474.
Orthoceras conicum, 475.
---------- giganteum, 474.
---------- gregarium, 475.
---------- laterale, 475.
---------- striatum, 475.
Osmeroides Lewesiensis, 627.
---------- Mantelli, 627.
Osmington, Dorset, 408, 412.
Ossicles of encrinites, 284.
-------- starfishes, 303.
Ossiferous caverns, 808.
Ostend. near Bacton, 812.
Osteology of birds, 760.
--------- fishes, 572.
--------- mammals, 776.
--------- reptiles, 651.
Osteolepis, 618.
Ostracoda, 526.
Ostrea carinata, 396.
------ deltoidea, 396.
------ plicata, 396.
------ semiplana, 396.
------ vesicularis, 396.
Otodus obliquus, 591, 594.
Otolithes, 574, 639, 778.
Ototara, New Zealand, 366.
Owen, Prof.,[822] classification of animals, 826.
[822] We have here refrained from making many references to the very
numerous passages in the text in which our great palæontologist’s
investigations and opinion, in almost every branch of vertebrate
and invertebrate zoology, have been freely and of necessity quoted
by the Author and Editor,--always, however with due and grateful
acknowledgment.
------------------------------- reptiles, 646.
----------- on the archegosaurus, 746.
------------------ belemnite, 456.
------------------ brachiopoda,393.
------------------ dendrerpeton, 748.
------------------ dinosauria, 684.
------------------ labyrinthodonts, 742.
------------------ teeth of reptiles, 646.
------------------ zeuglodon, 781.
----------- work on British fossil mammals and birds referred to, 776,
_et passim_.
------------------ odontography, 564, 570, _et passim_.
------------------ the mylodon, 801.
Oxford clay, 27.
----------- fossil wood in the, 172.
Oyster-shells, fossil, 395.
P.
Pachycormus, 617.
Pachydermata, fossil, 785.
Pachypteris lanceolata, 112.
Paddle of ichthyosaur, 668.
--------- plesiosaur, 668.
Paisley, 525.
Palæochinidæ, 322.
Palæoniscus, 601.
Palæontology, meaning of the term, 2.
Palæophis toliapicus, 738.
--------- typhæus, 738.
Palæosaurus, 713.
Palæospalax, 812.
Palæotherium magnum, 789.
Palæoxylon, 167.
Palæozoic cidaritidæ, 321.
--------- rocks, 30.
--------- zoophytes, 275.
Palapteryx, 764.
Palermo, 808.
Paleryx, 738.
Palliobranchiata or Brachiopoda, 376.
Palmacites, 183.
Palm-fruits, fossil, 186.
Palm-leaves, fossil, 185.
Paloplotherium, 791.
Paludina fluviorum, 418, 421.
Pampas, South America, 798.
Pandanus, fossil fruit of, 192.
Panorpa Liassica, 553.
Paper-nautilus, 450, 465.
Pappenheim, 520, 521.
Parabatrachus Colei, 746.
Paradoxides Bohemicus, 538.
Paramoudra, 236.
Paris. _See Montmartre._
Parish, Sir Woodbine, works and researches of, 798, 799.
Parkinson, Mr., his work and researches, 77, 292, _et passim_. _See
Pict. Atlas._
Pearce, Mr. C., researches of, 288, 456, 669.
Pear-encrinite, 287.
Peat, 70.
Pecopteris lonchitica, 118.
---------- Murrayana, 118.
---------- Sillimani, 110.
Pecten Beaveri, 400.
------ Jacobæus, 400.
------ quinquecostatus, 400.
------ opercularis, 385.
Pectunculus, 405.
Pedicellariæ, 313.
Pentacrinus caput-medusæ, 282.
----------- Hiemeri, 293.
Pentamerus, 391.
Penthetria, 558.
Pentremites pyriformis, 286, 297.
Permian deposits, 30.
Perna, 402.
Petalopora pulchella, 224, 270.
Petersburgh, Virginia, 97.
------------------, diatomaceous earth at, 97.
Petricola Patagonica, 377.
Petrifactions, nature of, 37.
Petrified forests of conifers, 169.
--------- "horns," 394.
--------- "mushrooms," 242.
--------- "rams'-horns," 260, 862.
--------- "salt-cellars," 861.
--------- trees in Egypt, 203.
Petrophiloides Richardsoni, 188.
Peuce, 168.
Pevensey, 519.
Phacops caudatus, 538.
Phanerogamia, 59.
Phascolotherium Bucklandi, 806.
Phlebopteris Phillipsii, 120.
------------ propinqua, 120.
Phillips, Prof., works and researches of, 44, 321, 365, 420, 427, 807.
Pholadomya, 408.
Pholas priscus, 408, 507.
Phryganea, fossil larvæ of, 559.
Physa in the Purbeck beds, 423.
Pickering, Yorkshire, 307.
Pictou, Nova Scotia, 109.
Pictorial Atlas, referred to, 9, 187, 228, 257, 263, 285, 317, 404, _et
passim_.
Pinites Fittoni, 177.
Pinna, 406.
Pinus, 177.
Placodus, 610.
Placoid fish, 568, 582.
Plagiostoma giganteum, 400.
Planorbis, 423.
Plants, fossil, 51.
Platycrinus, 287.
Platysomus, 610.
Pleistocene deposits, 23.
Pleodont lizards, 648.
Plesiosaurus, 662. 671.
Pleurodont reptiles, 648.
Pleurotoma, 425.
Pleurotomaria flammigera, 427.
Plicatula inflata, 400.
Plieninger, M., researches of, 805.
Pliocene deposits, 24.
Pliosaurus, 673.
Plumstead, Kent, 395, 406.
Plutonic rocks, 34.
Podocarya, 192.
Podosphenia, 92.
Podozamites Mantelli, 154.
Pœcilopleuron Bucklandi, 679.
Polierschiefer of Bilin, 96.
Polperro, Cornwall, 238.
Polycotyledons, 60.
Polyparium, 252.
Polype in flint, 250.
Polypidom, 252.
Polypifera, 251, 280.
Polypothecia dichotoma, 231.
Polyptychodon continuus, 683.
------------- interruptus, 683.
Polyzoa, 253.
Pondicherry, 485.
Poole, Dorset, 560.
Populus gæeca, 201.
Porcupine, fossil, 803.
Porifera, 219.
Portishead, 864.
Portland. _See_ Isle of Portland.
-------- oolite, 27.
Post-pliocene deposits, 23.
Potamides, 425.
Potamogeton, fossil, 106, 201.
Poteriocrinus, 287.
Potsville, U.S., 645.
Potter, Mr., researches of, 579.
Pounceford, Sussex, 105.
Prestwich, Mr., researches of, 523, 528, 542
Preston, Sussex, 227, 305.
Primrose Hill, 767.
Pristis, 597.
Productus, 392.
Protozoa, 219.
Psammodus, 587.
Psarolites, 123.
Pseudomorphic crystals, 42.
Pterichthys cornutus, 612.
Pterodactylus compressirostris, 726.
------------- crassirostris, 724.
------------- Cuvieri, 726.
------------- macronyx, 726.
Pterophylluni comptum, 152.
Pteropoda, 378, 417.
Pterosauria, 646, 723.
Pterygotus, 525.
Ptychoceras Emericianum, 486.
Ptychodus gibberulus, 578.
--------- polygurus, 594.
--------- spectabilis, 578, 585.
Pulley-stones, 285.
Purbeck. See Isle of Purbeck.
------- marble, 422, 435.
------- series, 26.
Purfleet, 317, 843.
Pustulopora pustulosa, 268, 270.
Puy-de-Dome, 765.
Puy en Velais, 186.
Puzzuoli, 408.
Pycnodus, 607.
Pyrenees, 393, 432.
Pyrites, 893.
Pyritous fossil fruits, 53.
Pyxidiculum, 91.
Q.
Quadrumana, fossil, 813.
Quedlingbourg, 765.
Queenborough, 838.
R.
Radiata, 280.
Radipole, Dorset, 408, 412.
Radoboj, Croatia, 559.
Railway sections, 837, 849, 859.
Rain-prints on stone, 751, 771.
Raphiosaurus subulidens, 711.
Rastrites, 256.
Ratisbon, 591.
Rays, fossil, 597.
Reade, Rev. J. B., researches of, 241, 250.
Reading, Berkshire, 395.
Recent shell-rock, 384, 386.
Redland, near Bristol, 713.
Regent’s-park, London, 194, 411.
Regnosaurus Northamptoni, 705.
Remains, fossil animal, 43.
Reptilia, 643.
Reptiles, Ichnolites of, 749.
Resins, fossil, 52, 181.
Retepora laxa, 269.
Retrospect of fossil Botany, 206.
-------------------- zoology, 822.
Rhine, brown-coal of the, 72.
-----, tripoli of the, 90.
Rhinoceros, fossil, 796.
Rhizopoda, 338.
Rhodocrinus, 287, 297.
Rhynchonella plicatilis, 388, 391.
------------ subplicata, 388, 391.
Rhynchosaurus articeps, 712.
-------------, foot-prints of, 753.
Richardson, Mr. W., researches of, 791, 843.
Richmond, Virginia, 97.
------------------, diatomaceous earth at, 97.
Ridgway Hill, Dorset, 522. 557.
Riley, Dr., researches of, 713.
Ringinella, 426.
Ringmer, Sussex, 406, 453, 458, 487, 490, 512, 519.
River-tortoises, 727.
Rjeff on the Volga, 608.
Roane Hill, Tyrone, 601.
Rochester, 508.
Rocks and strata, 19.
Rodents, fossil, 802.
Rodriquez Island, 763.
Roof of the coal, 82.
Rosalina, 342, 351, 356, 358, 359.
Rostellaria, 426.
Rotalia, 351.
Rottingdean, 852, 856, 858.
Rouen, 368, 471, 491.
Rule, Mr., researches of, 763.
Ruminants, fossil, 782.
Runcorn, Cheshire, 750, 772.
Ruppersdorf, Bohemia, 581.
Russia, 365, 392, 524, 538, 608, 619.
Ryde, Isle of Wight, 816, 847.
S.
Saarbrück, Lorraine, 601.
Sabella, 385.
Sacrum of reptiles, 655.
Sahara Desert, 170.
Salamander, fossil, 741.
Salamandroïdes, 742.
Salenia, 318.
Salter, Mr., researches of, 524, 526, 534, 749.
Sandgate, Kent, 409, 507.
Sandown Bay, Isle of Wight, 155, 164, 529.
Sansan, near Audi, 814.
Santa Fiora, diatomaceous earth at, 96.
Sardinia, 765.
Saull, Mr. W. D., researches of, 795.
Sauria, 646.
Saurocephalus lanciformis, 629.
------------- striatus, 629.
Saurodon Leanus, 629.
Sauroid fishes, 615.
Sauroidei, 617.
Sauroidei-dipterini, 618.
Savone, 790.
Saw-fish, fossil, 597.
Scales of fishes, 566.
Scalpellum maximum, 507.
Scaphites æqualis, 488.
Scarborough, 73, 113, 114, 116, 118, 152, 154, 168, 519.
Scat-craig, Elgin, 618.
Schaerbeek, Belgium, 191.
Scorpion, fossil, 550.
Scouler, Dr., researches of, 525.
Screw-pines, 192.
Screw-stones, 285.
Scrope, Mr. P., on fossil phryganeæ, 560.
Scutes of reptiles, 657.
Scyphia foraminosa, 227.
------- intermedia, 227.
------- ramosa, 227.
Sea anemones, 254.
--- eggs, 312.
--- slugs, 280.
--- urchins, 280, 312.
Seafield, Isle of Wight, 791.
Seal, fossil, 812.
Secondary rocks, 25.
Selbourne, Hants, 396.
Sepia, fossil, 447.
Septarium with shells, 383.
Serpents, 738.
Serpula, 385, 505.
Serres, Marcel de, researches of, 557.
Sertularia, 253.
Shalcombe, Isle of Wight, 421.
Shanklin, or Lower Greensand, 25.
Sharks, fossil teeth of, 582.
------ vertebræ of, 596.
Sharp Mountain, Pennsylvania, 749.
Shepherd’s crowns, 327.
Sheppey, _See_ Isle of Sheppey.
Shotover, Oxon, 680.
Shrewley Common, Warwickshire. 753.
Shrewsbury, 531, 712.
Shrimps, fossil, 520.
Sicily, 390.
Siderastræa Websteri, 264.
Siderolina, 346.
Sigillariæ and Stigmariæ, 125.
Sigillaria Defrancii, 128.
---------- elegans, 130.
---------- Saullii, 129.
Silesia, 185.
Silicification, 40.
Silurian system, 32.
Sind, 362.
Siphonia lobata, 231.
-------- Morrisiana, 224, 233.
-------- pyriformis, 231.
Siwalik Hills, 185, 278, 674, 731, 766, 782, 784, 786, 797, 814.
Skeleton of fishes, 572.
Skin of Ichthyosaur, 670.
Sloths, fossil gigantic, .798.
Smee, Mr., on fossilization of bones, 44.
Smerdis minutus, 625.
Smith, Dr. William, on fossils and strata, 18.
-----, Mr. Toulmin, on the ventriculidæ, 226, 249, 268.
Snakes, fossil eggs of, 739.
Snibstone, Leicestershire, 149, 902.
Solarium ornatum, 427.
Solenhofen, 447, 492, 511, 520, 523, 550, 551, 617, 621, 724.
----------, fossil insects from, 551.
Soleure, 730.
South Africa, 536, 714.
------------, fossil reptiles from, 714.
South America, bone-caves of, 808.
-------------, fossil edentata of, 798.
--------------------- monkey of, 814.
-------------, Pampas of, 798.
Southbourn, Sussex, 232, 408, 433, 487, 858.
Southerham, Sussex, 401, 487.
South Joggins, Bay of Fundy, 128, 747.
South Petherwin, Cornwall, 474.
Spatangidæ, 326.
Spatangus planus, 330.
Sphærulites Mortoni, 393, 430.
Sphenophyllum erosum, 146, 148.
------------- Schlotheimi, 147, 148.
Sphenopteris elegans, 112.
------------ Mantelli, 113.
------------ nephrocarpa, 113.
Spicula of sponges, 234, 238.
Spiders, fossil, 550.
Spinax major, 580, 584.
Spines of Cidarites, 319.
Spiniferites palmatus, 241.
------------ ramosus, 239, 240.
------------ Reginaldi, 239, 241.
Spirifer trigonalis, 390.
Spirolina, 349.
Spirulirostra Bellardii, 463.
Spondylus spinosus, 399.
Sponges, characters of, 220.
-------, arrangement of recent, 221.
------- in chalk and flint, 222.
Spongilla, 221.
Spongites clavellatus, 224.
--------- flexuosus, 226, 213.
--------- labyrinthicus, 225, 243.
--------- ramosus, 223.
--------- Townsendi, 225.
Spynie, near Elgin, 720.
Squaloraia, 596.
Squirrel, fossil, 802.
St. Catherine’s, Isle of Wight, 233.
--------------- Mount. _See_ Rouen.
St. Cuthbert’s beads, 284.
St. Etienne, France, 127, 178.
St. Helen’s, near Liverpool, 136.
St. Peter’s Mount. _See_ Maestricht.
Staaren-stein, 123.
Stag-horn encrinite, 291.
Staithes, near Whitby, 307.
Stammerham, Sussex, 774.
Steganodictyum, 233.
Steinhaur, Rev. H., on Stigmaria, 134.
Stellaridæ, 280.
Stems of arborescent ferns, 122.
-------- encrinites, 284.
-------- pentacrinites, 284.
-------- plants, structure of, 55, 62.
Sigillariæ, 128.
Steneosaurus, 676.
Sternbergia, 168.
Sternum of ichthyosaur, 667.
---------- plesiosaur, 667, 672.
Steyning, Sussex, 459, 471.
Stigmaria ficoides, 133.
Stigmariæ, the roots of sigillaria and lepidodendron, 132, 139.
Stokes, Mr., researches of, 476, 540.
Stone-lily, 292.
Stone, Bucks, 557.
Stone perforated by lithodomi, 408.
Stonesfield, Oxon, 152, 168, 181, 553, 587, 686, 725, 730, 765, 805.
-----------, fossil mammalia of, 805.
----------- slate, 28.
Stonnis, 883, 896.
Storeton Hill, near Liverpool, 730, 751, 753, 772.
-------------, ichnolites at, 751, 772.
Stradella, near Pavia, 201.
Strata and rocks, 19.
------ composed of foraminifera, 352.
------, synopsis of British, 23.
Stratification of a coal-field, 80.
Strensham, Worcestershire, 106.
Streptospondylus, 680.
Strickland, Mr. H. E., researches of, 552, 639, 753, 763.
Stromatopora, 262.
Strombodes, 262.
Strophodus magnus, 587.
Structure of coniferæ, 57.
------------ vegetables, 55.
Studd Hill, 843.
Stutchbury, Mr., researches of, 265, 713.
Stuttgart, Würtemberg, 805.
Stylastritæ, 287.
Sub-Apennines, 503.
Sub-Himalayas. _See_ Siwalik Hills.
Submerged forests, 70.
Suchosaurus cultridens, 676.
Suggsville, U. S., 346.
Sulz-les-bains, near Strasburg, 117, 181.
Sunderland, 430.
Sundridge, Kent, 395.
Sussex marble, 422, 435.
Swabia, 775, 815.
Swanage, Purbeck, 196, 607, 658, 677.
------- crocodile, 677.
Swansea, 810.
Sweden, 256, 392, 538.
Swindon, 168, 412, 428, 862.
Swithland, 900.
Switzerland, 289.
Sydenham, 789, 849.
Synhedra, 92.
Synopsis of British strata, 23.
Syringopora ramulosa, 259, 262.
T.
Tæniopteris latifolia, 118.
Taggart, Mr., researches of, 772.
Tails of fishes, 574.
Taxites, 181.
Teeth of Fishes, 570, 582.
-------- Glyptodon, 799.
-------- Ichthyosaur, 665.
-------- Iguanodon, 693.
-------- Labyrinthodon, 743.
-------- Mammalia, 793.
-------- Plesiosaur, 665.
-------- Reptiles, 646.
-------- Sharks, fossil, 582.
Teleosaurus Cadomensis, 680.
----------- Chapmanni, 675, 679.
----------- priscus, 680.
Telerpeton Elginense, 720.
Temple Church, the pillars of, composed of fresh-water marble, 422, 435.
Temple of Jupiter Serapis, the columns of, perforated by Lithodomi, 408.
Terebratula carnea, 390.
----------- semiglobosa, 388.
----------- subrotunda, 388.
Teredo, 193, 410.
Tertiary coniferous wood, 175.
-------- foraminifera, 366.
-------- ornitholites, 765.
-------- rocks, 24.
-------- zoophytes, 274.
Tethea, 221.
Tettigonia spumaria, 558.
Tetrabranchiata, 449, 466.
Tetragonolepis, 604.
Textularia globulosa, 342, 352.
Thalictroides Parisiensis, 198.
------------- Websteri, 198.
Thames River, 386.
Thecodontosaurus, 713.
Thecodont reptiles, 648.
Thuites Kurrianus, 180.
Tilgate Forest, Sussex, 75, 113, 119, 159, 414, 417, 530, 578, 580,
592, 605, 608, 660, 677, 681, 687, 690, 704, 725, 734, 773, 768.
Tisbury, Wilts, 263, 413.
Toadstone of Derbyshire, 875, 878, 893.
Torbay, Devon, 259, 262, 764, 810, 816.
Torpedo. 598.
Tortoises, 726.
Touraine, 426.
Toxaster complanatus, 329.
Toxoceras Emericianum, 484.
Track-marks of bipeds, 768.
-------------- crustaceans, 543, 749.
-------------- fishes, 632.
-------------- reptiles, 749.
Tragos Farringdoniensis, 229.
------ peziza, 229.
Transition series, 32.
Trap of Crich Hill, 884, 891.
Travertine, or tufa, 40.
Trees, fossil, dicotyledonous, 203.
-------------, in the Coal-measures, 136.
--------------------- Purbeck series, 169.
--------------------- Wealden, 170.
-----, silicified, in Australia, 170.
--------------------- Egypt, 170, 203.
Tretosternon Bakewelli, 737.
Trevelyan, Mr., fossil upright stems in Northumberland noticed by, 128.
Trias series, 29.
Triassic mammalian teeth, 805.
Tridactylous imprints, 768, 772.
Trigonia clavellata, 397, 412.
-------- costata, 397, 412.
-------- gibbosa, 397, 412.
Trigonocarpum Nœggerathi, 149.
------------- olivæforme, 149.
Trilobites, 532.
----------, geological distribution of, 543.
Trinucleus Lloydii, 538.
Trionyx, 727.
Triplosporite, 142.
Trochites, 284.
Trochus ziziphinus, 385.
Trogontherium, 803.
Trowbridge, Wilts, 479.
Trunks and stems of fossil cycads, 156.
------ of sigillariæ with roots, 126.
--------- trees, investigation of, 62.
Tufa or travertine, 40, 872.
Tunbridge Wells, 415, 530.
Tunicata, 375.
Turban-echinites, 313.
Turbinolia Kœnigii, 257.
Turin, 198, 463.
Turner’s Falls, Massachusetts, 769.
Turrilites catenatus, 489.
---------- costatus, 489.
---------- tuberculatus, 491.
Turritella conoidea, 383.
Turtles, 726.
Tuscany, 803.
U.
Ulodendron, 144, 145.
Under-clays of the coal, 81.
Unio, 414.
United States, 256, 257, 364, 367, 399, 400.
Univalve mollusks, 378, 417.
Upper Silurian series, 33.
Upright trunks of sigillariæ, 125.
Ursus arctos, 811.
----- priscus, 812.
----- spelæus, 811.
V.
Vale of Wardour, 521, 552, 556.
Valley of the Derwent, 882.
Van Diemen’s Land, 170.
Vegetables, fossil, 51.
----------, organization of, 54.
Venation of leaves, 60, 64.
Venericardia, 405.
Ventnor, Isle of Wight, 230.
Ventriculites alcyonoides, 247.
------------- quadrangularis, 267.
------------- radiatus, 242, 244.
Venus’s fan, 265.
Verneuilina tricarinata, 342, 352.
Vertebræ of Fish, 574.
----------- Ichthyosaur, 666.
----------- Iguanodon, 698.
----------- Reptiles, 651.
----------- Serpents, 739.
Verticellipora anastomosans, 227, 229, 273.
Virginia, 97, 170.
--------, fossil microphytes from, 97.
Visé, Belgium, 459.
Volcanic rocks, 35.
Volkmannia, 146.
Voltzia, 180.
W.
Waihora Lake, New Zealand, diatomaceæ from, 95.
Wainlode Cliff, Gloucestershire, 553.
Wakebridge, 884.
Wakefield, Col., researches of, 763.
Walchia hypnoides, 178.
Waldenburg, Silesia, 112.
Walton, Essex, 817.
Wandsworth, 837.
Ward, Dr. O., researches of, 712.
Wareham, Dorset, 200.
Warminster, Wilts, 231, 318.
Water-rat, fossil, 809.
Warwick, 742.
Watchett, Somerset, 480.
Wealden coal, 73.
------- formation, 26.
-------, remains of birds in the, 768.
-------, tridactylous ichnolites in the, 773.
Webster, Prof., researches of, 22, 156, 202.
Wellington Valley, Australia, 803.
Wenlock series, 33.
--------------, corals in the, 258, 261.
-------, graptolites in the, 255.
Westbury-on-Avon, 526, 588.
Western Lines, Isle of Wight, 230.
Westphalia, 622, 621.
Westwood, Mr. J. O., researches of, 549.
Wetherell, Mr. N. T., researches of, 508, 708.
Wetherellia variabilis, 188.
Weymouth, 397.
Whales, fossil, 777.
Whitby, 73, 106, 112, 477, 675,682.
Whitecliff Bay, Isle of Wight, 185.
Whittingham, Norfolk, 236.
Whitwick, 902.
Wiesbaden, 766.
Wiesnau, 766.
Williams, Rev. D., researches of, 811.
--------, Rev. W., researches of, 763.
Williamson, Prof., researches of, 155, 363, 367, 568, 620.
Willingdon, Sussex, 156, 173.
Witham’s method of microscopical examination of fossil plants, 65.
Wood, examination of fossil, 65.
----, fossil coniferous, 167.
---- perforated by pholades, 409.
------------------ teredines, 193, 411.
Woodhouse, 901.
Woodward., Mr. S. P., notes by, 236, 317, 379, 425, 426, 447, 462, 463,
479.
--------, Manual of Molluscs by, 381,449, 483.
Woolwich, Kent, 395, 425.
Worthing, Sussex, 235, 431.
Würtemberg, 308, 463, 742, 805.
Wyman, Prof. J., on dendrerpeton, 747.
---------------, on Lepidosteus, 616
X.
Xanthidium, 91.
Xiphodon, 790.
Y.
Yorkshire, 226, 227, 268, 305, 427, 465, 477, 519, 595, 608.
--------- oolite, 27.
Z.
Zamiæ, 150.
Zamites crassus, 155.
------- Mantelli, 154.
------- ovatus, 155.
------- pectinatus, 152.
-------Sussexiensis, 156.
Zanthopsis Leachii, 512.
---------- tuberculatus, 512.
Zeuglodon cetoides, 779.
--------- squalodon, 781.
Zoology, fossil, 216.
Zoophytes, 218.
---------, distribution of fossil, 273.
Zulinosprionites latus, 189.
THE END.
R. CLAY, PRINTER, BREAD STREET HILL.
Transcriber Note
Some standardization of word usage and formatting was made; but some
of the original variant spellings retained (ex., M'Coy and McCoy).
Italicizing of species, publications, authors, etc. was preserved.
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