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Title: The Coal Measures Amphibia of North America
Author: Moodie, Roy Lee
Language: English
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Transcriber Note


Text emphasis denoted as _Italics_ and =Bold=. Whole and fractional
parts of numbers as 123-4/5.



THE COAL MEASURES AMPHIBIA

OF

NORTH AMERICA


By

ROY LEE MOODIE

_Associate in Anatomy, University of Illinois, Chicago_


[Illustration]


Published by the Carnegie Institution of Washington

WASHINGTON, 1916


CARNEGIE INSTITUTION OF WASHINGTON

Publication No. 238


  PRESS OF J. B. LIPPINCOTT COMPANY
  PHILADELPHIA



PREFATORY NOTE.


The Carnegie Institution of Washington has already published several
monographs upon paleobiological subjects, written by its research
associates, Hay, Wieland, and Case. Each author has dealt with the
subject-matter of his particular field, but each has brought to bear upon
his work common factors which have placed his labors upon a broader basis
than the mere morphological descriptions of fossil forms of life. Case
has published four monographs upon the morphology and taxonomy of the
Permo-Carboniferous vertebrates of North America, and has followed these
by a fifth, in which all the known factors bearing upon the development of
the life were assembled in an effort to discuss the paleogeography of the
period. In his conception paleogeography is a very broad term, involving
not only a study of the distribution of land, water, and life in any one
interval of time, but a consideration of all the factors in the extremely
complex inter-relations of organic and inorganic matter and causes which
influence the development of each part.

Geologists and paleobiologists have alike suffered in their interpretation
of past conditions, because of their lack of knowledge of the work
done by others. Stratigraphy may not be interpreted from the preserved
fossils without a knowledge of biological laws, and the formations of the
earth may not safely be rearranged to account for the present or past
distribution of life without a knowledge of geological processes.

It is obvious that such work is beyond the possibilities of any one man;
it is rather the work of a group of men, each broadly trained and each
master of his own field and able to contribute to and criticize the
work of his fellows. Nowhere could close cooperation of this kind be
better accomplished than under a system such as the Carnegie Institution
of Washington has developed, whereby the research associates of the
Institution and others of its staff may call in the assistance of men in
related fields. Already the value of this procedure is apparent in the
results accomplished by cooperation.

The following monograph, by Dr. Roy L. Moodie, adds an important link
to the series of paleobiological publications of the Institution and is
closely connected with the work already done upon the Permo-Carboniferous
vertebrates, since it supplies a description of the life of the period
immediately preceding. It is hoped that the volume will contribute
in no small measure to an understanding of the broader problems of
paleogeography and the recognition of the mutual problems of the
paleobiologists and the geologists.

                                                                E. C. Case.

  University of Michigan, _March 15, 1916_.



PREFACE.


The question of the origin of land vertebrates, which has appealed so
strongly to students of fossil Amphibia, is by no means solved from the
material furnished by the Coal Measures of North America. The Amphibia
are, however, well known from several localities in the Coal Measures of
this continent, where skeletons have been recovered which are sufficiently
well preserved to afford a fair knowledge of their anatomy. The specimens
rescued from the dumps of the old mines are regrettably few in comparison
with the number that must have been burned as fuel, or carried down the
slopes as silt. Yet scanty as is the material thus collected, it is of
great importance, because it represents such an early period in the
recorded history of the air-breathing vertebrates.

The amphibian fauna in the Coal Measures of North America is represented
by several hundred individual specimens, preserved in various museums. All
of the collections have been available in the preparation of this memoir,
with the exception of those species from Nova Scotia which are preserved
in the Peter Redpath Museum of McGill University and in the British
Museum of Natural History. The European material, which has been used in
comparisons with the American forms, has been studied chiefly from the
literature, although there have been available a series of specimens of
_Branchiosaurus amblystomus_ Credner, from Saxony, presented by the late
Professor Credner, and a single specimen of _Archegosaurus_ from Dr. von
Huene, of Tübingen.

The collection which has been of the greatest value is that at the
American Museum of Natural History, chiefly assembled by Dr. J. S.
Newberry from the dumps of the coal mines at Linton, Ohio, while he was
in charge of the Ohio Geological Survey (1869-1884). This collection, a
part of which is at Columbia University, furnished Cope with the most of
his type material for the "Synopsis of the Extinct Batrachia from the Coal
Measures" (123).[A] This entire collection, including all of Professor
Cope's types and representing many new and hitherto undescribed forms,
was generously placed at the writer's disposal for a period of five years
through the kindness of Dr. Bashford Dean and Dr. Louis Hussakof. Dr.
Hussakof made a trip through the Linton region and his description of the
place occupied by the "Old Diamond Mine" is given on page 16.

[Footnote A: The numbers in parentheses refer to the bibliography at the
end of this volume.]

An interesting collection of air-breathing vertebrates from the Coal
Measures, representing 19 species, is in the U. S. National Museum (464).
This is chiefly the collection of Mr. R. D. Lacoe and includes specimens
from Mazon Creek, Illinois, from Kansas, and from Linton, Ohio. It is
especially important in that it contains the skeleton (plate 20, fig. 3)
of _the oldest known reptile_, _Eosaurus copei_ Williston (Jour. Geol.,
XVI, 295). It contains also, besides many of Cope's types, new forms which
have been described by the writer (464, 470, 471, 472, 473, 474, 478,
479). Dr. Stuart Weller first secured the use of this collection for me,
and its continued use has been granted by Dr. C. D. Walcott. Mr. Charles
Gilmore has called my attention to several interesting specimens and has
kindly loaned them for description.

A small but interesting collection of Mazon Creek Amphibia is that of the
Peabody Museum of Yale University. Through the courtesy of the officers
of this museum the writer was permitted to study these specimens and
was given a grant for their illustration. The results of that study
are contained in a previous paper (478) and in the present memoir. Dr.
Schuchert has offered suggestions as to the environmental conditions of
the ancient Amphibia.

A few specimens of Coal Measures Amphibia are at the Walker Museum,
University of Chicago. This collection includes the type of _Micrerpeton
caudatum_ Moodie, the first branchiosaur discovered in the western
hemisphere, and a few specimens from Linton, Ohio.

A single specimen of _Amphibamus grandiceps_ Cope, very beautifully
preserved, is in the possession of Mr. L. E. Daniels, of Rolling Prairie,
Indiana. This specimen has been studied and described by Hay (316) and by
the writer (462, 469, 478).

The works of Cope and Dawson, published between 1860 and 1897, on the
Amphibia from the Coal Measures, have been indispensable in the present
study. It has been necessary to rely on the published descriptions and
photographs of the interesting fauna from Nova Scotia, since it has not
been possible for me to visit and examine the types preserved in the Peter
Redpath Museum of McGill University and in the British Museum of Natural
History. It has been possible to check Dawson's work, to a certain extent,
by a study of a series of excellent photographs of the types of Coal
Measures Amphibia collected by Dawson and Lyell and described by Dawson
and Owen. The descriptions of these authors have been drawn on for the
discussion of the Canadian forms.

The descriptions given below have been made full and complete in the
belief that in this way our knowledge of these interesting vertebrates
may be advanced. Many of the species have been described elsewhere in
scattered papers by various authors. These descriptions have been revised
and verified and are collected here in monographic form. The work is a
morphologic and taxonomic revision of the Amphibia from the Coal Measures
of North America. Especial attention has been paid to the factors which
have been most active in the evolution of the group, so far as these
factors may be interpreted. It is the author's hope that this review may
open up the field for many more workers, since we are just beginning to
learn about the evolution of this group of vertebrates.

The trustees of the Elizabeth Thompson Science Fund allotted a grant for
the present investigation. This aid has enabled the writer to present his
work in much better form than would have been possible otherwise. Dr.
S. W. Williston has offered many suggestions and criticisms which have
been gratefully adopted. It is with the greatest sense of pleasure that
the author dedicates this memoir to his teacher and friend. After the
manuscript was completed the author enjoyed a visit from Mr. D. M. S.
Watson, of King's College, London, whose knowledge of the European and
African forms enabled him to offer several very valuable suggestions.

It is fitting also to express my indebtedness to the Carnegie Institution
of Washington for the privilege of publishing my work in the series of
monographs contributed by Dr. E. C. Case, dealing with the anatomy and
relationships of the early land vertebrates of North America.

  Roy Lee Moodie.



CONTENTS.


                                                                      PAGE.

  Prefatory Note                                                       iii

  Preface                                                               vi

  List of Illustrations                                             viii-x

  CHAP.

      I. The Problem of the Amphibia from the Coal Measures            3-5

     II. History of the Discovery of Amphibia in the Coal Measures     6-8

    III. Stratigraphic and Geographic Distribution of Amphibia in
           the Coal Measures of North America                         9-22

     IV. The Morphology of the Coal Measures Amphibia                23-36

      V. The Amphibia of the Devonian and Mississippian of North
           America                                                   37-38

     VI. A History of the Classification of the Amphibia, With
           Especial Reference to the Species from the Coal Measures  39-45

    VII. Classification of Amphibia Adopted in This Work, and a List
           of the Coal Measures Amphibia from North America          46-48

   VIII. Definition of the Class Amphibia, the Subclass Euamphibia,
           and the Order Branchiosauria                              49-50

     IX. The American Coal Measures Branchiosauridæ                  51-66

      X. The Order Caudata                                           67-71

     XI. The Order Salientia                                         72-74

    XII. The Subclass Lepospondylia, the Order Microsauria, and
           the Group Aistopoda                                       75-77

   XIII. The Microsaurian Family Hylonomidæ, from the Coal Measures
           of Nova Scotia                                            78-84

    XIV. The Microsaurian Family Tuditanidæ, from the Coal Measures
           of Ohio and Pennsylvania                                 85-111

     XV. The Microsaurian Family Stegopidæ, from the Coal Measures
           of Ohio                                                 112-114

    XVI. The Microsaurian Family Urocordylidæ, from the Coal
           Measures of Nova Scotia                                 115-125

   XVII. The Microsaurian Family Amphibamidæ, from the Coal Measures
           of Mazon Creek, Illinois                                136-134

  XVIII. The Microsaurian Family Nyraniidæ, from the Coal Measures
            of Ohio                                                135-138

    XIX. The Aistopodous Microsaurian Family Ptyoniidæ, from the
           Coal Measures of Ohio                                   139-146

     XX. The Microsaurian Family Molgophidæ, from the Coal Measures
           of Ohio and Mazon Creek, Illinois                       147-154

    XXI. The Microsaurian Family Sauropleuridæ, from the Coal
           Measures of Ohio                                        155-170

   XXII. The Microsaurian Family Ichthycanthidæ, from the Coal
            Measures of Ohio                                       171-174

  XXIII. Supposed Microsaurian Species of Uncertain Relationship   175-177

   XXIV. The Temnospondylous Amphibia from the Coal Measures of
           North America                                           178-197

    XXV. The Stereospondylous Amphibia from the Coal Measures of
           North America                                           198-201

          Bibliography of the Fossil Amphibia, With Especial
            Reference to the Amphibia from the Coal Measures of
            North America                                          202-217

          An Index to the Bibliography of Fossil Amphibia          218-219

          Index                                                    220-222



ILLUSTRATIONS.


PLATES.

                                                                      PAGE.

   1. Views along Mazon Creek, Illinois                                  12

   2. Drawing of type specimen of Micrerpeton caudatum Moodie, from
        the Coal Measures of Mazon Creek                                 52

   3. Specimens of Eumicrerpeton parvum, Erpetobrachium mazonensis,
        Erierpeton branchialis, Mazonerpeton longicaudatum, and
        Amphibamus grandiceps                                            58

   4. (1 and 2) Vertebræ of Spondylerpeton spinatum Moodie.
      (3) Type specimen of Mazonerpeton costatum Moodie.
      (4) Type skeleton of Cephalerpeton ventriarmatum Moodie.
      (5 and 6) The halves of the nodule containing a practically
        complete skeleton of Amphibamus grandiceps Cope                  60

   5. (1) A reconstruction of the Coal Measures branchiosaurian,
            Eumicrerpeton parvum Moodie, a small primitive salamander    64

      (2) A restoration of the branchiosaurian, Mazonerpeton, based on
            two specimens                                                64

   6. Dendrerpeton acadianum Owen. Mandibles, parts of anterior
        extremities, humerus, etc.                                        68

   7. Hylerpeton dawsoni Owen. Mandible, teeth, rib, and bones of
        anterior extremity. Bones of pelvis and posterior limb and
        bony scales                                                      72

   8. Fritschia curtidentata Dawson. Bones of skull and anterior
        extremity, bony rods of belly, of pelvis, and posterior
        extremity                                                        76

   9. Hylonomus lyelli Dawson. (1) maxillæ and skull bones;
        (1_a_) sternal bones; (2) mandible; (3) humerus, ribs,
        and vertebræ; (4) posterior limb; (5) pelvis; (6) caudal
        vertebræ                                                         78

  10. Hylonomus latidens Dawson. Skull, portion of skeleton, foot,
        scapular, and sternal bones, humerus and rib, believed to
        belong to this species. Erect tree, Coal formation, of Nova
        Scotia                                                           80

  11. Hylerpeton longidentatum Dawson. Mandible and other bones. Erect
        tree, Coal formation                                             82

  12. Smilerpeton aciedentatum Dawson. Mandible, portions of skull,
        scales, and various bones. Erect tree, Coal formation            82

  13. Dendrerpeton oweni Dawson. Skull, mandible, and bones of
        anterior limbs, posterior limb, pelvic, and bony scales         100

  14. (1 and 2) Amphibamus grandiceps Cope, from the Mazon Creek shales 106
      (3) Sauropleura (Colosteus) scutellata Newberry, from the Linton
           Coal Measures, the first known of the Ohio Coal Measures
           Amphibia; at first ascribed by Newberry to the fishes, but
           later correctly identified by Cope                           106
      (4) Type of Diceratosaurus (Ceraterpeton) punctolineatus Cope,
            from the Linton Coal Measures                               106

  15. (1) Dorsum of skull of Diceratosaurus punctolineatus (Cope),
            from the Coal Measures of Linton, Ohio                      114
      (2) Ventral surface of skull of Diceratosaurus punctolineatus
            (Cope), from the Coal Measures of Linton                    114
      (3) Pectoral girdle of Diceratosaurus punctolineatus (Cope),
            from the Coal Measures of Linton                            114
      (4) Cervical or anterior dorsal vertebra of Diceratosaurus
            punctolineatus (Cope), from the Linton Coal Measures        114

  16. (1) Type specimen of Diceratosaurus punctolineatus Cope           116
      (2) Skull of Sauropleura longidentata Moodie, from the Coal
            Measures of Linton, Ohio                                    116
      (3) Mandible of Sauropleura longidentata Moodie, from the Coal
            Measures of Linton, Ohio                                    116
      (4) Type specimen of Sauropleura enchodus Cope, from the Coal
            Measures of Linton, Ohio                                    116
      (5) Additional specimen of Diceratosaurus punctolineatus Cope,
            from the Coal Measures of Linton, Ohio                      116

  17. Type of Saurerpeton latithorax Cope                               126

  18. (1) Type of Erpetosaurus sculptilis Moodie, from the Cannelton
            Shales of Pennsylvania                                      132
      (2) Skeletal elements of Eryops sp. indet., from the Pittsburgh
            Red Shale at Pitcairn                                       132
      (3) Amphibian footprints, Dromopus aduncus Branson, from the
            Mississippian shales of Giles County, Virginia              132
      (4) Type of Thinopus antiquus Marsh, amphibian footprint from
            the Devonian of Pennsylvania                                132

  19. Type of Ctenerpeton alveolatum Cope, from the Coal Measures
        of Ohio                                                         134

  20. (1) Skull of Erpetosaurus minutus Moodie, from the Cannelton
            slates of Pennsylvania                                      154
      (2) Skull and anterior part of body of Ptyonius pectinatus Cope,
            from the Coal Measures of Linton                            134
      (3) Skeleton of Eosauravus copei Williston, from the Coal
            Measures of Linton. "The oldest known reptile from
            North America" and closely related structurally to the
            Microsauria                                                 134
      (4) Part of ventral scutellation and ribs of Sauropleura digitata
            Cope, from the Coal Measures of Linton                      134

  21. (1) Mandible of Macrerpeton deani Moodie, from the Linton Coal
            Measures                                                    136
      (2) Portion of the skull of Macrerpeton deani Moodie, possibly
            of the same: individual us the mandible. From the Linton
            Coal Measures                                               136
      (3) Type of Cercariomorphus parvisquamis Cope, from the Linton
            Coal Measures                                               136
      (4) An additional specimen of Cercariomorphus parvisquamis Cope,
            from the Linton Coal Measures                               136
      (5) Skull of Sauropleura scutellata Newberry. From the Coal
            Measures of Ohio                                            136
      (6) Tooth of Mastodonsaurus sp. indet. of the Carboniferous of
            Kansas                                                      136
      (7) Tooth of Mastodonsaurus giganteus Jaeger, from the Triassic
           of Germany. Introduced for comparison with the tooth from
           the Kansas Carboniferous                                     136

  22. (1) Type of Leptophractus lineolatus Cope, from the Coal Measures
            of Linton. Portions of maxilla and mandible of left side
            with teeth                                                  160
      (2) Type of Proterpeton gurleyi Moodie, from the Coal Measures
            of Illinois, near Danville. Cervical of an otherwise
            unknown amphibian                                           160
      (3) Amphibian phalanx from the Coal Measures near Breeze,
            Illinois, of an unknown species                             160
      (4) Large rib of a stereospondylous stegocephalan, otherwise
            unknown                                                     160
      (5) Type of Cope's species Tuditanus mordax referred by him to
           the cranium, on account of the sculpturing of the elements,
           now known to be portions of the interclavicle and clavicles
           of Diceratosaurus punctolineatus                             160
      (6) Skull of Baphetes planiceps Owen, from the Coal Measures of
          Nova Scotia                                                   160

  23. (1) Ventral scutellæ of Ctenerpeton alveolatum Cope, from the
            Coal Measures of Ohio                                       166
      (2) Left leg and pelvis of Ichthycanthus platypus Cope, from the
            Coal Measures of Ohio                                       166

  24. (1) Type specimen of Pelion lyelli Wyman, from the Coal Measures
            of Ohio. Supposed to represent the ancestral form of the
            Salientia                                                   172
      (2) Scales of Cercariomorphus parvisquamis Cope, a microsaur
            from the Ohio Coal Measures                                 172
      (3) Type specimen of Cercariomorphus parvisquamis Cope            172

  25. (1) Photograph of type specimen of Erpetosaurus (Tuditanus)
            radiatus Cope, from the Coal Measures of Linton             180
      (2) Photograph of type specimen of Erpetosaurus tabulatus Cope,
            from the Coal Measures of Linton                            180
      (3) Photograph of the impression of Stegops divaricata Cope,
            from the Coal Measures of Linton                            180
      (4) Type and only known specimen of Micrerpeton caudatum Moodie,
            a branchiosaur from the Coal Measures shales of Mazon Creek 180

  26. (1) Type specimen of Erpetosaurus tuberculatus Moodie, from the
            Ohio Coal Measures                                          182
      (2) Type of Macrerpeton huxleyi Cope, from the Coal Measures
            of Ohio                                                     182


TEXT-FIGURES.

   1. Map of the Coal Measures in North America                           9

   2. Distribution of Coal Measures Amphibia in North America            11

   3. Topographical Map of Mazon Creek Region                            13

   4. Topographical Map of Linton, Ohio, Region                          16

   5. Fossil Tree Trunk in Position                                      21

   6. Generalized Amphibian Skull                                        23

   7. Alimentary Canal of a Carboniferous Salamander                     26

   8. Vertebræ and Ribs of Coal Measures Amphibia                        28

   9. Ventral Scutellæ of Micrerpeton                                    30

  10. Horny Armor of Hylonomus                                           31

  11. The Skulls of two Microsaurians: A, Eoserpeton tenuicorne;
        B, Ceraterpeton galvani                                          33

  12. Devonian Footprint                                                 37

  13. Restoration of Micrerpeton                                         53

  14. Mazon Creek Amphibia: A, Eumicrerpeton parvum;
        B, Amphibamus thoracatus                                         59

  14_a_. Skeleton of Mazonerpeton longicaudatum                          62

  14_b_. Skeleton of Mazonerpeton costatum                               64

  15. A. Impression of Erierpeton branchialis                            65
      B. Eumicrerpeton parvum                                            65
      C. Larger Specimen of Eumicrerpeton parvum                         65
      D. Skeleton of Erpetobrachium mazonensis                           65
      E. Rib of Mazonerpeton costatum                                    65

  15_a_. Type Material of Sparodus                                       66

  16. Obverse of Cocytinus gyrinoides                                    68

  16_a_. Nearly Complete Specimen of Cocytinus gyrinoides                69

  17. Pelion lyelli, supposed ancestral Salientian                       74

  18. Skeletal Elements of Smilerpeton aciedentatum                      82

  19. Skull and Skeleton of Tuditanus punctulatus                        87

  20. Skull and Skeleton of Tuditanus longipes                           90

  21. Skeleton of Tuditanus walcotti: A, Body; B, Leg                    94

  22. A. Outline of Skull and Cranial Elements of Erpelosaurus minutus
           Moodie, from the Cannelton Slates of Pennsylvania             99
      B. Outline of Skull and Cranial Elements of Erpetosaurus radiatus
           Cope, from the Coal Measures of Linton                        99
      C. Palate of Erpetosaurus (tabulatus?), from the Coal Measures of
           Linton, Ohio                                                  99
      D. Outline of Skull and Cranial Elements of Erpetosaurus
           acutirostris Moodie, from the Coal Measures of Linton, Ohio   99
      E. Outline of Larger Part of Skeleton of Odonterpeton triangularis
           Moodie, from the Coal Measures of Linton, Ohio                99
      F. Right Mandible of Erpetosaurus tabulatus Cope, from the Linton,
           Ohio, Coal Measures                                           99
      G. Skull Elements and Lateral-line Canals of Erpetosaurus
           tabulatus Cope, from the Coal Measures of Linton              99

  23. Skull of Stegops divaricata                                       113

  24. Microsaurian Skulls from Linton, Ohio: A, Diceratosaurus lævis;
        B, Diceratosaurus robustus                                      119

  25. Restoration of Eoserpeton                                         124

  26. Restoration of Amphibamus                                         128

  27. Skeleton of Amphibamus grandiceps                                 129

  28. Probable Appearance of Amphibamus                                 130

  29. Skeleton of Cephalerpeton                                         133

  30. Restoration of Ptyonius                                           140

  31. Restoration of Œstocephalus                                       144

  32. Vertebræ of Molgophis brevicostatus                               148

  33. Fore-limb of a Member of the Molgophidæ, Possibly Pleuroptyx      152

  34. A. Interclavicle of Sauropleura pauciradiata                      159
      B. Left Clavicle of Sauropleura pauciradiata                      159

  35. Skull and Skeleton of Saurerpeton latithorax                      164

  36. Mandible of Leptophractus dentatus                                169

  37. So-called Interclavicle of Eurythorax sublævis                    170

  38. Skeletal Elements of Amblyodon                                    177

  39. Vertebra of Spondylerpeton spinatum                               179

  40. Mandible of Macrerpeton deani                                     184

  41. Vertebræ of Eosaurus acadianus: A, Oblique Lateral View;
        U, Oblique View; C, Posterior View; D, Transverse
        Section; E and F, Microscopic Sections                          188

  42. Skull and Mandible of Eobaphetes kansensis: A, Outer View of
        Mandible; B, Portion of Skull; C, Inner Surface of Mandible     191

  43. Footprints of Dromopus agilis                                     200



                    ===============================

                      THE COAL MEASURES AMPHIBIA
                           OF NORTH AMERICA

                    ===============================



CHAPTER I.

THE PROBLEM OF THE AMPHIBIA FROM THE COAL MEASURES.


The Amphibia from the Coal Measures of North America present the
problem of the origin of the land vertebrates, since the air-breathing
vertebrates in the Coal Measures of this continent are the earliest
known in the western hemisphere. The difference in age between the
chief amphibian-bearing deposits of North America and Europe is not
great, although it has been asserted that _Pholidogaster_ and its
allied fauna, described by Huxley from Scotland (331), is much older,
probably Mississippian. It is interesting to note that these earliest
representatives of the Amphibia in Scotland are all temnospondyles, of
which there are very few representatives in the Coal Measures of North
America.

The forms so far described from the North American Coal Measures present
a very high degree of development and differentiation, the earliest known
species being already specialized and well adapted for various modes of
life. As far back in geological time as the middle Coal Measures, when
the first well-defined forms are known, environmental conditions had
effected a wide diversity of structure within the group. Thus, early in
the geological history of the land vertebrates, we have, among the Coal
Measures Amphibia, various forms which had specialized into strictly
aquatic, terrestrial, subterrestrial, and arboreal, or at least partly
arboreal. Specialization had extended to the loss of limbs, ribs, and
ventral armature in a few species, and to the acquirement of claws,
running legs, or a long propelling tail with expanded neural and hæmal
arches in others. The forms range in size from small creatures less than
an inch in length to large species which must have attained a length of
several feet. A rather interesting parallel, though of no phylogenetic
significance, can be drawn between the Amphibia of the North American
Coal Measures and the reptiles of to-day. The snakes are represented by
the limbless, snake-like forms, such as _Ptyonius_ and _Phlegethontia_.
The lizards find their counterpart in the Hylonomidæ and the Tuditanidæ.
No known characters of these animals tend to ally them directly with any
known group of fishes, except in the most general way. These facts all
indicate a long antecedent history for the amphibian group or else a
preceding period of greatly accelerated development of which we now know
nothing.

The Amphibia whose remains have been brought to light from the Coal
Measures have hitherto been regarded as pertaining to a single order, the
Stegocephalia, characterized by the completely roofed-over cranium and a
large parasphenoid. The writer (469) had previously assigned 5 suborders
to the group: the Branchiosauria, Microsauria, Aistopoda, Temnospondylia,
and Stereospondylia. All of these groups are represented in the Coal
Measures of North America. It has seemed inadvisable, in the light of our
present knowledge of the Amphibia, to retain these 5 groups as suborders,
and, in the revised scheme of classification which has been published
elsewhere (469), they are given the rank of orders all excepting the
Aistopoda, which are now regarded by the writer as specialized Microsauria.

The recent Caudata are possibly represented in the North American Coal
Measures by forms which may be assigned tentatively to the Proteida.
Such forms as _Cocytinus gyrinoides_, _Hyphasma lævis_, and _Erierpeton
branchialis_ possibly represent this group in the Pennsylvanian. This
relationship is based chiefly on the structure of the hyobranchial
apparatus and on the general structure of the species. The three
above-mentioned species are, however, very insufficiently known, and
the relationship can hardly be regarded as more than suggested by the
characters which are at hand.

The Salientia, or frogs, may possibly have their ancestral type in _Pelion
lyelli_, the first known species from the Linton, Ohio, Coal Measures.
Oddly enough, among the hundreds of specimens collected later from this
horizon, not a fragment can be identified with this species. The type
specimen is unique, and although incomplete its characters are suggestive.

The Branchiosauria are represented in North America by four species:
_Micrerpeton caudatum_, _Eumicrerpeton parvum_, _Mazonerpeton
longicaudatum_, and _M. costatum_. Three other genera which occur in North
America have been placed (642) in this group, but they do not belong
there, for reasons given below. The branchiosaurs were salamander-like
in appearance. They were naked, with the exception of small ovoid scales
on the back and the chevron-shaped armature of the ventral surface, the
latter being almost universally present among the Paleozoic Amphibia. They
were adapted for life in the water for at least the early part of their
existence, as is shown by the possession of gills on many of the late
Carboniferous and early Permian forms of Europe. The group is, without
doubt, ancestral to the modern Caudata. No branchiosaurians have been
described elsewhere from so low in the geological series as those here
given and they are the first and only evidence of the occurrence of the
group in the western hemisphere.

The Microsauria are represented in the Coal Measures by numerous
forms which are usually characterized as lizard-like animals with a
well-developed ventral scutellation. Other characters, such as the
possession of lateral-line grooves on the cranium, the arrangement of the
cranial elements, and the condition of the ribs, will be discussed further
on. The pectoral arch is well developed and is composed of five dermal
bones plus the regular skeletal elements. The skeletal membrane bones are
sculptured after the manner of those of the cranium. The bodies of the
animals were, in a few cases, covered with scales; but most of them appear
to have been completely naked, even the ventral armature being absent in
some cases. The ventral scutellation was especially strong and highly
developed in some of the forms; _e.g._, in the genera _Saurerpeton_ and
_Sauropleura_. The vertebræ are uniformly of the hour-glass or notochordal
type. This is so generally the case that the characters of the vertebræ
and ribs are taken as the chief diagnostic characters of the major
groups. Various peculiarities are seen among the Microsauria, such as the
development of horns in various genera which are, apparently, related.
The order seems to have gone completely out of existence during the early
Permian, and if their descendants continued on as reptiles, as has been
suggested (469), we do not know the intermediate stages.

The Aistopoda are without doubt specialized microsaurs, and, in the
opinion of the writer, are not entitled to separate rank. Some of these
forms reached a high degree of specialization. One American species has
the skeleton reduced to a long, slender head and a slender series of
elongate vertebræ, all other parts of the skeleton, even the ventral
armature, being absent. The proportions attained by this species,
_Phlegethontia linearis_ Cope, recall those of the coach-whip snake,
_Zamenis flagellum_ Shaw, of the western plains. Some of the so-called
Aistopoda have been credited by Fritsch with the possession of peculiar
clasping organs, "Kammplatten." Newberry has written of the discovery of
similar structures in the Ohio Coal Measures (498), but the statement of
the actual association of these "Kammplatten" needs confirmation. Dr. R.
H. Traquair wrote to the author under date of April 28, 1909:

"I maintain that the association of a bundle of 'Kammplatten' with
a specimen of _Ophiderpeton_ in the Bohemian gas coal was entirely
_accidental_. Of such pitfalls the paleontologist has to beware or serious
mistakes may be the consequence, as has happened more than once. I must,
however, publish a short paper on the Kammplatten, for I think I know what
they are now."

Fritsch, however, has very clearly figured a nearly complete specimen
of _Ophiderpeton_ (251, Bd. IV) as possessing the Kammplatten in place
near the cloaca, where he suggests they may have served the function of
accessory copulatory organs or claspers.

The Temnospondylia are represented by scanty remains of species from
Illinois, Pennsylvania, and Nova Scotia. The forms belonging to this group
are all relatively large, and they had a wide geographical distribution
during the Permian. This group contains two types of vertebræ, known
as the embolomerous and the rachitomous, both of which are present in
the Coal Measures. Such forms as _Eosaurus_, _Baphetes_, _Eobaphetes
kansensis_, _Macrerpeton_, and _Dendrerpeton_ are regarded tentatively as
temnospondyles, but there is no definite assurance that they are such.
It is possible that _Eosaurus_ is a stereospondyle, but the species is
too incompletely known for a definite statement to be made. The close
resemblance between the vertebræ of _Eosaurus_ and _Anthracosaurus_ has
been noted by Huxley (332).

The Stereospondylia are very scantily represented in the Coal Measures,
if at all. _Eosaurus_ may belong here as indicated above. The tooth and
cranial fragments discovered and described by Williston from the Coal
Measures of Kansas may represent a stereospondyle as he states (608),
but the evidence is incomplete. A fragment of a large rib (plate 22,
fig. 4) of a species from Linton, Ohio, otherwise unknown, may be a
stereospondyle. We would expect an early development for this group,
but it is' an interesting fact that no stereospondyles are known
definitely before the Triassic, during which period they had an extensive
distribution.



CHAPTER II.

HISTORY OF THE DISCOVERY OF AMPHIBIA IN THE COAL MEASURES.


Sir William Logan, in 1841, discovered in the Coal Measures of Horton's
Bluff, Nova Scotia, some tracks of Amphibia which he carried to London
and which Sir Richard Owen pronounced to be undoubted "reptilian" tracks.
This fact was published in 1842 (380) and was the first recorded evidence
of the occurrence of land vertebrates in the Carboniferous rocks of the
world. To these tracks Sir William Dawson later gave the name of _Hylopus
logani_.

Two years later Dr. Gergens (291) wrote a letter to Professor Bronn, the
founder and one of the editors of the "Neues Jahrbuch für Mineralogie,
Geologic und Paleontologie," in regard to an important discovery in the
Carboniferous rocks of Germany. The letter is of such exceptional interest
in connection with the history of the fossil Amphibia that it is given
here:

  "In dem Brandschiefer von Münsterappel in Rhein-Bayern habe ich in
  vorigen Jahre einen Salamander aufgefunden und Hrn. H. v. Meyer in
  Frankfurt zur näheren Untersuchung und Beschreibung übergeben;--Gehört
  dieser Schiefer der Kohlen-Formation?--in diesem Falle ware der Fund
  in anderen Hinsicht interessant."

The form discovered by Dr. Gergens and described by Hermann von Meyer as
an amphibian is a little puzzling as to its characters. Miall (449, p.
183) says that the remains are too imperfect for close definition. The
form, as figured, resembles an immature branchiosaurian, as one is at once
reminded, from an examination of Von Ammon's _Branchiosaurus caducus_ (7,
Taf. IV, fig. 1). In 1844 Dr. Alfred King (356) announced the discovery of
"reptilian" footprints in the Carboniferous of Pennsylvania.

The next announcement of fossil Amphibia was made by Goldfuss (296), who
in 1847 described the famous _Archegosaurus_ from the upper Carboniferous
of Germany, from the remains which had as long ago as 1777 been
regarded as a fish. Two years later Isaac Lea (371) announced to the
British Association for the Advancement of Science, through Buckland,
the discovery of footprints in the old Red Sandstone (Mauch Chunk) of
Pennsylvania. These objects occur not rarely in the Mauch Chunk shales,
which are of upper Mississippian age. Barrell (21, p. 460) records the
finding of imperfect tracks in the same beds, and Rogers (Geology of
Pennsylvania, pt. II, 1856, p. 831) records three unnamed varieties from
2,200 feet below the top of the Mauch Chunk. Branson (50) has recorded
the finding of other amphibian footprints from the Mississippian of Giles
County, Virginia.

Lyell and Dawson (396), in 1853, read a paper before the Geological
Society of London, in which they announced the discovery of remains of
Amphibia in the Coal Measures of North America, although Dawson had
previously, in 1850, discovered the skull of _Baphetes planiceps_ Owen,
which was not described until the latter part of 1853 (509). The specimen
had lain unnoticed in the collection of the Geological Society for more
than two years. When, however, the announcement was made by Lyell and
Dawson of the discovery of Amphibia in the Coal Measures of Nova Scotia,
so much interest was excited that the skull, now known as _Baphetes
planiceps_, was brought to light by the president or secretary and was
described (509) by Sir Richard Owen. The only other known evidences of
land vertebrates in the Paleozoic of North America, up to this time, had
been the footprints described by Lea and King from the Mississippian
(Mauch Chunk) and Pennsylvanian of Pennsylvania. The specimens presented
to the Geological Society of London by Lyell and Dawson were found at the
South Joggins, Nova Scotia, and consisted of scutes, a few limb bones, a
fragment of a jaw, and a few vertebræ, a part of which were associated.
The remains were found quite accidentally and unexpectedly by them in
the petrified trunks of ancient Sigillariæ which were exposed on the
coast. Dr. Jeffries Wyman, of Harvard College, had examined these remains
in the United States and had pronounced (638) them to be amphibian,
comparing them with similar elements in _Menobranchus_. On the arrival
of the specimens in England they were submitted to Sir Richard Owen,
who suggested the name (514) _Dendrerpeton acadianum_ and compared the
remains with _Archegosaurus_. At the same meeting of the London Geological
Society, Owen read a paper on a small amphibian (508) from the British
Carboniferous which he named _Parabatrachus_. Subsequent discoveries have
shown, however, that this form belongs among the fishes. At the meeting
of the Geological Society held in the latter part of the same year Owen
announced (509) further discoveries in the Nova Scotia coal beds.

Hermann von Meyer (436), in 1857, described numerous stegocephalian
remains from the upper Carboniferous of Germany. Dr. Jeffries Wyman, in
the same year, described (639) a new form of amphibian from Linton, Ohio.
This form he called _Raniceps lyelli_, but as the name _Raniceps_ had been
preoccupied by Cuvier for a genus of gadid fishes, Wyman later (1868)
changed the name to _Pelion_. This was the first form to be described from
the locality at Linton, which has since yielded the remains of half a
hundred species.

Dawson (204), in 1859, made a further contribution to the fauna of
Nova Scotia by the description of _Hylonomus_ and other species of
_Dendrerpeton_ from the South Joggins deposits. Huxley (331), in 1862,
described the genera _Loxomma_ and _Pholidogaster_ from the Carboniferous
of Scotland. The same year Owen made a further contribution (514) to the
fauna of the Nova Scotia beds, and Huxley (332) discussed the anatomy of
_Anthracosaurus_ from Scotland. Marsh (404), in the next year, described,
as an enaliosaurian, the interesting _Eosaurus acadianus_ from the Nova
Scotia Coal Measures, basing the species on two vertebræ, apparently from
the dorsal region. The vertebræ resemble the stereospondylous type, and
Huxley (332) called attention to the similarity of these vertebræ to those
of _Anthracosaurus_.

Cope (105), in 1865, began his researches among the Coal Measures Amphibia
of North America by the description of _Amphibamus grandiceps_ from the
Mazon Creek shales of Illinois. Ten years later (123) he published a
complete synopsis of the Carboniferous Amphibia of North America, with
especial reference to the Linton, Ohio, species, illustrating many of
the forms now known from Linton. Between the years 1865 and 1897, Cope
published numerous papers (105-177) on the Amphibia of the Paleozoic, and
to his researches is due a large part of our knowledge of these forms.

Great credit is due Dr. J. S. Newberry (495, 498) for the enthusiasm and
interest which his collections of Coal Measures Amphibia exhibit. He
furnished Cope with the majority of the type material described by him,
and it was through Dr. Newberry's instrumentality that the "Synopsis of
the Extinct Batrachia from the Coal Measures" (123) was published. The
material which Dr. Newberry had collected he took with him from Ohio to
Columbia University, New York, and a part of his collection still remains
in the geological collection of that institution, although the greater
portion has been transferred to the American Museum of Natural History.
The Newberry collection forms the basis for the larger part of this memoir.

Between the year 1853 and the early nineties, Dawson continued (200-223)
his researches on the Amphibia of the Coal Measures of Nova Scotia. His
most notable single work (208) is "The Air-Breathers of the Coal Period,"
published in Montreal in 1863, in which he gives a complete account of
the forms then known from Canada, attempting some restorations. Since his
death there have been no new species described from Canada, and, so far as
I can learn, there has been no further collecting at the South Joggins.

Recently G. F. Matthew (409) has rearranged the classification of
amphibian footprints from Nova Scotia. Jaekel (347) has described very
fully the remains of _Diceratosaurus punctolineatus_ (Cope) from Linton,
Ohio, basing the new genus on a species described by Cope as a member of
_Ceraterpeton_. Hay (316) has added to the knowledge of the anatomy of
_Amphibamus_, his most interesting contribution being the detection of
long, curved ribs in this form. This character excludes the species from
the order Branchiosauria and shows the relationship of the form to the
Hylonomidæ and the Microsauria. Schwarz (540) has described the characters
of the vertebræ and ribs of several genera of the Coal Measures Amphibia
and has (541) offered his views as to the descent of the Amphibia, based
entirely on his work on the vertebræ of species from North America and
Europe.

Since 1908 the writer has published several contributions (457-489) on the
Amphibia from the Coal Measures of North America. The results of these
investigations are given in this work.



CHAPTER III.

STRATIGRAPHIC AND GEOGRAPHIC DISTRIBUTION OF AMPHIBIA IN THE COAL MEASURES
OF NORTH AMERICA.


There are but four localities in North America which have furnished any
notable remains of Amphibia in the Coal Measures. These are, in the order
of their discovery, the deposits at the South Joggins, Nova Scotia; the
Linton, Ohio, Coal Measures; the Mazon Creek, Illinois, shales; and the
Cannelton slates near Cannelton, Pennsylvania. There are, however, several
other localities on the continent which have furnished evidences of
Amphibia in the Coal Measures. The principal one of the latter localities
is doubtfully of Coal Measures age, although recent discoveries would tend
to show it is such. The deposits in question, those of the Clepsydrops
shales of Vermilion County, Illinois, have, heretofore, been regarded
as Permian, but the discovery of similar remains in rocks of undoubted
Pennsylvanian age in Pennsylvania would seem to indicate that the Illinois
deposits were contemporaneous with them.

[Illustration: Fig. 1. Map of Upper Pennsylvanian showing land and water
conditions under which the Coal Measures amphibian fauna lived. It will be
noted that the chief deposits which have furnished amphibian remains are
on the margins of the heavily shaded areas. (After Schuchert.)

Explanation of symbols: Lands are white. Water areas are lined. Formation
outcrops are black or dotted. Known shore-lines are solid lines; probable
ones broken. Vertical lines in middle of continent indicate Gulf marine.]

(_a_) The deposits in Vermilion County, Illinois, lie along the north bank
of Salt Fork Creek, at the tip of the "Horseshoe Bend," about 2 miles
south of Oakwood, Illinois. They were discovered by Dr. J. C. Winslow,
of Danville, in 1875. The remains discovered by him were forwarded to
Professor Cope for identification. Later the deposits were thoroughly
explored by W. F. E. Gurley, and the specimens collected by him are now
preserved (86) in Walker Museum, University of Chicago. In 1907, the
writer, while working for the University of Chicago, in exploring the
same locality, exhausted the beds so far as they could at that time be
uncovered from the landslide which had overwhelmed them. The formation
in which the bones occur is a soft gray or reddish shale, and it lies
without any apparent stratigraphic break on shales of Pennsylvanian age.
Below these shales are several feet of limestone containing invertebrates
of typical Pennsylvanian facies. There are indications of at least 3
species of Amphibia in the deposits. Case (86) has indicated with doubt a
fourth species. The species are: _Cricotus heteroclitus_ Cope, _Cricotus
gibsonii_ Cope, _Diplocaulus salamandroides_ Cope. The remains are very
fragmentary, and consist for the most part of incomplete vertebræ, with a
few small skull fragments.

(_b_) In 1897 Dr. Williston (607) described some fragments of _Cricotus_
from a deposit in Cowley County, near Winfield, Kansas. There has been
some dispute as to the age of the deposit, but the consensus of opinion
seems to be that the beds are of approximately the same age as those of
Illinois and Pennsylvania in which similar remains are found, and those
deposits are looked upon as Upper Pennsylvania (Case (94), pp. 239-240).
No new forms were described from Winfield, since only a few fragments were
obtained. Williston referred the phalange, the fragment of a jaw, and the
tooth to _Cricotus heteroclitus_ Cope.

(_c_) Later in the same year Williston (608) announced the discovery of
a tooth of typical labyrinthodont structure from near Louisville, Kansas
(plate 21, fig. 6). The tooth was accompanied by fragments of bone and was
probably not far from the bed in which it was fossilized. Williston states
that the remains were from the shales which are "nearly at the upper part
of the Carboniferous, probably within one hundred feet of the Manhattan
Limestone."

(_d_) In 1894 Marsh (406) and earlier (1873) Mudge (490) described
footprints of vertebrates from the stone-quarries near Osage City, Kansas.
The stone in which they were found was a fine-grained limestone which
occurs near the middle of the Kansas Coal Measures.

(_e_) Two years later Marsh (407) announced the discovery of traces of
the oldest known (Devonian) air-breathing vertebrate. The footprints of
_Thinopus antiquus_ were regarded by Marsh as "apparently amphibian." This
still remains the oldest geological evidence of air-breathing vertebrates,
although Lohest some years ago (381) called attention to remains from the
Devonian of France which he thought might be amphibian. The footprint
described by Professor Marsh was "found in the town of Pleasant, one
mile south of the Allegheny River, Warren County, Pennsylvania, by Dr.
Charles E. Beecher, who presented it to Yale Museum, and also furnished
the information in regard to its geological position.... The geological
horizon is near the top of the Chemung, in the upper Devonian. In the
same beds are ripple marks, mud cracks, and impressions of rain drops,
indicating shallow water and shore deposits."

(_f_) Among the collections of the American Museum there is an impression
of a small amphibian foot obtained from Phoenix Tunnel, Pennsylvania.
The impression is in hard black slate very similar to the slate of the
Cannelton region. It is possible that the specimen may have been obtained
from the Cannelton beds, since they would be expected to occur at Phoenix
Tunnel. The impression is rather small. It is the footprint of a 5-toed
animal, probably of the right foot, since no amphibian (465) so far is
known from the Coal Measures with 5 digits on the hand. The first digit
is short and thick, with a large ball at its base. The foot measures from
the posterior edge of the palm to the tip of the longest digit 12 mm. The
length of the first digit is 7 mm. The impression differs in some respects
from the impressions so far known from the Coal Measures, but no attempt
will be made to assign it to a species. It may have been made by either
a branchiosaurian or a microsaurian, but more probably the latter, since
we do not know of any of the former animals from the Cannelton beds, or in
fact from any of the Coal Measures beds excepting the Mazon Creek shales.
The specimen is No. 2872 of the American Museum.

[Illustration: Fig. 2. Distribution of Coal Measures Amphibia in North
America.

  1. Linton, Ohio, near Yellow Creek P. O., Jefferson County, Ohio, on
       the banks of Yellow Creek, near the Ohio River, 16 miles north of
       Steubenville.

  2. Mazon Creek shales, Grundy County, Illinois, near Morris.

  3. "Clepsydrops shales," Salt Fork Creek, Vermilion County,
       Illinois, near Oakwood, on Tate farm, 8 miles west of Danville,
       Illinois.

  4. Danville, Illinois, coal where the type of _Proterpeton gurleyi_
       Moodie was found.

  5. Breeze, Illinois, where Dr. J. A. Udden, in 1907, found a
       fragment of an amphibian phalange on the dump of the Cooperative
       Coal Company.

  6. Pitcairn, Pennsylvania, 15 miles east of Pittsburgh.

  7. Cannelton, Pennsylvania, Beaver County, Cannelton slates,
       Kittanning formation, 45 miles northwest of Pittsburgh.

  8. Fairfield, Iowa, where Dr. J. A. Udden found remains attributed
       by Dr. Eastman to _Pleuroptyx clavatus_ Cope.

  9. Louisville, Pottawatomie County, Kansas, where Dr. S. W.
       Williston discovered remains of Mastodonsaurus in the Coal
       Measures.

  10. Washington County, Kansas, source of type of _Eobaphetes
       kansensis_ Moodie, from the Coal Measures.

  11. Osage City, Osage County, Kansas, amphibian footprints from the
       Coal Measures.

  12. Winfield, Kansas, source of Cricotus material.

  13. Lander, Wyoming, in Wind River Carboniferous.

  14. Pictou, Pictou County, Nova Scotia, 84 miles northeast of
       Halifax. Source of _Baphetes planiceps_ Owen.

  15. Joggins (Joggins Mines), Cumberland County, Nova Scotia, 4 miles
       from River Hebert. Source of _Hylerpeton_ and _Dendrerpeton_
       faunas.

  16. South Joggins, Nova Scotia, source of the _Eosaurus acadianus_
       Marsh.

]

(_g_) Dr. J. A. Udden, in 1907, discovered a fragment of a phalanx of some
amphibian (plate 22, fig. 3) on the dump of the Cooperative Coal Company,
a mile east of Breeze, Illinois. It was obtained from below the Shoal
Creek limestone and somewhere above the (Illinois) Coal No. 6, according
to Dr. Udden's notes. The maximum width of the phalanx is 10 mm. and it
probably had a length of 16 mm.

(_h_) Mr. N. H. Brown, in 1914, discovered in the Carboniferous rocks
to the east of the Wind River Mountains, near Lander, Wyoming, a single
fragment of an amphibian. The writer was accompanying Mr. Brown at the
time of the discovery and there can be no doubt that the fragment was
amphibian; the location of the beds was such that no later age than the
Coal Measures can be assigned to them.

(_i_) Dr. J. A. Udden (577), in 1912, announced the discovery of an
amphibian in the Des Moines formation of Iowa. These remains were
identified by Dr. Charles Eastman as _Pleuroptyx clavatus_ Cope. Since the
Des Moines is probably nearly contemporaneous with the Mazon Creek shales
of Illinois, the discovery does not extend the geological range to any
extent, but is of interest as it adds another note to our knowledge of the
geographical distribution of the Amphibia in the Coal Measures.

(_j_) The Gurley collection of the University of Chicago possesses a
single cervical vertebra of some amphibian (?). The vertebra is unlike
anything previously described and represents a new form (plate 22, fig. 2)
which may be designated _Proterpeton gurleyi_, new genus and species. The
material was collected near Danville, Illinois.

(_k_) Deposits have been discovered in Pennsylvania in which are found the
remains of amphibians and reptiles, very similar to those from Vermilion
County, Illinois, Cowley County, Kansas, and the Texas Permian. The
remains (plate 18, fig. 2) were found in a thin stratum below the "Ames"
limestone, and are therefore in the Coal Measures, fairly well below the
top. The fossils, as described by Case (94), consist of fragments which
he ascribes to pelycosaurian reptiles and to temnospondylous amphibians.
The genus _Eryops_ (94) is recognized in several fragments and a nearly
complete dorsal vertebral centrum. Other types of Amphibia are likewise
represented.

(_l_) The ironstone nodules, in which the Mazon Creek fossils (plate 1)
occur, are found in the shale which forms the roof of the Morris or "No.
2" Coal of Illinois, which "lies probably somewhat lower than the horizon
of the Lower Kittanning Coal of Pennsylvania" (599). "The nodules of iron
contained in the Coal shales on the banks of Mazon Creek near Morris,
Illinois, generally contain organic nuclei, and thousands of beautiful
specimens have been obtained there. They are usually fragments of fern
fronds, but are sometimes shells, crustaceans, myriapods, scorpions,
spiders, cockroaches, ... fishes" (498, p. 214), and amphibians, of which
10 species are at present known.

[Illustration: MOODIE                                            PLATE 1

VIEWS ALONG MAZON CREEK, ILLINOIS.

  1. A nodule weathering out of the shale, at the head of the hammer.
       Most of the nodules at the so-called "lower beds" contain
       specimens of _Neuropteris_.

  2. The nodules in the creek bed at the "upper beds." Many of them
       have been cracked open by the frost.

  3. Looking south at the "upper beds." The nodules found in the
       background are non-fossiliferous.

  4. Nodules may be seen through the clear water embedded in the
       shale. Neuropterid insects in the water.

  5. Looking for nodules at the "upper beds." The uppermost reaches of
       the fossiliferous beds correspond with the extreme background of
       the picture.

  6. Nodules in the stream bed at the "lower beds." Many of these are
       cracked open by the frost and good specimens are sometimes found
       in the nodules.

]

These species have been arranged zoologically according to the following
plan:

  Class Amphibia Linné, 1758.
    Subclass Euamphibia Moodie, 1909.
      Order Branchiosauria Lydekker, 1889.
        Family _Branchiosauridæ_ Fritsch, 1879.
          _Micrerpeton caudatum_ Moodie, 1909.
          _Eumicrerpeton parvum_ Moodie, 1910.
          _Mazonerpeton longicaudatum_ Moodie, 1912.
          _Mazonerpeton costatum_ Moodie, 1912.
      Order Caudata Duméril, 1806.
        Suborder Proteida Cope.
          Family _Cocytinidæ_ Moodie, 1912.
            _Erierpeton branchialis_ Moodie, 1912.
    Subclass Lepospondylia Zittel, 1887.
      Order Microsauria Dawson, 1863.
        Family _Amphibamidæ_ Cope, 1875.
          _Amphibamus grandiceps_ Cope, 1865.
          _Amphibamus thoracatus_ Moodie, 1911.
          _Cephalerpeton ventriarmatum_ Moodie, 1912.
        Family _Molgophidæ_ Cope, 1875.
          _Erpetobrachium mazonensis_ Moodie, 1912.
    Subclass Stegocephala Cope, 1868.
      Order Temnospondylia Zittel, 1887.
        Suborder Embolomeri Cope, 1885.
          Family _Cricotidæ_ Cope, 1884.
            _Spondylerpeton spinatum_ Moodie, 1912.

It will be seen from the above arrangement that nearly all of the orders
of Amphibia are represented in the Mazon Creek fauna. These animals are
the oldest known land vertebrates of North America.

[Illustration: Fig. 3. Portion of the "Morris sheet" of the U. S.
Geological Survey, to show topography and situations of the exposures
of fossil-bearing shales at Mazon River, _a_, the "Bartlett place," the
so-called "upper beds"; _b_, "lower beds."]

The writer was able, during July 1911, to spend a week studying the
fossil beds (479) at Mazon Creek. The object of the visit was primarily
to collect Amphibia, but although several thousand nodules were examined,
not one contained an amphibian nor a fragment of one. Mr. J. C. Carr,
of Morris, Illinois, who has collected at Mazon Creek for more than 30
years, has never collected an amphibian. These facts interested me in
making the following comparison: If we take 100,000 nodules as a basis
for computation of the rarity of the various forms, something like the
following will be the approximate result of the investigation:

Of 100,000 nodules, 20,000 will be barren or contain only indeterminate
fragments; 68,500 will contain plants; 7,500 will contain insects,
Crustacea, myriapods, scorpions, spiders, and other arthropods; 3,900 will
contain fish coprolites or scales; 95 may contain fish or fragments of
fish; 4 may contain mollusks; and 1 may contain an amphibian or a fragment
of one.

Perhaps even 100,000 is low as a basis of estimate. Mr. Carr was of the
opinion that 1 nodule in every 500,000 might contain an amphibian.

The beds from which the nodules are usually collected occur along both
banks and in the bottom of the creek, in two localities. One locality
known as the Bartlett place is situated 8 miles southeast of Morris, in
Grundy County, Illinois, Wauponsee Township, N.W. quarter, section 30,
Township 33, Range 8, the land being now owned by Mrs. Emma Akerly, of
Wilmington, Illinois.

The fossil-bearing nodules occur throughout 6 to 8 feet of shale along
both banks of the creek at the "upper beds" (plate 1, fig. 3), as the
Bartlett place is called. They may also be seen in the bed of the creek,
when the water is low (plate 1, fig. 4), still embedded in the shale. With
a potato fork the shale is easily turned and the nodules come out like
potatoes. One sometimes finds a "pocket" of nodules from which as many
as a peck may be secured. Nearly every nodule has a fossil at the "upper
beds," but all of the fossils are not well preserved, possibly only 1 or
2 out of every 10 being worth carrying to the museum. The nodules crack
best when wet, and it requires some skill to crack them evenly. They seem
quite light and, in one place where the stream curves, are piled in a long
windrow. On this were found, in nodules cracked by the frost, several good
crustaceans and many good plants.

Table of Pennsylvanic Formations.

  Series   Northern Appalachian. Bituminous.
                 Pennsylvania-Ohio.          Illinois.
  Pennsylvanic
   {
   {  Coal Measures
   {    {                               { (*) (_Salt Fork_).
   {    { Monongahela or Upper          { Break.
   {    {   Productive Coal Measures
   {    {
   {    { Conemaugh or Lower Barren Ames
   {    {   limestone near middle:
   {    {     (*) (_Pitcairn_)                Coal No. 6.
   {    {
   {    {                     { Freeport
   {    { Allegheny or Lower  {  (*) (Cannelton) Coal No. 2 (*).
   {    {    Coal Measures    { Kittanning (*).  (Morris?)(_Mazon Creek_).
   {    {                     {  (_Linton_).
   {    {                     { Clarion.
   {
   {  Pottsville
   {    {
   {    { Home wood.
   {    { Mercer.
   {    { Conoquenessing.
   {    { Sharon.

  (*) marks the position of the Amphibian-producing horizons in
        these regions. (After Schuchert.)

The fossils at the "upper beds" are localized into special strata. At one
place in the upper part of the deposit, in a reddish shale, one finds
that insects are more abundant than they are lower down. The Crustacea
seem to come from apparently the same shale. At the lower end of the
deposit certain definite species of _Pecopteris_ are localized. It is
an interesting fact that one seldom finds a _Neuropteris_ at the "upper
beds." The most abundant fossils are the various species of _Pecopteris_
and _Annularia_. When specimens of _Neuropteris_ are found they are
usually discovered at the lower end of the exposures. In one place behind
the "island" very blue nodules, hard and flinty and with sometimes
well-preserved specimens of _Pecopteris_, are found quite definitely
localized. These nodules are apt to assume an irregular shape. These
localizations of the fossils are, of course, what we would expect from our
knowledge of the recent fauna and flora. There is, to be sure, more or
less intermingling of the species. The myriapods, so far as they have been
found, are also localized. Mr. Carr found 3 within a space of a few feet,
but again these are found widely scattered. The exposures at the "upper
beds" are about a quarter of a mile long. They disappear under a heavy
ledge of sandy limestone.

At the "lower beds" (plate 1, fig. 6), those further down the creek,
conditions are quite different from those just described, although of the
same horizon: the banks of the creek are higher and almost perpendicular,
so that the chances of collection from the shales are fewer. The bed of
the creek, however, is wider and there are more nodules washed out. The
most abundant fossil at this place is _Neuropteris_. The nodules at the
upper end of the exposure are all, almost without exception, barren of
fossils. The exposures here are of about the same extent as the "upper
beds," though the species are not so varied. Judging from the collections
made while there, Arthropoda are more abundant at the "lower beds."

Bradley (Geol. Surv. Illinois, IV, 196, 1870) mentions the occurrence
of these nodules at or near Morris. Other than these places the nodules
have been thrown out of a coal mine near Braidwood, Illinois. Doubtless
close search would reveal other localities where the shale is cut through
in mining. The beds at both places are slightly folded. This is true
especially of the "upper beds," where a conspicuous fold caused the beds
to disappear in the bed of the creek and to reappear farther down stream.
This is directly across the large "ox-bow" bend of the creek.

The beds at Mazon Creek were first explored in 1857 by Mr. Joseph Evans,
who sent his specimens to Berlin, Germany, where they excited great
interest. It was he who collected the type specimen of _Amphibamus
grandiceps_ Cope. Since the time of Mr. Evans many have collected at Mazon
Creek, and without doubt the fossil-bearing nodules from this locality are
more widely scattered in the museums of the world than are organic remains
from any other one horizon.

So far as we know there was no upland vertebrate life at that time. The
forms at present known were confined to the water or the margins of the
water. The absence of knowledge of upland and terrestrial deposits of
this time doubtless accounts for the absence of known vertebrates. It is,
however, especially interesting to speculate on the ancestral types of the
land vertebrates, and it must be admitted that the Coal Measures Amphibia
as at present known throw the ancestry of land-living vertebrates far back
into geological time.

(_m_) The Cannelton slates of Beaver County, Pennsylvania, have furnished
3 species of Amphibia and fragments of other species are represented in
the U. S. National Museum (462). The species so far known are: _Tuditanus
minimus_ Moodie, _Erpetosaurus sculptilis_ Moodie, _Erpetosaurus minutus_
Moodie.

They are the first evidence of the occurrence of amphibian remains in
these deposits. The Cannelton specimens are found in a thin stratum of
slate which forms part of the Middle Cannelton Coal. The Cannelton slate,
in which the fossils occur, forms the roof of the Middle Kittanning Coal,
which is only 20 to 30 feet above the Lower Kittanning bed (I. C. White),
so it becomes evident that the deposition of the Cannelton slates was at
only a slightly later period than that of the shales in which the Mazon
Creek nodules occur, since the Mazon Creek shales form the roof of the
Morris, which "is probably somewhat lower than the Lower Kittanning of
Pennsylvania." From the Cannelton slates are known the remains of plants,
insects, crustacea, especially "Eurypterids found in shale immediately
below the Darlington (Upper Kittanning) Cannel Coal, near Cannelton,
Darlington Township, Beaver County, Pennsylvania, Horizon, Allegheny River
Series" (Hall, 1884). In these shales occur also, fishes and the 3 species
of amphibians referred to above. The Amphibia known from this region are
small, the largest of them not exceeding 6 inches in length.

[Illustration: Fig. 4. Portion of "West Virginia-Ohio-Pennsylvania,
Wellsville Quadrangle" of the U.S. Geological Survey, to show topography
and situation of Linton coal mines. Some fossil amphibians doubtless came
from across the line in Columbiana County.]

(_n_) The Linton, Ohio, beds outcropped near Linton post-office, which
was formerly located at the mouth of Yellow Creek, a few hundred yards
from the present station, Yellow Creek, Salem Township, Jefferson County,
in the valley of Yellow Creek, near the Ohio River, and thus near the
Pennsylvania state line.

In regard to the exact location of the town of Linton, which has long
since been abandoned, I quote from a letter from Dr. Louis Hussakof, who
visited the locality:

  "The locality appears to have been known as Yellow Creek for many
  years past. That is the name used in the Geological Map of Ohio
  published by Orton in 1888 and which was based on the earlier maps
  of Newberry (1869 and 1879). When I visited the place in 1905, and
  asked for Linton (which I had not been able to locate on any map then
  available to me), hardly anyone knew of such a locality. Only one old
  man in Steubenville, Ohio, recalled that Yellow Creek was identical
  with Linton.

  "Yellow Creek is not a village, but only a R. R. station (on the
  Pennsylvania R. R.), and marks a spot where once was an active
  and prosperous mine. Probably at a former day there was a small
  post-office somewhere in the neighborhood known as Linton. I did not
  take any photographs, as I was not certain of the spot, or the mine,
  from which the fossils had come. There are some cement mines within a
  few minutes' walk of the station, but no coal appears to be mined at
  present at Yellow Creek. 'Smith's Pit,' the coal mine best remembered
  by the younger men, is not worked.

  "Now as to the question whether some of the Amphibia might have come
  from localities in Columbiana County. I believe it very probable that
  they did. I walked along the road from Yellow Creek (Jefferson County)
  to Wellsville (Columbiana County), a distance of about 2 or 2.5 miles,
  and the country seemed quite the same. Everywhere one sees outcrops
  of coal in the cuts along the road. Furthermore, I inclose a copy of
  a page in an old notebook of Professor Newberry from which you will
  see that Coal Measure fossil localities were known not only at Yellow
  Creek, but also from near Wellsville. There can be hardly a doubt that
  most of the specimens you have are from Yellow Creek; and quite a
  number are those collected by Sam Huston."

Newberry says, in regard to the fauna of the Linton Coal:

  "The Linton locality is especially interesting and instructive. It
  has already (1889) yielded more than 20 species of fishes and nearly
  40 species of aquatic amphibians, all inhabitants of the same body
  of water. These were found in a thin stratum of cannel which, over
  a limited area, underlies a thick bed of cubical coal (No. 6 of the
  Ohio reports), of which the place is near the top of the Lower Coal
  Measures. At Linton, ... we have evidence that the great marsh in
  which the peat accumulated that formed coal No. 6 was for a time a
  lake or a lagoon, inhabited by the fishes and amphibians to which I
  have referred.... Many of the fishes and the amphibians were highly
  carnivorous and powerful, as we learn from their teeth and coprolites.
  The largest of the amphibians must have been 8 or 10 feet in length,
  having strong jaws, set with numerous lancet-shaped teeth an inch
  or more in length.... After a sufficient time had elapsed for many
  generations of fishes and aquatic salamanders to live and die, the
  lake was filled by the extension of its peaty shores into it just as
  so many lakelets are filled and obliterated at the present time and
  afterward over the cannel was formed a mass of peat, which has now
  become a stratum of cubical coal 7 feet in thickness.

  "In the Linton cannel are buried fragments or entire individuals of
  all the inhabitants of this body of water which had hard parts, bones,
  scales, spines, or teeth, capable of preservation. Hence we get a
  locally complete picture of the life of the Carboniferous age, and we
  find it to be unexpectedly rich and varied. In that age fishes and
  amphibians were the highest forms of animal life, and the amphibians
  were comparatively newcomers on the earth's surface. Yet they had
  multiplied and differentiated until this little pool contained
  millions of them, varying in length from 6 inches to 10 feet and
  curiously diversified in their forms, their scales, and spines, and in
  the ornamentation of their enamel-covered heads" (498).

  "To the paleontologist there are few places in the world more
  interesting than the Diamond mine, at Linton, since here we get such
  a view of the life of the Carboniferous age as is afforded almost
  nowhere else, and of the great numbers of species found there, not
  more than three or four have been met with elsewhere" (497).

On page 18 is a list of the Amphibia which are thus far described from the
Linton deposits. They all belong, so far as known, to the Microsauria, the
reference of any of the species to other orders being doubtful. The larger
Amphibia seem to be indicated by a large rib which resembles very much
that described by Huxley in 1863 for _Anthracosaurus_.

Amphibia from the Linton Beds (51 SPECIES).

  _Brachydectes newberryi_ Cope. Fragment of a skull.
  _Cercariomorphus parvisquamis_ Cope. Impression of body.
  _Cocytinus gyrinoides_ Cope. A skull and anterior dorsal vertebræ.
  _Ctenerpeton alveolatum_ Cope. Large portion of skeleton, no skull.
  _Diceratosaurus lævis_ Moodie. Complete skull.
  _Diceratosaurus punctolineatus_ Cope. Anterior vertebræ, part of skull,
     with ribs and portion of ventral armature.
  _Diceratosaurus robustus_ Moodie. Incomplete cranium.
  _Eoserpeton (Ceraterpeton) tenuicorne_ Cope. Incomplete skull.
  _Erpetosaurus acutirostris_ Moodie. Complete skull.
  _Erpetosaurus obtusus_ Cope. Incomplete skull.
  _Erpetosaurus radiatus_ Cope. Incomplete skull.
  _Erpetosaurus tabulatus_ Cope. Incomplete skull, with clavicles.
  _Erpetosaurus tuberculatus_ Moodie. Incomplete skull.
  _Eurythorax sublævis_ Cope. A single interclavicle. (Operculum of lung
     fish, _Sagenodus_.)
  _Hyphasma lævis_ Cope. Incomplete skull and anterior vertebræ.
  _Ichthycanthus ohiensis_ Cope. Portion of dorsal region.
  _Ichthycanthus platypus_ Cope. Posterior portion of body.
  _Leptophractus dentatus_ Moodie. Mandible.
  _Leptophractus lineolatus_ Cope. Incomplete skull.
  _Leptophractus obsoletus_ Cope. Portions of skull.
  _Macrerpeton deani_ Moodie. Mandible and part of skull.
  _Macrerpeton huxleyi_ Cope. Part of cranium.
  _Molgophis brevicostatus_ Cope. Part of vertebral column with ribs.
  _Molgophis macrurus_ Cope. Vertebral column.
  _Molgophis wheatleyi_ Cope. Part of skull with 25 vertebræ.
  _Odonterpeton triangularis_ Moodie. Skull and anterior part of body.
  _Œstocephalus rectidens_ Cope. Part of mandible.
  _Œstocephalus remex_ Cope. Skull and anterior part of body.
  _Pelion lyelli_ Wyman. Cranium, fore part of body, hind limb.
  _Phlegethontia linearis_ Cope. Skull and anterior part of body.
  _Phlegethontia serpens_ Cope. Series of 22 dorsal vertebræ.
  _Pleuroptyx clavatus_ Cope. Part of vertebral column and limbs.
  _Ptyonius marshii_ Cope. Part of skull and anterior vertebræ.
  _Ptyonius nummifer_ Cope. Skull and greater part of vertebral column.
  _Ptyonius pectinatus_ Cope. Many specimens, some nearly perfect.
  _Ptyonius serrula_ Cope. Nearly complete skeleton.
  _Ptyonius vinchellianus_ Cope. Skull and anterior vertebræ.
  _Saurerpeton latithorax_ Cope. Skull and fore part of body.
  _Sauropleura digitata_ Cope. Greater part of body minus skull.
  _Sauropleura (Anisodexis) enchodus_ Cope. Part of jaw.
  _Sauropleura foveata_ Cope. A single interclavicle with impression.
  _Sauropleura longidentata_ Moodie. Incomplete skull with mandible.
  _Sauropleura newberryi_ Cope. Two incomplete skulls with vertebræ.
  _Sauropleura pauciradiata_ Cope. Elements of a pectoral arch.
  _Sauropleura scutellata_ Newberry. Imperfect skeleton.
  _Stegops divaricata_ Cope. Nearly complete skull.
  _Thyrsidium fasciculare_ Cope. Dorsal vertebræ.
  _Tuditanus brevirostris_ Cope. Skull and anterior vertebræ.
  _Tuditanus longipes_ Cope. Part of vertebral column with limbs.
  _Tuditanus punctulatus_ Cope. Skull and anterior part of body.
  _Tuditanus walcotti_ Moodie. Skull and portions of body.

Besides the above-listed species there are others indicated by fragments
too poorly preserved to be worthy of specific designation. The Linton
Amphibia are all apparently confined exclusively to that locality. Species
from the Cannelton slates have been assigned, however, to genera which
occur at Linton, _i.e._, _Erpetosaurus_ and _Tuditanus_. This reference
may be due to lack of knowledge, as the forms are insufficiently known. A
single Linton species has been assigned to _Ichthyerpeton_, a genus known
otherwise only from the Coal Measures of Kilkenny, Ireland. Cope referred
species from Linton to the genus _Ceraterpeton_ of Huxley, from Kilkenny,
Ireland, but Jaekel (347) and the writer (462) have shown that the
species were incorrectly assigned to the genus _Ceraterpeton_, and that
in fact they represent widely distinct genera. A single species has been
identified by Eastman from the Des Moines limestone of Iowa as identical
with one from Linton, _Pleuroptyx clavatus_ Cope. The Linton fauna is
distinct from that of the Mazon Creek beds, and also from that of South
Joggins, Nova Scotia.

(_o_) The deposits in Nova Scotia have been correlated with the Coal
Measures strata of the United States (Bell, Summ. Rpt. Geol. Surv. Canada,
1912, 1914, 360-371). They are very near the same age as the Linton beds
and come in near the base of the Allegheny River series. The exposures
are at the South Joggins, along the sea-coast. Here in strata of clay
interstratified with coal are found the erect stumps of the Sigillariæ,
and it was in the rock within these stumps that Lyell and Dawson, in 1853,
discovered the remains of the amphibians which they termed "reptiles."

  "The bones of Dendrerpeton hitherto found, as well as those of the
  smaller species, have been obtained from the interior of erect
  Sigillariæ, and all of those in one of the many beds which, at the
  Joggins, contain such remains. The thick cellular inner bark of the
  Sigillaria was very perishable; the slender woody axis was somewhat
  more durable; but near the surface of the stem, there was a layer of
  elongated cells, or bast tissue of considerable durability, and the
  outer bark was exceedingly dense and indestructible. Hence an erect
  tree, partly imbedded in sediment, and subjected to the influence of
  the weather, became a hollow shell of bark. When they remained open
  for a considerable time, they would constitute pitfalls into which
  animals walking on the surface might be precipitated. When the surface
  was inundated all such remains would be covered and imbedded in the
  sediment. These seem to have been the precise conditions of the bed
  which afforded these remains." (Dawson, 223, 1894.)

Fifteen species have been described from the Joggins deposits. Two are
known from the Albion mines, south Nova Scotia, where were obtained the
remains of _Baphetes planiceps_ Owen and _B. minor_ Dawson.

The following 17 species of Amphibia are known from the Carboniferous of
Canada:

  _Amblyodon problematicum_ Dawson. Teeth and fragments.
  _Baphetes minor_ Dawson. An incomplete mandible.
  _Baphetes planiceps_ Owen. An incomplete cranium from Albion.
  _Dendrerpeton acadianum_ Owen. A jaw, limb bones, and fragments.
  _Dendrerpeton oweni_ Dawson. Phalangeal bone and fragments.
  _Eosaurus acadianus_ Marsh. Two dorsal vertebræ.
  _Fritschia curtidentata_ Dawson. A mandible, vertebræ, ribs.
  _Hylerpeton dawsoni_ Owen. Mandible, teeth and incomplete maxilla.
  _Hylerpeton intermedium_ Dawson. Mandible and portions of skull.
  _Hylerpeton longidentatum_ Dawson. Fragments of mandible and skull.
  _Hylonomus latidens_ Dawson. Mandible and teeth.
  _Hylonomus lyelli_ Dawson. Incomplete skeleton and part of skull.
  _Hylonomus multidens_ Dawson. Fragments of skull.
  _Hylonomus wymani_ Dawson. Mandible and vertebræ.
  _Platystegos loricatum_ Dawson. Incomplete skull, vertebræ.
  _Smilerpeton aciedentatum_ Dawson. Teeth, ribs, fragments.
  _Sparodus_ sp. indet. Teeth, scales.

(_p_) All the remains representing the above species were collected by
Sir J. William Dawson at the South Joggins and at the mines of Albion,
with the exception of _Eosaurus_, which was collected by O. C. Marsh.
The collections of Dawson are now in the Peter Redpath Museum of McGill
University in Montreal and in the British Museum of Natural History at
South Kensington, London. The history of the discovery of the deposits and
their amphibian fossils at the South Joggins is so interesting that it
was thought worth while to reproduce in large part Dawson's paper "On the
Mode of Occurrence of Remains of Land Animals in Erect Trees at the South
Joggins, Nova Scotia," published in 1891 in the Transactions of the Royal
Society of Canada, section IV, p. 127:

  "The remarkable section of coal-formation rocks at the South Joggins,
  in Cumberland County, has long been known as one of the most
  instructive in the world; exhibiting as it does a thickness of 5,000
  feet of strata of coal-formation in a cliff of considerable height,
  kept clean by the tides and waves, and in the reefs extending from
  this to the shore, which at low tide expose the beds very perfectly.
  It was first described in detail by the late Sir W. E. Logan (Report
  Geol. Surv. Canada, 1844), and afterwards the middle portion of it
  was still more detailed by the author (Dawson), more especially in
  connection with the fossil remains characteristic of the several beds
  and the vegetable constituents and accompaniments of the numerous
  seams of coal (Jour. Geol. Soc. Lond., X, p. 1, 1853). It was on
  occasion of a visit of the author in company with Sir Charles Lyell,
  and in the pursuit of these investigations, that one of the most
  remarkable features of the section was disclosed in 1851. This is
  the occurrence, in the trunks of certain trees imbedded in an erect
  position in the sandstones of Coal-mine Point, of remains of small
  reptiles, which with one exception, a specimen from the Pictou
  coal-fields, were the first ever discovered in the Carboniferous rocks
  of the American continent, and are still (1891) the most perfect
  examples known of a most interesting family of coal-formation animals,
  intermediate in some respects between reptiles proper and batrachians,
  and known as Microsauria. With these were found the first-known
  Carboniferous land snails and millipedes. Very complete collections of
  these remains have been placed by the author with his other specimens
  in the Peter Redpath Museum and in the British Museum.

  "A forest or grove of the large ribbed trees known as _Sigillariæ_ was
  either submerged by subsidence or, growing on low ground, was invaded
  with the muddy waters of an inundation, or successive inundations,
  so that the trunks were buried to the depth of several feet. The
  projecting tops having been removed by subaerial decay, the buried
  stumps became hollow, while their hard outer bark remained intact.
  They thus became hollow cylinders in a vertical position and open
  at the top. The surface having then become dry land, covered with
  vegetation, was haunted by small quadrupeds and other land animals,
  which from time to time fell into the open holes, in some cases nine
  feet deep, and could not extricate themselves. On their death, and
  the decomposition of their soft parts, their bones and other hard
  portions remained in the bottom of the tree intermixed with any
  vegetable debris or soil washed in by rain, and which formed thin
  layers separating successive animal deposits from each other. Finally,
  the area was again submerged or overflowed by water, bearing sand
  and mud. The hollow trees were filled to the top and their animal
  contents thus sealed up. At length the material filling the trees was
  by pressure and the access of cementing matter hardened to stone, not
  infrequently harder than that of the contained beds, and the whole
  being tilted to an angle of 20°, and elevated into land exposed to
  the action of the tide and waves, these singular coffins present
  themselves as stony cylinders projecting from the cliff or reef, and
  can be extracted and their contents studied. The singular combination
  of accidents above detailed was, of course, of very rare occurrence,
  and, in point of fact, we know only one set of beds at the South
  Joggins in which such remains so preserved occur; nor is there, so
  far as I am aware, any other known instance elsewhere. Even in the
  beds in question, only a portion of the trees, about 15 out of 30,
  have afforded animal remains. We have, however, thus been enabled to
  obtain specimens of a number of species which would probably otherwise
  have been unknown, being less likely than others to be preserved in
  properly aqueous deposits. Such discoveries on the one hand impress
  us with the imperfection of the geological record; on the other, they
  show us the singular provisions which have been made in the course of
  geological time for preserving the relics of the ancient world, and
  which await the industry and skill of collectors to disclose their
  hidden treasures.

  "There is evidence in coprolitic matter on one of the surfaces within
  the trunks, and also in certain trails on these surfaces, that some of
  the imprisoned animals lived for a time in their subterranean prisons;
  that they crept around their walls in search of a way of escape, and
  that the larger animals fed on smaller species entrapped along with
  them."

After the discovery of these entombed amphibians Sir William Dawson was
given a grant of £50 from the Government Fund by the council of the
Royal Society of London, to aid in the extraction of these trees and the
collection of their contents. The trees were carefully taken out and
their contents examined; the portions containing the animal remains were
carefully boxed to be taken to Montreal for final cleaning and study.
Erosion goes on rapidly at the South Joggins, but no one has paid any
attention to the occurrence of Amphibia along the coast of Nova Scotia
within recent years.

[Illustration: Fig. 5. Dawson's tree No. 13 at the South Joggins, Nova
Scotia. Upper part, _in situ_, in the reef after it had been exposed by
blasting. (After Dawson, based on a photograph.)]

(_q_) A deposit which will be of undoubted interest in connection with
the occurrence of Amphibia in the Coal Measures is that which outcrops
along the banks of Rock Creek in the South western part of Douglas County,
Kansas, in Marion Township (Township 14 south, Range 18 east, SW. and SE.
quarters of section 7), about 2 miles from the now-abandoned post-office
of Twin Mounds, so called from the two flat-topped, elongated mounds of
Oread limestone to the west of the town.

The interest in these beds is not due to the discovery of Amphibia in
them, but the possibilities of such discoveries. This is indicated by the
occurrence of fossils, in nodules similar to those obtained from Mazon
Creek, which are identical generically, nd in most cases specifically,
with the Mazon Creek animals and plants.

The fossils so far collected from this interesting locality are:

Insecta (Identified by Dr. E. H. Sellards).
    _Spiloblattina maledicta_ (Scudder). The basal half of a front wing.
    _Etoblattina_ sp. The hind wing of a cockroach.

Arachnida.
    _Anthrocomartus_. Impression of the body.
    _Prestwichia danæ_ M. & W. Nearly complete specimen.

Crustacea.
    _Acanthotelson stimpsoni_ M. & W. Three nearly complete individuals.

Plants (Identified by Mr. J. C. Carr, of Morris, Ill.).
    _Pecopteris_ sp.
    _Sagittaria reticulata_ Lesquereux.
    _Annularia longifolia_ Lesquereux.
    _Annularia inflata_ Lesquereux.
    _Pecopteris villosa_ Brongniart.
    _Neuropteris decipiens_ Lesquereux.
    _Pecopteris serpulifolia_ Lesquereux. By far the most abundant plant
      is _Pecopteris_.

The fossils occur in definite strata of nodules immediately above a
10-inch coal seam which is worked for local consumption. The coal lies
near the base of the exposure in the more western portion of the outcrop,
but it is raised by an anticlinal fold to near the top of the creek-banks
by the bridge across Rock Creek, along the banks of which the shales are
exposed. Nodules containing fossils are found most abundantly at the
western exposure on the McKinzie place, only a few having been found near
the bridge.

Below the coal-seam, nodules of various shapes and sizes occur, but they
seldom contain fossils and never good ones. Occasionally, as at Mazon
Creek, fragments of plants adhere to the outside of the incrusting shale.
A single nodule may have adhering to it fragments of 4 genera of plants.
The fossiliferous nodules all occur above the coal and are most prolific
and abundant immediately above the seam, within the first 10 inches. In
the same stratum of shale with the nodules are found abundant impressions
of plants in the shale, often perfect fronds being uncovered. (See, in
this connection, Twenhofel and Dunbar, 1914, "Nodules with Fishes from the
Coal Measures of Kansas," Amer. Journ. Sci., XXXVIII, pp. 157-163.)

G. F. Matthew (408-413) has described numerous genera and species of
footprints, presumably amphibian, from the Carboniferous of Canada. The
impressions indicate small creatures for the most part. Other imprints
have been described by Logan, Dawson, Lyell, Marsh, Mudge, and Lea. Since
the present work is intended largely for a morphological review, only
passing notice can be given to the _ichnites_. The literature on the
"Ichnites" has been brought together in Hay's "Bibliography and Catalogue
of Fossil Vertebrata of North America," pp. 538-553. References since the
publication of Hay's catalogue (317) will be found in the bibliography at
the end of this work. Footprints are of interest in that they are the only
evidence we have of the occurrence of land vertebrates in the Devonian and
Mississippian of North America.



CHAPTER IV.

THE MORPHOLOGY OF THE COAL MEASURES AMPHIBIA.


The anatomy of the Coal Measures Amphibia presents many primitive types
of structure. Their organization represents a stage passed through
in the ontogeny of higher vertebrates. The animals are similar in a
general way, yet so diverse are the modifications which they have
suffered under different environmental conditions, that close scrutiny
is needed to discern the exact relationship of the forms. Our knowledge
of this relationship is based on the structures preserved, which are
largely skeletal, since little is known of the soft anatomy (471) of the
air-breathing vertebrates of the Coal Measures. The pubis is ossified in
the Paleozoic Amphibia later than the ischium and ilium; the carpus and
tarsus are cartilaginous; the vertebræ consist of a pleurocentrum and two
neurocentra, thus paralleling conditions in modern mammalian embryos.

[Illustration: Fig. 6.--Generalized figure of dorsum of an early amphibian
skull to show position of elements and terminology adopted in this work.
The outline is based on that of _Eryops_, but is in no way intended to
indicate that form.

_a. com_, anterior commissure of lateral-line canals; _com_, commissural
communication between infra- and supra-orbital lateral-line canals; _fr_,
frontal; _inf_, interfrontal; _inn_, internasal; _info_, infraorbital
lateral-line canal; _it_, intertemporal; _jl_, jugal lateral-line canal;
_j_, jugal; _lar_, lacrimal; _mx_, maxilla; _n_, nasal; _oc_, occiput;
_occ_, occipital cross-commissure of the lateral-line system; _or_,
orbit; _par_, parietal; _pof_, postfrontal; _pmx_, premaxilla; _pf_,
prefrontal; _po_, postorbital; _pp_, postparietal; _g_, quadrate; _qj_,
quadratojugal; _spo_, supraorbital lateral-line canal; _sq_, squamosal;
_spt_, supratemporal; _t_, temporal lateral-line canal; _tab_, tabulare.]

(_a_) The skull of the Coal Measures Amphibia has (fig. 6) essentially
the same structure in the different groups. It is largely formed of
bones of intramembranous origin, representing the _face_ bones of the
mammalian skull. The skull in life was doubtless a _chondrocranium_ with
the membrane bones laid down upon the cartilaginous box containing the
sense-organs, as in the sturgeon (_Acipenser_), where the surface bones of
the face were probably originally scales, which later became consolidated
into large bony scutes. The membrane bones of the early Amphibia may have
been originally derived from scales, but at present nothing is known of
this origin; doubtless the elements had an intramembranous origin in the
ancestors of the group. Judging from Credner's studies on the series
of specimens of _Branchiosaurus amblystomus_ Credner (187), the skull
bones do not ossify completely until relatively late in the life of the
individual. The skull in the youngest individual figured by Credner
(_op. cit._, Taf. XVI, fig. 1) seems to be largely cartilaginous, with
beginnings of separation into the skeletal elements. The manner and
time of development and ossification of the skull seems to proceed much
as it does in modern amphibians. The condition found in the skull of
_Cryptobranchus allegheniensis_ or _Necturus maculosus_ will represent
pretty accurately the condition of most of the Coal Measures Amphibia. The
face bones in certain forms were sculptured and cut by lateral-line canals.

A median suture divides the skull into two equal regions dorsally. On
the sides of this median suture lie pairs of elements which are common
to all higher vertebrates. These elements are: the premaxillæ, nasals,
frontals, parietals, and post-parietals. All of these elements vary
somewhat in shape and slightly in arrangement, but always occupy the same
relative positions. To the side of these elements lie the prefrontal, the
postfrontal, the supratemporal, the squamosal, and tabulare, and occupying
the margin of the skull are the maxilla, the jugal, the quadratojugal, and
possibly the quadrate in a few forms. The parietal foramen occurs usually
within the parietal bone, but its position is subject to slight variations
and it may occur on the suture between the frontal and the parietal, or
even far posterior near the postparietal. The nostrils often lie well
forward and are included by the premaxillæ, nasals, and prefrontals. The
orbit is usually well posterior, but it may occur far forward. It is
bounded by the prefrontal, the frontal, the postfrontal, the post-orbital,
and the jugal. Sometimes the lacrimal is present and has been clearly
identified on the anterior margin of the orbit in a few cases.

(_b_) _Sclerotic plates_ often occur within the orbits, and are not
confined to any particular group, though they are quite constant among
the Branchiosauria. They are usually delicate, thin, broad plates which
evidently overlap and operate as in modern animals. The number varies, as
many as 30 occurring within the orbit of one branchiosaur. Between the
margin of the orbit and the sclerotic plates there often occur, in the
Branchiosauria (186) particularly, small scale-like particles which were
doubtless embedded in the heavy skin above the orbit during life.

(_c_) The _palate_ of the skull is very incompletely known, being
indicated in a very few cases. These specimens, however, show that
the characters of the palate were quite similar, if not identical, in
essential respects with the palate among the European species of the same
or slightly later time.

A large cultriform parasphenoid occupies the posterior portion of the
palate, on either side of which in some species lies the posterior
palatine foramen. On the sides of the anterior prolongation of the
parasphenoid lie the vomers (186), membranous bones often bearing minute
tubercular teeth, apparently adapted for crushing. The vomers and the
maxillæ, with sometimes the palatine, surround the anterior palatine
foramen, which is almost always present; sometimes, however, quite small.
The transverse or ectopterygoid unites the pterygoid, a broad plate of
thin bone, with the maxilla and jugal.

(_d_) The teeth of the Coal Measures Amphibia (194) are remarkably similar
in the various forms. They are always slender, pleurodont denticles
arranged in a single row on the jaws or as tubercular eruptions on the
palate bones, with a large pulp-cavity and the enamel often striated. The
food of the creatures must have been small Crustacea, worms, insects, and
succulent vegetation, such as is the food of the modern Amphibia.

(_e_) The _occiput_ is formed of partially ossified (465) ex- and
basi-occipitals, though these elements are never firmly united by ossific
union. Often a pair of condyles occur, one on either exoccipital. The
occiput was usually, however, cartilaginous and no trace of its structure
is preserved.

(_f_) The _mandible_ is usually as long as the skull and is slender. It
is composed of 6 elements so far as known (465); these are the articular,
the surangular, the angular, the coronoid, the dentary, and the splenial.
Other elements may be present, but the anatomy of this portion of the
animals is not very completely known. The bones are sculptured and cut by
lateral-line canals (458) in a few forms. Whether the articular operated
on an osseous or cartilaginous quadrate is unknown, though certain
specimens seem to indicate an osseous condition for that element. The
anterior symphysis was doubtless ligamentous, the halves always separating
before fossilization. The dentary always bears a single row of pleurodont
teeth, which may vary greatly in size and number.

(_g_) The _hyoid apparatus_ is well preserved in a few forms (123).
Doubtless it was present in all of them, though it has seldom been
preserved. The condition of the hyobranchial apparatus in _Cocytinus
gyrinoides_ (text-fig. 16) from the Coal Measures of Linton, Ohio,
seems to indicate that the species was a perennibranchiate salamander
(123). It is well known from the studies of Credner that the European
Branchiosauria, in the young, possessed external branchiæ (187) supported
by lateral basibranchials. The gill-arches seem to have been slightly
calcified or ossified in a few cases, and they supported denticle-like
projections which bore the gill-filaments. When the Branchiosauria had
attained a length of 100 mm. or more they lost their gills (187). This
change was accompanied by the reduction of the tail, expansion of the
pelvis, and increase in ossification of the skull and skeletal elements.
Gills have not yet been detected among the American Branchiosauria.

(_h_) The _eye_ in a few species had a large amount of black pigment,
as indicated by the blackening of the stone in the Mazon Creek nodules.
Professor Cope (107) thought that this would indicate a nocturnal and
crepuscular habit for these vertebrates, since the _pigmentum nigrum_ of
the choroid is largely developed. Other than this suggestion nothing is
known of the soft parts of the head.

(_i_) The _alimentary canal_ (text-fig. 7) is beautifully preserved
as a cast in three specimens of the American branchiosaur species
_Eumicrerpeton parvum_ Moodie (471) from the Mazon Creek beds. The nodules
which contain these interesting little fossils measure less than 3 inches
in long diameter. The fossil salamanders, about 30 mm. in length, are
preserved on their backs and occur as nearly as is possible in the center
of the nodule.

If it were not for the fact that the œsophagus became loosened and dropped
from its place shortly after death, the alimentary canal would be in
place and would immediately recall a freshly dissected specimen of a
recent salamander. The anterior end of the œsophagus lies obliquely across
the chest region with its tip pointing slightly downward. The length
of the œsophagus proper, in one specimen, is only about 3 mm. As it is
preserved, the œsophagus lies in a semi-sigmoid curve with the convexity
anterior, and enters the cardiac portion of the stomach by a gradual
constriction. The stomach is clearly preserved as a distinct sac-like
organ with two lobes which correspond to the cardiac and pyloric limbs.
It measures about 7 mm. in length by 2 mm. in its greatest diameter.
The muscular constriction which divides the organ into pyloric and
cardiac divisions occurs at a distance of 4 mm. from the upper end. The
pylorus is designated by a rather pronounced constriction which may be
partly accidental, although it recalls the pylorus of modern frogs. From
this constriction, which lies on the left side of the fossil, as it is
preserved, the duodenal portion of the intestine makes a straight course
posteriorly to near the anal region, where it takes a sharp bend and
curves back to run parallel with itself for the distance of 4 mm. In its
upward course the intestine enlarges, and practically the same enlargement
continues throughout the remainder of the course to the anus. At a
distance of 1 mm. from the anal end, the rectum dilates probably 0.125
mm. to form the cloaca. After the intestine has continued its parallel
course for the 4 mm., as above stated, it turns abruptly to the right for
a distance of 2 mm. It then runs posteriorly for a short distance, then
bends back and under itself to again make a double sigmoid curve, when at
a distance of 6 mm. from the anus it assumes a straight course, which it
continues to the end.

[Illustration: Fig. 7.--Alimentary canal of Coal Measures salamander as
illustrated by the smaller specimen of _Eumicrerpeton parvum_ Moodie, from
the Mazon Creek shales. × 3. Original in Yale University Museum. _a_,
anus; _dd_, duodenum; _in_, intestine; _l_, impression of liver(?); _oes_,
œsophagus; _st_, stomach.]

The anus lies at a level which is approximately that of the lower end
of the femur, which is preserved as an impression on the left side of
the fossil, thus agreeing in its position with that found in modern
Caudata. Lying inside the curve of the stomach and partly inclosed by the
œsophagus is a smooth area which may possibly represent the impression
of some of the accessory digestive glands, such as the liver. Occurring
in this smooth area are numerous fine lines which possibly represent the
impressions of blood-vessels; but they are so imperfectly preserved that
one can not be sure.

Representatives of several genera of the modern Caudata have been
dissected in order to make a direct comparison of the fossil alimentary
canal with that of the recent forms. The alimentary tract of _Desmognathus
fuscus_ Raf. from the vicinity of Ithaca, New York, resembles in a
marked degree that of the fossil form. The nearest approach to the
condition there represented is found, however, in an immature branchiate
individual, some 47 mm. in length, of _Diemyctylits torosus_ Esch., from
a fresh-water pond on Orcas Island in Puget Sound. The presence of this
species on the island is very suggestive. It is of extreme interest, too,
that the condition represented in the alimentary tract of the fossil
branchiosaurs should resemble so closely that of an immature rather than a
mature form.

(_j_) The vertebral column is clearly and readily separable into cervical,
dorsal, sacral, and caudal regions. The neck is always short, with from
5 to 10 vertebræ, cervical ribs often present. The dorsal region is not
long, but varies from 20 to 30 in the constituent vertebræ. There is a
single sacral vertebra not always to be readily distinguished from those
of the dorsal and anterior caudal series. The tail may be very short
or extremely long, with neural and hæmal spines elongate and flattened
into an oar-like appendage. The distal caudals are in some species
cartilaginous, apparently always so in the Branchiosauria.

(_k_) The _atlas_ and _axis_ are unknown among the American specimens, but
we are able to infer from the structure of the other vertebræ what this
must have been; and our inferences are partly confirmed by the conditions
existing in the European forms (187). The atlas, apparently, consisted of
a pair of neurocentral plates which are partly ossified, partly embedded
in cartilage, judging from the edges of the plates which have been
preserved. The centrum seems not to have been present in the atlas, or if
present it was only very slightly developed and quite free from the neural
pieces and largely embedded in cartilage. A fairly accurate picture of the
condition of the _atlas_ and _axis_ may be seen on examining a cow, pig,
or chick embryo (378) in the early stages of vertebral development, which
has been cleared by the Schultze method (Amer. Journ. Anat., VII, No. 4,
1908).

(_l_) The _dorsal vertebræ_, as well as those of the other series, present
a primitive character (fig. 8) in the persistence of the notochord
(540). Among the Branchiosauria the notochord was not at all or but
slightly constricted intravertebrally, but among the Microsauria it was
constricted so far that the notochordal remnants in each centrum resemble
an hour-glass.

The structure of the vertebræ among American forms agrees fully with that
outlined by Credner, Fritsch, and others for the European species. The
details of structure are so fully given by Zittel (642, pp. 346-353) and
by Schwarz (540, 541) that it will not be necessary to state more here
as to their structure, since there is nothing new to add concerning the
American species.

The temnospondylous vertebra of the same nature and type as exhibited by
the Permian forms has its representatives (94, 478) in the Coal Measures.
_Spondylerpeton spinatum_ Moodie (478) (plate 4, figs. 1, 2) and _Eryops_
sp. (plate 18, fig. 2) indicate the embolomerous and rachitomous types
of vertebral structure. The occurrence of these widely different types
of vertebral structure indicates a long history for the group prior to
the Coal Measures. This history is further indicated by footprints in the
Mississippian and Devonian of this continent.

[Illustration: Fig. 8.--Vertebræ and ribs of Amphibia from the Coal
Measures of Linton, Ohio. Originals in Geol. Inst. Berlin. (All after
Schwarz.)

  A. Caudal vertebra of _Œstocephalus remex_ Cope. Lateral view. × 4.

  B. Caudal vertebra of _Ptyonius vinchellianus_ (?) Cope. Lateral
       view. × 6.

  C. Dorsal vertebra of _Ptyonius pectinatus_ Cope. Lateral view. × 9.

  D. Notochordal cones and spinal canal of _Thyrsidium fasciculare_
       Cope. × 3.

  E. Rib of Molgophis sp. Cope. × 1.75. _c_=capitulum; _t_=tuberculum.

  F. Vertebra of _Molgophis_ sp. Cope, from ventral side. × 2.

  G. Dorsal vertebra of _Ptyonius pectinatus_ Cope. From above. × 8.

  H. Dorsal vertebra of _Thyrsidium fasciculare_ Cope, from below. ×
       2.5.

  I. Vertebra of _Phlegethontia linearis_ Cope, from above. × 5.5

  J. Rib of _Œstocephalus remex_ Cope, from posterior dorsal region. ×
       5.

  K. Dorsal vertebra of _Thyrsidium fasciculare_ Cope, from above. ×
       1.5

  L. Anterior dorsal vertebra (cervical?) of _Thyrsidium fasciculare_
       Cope. Lateral view. × 1.5.

  M. Vertebra of _Phlegethontia linearis_ Cope, from side. × 5.

]

(_m_) The _ribs_ (fig. 8) are very diverse in structure and in their
mode of articulation (541) with the vertebral column. The characters
of the ribs and vertebræ constitute the best means of classification
of these animals so far discovered. In the Branchiosauria the ribs are
always straight, heavy, and short, and articulate intravertebrally upon a
large and strong transverse process. They occur throughout the vertebral
column. There is a single pair of sacral ribs which are not to be clearly
distinguished from the pre-sacral and post-sacral series. The cervical
and caudal ribs are shorter than the dorsal series. The branchiosaurian
rib is composed almost entirely of perichondral ossification. It presents
the same condition as does the humerus of the cow embryo of 2 to 3 inches
in length. The ribs of the branchiosaurs are identical in every way with
the ribs of modern salamanders and form one of the strong arguments in
favor of the relationship of the Branchiosauria to the Caudata. Among the
Microsauria the ribs are always long, slender, curved, and intercentral.
They may be either single or double headed, but usually the former. They
resemble in their characters the ribs of some of the early reptiles and
an attempt has been made to relate the Microsauria (469) to the primitive
reptiles on this basis. The ribs of the other groups are still unknown.
Indeed, representatives of the Temnospondylia and the Stereospondylia are
very scanty in the American Coal Measures. One large rib (plate 22, fig.
4) may represent a labyrinthodont, but nothing is known of the species to
which the rib belonged.

(_n_) The _pectoral girdle_ (187) is a very simple and uniform structure,
although the details of the association of the elements still remain to
be determined. A single, median, usually large and elongate interclavicle
occupies the ventral line of the chest. This is morphologically the same
element which occurs in the middle line of the chest of the lizards.
It is a dermal bone and is usually, especially among the Microsauria
(462), highly sculptured. It varies considerably in size and shape, but
is remarkably uniform throughout the various groups. Lying anterior to
the interclavicle and overlapping its antero-lateral margins lie the two
clavicles, which are usually diamond-shaped and are sculptured, dermal
bones. The position of the coracoid is still uncertain, and in fact its
clear association in the pectoral girdle of these species is still a
question. It seems to be constant in the European (186, 251) species and
is usually represented by a small rounded plate of bone, which in life no
doubt had a large amount of cartilage to form its borders. A cleithrum
(285) has been ascribed to one of the Linton, Ohio, species (plate 15,
fig. 3) by Jaekel (347), but this needs confirmation. An osseous scapula
is usually present, resembling the scapula of modern salamanders, in that
it was largely embedded in cartilage. The position of the pectoral girdle
is largely a matter of doubt, especially for the American species. After
death and before fossilization the girdle was always moved by post-mortem
shifting, so that its exact relation to the ribs and vertebral column
is still in doubt. Credner (186) has restored the pectoral girdle close
behind the head, which would cause an amount of rigidity in the body which
probably did not exist.

(_o_) The _arm_ consists of the humerus, radius, ulna, and 4 digits.
The characters of the arm-bones are such as is constant among primitive
animals and developing mammals. The osseous portion is perichondral.
Epiphyses are totally lacking and it is doubtful if the endochondrium was
at all ossified. The digits are often terminated by ungual phalanges,
although usually the terminal phalanx was merely embedded in the web of
the foot; and among the terrestrial forms a claw was well developed. An
osseous carpus is not known in the species from the Coal Measures. Its
impression indicates a broad hand, well adapted for swimming.

(p) The _pelvic girdle_ consists uniformly (462) of the ilium and
ischium. A small rounded pubis is present in some of the later forms of
Amphibia; it is, however, totally absent from the Coal Measures species.
The condition of the pelvis is paralleled by the partially grown pelvis
of mammalian embryos in which the elements ossify in the order of ilium,
ischium, and pubis. The ilium is always the larger of the elements. It
supported or was attached to the sacral rib by means of a ligamentous
union. The ischium did not ossify completely until the animal was nearly
mature. The union between the elements of the pelvis was probably of a
loose, membranous sort or else the whole mass was embedded in cartilage;
of the two hypotheses the former is the more probable.

The pubis is indicated as a calcified quadrangular plate in a specimen of
_Amphibamus grandiceps_ Cope (478) from the Mazon Creek shales, and it is
present as a rounded osseous element among some of the Permian forms.

(_q_) The _leg_ (fig. 21, B) is composed of the femur, tibia, fibula,
and 5 digits. The tarsus is usually cartilaginous, a single osseous
tarsus (483, 484) being known (plate 23, fig. 1) from America. The distal
phalanges may or may not be clawed, depending on the habits of life of the
animal. The elements of the leg are ossified in a similar manner to those
of the arm.

(_r_) The _ventral scutellation_ (fig. 9), so commonly present among
all groups of Amphibia in the Coal Measures, consists of a series of
ossifications or calcifications in the myocommata. Among modern amphibians
they occur as thin perpendicular planes of connective-tissue which are
sometimes cartilaginous, especially in _Necturus_, regarded by Wilder
(Memoirs of the Boston Society of Natural History, vol. V, No. 9, p.
400, fig. 6, 1903) and by Wiedersheim (605, p. 58) as a homologue or
predecessor of the sternum, although Wiedersheim says:

  "The sternum appears for the first time in Amphibians in the form of
  a small variously shaped plate of cartilage situated in the middle
  line of the chest. It arises as a paired cartilaginous plate in the
  inscriptiones tendineæ of the rectus abdominis muscle, and therefore
  may be looked upon as corresponding to a pair of 'abdominal ribs.'
  Such cartilaginous abdominal ribs must have been present in greater
  numbers in the ancestors of existing Urodeles."

This supposition is fully sustained by the anatomy of the Branchiosauria
(459), which must be looked upon as the actual ancestors of the Caudata.
Wilder says of these structures in _Necturus_ (_op. cit._, p. 400):

  "The several cartilaginous rudiments which represent this part
  (_i.e._, sternum) in _Necturus_ are somewhat difficult of detection
  and thus entirely escaped the attention of the earlier investigators.
  They consist of a number of thin cartilages found in several
  successive myocommata of the pectoral region and confined mainly to
  the area covered by the overlapping epicoracoids."

The homologue of the _ventral scutellæ_ is found in plesiosaurs,
crocodiles, _Sphenodon_, and other reptiles in the "abdominal ribs," and
the same myocommatous ossifications undoubtedly go to the formation of the
chelonian plastron. What the causes were which produced the development
of the ventral scutellæ to such a high degree among the primitive land
vertebrates is uncertain, but they are certainly more highly developed
among the primitive reptiles and amphibians than among the later members
of those classes. Among the Amphibia of the Coal Measures they attained,
in some forms, a high degree of development and differentiation. They are
present in all families so far known, except the Tuditanidæ, in which
the myocommata may have been cartilaginous. The Sauropleuridæ present
the highest development of these structures among the American forms, in
which the scutes are large and osseous. Among the Branchiosauria they
are calcified or partially ossified and are always arranged _en chevron_
on the belly, chest, arms, and throat, their arrangement and direction
of the _chevron_ being modified according to the myomeres of the various
regions. The ventral scutellæ of the European Branchiosauria are figured
and described fully by Credner (192, p. 21, figs. 4 to 11).

[Illustration: Fig. 9.--Ventral scutellæ of _Micrerpeton caudatum_, a Coal
Measures salamander from Mazon Creek. × 5. _f_, femur; _h_, humerus; _ls_,
lines of scutes; _v_, vertebral column.]

(_s_) _Scales_ (fig. 10 and plate 24, figs. 2 and 3) are present on the
body of (462, 485) several species. It is a matter of regret that their
preservation is so imperfect that nothing can be found out as to their
structure. The Linton species, which possess scales, are, of course,
carbonized and hence impracticable for microscopic study, and in the
Mazon Creek species of _Amphibamus_ and _Micrerpeton_ the scales have
been replaced by kaolin. The bodies of two species (_Cercariomorphus
parvisquamis_ and _Ichthyerpeton squamosum_) of the Linton Coal Measures
Amphibia were completely scaled. The scales in the Branchiosauria (462),
so far as they have been observed, are slightly imbricated; rounded, with
concentric markings after the manner of the modern cyprinoid fish-scale.
They are extremely minute, and whether or not they covered the entire body
of the animal is unknown. On the body of _Cercariomorphus_ the scales
have the appearance of being tubercular without imbrication, and they
apparently covered the entire bodily surface of the animal.

[Illustration: Fig. 10.--Horny armor of back of _Hylonomus_. _a_,
imbricated scales; _b_, horny plates; _c_, horny spines or tubercles; _d_,
small imbricated scales. (After Dawson, based on a photograph.)]

Among the Paleozoic Amphibia from Nova Scotia as described by Dawson and
Owen (193, 201, 485) scales are well developed and frequent, although the
details as to their occurrence on the bodies of the animals are still
unknown, since the Nova Scotian species are all based on very fragmentary
remains. Dawson (208, p. 34) has given a detailed discussion of the
discovery and anatomy of the various types of scales possessed by the
species from the Coal Measures of Nova Scotia. Suffice it to say here that
none of the scales appear to be bony, but have a cuticular appearance
with concentric markings. Some of them are tubercular, and Dawson thought
that a few specimens indicated that some of the species possessed scaly
lappets and a dorsal nuchal fringe of scaly skin along the back. He has
indicated these facts in his restorations of the forms. The scales were
all carbonized and burned readily with a strong flame. A section of the
scale shows a thick upper corium with a vascular body (208, pl. IV, fig.
29) much like a fish-scale. Fragments of the skin were also preserved with
the scales. Dawson says of the skin:

  "One of my specimens is a flattened portion of cuticle two and a
  quarter inches in length. The greater part of the surface is smooth
  and shining to the naked eye, and under the microscope shows only a
  minute granulation. A limited portion of the upper and, I suppose,
  anterior part is covered with imbricated scales, which must have been
  membranous or horny, and generally have a small spot or pore near the
  outer margin, some having in addition smaller scales or points on
  their surfaces" (208, pl. IV, figs. 22 and 25).

(_t_) _Muscle_ tissue (fig. 21) is preserved in a single specimen,
previously described by the writer (464, p. 17, pl. 7, fig. 1). The
carbonized muscles show a myomeric arrangement and the portions preserved
probably represent one of the recti muscles of the abdominal wall.

(_u_) The _lateral-line system_ in the Coal Measures Amphibia will be
best understood from a comparative review of the occurrence of these
organs among all extinct Amphibia. Since all the orders of Amphibia are
represented in the Coal Measures, such a review will not be out of place
here.

The preservation of the lateral-line system among ancient Amphibia is due
to the fact that the skull of many forms (especially the later and larger)
are grooved and marked by a regular series of furrows and pits, in which
the sense-organs of the lateral-line system were contained (see fig. 6),
as well as by the preservation of a series of clearly marked scales on
the sides of the tails and bodies of others. The grooves are never arched
over as in the Macropetalichthyidæ, where "in favorable specimens each is
shown to be covered by a delicate roof perforated by two lines of minute
openings" (Dean, N. Y. Acad. Sci. Mem., vol. II, pl. III, p. 115). They
are always widely opened canals, either with perfectly smooth bottoms
and sides or roughened with large pits, or even becoming a series of
well-marked pits. An attempt has been made (458) to homologize the organs
with those of fishes.

The nomenclature adopted here for the canals does not depart from that
used by Allis for _Amia_ (Journ. of Morphology, vol. II, 1889). The
supraorbital and infraorbital canals are readily correlated with those of
the same name in fishes, where they are very clearly marked. The anterior
commissure is also homologous with that of the fishes, as is also the
canal here called the "antorbital commissure." The others are not so
readily homologized. The upper canal (see fig. 6) in the posterior part
of the cranium is here designated the _temporal canal_. It is, however,
clearly a part of the infraorbital of the fishes. Its relations in the
Stegocephala are such that a new name is deemed necessary. The _jugal
canal_ is, I believe, a new formation in Amphibia. The transverse canal of
the amphibian skull is homologous with the "occipital cross-commissure."

The figure (see fig. 6) is a composite picture of the lateral-line system
of the higher or truly stegocephalous Amphibia. The outline of the skull
is based on that of _Eryops_. All of the canals do not exist on any one
skull or in any one order, but all are found somewhere in the group.

[Illustration: Fig. 11.

  A. Skull of _Eoserpeton tenuicorne_ Cope, showing arrangement of
       cranial elements. × 2. _fr_, frontal; _j_, jugal; _mx_, maxilla;
       _n_, nasal; _or_, orbit; _par_, parietal; _pof_, postfrontal;
       _pmx_, premaxilla; _po_, postorbital; _pp_, postparietal; _qj_,
       quadratojugal; _sq_, squamosal; _spt_, supratemporal; _tab_,
       tabulare.

  B. Outline of skull of _Ceraterpeton galvani_ Huxley from the
       Carboniferous of England. Heavy broken lines show the
       distribution of lateral-line canals. × 1. (After Andrews.) _fr_,
       frontal; _par_, parietal; _or_, orbit; _po_, postorbital; _pp_,
       postparietal; _spt_, supratemporal; _tab_, tabulare.

]

The canals have been described in all known orders of fossil Amphibia
and the system is found likewise in all the living orders, including the
Gymnophiona, which have "a strong line of lateral sense-organs" (Gadow).
In the Branchiosauria, the earliest of the true Amphibia (Euamphibia)
and ancestral to the modern Caudata, the lateral-line system is known
on the tails of two genera (462, 478) from the Mazon Creek, Illinois,
shales--_Micrerpeton_ and _Eumicrerpeton_. The system as there defined
has been fully discussed in the description of the anatomical details of
the species, to which reference may be made for further data (pp. 52-60).
Suffice it to say here that the system of sense-organs there preserved
is identical with that of the larval _Necturus_; the lines arising as a
_median_ from the tip of the tail and a _dorsal_ springing from the median
at a distance of a few millimeters from the tip of the tail. The lines are
more evident on account of the fact that the lateral-line sense-organs
were located under specialized pigmented scales. The significance of the
close similarity between the arrangement of the lateral-line systems on
the tail of Necturus, _Micrerpeton_, and _Eumicrerpeton_ is doubtless of
genetic (459) importance, indicating the origin of the caudate Amphibia
from the Branchiosauria by a degenerative or recessive evolution in other
structural characters. This system of sense-organs has been described in
no other branchiosaurian.

The Microsauria (458) are exceedingly interesting in possessing a very
peculiar type of lateral-line system. It is known in a few forms and in
one specimen especially well (_Erpetosaurus tabulatus_) (fig. 22, G). In
this species, which is represented by a single imperfect skull, there are
evidences of a nearly complete lateral-line system of canals and pits.
The occipital cross-commissure is represented on the posterior border
of the skull by a row of elongate pits such as Andrews described for
_Ceraterpeton_ (8). I fail to find in American species the pores described
by Andrews. The temporal canal forms with the jugal canal a complete ring,
much as it is in _Trematosaurus_, only in _Erpetosaurus tabulatus_ the
temporal canal does not touch the tabulare. I think there are indications
of a connection of the temporal canal with the supraorbital. The temporal
canal cuts the supratemporal, the squamosal, and jugal. The jugal canal
lies for the most part on the supratemporal and quadratojugal, and joins
the infraorbital on the jugal. A portion only of the infraorbital canal
is preserved. There is also a portion of the supraorbital canal. It seems
not to be connected with the temporal canal, although there is a possible
indication of this connection. The supraorbital crosses the frontal,
prefrontal, and a part of the nasal. The squamosal element is peculiar
in _Erpetosaurus tabulatus_ in that it is excluded from the parietal by
the extension of the tabulare and postorbital. This condition is found in
several other species of the Microsauria. It will be noticed that with the
changed condition of the squamosal the temporal canal has changed also,
and this is further proof of the close connection between the cranial
elements and the lateral-line canals, as Allis has maintained for _Amia_.
(See in this connection C. J. Herrick, Journ. Comp. Neurol., vol. II, p.
224, 1901.)

The Diplocaulia, an amphibian order allied to the Branchiosauria (477)
and through them to the Caudata, have the lateral-line system apparently
well-developed. The skulls are always crushed flat, so that the canals
are nearly obliterated. On the mandible, however, the canals are clearly
distinct and apparently run the entire course around the mandibular rami.
On a well-preserved skull of _Diplocaulus magnicornis_ Cope there are
indications of three lateral-line canals (477, pl. 1). The infraorbital
is clearly marked as a well-defined groove just below the orbit. The
supraorbital is indicated only for a short distance, and there are
indications of the temporal canal. The operculo-mandibular canal has
its course, for the most part, near the middle of the rami, but as it
approaches the posterior angle of the mandible it suddenly changes its
course and drops down to the lower edge, only to rise again and to come
out strongly marked near the median plane on the posterior angle of the
mandible.

The Temnospondylia, as represented by _Eryops_, _Cricotus_, and
_Archegosaurus_, possess well-developed lateral-line canals (458). H.
von Meyer (428) many years ago made out the course of the canals in
_Archegosaurus_. The greater part of the following description is based
on _Eryops megacephalus_ Cope from the Texas Permian. The entire surface
of the cranial elements in _Eryops_, as in other of the Stegocephala
(458), is covered with coarse pits. The fossæ are present even in
the bottoms of the grooves which represent the lateral-line system,
and are more marked in the members of the Temnospondylia than in the
Stereospondylia.

The occipital cross-commissure occurs in a well-developed form in
_Eryops_. It is short and ends abruptly within the limits of the tabulare.
Its ends are occupied by large pits. The commissure, as in _Amia_, grooves
the postparietal and the tabulare elements. There is no evidence of an
anterior commissure. I think there is evidence of a temporal canal on the
left side of the skull, but am not sure. The jugal and infraorbital canals
are well developed and strongly connected. The jugal canal starts far back
on the supratemporal, and after curving around over the quadratojugal
joins the infraorbital, or rather becomes a part of that canal, somewhere
on the jugal. There is nothing unusual in the infraorbital. The antorbital
commissure is well developed. It is longer and better developed than in
any other known form. The supraorbital canal starts in the region of the
orbit, and after curving downwards to meet the antorbital commissure, ends
abruptly anterior to the nostril. There are faint traces of a lateral-line
canal, the operculo-mandibular, on a poorly preserved mandible of
_Eryops_. It does not differ greatly from that described below for
_Anaschisma_.

Although _Archegosaurus_ has been known for more than a century, we
have had no adequate discussion of the manner of occurrence of the
lateral-line canals. Burmeister (80) gave a figure of the canals as he
thought they occurred on the cranium, but H. von Meyer (428) states that
the representation is inaccurate, and they seem to be based largely on
_Trematosaurus_.

The lateral-line canals occur in well-developed form on the skulls of
the Stereospondylia. The sutures between the elements of the skull are
usually clearly marked by smooth, narrow grooves. The lateral-line canals
can always be distinguished from the sutural grooves by the shape of the
bottom, being =U=-shaped in the former and =V=-shaped in the latter. The
lateral-line canals also at times have their bottoms roughened by pits
occurring in them; the sutural grooves always have smooth bottoms. The
lateral-line canals are usually rather shallow and sometimes broad, with
the edges of the grooves more or less perpendicular, but in _Metoposaurus_
the canals are deep and the borders are sharply incised.

The temporal canals in _Anaschisma_ from the Triassic (49) of Wyoming
are represented by broken furrows. The portions preserved exhibit the
usual downward tendency to unite with the infraorbital on the postorbital
element. In its course forward from the epiotic the temporal canal cuts
the squamosal. The supraorbital canal has an unusually deviating course
in _Anaschisma_, but aside from the minor twists and curves it does not
differ essentially from the same canal in other forms. It ends abruptly
on the anterior end of the muzzle. In its course it gives off the vestige
of an antorbital commissure which tends to join a vestige from the
infraorbital canal. The jugal canal begins broadly at the very posterior
edge of the skull as though it were continued, as it undoubtedly was, to
the body of the animal. In its course forward it joins the infraorbital
canal on the jugal. The course of the infraorbital is not unusual in
any respect. There is no anterior commissure on the skull, nor is the
occipital cross-commissure developed on either skull of the genus at hand.

There are distinct evidences of an operculo-mandibular lateral-line canal
on the mandibles. The canal enters the mandible on the surangular and
passes forward around the mandible as described for _Diplocaulus_ (477).

Other members of the Stereospondylia, such as _Mastodonsaurus_,
_Metoposaurus_, and _Trematosaurus_ possess well-developed lateral-line
canals, but the above description fits, in a general way, the condition in
all genera; and for our present purposes that will suffice.



CHAPTER V.

THE AMPHIBIA OF THE DEVONIAN AND MISSISSIPPIAN OF NORTH AMERICA.


Evidences of the earliest land vertebrates are exceedingly scanty in the
strata between the close of the Silurian and the opening of the Coal
Measures, being represented solely by footprints. In the Devonian our
knowledge of the group is confined to a single footprint, and in the
Mississippian to series of footprints from several localities. These
have been described by Lea (371), Rogers (Geology of Pennsylvania, pt.
II, 1856, p. 831), Barrell (21), Dawson (223), and Branson (50). The
last-named author has described a new species from the Mississippian
of Giles County, Virginia. His description of the footprints, with a
photograph of one of the series, are published herewith (plate 18, fig.
3). Branson (50) has given a _résumé_ of the knowledge of Mississippian
Amphibia in North America.


=Thinopus antiquus Marsh, 1896.=

  Marsh, Am. Jour. Science, II, p. 374, Nov. 1896, with figure.

Type: Specimen No. 784, Yale University Museum.

Horizon: Near top of Chemung, in the upper Devonian.

  [The] "specimen shows one vertebrate footprint in fair preservation,
  and with it part of another of the same series. These impressions are
  of much interest, both on account of their geological age and the size
  and character of the footprints themselves. The one best preserved
  [fig. 12] is nearly 4 inches in length, 2.25 inches in width, and was
  apparently made by the left hind foot. On the inner side in front of
  the heel, a portion of the margin is split off, and this may have
  contained the imprint of another toe. The other footprint was a short
  distance in front, but only the posterior portion is now preserved in
  the present specimen. It is probably the imprint of the forefoot.

  "The specimen [plate 18, fig. 4] ... was ... found in the town of
  Pleasant, one mile south of the Allegheny River, Warren County,
  Pennsylvania, by Dr Charles E. Beecher, who presented it to Yale
  Museum, where it still remains.

  "The geological horizon is near the top of the Chemung in the
  upper Devonian. In the same beds are ripple marks, mud cracks,
  and impressions of rain drops, indicating shallow water and shore
  deposits. Land plants are found in the same general horizon. Marine
  molluscs also occur, and one characteristic form (_Nuculana_) is
  preserved in the footprint slab" (Marsh).

[Illustration: Fig. 12. Copy of Marsh's drawing of footprint of _Thinopus
antiquus_, from the Devonian of Pennsylvania. × 1/3.]

This still remains after nearly 20 years the only evidence of
air-breathing vertebrates in the Devonian of the world.


=Dromopus aduncus Branson.=

  Branson, Jour. Geol., XVIII, No. 4, pp. 356-358, fig. 1, 1910.

Type and other specimens in Oberlin College Museum.

Horizon and type locality: Near the bottom of the Hinton formation in
Giles County, Virginia. (Plate 18, fig. 3.)

The following description of the shales and footprints are from Dr.
Branson's paper cited above:

  "The Hinton shales, like the Mauch Chunk, seem to have been subaerial
  in origin and are made up for the most part of variegated shales
  interbedded with thin layers of argillaceous, fine-grained sandstone.
  The footprints occur in fine-grained sandstone, and remains of land
  plants are not uncommon in the same beds.

  "Twenty-two footprints made by one animal walking in a straight
  course were collected in a slab. They give the impression of having
  been made by a bipedal animal for part of the distance, but after the
  fourth print of the right foot impressions of the forefeet appear. The
  hindfeet had 5 digits, the middle digit being longest and the 2 inside
  of it being only slightly shorter and lying close together. Their
  outer ends were slender and flexible and usually curved inward toward
  the middle toe. The 2 outer digits formed wide angles with the middle
  one and were shorter than the inner ones. The second toe was webbed to
  within 8 mm. of the tip, the third toe to within 23 mm. of the tip.
  The impression of the web is well preserved in only one impression of
  the hindfoot.

  "The forefeet had 4 digits. The 3 inner digits were subequal in
  length, the 2 inner being more flexible and incurved near the ends.
  The outer digit is two-thirds as long as the second. The webbing
  extends about half the length of the digits. The heel impression is
  broader than that of the hindfoot.

"Measurements of _Dromopus aduncus_ Branson.

  Tip of toe to tip of toe in first prints                           21 cm.
    After appearance of forefeet the impressions are the following
      distances apart: 165 mm., 40 mm., 85 mm., 70 mm., 80 mm., 40 mm.,
      150 mm., then back to 20 and 21 cm.

                                                                        mm.
  Length of hindfeet                                                    60
  Width of hindfeet                                               20 to 25
  Length of forefeet                                                    45"



CHAPTER VI.

A HISTORY OF THE CLASSIFICATION OF THE AMPHIBIA, WITH ESPECIAL REFERENCE
TO THE SPECIES FROM THE COAL MEASURES.


It has been necessary, in the course of the present study, to review
thoroughly the classifications which have been proposed for the group. A
classification of some sort is necessary for the proper grouping of the
species which have been recovered from the Coal Measures deposits of this
continent, and my reason for publishing this relatively dry material is
that the classifications formerly proposed (469), as well as the one here
given, may have a proper historical background.

The review of the proposed systems of classification has been much
facilitated by the discovery, in the University of Chicago, of some
notes by the late Dr. George Baur on the "Stegocephali." The notes were
not discovered until after the literature had been pretty thoroughly
covered, and it was a source of some gratification, on comparing notes
with those of Dr. Baur, to find but few omissions. Whether Dr. Baur had
ever contemplated a work on the Stegocephala or not I have been unable to
learn, but it is certain that he carefully and laboriously went through
the literature on the subject and copied by hand the classifications of
each author from 1842 to 1895, together with other notes of interest on
the structure, distribution, and phylogeny, including many tracings. The
classifications given below are taken, in part, from his notes, although
all references have been verified with the original sources.

The first attempt to combine in classification the knowledge of the
extinct and recent amphibians was made by Johannes Jacob von Tschudi in
1839 (574). Previous to that time Goldfuss (295) and von Meyer (418) had
described various species of salamanders and frogs from the Tertiary
deposits of Switzerland, and these Tschudi considered in his following
classification:

  A. Ranæ.
       _a._ _Hylæ._
       _b._ _Cystignathi._
       _c._ _Ranæ._
       _d._ _Ceratophrydes._
       _e._ _Bombinatores._
       _f._ _Bufones._
       _g._ _Pipæ._
  B. Cœciliæ.
       _a._ _Cœciliæ._
  C. Salamandrinæ.
       _a._ _Pleurodeles._
       _b._ _Salamandræ._
       _c._ _Tritones._
       _d._ _Tritonides._
  D. Protoideæ.

Although the remains of _Mastodonsaurus_ had been known and widely
commented on for several years before Tschudi proposed this scheme, he
does not include this genus in his classification of the Amphibia, for
the reason that for nearly a quarter of a century after the discovery of
the labyrinthodonts they were regarded as reptiles, even so eminent an
authority as von Meyer (423) including them in his "System der fossilen
Saurier." The view that the labyrinthodonts were reptiles was at times
disputed, but no one seemed to pay any attention to the argument of
Quenstedt in 1850 that "Die Mastodonsaurier im grünen Keupersandstein
Würtemburgs sind Batrachier" (527), nor to the contention of Vogt (581) in
1854 that "Archegosaurus und alle Labyrinthodonten sind Amphibien, nicht
Reptilien."

In 1842 von Meyer (420) proposed to include all the early forms allied
to the _Mastodonsaurus_ in the "Labyrinthodontes." His definition of the
group follows:

Labyrinthodontes: Saurier deren Zahn-Struktur jener ähnlich ist, welche in
den nach prismatischer Art gebauten Säugethier-Zähnen wahrgenommen wird,
u.s.w.

      I. _Mastodonsaurus Jaeger._ (_Salamandroides_ Jaeger,
           _Batrachosaurus_ Fitzinger, _Labyrinthodon_ Owen.)
           _M. Jaegeri_ Meyer.
     II. _Capitosaurus_ Münster.
         _C. arenaceus_ Münst.
         _C. robustus_ Meyer.
    III. _Metopias_ Meyer.
         _M. diagnosticus_ Meyer.

Three years later von Meyer (423) proposed his "System der fossilen
Saurier," where the extinct Amphibia are treated as follows:

Labyrinthodontes.

    1. Prosthopthalmi (Augen-höhlen in der vordern Hälfte der
         Schädel-Länge)                          _Metopias_ Meyer Keuper.
    2. Mesopthalmi (Augen-höhlen in der mitte der Schädel)
                             _Mastodonsaurus_ Jaeger Keuper, Muschelkalk.
    3. Opisthopthalmi (Augen-höhlen in der hintern Hälfte der
         Schädel-Länge)                    _Capitosaurus_ Münster Keuper.
    4. Labyrinthodonten ungewisser Stellung.
        _Labyrinthodon_ Owen                                      Keuper.
        _Xestorrhytias_ Meyer                                Muschelkalk.
        _Odontosaurus_ Meyer                            Bunter Sandstein.
        _Trematosaurus_ Braun                           Bunter Sandstein.

No other classification was proposed for the extinct Amphibia for 15
years, when Owen (512) in 1859 proposed the new order Ganocephala and
retained von Meyer's Labyrinthodontes under Labyrinthodontia. Owen's
classification is as follows:

Class--Reptilia.
Order I. Ganocephala.
      Genera: _Archegosaurus_, _Dendrerpeton_, _Raniceps_.
Order II. Labyrinthodontia.
      Genera: _Mastodonsaurus_, _Anisopus_, _Trematosaurus_, _Metopias_,
        _Capitosaurus_, _Zygosaurus_, _Xestorrhytias_.

In his Paleontology published in 1861, Owen gives the same classification,
but adds new genera.

Huxley in 1863 (332) did not accept Owen's Ganocephala, but instead
proposed the following:

Labyrinthodontia.
  A. Archegosauria. _Archegosaurus_, _Pholidogaster_.
  B. Mastodonsauria. _Mastodonsaurus_, _Labyrinthodon_, _Capitosaurus_,
       _Trematosaurus_.

In the same year Dawson proposed (208) the term Microsauria to include
the genera _Hylonomus_, _Dendrerpeton_, and _Hylerpeton_, all known from
the Carboniferous rocks of Nova Scotia. Two years later Cope proposed
the new order Xenorhachia (105) for the reception of the form _Amphibamus
grandiceps_ from the Coal Measures of Illinois. He gave as the characters
of this order cartilaginous vertebræ and the absence of ribs.

In 1866 Owen proposed (516) the most elaborate and comprehensive scheme of
classification which had thus far been offered. His classification is as
follows:

  Subclass Dipnoa.
    Order Ganocephala (extinct). Genera: _Archegosaurus_,
      _Dendrerpeton_, etc.
    Order Labyrinthodontia. Genera: _Labyrinthodon_, _Rhombopholis_, etc.
    Order Batrachia.
      Suborder Ophiomorpha. Family: Cœcilidæ.
      Suborder Ichthyomorpha. Family: Proteidæ, Salamandridæ.
      Suborder Theriomorpha (Anura).
        Family 1. _Aglossa._
        Family 2. _Ranidæ._
        Family 3. _Hylidæ._
        Family 4. _Bufonidæ._

Haeckel the same year proposed (312) an entirely different scheme of
classification nd in some respects more acceptable than Owen's. Haeckel's
classification is as follows:

  Class Amphibia.
    Subclass I. Phractamphibia.
      Ordnung i. Ganocephala.
        Genera: _Archegosaurus_, _Dendrerpeton_, _Raniceps_.
      Ordnung 2. Labyrinthodonta.
        Genera: _Baphetes_, _Zygosaurus_, _Mastodonsaurus_,
          _Trematosaurus_, _Capitosaurus_.
      Ordnung 3. Peromela.
    Subclass II. Lissamphibia.
      Ordnung i. Socobranchia.
        Genera: _Siren_, _Proteus_, _Menobranchus_, etc.
      Ordnung 2. Sozura (Caudata).
        Genera: _Cryptobranchus_, _Triton_, _Salamandra_.
      Ordnung 3. Anura (Ecaudata).
        Families: _Aglossa_, _Bufonidæ_, _Ranidæ_.

This classification is further elaborated in the edition of 1895.

Cope in 1868 proposed (110) the scheme of classification which was in
use for some time, although it has since suffered some change. His
classification follows:

Batrachia.
  Order 1. Trachystoma.
  Order 2. Proteida.
  Order 3. Urodela.
  Order 4. Gymnophiona.
  Order 5. Stegocephali.
    Suborder Xenorhachia.
      _Amphibamus grandiceps_ Cope.
    Suborder Microsauria.
      Genera: _Pelion_ Wyman, _Hylonomus_ Dawson, _Pariostegus_ Cope,
        _Dendrerpeton_ Owen, _Hylerpeton_ Owen, _Brachydectes_ Cope,
        _Sauropleura_ Cope, _Œstocephalus_ Cope, _Molgophis_ Cope.
    Suborder Labyrinthodontia.
      Genera: _Dictyocephalus_ Leidy, _Centemodon_ Lea, _Baphetes_ Owen,
        _Eupelor_ Cope.

Huxley in 1869 proposed (335) the following classification, which does not
differ essentially from that proposed in 1863:

Amphibia.
  Order 1. Urodela.
  Order 2. Batrachia.
  Order 3. Gymnophiona.
  Order 4. Labyrinthodontia.
    Suborder Archegosauria.
    Suborder Mastodonsauria.

The next classification of the extinct Amphibia of any importance was
that devised by the committee (450) for the British Association in 1874.
This committee was formed of Huxley, Harkness, Henry Woodward, Thompson,
and Brigg, with Miall as secretary. This classification is, however,
too cumbersome and has never come into general use, and indeed none but
English authors have paid it a great deal of attention, although the
contribution was a valuable one. The group Aistopoda, which was the ninth
group proposed by the committee, has generally been accepted as the group
represented by the snake-like forms. The committee's classification
follows:

Labyrinthodontia.
  Section I. Euglypta.
    Genera: _Mastodonsaurus_, Jaeger; _Capitosaurus_, Münst.; _Pachygonia_,
      Huxley; _Trematosaurus_, Braun; _Gonioglyptus_, Huxley; _Metopias_,
      von Meyer; _Labyrinthodon_, Owen; _Diadetognathus_, Miall;
      _Dasyceps_, Huxley; _Anthracosaurus_, Huxley.

  Section II. Brachyopina.
    Genera: _Brachyops_, Owen; _Micropholis_, Huxley; _Rhinosaurus_,
      Waldheim; _Bothriceps_, Huxley.

  Section III. Chauliodonta.
    Genera: _Loxomma_, Huxley; _Zygosaurus_, Eich.; _Melosaurus_, Meyer.

  Section IV. Arthroödonta.
    Genera: _Batrachiderpeton_, Hancock and Atthey; _Pteroplax_, Hancock
      and Atthey.

  Section V. An uncharacterized group.
    Genera: _Pholidogaster_, Huxley; _Ichthyerpeton_, Huxley;
      _Pholiderpeton_, Huxley.

  Section VI. Archegosauria, von Meyer.
    Genera: _Archegosaurus_, Goldfuss.

  Section VII. Heleothrepta.
    Genera: _Lepterpeton_, Huxley.

  Section VIII. Nectridea.
    Genera: _Urocordylus_, Huxley; _Keraterpeton_, Huxley.

  Section IX. Aistopoda.
    Genera: _Ophiderpeton_, Huxley; _Dolichosoma_, Huxley.

  Section X. Microsauria, Dawson.
    Genera: _Dendrerpeton_, Owen; _Hylonomus_, Dawson; _Hylerpeton_, Owen.

The schemes of classification used for the next 10 years did not depart in
any appreciable degree from those already given.

In 1875 Cope, in his Check-list of North American Batrachia and
Reptilia (120), with a systematic list of the higher groups, published
the following classification as being "adopted provisionally by the
Smithsonian Institution":

  Class Batrachia.
    Order Anura. (Anura, Duméril; Salientia, Merrem, Gray.)
      Raniformia. (Raniformia, Cope, Nat. Hist. Rev., V, 114, 1865.)
        Families: _Ranidæ_, _Colostheidæ_.
      Firmisternia. (Bufonoid Raniformia, Cope, Jour. Acad. Nat. Sci.,
        Philadelphia, n.s., VI, 190, 1867.)
        Families: _Dendrobatidæ_, _Phryniscidæ_, _Engystomidæ_,
          _Breviceptidæ_.
      Gastrechmia. (Gastrechmia, Cope, Jour. Acad. Nat. Sci.,
        Philadelphia, n.s., VI, 198, 1867.)
        Family: Hemisidæ.
      Bufoniformia. (Bufoniformia, Duméril et Bibron, _partim_; Cope,
        _partim_.)
        Families: _Rhinophrynidæ_, _Bufonidæ_, _Batrachophrynidæ_.
      Aglossa.
        Family: _Pipidæ._
      Odontaglossa.
        Family: _Dactylethridæ._
      Arcifera. (Arcifera, Cope, N. H. Rev., V, 104, 1865.)
        Families: _Cystignathidæ_, _Hemiphractidæ_, _Hylidæ_,
          _Scaphiopidæ_, _Pelodytidæ_, _Asterophrydidæ_, _Discoglossidæ_.
    Order Stegocephali. (Stegocephali Cope, Proc. Acad. Nat. Sci.,
      Philadelphia, 1868, 209.)
      Labyrinthodontia.
        Families: _Baphetidæ_ Cope, _Anthracosauridæ_ Cope.
      Ganocephala.
        Family: _Colosteidæ_ Cope.
      Microsauria.
        Families: _Phlegethontiidæ_ Cope, _Molgophidæ_ Cope, _Ptyoniidæ_
          Cope, _Tuditanidæ_ Cope,
      _Peliontidæ_ Cope.
    Order Gymnophiona. (Gymnophiona Müller.)
        Family: _Cœciliidæ_ Gray, 1850.
    Order Urodela.
        Families: _Pleurodelidæ_ Gray, 1858; _Salamandridæ_: Gray, 1858;
          _Hynobiidæ_ Cope, 1866; _Desmognathidæ_ Cope, 1866; Thoriidæ
          Cope, 1869; _Plethodontidæ_ Cope, 1866; _Amblystomidæ_ Cope,
          1866; _Menopomidæ_ (_Protonopsidæ_ Gray, 1850), _Amphiumidæ_
          Cope, 1866; _Cocytinidæ_ Cope.
    Order Proteida.
        Family: _Proteidæ_ Gray, 1850.
    Order Trachystomata.
        Family: _Sirenidæ_ Gray, 1850.

In 1885 Cope proposed 2 new orders, which he arranges with the other
orders already known, as follows:

              { Order   I. Rachitomi.      Order   V. Urodela.
  Batrachia.  { Order  II. Embolomeri.     Order  VI. Trachystomata.
              { Order III. Stegocephali.   Order VII. Anura.
              { Order  IV. Proteida.

The new order Rachitomi was to include forms like Eryops and the new order
Embolomeri was to include forms like Cricotus; the other orders were as
they had been given before.

Zittel in 1888 proposed (642) the next classification of any note in his
"Handbuch der Paleontologie," where it stands as follows:

  Classe Amphibia.
    Ordnung 1. Stegocephali.
      Unterordnung 1. Lepospondyli.
        Familie 1. _Branchiosauridæ_ Fritsch.
           "    2. _Microsauria_ Dawson.
           "    3. _Aistopoda_ Miall.
      Unterordnung 2. Temnospondyli.
        Genera: _Archegosaurus_, _Eryops_, etc.
      Unterordnung 3. Stereospondyli.
        Familie 1. _Gastrolepidoti_.
           "    2. _Labyrinthodonta_.
    Ordnung 2. Cœciliæ.
    Ordnung 3. Urodela.
      Unterordnung 1. Ichthyoidea.
          Familie 1. _Phanerobranchia_.
             "    2. _Cryptobranchia_.
      Unterordnung 2. Salamandrina.
    Ordnung 4. Anura.
      Unterordnung 1. Phaneroglossa.
         Familie 1. _Ranidæ_.
             "    2. _Bufonidæ_.
             "    3. _Cystignathidæ_ Cope.
             "    4. _Pelobatidæ_ Boul.
             "    5. _Discoglossidæ_ Cope.
             "    6. _Palæobatrachidæ_ Cope.

Lydekker (393) in the next year proposed a system of classification which
did not depart widely from that proposed (450) by the committee of the
British Association for 1874. Lydekker's classification is as follows:

  Class Amphibia.
    Order   I. Labyrinthodontia.
      Suborder 1. Branchiosauria.
        Family _Protritonidæ_.
           "   _Apateonidæ_.
      Suborder 2. Aistopoda.
        Family _Dolichosomatidæ_.
      Suborder 3. Microsauria.
        Family _Urocordylidæ_.
           "   _Limnerpetidæ_.
           "   _Hyloplesionidæ_.
           "   _Microbrachidæ_.
    Suborder 4. Labyrinthodontia vera.
        Family _Archegosauridæ_.
           "   _Diplospondylidæ_.
           "   _Nyraniidæ_.
           "   _Dendrerpetidæ_.
           "   _Anthracosauridæ_.
           "   _Mastodonsauridæ_.
      Uncertain family, _Eosaurus_.
    Order  II. Apoda.
    Order III. Caudata.
        Family _Hylæobatrachidæ_.
           "   _Sirenidæ_.
           "   _Proteidæ_.
           "   _Amphiumidæ_.
           "   _Salamandridæ_.
    Order IV. Ecaudata.
        Family _Discoglossidæ_.
           "   _Pelobatidæ_.
           "   _Palæobatrachidæ_.
           "   _Cystignathidæ_.
           "   _Ranidæ_.

In 1890 Döederlein proposed a scheme of classification which is notable on
account of the peculiar relations which it expresses between the groups
relations which, in reality, do not exist. His classification is as
follows:

  Class Amphibia.
     Ordnung   I. Stegocephali.
        A. Microsauria.
            Unterordnung 1. Branchiosauri.
                Genera: _Branchiosaurus_, _Dawsonia_, _Melanerpeton_,
                  _Pelosaurus_.
            Unterordnung 2. Sauromorphi.
              Familie 1. _Hylonomidæ_.
                 "    2. _Nectridæ_.
                 "    3. _Aistopodidæ_.

        B. Ganocephala.
            Unterordnung 1. Rhachitomi.
                 "       2. Embolomeri.
                 "       3. Labyrinthodontia.
     Ordnung  II. Urodela.
     Ordnung III. Gymnophiona.
     Ordnung  IV. Anura.

In 1890 Lydekker used the same classification, with minor changes, which
he had used in his Paleontology. Credner, who wrote at about the same time
(193), followed Zittel's classification. Zittel in 1895 merely repeated
his former classification. In 1898 appeared Smith Woodward's Paleontology,
where the following scheme is adopted:

  Class Batrachia.
     Order   I. Stegocephalia.          Order  II. Gymnophiona.
        Suborder 1. Branchiosauria.     Order III. Caudata.
           "     2. Aistopoda.          Order  IV. Ecaudata.
           "     3. Microsauria.
           "     4. Labyrinthodontia.

Hay's Catalogue of Fossil Vertebrata of North America contains the
next scheme for the classification of the Amphibia which pays especial
attention to the extinct forms. His classification is as follows:

  Class Batrachia Macartney, 1802.
    Order Stegocephali Cope, 1868.
      Suborder Microsauria Dawson, 1863.
        Family _Protritonidæ_ Lydekker, 1889.
            Genera: _Amphibamus_ Cope, _Pelion_ Wym.
        Family _Molgophidæ_ Cope, 1875.
            Genera: _Phlegethontia_ Cope, _Molgophis_ Cope.
        Family _Hylonomidæ_ Fritsch, 1883.
            Genera: _Hylonomus_ Dawson, _Smilerpeton_ Dawson, _Hylerpeton_
              Owen, _Fritschia_ Dawson; _Brachydectes_ Cope.
        Family _Ptyoniidæ_ Cope, 1875.
            Genera: _Keraterpeton_ Huxley, _Œstocephalus_ Cope, _Ptyonius_
              Cope, _Ctenerpeton_ Cope.
        Family _Tuditanidæ_ Cope, 1875.
            Genera: _Tuditanus_ Cope, _Cocytinus_ Cope.
        Family _Diplocaulidæ_ Cope, 1881.
            Genus: _Diplocaulus_ Cope.
            Lepospondylous Genera of uncertain position: _Amblyodon_
              Dawson, _Hyphasma_ Cope, _Eurythorax_ Cope, _Thyrsidium_
              Cope, _Pleuroptyx_ Cope, _Cercariomorphus_ Cope.
      Suborder Apœcospondyli Hay, 1902.
        Family _Dendrerpetontidæ_ Fritsch, 1889.
            Genera: _Dendrerpeton_ Owen, _Baphetes_ Owen, _Platystegos_
              Dawson.
        Family _Sauropleuridæ_ Hay, 1902.
            Genera: _Sauropleura_ Cope, _Leptophractus_ Cope.
        Family _Archegosauridæ_.
            Genera: _Trimerorhachis_ Cope, _Dissorophus_ Cope.
        Family _Cricotidæ_ Cope, 1884.
            Genera: _Cricotus_ Cope.
        Family _Anthracosauridæ_.
            Genus: _Eosaurus_ Marsh.
        Family _Eryopidæ_ Cope, 1882.
            Genera: _Eryops_ Cope, _Ichthycanthus_ Cope, _Zatrachys_ Cope,
              _Anisodexis_ Cope, _Acheloma_ Cope.
        Family _Mastodonsauridæ_ Huxley, 1863.
            Genera: _Mastodonsaurus_ Jaeger, _Eupelor_ Cope, _Pariostegus_
              Cope, _Dictyocephalus_ Leidy.
    Order Urodela.
            Genera: _Scapherpeton_ Cope, _Hemitrypus_ Cope.
    Order Salientia Laurenti, 1768.
        Family _Ranidæ_.
            Genera: _Rana_ Linné, _Eobatrachus_ Marsh.

This classification given by Hay is only for the forms which occur in
North America.



CHAPTER VII.

CLASSIFICATION OF AMPHIBIA ADOPTED IN THIS WORK, AND A LIST OF THE COAL
MEASURES AMPHIBIA FROM NORTH AMERICA.


A few words of explanation will be necessary for an understanding of the
following classification. The term Amphibia Linné, 1758, is, according
to Stejneger (550), the correct term for the entire group, and this term
is adopted. The term _Stegocephala_, formerly used as a group name for
the entire Carboniferous, Permian, and Triassic Amphibia, regardless of
structure, has been retained as a third subclass. The choice, so far as
priority is concerned, between Labyrinthodontia and Stegocephala, is not
easy. The terms, however, imply different structures. The labyrinthodonts
proper have stereospondylous vertebræ, while the Stegocephala have either
temnospondylous or stereospondylous vertebræ; so the latter term has been
adopted.

The ordinal terms are those which have been used previously as subordinal,
sectional, or family names, with the exception of the new ordinal term
"Diplocaulia" (477). The term Branchiosauria is well-established, and
it is here retained with the definitions previously given. The same may
be said for the Microsauria, although Dawson first (208) regarded it
as a family, though giving the term an ordinal form. The Aistopoda are
not entitled to consideration as a group for reasons which are given
subsequently. The Temnospondylia and the Stereospondylia, the Embolomeri
and the Rachitomi may or may not be good group names, but they have
priority, so far as our knowledge of structure goes. They have been
retained in their original meanings. They have been variously regarded as
sections, superfamilies, groups, and subfamilies.

The following list of species is arranged according to the proposed scheme
of classification:

  Class Amphibia Linné, 1758. Devonian to Recent.
    Subclass Euamphibia Moodie, 1909. Coal Measures to Recent.
      Order Branchiosauria Lydekker, 1889. Coal Measures to Permian.
        Family _Branchiosauridæ_ Fritsch, 1879.
            _Micrerpeton caudatum_ Moodie, Mazon Creek.
            _Eumicrerpeton parvum_ Moodie, Mazon Creek.
            _Mazonerpeton longicaudatum_ Moodie, Mazon Creek.
            _Mazonerpeton costatum_ Moodie, Mazon Creek.
            _(?) Sparodus_ sp. indet. Dawson, Nova Scotia.
      Order Caudata Duméril, 1806. Coal Measures to Recent.
        Suborder Proteida Cope, 1868. Coal Measures, Eocene, and Recent.
          Family _Cocytinidæ_ Cope, 1875.
            _Cocytinus gyrinoides_ Cope, Linton, Ohio.
            _Erierpeton branchialis_ Moodie, Mazon Creek.
            _Hyphasma lævis_ Cope, Linton, Ohio.
      Order Diplocaulia Moodie, 1912. Coal Measures to Permian.
        Family _Diplocaulidæ_ Cope, 1881.
            _Diplocaulus salamandroides_ Cope, Salt Fork, Illinois.
      (?) Order Salientia Laurenti, 1768. Coal Measures (?) to Recent.
            Family _Peliontidæ_ Cope, 1875.
             _Pelion lyelli_ Wyman, Linton, Ohio.
    Subclass Lepospondylia Zittel, 1887. Coal Measures.
      Order Microsauria Dawson, 1863. Coal Measures.
        Family _Hylonomidæ_ Fritsch, 1883.
          _Hylonomus latidens_ Dawson, Nova Scotia.
          _Hylonomus lyelli_ Dawson, Nova Scotia.
          _Hylonomus multidens_ Dawson, Nova Scotia.
          _Hylonomus wymani_ Dawson, Nova Scotia.
          _Smilerpeton aciedentatum_ Dawson, Nova Scotia.
          _Hylerpeton dawsonii_ Owen, Nova Scotia.
          _Hylerpeton intermedium_ Dawson, Nova Scotia.
          _Hylerpeton longidentatum_ Dawson, Nova Scotia.
          _Fritschia curtidentata_ Dawson, Nova Scotia.
          _(?) Amblyodon problematicum_ Dawson, Nova Scotia.
        Family _Tuditanidæ_ Cope, 1875.
          _Tuditanus punctulatus_ Cope, Linton, Ohio.
          _Tuditanus brevirostris_ Cope, Linton, Ohio.
          _Tuditanus minimus_ Moodie, Cannelton, Pa.
          _Tuditanus longipes_ Cope, Linton, Ohio.
          _Tuditanus walcotti_ Moodie, Linton, Ohio.
          _Erpetosaurus acutirostris_ Moodie, Linton, Ohio.
          _Erpetosaurus minutus_ Moodie, Cannelton, Pa.
          _Erpetosaurus obtusus_ Cope, Linton, Ohio.
          _Erpetosaurus radiatus_ Cope, Linton, Ohio.
          _Erpetosaurus sculptilis_ Moodie, Cannelton, Pa.
          _Erpetosaurus tabulatus_ Cope, Linton, Ohio.
          _Erpetosaurus tuberculatus_ Moodie, Linton, Ohio.
          _Odonterpeton triangularis_ Moodie, Linton, Ohio.
        Family _Stegopidæ_ Moodie, 1909.
          _Stegops divaricata_ Cope, Linton, Ohio.
        Family _Urocordylidæ_ Lydekker, 1890.
          _Diceratosaurus punctolineatus_ Cope, Linton, Ohio.
          _Diceratosaurus lævis_ Moodie, Linton, Ohio.
          _Diceratosaurus robustus_ Moodie, Linton, Ohio.
          _Eoserpeton tenuicorne_ Cope, Linton, Ohio.
        Family _Amphibamidæ_ Moodie.
          _Amphibamus grandiceps_ Cope, Mazon Creek.
          _Amphibamus thoracatus_ Moodie, Mazon Creek.
          _Cephalerpeton ventriarmatum_ Moodie, Mazon Creek.
        Family _Nyraniidæ_ Lydekker, 1889.
          _Ichthyerpeton squamosum_ Moodie. Linton, Ohio.
          _Cercariomorphus parvisquamis_ Cope, Linton, Ohio.
        Family _Ptyoniidæ_ Cope, 1875.
          _Ptyonius nummifer_ Cope, Linton, Ohio.
          _Ptyonius marshii_ Cope, Linton, Ohio.
          _Ptyonius vinchellianus_ Cope, Linton, Ohio.
          _Ptyonius pectinatus_ Cope, Linton, Ohio.
          _Ptyonius serrula_ Cope, Linton, Ohio.
          _Œstocephalus remex_ Cope, Linton, Ohio.
          _Œstocephalus rectidens_ Cope, Linton, Ohio.
          _Thyrsidium fasciculare_ Cope, Linton, Ohio.
        Family _Ichthycanthidæ_ Moodie.
          _Ichthycanthus ohiensis_ Cope, Linton, Ohio.
          _Ichthycanthus platypus_ Cope, Linton, Ohio.
        Family _Molgophidæ_ Cope, 1875.
          _Molgophis macrurus_ Cope, Linton, Ohio.
          _Molgophis brevicostatus_ Cope, Linton, Ohio.
          _Molgophis wheatleyi_ Cope, Linton, Ohio.
          _Erpetobrachium mazonensis_ Moodie, Mazon Creek.
          _Pleuroptyx clavatus_ Cope, Linton, Ohio.
          _Phlegethontia linearis_ Cope, Linton, Ohio.
          _Phlegethontia serpens_ Cope, Linton, Ohio.
        Family _Sauropleuridæ_ Hay, 1902.
          _Sauropleura digitata_ Cope, Linton, Ohio.
          _Sauropleura newberryi_ Cope, Linton, Ohio.
          _Sauropleura scutellata_ Newberry, Linton, Ohio.
          _Sauropleura pauciradiata_ Cope, Linton, Ohio.
          _Sauropleura longidentata_ Moodie, Linton, Ohio.
          _Sauropleura foveata_ Cope, Linton, Ohio.
          _Sauropleura (Anisodexis) enchodus_ Cope, Linton, Ohio.
          _Sauropleura_ sp., Linton, Ohio.
          _Ctenerpeton alveolatum_ Cope, Linton, Ohio.
          _Saurerpeton latithorax_ Cope, Linton, Ohio.
          _Leptophractus obsoletus_ Cope, Linton, Ohio.
          _Leptophractus dentatus_ Moodie, Linton, Ohio.
          _Leptophractus lineolatus_ Cope, Linton, Ohio.
      Order Temnospondylia Zittel, 1887. Coal Measures and Permian.
        Family _Cricotidæ_ Cope, 1884.
          _Spondylerpeton spinatum_ Moodie, Mazon Creek, Ill.
        Family _Eryopidæ_ Cope, 1882.
          _Eryops_ sp. indet., Pitcairn, Pa.
        Family _Macrerpetidæ_ Moodie, 1909.
          _Macrerpeton huxleyi_ (Cope), Linton, Ohio.
          _Macrerpeton deani_ Moodie, Linton, Ohio.
        Family _Anthracosauridæ_ Cope, 1875.
          _Eosaurus acadianus_ Marsh, Nova Scotia.
          _Eobaphetes kansensis_ Moodie, Kansas.
          _Baphetes planiceps_ Owen, Nova Scotia.
          _Baphetes minor_ Dawson, Nova Scotia.
          _Dendrerpeton acadianum_ Owen, Nova Scotia.
          _Dendrerpeton oweni_ Dawson, Nova Scotia.
          _(?)Platystegos loricatum_ Dawson, Nova Scotia.
          Genera and species of uncertain position:
            _Amblyodon problematicum_ Dawson, Nova Scotia.
            _Proterpeton gurleyi_ Moodie, Illinois.
            _Brachydectes newberryi_ Cope, Linton, Ohio.
      Order Stereospondylia Zittel, 1887. Coal Measures (?) and Triassic.
        Family _Mastodonsauridæ_ Huxley, 1863.
          _Mastodonsaurus_ sp. indet., Kansas.

The above list of species is interesting in that it shows the diversity
of structure among the Coal Measures Amphibia. There are at present 88
species known, many of them incompletely, divided among 17 families and
5 orders. The majority of the species are from the Linton Coal Measures,
there being 50 species described or indicated from these beds. The Mazon
Creek shales have furnished 10 species; Nova Scotia 18 species; the
remainder of the species are from various localities.



CHAPTER VIII.

DEFINITION OF THE CLASS AMPHIBIA LINNÉ, 1758, DEVONIAN TO RECENT.

(World-wide distribution.)


  Cold-blooded vertebrates; aquatic or partially terrestrial in
  habit; body scaled or naked or partly covered with bony or horny
  plates; abdomen sometimes protected by closely packed scutes,
  scales, or rods; skull completely roofed-over or with a single
  vacuity; pterygoid-palatine arch complete or wanting; stapes always
  present; two occipital condyles, sometimes cartilaginous; skull
  bones pitted and grooved by the lateral-line canals, or smooth and
  lateral-line canals wanting; parasphenoid well developed; palatine
  vacuities, large, small, or absent; basioccipital partly or entirely
  cartilaginous; sclerotic plates present or absent; mouth always
  terminal; teeth sharply conical, smooth, or plicated, with walls
  sometimes extremely complicated by the infolding of the dentine and
  enamel. Vertebræ procœlous, opisthocœlous, amphicœlous, amphiplatyan,
  temnospondylous, stereospondylous, or cartilaginous; notochord often
  persistent; column divisible into cervical, dorsal, and caudal series;
  cervical series, so far as known, always short; dorsal region long
  or short; a single sacral or two; caudal series short, very long, or
  absent. Pectoral girdle composed of an osseous scapula, cleithrum,
  clavicle, interclavicle, and coracoid with various relations; sternum
  undeveloped; pectoral girdle of membrane bones; in Triassic forms
  producing the effect of a plastron on account of the high development
  of the clavicles and interclavicle. Pelvis usually composed of an
  osseous ilium and ischium; pubis when osseous surrounded by large
  amounts of cartilage, usually cartilaginous, sometimes calcified.
  Limbs ambulatory, natatory, or wanting; limb bones composed either
  entirely of perichondrium or of perichondrium and a small amount
  of endochondrium; radius and ulna, and tibia and fibula free or
  fused. Digits 3 to 5, usually 4 for the hand and 5 for the foot.
  Terminal phalanges sometimes clawed. Carpus and tarsus osseous or
  cartilaginous, usually the latter. Ribs never attached to a sternal
  apparatus, single or double headed or intermediate, long and curved
  or short and straight. Articulation with vertebral column inter- or
  intra-central. Respiration both branchial and pulmonary; branchiæ
  persistent and osseous in some forms. Development by metamorphosis
  either in the egg membrane, on the back of the mother, or in the
  water. No amnion or allantois. Heart with a single ventricle and 3 or
  4 pairs of aortic arches; postcava always present in the recent forms.


DEFINITION OF SUBCLASS EUAMPHIBIA, MOODIE, 1909. COAL MEASURES TO RECENT.

(World-wide distribution.)

  Moodie, Trans. Kans. Acad. Sci., 1909, p. 243.

  Moodie, Geol. Mag., n. s., Dec. V, vol. VI, p. 220, May, 1909.

The present group was established for the reception of the Branchiosauria
and their descendants, the Caudata, with the related forms, the Apoda. The
Salientia are included provisionally, since there is no evidence of the
origin or relationship of this group of animals to other Euamphibia save
that they have attained the same stage of evolution. They are in no way
closely related to any known group of Amphibia, recent or extinct, but
they stand on the same plane of development as the Caudata and present
similar structures, _i.e._, a single ventricle in the heart, external
branchiæ in the young, a glandular skin, perichondral bone, and a large
parasphenoid. The origin of the Salientia is a puzzle and must remain so
until further paleontological evidence is forthcoming. Wyman, Cope, and
the writer have all remarked on the similarity of structure between the
Salientia and the single known specimen of _Pelion lyelli_ Wyman from the
Linton, Ohio, Coal Measures.

The subclass Euamphibia may be defined as follows: Aquatic or terrestrial
Amphibia; development by metamorphosis; external branchiæ present in
the young; bones almost entirely perichondral; carpus and tarsus never
ossified; osseous pubis absent; vertebræ usually amphicœlous with
persistent notochord; ribs short and straight or flat and slightly curved,
or absent; digits 4 in the hand and 5 in the foot; skull never grooved or
pitted, nor cut by the lateral-line canals; lateral-line organs present in
the skin; sclerotic plates present or absent; tail long and flattened or
absent. Ribs in _Triton walthi_ are secondarily long and curved.


DEFINITION OF THE ORDER BRANCHIOSAURIA LYDEKKER, 1890. COAL MEASURES AND
PERMIAN OF NORTH AMERICA AND EUROPE.

  Lydekker, Cat. Fossil Reptilia and Amphibia, pt. IV, p. 208, 1890.

Extinct, salamander-like amphibians, with broad, obtusely rounded
cranium; external branchiæ present in young; sclerotic plates present;
bones of the cranium not ornamented with deep pits and grooves nor cut
by the lateral-line canals, though sometimes ornamented with slight
scorbiculations; notochord always persistent; vertebræ cartilaginous (in
caudal region) or but partially ossified, the ossification being entirely
perichondral; a single sacral vertebra; transverse process of vertebræ
large in dorsal region; ribs always short, straight, and heavy, present
throughout the length of the vertebral column and borne on the transverse
processes centrally; caudal region of moderate length with elongate
fleshy tail; usually 20 presacrals, of which 4 or 5 may be considered
cervicals; limbs natatory and always present, well developed; elements of
the appendicular skeleton composed entirely of perichondrium; carpus and
tarsus cartilaginous; digits 4 in the hand and 5 in the foot; phalangeal
formula for the hand usually 2-2-3-2 and for the foot 2-3-4-3-2; distal
phalanges not clawed; abdomen covered with closely packed corneous scutes
or scales; body naked or covered with minute horny scales; median and
dorsal lateral lines present on the posterior part of body and on tail.



CHAPTER IX.

THE AMERICAN COAL MEASURES BRANCHIOSAURIDÆ.


Definition Op the Family Branchiosauridæ Fritsch, 1879. Coal Measures and
Permian Op North America and Europe.

  Fritsch, Fauna der Gaskohle, Bd. I, p. 69, fig. 30, 1879.

  Lydekker, Cat. Fossil Reptilia and Amphibia, pt. IV, p. 210, 1890
    (Protritonidæ;).

Stegocephalic, salamander-like animals, with broad, anteriorly truncate
skull. Teeth smooth with large pulp-cavity. The parasphenoid narrowed
anteriorly, posteriorly expanded to a shield-shaped plate. Vertebra;
with the notochord persistent and intravertebrally expanded. Pelvis well
developed, the ilium and ischium osseous with large cartilaginous margins,
the pubis unknown, possibly hyaline cartilage. Ribs short, straight,
present on almost all vertebræ. Skin with delicately ornamented scales.
Eyes with sclerotic plates. Palatal elements toothless or with small
tooth-like tubercles on pterygoids and palatines. Ventral armature on
throat, chest, and abdomen, extending on to the limbs, consisting of small
delicate scutellæ arranged in a chevron pattern.

The above definition is modified from Fritsch (Fauna der Gaskohle, Bd. I,
p. 69, 1879).

The North American species are: (?) _Sparodus_ sp. indet. Dawson,
_Micrerpeton caudatum_ Moodie, _Mazonerpeton longicaudatum_ Moodie,
_Mazonerpeton costatum_ Moodie, _Eumicrerpeton parvum_ Moodie.


=Genus MICRERPETON Moodie.=

  Moodie, Jour. Geol., 17, p. 39, figs. 1 to 6, 1909.

Type _Micrerpeton caudatum_ Moodie.

The genus _Micrerpeton_, of which the single species is described below,
was the first evidence of the occurrence of the Branchiosauria in America.
There have been three other genera referred to the Branchiosauria from
North American deposits, but there is good evidence that none of them
belong there. The genus Amphibamus was originally referred to the
_Xenorhachia_ by Cope (105, pp. 134-137) on account of the supposed
cartilaginous condition of the vertebræ and the absence of ribs. Later
he abandoned this order and placed the form in the Branchiosauria, where
it was retained by Zittel (642). Recently Hay has shown (316), and I am
able to corroborate his statement, that ribs are present in the species,
and that they are long and curved, not at all like the short ribs of
the true Branchiosauria. These long, curved ribs undoubtedly exclude
_Amphibamus_ from the Branchiosauria and indicate its close affinities
with the Microsauria. The genus _Pelion_ has also been referred to this
order on purely negative evidence (642, p. 375). This genus is excluded
from the Branchiosauria by the well-ossified condition of the limb bones,
in which the endochondral ossification is seen to be well developed, a
condition not found, so far, among the true Branchiosauria. The form of
the head and the elongate hind limb would also tend to exclude the genus
from the Branchiosauria. In the Branchiosauria the fore limb is usually
larger than the hind limb, the reverse of which is the case in _Pelion_.
The genus _Sparodus_, as it occurs in North America, is uncertain. It is
indicated by remains which are almost impossible of determination.

The genus _Micrerpeton_ may be distinguished from other known
Branchiosauria by the large size and anterior position of the orbits,
absence of a posterior table to the skull, the short, heavy limb bones,
the slender ilium, and the expanded, elongate, and laterally compressed
tail. The genus may be defined as follows: Small forms, the known
representative attaining a length of less than 2 inches; head broad and
short; sclerotic plates present; interorbital space less than the least
diameter of the orbit; occiput concave; pineal foramen in the line which
cuts the posterior edge of the orbits; teeth small, pleurodont denticles;
presacral vertebræ 20 or 21, of which probably 5 are cervical; 1 sacral;
ribs short, straight, and heavy, central; scapula ovoid; limbs stumpy and
heavy, fore limb exceeding the hind in size; endochondral ossifications
distinctly absent; tail long, expanded, and flattened, probably provided
with a thin expanded membrane; body covered with minute, ovoid or rounded
scales which are ornamented with concentric lines; color markings
vertical to the long axis of the body and abundantly present on the tail;
lateral-line organs represented by the dorsal and median lateral lines
on the tail, the sensory pits probably occurring in specialized darkened
scales. Coal Measures of Mazon Creek shales near Morris, Grundy County,
Illinois.


=Micrerpeton caudatum Moodie.=

  Moodie, Jour. Geol., 17, p. 39, figs. 1-6, 1909.

Type: Specimen No. 12,313, Walker Museum, University of Chicago.

Horizon and locality: Mazon Creek shales, near Morris, Illinois.

The species is represented by very complete remains (plate 2), which are
preserved on opposite halves of a nodule. The specimen was collected many
years ago by Mr. W. F. E. Gurley at Mazon Creek, but it has never before
been studied, although Dr. Newberry examined it and said in a note that
Professor Cope should see it. Unfortunately Cope did not see it and it
lay unknown for more than a quarter of a century. I am indebted to Dr.
Stuart Weller for calling my attention to the specimen, as well as for the
privilege of describing it.

The specimen is exceptionally perfect (plate 25, fig. 4). Nearly all the
skeletal elements are present, and the general contour of the body, the
character of the dermal covering, the color-markings, the lateral-line
system, and many other features of interest have been detected. Such
completeness of preservation is very uncommon even among the remains
obtained from this locality. In this case the entire form was preserved,
but the collector, in cracking the nodule, lost the chips containing the
feet, so that only portions of the limbs remain. It is thus impossible to
determine the phalangeal formula, but the feet were probably like those
of _Branchiosaurus amblystomus_ Credner, as given by Credner, to which
species the present form is closely allied and indeed must be placed in
the same family with _Branchiosaurus_, _Pelosaurus_, and _Melanerpeton_.

[Illustration: MOODIE                                            PLATE 2

Drawing × 3.5. of type specimen of _Micrerpeton caudatum_ Moodie, from the
Coal Measures of Mazon Creek, Illinois, showing skeletal elements, form
of head and tail, the lateral-line sense-organs, banded color-markings,
and ventral scutellæ. On the edges of the tail impression are indications
that in life the tail had a thin fold of skin above and below the fleshy
portion, much as in the larvæ of _Amblystoma_ at the present day.]

The remains here described represent a small, salamander-like form, and
they are among the earliest geological evidence of the group, which,
without doubt, gave rise to the modern salamanders. The parts preserved
in the specimen are: the complete outline of the head with most of the
cranial elements clearly distinguishable, as well as the black pigment
of the choroid; the entire vertebral column, including pits in the tail
region, where the vertebræ were without doubt entirely cartilaginous;
parts of the pectoral girdle; the ilium; the left humerus; the ventral
scutellation; the ribs of one side of the body and indications of ribs on
the other; portions of both hind limbs; and a complete impression of the
fleshy tail. On this impression of the tail are preserved small, horny
scales, transverse color-markings, and the distinct impressions of the
lateral-line system.

The bones of _Micrerpeton caudatum_, as in so many of the fossils from
this locality, have been replaced by a white, friable mineral which is
probably kaolin. The animal is preserved on its back and it is thus
illustrated from the ventral side. The entire length of the animal is only
49 mm., of which the tail occupies nearly half.

[Illustration: Fig. 13. Restoration of _Micrerpeton caudatum_, a
branchiosaur from the Coal Measures of Illinois. × 2.]

The head has much the same shape as in the species of Branchiosaurus
described and figured by Fritsch (251), Credner (181), and Thevenin (568).
The eyes occupy relatively the same position as in that genus. The orbits
are very large and broadly oval. Within the borders of the rim the stone
is blackened as though by the black pigment of the iris, such as Cope has
described in _Amphibamus_. Under a rather high power of magnification
the cranial bones are seen to be represented by mere flakes of white
mineral matter. The sutures separating the cranial elements are distinctly
preserved on the main half of the nodule.

The openings of the skull are five the two orbits, the two minute
nostrils, and the pineal foramen. A median suture separates the skull
into halves and the pineal foramen lies slightly anterior to the
posterior third of its length. The boundaries of the premaxillæ are not
distinct, but they are very small elements and form the inner border of
the nostrils, which are clearly indicated by bosses of stone. The nasal
element is nearly square and lies anterior to the frontal, which it
borders broadly. The parietal is about the same size as the frontal and it
apparently forms a portion of the inner border of the orbit, although this
is not assured. The parietal is elongate and unites posteriorly with the
postparietal. The postparietal, with the tabulare and the squamosal, form
the posterior boundary of the skull, and they are hence not unlike the
same elements in other Stegocephala. The pref rental forms the anterior
border of the orbit. The lacrimal has not been detected. The maxilla
is elongate and forms the antero-lateral border of the skull. The jugal
forms an important element in the lateral border of the cranium and joins
the quadratojugal posteriorly. The postfrontal is triangular and with the
postorbital forms the posterior border of the orbit. Both of the elements
are acuminate posteriorly, although the suture between them is indistinct,
and they inclose between their posterior acuminations an anterior
projection of the supratemporal. The squamosal has the usual relations and
borders the supratemporal laterally. The latter element forms the quadrate
angle of the cranium.

The entire length of the vertebral column is preserved, although
the nature and structure of its elements can not be determined. The
impressions of a few of the vertebræ show that some of the centra were
amphicœlous, but other than this nothing is definite. The cavities which
the centra occupied were filled by the white mineral matter and the force
of the blow which cracked the nodule destroyed the form of the mold. It is
possible that where the mineral matter has filled the cavities the centra
were osseous or partly cartilaginous, and where the cavities were unfilled
the centra were entirely cartilaginous. The length of the vertebral column
from the base of the skull to the last impression of a cartilaginous
centrum is 33 mm.

The number of centra between the sacral vertebra and the skull is 20 as
they are preserved, but there may have been one more, the atlas. Fritsch
has represented 21 in his restoration of _Branchiosaurus salamandroides_,
and this is a further indication of an affinity between the two genera,
although Credner has represented 26 presacral vertebra; in _Branchiosaurus
amblystomus_. The presacral vertebræ are thus seen to vary within narrow
limits, but the number of presacrals is near 20, and this may be taken
as typical. It is interesting to notice that in modern forms of the
salamanders the presacral vertebræ number about 20. There is but a single
sacral centrum in _Micrerpeton_. The sacral rib has not been detected, but
it is restored after the condition found in _Branchiosaurus_. The right
femur partially covers the sacral vertebra, and its structure can not be
determined. I count impressions of 17 caudal centra, of which at least
12 may have been partially ossified. In the cervical region there are
distinct impressions of transverse processes on at least 5 vertebræ, and
this number is assigned to the neck, although it is by no means certain
that this is the correct number. The neck was at least short, if we may
judge from the position of the remains of the pectoral girdle. No cervical
ribs are definitely determined. There is a short rib lying between the
fifth and sixth vertebræ, but to which it belongs is uncertain.

There are impressions of 10 ribs preserved on one side of the vertebral
column and one on the other side. They are short, straight, and heavy,
as are the same elements in _Branchiosaurus_. This character alone is
sufficient to place _Micrerpeton_ among the Branchiosauria, since no
such ribs are known in other groups of the extinct amphibians. The ribs
preserved lie next the seventh to the seventeenth vertebræ on the left
side, and there is one on the right side which may belong to either the
fifth or sixth vertebra. They are central in their attachment, and in this
they agree well with the mode of rib attachment in the modern salamanders.
All of the ribs are single-headed and are composed, for the most part,
of perichondral tissue. The position of the ribs in the matrix inclined
backwards, and, making a small angle with the vertebral column, is very
suggestive of the condition in _Branchiosaurus_.

The pectoral girdle is represented by three distinct elements of the left
side, which are identified as scapula, clavicle, and coracoid, following
the nomenclature given by Woodward (631), although Credner (186) would
name them otherwise. The scapula is represented by an ovoid fragment
lying next to the vertebral column. The clavicle was probably spatulate,
as in _Melanerpeton_, but the inner end of the element is not visible.
The coracoid is represented by its outer end only, and its inner pointed
extremity is not visible. The interclavicle has not been detected.

The humerus lies somewhat to one side of the pectoral girdle, as if
there had been a large amount of epiphyseal cartilage. Its position may
be due to post-mortem shifting, but there is little other evidence of
any movement after deposition. The humerus is a large, heavy bone in
comparison with the rest of the skeleton. It is expanded at each end, and
its ends show concavities, proving that the bone is formed principally
of perichondral tissue, as would be expected from such an early
Branchiosaurian. The endochondrium has not yet developed in this form,
which is evidently adult. There is no other element of the arm present.

There is but a single element of the pelvis preserved, a slender elongate
rod which is undoubtedly the ilium, since it has the usual position for
that element and is much too large for a sacral rib. It has much the same
shape as the ilium in the modern _Salamandra_, and is not expanded as is
the ilium of _Branchiosaurus_. This element, like the humerus, seems to
have been but a hollow cylinder of bone and undoubtedly had cartilaginous
ends, as in the ilium of the recent _Salamandra_. The two femora are
preserved nearly entire, the right one lying upon and partly obscuring the
sacral vertebra. The femur is much more slender than is the humerus, with
slightly expanded ends, and, like the humerus, shows the concavities at
the ends, indicative of the perichondral character of the tissue composing
it. There are two elements of the leg preserved more or less entire. The
larger bone may represent the tibia and the smaller the fibula. They both
present characters similar to those of the femur and humerus. They are
simple rods of bone tapering at the distal end. The feet have been lost,
though doubtless they were present at one time.

The ventral surface of the body, as in other members of the
Branchiosauria, was covered and protected by a series of small scutes
arranged in the regular chevron pattern. The form of the scutes and their
number can not be determined. The lines which represent them are, however,
distinct. Some of the scutes are missing and some of them are obscured
by lying over the vertebral column. They are all somewhat shifted to the
left. The lines are very small and close together. I count 16 of them
in a distance of 2 mm. In length the longest line preserved is a little
more than 4 mm., measuring from the point of the chevron. The lines
representing the scutes come to a point in a median ridge which is now
represented by a line. The dermal scutes on the abdomen were probably the
forerunners of the abdominal ribs of the reptiles (fig. 9).

The impression of the tail contains some of the most interesting features
in the entire specimen. Scattered over it and in places laid in mosaic
are impressions of small dermal scales, which may have covered the
entire body. In form the scales are ovoid, being half as wide as long,
and the markings on the scales partake of the nature of radiating lines,
much after the pattern of the sculpturing of the cranial bones in the
Microsauria. The scales are less than 0.5 mm. in diameter and their
character can only be ascertained under high magnification. Near the
middle of the tail there are preserved distinct transverse bands of
dark color, which are more or less evident throughout the entire tail
impression, but they are elsewhere not so distinct as in the central
region. The lines are evidently due to rows of pigmented scales, and in
all probability the animal's body was transversely striped.

The most interesting and important single structure discovered on the
specimen is the impression of the lateral-line system, which is clearly
evident as two dark lines on the impression of the fleshy part of the
tail. The sense-organs are represented by two longitudinal rows of
pigmented scales, one beginning at the tip of the tail, the other taking
its origin from the median line somewhat further forward. I am indebted to
Dr. Katashi Takahashi for calling my attention to the similarity of this
arrangement to that found in the recent _Necturus_. The arrangement and
disposition of the lines containing the sense-organs is practically the
same in the two forms. The median lateral-line takes its origin from the
extreme tip of the tail and is continued to the base, where the impression
is broken. The dorsal lateral-line has its origin rather abruptly from the
median lateral-line at a distance of 6 mm. from the tip of the tail. The
sense-organs were undoubtedly located beneath specialized pigmented scales
on the surface, and to this pigment is due the preservation of the lines.

The fact that the arrangement of the sense-organs of _Micrerpeton_
corresponds so exactly to the condition found in _Necturus_ is of
considerable interest. _Necturus_ alone among the modern tailed
Amphibia has the arrangement described for the lateral-line system of
_Micrerpeton_. All other forms of the Caudata, as also the larval forms
of the Salientia, have an arrangement of the lateral-line system which
is perfectly distinct from that found in Necturus, although the basis of
the same arrangement is found in all. In _Amblystoma_, for instance, the
median lateral-line is not present on the tail, and the dorsal line is
incompletely developed. The close similarity of the arrangement of the
systems of sense-organs in the two forms, _Micrerpeton_ and _Necturus_,
may be of genetic significance with regard to the latter form. The
lateral-line sense-organs are of a very fundamental significance, and
it is not at all improbable that the same arrangement of the lines has
existed from the Carboniferous period or earlier. We know that such
has been the case in a great many of the fishes. The ancestors of the
modern Caudata must have originated somewhere in the basal Carboniferous
or earlier periods, and, in the writer's opinion, the Branchiosauria
represent the ancestral group of the Caudata. This suggestion is by no
means new, since Baur and others have held the same view. This topic has
been discussed at length elsewhere (459) by the writer.

The relations of the form _Micrerpeton caudatum_ are readily determined.
The number of the presacral vertebræ, the form and position of the
ribs, the shape of the skull, the arrangement of the cranial elements,
the structure of the pectoral girdle and the character of the ventral
armature all clearly bespeak a close relationship with _Branchiosaurus_,
_Melanerpeton_, _Pelosaurus_, and other European branchiosaurian forms
from the Upper Carboniferous and Lower Permian.

The above-described species, with others given below, is the earliest
geological evidence of the Branchiosauria, since the oldest European
forms are from the Stephanian (Upper Carboniferous), which probably lies
somewhat above the horizon of the Allegheny series of North America. The
presence of the Branchiosauria in America is of considerable interest in
the bearing it has on the distribution and migration of the Paleozoic
animals. Knowledge of how the group came to occur in such widely separated
localities in approximately contemporary geological strata is an unsolved
problem of paleontology. It is possible that the piscian ancestors of the
Amphibia migrated across or along the borders of the seas and began the
amphibian phase of development independently in the two continents. That
evolution should, in this case, have followed almost exactly parallel
lines seems incredible.

Measurements.

                                    mm.
  Length of entire animal           49
  Length of head in median line      6.5
  Width of head at posterior border  8
  Length of orbit                    2.5
  Width of orbit                     2
  Interorbital space                 2
  Length of the vertebral column    33
  Length of the vertebral centrum
    in dorsal series                 0.5
  Length of trunk from base of
    skull to sacrum                 22
  Length of rib                      1.5
  Length of scapula                  3
  Maximum width of clavicle          2
  Length of humerus                  2.5
  Length of ilium                    1.5
  Length of femur                    2
  Length of tibia                    1.5
  Length of tail impression         21.5
  Width of tail impression at base   4


=Genus EUMICRERPETON Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 330, 1912.

Type: _Eumicrerpeton parvum_ Moodie.

The genus is established on three well-preserved specimens representing
nearly the entire anatomy. The generic characters are found in the very
broad posterior table of the skull, with its short length, reduction of
tympanic notch, and shortness of body. The body-length of _Eumicrerpeton_
(plate 5, fig. 1) is less proportionately than that of other closely
allied genera. Other generic characters are found in the sharp
postero-lateral angle of the skull, and it is to be distinguished from
_Micrerpeton_, especially, by the short, stumpy limb bones. The narrow,
elongate eye, placed close to the edge of the skull, is a character not
observed hitherto in the Branchiosauria. The genus is closely allied to
_Branchiosaurus_ of Europe.


=Eumicrerpeton parvum Moodie.=

  Moodie, Proc. U. S. Nat. Mus., 40, p. 430, fig. 1, 1911.

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 331-336, pl. 3, figs. 3
    and 4; pl. 4; pl. 5, fig. 1; pl. 6, figs. 1 and 2, 1912.

  Moodie, Amer. Nat., 44, pp. 367-375, figs. 1-4, 1910.

  Moodie, Science, n. s., XXXI, No. 789, p. 233.

Type: Specimen No. 803, Yale University Museum. Other specimens, No. 802,
Yale University Museum, and No. 4400, U. S. National Museum.

Horizon and locality: Mazon Creek shales, near Morris, Illinois.

The impression of the outline of the entire body is preserved (plate
3, figs. 1 and 2) in three specimens, and in all are found molds and
impressions of the alimentary canal, which, in one specimen (471), are
remarkably complete and instructive. The three specimens will be discussed
separately, since they show different features.

The impression of the larger animal (No. 803, Yale University Museum),
which is probably an adult, presents the following elements: the entire
skull, both humeri, impressions of posterior and anterior ventral
armature, portions of the alimentary canal, one femur, portions of a
fibula and tibia, and the entire impression of the tail, on which, as in
_Micrerpeton caudatum_, there occur two definite dark lines, one beginning
at the tip of the tail and running obliquely along the tail to where the
impression is broken at the anal region; the other beginning at a distance
of 4.5 mm. from the tip and running almost parallel with the median line.
These two lines undoubtedly represent the lateral-line system.

The skull is especially noted for its shortness and the great posterior
width, as well as for the almost entire absence of the tympanic notch.
The pineal foramen is located on a line with the posterior border of the
orbits. The eyes themselves are narrow and acuminate at each end, with a
pronounced convexity inwards and a flattening on the outer margin. They
are located on the very border of the skull, but relatively more posterior
than in _Micrerpeton_. No sclerotic plates are evident. The median suture
can be indistinctly observed running the entire length of the skull. The
sutures bounding the outside of the f rentals and the squamosals are
partially evident, but not satisfactorily preserved. The mandible is
represented by a mold which in wax impression shows short, stumpy teeth.

Posterior to the skull at a distance of a millimeter there are two sharp
impressions which may represent the anterior edges of the interclavicle
or they may be branchial elements. They are distinctly curved, however,
and probably represent portions of the interclavicle. A wax impression
does not show a discrete structure, but the boundaries of some larger
element. No other remains of the pectoral girdle can be discerned. The
humeri are short and relatively thick. Wax impressions show them to have
had truncate or slightly concave ends, thus indicating the absence or
slight development of the endochondrium. No other elements of the arm are
preserved.

The impression of an elongate femur and the heads of the tibia and fibula
of the left side are preserved.

The ventral armature is preserved in two small patches, and these show
the chevron-shaped rods to have been very fine much more delicate than in
_Micrerpeton_.

The body impression is very instructive and interesting, both in showing
the form of the body and because in it are preserved the larger portions
of the alimentary canal. The form of the body can best be discerned by
reference to the figures (plate 3, figs. 1 and 2; plate 5, fig. 1).

The portions of the alimentary canal preserved consist of the greater
portion of the stomach, three coils or loops of the small intestine, the
rectum, and a pit which undoubtedly represents the anal opening. The anus
is found at a distance of 16 mm. from the tip of the tail and is somewhat
removed from the body portion, as in modern salamanders. On each side of
the posterior end of the rectum there occur a pair of enlargements which
probably represent the oviducts at their posterior ends (fig. 15, C).

[Illustration: MOODIE                                            PLATE 3

  1. The larger specimen of _Eumicrerpeton parvum_ Moodie. × 1.

  2. The smaller specimen of _Eumicrerpeton parvum_ Moodie. × 1.

  3. Type specimen of _Erpetobrachium mazonensis_ Moodie. × 1.

  4. Type specimen of _Erierpeton branchialis_ Moodie. × 1.

  5 and 6. Type specimen of _Mazonerpeton longicaudatum_ Moodie. × 1.

  7. A copy of Cope's drawing of the type specimen of _Amphibamus
       grandiceps_ Cope. The original was destroyed by fire. × 3.

]

The tail impression is more acuminate than in _Micrerpeton_, but shows
the same structures as in that form, _i.e._, the lateral lines which have
already been mentioned. _Micrerpeton_ was a more rapid swimmer than the
present form on account of the greater development of the tail.

The second specimen of the species (No. 802, Yale Museum) shows much the
same character as the specimen already described, except that there are
impressions of small, blunt teeth on the mandible. The two humeri and the
femur of the left side are preserved and the interclavicle is represented
by an identical impression, as in the first-described specimen. The tail
impression, though similar in form, does not exhibit so much of the
structure of the lateral lines (fig. 15, B).

The matter of especial interest in connection with this second specimen
is the remarkably perfect preservation of the alimentary canal, which is
entire, except for the very anterior end of the œsophagus. The posterior
portion of the œsophagus, which measures 3.5 mm., is clearly preserved.
Its anterior end is thrown around posteriorly and indicates that this
end was loosened after death and became displaced before fossilization.
The length preserved may represent the entire œsophagus. The œsophagus
is constricted before it enters the stomach, which shows the usual
curvature found in modern salamanders. The stomach measures 6 mm. in
length by 2 mm. in breadth, and consists of a single enlargement as in
the modern _Amblystoma punctatum_. It increases in size somewhat toward
the pyloric end and then very gradually constricts to the pylorus. Three
divisions of the small intestine can be seen. The most anterior one,
corresponding to the duodenum, is segmented, as though the intestine had
been filled with food before interment. The remainder of the intestine,
corresponding to the ilium, is looped in the form of two figures =8= which
are superimposed, with the upper portions of the =8= at right angles to
each other. The rectum is clearly discernible, though its lower portion
is somewhat obscured by having the lower part of the upper loop of the
intestine lying over it. The anus lies at a distance of 1.5 mm. posterior
to the transverse line from, the upper end of the femur, and is quite well
back on the tail, as in modern salamanders. In this specimen also occur
two oval bodies which may be identified as the lower ends of the oviducts,
thus indicating, in all probability, that the animal was a female.

[Illustration: Fig. 14. Mazon Creek Amphibia.

  A. Third specimen of _Eumicrerpeton parvum_ Moodie, which exhibits
       the alimentary canal well preserved. × 2. Original in United
       States National Museum. _a_, anus; _f_, femur; _h_, humerus;
       _ic_, interclavicle; _in_, intestine; _m_, mandible; _or_, orbit;
       _st_, stomach; _t_, tibia and fibula.

  B. Type specimen of _Amphibamus thoracatus_ Moodie. Original in
       United States National Museum. × 2 (For description see P. 132.)

]

A dissection of several species of modern caudates has resulted in
the discovery that the adult condition of the alimentary canal of all
the species dissected (_Amblystoma punctatum_, _Necturus maculosus_,
_Diemyctylits torosus_, _D. viridescens_, etc.) is much more complex than
that exhibited by the specimen under discussion. A very near approach to
the condition found in _Eumicrerpeton parvum_ is found in an immature
branchiate individual of _Diemyctylits torosus_, 56 mm. in length, from
a fresh-water pond on Mount Constitution, on Orcas Island, Puget Sound,
Washington.

The similarity of the intestinal structure is of considerable importance
to our understanding of the relationship existing between the
Carboniferous Branchiosauria and the modern Caudata, and only confirms
other arguments, offered in another place (459), concerning their
immediate relationship.

The branchiosaurian affinities of the present species are almost too
evident to need discussion. The entire structure is essentially similar to
that of other genera of the order.

The third specimen of this species (No. 4400 of the U. S. National Museum)
is almost as perfectly preserved as were the other two specimens. The
skull structure, the intermediate position of the pineal foramen, the
epiotic notch, and the shape of the skull are essentially similar to the
described specimens of the species. The present specimen is more developed
than the other two and probably represents an adult. The alimentary canal
is perfectly preserved.

It is nearly half again as long as the smallest of the above-described
specimens, and the skull is proportionately longer and wider. There is
preserved also an impression of the anterior ends of both clavicles. The
right humerus is imperfectly preserved, as is also the right femur and
tibia; other than these the fossil is merely an impression.

The skull is so similar to those described above that additional
description is unnecessary. The pineal foramen is quite large and lies
on a line which cuts the orbits into equal longitudinal parts. The
interorbital space is about equal to the long diameter of the orbit.
Traces of sclerotic plates are observed in the left orbit, but they are
quite imperfect.

The alimentary canal (fig. 14_a_) is unlike the previously described
structures, in that the intestine is longer and more convoluted. It
lies in five longitudinal folds and ends in an enlarged cloaca, near
which there are impressions of two glands, or the posterior ends of
the oviducts, as was suggested for the Yale specimens. The creatures
undoubtedly fed on small plants and animals much as do the recent
salamanders.

Measurements of Eumicrerpeton parvum Moodie.

  No. 803 (222), Yale University Museum:          mm.
    Length of animal                             37.5
    Length of skull                               4.5
    Posterior width of skull at table             6
    Long diameter of eye                          1.75
    Transverse diameter of eye                   65
    Length of left humerus                        1.50
    Number of ventral armature rods in 1 mm      10
    Length of femur                               1.75
    Width across base of tail impression          3.5
    Length of tail from base to tip              17

  No. 802 (471) Yale University Museum:           mm.
    Length of animal                             30
    Length of skull                               4
    Posterior width of skull                      5
    Length of œsophagus                        3.5
    Length of stomach                             6
    Width of stomach                              1.33
    Estimated length of intestine                18
    Width across base of tail impression          2.5
    Length of tail from base to tip               7

  No. 4400, U. S. National Museum:                mm.
    Length of entire animal                      45
    Length of skull                               6
    Width of skull                                9
    Transverse diameter of orbit                  1.50
    Long diameter of orbit                        2.25
    Interorbital space                            2.50
    Diameter of pineal foramen                   50
    Length of body from back of skull to pelvis  22
    Greatest width of body                        9
    Length of tail                               16
    Width of tail at base                         5
    Length of humerus                             3
    Length of femur                               2.50
    Length of tibia (fibula?)                     1.75
    Length of stomach                             3
    Length of intestine (estimated)               5.6
    Width of intestine                            1

[Illustration: MOODIE                                            PLATE 4

  1 and 2. Vertebræ of _Spondylerpeton spinatum_ Moodie. × 1.

  3. Type specimen of _Mazonerpeton costatum_ Moodie. × 1.

  4. Type skeleton of Cephalerpeton ventriarmatum Moodie. × 0.9.

  5 and 6. The halves of the nodule containing a practically complete
       skeleton of Amphibians grandiceps Cope. × 1.

  Originals of above figures in the Yale University Museum.

]


=Genus MAZONERPETON Moodie.=

  Moodie, Kans. Univ. Sci. Bull., vol. VI, No. 2, p. 336, 1912.

Type: _M. longicaudatum_ Moodie.

The genus is distinguished from other known branchiosaurian genera by
the great length of the dorsal region, the elongate tail (plate 5, fig.
2), with its well-developed caudal ribs, the reduction of the tympanic
notch, the broad nature of the scapula, the elongate interclavicle, and
the slender ilium. The number of dorsal vertebræ is identical with that of
_Branchiosaurus_ of Saxony.


=Mazonerpeton longicaudatum Moodie.=

  Kans. Univ. Sci. Bull., VI, No. 2, p. 337, pl. 3, figs. 1-2; pl. 7,
    fig. 3; pl. 10. 1912.

Type: Specimen No. 795 (1234), Yale University Museum.

Horizon and locality: Mazon Creek shales, near Morris, Illinois. (Plate 3,
figs. 5 and 6.)

The remains consist of the following elements: an incomplete skull; nearly
the entire vertebral column, consisting of cervical, dorsal, sacral, and
caudal vertebræ, 36 in number; several ribs preserved on each side of
the vertebral column; a portion of the ventral armature; the scapulæ; a
clavicle; the interclavicle; both humeri; the radius and ulna of one side
and the ulna of the other; portions of both hands; the ilium of the right
side; both femora, and a partial impression of the left tibia.

The skull is, unfortunately, very poorly preserved. Enough remains,
however, to determine the essential characters. The skull bones, unlike
any other American branchiosaurian, have an ornamentation consisting of
sharp pits and elevations which in places have a quincuncial arrangement
and in others take the form of definite lines of pits or tubercles similar
to the condition found in many of the Microsauria. The orbits are large
and are situated back of the median transverse line of the skull. They
are almost circular in form and contain 6 elongated sclerotic plates very
closely arranged around the borders of the right orbit. The plates are
twice as long as wide. The interorbital width is 1.25 times the transverse
diameter of the orbit.

Not many of the sutures of the skull are discernible. Portions of
the frontals, the nasals, the prefrontals, the parietals, and the
supratemporals can be identified. Their arrangement is shown in figure
14_a_. There is a decided posterior table to the skull, with truncate
posterior border. The tympanic notch is shallow, with its outer border not
so well protected as in _Branchiosaurus_.

The cervical vertebræ are incomplete, but their number was 4 or 5, as in
_Micrerpeton_. The structure of the dorsal vertebræ is also uncertain,
although the shape can be discerned. The vertebræ are short and thick,
very unlike the long, cylindrical vertebræ of _Cephalerpeton_. The heavy
transverse process is quite evident on the best preserved vertebræ. This
process recalls that described by Credner for the Saxony Branchiosauria.
Several of the vertebræ show the articulation of the ribs with this
process. The ribs of the caudal region recall very strongly those of
_Branchiosaurus_. They are quite heavy in the anterior caudal region and
then diminish rather rapidly to the point where the tail is broken and
lost.

The ventral armature is represented by a patch of chevron rods 21 mm. in
length. The rods take a very peculiar form, being short crescentic bundles
of fine rods, hair-like in appearance. In one of these bundles I count 5
smaller rods. The bundles are arranged in rows similar to the pattern so
characteristic of the Carboniferous Amphibia, as described elsewhere. The
patch of ventral armature preserved belongs to the abdominal region. A
single row of the crescentic bundles measures 11 mm.

Both scapulæ are preserved in their entire form. They are quite different
from those of any other genus, being broadly crescentic with a posterior
concavity and an anterior protuberance. The anterior surface of both
scapulæ is obscured. Vascular foramina occur near the base of both
scapulæ; there being three of them in the right scapula, arranged in
the form of an isosceles triangle. The morphology of these foramina is
uncertain. They have never been observed among the Carboniferous Amphibia,
and, so far as I am aware, they are entirely unknown among higher
vertebrates.

The temnospondylous Amphibia of the Carboniferous and Permian possess, in
the coössified scapula-coracoid, three foramina, very similar to the ones
in the present form, but they are confined to the coracoidal region and,
in the Branchiosauria, as identified by Credner, the coracoid is a free
element, although I have never been sure of its identity among American
forms. Williston has called these foramina the glenoid, the supraglenoid,
and the supracoracoid foramina (Journal Geology, XVII, No. 7). They are
not, however, to be correlated with the three foramina above mentioned,
since in the Temnospondylia the foramina belong with the coracoid and not
with the scapula. The condition of the Temnospondylia occurs in the bony
fish _Xiphactinus audax_ Leidy, and an analogous condition obtains in the
reptiles, as in the Mosasaurs and Dinosaurs.

[Illustration: Fig. 14_a_. Skeleton of _Mazonerpeton longicaudatum_
Moodie. _c_, carpus; _cl_, clavicle; _cr_, caudal ribs; _cv_, caudal
vertebræ; _h_, humerus; _f_, femur; _or_, orbit; _r_, radius; _sp_,
sclerotic plates; _sc_, scapula; _u_, ulna: _vs_, ventral scutellæ. From
Mazon Creek. Original in Yale University Museum.]

Near the outer edge of the right scapula there is a large fragment
preserved, which, I think, must be the misplaced clavicle. It is obscurely
triangular or, more exactly, spatulate. The interclavicle is represented
by fragments only, and seems to have had a narrow form.

The humeri recall those of _Micrerpeton_. They are somewhat elongate
and apparently cylindrical in their normal condition, although somewhat
flattened in the fossil. The shaft is considerably constricted at the
middle and the ends are expanded, in which expansion the lower end
exceeds. The ends are abruptly truncate, indicating a small amount of
endochondral ossification or its entire absence.

The mesopodial elements, unlike what is described for _Cephalerpeton_,
are quite dissimilar in form, recalling the condition in _Mesosaurus
brasiliensis_ McGregor. The larger element is, apparently, the ulna.
It has the lower end greatly expanded and the shaft is curved outward,
resembling very much a reptilian ulna. The radius is much smaller than the
ulna, lacks the lower expansion, and is shorter by 1 mm.

The carpus is represented merely by a blank space, with evidences of
impressions of cartilage in the sandstone. The hand of the right side
contains 4 phalanges. There are 2 phalanges preserved in the first digit,
including a sharp-pointed terminal phalanx, and the second digit has only
the metacarpal. The third has the metacarpal and the first phalanx, which
does not differ in form, but only in size, from the metacarpal. The fourth
digit contains only the metacarpal. Of the left hand there are portions
of 3 digits preserved, including 3 metacarpals and a phalanx, which in
structure are not different from those of the right hand.

The ilium of the left side is preserved, apparently entire. It is elongate
and cylindrical, its upper end adjoining the twenty-eighth vertebra.
The head of the femur lies close to the lower end of the ilium, so that
that element must have been suspended in the flesh, much as in modern
salamanders. It could not have been of much use as a support for the
body. The form of the femur is not unlike that described for the humerus,
save that its lower end is smaller than the upper, while in the humerus
the extremities are of equal diameter. A portion of the right femur is
preserved, extending in an opposite direction to the left.

Measurements of the Type.

                                               mm.
  Length of entire specimen                   64
  Length of portion of skull preserved         6.5
  Posterior width of same                      7
  Width across orbits                         11
  Long diameter of orbit                       3
  Transverse diameter of orbit                 1.75
  Interorbital width                           4.75
  Length of dorsal vertebræ                   48
  Length of caudal series                     11
  Length of anterior dorsal centrum            2
  Length of anterior dorsal rib                4
  Length of anterior caudal rib                1.75
  Length of scapula                            5
  Greatest width of scapula                    4.25
  Probable length of interclavicle             6
  Width of same                                3
  Length of clavicle                           4.5
  Width of same                                1.5
  Length of right humerus                      6
  Distal width of same                         2
  Length of ulna                               3.25
  Distal width of same                         1
  Length of radius                             3
  Width of carpal space                        2
  Length of metacarpal                         1.74
  Length of first phalanx                      1.75
  Length of distal phalanx of right hand        .35
  Number of chevron rods in 1 mm.              4
  Length of ilium                              2.25
  Length of femur                              4
  Proximal width of femur                      1.50


=Mazonerpeton costatum Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 341, pl. 2, fig. 3; pl.
    8, fig. 4; pl. 9, fig. 2; pl. 10. 1912.

The remains on which the present species is based are inclosed in a much
fractured nodule. The parts of the animal which have been identified
are: a part of the skull and left mandible, two clavicles, a humerus,
impressions of several vertebræ, a portion of the dorsal region of the
body with several ribs, two portions of the caudal region with several
ribs and unidentified fragments. (Plate 4, fig. 3.)

The animal, from the shape and form of the ribs, is undoubtedly a
branchiosaurian, since short, heavy, straight ribs have not yet been
found to be associated with other than branchiosaurian structures. It
is placed in the genus Mazonerpeton on account of the structure of the
pectoral elements, the form of the humerus, and the length of the tail,
all of which agree in structure with _Mazonerpeton longicaudatum_. The
animal attained, perhaps, a length of 4.5 inches, while that of _M.
longicaudatum_ was about 3 inches. The tail in the present species is very
long and slender, more elongate than in any other known branchiosaurian.

[Illustration: Fig. 14_b_. Skeleton of _Mazonerpeton costatum_ Moodie. ×
1.5. Original in Yale University Museum, _dv_, dorsal vertebra; _ch_,
neutral spines; _cl_, clavicle; _cv_, caudal vertebræ; _f_, femur: _h_,
humerus; _m_, mandible; _rb_, rib; _sk_, skull; _v_, vertebræ.]

The part of the skull preserved is very unsatisfactory and, aside from the
fact that it seems to represent the under side of the left half of the
skull, little can be said. Three sutures can be observed, but what sutures
they are is undetermined. The left mandible lies crushed on the edge of
the skull and partially obscures what little there is of that structure.
The slightly curved impression, from which the bone has been either broken
or weathered, measures 13 mm. in length by 3 mm. in posterior diameter by
1 mm. in anterior diameter. These measurements show the element to have
been slender and pointed anteriorly.

Very little accurate information can be derived from the study of the
vertebral column of the specimen, nor can the dorsal vertebral formula
be made out, since only a portion of the length of that region is
preserved and only a few rather indefinite impressions can be discerned.
These impressions show the vertebræ to be short and higher than in most
Branchiosauria.

The caudal series is represented by two sections, one of which is,
apparently, from near the base of the tail, judging from the size of the
caudal ribs preserved; the other is from near the tip of the tail, and
shows the constituents to have been long and slender. Ribs are apparently
absent on this section. The position of the two caudal sections shows
that when the animal died it was coiled up much like a snake, so that in
the fractured nodule three sections of the body are visible. The tail was
probably half as long again as the body.

The ribs throughout the body are short, heavy, and straight, with, in
the dorsal series, a lateral and a distal expansion which is taken as a
distinctive specific character. Judging from imperfect impressions in
the dorsal series, the ribs were attached to a transverse process of the
centrum, thus agreeing with other branchiosaurians in this respect. The
ribs show a progressive decrease in length from the cervical region to the
point of their disappearance on the tail.

[Illustration: MOODIE                                            PLATE 5

  1. A reconstruction of the possible appearance in life of the Coal
       Measures branchiosaurian, _Eumicrerpeton parvum_ Moodie, a
       small, primitive salamander, less than 2 inches in length,
       based on three specimens from the Mazon Creek Shales. The
       lateral-line organs are represented as dark bands on the tail,
       the sense-organs being, apparently, situated beneath specialized
       pigmented scales, to which is due the preservation of the lines.

  2. A restoration, natural size, of the branchiosaurian,
       _Mazonerpeton_, based on two specimens. The form of the animal
       is quite salamander-like. It is shown when about to feed on a
       specimen of _Acanthotelson stimpsoni_, which is said to be a
       brackish-water crustacean. The branchiosaur and crustacean may
       possibly have inhabited the same body of water.

]

The pectoral girdle is represented by two elements, one of which is
certainly the right clavicle, and the other is possibly the left clavicle,
though its form is somewhat distorted by pressure. Both elements are in
the form of an elongate spatula with the dorsal surface greatly concave
and the inner end acuminate.

The right humerus is imperfectly preserved, though the impression allows
one to gain an exact idea of its form. It lies under the right clavicle.
Its ends are truncate with a contracted shaft and expanded extremities;
the bone was apparently hollow.

[Illustration: Fig. 15.

  A. Impression of _Erierpeton branchialis_ Moodie. _bb_,
       basibranchial; _hyp_, hypohyals; _m_, mandible; _d_, body
       impression. × 3.

  B. _Eumicrerpeton parvum_ Moodie. _a_, anus; _f_, femur; _h_,
       humerus; _in_, intestine; _l_, liver; st, stomach; _r_, radius;
       _u_, ulna. × 3.3.

  C. Larger specimen of _Eumicrerpeton parvum_ Moodie. _a_, anus; _d_,
       dorsal lateral-line; _h_, humerus; _in_, intestine; _ml_, median
       lateral-line; _st_, stomach. × 2.6.

  D. Skeleton of _Erpetobrachium mazonensis_ Moodie. _cl_, clavicle;
       _h_, humerus; _r_, radius; _sc_, scapula; _u_, ulna. × 2.

  E. Rib of _Mazonerpeton costatum_ Moodie. × 2.5. Originals in the
       Yale University Museum.

]

In another nodule (No. 804, Yale Museum) there is a single bone preserved
which resembles, to a great extent, a rib of the present species (fig. 15,
E), although somewhat larger, and it has been provisionally identified as
such. The element is very slightly curved, but shows the expanded head of
the rib of this species.

Measurements of the Type of Mazonerpeton costatum Moodie.

  No. 800 (777), Yale University Museum:        mm.
    Length of portion of skull preserved        14
    Length of right clavicle                    16
    Width of right clavicle                      4
    Length of dorsal region represented         30
    Length of cervical rib                       8
    Length of dorsal rib                         6-5
    Length of caudal rib                         3
    Length of caudal portion of body preserved  55
    Length of mandible                          15
    Greatest width                               6
    Length of right humerus                     10
    Greatest width of humerus                    2

  No. 804 (332), Yale University Museum:
    Length of rib                               11
    Width of head of rib                         2
    Diameter of shall                            1


=Sparodus sp.= (?).

  Dawson, Phil. Trans. Roy. Sue. London, pt. II, p. 643, pl. 40, figs.
    52 to 56, 1882.

  Dawson, Proc. and Trans. Roy. Soc. Canada, XII, p. 75. 195.

Type: Specimen in the Peter Redpath Museum of McGill University.

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

The material on which the above determination is based was collected in
1878 by Sir J. W. Dawson in the coal formation at the South Joggins,
Nova Scotia. Nothing has been collected since that date that would give
additional information as to the nature of the form represented. I give
here Dawson's description of the remains:

"In the coaly matter or mineral charcoal at the base of tree No. 10
appeared a few fragments of an animal which may possibly belong to the
above-named genus of Fritsch, though I am by no means certain of this
identification or of the real nature of the animal.

"The skull is represented by a fragment of a maxillary or intermaxillary
bone, with blunt conical teeth. It is smooth or marked merely with
microscopic dots. There is also a fragment which may be a palatal bone
studded with minute teeth.

"A few vertebræ associated with the above bones are long and narrow, with
large zygapophyses and long neural spines. Length of body (i.e., of the
vertebra) about 3 millimeters.

"With these remains are a few bony scales different from those of any
other species found in these trees, and more resembling scales of Ganoid
Fishes. They are somewhat rectangular in form, enameled on the surface and
beautifully sculptured with waving lines.

"In the same trunk were found some teeth and bones referable to
_Hylerpeton dawsoni_, and it is not impossible that the remains above
referred to may have belonged to some creature devoured by that animal,
and which would not otherwise have obtained admission to the interior of
an erect tree. The tree itself had been removed by the sea, all but a
little of the base, and this was in a very unsatisfactory state, so that
doubt might even exist as to the limit between the deposit in the interior
of the tree and that under its base."

[Illustration: Fig. 15_a_. Type material of _Sparodus_, consisting of
_a_, a tooth (× 25); _b_, four of the smaller teeth (in maxilla?) (× 25);
_c_, three bony scales (× 5); _d_, fragment of a limb bone (× 2); _e_, a
vertebra (× 2). (After Dawson.)]



CHAPTER X.

ORDER CAUDATA DUMÉRIL, 1806. COAL MEASURES TO RECENT.


  Naked-skinned, elongate, tailed salamanders, mud-puppies, efts, newts,
  etc. External gills present or absent in adult condition, but always
  present in young. Limbs short, with usually 4 digits on hand and 5 on
  foot, but this is subject to much difference. Limbs never very stout.
  Carpus and tarsus cartilaginous. Skull roof without the postparietal,
  postorbital, and supratemporal. Skull elements never ornamented and
  never cut by the lateral-line canals. Vertebræ consisting of a single
  element; ribs short, attached to an elongate transverse process.
  Caudal ribs seldom present. Parietal foramen lacking. No ventral
  armature. Fresh-water inhabitants.


=Suborder PROTEIDA Cope, 1868.=

This order agrees generally with the Caudata, but presents one most
important feature of difference in the presence of the opisthotic. It is
this point which gives the Proteida its intermediate position between
the extinct amphibians and the recent species, and seems to indicate a
connecting line from the Coal Measures down to the present. The structure
of the hyobranchial arches sustains this view.

The hyoid apparatus differs from that of other adult Caudata and resembles
that of their larvæ in having three epibranchials, instead of one only.
The second basibranchial is also connected with the first, which is
not the case with the other Caudata. Three extinct genera are placed
tentatively in this suborder.


=Family COCYTINIDÆ Cope, 1875.=

  Cope, Bull. U. S. Nat. Mus., No. 1, p. 12, 1875.

The present family, as here defined, includes the forms whose structure
seems to ally them with the modern salamanders. The character on which
most dependence is placed is that of the branchial apparatus, lacking
in _Hyphasma_. The forms are all incompletely known and the family will
doubtless require revision on acquisition of additional material. Three
genera, each with a single species, are:

  _Cocytinus gyrinoides_ Cope. Linton, Ohio, Coal Measures. Based on the
  ventral impression of the skull, with the well-developed branchial
  apparatus.

  _Erierpeton branchialis_ Moodie. Mazon Creek, Illinois, shales. Based
  on impression of mandibles and branchial apparatus.

  _Hyphasma lævis_ Cope. Linton, Ohio, Coal Measures. Based on
  incomplete and obscure amphibian body, lacking limbs.


=Genus COCYTINUS Cope, 1871.=

  Cope, Proc. Am. Phil. Soc., 1871, 177.

  Cope, Geol. Surv. Ohio, II, pt. II, 360, 1875.

Type: Cocytinus gyrinoides Cope.

Vertebræ and ribs osseous; teeth on the premaxillary bone, none on the
maxillary; hyoid elements largely developed, an axialhyal with basihyal
on each side, closely united with the corresponding ceratohyal, at the
end of which is an element in the position of a stylohyal; hæmal or
basibranchials 3, the anterior 2, each supporting i pleural branchihyal,
and the third supporting one also, the first hæmal branchihyal on the
inner side of the ceratohyal, approaching the median line, and with
elongate pleural element.

The reference by Cope of this genus to the Caudata is one of the most
interesting facts connected with the Paleozoic Amphibia. He says: "The
present genus is, then, to be referred to the neighborhood of _Amphiuma_
and _Protonopsis_, but forming the type of another family" (123). He
regards the branchial apparatus as being more fish-like than that of any
of the modern genera. It is possible that _Cocytinus gyrinoides_ was a
larval branchiate and consequently aquatic form. It should be more fully
compared with _Erierpeton branchialis_ from the Mazon Creek shales when
better known, as well as with _Hyphasma lævis_ from the Linton locality.

All three of these forms are included, provisionally, under the Cocytinidæ.


=Cocytinus gyrinoides Cope.=

  Cope, Proc. Am. Phil. Soc., XII, p. 177, 1871.

  Cope, Trans. Am. Phil. Soc., p. 278, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, pp. 364-365, pl. xxxix, fig. 4,
    1875.

Type: Specimen No. 8613 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

[Illustration: Fig. 16. Obverse of _Cocytinus gyrinoides_ Cope, from
the Coal Measures of Ohio. × 2. _pmx_, premaxillæ: _mx_, maxilla; _m_,
mandible; _ah_, axialhyal; _h_, basal branchihyal; _ch_, ceratohyal; _bv_,
hæmal branchihyal; _b, bII, bIII, bIIII_, pleural branchihyals.]

Two specimens of this interesting amphibian are known, one of them fairly
complete (No. 2564, Am. Mus. Nat. Hist.). The type specimen consists
of the inferior bones of the cranium in a fairly complete state of
preservation, with the muzzle and its teeth; also 8 anterior vertebræ,
with their short recurved ribs.

The condition of the hyal elements in the type specimen is as follows: the
hæmal elements of the first branchial arch are partially concealed on both
sides of the ceratohyal. An expanded truncate face for attachment to the
axial element is visible on both sides, but the body of the bone is flat
and presents the edge of the specimen.

The first pleural element proceeds from just behind the axialhyal; it
is longer than the other pleural elements. A slender bone is visible
extending from the space between the ceratohyal and mandibular angle;
it may, therefore, pertain to the suspensorium of the jaw as well as to
that of the hyiod arch, or be squamosal as well as stylohyal. The second
hæmal bone is slender, but with an enlarged axial extremity; that of the
right side is not so well preserved as to be safely determined. The third
hæmal elements are the smallest, and originate immediately in front of the
occipital condyles and diverge outwards and backwards. They are little
curved, subcylindric, and slightly expanded at the extremities.

Of the pleural elements the first and second are little curved and the
first is marked by a pit or foramen on the under side near the distal end,
which is clearly visible on both sides of the specimen. The third and
fourth pleurals are more curved and the outer ends slightly expanded and
directed backwards.

[Illustration: MOODIE                                            PLATE 6

_Dendrerpeton acadianum_ Owen. Mandibles, parts of anterior
extremities, humerus, etc. Nearly natural size. Erect tree, Coal formation
South Joggins, Nova Scotia. Photograph by Dawson, published through the
courtesy of Dr. Arthur Willey. Original specimen in the British Museum of
Natural History.]

The obverse of the specimen (fig. 16) shows that the anterior axialhyal
is wedge-shaped. The lateral basihyals are massive. The second hæmal
branchihyal is dilated, fan-shaped distally, and supports two pleural
elements. The muzzle projects over the lower jaw and was rather broadly
truncate. The premaxillary teeth are cylindric and 6 in number on each
side. The maxillary bone is represented by a lamina at each lateral
extremity of the premaxillary. The mandibular rami are very stout, as
are also the ceratohyals. The vertebræ have possessed some apophyses,
apparently keel-shaped diapophyses. The ribs are slightly curved.

Measurements of the Type.

                            mm.
  Length of specimen        32
  Length of skull           12
  Posterior width of skull  11
  Length of premaxilla       5
  Length of mandible        10
  Length of axialhyal       3
  Length of postbranchial   4
  Width of vertebra         1
  Length of vertebra        3
  Length of rib             6

The other specimen of this species (fig. 16_a_) is interesting in having
40 consecutive vertebræ preserved, and 19 pairs of ribs attached in their
natural relations to the skull and hyal elements. There are a few hyal
elements preserved, but nothing is added to our previous knowledge. The
ribs are quite as in the type specimen, as are also the vertebræ. The
animal was apparently a slender, eel-shaped amphibian comparing favorably
with the modern _Amphiuma_ in this respect. There are no indications of
limbs or limb girdles.

Fig. 16_a_. Nearly complete specimen of _Cocytinus gyrinoides_ Cope, from
the Coal Measures of Linton, Ohio. Original in the American Museum of
Natural History. × 0.95.

Measurements (No. 2564, American Museum of Natural History).

                              mm.
  Length of entire specimen   113
  Length of skull              15
  Width of head posterior      15.5
  Length of vertebra            2
  Length of rib                 4


=Genus ERIERPETON Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 328, 1912.

Type: _Erierpeton branchialis_ Moodie.

The generic characters are found, first of all, in the presence of
hyobranchial arches which indicate its relationship to the formerly
described _Cocytinus gyrinoides_ Cope, from Ohio. The only other known
extinct genera of Caudata which possess, or at least have preserved, the
hyobranchial arches are the Jurassic _Hylæobatrachus_ from Belgium and
Lysorophus from the Permian of Texas. The present form is widely distinct
from both of these genera in the shape of the mandible and the form and
arrangement of the hyobranchial bars. The genus _Erierpeton_ finds its
closest ally in _Cocytinus_, in the family Cocytinidæ, which possibly
belongs in the order Caudata and the suborder Proteida of Cope.


=Erierpeton branchialis Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 329-330, pl. 1, fig. 3;
    pl. 2, fig. I, 1912.

Type: Specimen No. 801 (222) 5, Yale University, Museum.

Horizon and locality: Mazon Creek shales, near Morris, Illinois.

The amphibian remains designated by the above name consist of a distinct
mandible and some rather indefinite body impressions (plate 3, fig.
4). Three elongate impressions occur between the rami of the mandibles
(fig. 15, A), which, I suppose, must represent hyoid bones belonging to
the hyobranchial arches. The lateral elements are paired and the median
impression is straight and lies between the paired impressions of the
hyoids. The paired portions probably represent the hypohyals or hypohyals
plus the ceratohyals, and the unpaired portion of the first basibranchial,
according to the nomenclature of Wiedersheim (Comparative Anatomy of
Vertebrates, 1897, p. 86). If the impressions have been correctly
interpreted the present specimen is of very great interest, since it is
the first evidence we have of the hyobranchial arches in the Amphibia
of Mazon Creek, and the second in the Carboniferous of North America.
Dawson doubtfully identified (216) some elements of the Joggins Amphibia
as hyoids, but was uncertain as to their position. Cope described fully
the well-developed hyobranchial apparatus of _Cocytinus gyrinoides_ (123)
from the Coal Measures of Ohio. Among other Paleozoic Amphibia Williston
(614) has described branchial arches in the peculiar form _Lysorophus
tricarinatus_ Cope, from the Permian of Texas.

The form of the impression of the mandible in the present specimen is
unlike anything known to the writer among other Carboniferous or later
Amphibia. The rami are long, slender, deep, slightly curved, and pointed
anteriorly. The anterior symphysis was not a complete sutural union, but
was occupied partly by cartilage or other connective tissue.

There are no definite traces of the appendicular skeleton. The traces of
the body (fig. 15, A) indicate an elongated, rather slender animal, but
further than this nothing can be said in regard to its structure.

The occurrence of a typically caudate form in the Carboniferous is
unusual and complicates still further our understanding of the origin and
relationships of the early Amphibia.

Measurements of the Type.

                                           mm.
  Length of entire impression              50
  Length of mandible along median line     10
  Width of mandibular ramus                 9
  Length of basibranchial                   2.5
  Width of basibranchial                    0.75
  Length of hypohyal                        2.4
  Width of hypohyal                         1.5


=Genus HYPHASMA Cope, 1875.=

  Cope, Proc. Acad. Sci. Phil., p. 16, 1875.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 387, 1875.

Type: _Hyphasma lævis_ Cope.

"Vertebræ osseous, the posterior dorsals, and probably the caudals,
furnished with fan-like neural spines; limbs unknown--(?) wanting.
Thoracic shields present. Ventral armature, consisting of rhomboidal
scuta, forming packed rows arranged in chevrons, directed backwards, on
top of which are the usual rod-like scales arranged in packed chevrons,
with the angle directed forward.

"The general appearance of the type of this genus is that of a Ptyonius,
but the ventral armature is different from anything observed in the known
genera of this group. The larger external scuta are like those of the
species of Colosteus (Sauropleura), but their series have a different
direction. The inner chevrons are those of many other genera" (123).


=Hyphasma lævis Cope.=

  Cope, Proc. Acad. Sci. Phil., p. 16, 1875.

  Cope, Geol. Surv. Ohio., 11, pt. II, p. 387, pl. 37, fig. 4, 1875.

Type: Specimen No. 9023 (in counterpart), American Museum of Natural
History.

Horizon and locality: Linton, Ohio, Coal Measures.

  "In the only known specimen the vertebræ have low and squarely
  truncate neural spines near the head, and some distance anterior to
  the tail they are quite conspicuous and delicately line-grooved.
  The body is slender and probably limbless. The thoracic scuta are
  large and close to the head; the median is produced at both ends,
  but chiefly anteriorly while the lateral are narrow; all are without
  sculpture The head is seen from below. The mandibular rami are not so
  slender as in most species of _Ptyonius_, but are rather stout. They
  are a little incurved distally, so that the form of the muzzle is
  somewhat narrowed, but not produced. The teeth are not visible. Ten
  rows of the outer layer of scuta in 0.005 m." (123).

The specimen is very indistinctly preserved and the characters given
by Cope can not all be made out. It is puzzling to see just on what
he bases his conclusion. It is possible that the specimen is a poorly
preserved _Ptyonius_. The outlines of the vertebræ are so indistinct that
I am uncertain about them. In certain lights there appear to be regular
impressions which resemble the spines of the vertebræ of Ptyonius, but
they are doubtful. The skull appears totally distinct from any known
species of _Ptyonius_, but it is very imperfect. The condition of the
pectoral elements is very uncertain and I can not be sure that what Cope
described as thoracic "scuta" are such. The interclavicle, however, is
clearly preserved as a diamond-shaped structure. It is almost smooth, with
a few faint radiating lines near the base. It measures 5 mm. in greatest
breadth by 8 mm. in length.

Measurements of the Type.

                                            mm.
  Length of specimen as preserved           64
  Length of skull                           15
  Greatest width of skull                    8
  Width of body                              8
  Length of 7 cervical vertebræ             15
  Length of median thoracic scuta           10
  Width of same                              4
  Width of clavicle                          2
  Length of mandibular ramus                12



CHAPTER XI.

DEFINITION OF THE ORDER SALIENTIA, LAURENTI, 1768.

(World-wide distribution.)


  Naked, tailless Amphibia of compact form, and with usually procœlous
  vertebræ. Caudal vertebræ coalesced into a slender elongate piece, the
  urostyle. Two elements of the tarsus ossified and greatly elongated.
  Development by metamorphosis; gills never present in adult. Ilium
  greatly elongated.

The order is suggested in the Coal Measures by a single species, known
from a single poorly preserved specimen (plate 24, fig. 1). The form
_Pelion lyelli_ Wyman was the first known of the Linton Amphibia, and
its striking frog-like (123, 639) appearance was early noticed. There
is no assurance that the species belongs with this order, but since a
well-developed and highly specialized frog (480, 481) occurs in the Como
Beds (405) of Wyoming, it is not impossible that we may have in the
_Pelion lyelli_ a suggestion (460), at least, of the ancestral structure.
It is certain that the frogs have, in past ages, had a much greater length
of vertebral column than they possess at present, as is witnessed by the
coalescence of several vertebræ to form the urostyle. It is suggested that
the ancestral vertebral column is represented in _Pelion_.


=Family PELIONTIDÆ Cope, 1875.=

  Cope, Bull. U. S. Nat. Mus., No. 1, p. II, 1875.

The present family includes but a single species, that of _Pelion lyelli_
Wyman, first described in 1858 (640), from Linton, Ohio.

The family characters are to be found in the broad and obtusely rounded
cranium, in the frog-like scapular arch, the frog-like hind limb, and in
the form of the palate, so far as these structures have been preserved.

It has been suggested that the present form shows decided affinities with
the frogs of to-day and it may possibly be looked upon as the actual
ancestor of the living frogs. The length of the vertebral column would
seem to militate against such a relationship, since it is well known
that frogs have had a short vertebral column since the Jurassic (480,
481). But this is not a good argument, since the developing urostyles of
modern tadpoles show metameric fenestrations in the developing bone which
doubtless correspond to openings between the vertebræ. The notochord
of the tail is segmented, apparently through the influence of former
vertebral structure. At any rate, the suggestion is an interesting one
and, whether sustained or disproven, the present discussion is based on
the probabilities of the case.


=Genus PELION Wyman, 1868.=

  Wyman, Am. Jour. Sci. (2), XXV, p. 160, 1858 (_Raniceps_).

  Cope, Proc. Acad. Nat. Sci. Phil., 1868, 211 (_Pelion_, suggested in
    letter to Cope by Wyman).

Type: _Pelion lyelli_ Wyman.

  "The only specimen of the species exhibits an inferior view of a
  portion of the skeleton; and the obverse, on which the thoracic
  and abdominal armor could have been preserved, has not come under
  my observation. The specimen, however, does not exhibit any ribs,
  although the vertebræ are well preserved. As observed by Professor
  Wyman, the genus presents some points of similarity to the Anura
  (Salientia). The prolongation of the angles of the mandible is of this
  character, as well as the general form of the head. The bones of the
  forearm may be united as in the frogs, and the length and curvature of
  the femur are seen among these animals rather than the Salamanders.
  The form of the femur is different from that of _Amphibamus
  grandiceps_ Cope, which also differs in the presence of dermal scales
  and ventral scutellæ." (123.)

[Illustration: MOODIE                                            PLATE 7

_Hylerpeton dawsoni_ Owen. Above: Mandible, teeth, rib, and
bones of extremity. Below: Bones of pelvis and posterior limb and bony
scales. Nearly natural size. Erect tree, Coal formation, South Joggins,
Nova Scotia. Photograph by Dawson, published through the courtesy of
Dr. Arthur Willey. Original specimens in Peter Redpath Museum of McGill
University.]


=Pelion lyelli Wyman.=

  Wyman, Am. Jour. Sci. (2), XXV, p. 160, 1858.

  Cope, Proc. Acad. Nat. Sci. Phil., 1868, p. 211.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 390, pl. XXVI, fig. 1, 1875.

  Moodie, Pop. Sci. Monthly, LXXII, p. 562, fig. 1, 1908.

Type: Specimen No. 7909 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures. (Plate 24, fig. 1.)

This was the first species described from the Linton, Ohio, deposits.
It was made known by Dr. Wyman in 1857 at the meeting of the American
Association for the Advancement of Science for that year. The species was
subsequently studied by Cope. He merely confirmed Wyman's observations.
The following description is based on the descriptions of Cope and Wyman
and on my own study of the type specimen.

This is the most frog-like, in appearance at least, of all the Amphibia
which have so far been discovered in the Carboniferous. The skull
especially has a shape which is strikingly frog-like, and the long hind
limbs lend further likeness to the tailless forms. _Pelion_ may have
been a jumping creature, if we may judge from its long hind legs. Wyman
and Cope have both called attention to the frog-like appearance of the
specimen, and this is apparent at the first glance. It is probable that
the resemblance has some significance as to the ancestry of the Salientia,
and it may indicate the first step in the origin of the tailless Amphibia.
It is possible that the frogs began to be separated from the other
Amphibia during the Carboniferous. The first frogs we know are from the
Jurassic, where they are well-developed ranids. If _Pelion_ be a frog
ancestor, then the history of the group from the Coal Measures to Jurassic
is an unknown story.

The specimen is preserved on its back and it is thus impossible to tell as
to the structure of the skull. Cope was of the opinion that the depressed
areas on the sides of the elongate parasphenoid were the orbits, and if
so the resemblance to the frogs is much more striking. In the frogs there
is a strong process from the pterygoid which projects inward to meet a
corresponding process from the parasphenoid. This forms a heavy rod behind
the palatine vacuity. There is a heavy rod represented in the specimen and
a part of it is certainly the external process of the parasphenoid, but
whether it is to be interpreted as in the frog is an open question. The
outline of the cranium is partially obscured by the mandibles, but the
anterior part is represented by a raised line, as shown in figure 17. In
the anterior part of this space there are two ridges which may be tooth
ridges. If they are teeth there is a great similarity to the premaxillary
and vomerine teeth of _Necturus_, since the ridges are widely separated
at the median line and approximated distally, as they are in _Necturus_.
The mandible is preserved entire and its form is strikingly frog-like. Its
posterior angles project over the quadrate area and seem to have had an
upturned projection such as is found in the mandibles of the Crocodilia.

There are impressions of 20 vertebræ preserved, and they cover a little
more than half of the presacral region. There may have been 28 to 30
presacrals. The vertebræ, as preserved, are somewhat quadrate in outline
and constricted at the middle, as though they were of the typical
microsaurian type. No ribs are preserved.

[Illustration: Fig. 17. _Pelion lyelli_ Wyman, an amphibian from the
Coal Measures of Ohio, the supposed ancestral salientian. (After Wyman.)
× 0.75. _pmx_, premaxilla; _pv_, palatine vacuity; _m_, mandible; _sc_,
scapula-coracoid; _h_, humerus; _r-u_, radius and ulna; _f_, femur; _t_,
tibia.]

There is an impression anterior to the right humerus which may represent a
part of the pectoral girdle, but its form is so obscure that it can not be
determined. The pelvic girdle is entirely wanting in the specimen. Remains
of the fore and hind limbs are preserved. The arms are especially well
preserved and consist of a strong humerus, a separate radius and ulna, and
phalanges, the carpus having undoubtedly been cartilaginous, since there
are no traces of carpal bones. Wyman has figured a small ossicle (fig. 17)
which might be interpreted as a carpal, but it is further removed from the
carpal region than his figure shows and I would interpret it as a fragment
of a phalange, since the first digit seems to be turned aside over the
vertebral column. The right hand is but imperfectly preserved, but the
left hand is nearly entire. There are evidences of 4 digits, possibly 5.
The metacarpals are elongate and rather stout. The phalanges of the distal
series have been lost, so the phalangeal formula can not be determined.
On the whole, the hand has a very broad aspect and is not at all slender,
as in the majority of the microsaurians from the Coal Measures of Ohio.
It resembles in a great measure the broad hand of a toad and may thus be
indicative of a terrestrial life. The humerus is well developed and has
pronounced swellings, as though for the attachment of strong muscles.
These indications would favor the view of the animal being a land dweller.

The femur and a part of the tibia (?) of the right side are all there
is preserved of the hind limb. These elements show the leg to have been
quite long, though weaker than the fore limb. The femur has a large distal
articular surface. The fibula is, apparently, absent, though it may simply
be lost.

The genus _Pelion_ stands alone among the Carboniferous Amphibia. The
form can not be placed in the order Branchiosauria on account of the
well-developed limb bones and the large mandible. It may belong with
the Microsauria. I have placed it under the Salientia in the hope of
learning more about the early relatives of the tailless forms. There is
no assurance at all that it is even ancestral to the Salientia, but the
resemblances are striking.

The following gives the measurements of the type specimens:

Measurements of the Type Specimen.[B]

                                           mm.
  Length of specimen, as preserved         110
  Median length of the skull                24
  Width across the mandibular angles        25
  Greatest width of skull                   30
  Length of vertebral column from occiput
    to sacral region                        80
  Length of left humerus                    19
  Width of distal end of left humerus        5.5
  Length of radius and ulna                 11.5
  Width of distal end of radius              2
  Length of digit II, as preserved          16
  Length of digit III, as preserved         14
  Length of femur                           24
  Width of distal end of femur               4
  Length of tibia                           18

[Footnote B: The type specimen was collected in 1857 by Dr. John V.
Lauderdale, who presented it to Dr. J. S. Newberry.]



CHAPTER XII.

SUBCLASS LEPOSPONDYLIA ZITTEL, 1887. COAL MEASURES TO PERMIAN.

(Europe and North America.)


The group is here defined according to the English edition of Zittel's
Text Book of Paleontology, 1902, p. 125. "Notochord persistent and
enclosed in constricted bony cylinders, hour-glass-shaped in longitudinal
section. Teeth simple, conical, hollow." According to Zittel there are two
families, the Microsauridæ and the Aistopodidæ. The latter family is dealt
with under _Aistopoda_ (p. 76) and it is there shown that the group is
in no wise a valid one. The former family is regarded as an order and is
fully entitled to that rank. As defined here the subclass _Lepospondylia_
contains but a single order, the _Microsauria_.

Extinct, terrestrial, aquatic, or semi-aquatic amphibians; skull pitted
and grooved by lateral-line canals and by sculpturing marks, or the skull
may be smooth; teeth present on most of the palate bones; exoccipitals
cartilaginous or calcified, never completely osseous; sclerotic plates
sometimes present; skull of various shapes. Vertebræ with notochord
largely persistent, hour-glass-shaped; neural spines low or high, or
absent; ribs intercentral and single-headed, with an incipient tubercle
in some forms; vertebral column differentiated into dorsal and caudal
series; cervical series not clearly defined. Limb bones with well-ossified
perichondrium, endochondrium partly ossified; epiphyses absent; carpus and
tarsus (tarsus osseous in two species) cartilaginous; phalanges clawed or
not; digits 4 in hand and 5 in foot. Pubis sometimes calcified but never
osseous.


  Definition of the Order Microsauria Dawson, 1863. Coal Measures And
  Permian.

  (Europe and North America.)

  Lizard-like, sometimes longicaudate, stegocephalous, lepospondylous,
  ambulatory or legless amphibians; skull bones usually sculptured
  with pits and grooves; lateral-line canals well developed on skull
  bones; skull with horns from tabulare and supratemporals or without
  horns; branchiæ never persistent; sclerotic plates present; orbits
  usually well forward. Vertebræ hour-glass-shaped; endochondral
  bone weakly developed throughout skeleton, especially in vertebræ;
  notochord largely persistent; neural spines low and rudimentary or
  long, fan-shaped, and highly ornamented. Dorsal series of vertebral
  column variable; usually from 22 to 30; tail containing sometimes over
  75 vertebræ, or tail very short with 2 weakly developed vertebræ;
  caudal ribs present, in those forms with long caudal series the distal
  vertebræ sometimes exhibiting 2 pleurocentra. Ribs long and curved,
  always intercentral in position, single-headed, with at times an
  incipient tubercle. Pectoral girdle composed of scapulæ, clavicles,
  coracoids, and interclavicle. Pelvic girdle composed of osseous
  rod-like ilium, plate-like ischium; pubis cartilaginous, sometimes
  calcined. Limbs present or wanting or weakly developed, sometimes
  present in front and wanting behind. Radius and ulna and tibia and
  fibula free; carpus and tarsus usually cartilaginous; digits 4 in
  hand and 5 in foot, terminal phalanges sometimes clawed. Phalangeal
  formula for the hand 2-2-3-2, for the foot 2-2-3-4-3. Abdomen covered
  with dermal armature composed of osseous or corneous rods or scutes;
  overlapping scales, fish-like in appearance, sometimes present over
  the entire body; body also covered with lizard-like scales or naked.

The order Microsauria was established by Sir William Dawson in 1863 (208)
as a _family_ of "reptiles" for the reception of the genera _Hylonomus_,
_Hylerpeton_, _Smilerpeton_, and _Fritschia_. _Hylonomus lyelli_ is the
type species of the order. Dawson (216, p. 635) says of the species
_Hylonomus lyelli_ Dawson: "It is the type of the genus _Hylonomus_ and of
the family Microsauria." The forms which have been referred to the genus
_Hylonomus_, and hence to the order Microsauria, from the deposits of
Europe are discussed under _Hylonomus_.

The Microsauria have been regarded by the writer and others as being
ancestral in a sense to some of the later reptiles (469), but there seem
to be insuperable obstacles in the way of a direct derivation of the
reptiles from the Microsauria. One of these obstacles seems to be found
in the structure of the hand. In all Microsauria, so far as is known,
there is no evidence of more than 4 digits in the hand, while no true
primitive reptile possessed less than 5. The carpus of all true reptiles
is osseous, while that of the Microsauria is merely cartilaginous. It is
possible that the Microsauria stand in some such ancestral relation to
the later reptiles as the Crossopterygia (489_b_) do to the Amphibia.
The Microsauria had undergone adaptive modifications as to structure and
habit, so that they have paralleled many of the groups of reptiles, but
their structure is quite different. The evidence, as far as we can see
now, points to a close genetic relation between the reptiles and the
Microsauria, but that this relation is ancestral I, for one, am not ready
to say.

The Group _Aistopoda Miall_, 1873, is untenable.

The group _Aistopoda_ was established in 1873 as section IX by the
Committee of the British Association for the Advancement of Science, in
their "Tabular View of the Classification of the Labyrinthodonts." L. C.
Miall (449, 450) was the secretary of the committee, and the report was
published in two parts. Two genera were at that time attributed to the
Aistopoda, _Ophiderpeton_ and _Dolichosoma_, both described by Huxley from
the Coal Measures of Kilkenny, Ireland.

Fritsch (251, pp. 107-126) in 1883 refers to the group as "Familie"
and describes 4 genera and 9 species as belonging to the group. Zittel
(642, p. 383) refers to the group as "Familie" and places 5 genera in
it. Smith-Woodward (Vertebrate Paleontology, 1898, p. 129) refers the
Aistopoda to a suborder. In Eastman's translation of Zittel's Paleontology
the group is called a family, "Aistopodidæ." Lydekker (393, p. 205)
regards the group as a suborder. The writer (469) refers the Aistopoda
to an order. The group Aistopoda has been adopted by practically all
paleontologists and zoologists who have had occasion to refer to these
animals.

Lydekker (393) in 1890 defined the group as follows:

  "Body long and snake-like, without limbs, and apparently without
  pectoral or pelvic girdles. Vertebræ with elongated centra and aborted
  neural spines. Ribs slender, and barbed like those of fishes. Teeth
  smooth, without plications of the dentine. External gills probably
  persistent."

[Illustration: MOODIE                                            PLATE 8

_Fritschia curtidentata_ Dawson. Above: Bones of skull and
anterior extremity, and bony rods of belly. Below: Bones of pelvis and
posterior extremity. Nearly natural size. Erect tree, Coal formation,
South Joggins, Nova Scotia. Photograph by Dawson, published through the
courtesy of Dr. Arthur Willey. Original specimen in the Peter Redpath
Museum of McGill University.]

If now we take up a consideration of each of the characters mentioned
by Lydekker we find that the first one holds good for all examples of
the group. The second character, "without limbs," is not good. Species
of _Œstocephalus_, _Ptyonius_, _Molgophis_ all possess limbs; and
doubtless Ophiderpeton will be found to possess limbs also, since it
has a well-developed pectoral girdle. The limbs in all of these genera
are small. The third character, "apparently without pectoral and pelvic
girdles," is not at all a good character, since nearly every specimen of
some species and almost all species show evidences of pectoral girdles
and a few exhibit pelvic girdles. The fourth character, "vertebræ with
elongated centra and aborted neural spines," is not a good distinguishing
character, since _Amphibamus_, an undoubted microsaurian, possesses
the same vertebral characters. "Ribs slender, and barbed like those of
fishes" is a character which is common to several widely distinct genera.
All Microsauria possess long, slender ribs, and the barbed condition
is one which is possessed by only a few, _Thyrsidium_, _Ophiderpeton_,
etc., the so-called "barb" being merely a highly exaggerated tuberculum.
The teeth of nearly all Microsauria are smooth, so that the character
"teeth smooth" is not a good one for a group definition. It has not been
possible to examine any of the American specimens for the plication of
the dentine, since the forms are so rare and the fossils very fragile.
The last character, "external gills probably persistent," is certainly
not true for the American species, and the evidence for the European
species is negative. Fritsch described and figured (Fauna der Gaskohle,
Bd. I, 1883, p. 114, Tafeln 18 and 23) structures which he regarded as
supporting structures for the external branchiæ. He says in regard to
these structures:

  "Bei dem Umstande, dass sie von der Kiemengegend aus sich
  büschelförmig verbreiten und man ihren Contakt mit einer Art von
  Branchiæ constatiren kann, zweifle ich nicht daran, dass diese
  Stäbchen dem Kiemenapparate angehören. Bedenklich ist nur ihre
  grosse Zahl und das Vorkommen bis zum 16ten Wirbel und ich erwog
  die Möglichkeit, dass diese Stäbchen einem zarten Bauchpanzer
  angehören könnten. Da aber weiter im Verlaufe der ganzen Wirbelsäule
  nichts Aehnliches vorkömmt, so ist man gezwungen anzunehmen, dass
  _Dolichosoma_ sehr grosse lange Kiemenbüschel besessen haben muss."

John Samuel Budgett (79, p. 162), in his discussion of the "Structure
of the Larval Polypterus," refers to the above-described specimen of
"aistopodous Stegocephali," _i.e._, _Dolichosoma longissimum_ Fritsch,
and calls especial attention to the similarity of the external rod
of segmented cartilage on the hyomandibular of _Polypterus_ to this
structure, to which Fritsch has assigned a branchiate nature in
_Dolichosoma_. There is no doubt in the mind of the present writer,
however, that the rod of cartilage, referred by Fritsch to the gills,
can be other than scutellate rods of the ventral armature, these rods
belonging to the armature of the breast or throat. The evidence for this
conclusion is furnished by Fritsch himself (Fauna der Gaskohle, Bd. I,
plate 18, fig. 11), where all may read in the figure of the specimen the
facts of the case. There is quite evidently no justification for Fritsch's
conclusion of the branchiate nature of _Dolichosoma_. There is no evidence
of any gill-like structure in the American snake-like amphibians of the
Coal Measures.

Reviewing, then, the characters of the group which have been assigned by
various observers, it will be seen that there is but a single character
which holds good: "body long and snake-like." This is totally insufficient
for the retention of the group. I therefore propose to abolish the group
entirely from zoological classification. It is not even a family. It will,
however, be convenient to refer to the snake-like forms as "aistopodous."



CHAPTER XIII.

THE MICROSAURIAN FAMILY HYLONOMIDÆ, FROM THE COAL MEASURES OF NOVA SCOTIA.


=Family HYLONOMIDÆ Fritsch, 1883.=

  Fritsch, Fauna der Gaskohle und der Kalksteine der Permformations
    Böhmens, Bd. 1, p. 159, 1883.

  Lydekker, Cat. Fossil Reptilia and Amphibia, IV, p. 201, 1890.

The following characterizations of the family are those given by Lydekker
(393, p. 201) based on Fritsch (251): Body slender and lizard-like; skull
narrow, with smooth or faintly sculptured bones; neural spines of vertebræ
well developed, and long, slender ribs. Teeth smooth, or with grooved
summits. The whole body covered with sculptured scutes. Internal gills may
be developed.

Fritsch (251, Bd. I, p. 159) gives the following in his original
description:

  "Stegocephali von Baue schlanker Eidechsen mit schlanken langen
  Rippen. Wirbel amphicoel mit stark entwickelten oberen Dornfortsätzen.
  Schädelknochen glatt oder schwach verziert. Schuppen gross, verziert,
  den ganzen Körper deckend. Zähne glatt oder mit verzierte Spitze.
  Kiemenbogen bei einigen angedeutet. Mittlere Kehlbrustplatte
  unbekannt. Coracoidea ähnlich wie bei Branchiosaurus schlank, winkelig
  gebogen."

Fritsch includes the following genera in the family:

_Hylonomus_, _Hyloplesion_, _Smilerpeton_, _Seeleya_, _Orthocosta_, and
_Ricnodon_. The family includes the following species:

  _Hylonomus lyelli_ Dawson, Nova Scotia.
            _latidens_ Dawson, Nova Scotia.
            _multidens_ Dawson, Nova Scotia.
            _wymani_ Dawson, Nova Scotia.
            _fritschii_ Gein. and Deichm., Saxony.
            _geinitzi_ Credner, Saxony.
            _(?) pictus_ Fritsch, Bohemia.
            _wildi_ Woodward, England.
  _Smilerpeton aciedentatum_ Dawson, Nova Scotia.
  _Hylerpeton dawsonii_ Owen, Nova Scotia.
             _intermedium_ Dawson, Nova Scotia.
             _longidentatum_ Dawson, Nova Scotia.
  _Fritschia curtidentata_ Dawson, Nova Scotia.


=Genus HYLONOMUS Dawson.=

  Dawson, Quart. Jour. Geol. Soc. London, XVI, p. 274, figs. 14-18, 1860

  Dawson, Air-breathers of The Coal Period, p. 44, 1863.

  Dawson, Phil. Trans. Roy. Soc. London, 1882. pl. 11, p. 634.

  Credner, Zeit. d. deutsch. geol. Gesell., 1890 (IX Theil, die
    Stegocephalen und Saurier).

Type: _Hylonomus lyelli_ Dawson.

The genus _Hylonomus_ is a very important one from a taxonomic viewpoint,
since it was regarded by Dawson (216, p. 635) as the typical genus of
the order Microsauria, the most abundant group in the Carboniferous.
Unfortunately the species of the genus _Hylonomus_ are known only from
fragmentary remains. I have reproduced in plate 9 Dawson's figures of the
remains of _Hylonomus_ as published by him in 1891.

Dawson (216) gave, in 1882, the following definition of the genus
_Hylonomus_: "Form lizard-like, with the posterior limbs somewhat large in
proportion to the anterior. Size, small. Mandibular and maxillary teeth
numerous, small, conical, pointed. Palatal teeth minute. Abdominal scales
oval."

[Illustration: MOODIE                                            PLATE 9

_Hylonomus lyelli_ Dawson. 1, maxillæ and skull bones; 1_a_, sternal
bones; 2, mandible; 3, humerus, ribs, and vertebræ; 4, posterior limb;
5, pelvis; 6, caudal vertebræ. Nearly natural size. Erect tree, Coal
formation, South Joggins, Nova Scotia. Photograph by Dawson, published
through the courtesy of Dr. Arthur Willey. Original in the British
Museum.]

Credner (186), Fritsch (251, Bd. 1, p. 89, Taf. 12, figs. 1, 4, 15), and
Woodward (629) have referred remains of Microsauria discovered in the Coal
Measures or lower Permian deposits of Saxony, Bohemia, and Lancashire,
England, to the genus _Hylonomus_. There is much uncertainty as to the
validity of these references, due to the uncertain nature of the type of
Hylonomus. There are 4 American species of the genus: _Hylonomus latidens_
Dawson, _H. lyelli_ Dawson, _H. multidens_ Dawson, and _H. wymani_ Dawson.
All the species are from the Coal Beds at the South Joggins, Nova Scotia.


=Hylonomus lyelli Dawson.=

  Dawson, Quart. Jour. Geol. Soc. London, XVI, p. 274, figs. 14 to 18,
    1860.

  Dawson, Air-breathers of the Coal Period, p. 44, 1863.

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 635, pl. 39,
    figs. 1 to 14 and 27.

  Dawson, Acadian Geology, 3d ed., 1880, p. 370.

Type: Specimens Nos. R 443 to 445 in the British Museum (393, pt. IV, p.
223). Horizon and locality: Coal formation of the South Joggins, Nova
Scotia. This species is by far the most abundant (plate 9) in the erect
trees examined by Dawson. Its characters Dawson (216) defines as follows:

  "General form lizard-like, with the hind limbs rather larger than the
  fore limbs. Length when mature, 5 to 6 inches.

  "Head somewhat elongate; bones of skull smooth or with microscopic
  striæ, perfectly united, except at the parietal foramen. Occipital
  condyle double, and apparently bony. Teeth simple, conical, numerous,
  about forty in each mandible, and nearly equal, except that a few of
  the anterior ones are rather larger than the others. The teeth are
  anchylosed to the jaw in a furrow protected by an external bony plate.

  "Vertebræ with cylindrical bodies, slightly concave at the ends. When
  partly exfoliated they appear hour-glass-shaped, in consequence of
  the internal cartilage having the form of two cones attached by their
  apices. Zygapophyses conspicuous above; neural arches united to the
  bodies of the vertebræ, and with broad neural spines. Dorsal vertebræ
  with strong lateral processes. Caudal vertebræ apparently simple and
  cylindrical. Number of vertebræ in neck and trunk about thirty.

  "Ribs long and curved, with capitulum and tuberculum, cartilaginous
  within.

  "Anterior limb slender, humerus with distinct keel; radius and ulna
  separate; toes four or five.

  "Posterior limb with well-developed femur; tibia and fibula shorter,
  separate; toes five, somewhat long and slender.

  "Pelvis large, composed of ilium and ischium."

Interclavicle and numerous scutellæ are present. Upper surface protected
with imbricated horny scales. In front two rows of horny tubercles and
plates, with epaulettes composed of bristle-like fibers projecting from
the skin.

The animal possibly fed on insects, as is indicated by the coprolitic
matter associated with the remains of the species.

The following measurements are given by Dawson for the largest individual
discovered:

  Length of head                 about cm. 2
  Length of neck                   "    "  1.3
  Length of trunk                  "    "  7
  Length of posterior limb to heel     cm. 3
  Length of mandible                    "  1.8
    Teeth, 5 in 1 mm.
  Length of rib                        cm. 1.3
  Length of humerus                     "  1.4
  Length of femur                       "  1.8
  Length of tibia                       "  1.2
  Length of body of vertebra           mm. 2.5


=Hylonomus latidens Dawson.=

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 637, pl. 39,
    figs. 18-22.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, p. 74.

Type: Specimen No. 3061-1, Peter Redpath Museum, McGill University. The
British Museum (393, pt. IV, p. 224) also has a specimen, No. R 447.

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

Fragments of 3 specimens from 3 trees represent this species (plate 10).
It seems to have been of stouter build than _H. lyelli_, with the limbs
shorter in proportion. Its generic affinities are somewhat doubtful, as it
presents in some respects characters intermediate between _Hylonomus_ and
_Hylerpeton_.

Mandibular and maxillary teeth broadly conical, about 20 in each mandible
3 in 1 mm.; anterior mandibular teeth somewhat larger than the others, and
bent or hooked. Vomer or palate with minute teeth. Thoracic plate large.
Scales of abdomen oval, but somewhat narrow, and tending to be oat-shaped.

  Length of mandible (imperfect)     mm. 9
  Length of humerus                  mm. 7
  Length of vertebra                 mm. 2
  Length of tibia (?)                mm. 5
  Length of thoracic plate           cm. 1
  Length of six caudal vertebræ      mm. 8


=Hylonomus multidens Dawson.=

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. H, p. 637, pl. 39,
    figs. 23-26.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, p. 74

Type: Specimen No. 3061-2, Peter Redpath Museum, McGill University.

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

This animal is known only by portions of bones of the head and a few other
fragments. The scattered bones of the extremities are inseparable from
those of _H. lyelli_ occurring with it. As compared with that species, the
bones of this are smoother and more delicate. The teeth are more numerous
and slender. The crushed distal end of a femur or humerus found near the
skull indicates that the limbs were well developed.

                            mm.
  Length of mandible        11
  length of skull           15
  Length of femur            9
    Teeth, 5 to 6 in 1 mm.


=Hylonomus wymani Dawson.=

  Dawson, Quart. Jour. Geol. Soc. London, XVI, p. 277, figs. 27-29, 1860.

  Dawson, Air-breathers of the Coal Period, p. 52, 1863.

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 637, plate 39,
    figs. 15-17.

  Dawson, Acadian Geology, 3d ed., p. 378.

Type: Specimen No. 3061, Peter Redpath Museum, McGill University. There is
also specimen No. R 446 in the British Museum (393, pt. IV, p. 224).

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

As compared with the _H. lyelli_ the present species is smaller in size,
more elongated in form, had the teeth less numerous (about 22 in the
mandible), and shorter and more obtuse in form. There are 6 to 7 in I mm.

This species is much more rare than _H. lyelli_, but quantities of minute
bones, probably belonging to it, occur in the coprolitic matter. In one
specimen 38 vertebræ of this species were found partially associated,
indicating along, slender body. The body is covered with scales and
ventral scutellæ are present. Dawson questions whether this species may
not be the young of _H. lyelli_.

[Illustration: MOODIE                                           PLATE 10

_Hylonomus latidens_ Dawson. Skull, portion of skeleton, foot, scapula,
sternal bones, humerus, and rib, believed to belong to this species. Erect
tree, Coal formation. Nova Scotia. Nearly natural size. Photograph by
Dawson, published through the courtesy of Dr. Arthur Willey. Original in
the Peter Redpath Museum of McGill University.]

                        mm.
  Length of skull        8
  Length of mandible     5
  Length of rib          5.5
  Length of femur        6
  Length of humerus      5


=Genus SMILERPETON Dawson.=

  Dawson, Phil. Trans. Roy. Soc., London, 1882, pt. H, p. 634.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, p. 74.

Type: Smilerpeton aciedentatum Dawson.

The type species was originally referred to _Hylonomus_, but further
study induced Dawson to refer it to a new genus. Dawson gives (216) the
following characteristics of the genus:

  "Form somewhat elongated, and limbs short. Mandibular and maxillary
  teeth wedge-shaped, with cutting edges. Palatal teeth numerous, some
  of them large. Abdominal scales oval. A single species is known, _S.
  aciedentatum_, from the Coal Measures at the South Joggins, Nova
  Scotia."


=Smilerpeton aciedentatum Dawson.=

  Dawson, Quart. Jour. Geol. Soc. London, XVI, p. 275, figs. 19 to 23,
    1860.

  Dawson. Air-breathers of the Coal Period, p. 65, 1863.

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 638, plate 40,
    figs. 28 to 45.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, p. 75.

  Dawson, Acadian Geology, 3d ed., p. 376.

Type: Specimen No. 3061-3, Peter Redpath Museum, McGill University. The
British Museum (393, pt. IV, p. 224) also has a specimen, No. R 433.

The important characteristic (plate 12) is found in the form of the
mandibular and maxillary teeth, which are of a peculiar wedge-shape, being
broad and oval at the base and narrowed to a longitudinal edge at top.
Thus, when viewed from the side they appear narrow and blunt, but when the
jaw is broken across, and they are viewed from the rear or front, they
appear broad and sharp-edged. The effect of this arrangement is that the
jaw is armed with a closely placed series of chisels or wedges, giving an
almost continuous edge. At the end of the mandible some of the teeth are
longer and more conical.

Another important character is that the palatal and vomerine bones seem to
have bristled with teeth, mostly of very small size; but there are also
some larger palatal teeth, of which some are sharply pointed and others
blunt with furrowed points.

The vertebræ are of the same type as those of _Hylonomus_; but some which
appear to be caudal have a pointed spine above, indicating perhaps a
flattened tail. The ribs are short and stout.

The body seems to have possessed an interclavicle and ventral scutellæ.
Above it was, apparently, clothed with small tubercles and horny scales,
and to have had cuticular pendants like those of _Dendrerpeton_.

An additional species of this genus was apparently indicated by some
fragmentary remains, but Dawson thought best not to describe them as such,
since they might indicate only a young individual of the present species.

  Length of mandible           1.5 cm.
  Length of femur              1.5 cm.
  Length of humerus (?)        1.3 cm.
  Length of vertebra           3-5 mm.
  Length of rib                1   cm.
    There are 5 teeth in 2 mm.

[Illustration: Fig. 18. Skeletal elements of _Smilerpeton aciedentatum_
Dawson, from the Coal Measures of Nova Scotia. (After Dawson.) a, shaft of
femur, × 2; _b_, intermaxillary and teeth, × 25; _c_, sections of teeth, ×
25; _d_ and _e_, palatal teeth, × 25; _f_, femur, × 2; _g_, rib, × 2; _h_,
palate; _i_, caudal vertebræ; _j_, long palatal tooth, × 25; _k_, bony
scale.]


=Genus HYLERPETON Owen.=

  Owen, Quart. Jour. Geol. Soc. London, XVIII, p. 241, 1862.

  Dawson, Amer. Jour. Sci. (3), XII, p. 443, 1876.

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 634.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, p. 74.

  Dawson, Air-breathers of the Coal Period, p. 55, pl. vi, figs. 32-46,
    1863.

Body stout, with strong limbs. Mandibular and maxillary teeth strong, not
numerous, grooved at apex. Palatal teeth numerous, and some of them large.
Thoracic plate broad. Abdominal scales pointed or oat-shaped.

Type: _Hylerpeton dawsoni_ Owen.


=Hylerpeton dawsoni Owen.=

  Owen, Quart. Jour. Geol. Soc., XVIII, p. 241.

  Dawson, Air-breathers of the Coal Period, p. 55, 1863.

  Dawson, Acadian Geology, p. 380.

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 639, pl. 41,
    figs. 62-85.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1894, XII, p. 74.

Type: Specimen No. 3061-4, Peter Red path Museum, McGill University. There
are also specimens, Nos. R 441 and 442, in the British Museum (393, pt.
IV, p. 225). (Plate 7.)

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

Bones of skull slightly striated, but not sculptured as in _Dendrerpeton_.
Lower jaw with distinct ascending ramus or coronoid process, a feature
not known in any other of the Nova Scotia fauna, but observed by Cope in
_Brachydectes_. Teeth, 12 in each ramus of the mandible, bluntly conical,
slightly striated at the apex. Pulp-cavities large and longitudinally
striated at the sides, though the teeth are not folded. Maxilla furnished
with similar teeth, one of which near the front is larger than the others.
Palatal teeth numerous, small, conical, with a few large teeth at the
sides.

[Illustration: MOODIE                                           PLATE 11

_Hylerpeton longidentatum_ Dawson. Mandible and other bones. Nearly
natural size. Erect tree, Coal formation, South Joggins, Nova Scotia.
Photograph by Dawson, published through the courtesy of Dr. Arthur Willey.
Original specimen in the Peter Redpath Museum of McGill University.]

[Illustration: MOODIE                                           PLATE 12

_Smilerpeton aciedentatum_ Dawson. Mandible, portions of skull, scales,
and various bones. Nearly natural size. Erect tree, Coal formation, South
Joggins, Nova Scotia, photograph by Dawson, published through the courtesy
of Dr. Arthur Willey. Original specimen in the Peter Redpath Museum of
McGill University.]

Vertebræ short, cylindrical, well-ossified, with well-developed
zygapophyses and neural spines; ribs strong and much curved, with
well-developed division of the proximal ends; pelvis imperfect, but
apparently large, with broad ilium.

Humerus half the length of the mandible; radius half as long as humerus;
femur very large and stout, nearly as long as the mandible; leg bones and
phalanges correspondingly stout.

The thoracic plate (plate 7) is indicated only by some fragments. The
abdominal scales are narrow and pointed (oat-shaped), smooth externally
and with a ridge at one side within. The following are the dimensions of
the largest specimen:

  Length of mandible                  4.4 cm.
  Length of largest tooth             5   mm.
  Length of femur                     3.5 cm.
  Length of tibia                     2   cm.
  Length of humerus                   2   cm.
  Length of radius                    1.5 cm.
  Length of vertebra                  6   mm.
  Length of rib                       3   cm.
  Length of scales               5 to 7   mm.


=Hylerpeton longidentatum Dawson.=

  Dawson, Am. Jour. Sci. (3), XII, pp. 440-447, 1876.

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 640, pl. 42,
    figs. 86 to 109.

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1894, XII, p. 74.

Type: Specimen No. 3061-6, Peter Redpath Museum, McGill University. There
is also a specimen, No. R 440, in the British Museum (393, pt. IV, p.
225). (Plate 11.)

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

  Head much elongated, with the bones minutely pitted, and with delicate
  microscopic strife, but not sculptured. Mandibular and maxillary teeth
  long and acute, pointing backwards, with the apex of their inner
  sides finely striated; 20 or more in each ramus of the lower jaw;
  palatal bones with several long, slender teeth and many minute teeth.
  The mandibles found are not complete, but there are indications that
  there was an ascending process as in _H. dawsoni_, but less developed.
  The narrowness of the dentary bone is caused in part by the lower
  posterior edge being bent inward and by the posterior end being broken
  off above.

  Vertebræ short and stout, and apparently well ossified. Ribs long,
  with double head and much curved. Humerus longer than femur, which
  is short and stout, if the bone taken for it is rightly determined.
  Abdominal scales narrow, oat-shaped; thoracic plate large, broadly
  oval.

Measurements of Hylerpeton longidentatum Dawson.

  Length of mandible            4   cm.
  Length of vertebra            5   mm.
  Length of rib                 3   cm.
  Length of humerus             1.5 cm.
  Length of femur (?)           1.2 cm.
  Length of tibia               8   mm.
  Length of mandibular teeth    3   mm.
    6 to 7 teeth in 1 cm.


=Hylerpeton intermedium Dawson.=

  Dawson, Proc. and Trans. Roy. Soc. Canada, XII, p. 75, 1895.

Type: Specimen No. 3061-5, Peter Redpath Museum, McGill University.
Horizon and locality: Coal formation at the South Joggins, Nova Scotia.
This species is known only by the mandibles and portions of the skull,
which are rather shorter than those of adult individuals of the last
species. The extremity of the mandible and the cranial bones have the
same slightly waved surface as in the other species. Mandibles 3 cm. long
and the teeth, which are about 15 in each ramus of the lower jaw, are
simple, with large pulp cavities, those of the maxillary bone slightly
enlarging upwards, and intermediate in form between the long, slender
teeth of _H. longidentatum_ and the thick, obtuse teeth of _H. dawsoni_.

Coal formations, South Joggins, Nova Scotia, in erect tree, discovered by
P. W. McNaughton, 1893.


=Genus FRITSCHIA Dawson, 1882.=

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 634.

  Lydekker, Cat. Fossil Reptilia and Amphibia, pt. IV, p. 225, 1889.

Type: _Fritschia curtidentata_ Dawson.

  Body lizard-like; limbs large and well-ossified, mandibular and
  maxillary teeth conical, grooved at the apex. Abdominal scales slender
  and rod-like.

=Fritschia curtidentata Dawson.=

  Dawson, Phil. Trans. Roy. Soc. London, 1882, pt. II, p. 641, pl. 43,
    figs. 110-128.

  Dawson, Am. Jour. Sci. (3), XII, p. 444, 1876.

Type: Specimen No. 3061-7, Peter Redpath Museum, McGill University. There
is also specimen No. R 449, in the British Museum (393, pt. IV, p. 225).

Horizon and locality: Coal formation at the South Joggins, Nova Scotia.

Represented by 2 specimens (plate 8). Bones of the head very smooth, only
a few microscopic punctures. Teeth conical, somewhat obtuse, striated at
the inner side of the apices; there are about 30 in each ramus of the
mandible, and about 27 in the maxillary bone. Teeth implanted in a furrow.
Vertebræ short and well ossified, 3 in 1 cm. Ribs strong, curved, about 1
cm. in length. Limbs robust, the bones better ossified than in any other
known species from Nova Scotia. Toes of foot probably 5, central ones long
and slender. Interclavicle of moderate size and somewhat rounded. Ventral
scutellæ needle-like.

  Length of mandible (imperfect)     2.1 cm.
  Length of maxilla                  2   cm.
  Length of rib                      1   cm.
  Length of humerus                  2   cm.
  Length of femur                    2.4 cm.
  Length of radius and ulna          1   cm.
  Length of toe in foot              7   mm.
    8 teeth in 5 mm.



CHAPTER XIV.

THE MICROSAURIAN FAMILY TUDITANIDÆ, FROM THE COAL MEASURES OF OHIO AND
PENNSYLVANIA.


=Family TUDITANIDÆ Cope, 1875.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 357, 1875.

  Lizard-like microsaurians; cranial elements strongly sculptured
  with pits or grooves or almost smooth, with weak punctulations.
  Orbits usually well forward; squamosal sometimes excluded from the
  parietal; skull hornless; teeth pleurodont, conical and sharp,
  smooth or slightly plicate; clavicle of a triangular shape, which
  is characteristic of all the species; vertebræ well developed and
  phyllospondylous, the osseous portion being merely a hollow cylinder,
  hour-glass-shaped; ribs curved, long, attenuated and intercentral;
  digits clawed; ventral armature absent in all but a single species and
  the association of the species is doubtful; tail moderate in length.
  Three genera with 13 species included in the family. These species are:

  _Tuditanus punctulatus_ Cope, Linton, Ohio.
            _brevirostris_ Cope, Linton, Ohio.
            _longipes_ Cope, Linton, Ohio.
            _minimus_ Moodie, Cannelton, Pennsylvania.
            _walcotti_ Moodie, Linton, Ohio.
  _Erpetosaurus radiatus_ Cope, Linton, Ohio.
               _obtusus_ Cope, Linton, Ohio.
               _tabulatus_ Cope, Linton, Ohio.
               _minutus_ Moodie, Cannelton, Pennsylvania.
               _sculptilis_ Moodie, Cannelton, Pennsylvania.
               _acutirostris_ Moodie, Linton, Ohio.
               _tuberculatus_ Moodie, Linton, Ohio.
  _Odonterpeton triangularis_ Moodie, Linton, Ohio.

The association of these species in the one family is provisional and will
need revision on the acquisition of new and more complete material.


=Genus TUDITANUS Cope, 1874.=

  Cope, Trans. Amer. Phil. Soc., XV, p. 271, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, pp. 391, 1875.

Type: _Tuditanus punctulatus_ Cope.

The genus as here defined is a somewhat composite group and it is quite
probable that some of the species here included will have to be removed to
another genus when the anatomy of the forms is better known. The species
of the genus are all moderately small, the largest barely attaining a
length of 8 inches.

There are 5 species of Tuditanus thus far known. All of the species are
characterized by the possession of a peculiar triangular-shaped clavicle
with radiating grooves, and this has been taken as one of the distinctive
characters of the genus, as well as of the family. The structure of the
cranium where known is quite uniform among the different species. The
squamosal is quite large and the supratemporal is not always closely
joined to the parietal. The species are:

  _Tuditanus punctulatus_ Cope, Linton, Ohio.
            _brevirostris_ Cope, Linton, Ohio.
            _longipes_ Cope, Linton, Ohio.
            _minimus_ Moodie, Cannelton, Pennsylvania.
            _walcotti_ Moodie, Linton, Ohio.


=Tuditanus punctulatus Cope.=

  Cope, Trans. Amer. Phil. Soc., XV, p. 271, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 392, pl. xxxiv, fig. I, 1875.

Type: Specimen No. 110, American Museum of Natural History, where there is
also specimen No. 111.

Horizon and locality: Linton, Ohio, Coal Measures.

This species, together with the form, _T. brevirostris_, described on
p. 88, was used by Cope as the type of the genus _Tuditanus_. Cope
subsequently associated some reptilian remains from the Linton mines with
the type of _T. punctulatus_ and changed the generic term to _Isodectes_,
which was known by another species, _I. megalops_ Cope, from the Permian
of Texas. The remains associated by Cope with _I. megalops_ undoubtedly
represent a reptilian species and which has been described elsewhere
under the name _Eosauravus copei_ Williston. The species is of exceeding
interest because it is the _oldest known reptile_ and places the range of
the Reptilia down towards the base of the Pennsylvanian.

The species _Tuditanus punctulatus_ Cope was founded on well-preserved
remains of nearly the entire skeleton of a single individual. The bones
are represented by shining carbonaceous matter, and since both of the
slabs containing the impression were preserved, a great many characters
have been determined. The head, 1 fore-limb, and 23 consecutive vertebræ
with ribs are well defined, but of the pelvis and hind limbs nothing is
visible.

The cranium (fig. 19) is very similar to that of _T. minimus_, from
the Cannelton, Pennsylvania, slates. It is triangular in shape, with a
narrowed obtuse muzzle. The orbit of the left side is well defined and
lies well forward. It is oval in outline and its width is about two-thirds
of its length. The nostrils are small and are located well toward the tip
of the muzzle. The parietal foramen lies behind the median transverse line
which divides the skull equally.

The cranial elements are for the most part destroyed, but the outlines of
a few can be determined. Those elements which are preserved are ornamented
with a sculpturing of minute punctulations which, on the postfrontal,
assumes a radiating arrangement. The ornamentation of the other elements
consists of inosculating pits, but they seldom assume the form of ridges
or grooves. The bones of the premaxillary region of the cranium are
lacking. The first element which can be detected is the pref rental, which
occupies a position in front of the orbit. There seems to be space for
a lacrimal, but its outline is not distinct. The frontal can be readily
separated and is seen to be an elongate element occupying the median
region of the skull between the orbits. The parietal is apparently the
largest element of the cranial roof and the pineal foramen is located in
the anterior fourth of the median suture separating the parietal elements.
The form of the postparietal and the tabulare can not be determined, as
the greater part of this region is lacking. The squamosal seems to be
located well forward and is rather small, but has the usual relation of
this element. Only fragments of the other elements remain and nothing
can be said of their form. The mandibles of both sides are represented
by depressions, and they are ornamented with longitudinal grooves and
ridges. The teeth are not preserved, but there are evidences of the
maxillary teeth. These are minute and sharply conical. Just posterior to
the skull there is preserved the impression of a short, round rod which is
not definitely determined. It may be an element of the hyoid apparatus,
although it is rather stout for such. It does not have the relations
indicated by Cope in his figure (123, pl. XXXIV, fig. 1).

[Illustration: Fig. 19. Drawing of skull and skeletal elements of
_Tuditanus punctulatus_ Cope from the Coal Measures of Linton, Ohio. ×
1.5. _fr_, frontal; _ic_, interclavicle; _cl_, clavicle; _h_, humerus;
_ph_, phalanges; _par_, parietal; _pp_, postparietal; _tab_, tabulare,
supratemporal and squamosal; _u_, ulna; _r_, radius.]

There are three elements of the pectoral girdle preserved. These
undoubtedly represent the interclavicle and the clavicles. The
interclavicle is rhomboid in shape and is attenuated posteriorly. The
attenuation is abruptly truncate posteriorly and it is thus of quite
a different character from the acutely pointed interclavicle of _T.
minimus_. The clavicle has a somewhat semicircular form, but is not
attenuated at either end. It seems to be uniformly broad.

The forearm of the right side is preserved in part. The humerus is seen
to be a heavy, somewhat expanded element lying displaced with relation
to the pectoral girdle. It is greatly expanded at the ends. The ulna
presents characters similar to the humerus and only differs from it in
being shorter and less stout. The radius is not preserved. The carpus
is unossified and its position is occupied by a blank space. The digits
are represented by 4 metacarpals, and this may have constituted the
entire number of the fingers. The phalangeal bones preserved are a little
scattered. They are elongate with expanded ends.

Evidences of 23 consecutive osseous vertebræ are preserved. Their
character can not be determined, although Cope (123) describes them as
amphicœlous. This may be inferred to be the case, but I am unable to
verify his observation. In form the vertebra are subquadrate. The neural
spines are not evident. The osseous ribs articulate, apparently, between
the bodies of the vertebra. Cope figured them as intercentral. There are
22 or 23 pairs preserved. They are single-headed and the extremities are
attenuated. No traces of ventral scutellæ are present.

The entire length of the animal probably did not exceed 5 or 6 inches.
Its form was quite lizard-like and it was probably of an ambulatory type,
though it may have spent a part of its time in the old lagoon in which
its remains were finally buried. No traces of external gills have been
detected in this or any other Linton species.

Measurements of the Type of Tuditanus punctulatus Cope.

                                      mm.
  Length of entire specimen           94
  Median length of skull              22
  Width of skull at occiput           19
  Depth of mandibular ramus            4
  Length of the 23 vertebræ           61
  Length of interclavicle              6.5
  Width of interclavicle               4.5
  Width of the three pectoral plates  10
  Length of humerus                    8
  Width of humerus at proximal end     2.5
  Length of ulna                       6
  Width of ulna at proximal end        2
  Length of phalanx (metacarpal?)      2
  Expanse of longest ribs             16
  Length of rib                       10.5
  Width of rib                          .5
  Length of a vertebra                 2.5


=Tuditanus brevirostris Cope.=

  Cope, Trans. Amer. Phil. Soc., XV, p. 272, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 393, pl. xxvi, figs. 3, 4, 1875.

  Moodie, Bull. Amer. Museum Natl. Hist., XXVI, art. XXV, pl. lxiv, fig.
    4, 1909.

Type: Specimen No. 8609 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

This species was associated by Cope with the type _T. punctulatus_ in the
description of the genus. Represented by a portion of the skeleton of one
individual, the skull is preserved on one block, with a considerable part
of the anterior ribs, pectoral girdle, and vertebral column, although this
last is not clearly represented, but as in so many of the coal specimens
the bones are covered with a thin layer of carbonaceous matter which makes
it impossible to definitely determine the form.

The cranium is large in proportion to the size of the body. The skull is
in the form of a wide oval and is wider than it is long. The elements of
the skull were ornamented with a coarse sculpturing which partakes of the
nature of incomplete radiations on the squamosal region. The different
elements of the cranium can not be distinguished, although I think the
outlines of the parietal are indicated. The position of the nostrils is
well forward and they are slightly elongate transversely. The pineal
foramen can not be determined. The orbits are oval in shape and their
width is about equal to two-thirds of their length. The interorbital space
is greater than the length of the orbit. Cope's figure of this specimen is
not accurate, since he has the orbits drawn too far to the side. They are
located near the central line of the skull and resemble in some respect
those of the preceding species. Cope has described teeth in the maxillary
region, but I am unable to detect them. There are portions of two pectoral
elements which may represent a clavicle and a portion of the interclavicle.

The clavicle has much the same shape and practically the same
ornamentations as has the clavicle in _Tuditanus minimus_. The clavicle
preserved shows a somewhat triangular shape and is slightly acuminate
at the anterior end, as preserved, and obtuse at the posterior end. The
nature of the interclavicle can not be determined.

The vertebral column is represented by a line which Cope suggests (123)
may be the chorda dorsalis (notochord). Osseous vertebræ were probably
present, but their nature is obscured by the carbonaceous matter covering
them.

The ribs as preserved are long and curved. They are slender and attenuated
at the distal ends. They were probably single-headed, but whether their
articulation was intercentral or not can not be determined.

The other specimens which are referred to this species show nothing of
importance in the way of structure. They consist for the most part of
fragments which may or may not represent the species.

The species differs from the type of the genus (_T. punctulatus_) in the
possession of a broadly rounded muzzle. This character will also separate
it from other species of the genus. The sculpturing of the bones of the
cranium is coarser in the present species than in the type. The form
of the clavicle is different in the two species. The above-described
species seems to be more closely allied to the form described as Tuditanus
walcotti than to other species of the genus. I have been unable to detect
the presence of limbs, although Cope says they are present.

Measurements of the Type of Tuditanus brevirostris Cope.

                                       mm.
  Median length of skull               15
  Width of skull at posterior border   18
  Width of skull across orbits         11.5
  Length of orbit                       3
  Width of orbit                        2
  Interorbital space                    4.5
  Length of clavicle                    7
  Width of clavicle                     3
  Length of longest rib preserved       9
  Length of entire specimen            54

The material consists of the type specimen with counterpart and two
fragments which probably are to be associated with this species. Collected
by Doctor J. S. Newberry.


=Tuditanus longipes Cope.=

  Cope, Trans. Amer. Phil. Soc., XV, p. 210, 1874 (Sauropleura).

  Cope, Geol. Surv. Ohio, II, pt. II, 398, pl. XXVI, fig. 2, 1875.

Type: Specimen No. 1099 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The cranium of this species is quite unknown. The only genus with
which the specimen can be compared in the structure of the skeleton is
_Tuditanus_. From the other species of the genus the present form differs
in the presence of ventral chevron rods and the elongate character of the
limbs, as well as in the possession of large iliac bones, which, in the
only other species in which the ilia are known, are small and slender. It
seems best to locate the species in this genus for the present, although
it may eventually have to be removed to another group. Very little is
known of the main portion of the skeleton of the species of _Tuditanus_,
other than in _T. longipes_, so an exact comparison is impossible. From
all the species of Tuditanus thus far known the present species differs
in the elongate character of the limbs and in the presence of ventral
scutellation. There are three other species of Tuditanus in which the
limbs are known. These are: _T. walcotti_ Moodie, _T. minimus_ Moodie,
and _T. punctulatus_ Cope. In these three species the limbs are short
and weakly developed. From the other species of _Tuditanus_ the present
species maybe separated by its size principally, since nothing of the
bodies of the other species is known.

The body of the present species is elongate and slender, with a long neck
and probably a long tail. Ribs, as preserved, are 19 to 22, though there
may possibly have been more. They are moderately curved backwards, have
intercentral articulation, are attenuated at the distal extremity, and are
single-headed. The anterior ribs are stouter, with a widened upper portion
and attenuated distal part. The posterior ribs are more slender.

[Illustration: Fig. 20. Cope's drawing of Tuditanus longipes, from the
Linton, Ohio, Coal Measures. × 1.]

There are evidences of 28 vertebræ present. All regions of the vertebral
column are present and the dorsal region is preserved entire. The
cervical series is represented by the posterior vertebræ only. These are
very indistinctly preserved. The dorsal vertebræ are elongate and were
probably amphicœlous, although this has not been definitely determined.
They are expanded at each end, thus ending in a slightly raised rim. The
single-headed ribs articulate between the vertebræ. The exact number of
the dorsal series can not be ascertained, although this may have been
25. The spines of the vertebræ are not determinable, since the animal is
preserved on its back. The caudal vertebræ are represented by two patches
of the remains of what was once probably the entire series. Cope ascribes
70 mm. to the tail, but I do not find that much. The specimen may have
been mutilated since he studied it. The caudals are slender and, like the
dorsals, are expanded at the extremities.

The scapular arch is not preserved, but the pelvic arch is represented by
the two iliac bones in good state of preservation. These are short, flat
bones expanded at the anterior extremity, as preserved. They lie turned
a little to each side of the vertebral column and partially obscure the
femora. The iliac bones are quite characteristic of this form, since
similar-shaped elements have not been observed in any of the other
Carboniferous forms from the same deposit.

The greater part of the forelimb is preserved, although much of the hand
is missing. The humerus is an unusually elongate bone and lies somewhat
across the vertebral column. It is crushed flat and the ends are partly
destroyed. It shows evidences of expansion at the ends, although not a
great deal. It is much longer than the radius and ulna, which are of about
equal length. The ulna is larger than the radius and has expanded ends,
with the upper end more expanded than the lower and both ends slightly
truncate. The radius is a simple rod of bone and is but slightly expanded.
The carpus was evidently cartilaginous, since there is no evidence of
osseous material in its place. There is but one phalangeal bone preserved,
and, since this is displaced with reference to the ulna and radius, its
position can not be determined. It may have been a metacarpal. It is short
and expanded at the ends.

The hind limbs are represented by the two femora and the upper portion
of the tibia. The femur is almost as elongate as the humerus and is more
slender. It is not so much expanded as the humerus. Its ends appear to
have been cartilaginous and do not represent the well-formed articular
surfaces preserved in the _T. minimus_. The upper part of the tibia is
preserved, and appears to have been truncate.

If this species belongs with _Tuditanus_ it is of interest in that the
ventral chevrons are present. The species is particularly characterized by
the elongate limbs.

Measurements of the Type of Tuditanus longipes Cope.

                                                  mm.
  Length of vertebral column between pelvis and
    end of humerus                                 7
  Length of vertebral column anterior to humerus  18
  Length of caudals present                       42
  Length of humerus                               19
  Width of humerus                                 2
  Length of radius and ulna                       12
  Length of a vertebra                             3
  Length of ilium                                  7
  Length of femur, estimated                      18
    7 chevrons in 4 mm.


=Tuditanus minimus Moodie.=

  Moodie, Jour. Geol., XVII, No. 1, p. 56, fig. 10, 1909.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 23, pl. 8, fig. 2, 1909.

Type: Specimen No. 4555, U. S. National Museum.

Horizon and locality: Cannelton slates of Pennsylvania (Upper Freeport).

The species is represented by a nearly complete skeleton preserved on a
slab of slate from the Cannelton shales of Pennsylvania. The obverse slab
has been lost, which is very unfortunate, since there is no doubt that
the entire skeleton was originally present. The species is placed in the
genus Tuditanus on account of the close resemblance to the type form _T.
punctulatus_ Cope, although it is much smaller than that species.

The type specimen of the species did not attain a length of more than
3.5 inches. Its form is very lizard-like, but its structure is typically
amphibian. The form of the skull is especially similar to that of the
type species _T. punctulatus_, which it resembles in the narrow posterior
truncation of the skull, as well as in the anterior position of the orbits.

The skull is in the form of a narrow oval, sharply narrowed posteriorly
and truncate. The orbits are located well forward and their posterior
border lies in front of the line dividing the skull transversely into
equal parts. The interorbital space is greater than the diameter of the
orbit. Impressions of teeth are preserved on the premaxillæ and maxillæ;
there are 8 of them in a distance of 3 mm. The teeth appear to be mere
blunt denticles and were possibly pleurodont.

The elements of the cranium are very poorly preserved. It has been
impossible to determine all of the sutures. The bones of the premaxillary
region have been destroyed, but the arrangement of them was probably not
far different from that which obtains in other members of the genus. The
posterior boundaries of the nasals are preserved and prove this element
to have had an obtuse posterior border. The sutures bounding the frontals
are clear and show that they were small and that they formed a part of
the inner boundary of the orbits. The parietal is recognized as a large
element, apparently the largest in the skull. Together the parietals form
a wide oval inclosing, on the median suture, the circular pineal foramen.
The parietals are sculptured with coarse radiating grooves and ridges,
much after the manner of _Erpetosaurus radiatus_ Cope. The pittings
present on that form are, however, absent in _T. minimus_. The sutures
bounding the postparietal are tolerably well defined and these show that
element to have been rather large and quadrate, with the usual relations.
The tabulare is distinct, triangular, and small. It is produced into an
angle on the posterior border strongly recalling a similar condition in
_T. punctulatus_. The boundaries of the prefrontals and the upper borders
of the maxillæ are not clearly ascertained. The lacrimal has not been
detected. The post-frontal and postorbital form the posterior boundary
of the orbit, although all of the limits of the latter element have not
been definitely determined. The position of the supratemporal is well
assured, although its entire boundaries are not determined. It has the
usual relations and joins the parietal broadly. The jugal is broad and
widens posteriorly to join the squamosal, which, as usual, forms the
quadrate angle of the skull. The sutures bounding the quadratojugal and
the posterior end of the maxilla are not determined.

There are but two fragmentary vertebræ preserved and an estimate based
on the length of these remains gives about 30 presacral vertebræ. The
structure of the vertebræ preserved can not be ascertained, but the neural
spines appear to have been low and stout.

There are six elements of the pectoral girdle preserved. These are: the
six clavicles, the interclavicle, the coracoid of one side, and the two
scapulæ. The interclavicle is rhomboid in form and acuminate posteriorly.
It is sculptured with radiating grooves and ridges. It is quite different
from the same element in _T. punctulatus_, in that the base is acuminate,
not truncate. The clavicle presents much the same shape as does that
element in _Erpetosaurus tabulatus_. It is ornamented by a sculpturing of
radiating lines which take their origin from the lower external angle as
the bone lies in the matrix. The clavicle is somewhat triangular in shape
and lies close to the skull, but this close approximation of the pectoral
elements to the cranium is due probably to post-mortem shifting, since the
scapulæ are shifted backward. There can be little doubt, however, that
the pectoral arch was close to the cranium. There is an oval fragment
preserved on the left of the specimen which I take to be a portion of
the coracoid. The scapula is preserved entire on the left side and is
represented by fragments on the right side. It is almost semicircular in
form and narrows externally until it is somewhat fan-shaped. There appears
to be an ornamentation of lines on the surface of the bone. These lines
follow the contour of the anterior border.

The arm is preserved nearly complete on the left side, and the right
side shows the humerus and the forearm. The humeri are unusual in having
well-developed articular ends as though the endochondral tissue was
well developed. The humerus is expanded at the ends and it is larger at
the upper than at the lower end. The ulna is expanded at the proximal
extremity, but is more attenuated at the distal portion. It is shorter
than the humerus by about one-third of its own length. The radius is a
mere slender rod of bone and presents well-developed articular ends. It is
slightly shorter than the ulna. The carpus is unossified and its position
is represented by a blank space. There are phalanges of 4 digits preserved
and they are 4 in number. The phalangeal elements, like the other bones of
the extremity, have the articular surfaces prominent, with the terminal
phalanx claw-like.

There are no ribs nor traces of them preserved, and a conjecture as to
their character can not be hazarded, since they are known in but two other
species, in which they are slender and curved. There is no evidence of a
ventral scutellation, and so far as is at present known this structure
is absent from all of the species of the genus, or at least it is weakly
developed.

The ilium is all that is preserved of the pelvis. The bone itself has
disappeared and has left a depression which shows this element to have
been an elongate rod very similar to that described for _Micrerpeton_. The
sacral vertebra seems to be indicated by a depression between the iliac
depressions.

One hind limb is preserved nearly entire and the greater part of the other
is also preserved, although some of the phalanges are disturbed. The
femur is slender and more elongate than the humerus. It has well-formed,
rounded, articular ends. The tibia presents unusual characters in that
its ends are truncate, as though the cartilage composing its articular
surfaces was not so highly calcified as in the other limb bones. It
is somewhat expanded at the ends and is throughout its length broader
than the femur. The fibula, like the tibia, is a slender rod of bone,
although it is somewhat shorter than the tibia. The tarsus is unossified
and its position is occupied by a blank space. Portions of both feet
are preserved, but only one digit in the right foot is complete. The
metatarsals are elongate and slightly expanded at the ends. There are
4 phalanges present in the complete digit, which possibly represents
the fourth. The first digit is wanting, with the only terminal phalanx
preserved claw-like.

Measurements of the Type of Tuditanus minimus Moodie.

                                             mm.
  Median length of skull                     15
  Width of skull at posterior border         16
  Length of orbit                             3.5
  Width of orbit                              2
  Interorbital width                          2.5
  Length of clavicle                          6
  Width of clavicle, maximum                  3.5
  Length of interclavicle, estimated          5
  Width of interclavicle                      3.5
  Length of scapula                           3.5
  Width of scapula, maximum                   2.5
  Length of coracoid (?)                      2
  Length of humerus                           4
  Length of radius and ulna                   3
  Length of metacarpal                        1
  Length of ilium                             2.5
  Length of femur                             4.5
  Length of tibia and fibula                  3
  Length of foot                              3.5
  Length of metatarsal                         .75


=Tuditanus walcotti Moodie.=

  Moodie, Proc. U. S. Nat. Mus., XXXVII, p. 16, pl. 6, figs. 1, 2; pl.
    7; 1909.

Type: Specimen No. 4474, U. S. National Museum.

Horizon and locality: Linton, Ohio, Coal Measures.

A small species of Microsauria is preserved as a smooth impression on a
block of soft coal from Linton, Ohio. Nearly the entire form of the body
is discernible. The specimen is especially interesting and valuable as
exhibiting for the first time among the Linton forms the shape of the
body of the small microsaurians of the Tuditanus type. It differs so
markedly in the form of the skull from other species of the genus that
it is regarded as a distinct form, and the name _Tuditanus walcotti_ was
proposed for it as an expression of the writer's indebtedness to the
Secretary of the Smithsonian Institution for the vise of the material
among which the present form was included.

[Illustration: Fig. 21. A. Outline drawing of type of _Tuditanus walcotti_
Moodie, from the Coal Measures of Linton, Ohio, showing impression of body
and muscle at _M_. × 25. _cl_, clavicle; _fr_, frontal; _f_, femur; _h_,
humerus; _nos_, nostril; _or_, orbit; _par_, parietal; _rb_, rib; _pp_,
postparietal; _v_, vertebra; _pfo_, pineal foramen.

B. Left leg of second specimen of Tuditanus walcotti. × 3.]

The specimen includes, besides the body impression, the complete skull, a
right clavicle, with portions of the left, a left humerus, 12 cervical and
dorsal vertebræ, 10 pairs of ribs somewhat disturbed as to position, and a
portion of the mandible. There are no traces of ventral scutellæ nor body
scales in the smooth impression of the carbonized skin. One would expect
to find impressions of the ventral scutæ in this specimen if they were
present. Cope remarked on the apparent absence of scutellæ from members of
the genus _Tuditanus_ as they were known to him, and no contrary evidence
has since been brought to light. Until such evidence is forthcoming the
absence of scutes will be taken as one of the generic characters of the
genus _Tuditanus_. Under a magnification of 50 diameters the carbonized
skin shows as folds and wrinkles, like muscle fibers, in some places; in
others no traces of the muscular structure can be detected. The wrinkles
may be impressions of the internal musculature of the body-wall of the
abdomen. It is especially well preserved in the pelvic and pygal regions.
Sections of the coal were made, but nothing definite could be determined
as to the character of the impressions, as they were too poorly preserved
and the coal was too soft to bear much handling.

The specimen is preserved on the belly, with the dorsum of the skull
uppermost. It has been practically impossible to determine the arrangement
of any of the cranial elements except the f rentals, parietals, and
postparietals, which have the relations indicated in figure 21, A. A
median suture is clearly evident, with the pineal foramen well back in
this suture. The bones of the skull are marked with faint radiating lines.
It is in the form of the skull and the position of the orbits that the
specific characters are found, as follows: the backward position of the
eyes and the oval, pointed shape of the skull. The species is closely
related to _Tuditanus minimus_ Moodie, from the Cannelton slates of
Pennsylvania, and serves further to connect the forms from the Ohio and
Pennsylvania localities. It differs from the last-named species in the
position and form of the orbits, these structures being more oval in the
present form and placed further back. The shape of the skull differs also
in the almost entire absence of the posterior table. The median points of
the orbits occupy the line which bisects the skull, and the interorbital
width is less than the width of the orbit. The mandible is heavy and
appears to have borne sharp, pleurodont teeth.

The vertebral column is represented by little more than a mold of the
form of the vertebræ, so that little can be said of its character. The
individual vertebræ are short and hour-glass-shaped. The ribs are borne
intercentrally, as in all the microsaurians which have been studied from
the Linton deposits. The ribs are rather long and somewhat heavy, slightly
curved and expanded at the proximal end, as though an incipient bicipital
condition were present.

The right clavicle, which is preserved as an impression, is entire. Its
impression shows this element to have been ornamented on its ventral
surface with radiating grooves and ridges which started at the lower angle
of the bone. The element is distinctly triangular, which is characteristic
of the genus _Tuditanus_, so far as known. The fragment of the left
clavicle adds nothing to our knowledge of the element.

The left humerus recalls in a striking way that of _Tuditanus longipes_
Cope, and it was once entertained as a possibility that the present
form might be a member of that species, since the skull is lacking in
_T. longipes_. Sufficient specific differences were found, however, in
the ribs, which, in _T. longipes_, are very long, slightly curved, and
delicate, but which, in the present form, are comparatively heavy. Other
characters sufficiently diagnostic are found in the form assumed by the
vertebræ in the two forms.

Measurements of the Type of Tuditanus walcotti Moodie.

                                             mm.
  Length of specimen                         70
  Length of skull                            20
  Posterior width of skull                   14
  Width of skull, anterior to orbits         10
  Length of orbit                             4
  Width of orbit                              2
  Interorbital width                          3
  Length of clavicle                          9
  Greatest width of clavicle                  4
  Length of vertebral column, as preserved   50
  Length of a vertebra                        1.75
  Width of a vertebra                        50
  Width of body impression                   15
  Length of humerus                           6
  Median width of humerus                    50
  Width at end of humerus                     2
  Length of rib                               8
  Width of rib                               25

The above-described specimen was collected by Mr. R. D. Lacoe, of
Pittston, Pennsylvania, from Linton, Ohio.

A second individual (No. 4481, U. S. National Museum) of this species is
indicated by a rather poorly preserved specimen on a slab of soft coal
from the Linton mines. The following portions of the animal have been
detected and will be discussed: partial impression of the skull, with a
fragment of a minute jaw, in which are minute teeth; right clavicle; part
of the impression of the body; nearly entire left hind limb; impressions
of about a dozen vertebræ, very indistinct.

The impression of the skull is distinct only in a favorable light, and
even then the boundaries of the cranium are a little uncertain. For this
reason no representation of the form will be attempted. The sculpturing
on the parietals is, however, distinct enough to show relationship with
the previously described specimen, and the form of the body impression,
the absence of abdominal scutes, the shape of the clavicle and its
sculpture, and the proportions of the hind limbs all agree with the
characters which have been assigned to the genus _Tuditanus_. The fragment
of the jaw is interesting as giving the first information as to the
character of the mandible in the genus _Tuditanus_. It is very slender and
of uniform width as far as preserved. The teeth are short, blunt cones,
apparently pleurodont.

The clavicle is of the typical _Tuditanus_ form, with the sculpturing
lines radiating out from the angle. The impression of the body adds
nothing to that already described for the type specimen. The nearly entire
hind limb is of great interest as adding another example of the phalangeal
formula. The foot is almost perfectly preserved, and the formula was
probably 2-2-3-3-2. The endochondrium of the limb bones is not highly
developed. About a dozen vertebræ are represented by molds in the soft
coal, but nothing of their structure can be determined.

The sharp, reptile-like claws in which the toes end (fig. 21, B) recall
those of _Eosauravus_ and of _Tuditanus minimus_ Moodie. It is another
link in the chain of the suggested relationship between the microsaurians
and the early reptiles.

Measurements of the Second Specimen of Tuditanus walcotti Moodie.

                                        mm.
  Length of entire body impression      75
  Width across belly, maximum           16
  Length of skull                      ?17
  Posterior width of skull             ?14
  Length of fragment of jaw              4
  Width of fragment of jaw               1.5
  Length of tooth in jaw                  .25
  Length of clavicle                     8
  Width of clavicle, maximum             4
  Length of hind limb                   22
  Length of femur                        8
  Length of tibia (?)                    6
  Length of metatarsal                   2
  Length of first digit                  6


=Genus ERPETOSAURUS Moodie, 1909.=

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, p. 348, fig. 1, 1909.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 21, 1909.

Type: _Erpetosaurus radiatus_ Cope.

Skull stout, elements sculptured with radiating grooves, ridges, and
pits; orbits large and usually placed far forward; occiput sometimes
with posterior table; skull more or less rounded; lateral-line canals
consisting of supraorbital, suborbital, jugal, and temporal canals,
the last two uniting to form a circular canal in one species; clavicle
triangular, sculptured like the skull.

Our knowledge of the genus is confined to the skull. The genus was
established for certain members of the genus Tuditanus and other forms
which have been recently described. The species of the genus are: _E.
radiatus_ Cope type, _E. tabulatus_ Cope, _E. tuberculatus_ Moodie,
_E. obtusus_ Cope, _E. minutus_ Moodie, _E. acutirostris_ Moodie, _E.
sculptilis_ Moodie. All of the species are from the Linton, Ohio, Coal
Measures, with the exception of _E. sculptilis_ and _E. minutus_, which
are from the Cannelton, Pennsylvania, slates.

The position of the genus as to family is a little uncertain, since family
characters are not yet well understood among the Carboniferous forms on
account of the lack of information as to the structure of the animals. If
we take the absence of the ventral scutellæ as a family character, the
genus will be in the family Tuditanidæ, but the evidence on this point is
negative. For the present we may place the genus only provisionally in the
family Tuditanidæ. The arrangement will undoubtedly require revision later.


=Erpetosaurus radiatus Cope, 1874.=

  Cope, Trans. Amer. Phil. Soc., XV, p. 273, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, pp. 394-395, pl. xxvii, fig. 1;
    pl. xxxiv, fig. 3; text-fig. 10, 1875.

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, p. 348, pl. lxii, fig. 1,
    1909.

Type: Specimen No. 8600 G, American Museum of Natural History. Locality
and horizon: Linton, Ohio, Coal Measures. (Plate 25, fig. 1.) Cope
originally described this species from a portion of a skull. He (123)
characterized the form as follows:

  "The marked character of this form is seen in the very anterior
  position of the orbits and the contraction of the muzzle. The orbits
  are large and are separated by a little more than their own diameter;
  their posterior border is in front of a line measuring the anterior
  third of the length to the supraoccipital crest, and nearly to the
  line marking the fourth of the length to the quadrate region. The
  posterior outline of the skull is deeply concave, the quadrate angle
  projecting beyond the occipital condyles."

The base of the specimen is broken and there is no place for the occipital
condyles. Unless the specimen has been mutilated since Cope studied it,
the occipital condyles are not present.

The restoration of the skull given in figure 22, B varies but little from
that given by Cope in 1875. The elements are practically as he represented
them.

The premaxillæ are small and lie in the usual relations to the other
elements. Minute conical teeth are present as impressions. They are quite
similar to the teeth found in other Microsauria. The nasals are nearly
square and form the inner boundary of the somewhat oval nostril, which is
represented by a depression in the coal. The frontal is elongate. It is
about twice as long as wide. It forms a portion of the inner border of the
orbit, the remainder being made up by the prefrontals and the postfrontal.
The parietals are the largest elements of the skull, but they do not
greatly exceed the jugals. Together the parietals form a somewhat obtuse
oval in the median region of the skull and they contain between them, in
their posterior third, the small circular pineal foramen. The postparietal
forms the posterior boundary of the skull. The pref rental forms the
anterior border of the orbit and is triangular in shape. The lacrimal
is not identified. The maxilla is an elongate element the boundaries of
which are uncertain, though probably somewhat as given. The postfrontal
and the postorbital form the posterior boundary of the orbit, inclosing
between them the anterior projection of the squamosal. The squamosal is
an elongate element and is acuminate at each end. The tabulare is a large
element lying lateral to the postparietal. The jugal is a very elongate
element, apparently acuminate anteriorly. The quadratojugal is small and
elongate. The supratemporal is definitely bounded and its limits are as
indicated (fig. 22, B), being a large element which forms the quadrate angle.

There are two other specimens of this species in the collections and a
fragment of a fourth which it is difficult to make out. Cope identified
and figured one of these as _E. radiatus_ (Geol. Surv. Ohio, II, pt. II,
pl. 34, fig. 3), but the identification is doubtful and the figure shows
structures which I am unable to identify in the specimen. Nothing of
importance is to be learned from the other two specimens, except that they
show a diversity of size. They consist of incomplete skulls, concerning
which Cope (123) remarks:

  "There are no mucous canals. The sculpture consists of strong ridges
  radiating and inosculating. Radiation is more uninterrupted on both
  jugal, supratemporal, and anterior part of the tabulare; on the first
  they originate in front of the middle exteriorly; on the supratemporal
  near the anterior part. The inosculation is honeycomb-like on the
  parietal, postfrontal, and posterior parts of the tabulare."

Measurement of the Type Specimen.

                                                        mm.
  Length of the skull along median line (estimated)     60
  Length from muzzle to quadrate angle                  71
  Width at posterior border                             69
  Width at orbits                                       40
  Length of orbit                                        9
  Width of orbit                                         8
  Interorbital width                                     8
  Length of nostrils                                     2

Measurements of Another Specimen of the Species.

(No. 8598 G, American Museum of Natural History.)

                                       mm.
  Median length of skull               56
  Length to quadrate angle             61
  Width at posterior border            50
  Length of orbit                       7
  Width of orbit                        6
  Interorbital width                   4.5

The specimens of this species were collected by Dr. J. S. Newberry.

Erpetosaurus obtusus Cope, 1868.

  Cope, Proc. Phil. Acad. Nat. Sci., 1868, p. 213.

  Cope, Trans. Amer. Phil. Soc., XIV, p. 12, fig. 1, 1869.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 396, fig. 11, 1875.

  Cope, Proc. Amer. Phil. Soc., 1885, XXII, p. 407 (Pal. Bull. 40).

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, p. 350, pl. lx, fig. 2.

Type: Specimen No. 8601 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The species, _Tuditanus obtusus_, was first described by Professor Cope
as _Dendrerpeton obtusum_, but he subsequently referred the species
to the genus _Tuditanus_. It was removed by the writer to the genus
_Erpetosaurus_ in 1909. The species is known from two partially preserved
crania. The skull elements seem to have disappeared and left only the
impressions. The sutures are, for the most part, clearly represented, but
the skull shows no sculpturing. On the posterior third of one cranium
there is a small space which seems to be slightly sculptured, as Cope
indicated in his drawing. The general form of the skull is that of a
broad oval, truncate posteriorly. The orbits lie in the anterior third of
the skull, and the pineal foramen in the posterior third. Cope compared
the skull to that of Huxley's _Erpetocephalus_, to which it has some
resemblance. The nostrils are elongate and are situated at an obtuse angle
with relation to the main axis of the skull.

The premaxilla is small and forms the inner border of the nostril. There
seem to be impressions of small teeth, but no large ones are evident. The
nasals are separated by a zigzag suture, and are nearly square. They have
the usual relations. The frontals form a portion of the inner boundary of
the orbits and unite behind with the parietals, the anterior extensions
of which they inclose. The parietals are large elements and together
form a broad oval, truncate posteriorly. They inclose between them the
pineal foramen in the median suture. It lies in the posterior fourth of
the parietals. The postparietals are elongate transversely, and have the
usual relations. The pref rental is somewhat triangular and forms the
anterior boundary of the orbit. The lacrimal has not been detected. The
maxilla is elongate, and with the quadrate jugal forms the exterior border
of the cranium. No teeth are observed on the maxilla. The postfrontal and
the postorbital form the posterior border of the orbit, and between them
inclose the anterior extension of the squamosal. The supratemporal is
pointed anteriorly and has the usual relations of that element, joining
the postorbital, the postfrontal, the parietal, the tabulare, and the
squamosal. The tabulare is larger than the postparietal and is acuminate,
the point being inclosed by the squamosal and the supratemporal. The jugal
widens fan-shaped posteriorly. It forms a portion of the border of the
orbit. The supratemporal, as usual, forms the quadrate angle of the skull.
In front of it lies the elongate quadrate jugal.

[Illustration: Fig. 22.

  A. Outline of skull and cranial elements of _Erpetosaurus minutus_
       Moodie, from the Cannelton slates of Pennsylvania. Original
       in U. S. National Museum. × 2. _fr_, frontal; _mx_, maxilla;
       _par_, parietal; _po_, postorbital; _pp_, postparietal; =pr=,
       postfrontal; _sq_, squamosal; _spt_, supratemporal; _tab_,
       tabulare.

  B. Outline of skull and cranial elements of _Erpetosaurus radiatus_
       Cope, from the Coal Measures of Linton, Ohio; partially restored.
       × 0.75. Original in American Museum of Natural History, _fr_,
       frontal; _j_, jugal; _mx_, maxilla; _n_, nasal; _or_, orbit;
       _par_, parietal; _pf_, postfrontal; _po_, postorbital; _pr_,
       pref rental; _pp_, postparietal; _pmx_, premaxilla; _qj_,
       quadratojugal; _sq_, squamosal; _spt_, supratemporal; _tab_,
       tabulare.

  C. Palate of _Erpetosaurus_ (_tabulatus?_), from the Coal Measures
       of Linton, Ohio. × 1. American Museum of Natural History, _ex_,
       exoccipital; _m_, mandible; _mx_, maxilla; _pal_, palatine; _pt_,
       pterygoid; _prv_, prevomer; _pd_, parasphenoid; _x_, anterior and
       posterior palatine vacuities.

  D. Outline of skull and cranial elements of _Erpetosaurus
       acutirostris_ Moodie, from the Coal Measures of Linton, Ohio.
       Original in American Museum of Natural History. × 1. _ex_,
       exoccipital; _fr_, frontal; _j_, jugal; _mx_, maxilla; _n_,
       nasal; _or_, orbit; _po_, postorbital; _par_, parietal; _pp_,
       postparietal; _pf_, postfrontal; _sq_, squamosal; _spt_,
       supratemporal; _tab_, tabulare.

  E. Outline of larger part of skeleton of _Odonterpeton triangularis_
       Moodie, from the Coal Measures of Linton, Ohio. Original in U. S.
       National Museum. × 4. _h_, humerus; _il_, ilium?; _v_, vertebræ,
       all of which are not represented.

  F. Right mandible of _Erpetosaurus tabulatus_ Cope, from the Linton,
       Ohio, Coal Measures. Original in American Museum of Natural
       History. × 2. _art_, articular; _cor_, coronoid; _d_, dentary;
       _ang_, angular; _sa_, surangular.

  G. Skull elements and lateral-line canals of _Erpetosaurus
       tabulatus_ Cope, from the Coal Measures of Linton, Ohio. × 1.5.
       _fr_, frontal; _j_, jugal; _jl_, jugal lateral-line canal;
       _mx_, maxilla: _n_, nasal; _or_, orbit; _par_, parietal; _po_,
       postorbital; _pf_, lacrimal or prefrontal; _so_, suborbital
       lateral-line canal; _pp_, postparietal; _pmx_, premaxilla; _qj_,
       quadratojugal; _spo_, supraorbital lateral-line canal; _sq_,
       squamosal; _spt_, supratemporal; _tm_, temporal lateral-line
       canal; _tab_, tabulare; _so_, supraoccipital cross-commissure of
       lateral-line canal.

]

_Dendrerpeton_ is not well enough known for an exact comparison with
_Erpetosaurus obtusus_, but Cope separated the latter from _Dendrerpeton_
on the position of the orbits and the broadly rounded muzzle. This species
differs from the other species of the genus in the form of the cranium, as
well as in the characters which separate it from _Dendrerpeton_.

Measurements of the Type of Erpetosaurus obtusus Cope.

                                         mm.
  Median length of the skull             48
  Width of skull at posterior border     56
  Width across orbits                    37
  Length of orbit                        12.5
  Width of orbit                          7
  Interorbital space                     15
  Diameter of nostril                     1.5
  Diameter of pineal foramen              1.75

Two other specimens, Nos. 8602 G and 8608 G of the American Museum, are
associated in this species.


=Erpetosaurus tabulatus Cope.=

  Cope, Proc. Amer. Phil. Soc., XVI, p. 577 (Tuditanus tabulatus).

  Moodie, Jour. Geol., 17, p. 52, figs. 8, 9, 1909.

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, pp. 347, 351, pl. 59, fig.
    2; pl. 62, fig. 2, 1909.

Type: Specimen in the Zoological Collection of Columbia University.

Horizon and locality: Linton, Ohio, Coal Measures. (Plate 25, fig. 2.)

The species is known from a single well-preserved skull and its obverse in
the collection of Columbia University in New York City. I am indebted to
Dr. Bashford Dean for the privilege of studying this interesting form. It
is from the Linton deposits of Ohio. The remains include a nearly complete
cranium and a complete clavicle of the right side. The species agrees in
all essential respects with the characters of the genus _Erpetosaurus_,
presenting a broad, flat head and a triangular clavicle.

[Illustration: MOODIE                                           PLATE 13

_Dendrerpeton oweni_ Dawson. Above: Skull, mandible, and
bones of anterior limbs. Below: Posterior limb, pelvis, and bony scales.
Nearly natural size. Erect tree, South Joggins, Coal formation, Nova
Scotia. Photograph by Dawson, published through the courtesy of Dr.
Arthur Willey. Original specimen in the Peter Redpath Museum of McGill
University.]

The cranium is wider than long, the muzzle broadly rounded. The orbits are
wide ovals, and their posterior borders fall little behind the transverse
line dividing the skull equally. The interorbital width equals the long
diameter of the orbit. The posterior outline of the cranium is truncate
in a straight transverse line between the prominent tabulare angles. The
composition of the cranium is different from that of any other species
of _Erpetosaurus_ in the large size of the tabulare and the fact that
the supratemporal is excluded from the parietal by the extension of
the postorbitals and the tabulare. This may be a generic character and
entitles the species to be placed in a new genus, but it will be retained
here until more of the anatomy of the species is known. The elements of
the anterior part of the skull are not preserved, but they are indicated
by the broken lines in the drawing (fig. 22, G). The nostrils are,
however, clearly indicated as bosses of shale. There is a mere fragment
of the nasal preserved posterior to the crack indicated by the transverse
line in the drawing. The frontal is elongate as in other species of the
genus and forms the inner border of the orbit. The parietal, as usual,
is one of the larger bones of the skull roof and the pineal foramen is
inclosed in the median suture by the two parietal elements. The pineal
opening lies in the posterior half of the parietal. The postparietal is
almost square, being slightly elongate transversely, uniting laterally
with the tabulare, with which it forms the truncate table of the skull.
The suture separating the tabulare from the supratemporal is clearly
distinct. Although such a position for the supratemporal is unusual it is
not unique, since the same character has been observed in _Diceratosaurus
lævis_ Moodie, described elsewhere (p. 120) in this paper. The postfrontal
is rather small and it, together with the postorbital, forms the posterior
boundary of the orbit. The postorbital is truncate posteriorly and joins
the tabulare broadly. The supratemporal lies posterior to the postorbital
and jugal and borders the quadratojugal, which is an unusual condition,
but what significance the condition has remains to be determined.
Posterior to the supratemporal lies the squamosal, which forms the
quadrate angle of the skull. The quadratojugal is a small element and
forms part of the lateral boundary of the skull. The jugal is a large
element and forms the entire lateral border of the orbit. There are
no teeth preserved on the fragment of the maxilla, but there are some
impressions farther forward which resemble the pleurodont denticles of the
modern Amphibia.

The sculpture of the surface of the cranial bones consists of parallel
ridges which are separated by grooves equal to them in width. The ridges
radiate inward on the squamosals and f rentals and outward on the
supratemporals. They are somewhat interrupted on the other skull elements.
The right clavicle is ornamented with a sculpture of similar radiating
grooves and ridges.

Cope described an atlas in connection with this skull, but I do not find
it. The slender impressions to the right of the clavicle may possibly
represent ribs. They are gently curved and truncate at the inner end.

A nearly complete system of lateral-line canals has been detected on
this skull. The canals preserved are: the temporal, the jugal, the
infraorbital, the occipital cross-commissure, and the supraorbital. These
terms were used for the first time for the Amphibia by the writer (458)
in a discussion of the organs and their significance in the correlation
of the skull elements. The occipital cross-commissure in the present
skull is represented by a row of elongate pits, such as Andrews (8) has
described for _Ceraterpeton galvani_ Huxley from the Coal Measures of
England. The cross-commissure is contained within the tabulare. The jugal
and temporal canals form a complete ring, much as the same canals do
in _Trematosaurus_. The supratemporal in _Erpetosaurus tabulatus_ Cope
is excluded from the parietal by the extension of the tabulare and the
postorbital, and it is to be noticed that the temporal canal has a changed
position to correspond with the changed condition of the squamosal. This
is of considerable interest in connection with the correlation of the
supratemporal in fishes and amphibians. This subject has been fully
treated in another place (458) and it will only be necessary to state
here that on the basis of the lateral-line canals and their arrangement
in fishes and the Amphibia the true correlation of the supratemporal
elements in amphibians and fishes has been made. The temporal canal in the
present specimen has, apparently, an indication of a connection with the
supraorbital canal, but of this I am not sure. The jugal canal occurs on
the supratemporal and quadratojugal, and it joins the infraorbital on the
jugal. The infraorbital is indicated by a short portion a few millimeters
long under the orbit and the remainder, _i.e._, its connection with the
jugal canal, is restored (fig. 22, G). There is, nothing unusual to be
observed in that portion of the infraorbital canal which is preserved. The
supraorbital canal is indicated by a curved, broad, shallow groove on the
inner side of each orbit. As stated above, there seems to be a connection
between this canal and the temporal, but I am not sure. The primitive
conditions shown in the lateral-line canals in _Erpetosaurus tabulatus_
Cope are the presence of the occipital cross-commissure and the ring-like
formation of the temporal and jugal canals, which is too clearly indicated
to be overlooked.

Measurements of the Type of Erpetosaurus tabulatus Cope.

                                                mm.
  Median length of skull                        29
  Width of skull, posterior border, estimated   37
  Width between tabulare angles                 18
  Length of orbit                                8
  Width of orbit                                 6.5
  Diameter of nostril                            1
  Diameter of pineal foramen                     1
  Length of right clavicle                      13
  Width of right clavicle                        5.5


Mandible Provisionally Associated With Erpetosaurus tabulatus Cope.

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, pp. 351-352, pl. lix, fig.
    2; pl. lxiv, fig. 3, 1909.

This specimen is preserved almost completely on a slab of soft coal.
It is impossible to determine positively to what microsaurian species
the mandible belongs, but it may, for the present, be associated with
_Erpetosaurus tabulatus_ Cope on account of its size and the character
of its sculpture. This is the first and almost the only known example of
a mandible of an American microsaurian. The form of the jaw is perfectly
preserved, although the condition of the articular surface can not be
determined.

The proportions of the mandible, as maybe judged from the table of
measurements, are rather stout and the teeth are strong and numerous.
There are evidences of 19 teeth preserved. The sutures separating the
articular (_art_), angular (_ang_), surangular (_sa_), coronoid (_cor_),
and the dentary (_d_) (fig. 22, F) are clear for at least the greater
part of their length and they may be easily restored for the remainder of
their course. The surangular is thus seen to rival the dentary in size
and on it occurs the peculiar sculpturing which approximates so closely
that on the skull of _Erpetosaurus tabulatus_ Cope. The presence of the
long anterior tooth is strikingly characteristic of many Microsauria. It
is well developed in _Sauropleura longidentata_ Moodie and _Sauropleura
(Anisodexis) enchodus_ Cope. It is also present in well-developed form
in the later labyrinthodonts. The teeth are all, with the exception of
the fourth from the anterior end, rather short, curved, and sharply
pointed, with an indication of longitudinal fluting. The arrangement of
the mandibular elements recalls in a striking way the mandible of _Eryops
megacephalus_ Cope as figured by Branson (49).

Measurements of the Mandible Provisionally Associated With Erpetosaurus
tabulatus Cope.

(No. 8542 G, American Museum of Natural History.)

                                        mm.
  Length of mandible                    32
  Posterior width across surangular      6
  Width of dentary                       3
  Width of jaw at tip                    1.5
  Length of one of the posterior teeth   1.25
  Width across base of same tooth         .50
  Length of long anterior tooth          2
  Width of same tooth at base             .75

Another specimen of this same species is 8550 G, of the American Museum.
Linton, Ohio, Coal Measures.


PALATE OF ERPETOSAURUS TABULATUS COPE.

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, pp. 352-354, pl. lxi, fig.
    2, 1909.

The specimen is half a cranium with its impression. It is referred to
_Erpetosaurus_ on the basis of the sculpturing of the mandible and the
posterior table of the skull. On the surangular there is seen the rugosity
which is common to other members of the genus. The characters presented
are those of _Erpetosaurus tabulatus_ Cope, but the reference is rather
uncertain.

The specimen is unique among the known American material in showing the
structure of the palate. Jaekel (347) has figured and described the palate
of _Diceratosaurus punctolineatus_ Cope from the Linton beds. The present
palate differs from that species only in the enlarged ectopterygoid and
the smaller palatine.

The parasphenoid, in the present form, does not differ from that element
in other Paleozoic Amphibia. Its form is slender, arising from an enlarged
base and separating the pterygoids by its own width. The exoccipitals
are probably represented in the specimen and they have been indicated in
the drawing (fig. 22 C). They are rather large and extend some distance
under the base of the skull to unite anteriorly with the pterygoids, a
very unusual arrangement. The pterygoids are elongate elements and are
bounded anteriorly by the vomer and laterally by the ectopterygoid. The
vomer shows no evidence of being toothed, although it may have been so
anteriorly. The same may also be said for the palatines. The relations of
the ectopterygoids are rather unusual for the Amphibia, especially in the
posterior extension of the element. The bone lies all along the side of
the pterygoid and anteriorly projects forward between the pterygoid and
the palatine. In this unusual posterior projection the ectopterygoid has
almost obliterated the infratemporal foramen, which possibly may be still
represented by the triangular space between the bases of the pterygoid
and the ectopterygoid. The anterior palatine foramen (internal nares)
lies between the anterior ends of the palatine and the vomer, its usual
relations in the labyrinthodonts. The foramen may be recognized as the
rounded depression slightly anterior to the palatine.

The mandible is rather heavy and is coarsely sculptured with radiating
grooves and ridges. The character of the teeth can not be determined, save
to say that they were present. The posterior end of the mandible projects
somewhat beyond the quadrate angle of the skull.

The interest in the present specimen is heightened by the light it throws
on the characters for the separation of the Amphibia and Reptilia. The
wide separation of the pterygoids by the parasphenoid is an amphibian
character of undoubted value. The reduction of the parasphenoid in this
specimen is noteworthy.

Measurements of the Skull of Erpetosaurus tabulatus Cope.

(No. 8607 G, American Museum of Natural History.)

                                        mm.
  Length of skull in median line        45
  Estimated posterior width of skull    50
  Estimated width of parasphenoid        6
  Width of pterygoid                     5
  Length of ectopterygoid               17
  Posterior width of mandible           12


=Erpetosaurus minutus Moodie.=

  Moodie, Proc. U. S. Nat. Mus., 37, pp. 21-23, pl. 8, fig. 1, 1909.

Type: Specimen No. 4545, U. S. National Museum.

Horizon and locality: Cannelton slates, Pennsylvania (Upper Freeport).
(Plate 20 D.)

The specimen on which the species is based is composed of the greater
portion of a small skull preserved in the hard shale from Cannelton,
Pennsylvania, and was collected by Mr. R. D. Lacoe, of Pittston,
Pennsylvania. The characters of the specimen had not previously been
determined, since the museum label and number had partially obscured the
snout of the skull. The skull is very small, but has the form assumed by
other members of the genus. The specimen may belong to a young individual,
but even though it does, it is, nevertheless, quite distinct from the
other species of _Erpetosaurus_. At first sight the specimen looks like a
broken scute of some larger form. Close inspection, however, revealed the
two impressions representing the orbits, and a Zeiss binocular revealed
the characters. The large size and anterior position of the orbits,
the character of the sculpturing, the presence of the posterior table
of the skull, as in _Erpetosaurus_ (_Tuditanus_) _tabulatus_ Cope, are
the characters on which a specific diagnosis is possible. The specific
characters which distinguish this form from _E. tabulatus_ Cope, its
nearest ally, are the slight development of the posterior table, the more
delicate form of the sculpturing, the more posterior position of the
orbits, and the varying shape assumed by the parietals in the two species.
Any one of these characters would be valid as a specific character.

The pineal eye is indistinct, but is observed to lie in the broken tract
in the median line of the skull, in the middle of the portion posterior to
the orbits. The interorbital space is equal to the width of the orbit. The
orbits themselves are slightly oval and not round, as in the case of _E.
tabulatus_ Cope.

The skull elements are sculptured with radiating grooves and ridges, and
on the postparietals and tabulare the grooves take the form of pits in a
row, which undoubtedly represent the occipital cross-commissure of the
lateral-line system first observed in a microsaurian by Andrews (8) in
the skull of _Ceraterpeton galvani_ Huxley. The supraorbital canal is
represented by a slight elongate depression observable over each orbit
and extending, in one case, for about 5 mm. The presence of the circular
arrangement of the lateral-line canals in the jugal region is suggested by
a depression on the posterior edge of the squamosal.

The portion of the skull anterior to the orbits is wanting, curiously
enough, just as in _Erpetosaurus tabulatus_ Cope. In the remainder of the
skull, the post-parietals, the tabulare, the parietals, the supratemporal,
and a portion of the right frontal can be detected, although the
boundaries of but three can be accurately defined. The depression bounding
the anterior outline of the skull is taken to be the impress of the
mandible, in which case this structure would be of some depth, as in the
case of the mandible associated with _E. tabulatus_ Cope, described below.

This specimen is of interest in respect to the presence of the
lateral-line canals, its small size, and its generic identity with forms
from Ohio. There is still another form known from the Cannelton slates,
described below as _Erpetosaurus (Tuditanus) sculptilis_ Moodie.

Measurements of the Type of Erpetosaurus minutus Moodie.

                                  mm.
  Length of skull                 18
  Posterior width of skull        17
  Width of skull across orbits    14
  Length of orbit                  4.5
  Width of orbit                   3.5
  Interorbital width               3.5


=Erpetosaurus sculptilis Moodie.=

  Moodie, Jour. Geol., 17, No. 1, p. 61, figs. 11, 12, 1909 (_Tuditanus
    sculptilis_).

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, p. 347, 1909 (_Erpetosaurus
    sculptilis_).

  Moodie, Proc. U. S. Nat. Mus., 37, p. 22, 1909 (describes pectoral
    girdle).

Type: Specimen No. 12,315, University of Chicago, Walker Museum.

Horizon and locality: Cannelton slates, Pennsylvania (Upper Freeport).
(Plate 18.)

There is preserved in the collections of Walker Museum of the University
of Chicago a small amphibian skull pressed flat on a slab of slate from
Cannelton, Pennsylvania. It formed part of the Hall collection acquired by
the University of Chicago in 1908.

The specimen presents only a portion of the skull and fragmentary pectoral
plates. The skull is wider than long and the muzzle is broadly rounded.
The orbits are narrow ovals and their posterior border falls on the
transverse line dividing the skull equally. The interorbital width is
slightly greater than the width of the orbits and about equal to their
length. The posterior outline of the skull is somewhat truncate, as in _E.
tabulatus_ Cope and other species of the genus. The distal extremities of
the quadrates do not project as far backward as do the supraoccipitals.
The skull roof is formed of the regular elements, except that a quadrate
seems to be indicated by a scale of bone on the posterior angle. The
nostrils are oval and the pineal opening is small.

The premaxillæ are apparently relatively large elements, though their
boundaries are not definite. The nasal is of an oblong shape and borders
the frontal anteriorly. The frontal forms the whole of the interior border
of the orbit and borders the parietal broadly behind. The parietal is a
large element and the pineal foramen is inclosed in the median suture
about midway of the parietals. The postparietal is wider than long and
with the tabulare forms the greater part of the posterior border of the
skull. The prefrontal (plate 18, fig. 1) apparently forms the entire
anterior border of the orbit and sends an acuminate projection to the
side of it. The maxilla is excluded from the orbit and is an elongate
element with sharp conical teeth, of which there are 4 preserved. These
measure about 1 mm. in length. The jugal lies along the lateral border
of the orbit and it is acuminate both anteriorly and posteriorly. It
borders the supratemporal broadly. The postfrontal forms the greater part
of the posterior boundary of the orbit. It is triangular and acuminate
behind, and is bordered broadly by the parietal and supratemporal. The
supratemporal is also triangular and it borders the parietal broadly.
The squamosal is evidently the largest element in the skull and on
its posterior corner there is a flake of bone which may represent the
quadrate, though this is by no means certain. The quadrate has not been
detected in any of the Carboniferous Microsauria so far studied. The
tabulare is an elongate element in the transverse line of the skull. Its
entire boundary is uncertain, though part of the sutures are present. The
quadratojugal is elongate and lies posterior to the maxilla and with that
element forms the lateral boundary of the skull.

The canals of the lateral-line system have not been detected on the skull.
The sculpturing of the cranial elements consists of grooves and ridges
which radiate from a center. They are more prominent on the parietals than
elsewhere, although the other skull elements present a strong sculpturing.

There are also preserved on the slab of slate, about 10 mm. posterior to
the skull, fragments of the pectoral plates, probably representing the
clavicles and the interclavicle. They are so badly fractured that their
form can not be determined. No limbs or vertebræ have been observed.

Measurements of the Type of Erpetosaurus sculptilis Moodie.

                                    mm.
  Length of skull in median line    20
  Width of skull at posterior
    border (estimated)              24
  Diameter of orbit                  3
  Length of orbit                    4
  Interorbital space                 4
  Diameter of nostril              - 1
  Pineal foramen, diameter            .50


Pectoral Girdle Provisionally Associated With Erpetosaurus sculptilis
Moodie.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 22, 1909.

The present specimen is preserved on a block of slate from Cannelton,
Pennsylvania. It is associated with the previously described _Erpetosaurus
sculptilis_ Moodie on account of its size, the geological and geographical
distribution, and the character of the sculpture. It may pertain to an
unknown species. Other remains besides the 3 elements of the pectoral
girdle are preserved on the block of slate, but they are, for the most
part, too imperfectly preserved for recognition. Some of them are
phalanges, and I believe I detect a scapula in the rounded curved plate
lying near the right clavicle. The 3 pectoral elements, the interclavicle
and the 2 clavicles, are preserved intact, with the ventral surface
uppermost.

The specimen is particularly important in that it furnishes further
evidence of the simplicity of the microsaurian pectoral girdle, which
Jaekel regarded (347) as being extremely complex, in one species at
least, _Diceratosaurus punctolineatus_ Cope. The 3 elements are broken,
but either the elements or their impressions are present, so that
identification is possible. The elements are sculptured with radiating
grooves and ridges, as in so many of the Microsauria. The interclavicle
is spatulate and bears a general resemblance to the same element of
_Metoposaurus fraasi_ Lucas from the Triassic (383) of Arizona. The
clavicles are triangular, with rounded angles and the hypothenuse on the
interior border.

[Illustration: MOODIE                                           PLATE 14

  1 and 2. Photograph of the specimen of _Amphibamus grandiceps_
       Cope, from the Mazon Creek shales. × 1.5. Original in possession
       of Mr. L. E. Daniels, Rolling Prairie, Indiana.

  3. Specimen of _Sauropleura (Colosteus) scutellata_ Newberry, from
       the Linton Coal Measures. The species was the first known of the
       Ohio Coal Measures Amphibia; at first ascribed by Newberry to the
       fishes, but later correctly identified by Cope. × 1. Original in
       American Museum of Natural History.

  4. The type of _Diceratosaurus (Ceraterpeton) punctolineatus_ Cope,
       from the Linton Coal Measures. × 1. Original in American Museum
       of Natural History.

]

Measurements of Pectoral Girdle of Specimen No. 4539, U. S. National
Museum.

                                    mm.
  Width across the entire girdle    17
  Length of interclavicle           15
  Width of interclavicle            10
  Length of clavicle                11
  Width of clavicle, maximum         6


=Erpetosaurus acutirostris Moodie.=

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, pp. 349-351, pl. lxi, fig.
    1, 1909.

Type: Specimen No. 8598 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The present species adds another form to the diversity of structure
presented by the Carboniferous Microsauria. It is closely allied to
_Erpetosaurus_ (_Tuditanus_) _obtusus_ Cope, from the same beds (Linton,
Ohio), but differs from it especially in the position and shape of the
orbits and the acute form of the skull. Other characters which amount
almost to generic significance are found in the posterior prolongation of
the frontal and in the triangular form of the skull. Only the skull of the
animal is preserved. The character which is common to all members of the
genus _Erpetosaurus_, the cranial rugosity, is present in this species on
the squamosal and supratemporal. This character alone would not, however,
suffice to separate the form generically, but the general morphology and
arrangement of the cranial elements is such that reference to any other
genus save Erpetosaurus would not be possible.

The skull of _E. acutirostris_ takes the form of a rounded triangle. Its
base is some 50 mm. in extent, and this width gradually narrows to 31 mm.
across the orbits and still more towards the snout. The form of the skull
is not widely different from that of the type species, _E. radiatus_ Cope,
but the differences are sufficiently apparent.

Nearly all the elements of the cranium can be detected (fig. 22, D). The
bony portion of the cranium has nearly all been lost, leaving only the
impression; and the matrix in which the skull was embedded has been forced
up into the sutures between the cranial elements, thus forming ragged
ridges where the bones of the skull joined.

The position of the nostrils can not be determined accurately. The orbits
are placed well forward, a character common to several species of the
genus. The interorbital space is equal to the long diameter of the eye.
The orbits are separated by narrow prolongations of the postfrontals and
by the anterior portion of the frontals. The frontals are remarkable
in their great backward extension. In _E. obtusus_ the frontals are
nearly confined to the interorbital space. The parietals, which, on the
median suture, inclose the parietal foramen, lie well posterior, and the
parietals and the tabulare are small. A portion of the sculpturing of
these elements has been preserved and it is seen to be made up of pits
and elevations much as we find in the skull of _Saurerpeton latithorax_
Cope. The left squamosal also shows sculpturing, which here tends to
take the form of grooves and ridges, and also of pits and elevations. It
is quite probable that the anterior portion of the skull was ornamented
with grooves and ridges and undoubtedly the lateral-line canals were
well developed. The postfrontals and the postorbitals are both large
and elongated. The postorbital is especially large. The supratemporal
apparently separates the tabulare and the squamosal in their posterior
extremities. The squamosal projects posteriorly to the tabulare and
apparently even goes beyond the limits of the exoccipital. The outlines of
the jugal are fairly definite, as are also the limits of the maxilla.

Measurements of the Type of the Skull of Erpetosaurus acutirostris Moodie.

                                mm.
  Length of skull               50
  Interorbital space             9
  Width of orbit                 7
  Length of orbit               10
  Width across orbits           31
  Posterior width of skull      50
  Diameter of pineal foramen     1
  Length from tip of snout to
    posterior angle of skull    65

An additional specimen shows that the skull, of which the anterior half
is preserved, is practically of the same size as the type and shows
much the same characters, though more extensively. The sculpture of the
squamosal region is not confined to that portion of the skull, but extends
throughout the cranial elements, apparently including the premaxillæ.

The sutures, which are clearly distinct, are of the same type as has been
described for the type specimen. Perhaps one of the most interesting
characters discovered on the present specimen is that of the greater
part of the left supraorbital lateral-line canal, which is exhibited as
a rather deep and broad canal running in a slight curve across the lower
edges of the postorbital and the parietals and partly cutting the jugal.

On the left of the fossil, as it is preserved, there is an indistinct
impression of the clavicle, with the sculpture in radiating lines from
the apex as a center, such as have been found in other species of the
Tuditanidæ.

Measurements of Additional Specimen.

(No. 8607, American Museum of Natural History.)

                                           mm.
  Length of skull as preserved             40
  Anterior width across orbital region     22
  Greatest width of the skull              33
  Length of clavicle                       18
  Greatest width of clavicle                9

Still a third specimen of this species is possibly represented by a nearly
complete skull of a small individual which exposes the mandible and the
ventral portion of the skull. The remains are crushed flat, though not at
all distorted. It is quite possible that the present specimen represents
a distinct species, but only a small portion of the dorsum is present and
the shape of the cranium is indistinct, so it is retained in this species.
The portion of the skull shows the sculpture to be quite similar to that
of _Erpetosaurus acutirostris_, so far as the species is known; and the
skull apparently tapers to a point anteriorly. It may be a dwarfed or
immature form. The sculpturing of the jaw is such as we would expect of
this species.

The specimen is about half the size of the type. The palate of the skull
is well preserved and is extremely interesting. The sutures separating
the various palatal elements are not distinct. The parasphenoid is
especially large and the exoccipitals are partly ossified, if we may judge
by the projecting condyles. Anteriorly the parasphenoid contracts and
then expands and on each side of the expanded part lie fragments of the
palatines. To the right of the posterior end of the parasphenoid lies a
portion of the dorsal element showing the cranial sculpture.

The left mandible is somewhat displaced to the right of the skull, and
crushed and weathered to such an extent that the sutures are entirely
obliterated. There are 3 teeth, with indications of others. They are
typically pleurodont and sharp and slender. The mandible tapers somewhat
anteriorly and at the tip bears an elongate enlarged tooth.

Measurements of the Third Specimen of Erpetosaurus acutirostris Moodie in
the American Museum of Natural History.

                                         mm.
  Length of skull, as preserved          25
  Posterior width of skull               15
  Anterior width of skull                10
  Width across occipital condyles         4
  Length of mandible                     25
  Anterior width of mandible              2
  Length of large tooth                   1


=Erpetosaurus tuberculatus Moodie.=

  Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, pp. 348-349, pl. lviii,
    1909.

Type: Specimen Nos. 8693 G and 8610 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

This species is based on a fragmentary cranium (plate 26, fig. 1)
consisting of the posterior part of the right side of the skull. Its
association in the genus is solely on the character of the sculpturing
of the cranial elements. It is most closely related, in the characters
preserved, to the form described by Cope as _Tuditanus radiatus_, from
which it differs especially in the character of the sculpture and in
the position of the orbits, as well as the arrangement and size of the
various cranial elements, so far as these elements can be detected in the
present specimen. In _Erpetosaurus radiatus_ the skull is sculptured by
radiating grooves and ridges which did not arise from a definite center.
In _E. tuberculatus_ this center of radiation is marked by an elevation
or tubercle on each cranial element exposed, from which the grooves and
ridges radiate outward. These tubercles have an elevation of 4 mm. above
the cranial element proper. The orbit is located near the median line of
the skull, so far as can be determined. In _E. radiatus_ Cope the orbits
are located well forward. In that species also the postparietal is smaller
than in the present species and the squamosal is longer and more slender.
(Plate 25, fig. 1.)

The fragment of a skull on which the above comparison has been made
consists of the right postparietal, a portion of the tabulare, the
parietal, the frontal, and a portion of the squamosal. The other elements
are not clear. The elements in the median line are elongate, as in
_Erpetosaurus radiatus_. The pineal foramen is located well back on
the median line and lies posterior to two-thirds of the length of the
parietals. The sutures separating the frontal and parietal elements from
each other in the median line are of the zigzag form so characteristic of
the labyrinthodonts.

Measurements of the Type of Erpetosaurus tuberculatus Moodie.

                                             mm.
  Length of portion of skull preserved       52
  Width across tabulare (estimated)          60
  Length of parietal                         15
  Maximum width of parietal                  11
  Length of frontal                          22
  Width of frontal                           12


=Genus ODONTERPETON Moodie.=

  Moodie, Proc. U. S. Nat. Mus., 37, p. 19, 1909.

Type: _Odonterpeton triangularis_ Moodie.

The generic characters may be found in the triangular shape of the skull,
the large size of the teeth, the shape of the vertebræ, the small size
of the orbits, and their anterior position as shown in the type specimen
(fig. 22, E). The name of the genus is derived from the remarkable size of
the teeth as compared with the size of the skull.


=Odonterpeton triangularis Moodie.=

  Moodie, Proc. U. S. Nat. Mus., 37, p. 19, pl. 6, fig. 3, 1909.

Type: Specimen No. 4465, U. S. National Museum.

Horizon and locality: Linton, Ohio, Coal Measures.

The specimen described under the above name is a representative of the
smallest species of the Microsauria so far described from North America.
_Orthocosta microscopica_ Fritsch, from the Carboniferous of Bohemia,
is a rival of the present form in size, but the form described by
Fritsch is an entirely different animal and was formerly included among
the so-called Aistopoda, which are regarded by the writer as merely
specialized microsaurians. The present form shows clear affinities with
the Microsauria.

As may be seen by referring to the list of measurements, the skull of this
form measures only 6.5 mm. in length. The form may possibly be larval,
though I do not think so, if I may judge from the well-developed condition
of the skull bones and the complete ossification of the vertebræ. The
sides of the skull are equal and the occiput is a straight table, so that
the skull forms almost an exact equilateral triangle. The orbits are very
small and are placed well forward. The interorbital space is four times
that of the diameter of the orbit, a very unusual character and in itself
worthy of ranking as a generic character. The median suture of the skull
is zigzag and incloses the minute parietal foramen near the posterior
end of the skull. The relations of the elements of the skull, with the
exceptions of those of the frontals and parietals, can not be determined
with accuracy, although there are here and there indications of sutures.
The characters of the cranial elements, so far as they can be determined,
are those of the family Tuditanidæ, and the form may, for the present, be
regarded as a member of that group. The teeth are very long, slender, and
sharp, and are placed close together. There is no indication of fluting on
the teeth. They are slightly curved inward.

There are 13 vertebræ present. The centra are hour-glass shaped, and are
apparently phyllospondylous, with the notochord largely persistent. The
vertebral centra are unusually long and slender, with the ends rounded.
The humerus of the right side is preserved. It is a long, slender bone
with expanded extremities. There is no evidence of abdominal armature nor
of ribs (fig. 22, E).

The discovery of this form in the Linton deposits is of considerable
interest in that it indicates a wide range in size and character of the
fauna of the time. The forms now known from the Linton beds range from
Odonterpeton, which possibly had a total length of 2 inches in life, to
the form designated _Macrerpeton huxleyi_ Cope, with a skull of at least 8
inches in length and whose body may have attained a length of some feet.
The large rib described below undoubtedly indicates a large form of the
ancient Amphibia from Linton, as do also the vertebræ described by Marsh
in 1863 from Nova Scotia.

Measurements of the Type.

                                    mm.
  Length of animal, as preserved    18
  Length of skull                    6.5
  Posterior width of skull           5.5
  Length of side of skull            6.5
  Diameter of orbit                 65
  Interorbital width                 2
  Length of tooth                    0.25
  Length of vertebra                 1.45
  Width of vertebra                 35
  Length of humerus                  2.25
  Distal width of humerus           35



CHAPTER XV.

THE MICROSAURIAN FAMILY STEGOPIDÆ, FROM THE COAL MEASURES OF OHIO.


=Family STEGOPIDÆ Moodie, 1909.=

  Moodie, Jour. Geol., XVII, No. 1, 79, 1909.

The chief family characters are the large lacrimal, unknown in other
species of Coal Measures Amphibia, the central position of the orbits, the
general form of the skull, and the peculiar, short, divaricate horns from
the squamosal. If an intertemporal element is present in the skull, which
is suggested as a possibility, the family is further distinct. The type
species is Stegops divaricata Cope from the Linton, Ohio, Coal Measures.

The group seems to be distinct and has no immediate allies, being confined
to the American Coal Measures.


=Genus STEGOPS Moodie, 1909.=

  Moodie, Jour. Geol., XVII, 79, 1909.

Type: _Stegops divaricata_ Cope.

This genus has been erected for the reception of the peculiar form
described by Cope as _Ceraterpeton divaricatum_, but there are good
reasons why the form can not be retained in the genus. The position of
the orbits in Stegops (plate 25, fig. 3) is different from _Ceraterpeton_
and the muzzle is rounded, not truncate as in the latter form. The horns
are of a different type and there is no indication of the tabulare
protuberance which is present in _Ceraterpeton_. The sculpturing of the
cranial elements is also distinctive in the present form, consisting of
radiating grooves and ridges; the cranium of _Ceraterpeton_ appears to be
but slightly sculptured. There is no lateral projection from the border of
the skull in Stegops, as there is in the other genus. The structure of the
skull of _Ceraterpeton_ is practically unknown, except in a very general
way, although Andrews (8) was able to make out some of the elements and to
trace the lateral-line canals. A structural comparison is thus impossible,
but on the basis of form alone there are good generic distinctions. The
present genus is apparently distinct from other genera in the presence
of an intertemporal, but additional material will be required before
a satisfactory determination is possible. The genus _Diceratosaurus_
of Jaekel (347) is distinct in the arrangement of the elements of the
cranium, the general form of the skull, and in the two known species of
_Diceratosaurus_ the orbits are located well anteriorly, but in Stegops
they are in the median transverse line of the cranium. The genus _Stegops_
is distinct from _Eoserpeton_ in the smaller size of the prosquamosal,
in the broadly rounded muzzle, in the larger and more posteriorly placed
orbits, and in the presence of an intertemporal bone, or at least in the
elongate character of the postorbital if the intertemporal is not present.
The species on which the genus Eoserpeton is based was first described by
Cope as Ceraterpeton ten n iconic. The form is quite distinct, in spite
of Jacket's protestations to the contrary. The genus _Stegops_ stands
alone among the Carboniferous Amphibia of North America, so far as I am
aware, in the possession of a well-defined lacrimal of the labyrinthodont
type.


=Stegops divaricata Cope.=

  Cope, Proc. Am. Phil. Soc., XXII, p. 406, 1885 (_Keraterpeton
    divaricatum_).

  Moodie, Jour. Geol., XVII, No. 1, p. 79, fig. 22, 1909 (_Stegops_).

Type: Specimen No. 2559 G, American Museum of Natural History. The obverse
of this is No. 12,311, Walker Museum, University of Chicago.

Horizon and locality: Linton, Ohio, Coal Measures.

The skull on which this species is based consists of the impressions
on two slabs of coal, one belonging to the Newberry Collection of the
American Museum of Natural History, No. 2559 G, and the other to the
Gurley Collection of the University of Chicago, No. 12,311. The slab
belonging to the University of Chicago contains the better-preserved
remains, so that the description is based largely on that portion (plate
25, fig. 3). Nearly all of the elements of the skull are determined with
considerable certainty and many important characters in the morphology of
the Microsauria are thus brought out.

[Illustration: Fig. 23.--Skull elements of _Stegops divaricata_ Cope.,
_fr_, frontal; _it_, intertemporal; _j_, jugal; _la_, lacrimal;
_mx_, maxilla; _n_, nasal; _par_, parietal; _pf_, prefrontal; _po_,
postorbital; _pof_, postfrontal; _pmx_, premaxilla; _sq_, squamosal; spt,
supratemporal; _qj_, quadratojugal; _tab_, tabulare; _pp_, postparietal. ×
1.3.]

The skull is oval, elongate, truncate behind, and the quadrate angles
project into sharp horns. The orbits are elongate ovals and their center
lies in the median line which divides the skull transversely. The nostrils
are elongate and have an oblique position. The pineal foramen lies in the
posterior third of the skull.

Teeth are preserved on both maxillæ and premaxillæ. They are simply sharp
pleurodont denticles, and seem to have been fairly abundant. The bones
have been completely carbonized and nothing of the original texture
is preserved, although the details of the structure are beautifully
preserved. (Plate 25, fig. 3.)

The skull is somewhat triangular in its general form. The premaxilla lies
on the anterior border of the cranium, and forms the median border of
the nostril. The suture which separates the maxilla and the premaxilla
is not evident, and it may not be correctly defined in the figure (fig.
23). The nasal is a very large element and is elongate. It unites with
the premaxilla, the lacrimal, the prefrontal, and the parietal. It
is acuminate behind and the point is inclosed by the pref rental and
the parietal. The frontal is quite narrow and elongate, and does not
border the orbit; its posterior boundary is not accurately represented.
The radiations on the surface indicate the extent of the element. The
parietals are remarkable in being smaller than the frontal and nasal. The
pineal foramen is inclosed in the median suture in the anterior third of
the parietals. The parietal has the usual relations of that element. The
postparietal lies posterior to the parietal, but a portion of its bounding
sutures are destroyed. The prefrontal forms the antero-interior border of
the orbit and borders the postfrontal posteriorly, in an unusual manner.
The lacrimal is a large element and is clearly separable from the other
cranial elements. It, with the prefrontal, forms the anterior border of
the orbit. The maxilla is very elongate and forms the larger part of the
lateral border of the skull. Sharp-pointed teeth are present on it and
they may have been pleurodont. The lateral border of the orbit probably
received a portion of the maxilla. The postfrontal and the postorbital
form the greater part of the posterior boundary of the orbit. The
postorbital seems to be divided by a median suture which would indicate an
intertemporal bone, but this is not certain. The appearance may be due to
a fracture. The supratemporal is a large element bordering the parietal
and lies in front of the tabulare. The squamosal is elongate to form the
posterior horn-like extension of the skull. The tabulare is transversely
elongate and has the usual relations. The jugal widens to a fan-shape
backwards, and helps to form the lateral border of the orbit. Its lateral
and anterior boundaries are not assured. The quadratojugal seems to lie as
indicated, although the anterior part of the suture is not distinct. It
is apparently an elongate element and with the maxilla forms the lateral
border of the skull. The base of the skull as restored (fig. 23) is
irregular and may have had a slightly different form.

The genus _Stegops_ is exceptional in the elongate character of the
cranial elements of the single species known. In this respect it recalls
the species _Diceratosaurus lævis_ described below. The large size of the
nasals, frontals, and lacrimals and the small size of the parietals are,
so far as I am aware, unparalleled among the other Coal Measures Amphibia
of North America.

Measurements of the Type.

                                   mm.
  Median length of the skull       56
  Width across tips of horns       46
  Width at base of horns           40
  Width across orbits              44
  Diameter of the orbit             8
  Length of the orbit              15
  Interorbital space               16
  Length of the nostril             2
  Diameter of the pineal foramen    1
  Length of the teeth               1.5
  Length of the horn from base      7.5
  Width of horn at base             4

[Illustration: MOODIE                                           PLATE 15

  1. Dorsum of skull of Diceratosaurus punctolineatus (Cope), from the
       Coal Measures of Linton. Ohio. Original in the Museum at Berlin
       University. × 2. After Jaekel. _po_=postorbital: _fr_= frontal;
       _pof_=postfrontal; _j_=jugal; _la_=lacrimal; _mx_ = maxilla;
       _ps_="perisquamosal;" _pp_=post-parietal; _pmx_= premaxilla.

  2. Ventral surface of the skull of _Diceratosaurus punctolineatus_
       (Cope ), from the Coal Measures of Linton, Ohio. × 2. After
       Jaekel. _a_=anterior palatine vacuity; _ex_=exoccipital;
       _j_=jugal; _mx_=maxilla; _tr_=transverse; _pal_=palatine;
       _pt_=pterygoid; _pr_=prevomer; _ps_="perisquamosal;"
       _pv_=posterior or suborbital palatine vacuity; _ph_=parasphenoid.

  3. Pectoral girdle of _Diceratosaurus punctolineatus_ (Cope),
       from the Coal Measures of Linton, Ohio. Original in the
       paleontological Museum at Berlin. × 2. After Jaekel. _cli_=inner
       side of clavicle; _ic_=interclavicle; _cl_=clavicle (lower side);
       _cle_=cleithrum.

  4. (e) Cervical or anterior dorsal vertebra of _Diceratosaurus
       punctolineatus_ (Cope), from the Linton, Ohio, Coal Measures.
       _cv_=caudal vertebra shown with its cap of dermal bone;
       _dv_=dorsal vertebra with ribs; _x_=dermal plate on neural spine;
       _h_=humerus; _u_=ulna; _r_=radius.

]



CHAPTER XVI.

THE MICROSAURIAN FAMILY UROCORDYLIDÆ, FROM THE COAL MEASURES OF OHIO.


=Family UROCORDYLIDÆ Lydekker, 1890.=

  Lydekker, Cat. Fossil Reptilia and Amphibia, pt. IV, p. 196, 1890.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 357, 1909.

Type of the family: _Urocordylus wandesfordii_ Huxley.

Locality and horizon: Coal Measures of Kilkenny, Ireland.

  Stout and long-tailed forms, with the tabulare cornua frequently much
  produced and pitted cranial bones; lateral lines well-developed;
  palate with teeth on palatines, vomers, premaxillæ, and maxillæ, the
  two latter elements bearing conical teeth and the others bearing
  short, stumpy cones, at least in one species; pineal foramen well
  forward; nostrils and orbits in the anterior part of skull; scapula
  peculiarly curved and pointed; other pectoral elements sculptured;
  neural spines and chevrons of caudal vertebræ much dilated at their
  extremities, and pectinated; no caudal ribs; vertebræ in one genus
  apparently capped with a sculptured plate as in _Zatrachys_; tail very
  long and tapering to a point, 50 to So caudal vertebræ; dorsal region
  short; limbs well developed, with clawed digits; carpus and tarsus
  cartilaginous; endochondrium well formed.

There are 4 genera which constitute this family: _Urocordylus_, from
the Coal Measures of Ireland; _Ceraterpeton_, from the Coal Measures of
Ireland and England; _Diceratosaurus_, from the Coal Measures of Linton,
Ohio; Eoserpeton, from the Coal Measures of Linton, Ohio.

These may be distinguished by the following characters:

    I. Skull triangular, truncated behind, with rounded muzzle
         and aborted tabulare cornua, neural spines of caudal
         vertebræ long, slender, and expanded in a fan-like
         manner; tail with about 80 vertebræ; ventral scutes
         oat-like                                       _Urocordylus._

   II. Skull parabolic and of great width, with short cornua
         projecting from the supratemporal; tabulare cornua
         nearly twice as long; neural spines of caudal vertebræ
         low and wide; ventral scutes oblong; caudal vertebræ
         about 50                                      _Ceraterpeton._

  III. Skull broad with obtuse snout, tabulare cornua absent,
         large, pointed posterior expansions from supratemporal,
         posterior table within the cornua truncate; vertebræ
         with an apical sculptured plate; caudal vertebræ
         numerous, over 75; ventral scutellæ bristle-like,
         arranged _en chevron_                  _Diceratosaurus._

   IV. Skull a broad oval, with large posterior projecting
         supratemporal horns, posterior table of skull
         between cornua truncate without the small lateral
         projection from the supratemporal, orbits a long oval,
         ribs long, curved and slender, tail unknown, possibly
         shorter than in other members of the family; it is
         restored as short in Journal of Geology, XVII, p. 77,
         fig. 20, 1909, but this is uncertain; the skull has
         all the characters of the family                _Eoserpeton._

The relationships of the family are not far to seek. They fall in
immediately with the Amphibamidæ and Hylonomidæ in being among the most
reptile-like of the Paleozoic Amphibia. The group is, however, distinctly
amphibian in the possession of 4 fingers, with the usual microsaurian
phalangeal formula.


=Genus DICERATOSAURUS Jaekel, 1903.=

  Jaekel, Neues Jahrbuch f. Mineral., Geol. u. Paleon., Bd. 1, p. 112,
    1903.

  Moodie, Jour. Geol., XVII, pp. 63-69, figs. 13-15, 1909.

Type: _Diceratosaurus punctolineatus_ Jaekel.

  Orbits in the anterior two-thirds of the axial skull length, nostrils
  near to the anterior end of the skull; pineal foramen in the center
  of the skull roof; skull provided with tabulate cornua and a broad
  backwardly directed process; quadrate angle does not project on the
  border of the skull; sculpture of the cranial elements impressed as
  radial grooves; 12 presacral vertebræ, 1 sacral with expanded neural
  spine which is sculptured at the top, with simple long, apparently
  separately ossified transverse processes; extremities small; foot with
  5 digits; phalangeal formula 2-3-3-4-3.

The most important differences between _Diceratosaurus_ and
_Ceraterpeton_, the most nearly allied genus, is (in _Diceratosaurus_)
in the more anterior position and small size of the orbits, the backward
extension of the quadrate region, and the dorsal expansion of the
vertebral spines. A further, and more important, difference between the
genera is in the location of the backwardly directed processes from the
skull. In Ceraterpeton they project backward from and are a portion of the
tabulare element, while in Diceratosaurus the projection consists almost
entirely of squamosal and supratemporal.


=Diceratosaurus punctolineatus Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., 1875, p. 16.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 372, pl. xli, fig. 4, 1875.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 356, pl. lxv,
    1909.

Type: Specimen No. 8606, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The species was first described by Cope as _Ceraterpeton punctolineatum_
(122). It was redescribed on more abundant material (plate 19) by Jaekel
(347), and the following is taken from the discussions of these two
authors, checked by my own observations on the type specimen. This shows
a portion of the skull, consisting of the squamosal and supratemporal
with a projecting, convergent horn. The sculpturing on the skull is
similar to that on the pectoral plates, of which there are three preserved
(plate 14, fig. 4). The bones of the fore limbs are stout and short. The
ribs are only slightly curved. The character of the vertebræ can not be
ascertained. The sculpturing of the bones consists of radiating ridges,
grooves, and pittings.

Jaekel (347) described from the museum collection at Berlin 3 specimens of
this species, among which were 2 skulls. There were associated with these
remains some pectoral plates and limb bones with a nearly complete series
of vertebræ. A modified translation of Jaekel's description follows:

The skull of the largest specimen has, including the horns, a length of 35
mm. and a width of 30 mm. on the occipital border. From the anterior end
to the posterior border of the skull (exclusive of the horns) there is a
length of 25 mm. The pineal foramen lies about midway of this length. The
orbits are rather large, almost circular, and lie about midway between the
pineal foramen and the anterior border of the skull. The nostrils, which
lie anterior to the orbits, are a rather oblique oval and narrowed on the
lateral ends. The distance between them is about the same as that between
the orbits, which measures 7 mm.

[Illustration: MOODIE                                           PLATE 16

  1. Type specimen of _Diceratosaurus punctolineatus_ Cope, from
       Linton, Ohio, beds. × 1. Drawn from photograph. _cl_=clavicle;
       _h_=humerus; _ic_=interclavicle; _mc_=metacarpals;
       _r-u_=radius-ulna; _rb_=rib; _sc_=scapula; _sq_=squamosal;
       _vs_=ventral scutellæ.

  2. Skull of _Sauropleura longidentata_, Moodie, from the Coal
       Measures of Linton, Ohio. × 1. Drawn from photograph.
       _fr_=frontal; _m_=maxilla; _n_=nasal; _or_=orbit; _par_=parietal;
       _pp_=postparietal; _tab_=tabulare.

  3. Mandible of _Sauropleura longidentata_, Moodie, from Coal
       Measures of Linton, Ohio. × 1.5. Drawn from photograph.

  4. Type specimen of _Sauropleura enchodus_ Cope, from the Coal
       Measures of Linton, Ohio. × 1.

  5. Additional specimen of _Diceratosaurus punctolineatus_ Cope, from
       the Coal Measures of Linton Ohio. × 1. _f_=femur; _il_=ilium;
       _mc_=metacarpal; _mt_=metatarsal; _ph_=phalanx; _r_=radius;
       _t_=tibia.

]

The skull roof is sculptured with pits much like those of _Archegosaurus_.
The larger the bones, the rougher the sculpture. The bones of the middle
of the skull (that is, the parietals, frontals, premaxillæ, nasals, and
postparietals) are of the normal form and only show an unusual difference
in that they are large in the inverse order. The pineal foramen lies in
the anterior third of the parietals; that is the primitive condition
which occurs in the young forms of the Branchiosauridæ. The nostrils are
inclosed by the premaxillæ in front, in the median line by the nasals and
laterally by the maxillæ. The jugals, by their backward prolongation,
form, behind the maxillæ, the border of the skull, and only attain to some
size on the upper side of the cranium.

Jaekel's "perisquamosal" (see plate 15), which is of a doubtful nature, is
not indicated in the type specimen nor in the specimens of the other two
species (462) assigned to this genus. In _D. robustus_ and _D. lævis_ the
"perisquamosal" region is easily separable into its component elements.
The sutures between the elements may have been indistinct in his specimen,
but it is hardly conceivable that a union of the skull bones would occur
in one species and not in another of the same genus. Jaekel's suggestion
(347) that "Etwas mehr Wahrscheinlichkeit möchte ich der Vorstellung
beimessen, dass diese Ausbreitungen zum Schutz freier Kiemen dienten, wie
sie z. B. bei den Perennibranchiaten als baumförmige Organe weit am Halse
herausragen" can hardly find acceptance with students of the Paleozoic
Amphibia, since there is not the slightest evidence that the Microsauria
ever possessed external gills and considerable presumptive evidence that
they did not. His comparison of the "perisquamosal" to the "Kiemendeckel"
of the fishes is also very unhappy on morphological grounds, since the
elements of his "perisquamosal" form constituent parts of the skull roof,
which the operculum never does.

The palate of the skull (plate 15, fig. 2) has been determined by removing
the skull bones of one specimen. Anteriorly the premaxillæ and maxillæ
are clearly recognizable as large dentiferous elements. The premaxillæ
have 4 to 7 teeth, the short maxilla has 3 to 4. All the teeth are of
nearly equal size. Smaller teeth seem to be indicated by impressions found
between the larger ones. The vomers, which are tolerably large, unite with
the premaxillæ behind and inclose at least half of the palatine foramen on
the inner side. They are furnished with small teeth, which in the anterior
part are very irregularly placed, but they are more regular posteriorly.

The palatines and transverse bones are questionably identified. They
seem to lie posterior and lateral to the vomers, but the sutures are
indistinct. The large parasphenoid seems well displayed and is more or
less heart-shaped. There would seem to be a slight indication of double
occipital condyles. The pterygoids are broad plates which inclose the
parasphenoid and form the lateral boundary of the palate. The cotyli are
very indistinct, but appear as elongate grooves.

The pectoral girdle (plate 15, fig. 3) consists, apparently, of seven
elements, three paired and one unpaired. The unpaired element (the
interclavicle) is truncate posteriorly and acuminate in front, with its
surface radially grooved and the anterior borders beveled for articulation
with the clavicles. The clavicles are triangular, as is usual with the
Microsauria. They are sculptured with radiate grooves and ridges, with
decided inosculations at the ossific center. The coracoids have only
part of their surface ornamented; most of their surface is smooth for
articulation with the interclavicle and scapula. A long spine projects
from the inner surface of the coracoid. A pair of small elements lie one
on either side of the clavicles and Jaekel (347) interprets them as the
cleithra. If they are cleithra they are unique among the Microsauria.
The pectoral girdle does not, however, indicate that _Diceratosaurus_ is
"unique among all known quadrupeds."

Jaekel regards the limb which is preserved with the material as an arm
(plate 15, fig. 4), but there is no reason stated for his conclusion. It
has all of the characters of the leg and may be regarded as such. Only
a part of the lower end of the femur is preserved. The tibia and fibula
are preserved as separate rod-like elements with one of the bones longer
and larger, probably the tibia. There are 5 toes which have the customary
phalangeal formula for a microsaurian foot of 2-3-3-4(?)-3. The tarsals
are unossified.

The vertebræ (plate 15) were perforated for the notochord, and are
hour-glass-shaped, with the neural arch thickened to support a heavy
spine which bore a sculptured plate. These apical plates occur in the
dorsal region, but diminish toward the caudal vertebræ. The number of the
vertebræ in the dorsal region is very small and in the tail very large.
There are possibly 2 vertebræ in the cervical, 11 in the dorsal series;
the thirteenth carries the pelvis. There are over 100 vertebræ in the tail.

The ribs have an expanded head and the transverse processes of the
vertebræ are long.

The following account is based on the writer's study of the type specimen
and he is able to add several points of interest to a knowledge of the
anatomy of the type of this interesting microsaurian.

The type specimen consists of 11 consecutive vertebræ with a portion of
the skull, the greater portion of the pectoral girdle, parts of both
fore limbs, ribs, and ventral scutellæ (plate 14, fig. 4). The species
is represented in the collection by yet another specimen, on which Cope
based his _Tuditanus mordax_ (plate 22, fig. 5), of which he himself says:
"Further examination of the specimen on which the latter (_T. mordax_)
was founded leads to the belief that it is an imperfect cranium of
_Ceraterpeton (Diceratosaurus) punctolineatum_ Cope." The plates referred
to are rather to be regarded as elements of the pectoral girdle and I
believe they represent the clavicle and a portion of the interclavicle.

The skull of the present species is fully described by Jaekel. The
type specimen does not offer any evidence in support of Jaekel's
"perisquamosal," but rather tends to the idea that he is incorrect in his
assumption of the fusion of these elements of the skull. The direction
taken by the ridges and grooves on the elements preserved indicate a
separation between the supratemporal and the squamosal. I do not find
that the grooves have the tendency to arise from a common center of
ossification in the squamosal, as suggested in the figures of Jaekel.
The horn which projects backward from the squamosal is rather large and
heavy for the size of the skull, and after curving slightly inward ends
in a blunt point and not sharply, as Jaekel figures in his specimens. The
vertebral column is indistinctly preserved and I have nothing to add to
Jaekel's account given above.

In the structure of the pectoral girdle my results are greatly at variance
with those of Jaekel. I do not find the remarkable elements which Jaekel
has figured (347) in his specimens. On the other hand, I find a normal
microsaurian pectoral arch (464), such as has been described for numerous
other forms. There are present, distinctly preserved in the type specimen,
the scapulæ, the clavicles, and the interclavicle, with the possibility
of the coracoid. The peculiar element referred to by Cope as resembling a
"lacertilian pubis" is without doubt the left scapula of the animal (plate
16, fig. 1). Its form compares very favorably with that of _Ceraterpeton_
as figured by Woodward (630). The coracoid may be represented by the
fragment which lies close to the scapula. The sculptured element lying
next to the supratemporal horn of the skull is the right clavicle
preserved bottom side up. Of the other two sculptured elements, one is the
interclavicle, only a portion of which is preserved. The left clavicle
lies beside it. The clavicles in this species have a tendency to assume
the triangular shape so common in other species of Microsauria, and the
interclavicle, so far as can be determined, was shield-shaped. The upper
surfaces of the pectoral elements are marked by grooves for the attachment
of the pectoral muscles.

[Illustration: Fig. 24.

  A. Skull of _Diceratosaurus lævis_ Moodie, from the Linton Coal
       Measures. × 1. _f_, frontal; _j_, jugal; _mx_, maxilla; _n_,
       nasal; _or_, orbit; _par_, parietal; _pof_, postfrontal; _po_,
       postorbital; _pf_, prefrontal; _pp_, postparietal; _sq_,
       squamosal; _spt_, supratemporal; _qj_, quadratojugal; _pmx_,
       premaxilla; _tab_, tabulare.

  B. Reconstruction of skull outlines of _Diceratosaurus robustus_
       Moodie, from the Coal Measures of Ohio. × 0.75. _fr_, frontal;
       _f_, jugal; _or_, orbit; _par_, parietal; _pof_, postfrontal;
       _po_, postorbital; _pp_, postparietal; _qj_, quadratojugal;
       _spt_, supratemporal; _tab_, tabulare.

]

The ventral scutellation is present in a small patch (plate 16, fig. 1)
near the horn of the skull. The scutæ are oat-shaped and take the usual
form. The ribs are not long, are rather stout, and beyond the proximal
curve are nearly straight to the obtuse tips. The heads of the ribs are so
obscure that it is impossible to determine whether they were two-headed
or not. They are expanded proximally and there is a slight tendency to a
division of the head.

Portions of both fore limbs are preserved. The right limb possesses the
humerus, separate radius and ulna, and 2 metacarpals. The other possesses
only the radius, 3 metacarpals, and a portion of a phalanx. The humerus is
a very stout bone and at once recalls that of _Amblyrhynchus_. The ends
are expanded and there are roughnesses on the bone for the attachment of
muscles. The radius and ulna are subequal in size. They are both expanded
more proximally than distally. The carpus was cartilaginous. An additional
specimen of this species is figured on plate 16, fig. 5. This adds to our
knowledge of the pelvis especially.

Measurements of the Type.

                                         mm.
  Length of entire specimen              80
  Length of tabulate horn of skull       20
  Width at base                           4
  Width at tip                            2.5
  Length of right humerus                16
  Width at middle of shaft                3
  Width at proximal end                   5
  Width at distal end                     5.5
  Length of radius                        9
  Length of ulna                          9
  Width of radius at proximal end         2.5
  Width at middle                         1.5
  Width at distal end                     2
  Width of various portions of
    ulna same as radius.
  Length of the only phalanx preserved    5
  Length of vertebra                      5
  Width of vertebra                       4
  Length of longest rib                  17
  Width of rib at widest part             1.5
  Width of clavicle                      18
  Length of clavicle                     20
  Length of interclavicle                25
  Width of interclavicle                 16
  Length of single side of chevron scute  7
  Width of same                            .25

The specimen (No. 2566, Am. Mus. Nat. Hist.) on which Cope based his
_Tuditanus mordax_ is composed of two plates of the above-described
species.


=Diceratosaurus lævis Moodie.=

  Moodie, Jour. Geol., XVII, No. 1, p. 63, figs. 13, 14, 1909.

Type: Specimen No. 102 (8680 G), American Museum of Natural History, where
it forms part of the Newberry collection.

Horizon and locality: Linton, Ohio, Coal Measures.

The species is represented by an almost complete skull, which had been
identified previously by Cope as _Tuditanus radiatus_. The specimen
consists of the impressions of the bones of the cranial roof, the bones
themselves having disappeared. It is not probable that the dorsum of the
skull was smooth. The details in the structure of the skull have been
ascertained quite definitely. There can be no doubt that the arrangement
of the elements is accurate, as shown in figure 24 A. The supratemporal,
as in _Erpetosaurus tabulatus_ Cope, is excluded from the parietal.

The form of the skull at once recalls that of the species _D.
punctolineatus_, as figured by Jaekel (see plate 15). The orbits are
located in nearly the same region of the skull and the sutures separating
the cranial elements are quite similar in the anterior portions. The
species _D. lævis_ is based on the divergent character of the horn-like
protuberances which project from the squamosals. The horns of _D.
punctolineatus_ are convergent. The present skull is also smaller and the
parietals in _D. lævis_ are much larger than in the type species. In the
type species, also, the pineal foramen is located well forward in the
parietal, while in the present form the foramen is located well posterior.

The skull is almost rectangular. The nostrils are elongate ovals. The
orbits are circular and the distance between them is equal to two-thirds
of the dimensions of the orbit. They are located well forward in the skull
and are bounded laterally by the maxillaries. The nostrils have much the
same character as in the type form, being broadly oval.

The premaxillæ are elongate transversely, being about twice as long as
wide. They are identical in shape and relations with the same elements
in _D. punctolineatus_ Cope. The nasal is nearly square and forms
the interior boundary of the nostril. The frontal is elongate in the
median length of the skull and it is acuminate posteriorly, where the
acumination is inclosed by the parietal and postfrontal. The parietals are
by far the largest elements in the cranium. They form together an oval
which is elongate in the longitudinal diameter of the skull. They inclose
between them, in the median suture, the small pineal foramen. They are
acuminate in front, with a broad truncate posterior base, where they are
bounded by the postparietals. The postparietal is nearly square, being
somewhat wider than long. It joins the tabulare and the parietal. The
tabulare is elongate in the long diameter of the skull. It ends anteriorly
in a point which is inserted between the postorbital and the parietal, and
bears a short protuberance posteriorly, much as does the same element in
the type species.

There are four elements which take part in the formation of the posterior
border of the skull. These are the postparietal, the tabulare, the
squamosal, and the supratemporal. It is very unusual for the supratemporal
to reach the posterior edge of the cranium. The pref rental lies anterior
to the orbit, of which it forms the anterior border. The lacrimal has not
been detected, although Jaekel (347) has indicated it in his drawings
of the skull of the type species. The maxilla is elongate and forms the
lateral border of the skull. No teeth have been detected, although they
were doubtless the same as Jaekel has figured in _D. punctolineatus_.
The jugal is an elongate element joining the maxilla posteriorly. Jaekel
included this element in his "perisquamosal," but the sutures are clearly
evident in the present specimen and there is no evidence of a structure at
all similar to a "perisquamosal." The postorbital is fully as large as the
jugal which it joins, forming a part of the posterior border of the orbit
and ending posteriorly in a point which is inclosed by the tabulare and
the squamosal. The postfrontal with the foregoing element forms the entire
posterior border of the orbit and it likewise ends in a point inclosed
by the parietal and the postorbital. The quadratojugal has much the same
shape and relations as in _D. punctolineatus_, although it is located
further back. The squamosal is also elongate, as are most of the posterior
cranial elements, and it also has an acumination which is directed forward
and is inclosed by the postorbital and jugal. The anterior suture of this
element is rather indistinct, but it is, I believe, as represented (fig.
24). The element is elongate and is prolonged posteriorly to form the
horn, which ends in a blunt point and is not sharp, as in the type species.

Jaekel (347) regards the species _Diceratosaurus punctolineatus_ Cope
as being unparalleled among known vertebrates in the possession of a
"perisquamosal" element. In closely allied species the "perisquamosal" is
easily separated into its component elements, and the morphology of the
present skull would throw considerable doubt on Jaekel's interpretation
of the skull of the type species. Another specimen, described below as
another species of this genus, shows no evidence of this fusion. So far as
I can learn, there have been no cases of true fusion of cranial elements
correctly reported, unless it be that which possibly exists between the
two frontals in the skull of _Diplocaulus_. It was on the basis of such
fusions that Maggi (397) proposed to derive the interparietals of the
primates from the tabulare of the stegocephalians.

The posterior outline of the skull in the present specimen is not well
preserved and the outline as given may be slightly inaccurate. The
indentation figured by Jaekel in the posterior border of the skull of the
type form is not present in the species under discussion.

Measurements of the Type Skull of Diceratosaurus lævis Moodie.

                                              mm.
  Length of skull along median suture         37
  Length from muzzle to tip of horn           50
  Width between tips of horns, estimated      40
  Width of orbit                               7
  Length of orbit                             10
  Width of skull across the orbits            30
  Interorbital width                           6
  Length of nostril opening                    2
  Width of nostril                             1
  Diameter of the pineal foramen             - 1


=Diceratosaurus robustus Moodie.=

  Moodie, Jour. Geol., XVII, No. 1, p. 67, fig. 15, 1909.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 355, pl. lxiii,
    fig. 2, 1909.

Type: Specimen No. 8611 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The present species is indicated by the left portion of a cranium
representing a large individual. The characters of the skull are so
clearly marked that it seems worthy of description. The presence of horns
as given in the restoration of the skull (fig. 24, B) is based on the
analogy with the other two species of this genus, in both of which horns
are present. The generic determination of the species is based on the
large size of the postorbital, which is essentially characteristic of the
other species of _Diceratosaurus_.

The characters which distinguish the species from others of the genus are
the large postorbitals and the small parietals, which are excluded from
union with the postfrontals on account of the large size of the frontal.
In the other two known species the frontal is small and the parietal comes
forward to join the postfrontal. The present species exhibits a skull
which is nearly twice as large as that of _D. lævis_ and nearly three
times the size of the skull of _D. punctolineatus_.

The portion of the skull preserved shows the cranium to have had a rather
acuminate snout, not blunt as in the type species. The orbit is an
elongate oval, although it has the same relative position in the skull
as in the other species. The nostril is indicated by an oval depression
near the anterior edge of the skull. The frontals, as indicated by the
sutures present on the portion of the skull which is preserved, are fully
as long as the parietals. Whether they were as wide as is represented is
uncertain. The postfrontals are very small bones, the sutures of which are
somewhat uncertain, although they can not be far from what is represented
(fig. 24, B). The postorbital is large and elongate, and is distinctive of
this species on account of its unusual size, although it does not attain
the same proportions as in other members of the genus. The parietals are
elongate and narrow. The pineal foramen is represented by its lateral
edge and its position is about midway of the longitudinal diameter of
the parietals. The narrow postparietal is represented by its anterior
border; as restored (fig. 24, B) it may be too long. The tabulare, also,
is represented by an anterior portion and it shows this element to have
the position and form which is typical of the form _Diceratosaurus lævis_.
Such other of the cranial elements as are indicated are based on the
relations discovered in _D. lævis_.

The heavy line on the left of the drawing (fig. 24, B) represents the
outline of the preserved portion. The skull, as restored, may be a little
too long, and the shape of the horns is conjectural. In the orbit there
are preserved 2 misplaced teeth showing longitudinal fluting. The longest
tooth is about 3 mm.

Measurements of the Type Skull of Diceratosaurus robustus Moodie.

                                       mm.
  Median length of skull, estimated    67
  Posterior width of skull, estimated  78
  Length of orbit                      18
  Width of orbit                       12
  Length of longest tooth               3
  Width of same tooth at base           1.5
  Length of postorbital                27
  Width of postorbital                 14


=Genus EOSERPETON Moodie, 1909.=

  Moodie, Jour. Geol., XVII, pp. 76-79, fig. 20, 1909.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, p. 355, pl. lxiii, fig. 1,
    1909.

Type: _Eoserpeton tenuicorne_ Cope.

The genus was proposed for the reception of a single species originally
referred by Cope to _Ceraterpeton_ (_C. tenuicorne_). The species can
not be placed in the genus Ceraterpeton on account of the form and
structure of the skull, which varies widely from that of the type species,
Ceraterpeton galvani Huxley, from the Kilkenny Coal Measures of Ireland.
The most important character in which the present species differs from _C.
galvani_ is the peculiar form taken by the squamosal and by the position
of the "horn." These characters will be evident on referring to figure
25. No undoubted remains of _Ceraterpeton_ have been found outside the
British Isles. Fritsch referred (251) a species, previously described as
_Scincosaurus crassus_, to this genus, but Andrews (8), Jaekel (347) and
Woodward (630) all unite in placing the species in the genus where it was
formerly described. Jaekel even says that the Scincosaurus has no horns,
so far as he can determine. Cope referred 3 species (123) from the Linton
Coal Measures of Ohio to the genus _Ceraterpeton_, but it has been shown
elsewhere (347) that no one of them belongs in the genus, nor in fact do
they all belong in one genus.


=Eoserpeton tenuicorne Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, pp. 372-373, pl. xlii, fig. 2,
    1875.

  Cope, Proc. Am. Phil. Soc., XXII, p. 407, 1885.

  Cope, Proc. Am. Phil. Soc., XXXVI, p. 85, pl. iii, fig. 2, 1897.

  Moodie, Proc. U. S. Nat. Mus., vol. 37, p. 23, 1909.

Type: Specimen in the American Museum of Natural History. There are also
specimens Nos. 4472 and 4473 in the U. S. National Museum.

Locality and horizon: Linton, Ohio, Coal Measures.

The species was founded on a complete skull preserved on obverse sides
of a block of coal. Cope (123, pl. XLII, fig. 2) figured this skull. The
figure is poorly executed and does not do justice to the specimen, which
is really well preserved. In general the skull is oval, with the orbits
located well towards the acuminate snout. The interorbital space is equal
to twice the width of the orbit. The pineal foramen lies near the center
of the skull. The quadrate angles are drawn out into slender acuminate,
longitudinally striate horns, processes from the squamosal. The "horn"
arises from an expanded base, which is a portion of the cranial element
at the postero-lateral angle of the skull. This character is taken as
the distinctive one of the genus. It is possessed by no other form of
Carboniferous air-breathing vertebrate, in association with the other
characters of the form.

Measurements of the Type of Eoserpeton tenuicorne.

                                         mm.
  Median length of skull                 26
  Width across squamosal enlargement     30
  Width across base of horns             25
  Length from muzzle to tip of horn      40
  Length of horn                         10
  Width of horn at base                   4
  Length of orbit                         4
  Width of orbit                          3
  Interorbital span                       6

Nos. 4472 and 4473, U. S. National Museum, from Linton, Ohio, Coal
Measures.

                                         mm.
  Median length of skull                 16
  Maximum width of skull                 20
  Length of horn from base                7
  Length of orbit                         3
  Interorbital width                      3.5
  Length of vertebral column to sacrum   33
  Length of femur                         5.5
  Length of tibia and fibula              3
  Length of second digit (incomplete)     7
  Length of metatarsal                    1.5
  Length of clavicle                      6
  Width of clavicle                       3.5

[Illustration: Fig. 25. Restoration of skeleton of _Eoserpeton tenuicorne_
Cope. × 1 .5.

  Skull: _pmx_, premaxilla; _n_, nasal; _fr_, frontal; _par_, parietal;
       _pf_, prefrontal; _mx_, maxilla; _pof_, postfrontal; _po_,
       postorbital; pp, postparietal; _j_, jugal; _qj_, quadratojugal;
       _spt_, supratemporal; _sq_, squamosal; _tab_, tabulare.

  Skeleton: _ic_, interclavicle; _cl_, clavicle; _sc_, scapula; _h_,
       humerus; _r_, radius; _u_, ulna; _c_, carpus; _sr_, sacral rib
       (uncertain?); _il_, ilium; _f_, femur; _fb_, fibula; _t_, tibia;
       _ts_, tarsus.

]

The boundaries of the premaxillæ are indefinite, but what remains of
the sutures indicates that the elements were small. No teeth have been
detected. The nasal is likewise not clearly defined, but the frontal
is an elongate element which occupies the space between the orbits and
joins the parietal posteriorly. The parietals form a large oval space, so
characteristic of many of the Carboniferous Microsauria, in the anterior
third of which occurs the median parietal foramen. The postparietal is
almost square, and forms part of the posterior boundary of the skull.
The tabulare has the usual position and relations. The prefrontal is
ill defined. The postfrontal is small and forms a slender rod on the
postero-inner boundary of the orbit. The postorbital is small and its
bounding suture with the postfrontal is indefinite. The jugal is only
partially represented in the specimen, and that part forms the outer
boundary of the orbit. The maxillary sutures are not defined. There are
no evidences of teeth, since the skull is compressed dorso-ventrally. The
quadratojugal is, apparently, a larger element than usual, with the visual
relations. The supratemporal lies in great part in front of the squamosal,
but still has the normal relations of that element. The squamosal is the
characteristic feature of the skull. It is very tumid at its base and
projects into a long, slender, acuminate horn, the tumid portion being
ornamented by radiating striæ.

Another specimen of this species presents the greater part of the
skeleton. However, very little can be added to our knowledge of the skull
structure. It is barely possible that the second specimen may be distinct
from the type. The horns are curved inward, but otherwise there is little
or no difference. One of the most interesting and important features
of the complete specimen is the unusual preservation of a leg, with
impressions of 15 or more vertebra;, and traces of curved ribs which are
intercentral in position.

The femur is slender and expanded at the ends, with the articular surfaces
well formed. The tibia and fibula are mere rods of bone, although the
tibia has slightly expanded extremities. There is no osseous tarsus.
There are 5 digits in the foot; the second one is entire and contains 4
phalanges; the other digits are incomplete. The foot is remarkably long
and slender, and is fully as long as the tarsal space plus the tibia, with
the terminal phalanx clawed.

There are impressions of 2 oval and elongate clavicles in the pectoral
region. The outer end is not expanded as is usual, and the surface is
ornamented with grooves and ridges which radiate from a common center.

The entire remains measure scarcely 3 inches in length and it is to be
doubted if the creature attained a length of more than 4 inches. It is
probably a young form, but there are no evidences of external gills. The
chevron armature is but poorly preserved, but so far as can be determined
it is not different from that of other Microsauria, such as _Amphibamus_.

[Illustration: MOODIE                                           PLATE 17

Type of _Saurerpeton latithorax_ Cope. × 1.5. Original in U. S. National
Museum.]



CHAPTER XVII.

THE MICROSAURIAN FAMILY AMPHIBAMIDÆ, FROM THE COAL MEASURES OF MAZON
CREEK, ILLINOIS.


=Family AMPHIBAMIDÆ new family.=

  Small, lizard-like, terrestrial or semi-aquatic, megacephalic
  microsaurians, known from 3 species. The family characters are the
  huge size of the head as compared to the body, the short, stumpy body
  with about 25 short dorsal vertebræ, a very short tail, phalanges
  clawed, pubis of calcified cartilage, sclerotic plates in the orbit to
  the number of 29 or 30 in each, ventral armature well developed. Teeth
  anisodont, sharp, conical, non-striate.

Two genera are associated in this family: _Amphibamus grandiceps_ Cope,
known from three nearly complete skeletons; _A. thoracatus_ Moodie, known
from a single incomplete skeleton; _Cephalerpeton ventriarmatum_ Moodie,
anterior portion of body and skull. The species are all from the Mazon
Creek shales and the family seems unrepresented elsewhere. It may be
necessary to compare the Amphibamidæ with the Hylonomidæ when the latter
group is better known, but in the light of our present knowledge the two
families are distinct.

The genera may be distinguished as follows:

  I. Size small, less than 3 inches in total length, skull with deeply
       incised tympanic notches (ear-slits) _Amphibamus_

  II. Size relatively large, body-length 6 inches or more, teeth
       distinctly anisodont, skull with nearly even posterior table,
       limbs very long, ventral armature highly developed _Cephalerpeton_


=Genus AMPHIBAMUS Cope, 1865.=

  Cope, Proc. Phila. Acad. Nat. Sci., 1865, pp. 134-137. Geol. Surv.
    Ills., 11, pp. 135-141, pl. xxxii, 1 text-fig.

  Hay, Proc. Am. Phil. Soc., XXXIX, p. 120, 1900.

  Moodie, Jour. Geol., XVII, p. 81, fig. 24, 1909.

Type: _Amphibamus grandiceps_ Cope.

The publication of the type species of this genus began the researches
of Professor Cope on the extinct Amphibia of North America, which he
continued for so many years with such excellent results (105-177). The
description was based on a single specimen (plate 3, fig. 7) belonging
to Mr. Joseph Evans, of Morris, Illinois, who loaned it to Dr. Worthen
for the Illinois Geological State Survey (107), in order that it might
be described. The type has been destroyed by fire; so I am informed by
Mr. L. E. Daniels, of Rolling Prairie, Indiana. There are two other known
specimens of the species. One is in the collection of Mr. Daniels and the
other No. 794, of Yale University Museum.

This genus may be clearly separated from all the other microsaurians by
characters which are peculiar to the form. Among these may be mentioned
the possession of sclerotic plates in the eyes; the large size of the
orbits in comparison with the dimensions of the skull; the short, broad
form of the body; the very short tail; the possession of a calcified
cartilaginous pubis; clawed phalanges; presacrals 22. The character which
places the genus distinctly in the Microsauria is the possession of long,
slender, curved ribs, first detected on Mr. Daniels's specimen (plate 14,
figs. 1, 2), by Dr. Hay (316). Its stegocephalian characters are evident
in every particular of its anatomy the roofed skull, the arrangement of
the cranial elements, the presence of a well-developed ventral armature,
and the digital formula (4 for the hand and 5 for the foot).

The genus _Amphibamus_ was regarded by Cope as a representative of a new
order of vertebrates which he called (105) Xenorachia. He later (123)
abandoned this, however. Fritsch (251), Zittel (642), and others regarded
_Amphibamus_ as a branchiosaurian. The exact position of the form was
uncertain until 1900, when Dr. Hay (316) described the long, curved ribs
and suggested its place among the Microsauria. He, however (Cat. Foss.
Vert., p. 410), made the mistake of including the branchiosaurian family
Protritonidæ, under Microsauria, thus confusing the subject further. The
genus (462) has not the slightest relationship with the Branchiosauria.


=Amphibamus grandiceps Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., pp. 134-137, 1865; Geol. Surv.
    Ills., 11, pp. 135-141, pl. xxxii, and 1 woodcut, 1866.

  Hay, Proc. Am. Phil. Soc., XXXIX, p. 120, 1900.

  Moodie, Jour. Geol., XVII, No. 1, p. 82, fig. 24, 1909.

  Moodie, Kan. Univ. Sci. Bull., VI, No. 2, pp. 343-349, pl. 1, figs. 1
    and 2; pl. 5, fig. 3; pl. 7, fig. 1; pl. 11, 12, 13, 1912.

Type: Specimen has been destroyed. There is an excellent specimen (plate
4, figs. 5. 6), No. 794 (1234), in Yale University Museum, and another
nearly as good in the possession of Mr. L. E. Daniels, of Rolling Prairie,
Indiana.

Horizon and locality: Mazon Creek shales, near Morris, Illinois.

The form of the skull of _Amphibamus grandiceps_ Cope is not unlike that
of _Tuditanus minimus_ Moodie (462) from the Linton, Ohio, beds, but
it is less acuminate than in that form. The large size of the orbits
is especially striking. The shape of the skull is triangular, with
concavities in the posterior table which correspond to the ear-slits so
characteristic of _Metoposaurus_ (242) from the Keuper of Germany. The
narrowed posterior table of the skull is truncate, as in several other
genera of Microsauria, notably _Tuditanus_ and _Saurerpeton_. In structure
the skull differs but little from many of the other Carboniferous forms,
but the arrangement of the elements of the skull is more regular than in
other genera.

The premaxillaries are very small elements in the anterior tip of the
skull. They border the nares. The skull is rather peculiar among the
Microsauria in the possession of a distinct lacrimal. I have detected
this element in the cranium of _Stegops divaricata_ Cope. As here defined
the lacrimal is triangular, with its posterior border formed exclusively
by the prefrontal. Its other relations are the normal ones. The nasal
is elongate, with the usual relations of that element. The frontal
is slightly longer and broader than the nasal. It apparently forms a
portion of the inner border of the orbit. The parietal foramen lies in
the anterior fourth of the parietal, a rather unusual position for this
structure. The parietals, as in so many of the Microsauria, together
form the largest element of the skull and are roughly a triangular area
in the postero-median portion of the skull. The postparietal and the
tabulare are clearly distinguishable and they have the usual relations
for those elements. The maxillary, jugal, and quadratojugal together form
the greater part of the maxillary border. The postero-lateral angle of
the skull is, as visual, formed by the squamosal. The orbit is bounded
posteriorly by the postorbital and the postfrontal, which include in the
angle between them the quadrangular squamosal. The orbit is especially
remarkable for its size as compared with the dimensions of the skull,
being without a parallel among other known Microsauria. Around the border
of the orbit in the specimen Cope studied (105) there were found 14
quadrangular plates which he called "superciliary plates." Hay (316) was
inclined to regard them as sclerotic plates. In the Yale Museum specimen
(plate 4, figs. 5, 6) there are 20 of these plates, and there seems to be
no doubt that they are sclerotic elements. In the restoration (fig. 26) 29
sclerotic plates are given, but there is no assurance that this number is
the exact one. They may also have been slightly larger, but not as large
as in Branchiosaurus.

[Illustration: Fig. 26. Restoration of body outline and skeleton of
_Amphibamus grandiceps_ Cope, from Mazon Creek, Illinois, shales.
Restoration is based on complete specimens of the species and on Cope's
drawing. Form of body is indicated in one specimen, that in possession of
Mr. Daniels. × 1.5.

  Skull: _pmx_, premaxilla; _n_, nasal; _fr_, frontal; _par_, parietal;
       _la_, lacrimal; _pf_, prefrontal; _pof_, postfrontal; _po_,
       postorbital; _pp_, postparietal; _spt_, supratemporal; _mx_,
       maxilla; _j_, jugal; _qj_, quadratojugal; _sq_, squamosal; _tab_,
       tabulare.

  Skeleton: _ic_, interclavicle; _cl_, clavicle; _sc_, scapula; _h_,
       humerus; _r-u_, radius, ulna; _r_, carpus; _pu_, pubis; _il_,
       ilium; _f_, femur; _t_, tibia; _fb_, fibula; _ts_, tarsus; _x_,
       ischium.

]

The vertebral column is preserved nearly entire in the Daniels specimen
and quite entire (478) in the Yale specimen. Cope, in his study of the
type (105, 107), thought there could be no more than 13 presacrals, but
the specimen was poorly preserved and indecisive on this point. Dr. Hay
(316) was inclined to the opinion that there were less than 20. The Yale
specimen shows 22 centra, which are elongate, hour-glass-shaped bodies,
with the neural spine a long, low crest running the entire length of the
centrum, with a median elevation, so that in lateral view the spine would
be triangular in form. The body of the centrum is expanded laterally into
a diapophysis which extends anteriorly. The posterior vertebræ, at least,
had the notochord largely persistent. The osseous part of the vertebra
seems to have been but a thin shell, and the structure of the zygapophyses
can not be determined. That they were dorsal in position is, however,
evident from several vertebræ. The points of these structures project
laterally. The tail is short and the caudal vertebræ weakly developed.

There are distinct impressions of at least 12 pairs of ribs in the Daniels
specimen. They are long, slender, and curved, and there is no definite
assurance that there were as many ribs as are indicated (fig. 26) in the
restoration (462). The ribs are intercentral (469) and probably occupied
the full length of the vertebral column. There may have been as many as
indicated in the restoration.

One of the most interesting features of the Yale specimen is the
preservation of a small patch of skin, evidently from the back, lying to
one side near the head, measuring 5 mm. in length by 3 mm. in width. The
fragment shows the skin to be of tuberculated scales, 4 of which occupy
the length of 1 mm. The scales are somewhat hexagonal, almost rounded, and
were relatively quite thick. They lie in a close mosaic (fig. 27).

[Illustration: Fig. 27. Skeleton of _Amphibamus grandiceps_ Cope. × 1.4.

_c_, carpus; _cl_, clavicle; _cr_, caudal rib; _cv_, caudal vertebra; _f_,
femur; _h_, humerus: _il_, ilium; _s_, skin: _or_, orbit: _r_, radius;
_ul_, ulna; _sc_, scapula; _sp_, sclerotic plates; _t_, tibia and fibula;
_ts_, tarsus; _vs_, ventral scutellæ. Specimen No. 794, Yale University
Museum.]

The Yale specimen has, very well preserved, a portion of the ventral
scutellæ, of the throat, chest, and belly. The arrangement of the plates
on the throat and chest is almost exactly the reverse of what Credner has
described (190) for _Branchiosaurus amblystomus_ Cred. On the throat, in
the present form, the chevron points anteriorly, and it is the anterior
prolongation of the belly scutes with the postero-lateral projection of
the gular scutes which form the chest and arm scutellation. The belly
chevrons point anteriorly, as in _Branchiosaurus_, the rods formed by the
scutes being straight and not curved as in _Branchiosaurus_. The entire
ventral armature preserved is displaced to the left of the animal and only
the anterior portion is preserved.

The pectoral girdle is only partially known. The scapula is
crescent-shaped. The other elements are indicated only by fragments and
nothing is known of their form.

The arm elements are nearly all known. The humerus is slender and expanded
at the ends, with its articular surfaces well developed. The separate
radius and ulna are of approximately the same size and length. The
carpus is unossified. The complete phalangeal formula for the hand of
_Amphibamus_ is unknown. The third digit seems to have 4 elements. The
formula 2-2-3-2 has been suggested (462).

The pelvis is very satisfactorily known. The ilium is a long, slender,
straight rod, with expanded ends. The ischium is shown on both sides of
the vertebral column in the Yale specimen. Its form is almost identical
with that of _Paleohatteria longicaudata_ Credner, from the Rothliegenden
of Saxony. The ischia are apparently approximate in the median line,
though this character is somewhat obscured by the impression of the
caudal vertebræ. Their relation with the ilium, other than that they
were posterior to it, is uncertain. The pubis is, apparently, calcified
cartilage. It is a squarish plate, somewhat corrugated, lying anterior
to the ilium in the Daniels specimen. The elements of the pelvis were
undoubtedly hung loosely in the flesh, as in modern salamanders, since
there is no indication of articular surfaces.

The hind limb is well known, the type having a nearly complete leg with
the foot. The Daniels and the Yale specimens supplement and substantiate
the type. The femur is longer than the humerus, but more slender, with its
articular surfaces about as well developed as in the humerus. The element
is a simple rod of bone without muscular crests of any kind. The tibia
and fibula are, likewise, slender separate rods of bone. The tarsus is
unossified. The phalangeal formula is 2-2-3-4-3, and is fairly definite.

[Illustration: Fig. 28. Restoration of probable appearance of _Amphibamus
grandiceps_ Cope on the basis of the material described herewith. × 1.5.]

In the type specimen the matrix in the orbit was blackened as if by the
_pigmentum nigrum_ of the choroid. The same has been noticed in other
specimens. Professor Cope thought this indicated that the animal was
nocturnal.

There are many characters in _Amphibamus_ which seem to approximate the
reptilian type of structure. Among these may be mentioned the character of
the articular surfaces of the limb bones, the intercentral position of the
ribs, the incipient double-headedness and the curvature of the ribs, the
presence of a cartilaginous calcified pubis, the length of the limbs, and
the clawed character of the phalanges.

_Amphibamus_ was a low, flat, short, and undoubtedly a creeping, crawling
animal, possibly spending a portion of its time in the water; but it
could not have been a swimmer. It was one of nature's first attempts at
constructing a land vertebrate.

Measurements of Amphibamus grandiceps Cope.

Collection of Mr. L. E. Daniels, of Rolling Prairie, Indiana:

                                               mm.
  Entire length of specimen                    62
  Posterior width of head                      15
  Length of head                               15
  Posterior height of skull                     3
  Length of orbit                               5
  Width of orbit                                3.5
  Interorbital width                            4
  Width of skull in front of orbits            11
  Width of skull just back of orbits           16
  Length of presacral region of the
    vertebral column                           30
  Length of tail                               13
  Length of fore limb                          13.5
  Length of humerus                             4
  Length of radius and ulna                     3
  Length of right hand as preserved             3.5
  Length of rib along curve                     5.5
  Length of hind limb                          17
  Length of ilium                               4
  Length of vertebral centrum                   1.75
  Length of portion of scapula (?) preserved    4.5
  Length of foot                                6.5
  Width of impression of body midway           16

No. 794 (1234), Yale University Museum:

                                               mm.
  Length of skeleton                           67
  Length of skull                              15
  Posterior width of skull                     15
  Depth of tympanic notch                       4
  Width of tympanic notch                       6
  Long diameter of the orbit                    7
  Transverse diameter of the orbit              5.5
  Interorbital width                            4.5
  Diameter of pineal foramen                     .75
  Length of cervical series of vertebræ         9
  Length of dorsal series                      35
  Length of caudal series                      13
  Length of a centrum of the dorsal series      1.5
  Length of dorsal rib                          3.5
  Length of arm                                20
  Length of humerus                             7
  Length of radius and ulna                     4
  Width of carpal space                         3
  Length of third digit                         5
  Length of leg                                25
  Length of ilium                               3
  Length of femur                               9
  Length of tibia and fibula                    5
  Length of carpal space                        4
  Length of 1st digit                           3
  Length of 2d digit                            4.5
  Length of 4th digit                           7
    3 ventral scutellæ in 1 mm.


=Amphibamus thoracatus Moodie.=

  Moodie, Proc. U. S. Nat. Mus., 40, pp. 431-433, fig. 2, 1911.

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 347-349, pl. 5, fig. 2,
    1912.

Type: Specimen No. 4306, U. S. National Museum.

Horizon and locality: Mazon Creek shales, near Morris, Illinois.

The type is a part of the collection of Mr. R. D. Lacoe, in the U. S.
National Museum. The fossil is very poorly preserved, but the remains are
to be seen on both halves of the nodule, so that considerable can be made
out as to its structure.

The chief diagnostic characters which will at once distinguish the species
are the elongate arm, large interclavicle, shape of the vertebra, and
triangular skull.

The portions of the animal which are preserved are the impression of
the skull with one orbit, the right humerus and radius with portions of
others, and traces of ventral scutellæ. These remains are so intermingled
with the remains of plants that it has been quite difficult to distinguish
bone impression from plants. This, however, has been done by whitening the
fossils with ammonium chloride, when the texture of the fossils serves
to distinguish the one from the other. Parts of the plants have been
converted into galena and kaolin, as have also parts of the bones, so the
task has been rendered doubly difficult. There can be no doubt, however,
that the observations recorded below are correct. The position of the
arm in relation to the pectoral girdle and the position of the girdle in
relation to the skull impression first called attention to the possible
presence of a fossil amphibian.

There is little to be said of the skull. It is merely an impression in the
nodule. It is triangular in form, with the snout an acute angle. The angle
is, however, exaggerated by the compression to which the fossil has been
subjected. The right side of the skull lies over a portion of some plant.
The animal is preserved on its back, so that this gives a good opportunity
for the study of the pectoral girdle, which is partially preserved.
The interclavicle is very large and from it the species has been given
its specific name (_thoracatus_--armed with a breast plate). It is an
exaggerated =T=, with the stem very short with its anterior margin
curved, and ending in a rather sharp, elongate point. The interclavicle
recalls, in a measure, the same element of the Branchiosauria, although
it is much more expanded anteriorly and has a shorter spine. In these
respects it resembles more nearly a reptilian interclavicle (fig. 14 B).

The clavicle is of the simple triangular shape so characteristic of the
Microsauria. It is somewhat displaced backward and its inner margin is
slightly obscured. The humerus is elongate, apparently cylindrical, and
with expanded ends, resembling very closely the humerus of _Amphibamus
grandiceps_, although its proportions are much greater than in that
species. Its length is almost equal to the length of the skull, while in
_A. grandiceps_ the length of the humerus is only half that of the skull.
The radius (ulna?) resembles in its general proportions those of the
humerus. It is a more elongate, slender, lighter bone. The impression of
the other bone of the forearm is obscured.

A portion of a single vertebral centrum from the posterior part of the
dorsal series is preserved. It is apparently amphicœlous; its width is
nearly half greater than its length.

Measurements of the Type of Amphibamus thoracatus Moodie.

(No. 4306, U. S. National Museum.)

                                             mm.
  Length of entire specimen, as preserved    60
  Length of skull impression                 18
  Greatest width of same                     15.5
  Long diameter of right orbit                4
  Transverse diameter of same                 3
  Transverse width of interclavicle          14
  Long diameter of same                       7(?)
  Long diameter of clavicle                   9
  Greatest transverse diameter                3
  Length of humerus                          10
  Greatest diameter of same                   4
  Least diameter of same                      1.5
  Length of radius (ulna?)                   11
  Length of vertebral centrum                 2
  Width of same                               3


=Genus CEPHALERPETON Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 340, 1912.

Type: _Cephalerpeton ventriarmatum_ Moodie.

This genus is founded on remains of a nearly entire individual of a
relatively large microsaurian from the Mazon Creek shales. The genus is
most immediately related to the Amphibamidæ, of which two species are
already known, _Amphibamus grandiceps_ Cope and _A. thoracatus_ Moodie.
The present genus differs from these species in many respects, notably
in size. The skull in _Cephalerpeton_ is nearly as long as half the
entire body of _Amphibamus grandiceps_ Cope, inclusive of the tail. Other
structural differences are the anisodont teeth, the large size and the
more median position of the orbits, and the absence of the posterior
tympanic notch in _Cephalerpeton_. The form of the skull recalls that
of _Melanerpeton_ and _Pelosaurus_ (190) of Europe, but those genera
are branchiosaurian, while the present form, from the structure of the
vertebræ and the long, curved ribs, is an undoubted microsaurian. Nothing
like it occurs in any of the amphibian faunas thus far made known. It is
most nearly approached by a member of the genus _Erpetosaurus_, but from
this genus the present form is readily distinguished by the smooth skull
bones, the absence of a posterior table to the skull, and the presence of
a highly developed ventral armature. The interorbital width is less than
the transverse diameter of the orbit.

[Illustration: MOODIE                                           PLATE 18

  1. Type specimen of _Erpelosaurus sculptilis_ Moodie, from the
       Cannelton Shales of Pennsylvania. Original in the University of
       Chicago, Walker Museum.

  2. Skeletal elements of _Eryops_ sp. indet., from the Pittsburgh Red
       Shale at Pitcairn, Pennsylvania. _a_=nearly complete vertebra;
       _b_ and _c_=ribs; _d_=pleurocentrum; _f_=neural arch and spine.
       Originals in the Carnegie Museum at Pittsburgh. After Case.

  3. Photograph of amphibian footprints, _Dromopus aduncus_ Branson,
       from the Mississippian shales of Giles County, Virginia. × 1/3.
       Courtesy of Dr. Branson. Original in the Museum at Oberlin
       College.

  4. Photograph of type of _Thinopus antiquus_ Marsh, the amphibian
       footprint from the Devonian of Pennsylvania. × 1/4. Courtesy of
       Dr. Lull. Original No. 784, Vale University Museum.

]


=Cephalerpeton ventriarmatum Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VII, No. 2, pp, 350-352, pl. 1, fig.
    4; pl. 7, fig. 2, 1912.

Type: Specimen No. 796, of Yale University Museum.

Horizon and locality: Collected at Mazon Creek in 1871, near Morris,
Illinois.

The remains on which the present species is based consist of an almost
entire skull, 26 consecutive vertebræ, both fore limbs, 20 ribs preserved
on the right side of the body, and a portion of the ventral armature
(plate 4, fig. 4).

The skull is very broad posteriorly, its width being one-third greater
than its length, with due allowance for crushing. A pineal foramen is
not preserved. The sutures bounding the premaxillaries, the maxillæ, the
nasals, the prefrontals, the frontals, a portion of the parietals, the
squamosal, the supratemporal, the quadratojugal, and the quadrate (?) are
fairly well preserved. The arrangement of these elements can be discerned
by reference to figure 29. The prefrontals are unusually large and are
triangular in shape. The supratemporal is also quite large. The surface of
the skull bones is smooth and there is nowhere an indication of sculpture.

[Illustration: Fig. 29. Skeleton of _Cephalerpeton ventriarmatum_ Moodie.
× 1.

_pf_, prefrontal; _cl_, clavicle; _m_, mandible; _h_, humerus; _j_, jugal;
_mx_, maxilla; _or_, orbit; _ph_, phalanges of hand; _par_; parietal;
_po_, postorbital; _r_, radius; _sp_, sclerotic plates; _u_, ulna; _vs_,
ventral scutellæ.]

Portions of 4 sclerotic plates are preserved in the right orbit. These
measure 0.5 by 0.75 mm. The orbits are large and the interorbital space is
less than the transverse diameter of the orbit. Thirteen teeth, apparently
pleurodont, are preserved on the left maxilla. They are short, sharply
pointed, smooth, and unequal. The first 2 left maxillary teeth from the
anterior end are short; then follows a tooth which is one-third longer
than these two; the fourth tooth is somewhat shorter than the third; the
fifth and sixth are still shorter and are practically equal in size,
though somewhat larger than the first two.

The right mandible is preserved almost entire, though so badly eroded that
little can be said of its structure. Impressions of 12 teeth are present
on the mandible and all are, apparently, equal. The cotylus seems to have
been far posterior and an angle of the mandible projected slightly back of
the skull.

There remain only a few indefinite impressions of the cervical vertebræ.
The union of the skull with the vertebral column is obscured and lost.
Impressions of the dorsal vertebræ are well preserved, and wax molds
made from these show the structure of the dorsal vertebræ surprisingly
well. They are long and cylindrical, with the median portions slightly
constricted by a deep pit on each side of the low neural ridge, which
takes the form observed in _Thyrsidium_, _Molgophis_, _Phlegethontia_,
_Dolichosoma_ (fig. 8) and other genera. The vertebræ are strongly
amphicœlous and the notochord was probably persistent. The sides of the
vertebræ are smooth.

The ribs are all intercentral in position; the anterior ones very broad
near the base, recalling the broadly expanded ribs described by Schwarz
(540) for _Scincosaurus_, _Ptyonius_, _Thyrsidium_, and other genera.
Posteriorly the ribs become slender and cylindrical. They are all rather
long and distinctly curved, with probably a cartilaginous tip.

There is preserved a single element of the right side of the pectoral
girdle. This is, I think, the coracoid, an element which has hitherto
escaped observation among the American Microsauria. It is long and
spatulate at both ends, with the median portion apparently almost
cylindrical, not unlike that described by Credner (181) for the coracoid
of _Branchiosaurus_, save that the lower end of the branchiosaurian
coracoid is acuminate. In the present form it is spatulate. Its
relations with the other elements of the pectoral girdle have never been
satisfactorily determined.

The fore limbs are both partially preserved. The humerus of the right
side is complete. It is greatly elongated for a microsaurian. The form
of the element is not unlike that of a lizard, with the lower end of the
bone spatulate and endochondrium well developed. Very little difference
can be seen between the form of the arm bones, which represent the radius
and ulna. They are both elongated, with constricted median portion and
expanded truncate ends. The carpus is unossified and the cartilage has
left no trace of the elements.

The right hand has two metacarpals preserved, which are fully half as long
as the radius and ulna. They are separated some little distance from the
ends of these elements, though this may be due to post-mortem shifting.
The carpus may, however, have been broad. On the left side are preserved
portions of the humerus, radius, ulna, and 3 metacarpals, lying close to
the vertebral column. The carpal space is not so large on the left as on
the right. The ventral armature is well preserved in a narrow patch about
an inch in length. The chevron-shaped rods are quite large, there being 2
of them in 1 mm.

Measurements.

                                                   mm.
  Entire length of fossil                          98
  Length of skull                                  22
  Width across base of skull                       28
  Long diameter of eye                             10.5
  Transverse diameter of eye                        8
  Interorbital space                                4
  Length of mandible                               26
  Depth of mandible at coronoidal region            3.5
  Depth of dentary                                  2
  Length of long tooth                              2
  Diameter of long tooth at base                     .5
  Length of preserved portion of vertebral column  64
  Length of a centrum                               3
  Median width of a centrum                         1.5
  Length of rib                                     6.5
  Width of rib at base                               .33
  Length of coracoid                                5
  Width of coracoid at anterior end                 2.5
  Length of carpal space                            5
  Length of humerus                                18
  Width of shaft                                    1
  Distal width of humerus                           4
  Length of radius and ulna                        10.5
  Length of metacarpal                              6
  Length of ventral armature preserved             24
  Number of rods in length of 5 mm                 10

[Illustration: MOODIE                                           PLATE 19

Type specimen of _Ctenerpeton alveolatum_ Cope, from the Coal Measures of
Ohio. × 1.33. Original in U. S. National Museum.]

[Illustration: MOODIE                                           PLATE 20

  1. Skull of _Erpetosaurus minutus_ Moodie, from the Cannelton slates
       of Pennsylvania. Original in U. S. National Museum. Enlarged ×
       3.3.

  2. Skull and anterior part of body of _Ptyonius pectinatus_ Cope,
       from the Coal Measures of Linton, Ohio. Original in U. S.
       National Museum. × 1.

  3. Skeleton of Eosauravus copei Williston, from the Coal Measures of
       Linton. Ohio. "The oldest known reptile from North America" and
       closely related structurally to the Microsauria. Original in U.
       S. National Museum. × 1.

  4. Part of the ventral scutellation and ribs of Sauropleura digitata
       Cope, from the Coal Measures of Linton. Ohio. Original in
       American Museum of Natural History. × 1.

]



CHAPTER XVIII.

THE MICROSAURIAN FAMILY NYRANIIDÆ, FROM THE COAL MEASURES OF OHIO.


=Family NYRANIIDÆ Lydekker, 1890.=

  Lydekker, Cat. Fossil Reptilia and Amphibia, p. 166, 1890.

  Skull with the palatines situated near the middle line, internally to
  the vomers and pterygoids, and the palatine vacuities small and placed
  far back. Vertebræ (_Ichthyerpeton_) discoidal. Teeth less complex
  than in the Anthracosauridæ. A ventral armor present and the entire
  body covered with small cycloid imbriated scales.

The type genus of this family was placed by Fritsch (251) with the
Archegosauridæ, although its resemblance to _Anthracosaurus_ was pointed
out; it was subsequently made the type of a family by Lydekker (393) in
1890, and placed next the Archegosauridæ. Known from the Coal Measures of
Bohemia, Ireland, and Ohio.

Two genera from North America, _Ichthyerpeton_ and _Cercariomorphis_, are
assigned tentatively to this family, both known from the Coal Measures
(462) of Linton, Ohio, and both with the body completely scaled. The
distinguishing characters are found chiefly in the shape and arrangement
of the scales, the structure, form, and size of the body, all of which are
given full treatment in the discussion below.


=Genus ICHTHYERPETON Huxley, 1866.=

  Huxley, Trans. Roy. Irish Acad., XXIV, p. 195, pl. xxiii, fig. 1;
    Scientific Memoirs, III, p. 195, pl. 23, fig. 1, 1866.

The genus was founded by Huxley (334) for the reception of the species
_Ichthyerpeton bradleyæ_ from the Kilkenny Coal Measures of Ireland. The
remains of the type specimen represent "the hinder moiety of the trunk,
with the greater part of the tail, of an animal whose scaly integument and
laterally compressed, fin-like tail might easily lead one to take it for a
fish, were not its true position among higher vertebrata settled at once
by the digitate hind limb; while its alliance with the labyrinthodonts
is indicated by the delicate spicular ossicles, which form a rudimentary
dermal shield along the belly." (Huxley.)


=Ichthyerpeton squamosum Moodie.=

  Moodie, Jour. Geol., XVII, No. 1, p. 69, 1909.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 24, 1909.

Type: Specimens Nos. 4476 and 4459, U. S. National Museum.

Locality and horizon: Linton, Ohio, Coal Measures.

The present species is based on well-preserved remains from the Linton,
Ohio, beds. There are two specimens of the species preserved on blocks
of coal and together they represent the greater part of the length of
the animal. The species is located in the genus Ichthyerpeton, which
was founded by Huxley (334, p. 351) on remains from the Coal Measures
of Ireland, on account of the character of the dermal covering, which
consists of small scales such as Huxley described in the form from
Ireland. The specific characters of this form are the small size of the
rounded scales, the attenuated tail, the apparent absence of limbs, the
character of the ventral scutellation, and the slightly curved condition
of the ribs.

It is estimated, from the portions preserved, that the animal attained
a length of not less than 3 feet and its body was long and slender. It
may have had an appearance similar to the modern caudate genus _Siren_,
though there were doubtless 4 limbs present instead of 2. The slenderness
of the body is at variance with the condition found in the type species
_Ichthyerpeton bradleyæ_ Huxley, in which the trunk was rather stoutly
built. The character of the anterior portion of the body in the present
species can not be determined and the skull is wanting. There are no
evidences of anterior limbs, although the ventral scutellation preserved
would seem to include the pectoral region. No pectoral shields are
preserved, nor are there any traces of pelvic girdle or limbs.

The preserved portions on one block include nearly the entire tail and the
posterior region of the body, and on the other block the dorsal region of
the body and the anterior portion of the tail, so that the two specimens
supplement each other in an interesting manner. There are impressions of
several vertebræ preserved. They are much the same in character as Huxley
has described for the type species (_I. bradleyæ_). They are short and
thick and were probably amphicœlous. There are likewise preserved the
remains of rather slender recurved ribs mingled in with the remains of the
ventral scutellation and distinguished from the elements of the abdominal
shield by their size and curvature. They are, apparently, single-headed,
but the character of their articulation can not be determined. The ventral
scutellation consists of fine continuous rods arranged in the regular
chevron pattern. They do not seem to be divided into oat-shaped scutes,
as is the case with the form described by Huxley. The ventral rods are
closely packed for a distance of more than 6 inches, but as they are
scattered their exact arrangement can not be determined. They seem to
have extended to the cloacal region, but there are no evidences of the
specialized clasping organs such as Fritsch (251) has described in the
ventral scutellæ of _Ophiderpeton_. The scales, which are well preserved
on the tail, may have covered the entire body, since there are many
scattered scales in the dorsal region of one of the specimens. They are
slightly oval, tuberculate, and measure scarcely 1 mm. in their longest
diameter. They show but slight evidences of having been imbricated,
though it is likewise possible that they were simply inclosed within the
integument, and somewhat separated from one another. The most posterior
part of the tail preserved seems to indicate that the tip was attenuated.
It was probably flattened from side to side. We may thus regard
_Ichthyerpeton squamosum_ as an elongate aquatic animal with a long,
flattened tail, and since there were possibly no limbs or very small ones,
it would be an animal highly adapted for life in the water. The present
species is of interest because it represents an additional discovery of
the scaled Amphibia in North America. The species previously known from
the Linton, Ohio, deposits is _Cercariomorphus parvisquamis_ Cope. Dermal
scales have also been observed in specimens of _Amphibamus grandiceps_
Cope and _Micrerpeton caudatum_ Moodie (462, 478) from the Mazon Creek,
Illinois, beds, and Sir William Dawson (208) described scales accompanying
several forms from the Joggins deposits of western Nova Scotia.

[Illustration: MOODIE                                           PLATE 21

  1. Mandible of _Micrerpeton deani_ Moodie, from the Linton. Ohio,
       Coal Measures. Original in American Museum of Natural History,
       No. 2934. × 0.6.

  2. Portion of the skull of _Micrerpeton deani_ Moodie, possibly of
       the same individual as the mandible. From the Linton, Ohio, Coal
       Measures. Original in American Museum of Natural History, No.
       3535 G. × 0.4.

  3. Type of _Cercariomorphus parvisquamis_ Cope, from the Linton,
       Ohio, Coal Measures. Original in American Museum of Natural
       History. × 1.

  4. An additional specimen of _Cercariomorphus parvisquamis_ Cope,
       from the Linton, Ohio, Coal Measures. Original in American Museum
       of Natural History. × 1.

  5. Skull of _Sauropleura scutellata_ Newberry. From the Coal
       Measures of Ohio. × 1.

  6. Tooth of _Mastodonsaurus_ sp. indet. of the Carboniferous of
       Kansas. Original in University of Kansas Museum. × 1.

  7. Tooth of _Mastodonsaurus giganteus_ Jaeger, from the Triassic of
       Germany. Introduced for comparison with the tooth from the Kansas
       Carboniferous. × 1.

]

Measurements of the Types of Ichthyerpeton squamosum Moodie.

  Length of animal as estimated from two impressions    3 ft.
  Length of longest impression                         21 in.
  Length of specimen containing tail impression         9 in.
  Width of tail impression: Maximum                    50 mm.
                            Minimum                     6 mm.
  Width of a single scale                               1 mm.
  Distance from base of tail to tip                   125 mm.
  Length of specimen as preserved                     225 mm.
  Width of chevron rod space                           30 mm.
  Length of rib                                        25 mm.
  8 chevrons in a distance of                           3 mm.


=Genus CERCARIOMORPHUS Cope.=

  Cope, Proc. Amer. Phil. Soc., 1885, p. 405.

Type: _Cercariomorphus parvisquamis_ Cope.

The type specimen of this genus is supplemented by a portion of the body
of another specimen which adds a little to our knowledge of the animal's
form, but nothing as to structure. Cope's original description is as
follows:

  "Represented by a fusiform body which terminates in a long, slender,
  cylindrical tail, and which is covered with small subquadrate scales
  quincuncially arranged. No fins or limbs are preserved, and the form
  of the head can not be made out. Probably a portion of the skull
  is preserved. There are some scattered bodies in the body portion,
  which look like deeply concave vertebræ with the zygapophyses of
  batrachians. There are some linear impressions at one point, which
  resemble the bristle-like rods on many Stegocephali. They are so few
  as to be of little importance. The scales are like those of fishes.
  There are traces of segmentation in the axis of the long tail.

  "The position of this curious form is quite uncertain. It is quite
  different from anything observed hitherto in the American Coal
  Measures."


=Cercariomorphus parvisquamis Cope.=

  Cope, Proc. Amer. Phil. Soc., 1885, p. 405.

  Moodie, Science, n.s., XLI, No. 1056, p. 463, 1915.

Type: Specimen No. 2560, Newberry Collection, American Museum of Natural
History.

Horizon and locality: Discovered by Samuel Huston at the Linton, Ohio,
Coal Mines. (Plate 21, figs. 3, 4; 24, figs. 2, 3.)

The scales (Plate 24, fig. 2) in their present condition are entirely
smooth. At a distance of 20 mm. from the base of the tail they are in 20
longitudinal series. At that point the transverse diameter of the body is
140 mm. The outline contracts rather abruptly to the tail, of which 66
mm. are preserved. The surface of the tail is obscured by a thin layer
of carbonaceous matter not sufficiently thick to obscure scales, which
are evident at distances of 16 mm., 43 mm., and 52 mm. from the tip. The
scales on the tail are smaller than those on the body and are without
markings of any kind. The anterior half of the body is depressed and
distorted, but the remainder is well preserved and shows a fairly good
outline of an apparently limbless body.

An additional specimen (No. 8683 G, of the Newberry Collection, American
Museum of Natural History) reveals no new facts as to structure, but
serves to show that the body of the animal was long and slender (plate
21, fig. 4). The portion studied comes undoubtedly from the middle of the
body. No limb elements are preserved. The scales are somewhat larger,
especially toward the sides of the body, than in the type. The fragment
measures 70 mm. in length by 18 mm. and 26 mm. in width. One of the
largest scales measures 1 mm. in diameter.

Measurements of Type.

  mm. Length of entire remains 180 Greatest width 22 Greatest width of
  undisturbed portion 15 Length of an individual scale .75



CHAPTER XIX.

THE AISTOPODOUS MICROSAURIAN FAMILY PTYONIIDÆ, FROM THE COAL MEASURES OF
OHIO.


=Family PTYONIIDÆ Cope, 1875.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 357, 1875.

  Elongate, slender, weak-limbed, aquatic microsaurians. Neural and
  hæmal spines of vertebræ elongated, expanded and sculptured. Ventral
  armature weakly developed or absent. Skull lanceolate, with long,
  slender teeth.

Three genera are assigned to this family: _Ptyonius_, _Œstocephalus_, and
_Thyrsidium_. The forms are very closely related, and when additional
material is secured the three genera may be found to be identical. The
species included in this family are: _Ptyonius pectinatus_ Cope, _P.
vinchellianus_ Cope, _P. marshii_ Cope, _P. nummifer_ Cope, _P. serrula_
Cope, _Œstocephalus remex_ Cope, _O. rectidens_ Cope, _Thyrsidium
fasciculare_ Cope. The species are all exclusively from the Linton, Ohio,
Coal Measures, and most of them are known from abundant material.


=Genus PTYONIUS Cope, 1875.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 373, 1875.

Cope designated no species as the type, but we may regard _Ptyonius
pectinatus_ as typical.

Form elongate, with long tail and lanceolate cranium. Limbs weak, a
posterior pair only discovered. Three clavicular elements; abdomen
protected by packed osseous rods, which are arranged _en chevron_, the
angle directed forward. Neural and hæmal spines of caudal vertebræ
expanded and fan-like. Ribs well developed. The various species vary in
length from 3 to 10 inches. They are the most abundant amphibian in the
Linton beds. The present genus resembles _Lepterpeton_ Huxley (334), of
the Kilkenny, Ireland, Coal Measures. But that genus possesses divided
abdominal rods, or "oat-shaped scales," and the form of the cranium and
proportions of the body are different.

The genus is closely related to, possibly identical with, _Œstocephalus_,
but additional material will be required to settle this point.

Cope (123) gives the following key for the separation of the 5 species:

 x. Abdominal rods coarser, not more than 10 in 5 mm.
     Median pectoral shield discoid, radiate-ridged;
       muzzle short   _P. nummifer_
     Median pectoral shield oval, pitted and ridged            _P. marshii_

xx. Abdominal rods hair-like, 15 or more in 5 mm.
      Median pectoral shield with radii from the center,
        the principal forming a cross; form wider        _P. vinchellianus_
      Middle pectoral with pits at the center and few or
        no radii; form narrow                               _P. pectinatus_
      Middle pectoral shield narrow, closely reticulate
        medially, and radiate towards the circumference;
        size half that of last                                 _P. serrula_


=Ptyonius pectinatus Cope.=

  Cope, Proc. Acad. Nat. Sci., 1868, p. 216.

  Cope, Trans. Am. Phil. Soc., XIV, p. 20, 1869.

  Cope, Trans. Am. Phil. Soc., XV, p. 266, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 377, pl. xxvii, fig. 7; xxviii,
    figs. 2, 3, 6; pl. xxix, fig. 2; pl. xxx, fig. 2; pl. xxxv, figs. 1-3;
    pl. xli, fig. 1, 1875.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 24, pl. 8, fig. 3, 1909.

  Schwarz, Beiträge zur Paleontologie und Geologie Osterreich-Ungarns
    und des Orients, Bd. XXI, p. 83, figs. 23, 24, 26, 1908.

Type: It is impossible to determine which one of the specimens is the
type. There are numerous representatives of the species, as follows: Nos.
140, 1096 G, 8345 G, 8555 G, 1089 G, 2, 132, 133, no number, 1094 G, 8545
G, 8677 G, 1159 G, 105, no number, 1091 G, 7_a_, 1092 G, 1093 G, 1095 G,
153, and others unnumbered in the American Museum of Natural History; in
the U. S. National Museum are the following: Nos. 4458, 4463, 4464, 4514.
(Plate 20, fig. 2.)

Horizon and locality: Linton, Ohio, Coal Measures.

The most abundant species of the Linton Coal Measures. There are over
three dozen specimens preserved in the Newberry collection. The species is
a clearly marked one, as a rule, though there is great variation in the
size of the body and the form of the vertebræ. Though there are several
apparently complete skulls preserved in the collection, it is impossible
to make out the morphology of the elements on account of the amount of
crushing to which the skulls have been subjected.

[Illustration: Fig. 30. Restoration of _Ptyonius_. × 1.]

The head is lancet-shaped, and the muzzle very elongate, slender, and
acute at the extremity. The head is in fact a miniature of an ichthyosaur
cranium. (Plate 20, fig. 2.) The orbits are large and posterior to the
median line. The anterior portion of the skull is narrow, posteriorly
truncate, and the mandibular angle is projecting. The posterior portion
of the mandible is sculptured. Possibly the entire cranium was also, and
this has been lost; in fact, this sculpturing is indicated in one or two
specimens. The teeth are conical and sharp, longitudinally striate, and
anisodont. There seems to be evidence of palatine or pterygoid teeth,
though this needs confirmation. The pectoral plates are well preserved,
with the interclavicle a narrow oval, with anterior and posterior
prolongations. In one specimen it is sculptured. The clavicles are narrow
and slightly sculptured. The abdominal scutellæ are bristle-like.

The vertebræ are short, with expanded neural and hæmal spines. The
expanded condition of the neural spines begins over the thoracic region,
where they are low. They become well developed in the posterior dorsal
region. The caudal fan-shaped spines are larger. The dilated portions
form equilateral triangles which stand on moderately short pedicels. They
are weakly ridged, and each ridge is prolonged into a narrow acute tooth
beyond the margin, 11 of which may be counted on one of the best preserved
spines. The longitudinal striæ are terminated near the pedicel by two
others which cross obliquely from each side, and, meeting, present the
appearance of the margin of a cup sculptured in relief, from which the
striæ arise. Pedicels smooth. The spines are in contact at their angles,
thus forming a continuous line. In a typical specimen there are 6 in half
an inch, in another 7, and in a third 8. The ribs are well-developed and
slender.

No traces of fore limbs have been detected in the numerous specimens, but
elements of hind limbs are preserved. In one of these the femur is a small
bone, contracted at the middle. The form of the body is snake-like.

There were probably from 75 to 100 vertebræ in a single animal. The form
may be well compared to the modern _Amphiuma_ so far as appearances are
concerned; structurally they are widely separate. This species is one
which is peculiarly characteristic of the Linton fauna.

Measurements of Ptyonius pectinatus Cope.

  _Nos. 107 and 1094 G, American Museum._

                                mm.
  Length of specimen           137
  Length of skull               26
  Posterior width of skull       8
  Interorbital width             3
  Diameter of orbit              1.5
  Vertical expanse of vertebra   6
  Width of neural fan            2
  Diameter of pedicel            1

  _Measurements of a small jaw, No. 8555 G, American Museum._

                                mm.
  Length of jaw                 15
  Greatest width                 1.5
  Length of tooth                1

  _Measurements of specimen No. 4438, U. S. National Museum._

                                mm.
  Length of specimen            65
  Length of skull               22
  Width of skull                 6


=Ptyonius vinchellianus Cope.=

  Cope, Proc. Am. Phil. Soc., p. 177, 1871.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 376, pl. xxviii, fig. 1, 1875.

Type: Specimen in the American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The species is represented by the opposite halves of a single specimen,
which includes only the cranium and anterior half of the body. The
fan-shaped neural spines commence but a short distance behind the line
of the pectoral shields. They are low, with a few coarse ridges, the
margin being entire. The abdominal rods are delicate and hair-like. The
interclavicle is oval, with a few radiating crests, which originate at
the center; in the areas behind there are a few scattered tubercles. The
clavicles are ridged near the margin.

The cranium is lanceolate in form, and the bones of the dorsum are marked
with a few raised points and ridges. The species is about the size of
_Ptyonius pectinatus_ Cope, and differs, apparently, from that species in
the rather insignificant character of a narrower interclavicle and in the
ornamentation of the same. Dedicated to Professor Alexander Winchell, of
the University of Michigan.

Measurements of Ptyonius vinchellianus Cope.

                                mm.
  Length of cranium             20
  Width of same                  8
  Length of interclavicle        4-2


=Ptyonius marshii Cope.=

  Cope, Trans. Amer. Phil. Soc., XIV, p. 24, 1869 (_Colosteus marshii_).

  Cope, Geol. Surv. Ohio, II, pt. II, p. 375, pl. xxvii, fig. 6; pl.
    xxviii, fig. 3, 1875.

  Cope, Proc. Am. Phil. Soc., XII, p. 177, 1871.

Type: Specimen No. 1157 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The head is elongate lanceolate. The upper surface of the frontal bones is
punctate-rugose in relief, with short radii toward the margin. The distal
two-thirds of the mandible is narrow wedge-shaped; the external surface
is coarsely pitted. There are no teeth preserved. The pectoral elements
are displaced, but the clavicles are subtriangular, and are strongly
ridged toward the inner margin. The interclavicle is short spatulate, the
narrow portion directed anteriorly; the posterior rounded. It is coarsely
pitted medially, and coarsely and strongly radiate-ridged to the margin.
The abdominal armature commences immediately behind the pectoral girdle.
It consists of elongate, narrow, subcylindric scales, which meet on the
median line, converging anteriorly. Small limbs are present.

Measurements of Ptyonius marshii Cope.

  Type specimen:                                mm.
    Length of fragmentary skull                  7
    Width of skull as preserved                  5
    Length of entire specimen                   68
    Width across pectoral plates                 8
    Width across belly                           7

  Specimen No. 1098 G, American Museum:
    Length of specimen                          32
    Width of specimen                            7
      4 scutes of abdominal armature in 1 mm.


=Ptyonius nummifer Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, pp. 374, 375, pl. xli, figs. 2 and
    3, 1875.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, p. 356, pl. 63, fig. 3, 1909.

Type: Specimen No. 8546 G, American Museum of Natural History. No. 8614 G,
same museum, is associated with the type specimen.

Horizon and locality: Linton, Ohio, Coal Measures.

Two well-preserved individuals display peculiarities which indicate
specific distinctness from the previously known species of _Ptyonius_.
The abdominal rods are of the coarse type of those of _P. marshii_. The
caudal fans are well developed, and not so wide as in _P. pectinatus_.
The interclavicle is a discoid body of different form from that of _P.
marshii_ and I can not detect the clavicles. The sculpture consists
of strong ridges, which radiate from the center to near the border.
Immediately in front of this interclavicle is the head, which has a
different form from that of the other known species. The interorbital
width is two-thirds the long diameter of the orbit. The structure of the
skull can not be made out. A slender, elongate hind limb is present in the
second specimen, and a humerus is well preserved in the type.

Measurements of the Type of Ptyonius nummifer Cope.

(No. 8546 G, American Museum of Natural History. No. 8614 G is associated
in the same species.)

                                         mm.
  Length to beginning of caudal fans     65
  Length of head                         15
  Length from muzzle to orbits            6
  Length of interclavicle                 7
  Width of interclavicle                  8
  Width of abdominal armature             8
  Length of a caudal fan                  2.5
  Length of femur                         5
  Proximal width of femur                 1.5


=Ptyonius serrula Cope.=

  Cope, Proc. Am. Phil. Soc., 1871, p. 177.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 379, pl. xxviii, fig. 5; pl.
    xxx, fig. 1, 1875.

Type: Specimen No. 8615 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The specimens of this species indicate that the form was only about half
the size of _Ptyonius pectinatus_. The interclavicle is narrower and more
reticulately sculptured. The tail is relatively longer. Abdominal rods
hair-like. Ribs distinct. Small limbs are present in one specimen.

Measurements of Cope's Type of Ptyonius serrula.

                                          mm.
  Length of specimen                      95
  Length of portion of skull preserved     3
  Length of interclavicle                  4.5
  Width of interclavicle                   2
  Length of clavicle                       4
  Width of clavicle                        1.5
  Length of vertebra                       1
  Width of vertebra from tip of neural
    spine to tip of hæmal spine           4

Another specimen (456 G, American Museum of Natural History) shows some
of the same characters. There is not the slightest basis for the support
of this species, so far as I can observe. The ones mentioned by Cope are
insufficient. It is in all probability a mutant or variety of _Ptyonius
pectinatus_.


=Genus ŒSTOCEPHALUS Cope, 1868.=

  Cope, Proc. Phila. Acad. Nat. Sci., 218, 1868.

  Cope, Trans. Amer. Phil. Soc., XIV, 16.

  Cope, Proc. Phila. Acad. Nat. Sci., 1868, 217.

  Cope, Proc. Amer. Phil. Soc., 1871, 41.

  Cope, Geol. Survey Ohio, II, pt. II, 380, 1875.

Type: _Œstocephalus remex_ Cope.

Form slender and snake-like; caudal vertebræ with elongated, dilated,
sculptured neural and hæmal spines. Cranium lanceolate. Teeth numerous,
of nearly equal size. No pectoral shields known; abdomen protected by
very numerous bristle-like rods, which converge forwards. A pair of weak
posterior limbs; branchihyal bones present.

In the only well-preserved species the cranial bones exhibit no sculpture
from the parietal region forward. The genus is not very distinct from
Ptyonius, but it can not be united with that genus until more complete
material is available. The species of the genus share with _Ceraterpeton_,
_Urocordylus_ (334), and _Ptyonius_, as well as _Crossotelos_ (98), from
the Permian of Oklahoma, the elongation, sculpture, and expansion of the
neural and hæmal spines. There are but 2 species, which Cope distinguishes
by the following characters:

   I. Vertebræ elongate; fan-like caudal processes narrowed. Size
        large; mandibular teeth of unequal lengths, with the apices
        turned backward                                _Œstocephalus remex_

  II. Species only known from cranial bones with teeth. Teeth equal,
  erect, with acute conic apices, 11 in 5 mm       _Œstocephalus rectidens_


=Œstocephalus remex Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 217, 1868 (_Sauropleura remex_).

  Cope, Proc. Phila. Acad. Nat. Sci., p. 218, 1868 (_Œstocephalus
    amphiumianus_).

  Cope, Trans. Amer. Phil. Soc., XIV, p. 17.

  Cope, Geol. Surv. Ohio, vol. II, pt. II, p. 381, pl. xxvii, fig. 5;
    pl. xxxi, fig. 1; pl. xxxii, fig. 1; pl. xxxiii, fig. 2; pl. xxxiv.
    fig. 4, 1875.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909.

Type: Specimen undetermined. The following specimens are to be found:
Specimens of _Œstocephalus remex_ Cope in the National Museum, Nos.
4511, 4460, 44/8. There is one specimen of _Œstocephalus remex_ in the
University of Chicago. Specimens of the species in the American Museum of
Natural History: Nos. 121, 8322 G, 8694 G, no number, 8656 G, 8583 G, 8659
G, 19, 120, 8655 G, 8662 G, 8708 G, 8665 G, 112, 8663 G, 8581 G, 8658 G,
8660 G, 8700 G, 8469 G, 1102 G, 1152 G 142, 8381 G, and obverse, 21, 8664
G, 8672 G, 8592 G, 8684 G.

Horizon and locality: Linton, Ohio, Coal Measures.

This species is one of the most abundant of the Linton Amphibia. Cope
based his description of the species on 9 specimens. There are more than
two dozen available at the present time, the majority of them being in the
possession of the American Museum of Natural History. There is a single
specimen in Walker Museum of the University of Chicago and 3 in the United
States National Museum. The numbers of all of these specimens are given
above. The material consists, for the most part, of fragmentary portions
of the vertebral column, but there are a few skulls more or less complete,
though none are sufficiently well preserved for a complete analysis of the
characters. The specimens indicate an animal slightly smaller than the
modern _Amphiuma_ means of the Mississippi River.

[Illustration: Fig. 31. Restoration of _Œstocephalus_. × 1.]

It will not be necessary here to enter into a detailed account of each
specimen, since this has been done by Cope, and a careful comparison of
his descriptions with the originals indicates that his observations are
correct. The species, as suggested in the discussion of the genus, is
not clearly distinct from those of _Ptyonius_, and it has largely the
characters of that genus. The cranium is long, slender, and wedge-shaped.
The teeth are numerous both in the maxillary and in the mandible, one
specimen indicating about 30 in a single series. They are all uniformly
cylindrical, except at the extremity, where they are flattened and
expanded so as to produce a longitudinal edge, which is carried backward
on a recurvature of the apex. The bases are anchylosed equally and without
enlargement, and no part of the shaft is striate or grooved. The upper
surface of the cranium is narrow, with the median suture distinct. The
skull surface, with that of the mandible, is smooth.

Characteristic of the species are the remarkable length and slenderness
of the fan-shaped neural and hæmal spines, and the absence of an acute
serration on their margins. In this species the spines have a laminiform
expansion at the base in their plane. One specimen exhibits the pelvic
region, including a portion of the tail. The ilium has an expanded
anterior extremity and is directed backwards and somewhat inwards on
either side of the vertebral column. The femur is nearly straight, short,
contracted medially, and expanded distally. The tibia is shorter and is
subcylindrical. Beneath the ilium the last chevron of the abdominal rods
appears, the outer extremities rising on the base of the tail.

The pectoral arch is almost unknown, and Cope based the distinction of
_Ptyonius_, and _Œstocephalus_ on the absence of these plates in the
latter genus an uncertain characterization. The fore limbs are indicated
by a humerus. There were possibly from 75 to 100 vertebræ in the entire
column. The animal was exclusively adapted to life in the water and was,
without doubt, an excellent swimmer. There are preserved in one specimen
portions of what seem to be hyobranchial elements.

Measurements of Œstocephalus remex Cope.

                                        mm.
  Length of entire caudal series       195
  Width at ninth vertebra               21
  Width at thirty-sixth vertebra         2
  Length of four phalanges in place     14
  Expanse of fan of proximal caudal     18.5
  Length of ilium                       11.5
  Length of femur                       11.5
  Length of tibia                        7
  Length of mandibular dental series    24
  Depth of mandible at middle            5
  Nine teeth in                          5
  Length of longer teeth                 2
  Length of first hæmal branchial       6
  Length of sixth vertebra from skull    7
  Width of centrum                       3


=Œstocephalus rectidens Cope.=

  Cope, Trans. Amer. Phil. Soc., p. 268, Apr., 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 386, pl. xxvii, fig. 3, 1875.

Type: Specimen No. 9033, American Museum of Natural History, collection of
J. S. Newberry.

Horizon and locality: Linton, Ohio, Coal Measures.

The species is indicated by a left dentary bone, with its teeth and
external surface preserved. The latter is nearly smooth and without
sculpture. The outer face is convex, and the general form is slender, but
not curved upward at the extremity. The extremity of the dentary does
not show any evidences of teeth. Teeth straight and conic, apex acute,
non-plicated.

Cope also associated with this species a portion of a caudal series,
consisting of 25 vertebræ. The centra are elongate and expanded at the
extremities. The neural arches have a close union. The neural and hæmal
spines are fan-shaped and striated. The bases are quite narrow.

Measurements of Œstocephalus rectidens Cope.

                                           mm.
  Length of dentary                        22
  Length of tooth line                     15.2
  Depth of dentary at last tooth            2.7
  Length of 3 centra of the caudal series   8.6
  Extent of neural and hæmal spines        8.7


=Genus THYRSIDIUM Cope, 1875.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 365, pl. xxxi, fig. 2, 1875.

Type: _Thyrsidium fasciculare_ Cope.

Established on a species which presents its principal peculiarities in the
structure of the vertebræ. Two specimens present inferior views of the
spinal column, showing that the genus possesses, like _Siren_, enlarged
diapophyses, but they are peculiar in their fan-like form. They resemble
slightly the neural spines of the caudals of _Ptyonius_, but are present
on the dorsal vertebræ. Whether the caudals of the present species possess
ornamented neural spines the specimens do not indicate. The abdomen is
protected by the usual hair-like rods arranged _en chevron_, the angle
directed forwards. No indications of limbs can be discovered on the
blocks.

Without the cranial bones the affinities of this genus can not be
determined; while it may be allied to _Cocytinus_, the vertebræ of that
form are without peculiar diapophyses.


=Thyrsidium fasciculare Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 365, pl. xxxi, fig. 2, 1875.

Type: Specimen No. 8552 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The best preserved example of this species includes 9 vertebræ and the
corresponding ventral armature. The centra, seen from below, are much
contracted in their form, presenting an obtuse median rib, which expands
to the articular extremities. In one or two instances the latter are
divided by fracture, and the moderately concave form of the adjacent
surfaces is displayed. The diapophyses are of complex form, but the
details are concealed by the prevalent thin layer of coal which invests
them. An inferior prominence runs parallel to the centrum; outside of this
the process is obscurely trilobate and thickened, not flattened, as in the
caudal vertebræ of _Ptyonius_. Several ribs (fig. 8) of moderate thickness
appear by the side of the diapophyses. Eleven abdominal ribs in 5 mm.

The second specimen was originally referred to _Œstocephalus remex_, as
a posterior portion of its vertebral column, immediately preceding the
caudal series.

This reference appears to be incorrect, although the resemblance between
the corresponding parts in the two genera is no doubt considerable, and
the alternative of proposing a new genus and species was not at that time
advisable.

The neural spines are longer than high, and are nearly in contact at their
margins; each is marked by about 5 obtuse vertical ribs. A fractured
section of the abdominal spines in place displayed at least six layers of
them.

The material on which the above account is based is imperfect. The
specimen figured by Cope (Geol. Surv. Ohio, vol. II, pt. II, pl. xxxi,
fig. 2, 1875) is undoubtedly a portion of the vertebral column of
_Œstocephalus remex_. Nos. 4462 and 4480 of the United States National
Museum may be representatives of _Thyrsidium fasciculare_, but they are
more probably _Œstocephalus remex_; if they are the latter this leaves the
type as the only known specimen of the species.

Measurements of Type of Thyrsidium fasciculare Cope.

                                                     mm.
  Length of portion of vertebral column preserved     7
  Width of ventral armature                          18
  Length of a vertebra                                9
  Width of same vertebra                              4



CHAPTER XX.

THE MICROSAURIAN FAMILY MOLGOPHIDÆ, FROM THE COAL MEASURES OF OHIO AND
MAZON CREEK, ILLINOIS.


=Family MOLGOPHIDÆ Cope, 1875.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 157, 1875.

  Cope, Bull. U. S. Nat. Mus., No. 1, p. II, 1875.

Type of family: _Molgophis_.

  Body long, serpentine, a few species apparently limbless, ribless, and
  with abdominal armature lacking. Vertebræ elongate, neural and hæmal
  spines short or absent. Ribs long, heavy, and broad. The vertebræ
  seem to bear the characteristic marks of the family. One species has
  the skeleton reduced to a lanceolate skull and a string of about 50
  slender vertebræ, all the rest of the skeleton being absent. The
  family is very poorly known, but was apparently of wide distribution
  in North America and confined to this continent. The representatives
  of the group are known from Iowa, Illinois, and Ohio.

Four genera are assigned to the family, but future discoveries will
undoubtedly demand revision of the present classification. The genera
are _Molgophis_, _Pleuroptyx_, _Phlegethontia_, and _Erpetobrachium_.
The distinguishing characters of these genera are apparent from the
descriptions of the various forms. The skeletons of the species are too
incompletely known to allow the establishment of a tabular key to the
genera.


=Genus MOLGOPHIS Cope, 1868.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 220, 1868.

  Cope, Trans. Amer. Phil. Soc., XIV, p. 20, 1869.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 368, 1875.

  Cope, Trans. Amer. Phil. Soc., XV, p. 263, 1874.

Type: _Molgophis macrurus_ Cope.

Cope (123) gives the following:

  "The characters of this genus are: body long, serpentine, without
  dermal armature, so far as known; vertebræ long and broad, with very
  prominent zygapophyses and moderate neural spines; ribs large, curved.
  No limbs or cranium can be ascribed to the type of the genus. The ribs
  are long, and though the head is not bifurcate, there appears to be
  both tubercle and head on the dilated extremity. Where crushed they
  display a large median vacuity.

  "This genus differs from Ophiderpeton Huxley (334) in the characters
  of the dorsal vertebræ, which, in their projecting zygapophyses,
  resemble those of Amphiuma. The lack of ventral armature distinguishes
  it from _Œstocephalus_, while its well-developed ribs separate it from
  _Phlegethontia_."


=Molgophis macrurus Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 220, 1868.

  Wyman, Am. Jour. Sci. and Arts, p. II, fig. 1, 1858 (refers to a
  batrachian reptile).

  Cope. Trans. Amer. Phil. Soc., XIV, p. 20, 1869.

  Cope, Trans. Amer. Phil. Soc., XV, p. 263, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 368, pl. xliii, fig. 1, 1875.

Type: Specimen No. 8617 G, American Museum of Natural History, collection
of Dr. J. S. Newberry.

Horizon and locality: Linton, Ohio, Coal Measures.

This species is established by remains of 2 individuals, one embracing
16 and the other 14 vertebræ, with ribs. The neural arches, viewed from
above, have a =V=-shaped outline posteriorly, from the fact that
the broad zygapophyses meet on the median line and spread out distally
over the broad anterior ones adjoining. The latter appear to be somewhat
concave and to border the former exteriorly as well as inferiorly. The
base of the neural spine extends to the posterior emargination, but not
quite to the anterior. The breadth of the dorsal vertebræ above is equal
from the emargination behind to the anterior margin of the anterior
zygapophyses.

The ribs are long for an amphibian, but not long for a reptile. They are
well curved, chiefly near the proximal extremity. The longest found,
measured by a cord, equals two and two-fifths vertebræ. These vertebræ,
measured along the median line above, equal 11 lines; one of these is 3.6
lines in width above. This animal has been, like _Amphiuma_, a snake-like
amphibian, but was probably still larger. How near the affinities to
this genus may be can not now be determined, owing to the want of many
important parts of the skeleton, but it differs in the important feature
of large, well-developed ribs. The size of the vertebræ would indicate a
body of the size of the common rattlesnake (_Crotalus horridus_) and too
large for _Brachydectes newberryi_, which is only known from jaws.

[Illustration: Fig. 32.--Drawing from Cope's figure of _Molgophis
brevicostatus_ Cope, × 0.5]


=Molgophis brevicostatus Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 369, pl. xliv, fig. 1, 1875.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909.

Type: Specimen No. 8341 G, Amer. Mus. of Nat. History.

Horizon and locality: Linton, Ohio, Coal Measures.

Represented by portions of the vertebral column of several individuals.
One of these includes 9 pairs of ribs, with vertebræ, and another 13
pairs. The vertebræ are subquadrate in section, and the concavity of
the two articular faces is not deep. They support strong lateral ridges
separated by deep concavities. The heads of the ribs are somewhat
contracted, and the shafts present outward a tubercular angle at a
distance of one-fourth the length from the head. The remaining part
of the shaft is stout, nearly straight, and gradually contracts to an
obtuse extremity. It possesses a narrow medullary cavity. In none of the
specimens is there any trace of abdominal armature, but abundant remains
of the contents of the abdominal cavity, in proper position, are preserved
on the blocks. This species is more massive than Molgophis macrurus, and
the ribs are shorter, thicker, and less curved.

Ventral scutellæ are present in one specimen of this species. There are
a number of specimens. They have the following numbers at the American
Museum: 158, 1100 G, no number, 8341 G (type), no number, 8466 G; and 4477
in the U. S. National Museum.

Measurements of Type Specimen of Molgophis brevicostatus Cope.

                                 mm.
  Length of 7 vertebræ           105
  Length of 1 centrum             16
  Diameter of same vertically     11
  Length of a rib on a curve      24
  Greatest thickness of same       2.5


=Molgophis wheatleyi Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, pp. 369, 370, pl. xlv, fig. 1,
    1875.

  Cope, Trans Am. Phil. Soc., XV, p. 263, 1874.

Type: Specimen No. 1101 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

A critical study of the type specimen of this species does not reveal
anything essentially different from the description of Cope. The following
is taken from his report (123):

  "Established on a specimen which exhibits about twenty-five vertebræ
  with ribs, and the posterior portion of the cranium. No traces of
  abdominal scales or rods, thoracic shields, or limbs are visible. By
  such negative characters it is referable to the genus _Molgophis_,
  although the definition of this genus is incomplete. The present
  batrachian may, indeed, be ultimately found to be an _Ophiderpeton_,
  to which it also bears some resemblance.

  "The specimen is that of an animal of very much smaller size than the
  _M. macrurus_. The vertebræ are of moderate length, with a low neural
  spine, and centrum angular at the sides and truncate at the articular
  extremities when in place. The ribs are rather short, slightly curved,
  apparently hollow and intercentral in position. Although the vertebral
  centra are ossified, the elements of the cranium have a larval
  appearance. These consist of two parallel bony plates, which resemble
  the fronto-parietal bones of the frog; they are slightly separated
  from each other, but do not inclose a fontanelle. A wedge-shaped bone
  extends from the outside of the front of each of these, acuminate
  behind, and widening anteriorly in the position of a postfrontal bone.
  In front of the posterior border of each parietal, on its outer side,
  a bony enlargement arises which contracts outward and forward into a
  narrow element which curves forward beneath the postfrontal. These
  look like an anteriorly directed quadrate with articular bone, such
  as seen in the larvæ and some adults of existing batrachians. These
  determinations will require confirmation from additional material.
  In the meantime it is evident that the present specimen can not be
  referred to any of the other species herein described. The elements of
  the cranium are entirely smooth with no sign of sculpture, and in this
  respect the present species is unlike any of the other known from the
  Carboniferous."

The vertebræ are not so clearly marked as one is led to believe from
Cope's figure.

Measurements of the Type of Molgophis wheatleyi Cope.

                                         mm.
  Length of entire specimen              63
  Length of portion of skull preserved    9
  Posterior width of same                 8.5
  Length of a vertebra                    1.5
  Width of a vertebra                     1.5
  Length of a posterior rib               5
  Width of rib                            5

The species is dedicated to Charles M. Wheatley, of Phœnixville,
Pennsylvania, one of the original investigators of the Linton deposits. It
is a part of the Newberry Collection.

Additional material of this species is represented by specimens Nos. 7
and 8699 G of the American Museum of Natural History. They are both very
unsatisfactory. They consist of molds of the vertebral column, with in
one case an enlargement at one end which may represent the head, and if
such, the specimen probably represents a distinct species. The impression,
No. 7, contains molds of about 30 vertebræ which are very similar in
form to those exhibited by the type of the species. To the vertebræ
are articulated short, curved ribs of a slender nature. The vertebræ
themselves are short and somewhat constricted in the middle.

The other impression, 8699 G, contains impressions of about 20 vertebræ,
apparently immature, though one can not be entirely sure as to the
nature of the structures. They are covered over with a thin layer of
carbonaceous material which is impossible to remove satisfactorily. The
two specimens remind one of what Huxley has written in regard to the forms
of Microsauria (334) from Kilkenny, Ireland.

Measurements of Nos. 7 and 8699 G (Molgophis wheatleyi).

                                 mm.
  Length of No. 7                87
  Length of head mold            18
  Posterior width of head         6
  Length of vertebra              2
  Length of rib                   3
  Length of specimen No. 8699 G  53


=Genus ERPETOBRACHIUM Moodie, 1912.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 353, 1912.

Type: _Erpetobrachium mazonensis_ Moodie.

The generic characters are apparent in the greatly elongated fore limb,
in the exceptionally broad scapula, the long radius and ulna, which
slightly exceed the humerus in length, a character hitherto unknown among
Carboniferous Amphibia.


=Erpetobrachium mazonensis Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 353-354, pl. 2, fig. 2;
    pl. 8, fig. 3, 1912.

Type: Specimen No. 799 (222), Yale University Museum.

Horizon and locality: Mazon Creek shales, near Morris, Illinois.

The scapula of the present form is exceptional in its shape. It resembles
an asymmetrical pyramid, the anterior side of the lower edge of the bone
being contracted so that the anterior edge of the element is arcuate. Its
top is very thin and possibly terminated in a broad cartilage. The lower
end is thick and heavy and the articular surface is, apparently, well
formed, though somewhat obscured.

The element identified as a clavicle is lying on its edge and has the
proportions of the clavicle of _Mazonerpeton costatum_. The exterior
edge is somewhat rounded and small. A portion of another element which I
suppose to represent the coracoid lies alongside the humerus, although its
form is quite obscured. (Plate 3, fig. 3.)

The humerus has a remarkably well-formed head. In perfection of formation
it corresponds well with that of the higher reptiles. This surface can
even be divided into an anterior and a posterior articulation. The element
projects posteriorly for the distance of 1 mm. from the surface of the
shaft. The shaft immediately below the head is somewhat flattened and has
an ovoid section. Further on it becomes flattened, a part of which is
probably due to pressure during fossilization.

The elements of the forearm are both preserved and are approximately equal
in size. They are remarkable in that they exceed the humerus in length,
although they are not so heavy as that element. They are greatly elongate
and slender, with the middle of the shaft only moderately contracted. The
articular surfaces are well formed and both bones were hollow, as was
also, apparently, the humerus. The ulna may be represented by the most
posterior of the two elements, though the relations of the elements may
have been reversed (fig. 15, D).

The base of the left wing of an orthopterous insect possibly allied to
_Paolia gurleyi_ Scudder lies between the radius and ulna. The nodule also
contains impressions of plants, a portion of a frond of a _Neuropteris_
and the impression of one of the Cordaites. Lying next the radius is a
slender elongate element which may be a rib or a portion of a metacarpal.
If a rib, it indicates that the animal belongs among the Branchiosauria.
The fragment is only half as long as the radius and is entirely too
obscure to base any conclusions. The other characters of the specimen
point quite strongly to its microsaurian affinities.

The structure of the articular surfaces of the limb bones alone would
indicate the microsaurian relationship of _Erpetobrachium_. It may be
provisionally associated in the family Molgophidæ with such forms as
_Molgophis brevicostatus_ Cope, _Molgophis_ (_Pleuroptyx_) _clavatus_
Cope, and _Molgophis macrurus_ Cope from the Coal Measures of Linton, Ohio.

Measurements of the Type.

                           mm.
  Length of scapula        14
  Distal width              6
  Proximal diameter         3
  Length of clavicle (?)   24
  Length of humerus        25
  Length of ulna           24
  Proximal width            4
  Diameter of shaft         2
  Distal width              3
  Length of radius         25
  Proximal width            4
  Diameter of shaft         3
  Width of distal end       4


=Genus PLEUROPTYX Cope, 1875.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 370, pl. xlii, fig. 1; pl.
    xliv, fig. 2, 1875.

  Cope, Proc. Phila. Acad. Nat. Sci., p. 16, 1875.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909.

Type: _Pleuroptyx clavatus_ Cope.

The specimens on which the species of this genus repose do not exhibit
crania. The 5, probably 6, specimens which represent them offer various
views of the vertebral column, and in none is there any trace of ventral
or thoracic armature. Limbs can be ascribed to them with probability only.
The vertebræ are of moderate length, with well-developed zygapophyses, and
a short and not very elevated neural spine in the dorsal region, which
is not sculptured in any way. The generic character is seen in the ribs.
These are rather short and very stout and support an ala on the posterior
or convex border, which expands downwards, and then suddenly contracts to
the shaft. The extremity of the latter is broad and truncate, and includes
a medullary cavity, which is only partially fitted with cancellated tissue.


=Pleuroptyx clavatus Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 370, pl. xlii, fig. 1; pl.
    xliv, fig. 2, 1875.

  Cope, Proc. Phila. Acad. Nat. Sci., p. 16. 1875.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909.

Type: Specimen No. 8617 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The general appearance of the species of Pleuroptyx is that of the
Molgophis, so far as known, but nothing resembling the peculiar structure
of the ribs is seen in any other. There is no assurance that the genus is
distinct from Molgophis.

Parts of two individuals express the typical characters of this species,
while a third only differs in being considerably smaller. A fourth may
very probably be referred here, and another, bearing several elements of a
leg, should be most likely associated with the last mentioned.

The ribs are considerably narrowed near the head, and appear to possess
a low tubercular process some distance below it. The shaft is curved
throughout; the laminar expansion is quite thin; while the distal end is
expanded and concave, perhaps for the attachment of cartilage, although no
trace of this remains on the shale. The neural spines have short bases,
oblique anterior and nearly straight posterior borders, with obtuse
extremity. I perceive no essential difference in the smaller specimen,
which is one-third less than the types.

The limb is appropriate in its proportions to the present species, and may
be described in this place. The first segment is one-third longer than
the second, and has a transversely expanded head. The shaft is stout, the
distal extremity not expanded and concave. The second segment is stout,
more expanded proximally than distally, the proximal end truncate and
slightly concave. A bone, much displaced, lies near it, and is probably
ulna or radius; it is as stout as the first, the end not expanded. Of
metatarsals there are 2, three-fifths the length of the second bone of the
leg, and of phalanges 2, of 2 digits each. The proximal are three-fourths
the length of the metatarsals, and indicate elongate toes. The obverse of
the specimen is preserved, and contains no additional toes or phalanges.

[Illustration: Fig. 33.--Forelimb of a member of the Molgophidæ, possibly
Pleuroptyx clavatus Cope. × 0.75.]

Measurements of the Type of Pleuroptyx clavatus Cope.

                                     mm.
  Length of vertebral centrum        14
  Depth of a vertebral centrum        9
  Depth of entire vertebra           22
  Length of neural spine              8
  Height of a neural spine            6
  Length of a rib on the curve       42
  Width of a rib at ala               9
  Width of a rib at extremity         5
  Length of first segment of leg     38
  Length of second segment of leg    24
  Length of metapodial bone          10
  Length of first phalanx             7

Hitherto only two portions of the dorsal series and a left limb have been
assigned to this species. The present specimen (No. 4479, U. S. Nat. Mus.)
thus proves of interest in determining that the creature was long-tailed,
like _Œstocephalus_, _Ptyonius_, and _Phlegethontia_, but unlike the first
two genera the neural and hæmal spines are not elongate nor marked with
radiating lines. The neural spines are indistinct and if developed at all
were very low and short.

The centra are short, cylindrical, and thick. They gradually decrease
in size to where they are lost, since the portion preserved does not
represent the entire length of the tail. There may have been 15 more
vertebræ distally and 5 more proximally, thus making about 75 caudal
vertebræ, as Woodward (630) has determined obtains in _Ceraterpeton
galvani_ Huxley.

The ribs are continuous throughout the length of the tail preserved and
have precisely the same structure as is found in the dorsal region with
the possible exception that the posterior alar expansion is not so well
developed in the caudal ribs. The ribs are decidedly fan-shaped and
articulate by a single head with a short transverse process. They are
distinctly curved like all microsaurian ribs.

Measurements of Specimen of Pleuroptyx clavatus Cope.

(No. 4509, U. S. National Museum, Linton, Ohio, Coal Measures.)

                                       mm.
  Length of tail as preserved         105
  Length of anterior vertebra           1.5
  Diameter of anterior vertebra         1
  Length of rib                         5
  Width of rib                          1

The above-described specimen represents what I suppose to be the posterior
part of the body of _Pleuroptyx clavatus_ Cope. The characters of the ribs
and vertebræ are the same. The fragment is interesting, since it gives
an insight into the form of the body, which was slender, conforming thus
to other long-tailed microsaurs. Length of specimen, 65 mm.; width of
specimen, 30 mm.

There is still a third example of this species among the collections
belonging to the National Museum (No. 4484). The specimen includes a badly
crushed posterior portion of a skull and a series of about 16 crushed
vertebræ, with several pairs of ribs and ventral scutes.

Very little can be said of the skull save that the maxilla of the right
side was long and bore from 15 to 20 teeth, of which 9 are preserved more
or less completely. The mandible is likewise crushed and one can not
determine its elements. Portions of 2 or 3 teeth are preserved. The form
of the mandible is long and slender.

The ventral scutes are of the pectoral region. They are long, slender, and
thread-like. They are not closely packed, but I count 12 in a distance of
a millimeter.

So far as can be determined the vertebræ are the same as has been
described for other specimens. They are short and heavy. The ribs show,
for the most part, the same characters as the type specimen.

Measurements of Third Specimen (No. 4484, U. S. Nat. Mus.).

                                            mm.
  Length of specimen                        60
  Length of preserved portion of skull      15
  Length of tooth                           25
  Posterior width of mandible                3
  Length of anterior Vertebra                2
  Length of rib                              4
  Width of rib                               1


=Genus PHLEGETHONTIA Cope, 1871.=

  Cope, Proc. Am. Phil. Soc., p. 177, 1871.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 366, 1875.

Type: _Phlegethontia linearis_ Cope.

This is one of the most interesting genera of the present series. It
rests chiefly on a single specimen of one species, which is not perfect,
but which displays the following characters: Head elongate-triangular;
body and tail extremely elongate, the dorsal vertebræ without ribs, and
the caudals without dilated spines; no ventral armature nor limbs. As a
great portion of the length is presented, and no ventral rods or scales
are visible, and as this character is confirmed by a second specimen, it
probably belongs to the genus. The pectoral shields are also wanting in
the specimen, but as there is a considerable vacuity behind the skull of
the specimen, it may be that these were lost with other parts. Chevron
bones are not observable on the caudal vertebræ. This form is a true
amphibian snake.


=Phlegethontia linearis Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 367, pl. xliii, fig. 2, 1875.

Type: Specimen in the American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

In the only specimen the dorsal vertebræ are much involved anteriorly,
so that the length is not readily ascertained. There is an outline of
a triangular object which may represent the skull of this specimen,
although it is so far removed from the vertebræ that there is some doubt
as to whether it belongs with the vertebræ or not. Indeed, there is even
doubt whether it is a skull. The vertebræ have longitudinal diapophysial
keels, and have a zigzag interlocking of neural arches. The latter are
distinctly turned outward. The vertebræ are very numerous, and the tail
very attenuated. The number preserved is about 60. The total length of
the coils unwound is about 295 mm., or 11 coils in 8 lines; but there are
interruptions not measured and confusions not unraveled.

This is the most elongate and slender of all the species of the
Carboniferous Amphibia. The vertebræ are apparently ribless and there are
no evidences of limbs or pectoral plates. It may be said that the body
consists entirely of skull and vertebræ.

Measurements of the Type of Phlegethontia linearis Cope.

  Entire length of skull (?)                  18    mm.
  Width of same                                8    mm.
  Length of vertebral column as preserved    295    mm.
  Length of single vertebra                    2.50 mm.
  Height of vertebra                           1.50 mm.
  Estimated length of body                    15    in.

No. 8370 G, American Museum of Natural History, shows a few vertebræ.


=Phlegethontia serpens Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 367, pl. 32, fig. 2, 1875.

Type: Specimen No. 1102 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

This amphibian is much larger than the last, approaching nearly in its
dimensions the _Molgophis macrurus_. It is represented by a series of 22
vertebræ, which, like those of _Phlegethontia linearis_, are devoid of
ribs, abdominal armature, dilated neural spines, etc. The series when
complete must have been very long, as there is little difference in size
between the first and the last of the 22. They are marginate fore and
aft, and much contracted medially, owing to the transverse expanse of
the diapophyses. There may be, indeed, a diapophysial element beneath
these, but, if so, the two are indistinguishable. They are connected by
longitudinal impressions, indicating the existence of the tendinous bands
in the longitudinal muscles seen in _Amphiuma_, or the osseous spicules
seen in the same situation in birds. The neural spines, as indicated by
their narrow bases, occupy the length of the neural arch, and remind one
of _Amphiuma_. Width of one of the vertebræ, 3 lines.



CHAPTER XXI.

THE MICROSAURIAN FAMILY SAUROPLEURIDÆ, FROM THE COAL MEASURES OF OHIO.


=Family SAUROPLEURIDÆ Hay, 1902.=

  Hay, Bull. U. S. Geol. Surv., No. 179, p. 419, 1902.

The present family is an association of related forms due to similar
structure of vertebræ, ribs, ventral scutellation, and limbs. There is no
character in the skull which would indicate a separation of the genera
here included, at least in the light of present knowledge.

The family may be characterized as: Subaquatic or terrestrial vertebrates
with a typically amphibian development of the ventral armature; ribs
intercentral, as in all members of the order; skull elongate and slender
or broad and obtuse; cranial and dermal elements of the pectoral girdle
sculptured; lateral-line canals indicated in one genus, Saurerpeton; limbs
well developed, with well-developed digits and ungual phalanges claw-like;
body usually slender, broad in Saurerpeton; the ribs broad and heavy; the
vertebræ relatively stout; ventral armature highly developed, reaching
the height of specialization among the Microsauria; scutellæ consisting
of rods, plates, or stout bristles. The family is represented by 5
genera: _Sauropleura_, _Saurerpeton_, _Ctenerpeton_, _Leptophractus_, and
_Eurythorax_, the association of the last two genera being provisional.
The genera may be distinguished as follows:

    I. Pectoral elements sculptured, clavicles triangular, interclavicle
         diamond-shaped, ventral scutellæ rods, arranged _en chevron_
         with anterior angle                                  _Sauropleura_

   II. Pectoral elements slightly sculptured, cranium broad, obtuse and
         sculptured, ventral armature broad imbricated plates extending
         on to the throat                                     _Saurerpeton_

  III. Limbs, skull, arches and dorsal vertebræ unknown, caudal
         vertebræ with fan-shaped neural and hæmal spines which may
         indicate relationship with _Ptyonius_ and _Œstocephalus_,
         but in those genera the ventral armature is weakly
         developed; ventral scutellæ curved rod-like plates arranged
         _en chevron_ with anterior angle, marked in abdominal
         region by distinct rounded pits                      _Ctenerpeton_

   IV. Known only from fragments of the skull, teeth large and fluted;
         association in family provisional                  _Leptophractus_

    V. Known only from a single interclavicle of peculiar form which
         resembles that of _Saurerpeton_; association in the
         family provisional                                    _Eurythorax_

The members of this family are confined to the deposits of the Coal
Measures at Linton, Ohio. _Ctenerpeton_, and possibly _Sauropleura_, were
highly developed swimmers, but the strength of the limbs as exhibited,
especially by Sauropleura and Saurerpeton, indicates that they had not
entirely forsaken the land.


=Genus SAUROPLEURA Cope, 1868.=

  Newberry, Proc. Phila. Acad. Nat. Sci., VIII, p. 98, 1856 (Pygopterus
    scutellatus).

  Cope, Trans. Am. Phil. Soc., p. 22, 1869.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 402, 1875.

  Hay, Bull. U. S. Geol. Surv., No. 179, p. 419, 1902.

Type: _Sauropleura scutellata_ Newberry.

Vertebra and ribs well developed; limbs 4, rather large; 5 digits in the
forefoot; carpus cartilaginous. Ventral armature of closely arranged
rhomboidal scuta, arranged in lines, which are closely placed in chevrons,
with the angle anterior.

In none of the species of this genus have the usual 3 thoracic shields
(clavicles and interclavicles) been observed. The abdominal scutæ, on the
other hand, are much like those of _Saurerpeton_, being, however, smaller.

The species formerly described by Cope in the genus _Colosteus_ are
included in _Sauropleura_, where they find their closest allies.

There are 7 species belonging in this genus: _Sauropleura digitata_
Cope, _S. newberryi_ Cope, _S. foveata_ Cope (_Colosteus_), _S.
scutellata_ Newberry (_Colosteus_) (type of genus), _S. pauciradiata_
Cope (_Colosteus_), _S. longidentata_ Moodie, _S. enchodus_ Cope
(_Anisodexis_). The species described by Cope as _Sauropleura latithorax_
is regarded as belonging to a distinct genus, _Saurerpeton_.


=Sauropleura scutellata Newberry.=

  Newberry, Proc. Phila. Acad. Nat. Sci., p. 98, 1856 (_Pygopterus
    scutellatus_).

  Cope, Proc. Phila. Acad. Nat. Sci., p. 215, 1868.

  Cope, Trans. Am. Phil. Soc., p. 22, 1869.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 402, 1875.

Type: Specimen No. 8669 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures. (Plate 14, fig. 3.)

This species was first described by Newberry as a fish belonging to the
genus _Pygopterus_. Cope later placed it under the genus _Colosteus_
and clearly showed its amphibian characters. The genus _Colosteus_ was,
however, based on a misconception. Cope in 1897 and Hay (317) referred
the species to _Sauropleura_, where it is retained. The species is
represented by a single individual preserved on a block of coal from
Linton, and is also indicated by an interclavicle and its obverse; this
element is of larger size than that of the type and was referred by Cope
to _Colosteus pauciradiatus_. The characters of the plate are, however, so
identical with those of the interclavicle in the type specimen that it is
unhesitatingly referred to the present form.

The type specimen consists of the supero-lateral view of a crushed cranium
with the anterior part of the body, exhibiting the interclavicle and the
ventral scutellation. No limbs have been observed in this species. The
mandibles are crushed across the cranium in such a way as to obscure its
structure. The boundary of the left orbit is doubtfully determined as
being a little back of the median line of the skull. There are small teeth
present on the mandibles, but their number can not be determined. The
cranial elements are sculptured with radiating grooves and ridges, but
these are weakly developed. The snout is broad and but little narrower
than the base of the skull. (Plate 21, fig. 5.)

The interclavicle, somewhat displaced, is the only element of the
pectoral girdle preserved. It is peculiar in the possession of a backward
extension which shows a beveled edge. The plate is ornamented by radiating
grooves and ridges which are strongly developed. The larger specimen of
an interclavicle shows the same characters as the one described, and it
differs only in being about twice as large. There are no traces of limbs.

The ventral armature of the body is rather weak as compared to that of
_Sauropleura pauciradiatus_, but it is still composed of closely packed
scutes arranged _en chevron_. The character of the ventral armature and
the sculpturing of the interclavicle are taken as the principal specific
characters. From the other species of the genus the present form differs
in its more slender elements of the ventral armor and in the form of the
skull. The ribs are not clearly defined.

Measurements.

                                     mm.
  Median length of skull             70
  Posterior width of skull           40
  Anterior width of skull            20
  Length of jaw                      50
  Anterior width of jaw               7
  Posterior width of jaw             12
  Length of mandibular tooth          1.5
  Length of entire specimen         150
  Width across belly, maximum        47
  Length of interclavicle            27
  Width of interclavicle             13
  Width across posterior extension    4


=Sauropleura digitata Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 216, 1868.

  Cope, Trans. Am. Phil. Soc., XIV, p. 15, 1869.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 403, pl. xxxvii, fig. 1, 1875.

Type: Specimen No. 8004 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures. (Plate 20, fig. 4.)

This species is represented by a single individual which is quite distinct
from other members of the genus. The specimen has been spread over a
surface of the coal, and exhibits ventral armature, dorsal region with
ribs, and anterior and posterior limbs. Skull and caudal region not
present.

The ventral armature is arranged in parallel lines directed obliquely
forwards and continuous on the median line, forming there a chevron. The
individual elements are oat-shaped, and acuminate at both ends. They are
moderately imbricate in an antero-posterior section. On the pectoral
region between the fore limbs the series of scutellæ assume different
directions, forming chevrons directed backwards, and forming with those of
the belly a complete =X=.

The humerus, ulna, and radius are rather stout, and of a size relative
to the body, as in common types of existing lizards; the ulna and radius
separate. The carpus is cartilaginous; the digits are 5 well-developed
fingers having phalanges in the following numbers, commencing on the
inside: 3, 4, 5, 6, 5. The last phalanx of the second is obscured, and it
is not positive that the number is as given; it is more probable that it
was 4 than 3. The outer toe was more slender than the others; the distal
phalanges of all the toes are stout, as in modern Caudata.

The ribs are long and curved as in reptiles, and judging by their
distances the vertebræ are short; the latter are not well-defined, but
there is no indication of prominent spines of any kind. The pelvic bones
and portions of the hind limbs are present, but so obscured and confused
as not to be easily made out. Enough remains to show that the hind limbs
were longer than the fore. Thirteen ribs on one side and twelve on the
other are preserved, with short ribs in the sacral region. The specimen
is very indistinct and it is difficult for one to be sure of all the
characters described by Cope.

Measurements of the Type of Sauropleura digitata Cope.

                                     mm.
  Length of specimen                 115
  Greatest width                      80
  Diameter of ventral scute             .75
  Length of rib                       15
  Width of rib                         1
  Length of humerus                   20
  Length of radius                    10
  Length of ulna                       9
  Length of metacarpal                 4
  Length of fourth digit of hand      22
  Length of interclavicle             20
  Width of interclavicle              11

The interclavicle is diamond-Shaped, with surface punctate and edges
radiately grooved at a distance of 1.5 mm. from the edge. The hand on the
right side of the specimen contains 3, 3, 3, 6, 3 phalanges. The vertebræ
are all imperfectly preserved.

Other specimens of this species are 2567 (48), 8376 G, 8704 G, American
Museum of Natural History. Coal Measures of Linton, Ohio. Collected by Dr.
J. S. Newberry.


=Sauropleura newberryi Cope.=

  Cope, Geol. Surv. Ohio, II, pt. II, p. 404, pl. xxxvii, figs. 2 and 3;
    pl. xli, fig. 5, 1875.

Type: Specimen No. 8612 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The type specimen of the species exhibits a portion of the posterior
part of the skull, a considerable part of the body, with the fore limbs
and abdominal scutellæ. No vertebræ can be definitely discovered and
the ribs are not distinctly visible. The cranial fragment is the upper
surface of the tabulare and adjacent elements, and a broad band of the
posterior parts of these is seen to be smooth, and is preceded by a
slightly roughened surface. The abdominal scutæ are diamond-shaped, and
are thin and light, not massive, as in _S. scutellata_, and are sometimes
marked with a median longitudinal keel. The fore limb is large, especially
the humerus, which is much dilated distally, and has a strong crest
on the outer side from near the proximal end. The ulna and radius are
much shorter, and more dilated proximally than distally; they are well
separated. No phalanges are preserved.

The species is represented by other specimens, all of which are
unsatisfactory in determining the structure of the form. A skull,
apparently complete, is crushed out flat, so that little can be said of
structure. The teeth are rather long, straight, acute, and striate at the
base. The orbits are long and narrowed in front.

Measurements of Sauropleura newberryi Cope.

(No. 8612 G, and two unnumbered specimens, American Museum of Natural
History.)

                                     mm.
  Length of humerus                  35
  Proximal width of humerus           8
  Distal width of humerus            14
  Length of ulna                     19
  Proximal width of ulna              8
  Posterior width of skull           67
  Width at anterior angle of orbits  40
  Interorbital space                 13
  Width of orbit                     13
  Length of orbit                    27
  Length of a maxillary tooth         4
  Diameter of same at base            2


=Sauropleura pauciradiata Cope.=

  Cope, Trans. Am. Phil. Soc., XV, p. 275, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 408, pl. xl, figs. 1-2, 1875.

Type: Specimen No. 8671 G, and obverse, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The species was founded on a median and a lateral plate of 2 individuals.
The clavicle is here associated with _S. scutellata_ and the interclavicle
thus remains as the type specimen. There are other remains associated by
Cope with _S. scutellata_ which are here shown to have closer affinities
with the _S. pauciradiata_.

The clavicle is a right-angled triangle, the inner and thin edge concave
posteriorly, the posterior convex. The ridges and grooves are well
developed on the specimen. The visceral side of the element is smooth.

Cope referred to _S. scutellata_ the larger part of an individual with
strongly developed ventral scutellation. This he figured on plate XXXVI,
fig. 2 (123). Even a cursory glance will, however, suffice to show that
the sculpturing of the clavicle just described and that exhibited by the
specimen there figured are identical. Closer examination shows important
differences between the species, the principal distinctions being the
strongly developed ventral scutellæ in _Sauropleura scutellata_, the
difference in form and sculpture of the interclavicles, and the posterior
extension of the interclavicle in _S. scutellata_ which is wanting in _S.
pauciradiata_. The sculpturing of the interclavicle in the form figured
by Cope as _S. scutellata_, just referred to, is identical with the
sculpture of the clavicles, as would be expected. The ridges on all of the
pectoral elements of _S. pauciradiata_ are strong and are rather few in
number, while in _S. scutellata_ the sculpturing is more in the form of
interrupted grooves.

The specimen (plate 14, fig. 3) exhibits the great part of the body with
one fore limb. The skull is wanting. The belly was very broad and strongly
protected by broad, long scutes arranged _en chevron_. The scutes are
close together and form a compact ventral armor for the animal. The fore
limb is very weak. The humerus is represented by its distal end only. The
radius and ulna are very short and weakly developed in comparison to the
size of the animal. The limbs could not have supported the animal on land
and served, probably, merely as organs of equilibration, for the animal
was undoubtedly aquatic. The fingers are not all preserved and there is no
carpus.

Numerous other remains formerly associated with _S. scutellata_ are here
referred to _S. pauciradiata_, on account of the strongly developed
ventral armor, which is different from that of the type of _S.
scutellata_. The remains do not, however, add to our knowledge of the
anatomy of the forms, as they are very fragmentary.

Two skulls are provisionally associated with this species. One of these
skulls is figured by Cope (123) on plate XXXIII, fig. 1. It is there
referred to _S. scutellata_. That it can not, however, be referred to
that species is manifest when the teeth are observed. In the type of
_S. scutellata_ the teeth are very small, sharp denticles, while in the
skull under discussion the teeth are well developed and their bases are
longitudinally grooved. The teeth are elongate in the anterior part of
the skull and are shorter posteriorly. They are, however, all strong. The
skull is acuminate and the orbit is located about midway of its length.
The jaw is slightly longer than the cranium. The structure of the cranium
can not be determined in either skull, and in one only the position of the
orbits and the teeth.

[Illustration: Fig. 34.

  A. Interclavicle of Sauropleura pauciradiata Cope. × 1. (After Cope.)

  B. Left clavicle of Sauropleura pauciradiata Cope. × 1. (After Cope.)

]

Measurements of the Specimens of Sauropleura pauciradiata Cope.

                                      mm.
  Length of clavicle, left             43
  Width of clavicle                    25
  Space between ridges                  2

_Large specimen No. 8657 G and obverse (13) described us Colosteus
scutellatus Newb._

                                      mm.
  Length of specimen, as preserved    117
  Width of specimen, maximum           61
  Length of forearm                     9
  Length of hand                       10
  Length of metacarpus                  5
  Length of clavicle                    4
  Width of clavicle                    18
  Length of interclavicle              40
  Width of interclavicle               23
  Width of a ventral scute              1.5
  Length of scute from angle to end    35

_Skull No. 8666 C, plate xxiii, fig. 1 (Cope, 123), Colosteus scutellatus._

                                      mm.
  Length of skull, as preserved        65
  Width of skull                       40
  Diameter of orbit                     6
  Length of mandible                    7
  Width of mandible, maximum           10
  Length of longest tooth               5
  Width of tooth at base                1.5

_Skull Nos. 8602 G and 8608 G._

                                      mm.
  Length of skull, as preserved        50
  Width of skull                       60
  Diameter of orbit                    15
  Length of mandibular tooth            4.5

Other specimens associated with this species: Nos. 8668 G, 86746, 85540,
8661 G. All specimens in the American Museum and all from Linton, Ohio.


Scutes of Sauropleura.

There are found associated with the remains of the genus _Sauropleura_
a number of heavy scutes or scales. There are three of them on the same
block as the specimen of _S. longidentata_ and are provisionally referred
to the genus. There are a number of scutes preserved separately, but they
agree in their characters with those discovered on the specimens. The
scutes are elongate and usually acuminate at one end and having a broad
base at the other. The acuminate end is slightly bent to one side so as
to present the appearance of a hook. Others are shield-shaped and are
quite large, while the majority of the hook-shaped ones are small. The
shield-shaped elements have a rounded boss near the center of the plate
and the edges are imbricated. Their nature and their proper location on
the animal are a puzzle. They may not belong to the genus, but have been
noticed with the remains of at least 3 species.

Measurements (in Millimeters) of Scutes Associated with the Specimens of
Sauropleura.

  No. 4513 U. S. National Museum:
      Length                               27
      Width, maximum                       14
      Width, minimum                        3

  Scutes associated with the specimen of _Sauropleura longidentata_:
      Width across base                     3
      Width across tip                      1

Additional specimens are: Nos. 3, 8673 G and 8470 G, American Museum of
Natural History.


=Sauropleura longidentata Moodie.=

  Moodie, Jour. Geol., 17, No. I, pp. 74-76, figs. 18, 19, 1909.

Type: Specimen No. 8619 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

[Illustration: MOODIE                                           PLATE 22

  1. Type of _Leptophractus lineolatus_ Cope, from the Coal Measures
       of Linton, Ohio. Portions of maxilla and mandible of left side
       with teeth. × 1. Original in American Museum of Natural History.

  2. Type of _Proterpeton gurleyi_ Moodie, from the Coal Measures
       of Illinois, near Danville. Cervical of an otherwise unknown
       vertebrate. Neural spine to the right. Original in Walker Museum,
       University of Chicago × 2.

  3. Amphibian phalanx from the Coal Measures near Breeze, Illinois,
       of an unknown species. The probable form of the element is
       represented. × 3.

  4. Large rib of a stereospondylous stegocephalan otherwise unknown.
       The rib may represent a species of _Macrerpeton_ or may even
       belong with _Macrerpeton deani_ Moodie, but exact identification
       will have to wait for future discoveries. From the Coal Measures
       of Linton, Ohio. Original in U. S. National Museum. × 1.

  5. Type of Cope's species _Tuditanus mordax_ referred by him to the
       cranium, on account of the sculpturing of the elements. We
       now know the specimen to be portions of the interclavicle and
       clavicles of _Diceratosaurus punctolineatus_, as Cope suggested
       they might be. Original in American Museum of Natural History. ×
       1.

  6. Skull of _Baphetes planiceps_ Owen from the Coal Measures of Nova
       Scotia. × 0.45. Original in the British Museum. South Kensington.
       After Owen.

]

This species may be distinguished from other members of the genus by the
large size and shape of the cranium (462) and the broad mandible (plate
16, figs. 2, 3) with its very long teeth. The skull of _Sauropleura
digitata_ Cope is not known, but the body of that animal as preserved
represents far too small a form for the skull to be referred to that
species. The skull is fully half as long as the dorsal region of
_S. digitata_ Cope, so that an association of the remains would be
incongruous. It differs from the skull of _S. scutellata_ Newberry in
size and proportions. The skull of _S. scutellata_ is narrow, while in
_S. longidentata_ it is quite broad. The teeth of the latter are also
characteristic of the species, since in all other known species of this
genus in which the skull is preserved the large anterior tooth is wanting.

The bones of the skull show the coarse sculpturing of the larger species
of Microsauria. It consists more of radiating grooves than of pits. The
skull, as restored (462), is broadly ovate, with the posterior border
truncate. The muzzle is broad and the nostrils are, apparently, located
near the anterior margin.

The posterior border of the orbits lies near the median transverse line of
the skull. They are circular and are removed some distance from the margin
of the cranium. Only the frontal and parietal can be determined with
certainty.

The mandible is heavy and is provided with pleurodont, heterodont teeth.
Near the anterior end of the mandible there is a very long fang-like
tooth, longitudinally striated and slightly recurved, which arises from
a broad base and attains to considerable prominence. The other teeth are
smaller, though the next succeeding one is still of considerable size.
All of the teeth preserved are longitudinally striated, but only the two
anterior ones are recurved to any extent.

Measurements of the Type.

                                                   mm.
  Length of the skull in median line                75
  Width of skull at posterior border, estimated     80
  Width of skull across orbits                      60
  Width of orbit                                    10.6
  Length of orbit                                   12
  Interorbital space                                16
  Length of jaw, as preserved                       48
  Width of jaw, maximum                             16
  Width of jaw, minimum                              5
  Length of largest tooth                           11
  Width of longest tooth at base                     4.5
  Length of shortest tooth                           3
  Width of shortest tooth at base                    1


=Sauropleura foveata Cope.=

  Cope, Trans. Am. Phil. Soc., XIV, p. 24, 1869.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 406, pl. xxxvi, fig. I, 1875.

Type: Specimen No. 8676 G and obverse No. 8675 G, American Museum of
Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

This species is represented by an interclavicle and its impression, which
show a beautiful sculpturing entirely distinct from that of the other
species of this genus. In size it is intermediate between the largest of
the interclavicles of _S. scutellata_ and _S. pauciradiata_. The pattern
of the sculpturing is, however, its main distinction. The plate is finely
pitted and there are few evidences of grooves. Near the posterior border
of the plate the pits become somewhat defined by ridges which take on a
radiating pattern with the center of the plate as the center. The beveled
margins are rugose, except at the edges.

Measurements of the Type Specimen of Sauropleura foveata Cope.

                                      mm.
  Median length of interclavicle      43
  Width of interclavicle, maximum     23


=Sauropleura enchodus Cope.=

  Cope, Proc. Am. Phil. Soc., p. 406, 1885 (_Anisodexis_).

Type: Specimen No. (51) 2558, American Museum of Natural History, Newberry
Collection.

Horizon and locality: Discovered by Sam Huston at the Linton, Ohio, Coal
Measures.

An examination of the type specimen (plate 16, fig. 4) of this form
resulted in no new facts. The reference of the species to the Permian
genus _Anisodexis_ by Cope is probably incorrect. Our knowledge of the
two known species of this genus is not sufficient to separate them, but
for the sake of convenience the Linton species is placed in the genus
_Sauropleura_. It is located here principally on account of the form and
structure of the teeth. Cope's original description is given below:

  "The generic characters are apparent in the very unequally sized
  teeth with round section. The portion upon which the species is
  based is a part of the right ramus of the mandible, which is in the
  specimen viewed from the inner side. The jaw is obliquely and smoothly
  truncated from below, for the symphysis and surface of the bone is
  smooth. There is a very large tooth near the extremity of the dentary
  bone. Behind it is an interval equal to three times the diameter of
  its base, which is followed by a tooth of about one-third the length
  of the first tooth. Posterior to this one are two teeth of the same
  size as the second, all being separated from each other by about a
  tooth's diameter. These are followed by three subequal teeth of about
  two-thirds the length of the first tooth, and separated by about their
  own diameter from each other. They are all perfectly straight, very
  acute, and without the trace of a cutting-edge. The inflection-grooves
  extend to or a little beyond the middle of the length."

The present species is smaller than the type of _Anisodexis imbrecarius_
from the Texas Permian, to which genus Cope originally referred the
present species, and the apices of the teeth do not display the opposite
cutting-edges seen in the Texas form.

Measurements of the Type Specimen.

                                        mm.
  Length of jaw, including 7 teeth      31
  Depth of ramus at second tooth        10
  Length of first tooth                 10.5
  Length of third tooth                  3.5
  Length of sixth tooth                  7.5


Skin of Sauropleura Sp.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, p. 355, pl. lx, fig. 1, 1909.

The present specimen is interesting on account of the presence of what I
take to be a portion of the skin, which is preserved as a smooth mold over
the ribs and ventral scutellæ. The skin was undoubtedly that of the back,
since the creature is preserved on its belly, and is interesting in not
showing the slightest trace of scales or other hard plates. The ventral
scutellæ are characteristic of the species of the genus _Sauropleura_.
With one species of this genus, _Sauropleura scutellata_ Newberry, the
writer has found associated scutes of some size, and the same fact has
been noted by Cope.


=Genus SAURERPETON Moodie, 1909.=

  Moodie, Jour. Geol., XVII, No. 1, p. 80, fig. 23, 1909.

Type: _Saurerpeton latithorax_ Cope.

This generic name is erected for the reception of a single species
described by Cope in 1897. The name is made necessary by the wide
divergence of the characters exhibited by the present species from those
of the species of the genus (_Sauropleura_) to which Cope (176) referred
this species. The form is not a member of the genus _Sauropleura_, for
reasons given below.

The species of the genus _Sauropleura_ have a lanceolate head with
homodont dentition or nearly so. The orbits are located well back in the
skull. The form of the body is elongate and slender and the limbs where
known are long and attenuated. The ventral scutellation consists of
oat-shaped scutes arranged in a chevron series. The form here described
as _Saurerpeton latithorax_ Cope has nearly the opposite of all of these
characters, and it is incongruous to locate the form under the former
genus. The skull of _Saurerpeton latithorax_ Cope is broad and heavy.
The teeth are heterodont. The body is broad and stout and the limbs are
of unusually strong proportions. The character of the ventral armature
is also of a very different type. In _Saurerpeton_ it consists of very
broad imbricating scutes which form a single piece across the abdomen and
are angulated to form the chevron pattern which is so common among the
Stegocephalia.


=Saurerpeton latithorax Cope.=

  Cope, Proc. Am. Phil. Soc., XXXVI, p. 86, pl. iii, fig. 4, 1897.

  Moodie, Jour. Geol., XVII, No. 1, p. 80, fig. 23, 1909.

Type: Specimen No. 4471, U. S. National Museum.

Horizon and locality: Linton, Ohio, Coal Measures. Collected by R. D.
Lacoe.

This species is indicated by remains of the anterior half of a large
amphibian (plate 17) preserved on a block of bituminous coal from the
Linton mine. The form is unusual in the proportions of the head and the
width of the thoracic region. In these characters it stands alone among
the Amphibia from this locality, where the forms are for the most part of
rather slender build and tapering, pointed head.

The skull is represented in a fairly complete condition and shows the
usual stegocephalian arrangement of the skull elements, as well as the
sculpturing of the bones, which is similar to that found in other members
of the Microsauria. The skull is broadly rounded, with the posterior
border incised, the broad tympanic notches thus rendering the shape of the
skull somewhat like that of the branchiosaurs. The orbits are broad ovals
and lie well forward in the skull. They are separated by a space which is
greater than the greatest diameter of the orbit. The pineal foramen lies
well back and is clearly indicated as a circular opening which lies in the
median suture in the posterior half of the parietals. The nostrils seem to
be elongate and have an oblique position, as is represented in the diagram
(fig. 35), but this character is not ascertained definitely.

The borders of the premaxillæ and the anterior suture of the nasal can
not be determined, though they may have had some such arrangement as
suggested. The nasal is represented, so far as is determinable, by an
oblong element lying between the frontal and the anterior border of the
skull. The f rentals are very large and form a portion of the inner border
of the orbit. The parietal is probably the largest bone in the cranium
and together the two elements form a large quadrangular space in the
posterior half of the skull. They inclose the circular pineal foramen.
The postparietal is a small element lying on the posterior border of the
skull and with the tabulare and a part of the supratemporal forms the
projection. The prefrontal is probably a small element, especially if
the lacrimal is present. There seems to be an indication of a suture
separating the lacrimal from the prefrontal, but this character is not
assured. The boundaries of the maxillæ are clear anteriorly. They indicate
that this element was elongate, as is usual, and impressions of teeth
borne on the mandible would indicate the probability that the teeth were
heterodont. In the premaxillary region there is a long, strong tooth
preserved, and on the maxillary near the posterior extremity of this bone
there are impressions of teeth which are no more than one-fourth as large
as the premaxillary one. The borders of the jugal can not be ascertained,
since the skull is injured on both sides in this region. Likewise the
quadratojugal is conjectural. The boundaries of the postfrontal and
the postorbital are clearly ascertained. They together form the entire
posterior border of the orbit and send prolongations along the lateral
borders of these openings. They are both acuminate posteriorly and these
points are inclosed by the tabulare and supratemporal for the postfrontal
and by the squamosal and prosquamosal space for the postorbital. The
boundaries of the tabulare show this element to be quite large and
extending forward into an acumination which is inclosed by the parietal
and the postfrontal. The sutures bounding the squamosal have been obscured
by injury in removing the specimen and are indeterminable.

[Illustration: Fig. 35.--Outline drawing of the skull and skeleton, as
preserved, of _Saurerpeton latithorax_ (Cope), from the Linton, Ohio, Coal
Measures. Original in U. S. National Museum. × 0.75.

  Skull: _fr_, frontal; _j_, jugal; _mx_, maxilla; _n_, nasal; _no_,
       nostril; _or_, orbit; _par_, parietal; _pof_, postfrontal;
       _po_, postorbital; _pp_, postparietal; _pf_, prefrontal;
       _pmx_, premaxilla; _qj_, quadratojugal; _m_, mandible; _spa_,
       supraorbital lateral-line canal; _spt_, supratemporal; _sq_,
       squamosal; _tab_, tabulare; _y_, pineal foramen.

  Skeleton: _cl_, clavicle: _c_, carpus; _rb_, ribs; _h_, humerus; _ic_,
       interclavicle; _met_, metacarpals; _psc_, pectoral scutellæ; _r_,
       radius; _vs_, ventral scutellæ; _u_, ulna.

]

The vertebral column is represented by a ridge showing along the median
plane of the specimen. Its characters can not be ascertained. There are a
few evidences of ribs. They represent long, slender, non-alate elements,
their mode of articulation with the vertebræ being obscured by the
plate-like ventral armature which covered the abdomen of the animal.

The pectoral girdle is represented by the remains of three elements which
are interpreted as being the interclavicle and the two clavicles. The
interclavicle is broad and is rounded posteriorly. There is no evidence
of the usual acumination posteriorly. The element is nearly as wide as
long. There is a prominent longitudinal keel on the ventral surface of
the interclavicle and radiating lines which may indicate the courses of
blood-vessels or nerves or may be the ornamentations of the element,
probably the latter. The clavicle has the usual microsaurian form. It has
three points and is truncate exteriorly. It is ornamented with radiating
grooves of a shallow and not strongly pronounced character. There is no
evidence of the coarse sculpture of the later forms. If the scapula is
represented it is merely by an indeterminate fragment insufficient for
description.

The pectoral limbs are preserved nearly entire. The left fore limb lacks
only a few phalangeal bones, and these were preserved with the remainder
of the skeleton but were lost in the mining process. The humerus is an
extraordinary element on account of its robust dimensions. It is very
stoutly built and represents a powerful limb. It is expanded at each
extremity and the width of its shaft is about equal to one-fourth of its
length. The ulna and radius present the same characters as the humerus,
_i.e._, in being robust, with stout shaft and expanded ends. The ulna
is slightly longer than the radius and has an expanded upper end. The
radius is short and does not have the proximal expansion. The carpus was
cartilaginous. Its position is represented by a blank space on the coal.
There are 4 digits preserved and in all probability this was the entire
number. The metacarpals are elongate and expanded at the extremities. The
first and second digits are represented nearly complete. The first digit
is extremely interesting in the possession of a claw-like terminal phalanx
which much resembles that of some lizards. There are 3 phalanges in the
first digit and 4 in the second. The phalangeal formula may have been
3-4-4?.

The ventral scutellation of this species is of an unusual character. It
consists of broad, imbricated scutes which are in a single piece and which
are arranged in the usual chevron pattern. The scutes were, apparently,
broadest in the middle and tapered somewhat at the extremities. This
character alone is sufficient for separating the genus from that of any
other known form.

The genus finds its nearest allies in the forms of the species of the
genus _Sauropleura_, in which Cope formerly located the present species.
The skull of the form described as _Tuditanus radiatus_ Cope is quite
similar to the present form, both in the sculpturing and arrangement
of the elements. The characters wherein the present form resembles the
species of _Sauropleura_ are the possession of broad pectoral plates
and strong, digitate limbs. The general form of the body and skull is
different in the two groups. It is slender in _Sauropleura_ and decidedly
stout, short, and heavy in Saurerpeton.

Measurements of the Type.

                                       mm.
  Length of specimen                   130
  Median length of skull                51
  Width of skull at posterior border    62
  Width of skull across orbits          48
  Length of orbit                       14
  Width of orbit                        10
  Interorbital space                    16
  Length of longest tooth preserve      14
  Length of shortest tooth preserved     1
  Length of the interclavicle           26
  Width of interclavicle, maximum       23
  Length of clavicle                    22
  Width of clavicle                     18
  Length of abdominal scutes            28
  Length of humerus                     19
  Width of humerus at upper end          6.5
  Length of ulna                        11
  Length of radius                       9
  Length of metacarpal                   3
  Length of first digit                 12
  Length of terminal phalanx             3.5
  Length of lower jaw on the curve      70
  Width of lower jaw, maximum            8
  Length of rib                         30


=Genus CTENERPETON Cope, 1897.=

  Cope, Proc. Am. Phil. Soc., XXXVI, p. 83, pl. iii, fig. 1, 1897.

Type: _Ctenerpeton alveolatum_ Cope.

The genus _Ctenerpeton_ was founded by Cope for the reception of a single
species which presents some very unusual characters. The form shows close
relationships to the genera _Urocordylus_ (334), _Œstocephalus_, and
_Ptyonius_. These genera agree with the present one in the possession
of very characteristic vertebræ which are signalized by the elongate
and ornamented characters of the neural and hæmal spines. These project
prominently from the body of the vertebra and have the ends of the
projections truncate and divided into fine points, thus causing the spine
to have much the appearance of a comb. The surface of the neural spine is
sometimes marked with a shallow groove. The spines are longer and more
slender in the genera _Œstocephalus_, _Urocordylus_, and _Ctenerpeton_
than they are in the species of the genus _Ptyonius_, where they are
short, although the usual pectinations are present.

The character on which this genus rests is the shelf-like extension (plate
23, fig. 2) of the abdominal plates. This is of a very unusual character
and entirely unknown in any other species of Carboniferous Amphibia.
The term Ctenerpeton has reference to the fact that the ends of these
shelf-like plates project in a pectination along the side of the abdomen.


=Ctenerpeton alveolatum Cope.=

  Cope, Proc. Am. Phil. Soc., XXXVI, p. 83, pl. iii, fig. 1, 1897.

  Moodie, Proc. U. S. Nat. Mus., 37, p. 24, pl. 10, 1909.

Type: Specimen No. 4475, U. S. National Museum, Lacoe Collection.

Horizon and locality: Linton, Ohio, Coal Measures.

The species rests on a single specimen (plate 19) from Linton, Ohio, and
is preserved on a block of bituminous coal. It is in a very good state
of preservation. There are present on the block of coal a part of the
right fore limb, the greater part of the dorsal portion of the animal,
and the anterior part of the tail. There are no evidences of hind limbs,
although this may not be taken as evidence that they were not present on
the animal. No thoracic plates have been observed. The chevron armature
is present beyond the cloacal region, but there are no evidences of the
specialized clasping organs which are apparently developed from the
abdominal armature in some forms (251).

Each dermosseous rod of the abdominal scutellation consists of three
pieces a median angulated portion and the two lateral parts which form
the shelf-like projection along the side of the abdomen (plate 23, fig.
2). The marginal chevron differs in form from the other plate, aside
from the fact that it is not angulated. The lateral shelf is composed of
flattened plates which articulate with the median piece, and at the place
of articulation there is a ridge present in the specimen. The exterior
plates are curved backwards and are somewhat attenuated distally. They
are broader than the median piece and differ also in the absence of the
characteristic alveoli. The median plate is angulated and is of more
slender proportions than the lateral pieces. Its ventral surface is
ornamented with a single row of closely placed alveoli which resemble in
a great degree the alveoli of the jaw of some small animal. The ventral
scutellation is broad anteriorly, but becomes more slender posteriorly and
shortly posterior to the cloacal region disappears.

[Illustration: MOODIE                                           PLATE 23

  1. Left leg and pelvis of _Ichthycanthus platypus_ Cope, from the
       Coal Measures of Ohio. × 1.7. Original the property of the
       Department of Geology of Columbia University. _c_=centrale;
       _F_=fibula; _fi_=fibulare; _Fe_=femur; _i_=intermedium;
       _Il_=ilium; _T_=tibia; _t, 1-5_=distal tarsalia; _ti_=tibiale;
       _V_=caudal vertebræ; _I-V_=digits.

  2. Ventral scutellæ of _Ctenerpeton alveolatum_ Cope, from the Coal
       Measures of Ohio. × 3.5. Original in U. S. National Museum.

]

The fore limb is represented by the upper portions of the ulna and radius
and 2 digits of the right hand. The digits are long and slender and
seem to represent digits I and II, since they show evidences of 3 and 4
phalanges respectively. The portions of the forearm preserved are too
meager for description.

The vertebræ have already been characterized as of the type first
described in Urocordylus. The neural fans are not much, if any, wider than
the hæmal fans. They are both situated on an elongate spine with a slender
base. The edges of the two fans are pectinated and the dorsal spine is
distinguished by the presence of a longitudinal groove in the center of
the spine. The length of the tail may have been considerable, judging from
the character of the vertebræ preserved

Measurements.

                                                        mm.
  Length of specimen                                   150
  Width of belly, maximum                               28
  Length of lateral chevron plate                        7
  Width of lateral chevron plate                         1.75
  Length from tip of lateral chevron to median angle    10
  Length of a caudal vertebra                           10
  Width of the same vertebra with spines                20
  Height of neural spine                                 8
  Height of hæmal spine                                  8
  Width at distal end of hæmal spine                     3
  Width at distal end of neural spine                    3.5
  Length of foot, as preserved                          12


=Genus LEPTOPHRACTUS Cope, 1873.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 340, 1873.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 399, 1875.

  Cope, Proc. Am. Phil. Soc., XX, p. 461, 1882.

Type: _Leptophractus obsoletus_ Cope.

The genus was established on various parts of the cranium of a large
amphibian. The only parts which can with certainty be referred to the
genus are the upper and lower jaws of 3 specimens. These bear large teeth,
round in section at the base, but with acute compressed apex, with a
cutting-edge on the anterior face; the enamel is delicately grooved, as an
external indication of the labyrinthic structure. A characteristic feature
is seen in the presence of a large elongate tooth in the upper jaw, in the
position of a canine which much exceeds in length any of the others. The
sculpture of the cranium is but little marked in the known specimens. In
the type the lower jaw is marked with inosculating grooves. Three species
are known, which are among the largest of the Linton Amphibia.


=Leptophractus obsoletus Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 340, 1873.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 399, 1875.

  Cope, Proc. Am. Phil. Soc., XX, p. 461, 1882.

Type: Specimen Nos. 55 G and 57 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures.

The species was about as large as an adult Florida alligator, and probably
exceeded or at least equaled in size any of the Carboniferous Amphibia.
The following account is taken directly from Professor Cope's "Batrachia
of the Ohio Coal Measures" (123). The description has been verified from
an examination of the type material.

"The teeth are rather distantly grooved for some distance above the base.
They are of different sizes; the smaller are compressed, and with fore and
aft cutting edges. The external surface of the dentary bone is marked with
short oblique grooves along its middle region; above these are grooves
which inosculate, forming a figure like an open net dragged in the long
direction.

"Excepting the grooves the teeth are smooth. The smaller ones are close
together and their crowns are curved backwards; the larger ones are at
more remote intervals; both have enlarged bases. Whether both forms are in
the same series I can not determine. There are from four to five of the
smaller to an inch.

Measurements of Type of Leptophractus obsoletus Cope.

                                     mm.
  Depth of fragment of jaw           75
  Length of smaller teeth            19
  Length of longer tooth             23
  Width of vertex at middle scuta   176
  Width of paired median scuta       56
  Width of single scute              36
  Length of single scute             48

"Some vertebræ were found at the same locality, but there is no evidence
as to the species to which they may have pertained. They are short,
concave on one end, and probably so on the other. The centrum of one is 12
mm. in diameter; neural spines injured." (Geol. Surv. Ohio, II, pt. II,
pl. 39, fig. 3.)

"A third and larger specimen was found by Professor Newberry during the
field season of 1874. It includes an oblique view of one side, and the
top of the cranium from the posterior part of the orbits to the end of
the muzzle, with the corresponding part of the alveolar region of the
dentary bone, with teeth. The bones of the skull appear to have been
rather light, and though the surface is irregular, the sculpture consists
only of shallow impressions of varying size and intervals. The orbits are
also badly defined, but appear to have been large, and separated by a
narrow frontal bone. The premaxillary bone is preserved, and shows clearly
the sutures that separate it from its fellow and from the maxillary. A
large foramen--perhaps the nostril--separates it from the maxillary, so
that it forms an irregular crescent. It supports two teeth, of which the
anterior is the larger, but there were perhaps others in advance, as the
alveolar border is imperfect towards the end of the muzzle. The anterior
two teeth of the maxillary bone are followed by a strong groove which
rises towards the sides of the muzzle. At first sight this gives the
impression of the maxillo-premaxillary suture, and makes it appear that
both the premaxillary bones are preserved, and that the foramen above
described separates the premaxillary spines, instead of representing the
nostril. The cutting edges of the teeth of these bones have, however, one
direction, whence they represent one side of the cranium only; were both
sides represented, the directions of the tooth axes would be reversed.

"The premaxillary and maxillary teeth exhibit a cutting edge on the outer
posterior margin of the distal half; the base of the crown is subround
in section. The line-like grooves are distinct but not numerous, their
intervals measuring 75 mm. Beyond them the enamel is smooth. The second
maxillary tooth is larger than the first, which is equal to the last
premaxillary. The third and fourth maxillaries are equal to the second,
but the fifth is larger and longer, exceeding all the others. The teeth of
the dentary bone differ from those of the upper jaw in having the cutting
edge of the crown on the anterior aspect, while the posterior border is
obtuse. There is an obtuse cutting edge on the posterior margin of the
anterior mandibular teeth.

"This description is derived from an adult animal, as the maxillary teeth
in some instances are partially worn away by friction on their anterior
and outer faces."

Measurements.

                                                    mm.
  Length of maxillary bone preserved                146
  Length of same supporting five teeth               73
  Length of first maxillary tooth                    15
  Diameter of same at base                            6
  Diameter of second at base                          8
  Length of basis of fifteen teeth of the dentary   145


=Leptophractus dentatus new species.=

Type: Specimen No. 10850, American Museum of Natural History. Collected by
Dr. J. S. Newberry.

Horizon and locality: Linton, Ohio, Coal Measures.

[Illustration: Fig. 36. Mandible of _Leptophractus dentatus_ new species,
from the Linton, Ohio, Coal Measures. × 1. Original in American Museum of
Natural History.]

The type is a single right mandible, nearly entire, of a rather large
animal. The specific characters for the separation of the new form from
the previously described _L. obsoletus_ and _L. lineolatus_ are the
smaller size and slenderness of the mandible, associated with uniform
teeth, which are slender and delicately fluted.

There are 17 teeth preserved, the largest of which is 8 mm. in length.
From the posterior tooth the series gradually descends to half this length
0.5 inch from the anterior end of the mandible.

The exact form of the mandible can not be determined, but so far as can
be seen it is very slender, coming almost to a point at the anterior end.
The posterior portion is wide, but apparently not very heavy. There is a
fragment associated with the specimen which discloses a few teeth, but its
position in the cranium can not be determined.

Measurements of the Type of Leptophractus dentatus Moodie.

                                          mm.
  Length of mandible, as preserved         80
  Anterior width of mandible                3
  Posterior width                          28
  Length of most anterior tooth             4
  Length of tenth posterior tooth           7
  Width of this tooth at base               3

=Leptophractus lineolatus Cope.=

  Cope, Proc. Am. Phil. Soc., XVI, p. 576, 1877.

Type: Specimen No. 1088 G, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures. (Plate 22, fig. 1.)

Cope's description of this species, to which I have nothing to add, is as
follows:

  "This species is based on portions of the skull of two individuals of
  large size. Both upper and lower jaw with teeth are represented and
  the teeth are of very large size. The deepest element preserved has
  been provisionally referred to the mandible and will be so described.
  This element bears two types of teeth in very heterodont fashion. The
  teeth in the back portion of the jaw are rather short and slender.
  The teeth more anteriorly are, some of them, very long, rather stout,
  with their bases longitudinally fluted, as are they all v The longest
  tooth in the jaw measures slightly less than an inch. The bone is not
  well preserved, but seems to have been ornamented with grooves of no
  great depth. The most anterior teeth of the jaw are smaller than the
  posterior ones.

  "The upper jaw is set with teeth which are more uniform in size and
  there is but little tendency to heterodonty. These teeth are also
  striated at their base and all end in a sharp point. They are all,
  apparently, straight. There is no tendency to curve as there is in the
  genus _Macrerpeton_. The upper teeth are more closely set than are
  those of the lower jaw, which are rather distantly placed.

  "Another specimen of a smaller individual presents the same portions
  of the skeleton and the same characters. It is possible that this
  skull will be found to belong to _Ichthycanthus ohiensis_ Cope, which
  is based on very large vertebræ and limb bones. The remains described
  as _Leptophractus lineolatus_ are, however, unlike any other skull
  remains which are thus far known.

  "This species represents one of the largest types of the Carboniferous
  Amphibia of Ohio. It probably attained a length of several feet. It
  was also the most carnivorous of any of the forms."

Measurements of the Type Specimen of Leptophractus lineolatus Cope.

                                                         mm.
  Length of specimen, as preserved                       98
  Depth of dentary bone at the middle                    30
  Anteroposterior diameter of mandibular tooth at base    3.5
  Length of a posterior mandibular tooth                  9
  Length of longest tooth in jaw                         22
  Anteroposterior diameter of the same at base            6
  Length of small maxillary tooth                         7
  Anteroposterior diameter of same at base                2

Collected by Dr. J. S. Newberry. Other specimens of the species are Nos.
1086 G and 1087 G, American Museum.


=Eurythorax sublævis Cope.=[C]

[Footnote C: Dr. Hussakof now regards (Bull. Amer. Mus. Nat. Hist., vol.
35, p. 128, 1916) the type specimen of this species as an opercular
element of one of the dipnoan fishes [_Sagenodus sublævis_ (Cope)]. The
discussion is left here, however, as a matter of historical interest.]

  Cope, Proc. Am. Phil. Soc., p. 177, 1871.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 401, pl. xl, fig. 4, 1875.

Type: Specimen No. 8605 G, American Museum of Natural History, Collection
of Dr. J. S. Newberry.

Horizon and locality: Linton, Ohio, Coal Measures.

The genus and species were established on a single, large, almost perfect
interclavicle of peculiar form. It may or may not be distinct, but it
can not be associated definitely with any known genus, so that it will
be designated as Cope described it. It exhibits on its outer or lateral
borders broad, smooth surfaces for the contact of the overlapping margins
of the lateral plates. The form is subround, with a large excavation from
the posterior margin on each side. The narrowed portion left in the middle
behind has a convex outline. Some delicate radiating grooves occur on the
exposed surface, but they are very shallow.

Measurements of Type.

                               mm.
  Length of interclavicle      71.5
  Greatest width               78
  Width of lateral concavity   39

[Illustration: Fig. 37.--So-called interclavicle of _Eurythorax sublævis_
Cope. (_Sagenodus._) No. 75. (After Cope.)]



CHAPTER XXII.

THE MICROSAURIAN FAMILY ICHTHYCANTHIDÆ, FROM THE COAL MEASURES OF OHIO.


=Family ICHTHYCANTHIDÆ new family.=

This family is the most recently recognized group of the Linton fauna. Its
members, of which there are two known species, are distinct from all other
Coal Measures Amphibia in the possession of an osseous tarsus (483, 484),
with its associated reptile-like limb bones. There are preserved fine
scutellæ in a large patch near the vertebral column. The vertebral spines
are broad and heavy, with the vertebral centra amphicœlous.


=Genus ICHTHYCANTHUS Cope, 1877.=

  Cope, Proc. Am. Phil. Soc., p. 573, Feb. 3, 1877 (Pal. Bull. 24).

  Baur, Beiträge zur Morphogenie des Carpus und Tarsus der Vertebraten,
    I Theil, p. 16, 1888.

  Cope, Trans. Am. Phil. Soc., XVI, p. 289, fig. 1, 1888.

  Moodie, Science, n. s., XLI, No. 1044, p. 34, 1915.

  Moodie, Am. Jour. Sci., XXXIX, pp. 509-512, fig. 2, May, 1915.

Type: _Ichthycanthus ohiensis_ Cope.

The generic characters are derived from the characters presented by the
posterior dorsal and caudal vertebræ, with adjacent parts. The posterior
limbs are well developed, with distinct tibia and fibula, osseous tarsus,
and 5 digits. Ribs elongate, simple, curved. Abdominal armature consisting
of bristle-like rods in anteriorly directed chevrons. Dorsal vertebræ not
elongate, with simple neural spines. Tail large, its vertebræ ossified,
and furnished with slender chevron bones which terminate in a hæmal spine.
Neural spines broad and directed backwards; the caudal series somewhat
resembling that of a fish. All the centra are amphicœlous.

This genus differs from all those with enlarged and sculptured neural
spines, and from those with abdominal scutes. It is equally distinct from
those without ribs, abdominal rods, or limbs. It is possible that some of
the species referred to _Tuditanus_, in which these parts are unknown,
may belong to it, or that it may be established on a small species of
_Leptophractus_, a genus known only as yet from the skull. With our
present imperfect knowledge of the Linton forms it seems best to refer _I.
ohiensis_ and _I. platypus_ to this distinct genus, _Ichthycanthus_.


=Ichthycanthus ohiensis Cope.=

  Cope, Proc. Am. Phil. Soc., 1877, p. 573 (Pal. Bull. 24).

Type: Specimen in the American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures. Collected by Dr. J. S.
Newberry, in the summer of 1876.

The centra of the dorsal vertebræ are about as long as deep, and their
sides are deeply concave; there are 4 anterior to the pelvis which are
without ribs. The caudal vertebræ are robust, and 7, from the first,
support a small tubercle-like diapophysis. The chevron bones are short and
acuminate; the neural spines are a little shorter, narrow, and truncate,
and directed backwards at the same angle as the chevron bones. They are
much reduced on the eighteenth caudal vertebra, where the chevron bones
are considerably longer.

The abdominal rods are quite slender. The hind limb is quite stout for
this order. The femur is regularly expanded at both extremities, but the
distal is deeply and openly grooved, distinguishing the condyles, while
the proximal end is plane. There is no trochanter visible. The ulna
and radius are well separated, and are three-fifths the length of the
femur. There is a large fibular tarsal bone of a subquadrate outline. In
immediate contact with it is probably the external digit with 5 phalanges
or segments; the ungual is simply conic. The femur is as long as 5 dorsal
vertebræ. The ribs have expanded, undivided heads, and extend to the
abdominal armature.

Measurements of the Type of Ichthycanthus ohiensis Cope.

                                             mm.
  Length of last 10 dorsal vertebræ           47
  Length of first 23 caudal vertebræ         117
  Length of a posterior rib                   29
  Length of a posterior dorsal vertebra        5
  Length of twenty-second caudal vertebra      5
  Length of femur                             25
  Proximal diameter of femur                   8
  Width of lower leg                           9
  Length of fibula                            15
  Length of tarsal bone                        6
  Length of digit                             27


=Ichthycanthus platypus Cope.=

  Cope, Proc. Am. Phil. Soc., pp. 574, 575, 1877.

  Cope, Trans Am. Phil. Soc., XVI, p. 289, fig. 1, 1888.

  Baur, Beiträge zur Morphogenie des Carpus und Tarsus der Vertebraten,
    I Theil, p. 16, 1888.

  Moodie, Science, n.s., XLI, No. 1044, p. 34, 1915.

  Moodie, Am. Jour. Sci., XXXIX, pp. 509-512, fig. 2, 1915.

Type: Specimen No. 79540, and obverse, Department of Geology, Columbia
University. (Plate 23, fig. 1.)

Horizon and locality: Linton, Ohio, Coal Measures.

This amphibian is represented by the same portions of the skeleton as the
preceding species, furnishing a good basis for comparison. It is very well
preserved, displaying the characters, especially of the hind foot, which
is almost entirely represented.

Several features distinguish it from the _I. ohiensis_, one of which is
of more than usual value if correctly indicated by the fossil. There are
10 vertebræ from the anterior end to the sacrum preserved in place, and
none of them supports a rib, nor are there any ribs visible anywhere on
the block of shale. I suspect that they exist on more anterior vertebræ,
or may have been displaced to a more anterior position than they normally
occupy. The abdominal chevrons are more anterior in position than are
those of the _I. ohiensis_. The hind legs are longer than in that species;
in this one the femur equals 7.5 vertebral centra in length. The external
digit, on the other hand, while bearing 5 phalanges, is distinctly
shorter. The fibular tarsal is of a transverse oval, not quadrate, form.

The dorsal centra are shorter and deeper than long; the neural arches are
elevated, with short but distinct zygapophyses, and a flat, subquadrate,
superiorly truncate, neural spine. They bear short, vertically compressed
diapophyses near the base of the arches. The neural spines of the caudal
vertebræ become rapidly more slender, and also diminish in length, while
the zygapophyses are continued to the fifteenth vertebra. The chevron
bones are slender, and inclose a moderate hæmal opening.

[Illustration: MOODIE                                           PLATE 24

  1. Photograph of the type specimen of _Pelion lyelli_ Wyman, from
       the Ohio Coal Measures. Supposed to represent the ancestral form
       of the Salientia. × 2. Original in American Museum of Natural
       History.

  2. Scales of _Cercariomorphus parvisquamis_ Cope, a microsaur from
       the Ohio Coal Measures. × 10. Original in American Museum of
       Natural History.

  3. Type specimen of _Cercariomorphus parvisquamis_ Cope, from the
       Ohio Coal Measures. Original in American Museum of Natural
       History. × 0.75.

]

The femur is gradually expanded to the extremities. Proximally there is
a trochanteric ala, besides the obtuse head. Distally the condyles are
well distinguished, the external or fibular being truncate. The fibula is
less than three-fifths the length of the femur, and is expanded at both
extremities. Two proximal tarsals are distinct; the one next the fibula
is larger than the other and transverse suboval in form. It has a median
dividing ridge as though composed of fibulare and intermedium coössified.
The tibiale is subtriangular. There are five distinct phalangeal tarsals.
The toes are, in the order of their lengths, beginning with the shortest,
1-2-5-3-4. Their phalanges (including metatarsals) are, in the proper
order, commencing with the hallux, 3-3-4-5?-5, the distal end of the
fourth finger being lost. These bones are rather stout, and the unguals
are simply conic. The form of the foot is short and wide. The number of
the phalanges is nearly similar to that found in _Amphibamus grandiceps_,
excepting that in that species the fifth digit has but 4. They are more
numerous on most of the digits in _Sauropleura digitata_. Cope (Trans.
Am. Phil. Soc., XVI, 289, fig. 1, 1888) contributed the following note on
_Ichthycanthus platypus_:

  "A reëxamination of the type specimen of this species from the Coal
  Measures of Ohio, preserved in the Museum of Columbia College, New
  York, enables me to refer this species to the Rachitomi. The neural
  spines are distinct, showing that it belongs, probably, to the
  Eryopidæ. As the skull is not preserved, I can not determine the genus
  positively, but refer it for the present to Eryops. I append a figure
  of the posterior foot, which displays the characters of the tarsus
  of this group for the first time. The number of tarsals is as in a
  Theromorph reptile, except that two elements represent the cuboid
  bone as in the reptile, _Stereosternum tumidum_ Cope; giving five
  elements in the distal tarsal row. There is but one centrale and no
  intermedium. Two fragments of caudal vertebræ adhere to the specimen."

Measurements of Ichthycanthus platypus Cope.

                                               mm.
  Length of 10 dorsal vertebræ                 45
  Length of 15 caudal vertebræ                 55
  Length of centrum of a dorsal                 3.8
  Total elevation of a posterior dorsal        14
  Length of femur 32 Length of first digit     10
  Diameter of femur medially                    4.5
  Diameter of femur distally                    8.3
  Length of fibula                             18
  Diameter of fibula proximally                 7
  Width of sole at second row of tarsal bones  17
  Length of foot to end of third digit         31
  Length of third digit                        22
  Length of fifth digit                        20

The writer has had the privilege of restudying this interesting specimen
and has already (484) described the foot and tarsus, as follows:

The only known specimen of this anomalous amphibian is incomplete,
representing the posterior half of the skeleton, and an abundance of
ventral scutellæ or calcified myocommata. The block of coal containing
these interesting remains is from Linton, Ohio, and is preserved in the
geological collections of Columbia University, from which institution
Professor Grabau very courteously forwarded it for study.

_Ichthycanthus platypus_ was described by Cope from the Linton, Ohio, Coal
Measures, locating it doubtfully in the Permian genus _Eryops_ on account
of the unusual condition of the tarsus and reconsidering a former decision
in favor of a Coal Measures genus _Ichthycanthus_. In this disposition
of the species into the Permian genus he is followed by Hay (317); but
Baur (28) regarded the form as a member of the Coal Measures genus
_Ichthycanthus_, after commenting on the later definition by Cope. The
type of the genus, _Ichthycanthus_, to which Cope first allied the species
under consideration, is _I. ohiensis_, a supposed amphibian from the Coal
Measures of Linton, Ohio, founded on incomplete material.

The form combines in an unusual and remarkable degree reptilian and
amphibian characteristics. The leg bones, pelvis, and tarsus are all
strikingly reptilian, but the phalanges in the arrangement of elements
are so typically amphibian that if we had no other means of diagnosis we
would incline to locate this Coal Measures species among the Amphibia.
The leg (plate 23, fig. 1) recalls in its structure that of another
Coal Measures species, _Eosauravus copei_ Williston, which is, however,
clearly a reptile. While there is a general degree of similarity between
the foot structure of _Eosauravus copei_ and _Ichthycanthus platypus_,
yet there are very great differences in the phalangeal formula and the
arrangement of the tarsal elements. These differences are clear and
indicate a separation of the two species into distinct classes. The
phalangeal formula in the _Eosauravus_, 2-3-4-5-4, is typically reptilian;
while in the _Ichthycanthus_, 2-2-3-3-3, it is amphibian. The tarsus of
the _Ichthycanthus_ is amphibian in the presence of an intermedium, but
this is very small and the remaining tarsal structures have nothing which
might not be found in an early reptile. There may be a single or even two
centralia in the reptilian tarsus among the early forms.

The amphibian nature of the species having thus been established,
it remains to give a detailed account of its skeletal anatomy, with
comparative references to such other ancient forms as are available.
Little can be said of the vertebral column, since only the molds of a few
vertebræ remain, and these are so obscured by a closely adherent pellicle
of carbonaceous material that their form can not be distinctly discerned.
They are high, with relatively broad neural spines. There are no ribs
preserved. The pelvis is obscured, but it is possible to determine the
presence of an elongate ilium and an ischium. The leg of the left side
is the best preserved of all the elements, and it is to this that our
attention will be confined. The opposite leg is not so complete, yet all
the long bones and a part of the tarsus are preserved with sufficient
clearness to corroborate the findings of the left side.

The femur, as has been stated, is reptilian in appearance. This is due
to the well-rounded articular surfaces, as though the endochondrium were
well developed, and to the large development of the greater and lesser
trochanters, which are quite prominent, though these are distorted and
depressed in fossilization. The bone is stout and well built and its form
suggests an active habit of life. The tibia and fibula are separate, and
do not otherwise have sufficiently noteworthy characters to call for a
special description in this place, except to note an unusual anterior
crest on the tibia. To the lower ends of these bones articulate the first
row of tarsal elements, the tibiale, intermedium, and fibulare. The tarsus
is composed of 9 elements arranged in 3 rows. The proximal row is composed
of the tibiale, the intermedium, and the fibulare. On the edge of the
tibiale there lies a portion of one of the caudal vertebræ, so that the
form of this tarsal element is slightly obscured. The intermedium is a
small, rounded element lying between the larger elements. The fibulare is
rectangular and projects a considerable distance out from the tibia, but
articulates directly with the large lateral distal tarsal. The centrale
is triangular in form and is opposed directly by the tibiale and tarsalia
1 to 3. The phalanges are robust in appearance. The entire foot gives
one the impression of a very broad structure. The ungual phalanges were
apparently bluntly clawed.



CHAPTER XXIII.

SUPPOSED MICROSAURIAN SPECIES OF UNCERTAIN RELATIONSHIP.


The following three species are so unusual and so incompletely known that
they can not be considered with any of the above families: _Brachydectes
newberryi_ Cope, Linton, Ohio; _Amblyodon problematicum_ Dawson, Nova
Scotia; _Proterpeton gurleyi_ Moodie, Danville, Illinois.


=Genus BRACHYDECTES Cope, 1868.=

  Cope, Proc. Phila. Acad. Nat. Sci., 1868, p. 214.

  Cope, Trans. Am. Phil. Soc., 1868, p. 14.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 388, 1875, pl. xxvii, fig. 2.

Type: _Brachydectes newberryi_ Cope.

Cope (Geol. Surv. Ohio, vol. II, pt. II, p. 388, 1875), says:

  "This genus is indicated by two rami of a mandible and a portion of a
  premaxillary only. These, when compared with those of _Œstocephalus_
  and _Tuditanus_, from the same locality, and with others described by
  authors, are so much stouter, i.e., shorter and more elevated, that
  they evidently belong to a genus unlike either. The genus further
  differs from _Œstocephalus_ in having the teeth of equal size to the
  posterior part of the series; that is, to the base of the elevated
  coronoid process. The teeth are elongate cylindrical cones, with their
  acute tips turned a little posteriorly. The fractured ones display a
  large pulp cavity. The three premaxillaries preserved are similar, but
  without curvature at the tips. They do not exhibit striæ or any other
  sculpture.

  "So far as the remains known go, the genus is nearer _Hylerpeton_
  than any other. According to Dawson, that genus is provided with a
  large canine-like tooth, at the anterior extremity of the maxillary,
  on the inner row, which is inserted into a distinct socket. No such
  tooth appears among those of this genus. The latter does not give any
  indication of the very elevated coronoid process of _Brachydectes_,
  though the external portion of the dentary bone in that region being
  lost, little can be said about it."


=Brachydectes newberryi Cope.=

  Cope, Proc. Phila. Acad. Nat. Sci., p. 214, 1868.

  Cope, Trans. Am. Phil. Soc., 1868, p. 14.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 388, pl. xxvii, fig. 2, 1875.

Type: Specimen No. 8604 G, American Museum of Natural History.

Horizon and locality: Linton Ohio, Coal Measures. Cope (Geol. Surv. Ohio,
vol. II, pt II, p. 388, 1875) says of this form:

  "The species is represented by one nearly perfect ramus mandibuli, one
  dentary bone and one premaxillary, probably not complete.

  "The dentary bone appears to have been attached by suture to the
  articular and angular, as its free margin has very much of the outline
  of that suture in _Amphiuma_ and lizards. The coronoid process
  would also seem to be a part of the same bone as in _Amphiuma_ and
  _Menopema_, and not composed of the coronoid bone as in lizards. It
  rises immediately behind the last tooth, and displays no suture.

  "The lower portion of the dentary is prolonged into an acute angle.
  This is separated by a deep and wide concavity from the superior
  posterior prolongation, which is obtuse, and rises at once into the
  coronoid process. Teeth on this dentary, seven; the same number is
  on the preserved ramus; this number is suspected to be complete, or
  nearly so. The teeth terminate at the obvious termination of each
  ramus, which is, it is true, slightly obscured. These teeth are the
  longest in the Microsauria in relation to the depth of the ramus,
  equaling the largest in _Œstocephalus_. They are doubtless exposed,
  as are some of those of the last-named genus, by the splitting away
  of the outer parapet of the dentary bone. As no traces of alveoli
  have been thus rendered visible I suspect the dentition to have been
  acrodont, as in some existing Batrachia.

  "No external surface of the mandible remains, but there are no
  impressions of sculpture on the matrix. A little external face of the
  premaxillary displays none.

  "The species is dedicated to Professor John S. Newberry, the able
  director of the Geological Survey of Ohio, and discoverer of most of
  the Batrachia herein described."


Measurements of the Type.

                                              mm.
  Length of ramus of mandible (imperfect)     22
  Depth at last tooth                          5
  Length of exposed tooth                      3.5
  Length of dentary                           16
  Depth at coronoid process                    7.5
  Depth at first tooth                         3


=Genus PROTERPETON new genus.=

Type: _Proterpeton gurleyi_ Moodie.

Known from a single vertebra. Spine very high and heavy, the neural canal
large.


=Proterpeton gurleyi new species.=

Type: Specimen No. 13,296, Walker Museum, University of Chicago.

Horizon and locality: Coal Measures near Danville, Illinois.

The vertebra, as preserved, is well characterized by the figure (plate
22, fig. 2). The spine is high and heavy, the neural canal is large, and
the centrum reduced. The form is very unusual. It is apparently from the
cervical region, as there are no indications of zygapophyses, transverse
processes, or hæmal arches, although they may have been abraded;
apparently not, however. The type specimen was discovered near Danville,
Illinois, about the horizon of the Danville coal, so that it is quite high
in the Allegheny series of the Pennsylvanian and of about the same horizon
as the phalangeal bone from Breeze, Illinois, which may be provisionally
associated with this form. There is no assurance that Proterpeton gurleyi
is an amphibian. The vertebra may have belonged to a fish.

Measurements of the Type of Proterpeton gurleyi Moodie.

                                                   mm.
  Entire height of vertebra                        24
  Width at side of neural canal                    21.5
  Width of neural canal                            13
  Height of neural canal (crushed?)                 6.5
  Width of vertebral centrum anteroposteriorly      5.5
  Height of neural spine from top of neural canal   9


=Genus AMBLYODON Dawson, 1882.=

Dawson, Phil. Trans. Roy. Soc. London, pt. 11, p. 644, pl. 40, figs.
57-61, 1882.

Type: _Amblyodon problematicum_ Dawson.

This genus was described by Dawson in 1882 from very imperfect remains. He
says that it is "characterized by stout cylindrical teeth, blunt at the
apices; but otherwise imperfectly known."


=Amblyodon problematicum Dawson.=

  Dawson, Phil. Trans. Roy. Soc. London, pt. II, p. 644, pl. 40, figs.
    57 to 61, 1882.

Type: Specimen No. 3061-10, Peter Redpath Museum, McGill University.

[Illustration: Fig. 38.--Skeletal elements of _Amblyodon sp._ from the
Coal Measures of Nova Scotia. _a_, tooth, × 25; _b_, section of tooth, ×
25; _d_, fragment of thoracic plate; _f_, shaft of limb bone; _e_, rib.]

Horizon and locality: Coal Measures of Nova Scotia.

A fragment of a jaw 1 cm. in length has 10 cylindrical teeth, simple and
smooth, with large pulp cavities and rounded regularly at the apices.
With these are 4 vertebræ of the usual type, measuring together 1 cm.
Fragments of cranial bones also occur and are obscurely pitted. There is
also what seems to be the shaft of a limb bone and a few oval scales. A
flat and somewhat rhombic bone, with a style at one side, may possibly be
a thoracic plate or possibly a parasphenoid.

The material is too scanty for any satisfactory description of this
animal, but it is provisionally named _Amblyodon problematicum_.



CHAPTER XXIV.

THE TEMNOSPONDYLOUS AMPHIBIA OF THE COAL MEASURES OF NORTH AMERICA.


DEFINITION OF THE ORDER TEMNOSPONDYLIA, ZITTEL. 1887.

  Zittel, Handbuch der Paleontologie, Abth. 1, Bd. 3, p. 384, 1887.

  Terrestrial or semi-aquatic vertebrata; skull bones pitted and
  grooved; lateral-line canals present in well-developed form; pineal
  foramen sometimes absent; sclerotic plates present; vertebræ
  rachitomous or embolomerous; notochord partly persistent; one or two
  sacral vertebræ; tail present, long or short; limbs and girdles well
  developed; limb bones well ossified and bones of arm and leg separate;
  pectoral and pelvic girdles composed of the usual stegocephalian
  elements; an osseous pubis present; a cleithrum present on the
  scapula; carpus and tarsus ossified, carpals n and tarsals 12 in
  one form; phalangeal formula, 2, 3, 3, 4, 2 for the hand and 2,
  3, 3, 3, 2 for the foot; fore and hind limbs pentadactyl in a few
  forms; venter covered with an armature of osseous scutes, sometimes
  overlapping; skin of back bare or armored with heavy plates; ribs
  heavy, double-headed, curved and moderately long, or short; body short
  and heavy, as compared to skull about 2 to 1.

Range: Coal Measures to upper Permian.

Distribution: North America: Illinois, Kansas, Oklahoma, Texas, and
Pennsylvania; Europe: Germany, Bohemia; France; Asia: India.


=Family CRICOTIDÆ Cope, 1884.=

  Cope, Am. Nat., XVIII, p. 38, 1884.

  General form of the body elongate, with triangular skull and short,
  stout limbs. Snout narrow, orbits large, elongated oval, situated near
  the middle of the skull. External bones faintly sculptured, sensory
  canals conspicuous, parietal foramen large. Teeth conical, of unequal
  size. Presacral vertebræ composed of horseshoe-shaped pleurocentra
  and hypocentra, the former alone supporting the neural arch. In the
  caudals the pleurocentra and hypocentra form complete rings, and both
  elements take part in the support of the neural arch, but the hæmal
  arch is borne exclusively by the hypocentra. A close abdominal armor
  of imbricate scales, arranged in a chevron pattern. Caudal vertebræ
  numerous. Chevrons coössified with the intercentra.


=Genus SPONDYLERPETON Moodie.=

  Moodie, Kans. Univ. Sci. Bull., vi. No. 2, p. 355, 1912.

Type: _Spondylerpeton spinatum_ Moodie.

The genus is based on a specimen consisting of 9 imperfect vertebræ,
from the caudal region of a relatively large amphibian. The present
genus exceeds _Diplospondylus_ from the Gaskohle of Bohemia (251)
by twice its size and is about two-thirds the size of _Cricotus
heteroclitus_ Cope (98) from the Permian of Kansas. The vertebræ are
twice as high as wide, differing thus from _Cricotus_, in which the
vertebræ are nearly circular. A character which is of great importance
is the large size of the intercentrum, which almost equals the
pleurocentrum in size. It is similar to the pleurocentrum in shape,
except for the attached neurocentrum and chevron on the latter. The
present genus differs from _Diplospondylus_ in the greater length of
the intercentrum and pleurocentrum, in the greater size, in the larger
proportions of the neurocentrum, and the greater proportionate size of
the intercentra.


=Spondylerpeton spinatum Moodie.=

  Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 355-357, pl. 8, figs. 1
    and 2; pl. 9, fig. 1, 1912.

Type: Specimen No. 793 (26) and obverse, Yale University Museum.

Horizon and locality: Mazon Creek, near Morris, Illinois.

The species is very imperfectly known. Sufficient is present, however, to
show its wide generic differences from other forms of the Cricotidæ. These
characters are of a phylogenetic nature and indicate the more primitive
nature of the present form, as we would expect from its geological
position. The sutures separating the four vertebral elements are clearly
apparent. The pleurocentral-neurocentral suture is apparent in 4 vertebræ.

[Illustration: Fig. 39. The vertebræ of _Spondylerpeton spinatum_ Moodie,
the only known temnospondyle from the the Mazon Creek shales. × 1. _hy_,
hypocentrum; _inc_, intercentrum; _pc_, pleurocentrum; _nc_, neurocentrum.]

There is but a single pleurocentrum preserved complete. This shows the
form of the attached neurocentrum and chevron, which corresponds to the
hypocentrum pleurale according to Fritsch. The pleurocentrum is flattened
laterally, with a rather large canal for the notochord. Its sides are
marked with 4 longitudinal grooves. Surfaces for the attachment of the
ribs are not present, and for this reason, as well as the presence of
chevrons, the vertebræ are supposed to be caudals. As such they represent
an animal of some 3 or 4 feet in length. It was the giant of the Mazon
Creek Amphibia. (Plate 4, figs. 1, 2.)

Attached to the upper side of pleurocentrum by a sutural union occurs
the neurocentrum. The neural arch is quite large and is oval in outline,
although somewhat constricted at the tip. The spine of the neurocentrum is
rather long and broad at the base, measuring 12 mm. across the anterior
zygapophysis. The neurocentrum is laterally flattened and ends in a rather
acute and somewhat rugose point. It was probably tipped with cartilage.
The anterior zygapophysis occurs well down on the neurocentrum, its lower
edge being 5 mm. from the suture separating the pleurocentrum and the
neurocentrum. The posterior zygapophysis occurs quite high up on the
neurocentrum and lies at a distance of 15 mm. from the pleuro-neurocentral
suture, thus indicating an extreme posterior inclination of the neural
spine. The posterior zygapophysis of the best preserved vertebra is
separated from its mate, the anterior zygapophysis, in the next succeeding
vertebra by a space of 5 mm.

The ventral surface of the pleurocentrum bears a structure, which is,
without doubt, a chevron, although the character of its opening can not
be determined. It is elongated and is united by a broad base to the
pleurocentrum. Its union is by a clearly defined suture, which is apparent
in 3 vertebræ. The condition represented by the specimen duplicates almost
exactly the condition figured by Cope for the caudal region of Cricotus
Cope.[D]

[Footnote D: COPE, E. D., Trans. Am. Phil. Soc., XVI, p. 246, 1890.]

The intercentrum of the present form is fully as large as the
pleurocentrum. The significance of this has already been mentioned. The
body of the centrum is pierced by a large notochordal canal.

Measurements of the Type of Spondylerpeton spinatum Moodie.

                                                   mm.
  Length of specimen                               60
  Length of pleurocentrum                          11.5
  Height of pleurocentrum to base of neurocentrum  20
  Length of neurocentrum                           33
  Width of neurocentrum at base                     9
  Width across anterior zygapophysis               12
  Width across posterior zygapophysis              10
  Length of intercentrum                           10
  Height of intercentrum                           10.5
  Height of chevron                                 3
  Length of chevron                                18
  Width of notochordal opening in centrum           5
  Height of same                                    4.5
  Height of neural canal                           12
  Greatest width of neural canal                    6


=Family ERYOPIDÆ Cope, 1882.=

  Cope, Am. Nat., XVI, p. 334, 1882.

  Large, terrestrial or amphibious vertebrata; skull bones deeply marked
  with pits and grooves which take the form of lateral-line canals;
  infra- and supraorbital canals, antorbital commissure, jugal canal,
  and occipital cross-commissure of the lateral-line system present
  in _Eryops megacephalus_ Cope; carpus and tarsus osseous; pubis an
  osseous plate, surrounded in life by a large amount of cartilage; fore
  and hind limbs pentadactyl; orbits, in the typical genus, located far
  back on the skull and near the median line; cleithrum present on the
  scapula; vertebræ rachitomous, the intercentrum supporting the arch in
  the dorsal region; parasphenoid well-developed or reduced; teeth on
  pterygoids, palatines, prevomers, and parasphenoid.

Range: Upper Pennsylvanian to Permian.

Distribution: America, Europe, Asia.


=Genus ERYOPS Cope, 1877.=

Type: _Eryops megacephalus_ Cope.

  Skull long, comparatively narrow; proportion of length to breadth
  about 9 to 7. Roof bones coarsely sculptured posteriorly, finely
  sculptured anteriorly. Nasals and premaxillæ very large; frontals
  excluded from the orbits by junction of pre- and post-frontals.
  Pterygoids not meeting in the median line; parasphenoid dagger-shaped,
  tapering gradually to a point just in front of the palatine foramen;
  prevomers large. Orbits subcircular, situated in the posterior half
  of the skull; nares subovate, remote, at a considerable distance from
  the tip of the skull. Many minute denticles, on pterygoids, palatines,
  prevomers, and parasphenoid. Teeth circular in cross-section, strongly
  ribbed near the base, dentine strongly infolded. Three large teeth
  on each palatine. Mandible without postcotyloid process. Vertebræ
  rachitomous. Ribs double-headed. Pubis osseous. Three species
  (Permian), _E. megacephalus_, _E. latus_, and _E. willistoni_, are
  assigned to the genus.

Eryops is represented in the Carboniferous deposits of North America by
incomplete vertebral remains described by Case (94) from near Pittsburgh,
Pennsylvania.

[Illustration: MOODIE                                           PLATE 25

  1. Photograph of type specimen of _Erpetosaurus_ (_Tuditanus_)
       _radiatus_ Cope, from the Coal Measures of Linton, Ohio. × 1.3.
       Original in American Museum of Natural History.

  2. Photograph of type specimen of _Erpetosaurus tabulatus_ Cope,
       from the Coal Measures of Linton, Ohio. × 2. Original in the
       Zoological Collections of Columbia University.

  3. Photograph of the impression of _Stegops divaricata_ Cope, from
       the Coal Measures of Linton, Ohio. × 2. The specimen figured is
       in the American Museum of Natural History. Its obverse is in the
       collections at Walker Museum, University of Chicago.

  4. Type and only known specimen of _Micrerpeton caudatum_ Moodie,
       a branchiosaur from the Coal Measures shales of Mazon Creek,
       Illinois. × 2. Original in collections at Walker Museum,
       University of Chicago.

]


=Eryops sp. indet. Case, 1908.=

  Case, Annals Carnegie Mus., IV, p. 234, pl. 59, 1908.

A dorsal vertebra is very probably from this genus. The specimen consists
of a nearly perfect vertebra, lacking only the anterior zygapophysis and
the upper portion of the neural spine (plate 18, fig. 2). It shows no
character that would warrant its separation from the genus, and indicates
a medium-sized individual. The zygapophyses have clean-cut articular
faces. The pleurocentra are thickened above, with just well-defined
articular faces, which were applied to faces on the neural arch posterior
to the origin of the transverse process. The intercentrum is of the
familiar halfmoon-shape, thick and heavy below, and thinner toward the
extremities; the anterior edge is marked near the top by the indentation
found on the intercentra of _Eryops_.

Height of the vertebra from the middle of the lower face of the
intercentrum to the middle of the neural canal, 0.035 m.; width of
intercentrum 0.026 m.

The second recognizable specimen is a neural spine from the caudal series.
This is without question a portion of the skeleton of an Eryops. Similar
spines were described by Cope as _Eryops (Epicordylus) erythrolithicus_,
but later discoveries seem to show that similar characters occur in other
species of the genus as well. The apex of the spine is bifurcate; the
space between extremities is concave and perfectly smooth; below the sides
of the spine are rather rugose and marked with ridges. The lower portion
of the spine is elongated anteroposteriorly and the edges are marked with
sharp, double ridges.

Three ribs also belong, in all probability, to the genus _Eryops_. The
head of each rib is broad and the articular edge is divided between two
faces which meet at an angle somewhat greater than a right angle; the
two faces are continuous. The shaft is somewhat flattened and in the
undistorted specimens is gently curved. The length of the largest rib is
about 0.07 m.

Other than these specimens there are several small intercentra (94) and
the neural spine of a caudal vertebra from some undetermined amphibian.


=Family MACRERPETIDÆ Moodie, 1909.=

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 354, pl. lix,
    fig. 1, 1909.

It has seemed necessary to propose a new family for the reception of the
single species _Macrerpeton_ (_Tuditanus_) _huxleyi_ Cope. The characters
exhibited by this species are so different from those offered by other
members of the Carboniferous Microsauria that it is clearly distinct. In
its cranial characters and the position of the orbits it approaches most
nearly to _Eryops megacephalus_ Cope from the Permian of Texas. In some of
its characters the present form shows a similarity to _Dasyceps bucklandi_
Lloyd (324), from the Permian of Kenilworth, England; more especially is
this similarity found in the form of the skull, the size and shape of the
teeth, and the posterior position of the orbits, and their wide removal
from the border of the skull. Only a fragment of the skull has hitherto
been known, but repeated study of this fragment (123) has disclosed
the wide diversity (462) of its characters. An almost complete skull,
described below, substantiates the characters based on the fragment.
Another species is here added to the genus, based on a portion of a
mandible and a portion of the skull.

The family, Macrerpetidæ, may be defined (465) as follows:

  Skull larger than in any other known microsaurian, unless Baphetes
  proves to be microsaurian; cranial elements sculptured with pits and
  coarse grooves; lacrimal element present, teeth large, curved inwards
  and fluted; mandible heavy; orbits located far back on the skull and
  near the median line so that the interorbital space is about half the
  space from the outer edge of the orbit to the border of the skull,
  thus approaching the condition known in Eryops; the ribs (?) are
  strong, heavy, and curved, with an incipient tubercle.


=Genus MACRERPETON Moodie, 1909.=

  Moodie, Jour. Geol., XVII, No. 1, pp. 72-74, fig. 17, 1909.

Type: _Macrerpeton huxleyi_ Cope.

The genus _Macrerpeton_ was proposed for the reception of the amphibian
species described by Cope as _Tuditanus huxleyi_ (123). This form he
placed provisionally in genus _Tuditanus_, since it seemed to present the
same type of sculpturing of the cranial elements similar to that found
in _T. radiatus_ Cope. But this species has been removed from Tuditanus
and placed in a new genus, _Erpetosaurus_ (462). A close study of the
type specimen of _Tuditanus huxleyi_ Cope shows (465) great variation and
distinction from any of the species described from Linton, Ohio, or indeed
from any Carboniferous form thus far known.

The specimen represents the left side of the face, and the characters
exhibited by the fragment are supported by more complete material (No.
2933, Am. Mus. Nat. Hist.). The skull shows a close approach to the higher
labyrinthodonts in its shape. The orbits are far removed from the border
of the skull. The arrangement of the bones of the skull resembles that
of _Capitosaurus_ from the Keuper of Europe. The jaw is for the most
part slender, with a pronounced downward inflection at the coronoidal
part. The teeth are heavy and strong and are curved backwards. They
have the strong longitudinal fluting which is characteristic of the
labyrinthodonts. Another character which is distinctive is the pattern of
cranial sculpture. This consists of inosculating pits and grooves of a
coarse character and compares favorably with the sculpturing of Triassic
labyrinthodonts. If _Macrerpeton_ really represents a labyrinthodont form
of Amphibia it is the oldest of the known Labyrinthodontidæ, since it
seems probable that the _Eosaurus_ vertebræ came from a higher horizon.


=Macrerpeton huxleyi Cope, 1874.=

  Cope, Trans. Am. Phil. Soc., XV, p. 274, 1874.

  Cope, Geol. Surv. Ohio, II, pt. II, p. 397, pl. xxxiv, fig. 2, 1875.

  Lesley, Dictionary of Fossils, p. 1237, 1890.

  Moodie, Jour. Geol., XVII, No. 1, p. 72, fig. 17, 1909.

  Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 354, pl. lix,
    fig. 1, 1909.

Type: Specimen No. 119, American Museum of Natural History. Collection of
Dr. J. S. Newberry. (Plate 26, fig. 2.)

Horizon and locality: Linton, Ohio, Coal Measures.

[Illustration: MOODIE                                           PLATE 26

  1. Photograph of type specimen of _Erpetosaurus tuberculatus_
       Moodie, from the Ohio Coal Measures. × 1. Original in American
       Museum of Natural History.

  2. Photograph of type of _Macrerpeton huxleyi_ Cope, from the Ohio
       Coal Measures. × 1. Original in American Museum of Natural
       History.

]

The first part of the following account of the species, _Macrerpeton
huxleyi_ Cope, is a quotation of Cope's description (123) of the type
specimen, and the second part deals with the description of the new
material. Cope says the species is

  "Represented by a considerable portion of the face and muzzle of a
  single individual. A portion of the left mandible, supporting three
  teeth, remains in place, and almost the entire boundary of the right
  orbit is preserved.

  "The fragment indicates a much larger species than any other referred
  to the genus, and, next to the _Leptophractus obsoletus_, the largest
  of the Batrachians of the Ohio Coal Measures. Without more complete
  remains, it is not easy to determine its generic relations finally.

  "The form of the head is probably elongate, and the muzzle neither
  very obtuse nor elongate. The orbit is rather small, and near the
  middle of the length of the specimen, which is, however, incomplete at
  both ends. The sculpture of the surface of the head posterior to the
  orbits, as well as round their borders and for some distance in front
  of them, consists of a rather coarse pitting. On the middle line,
  between the orbits and on the muzzle, the intervals become narrower,
  and are confluent into transverse ridges or a delicate reticulation.
  The surface of the mandible displays a coarse reticulation.

  "The teeth are stoutly conic, and with delicately striate grooved
  cementum. They are slightly recurved.

  "This species differs from the _T. radiatus_ and _T. obtusus_ in the
  absence of the area into which the sculpture is thrown.

  "Longitudinal diameter of orbit, 19 mm.; length of alveolar border
  supporting three teeth, 13 mm.; diameter of base of tooth, 3 mm.;
  eight pits in 10 mm.

  "Dedicated to Professor T. H. Huxley, _facile princeps_ among English
  systematists, and an important contributor to the knowledge of the
  extinct Batrachia."

The following discussion of the cranial elements, based on the writer's
studies (462, 465) of the type, may be appended to Professor Cope's
original description. The sutures bounding a few of the elements have
been made out in part. The prefrontal element seems well assured. It lies
well in front of the orbit, much as in the skull of _Capitosaurus_ from the
Keuper of Europe. The lacrimal is, apparently, a very large bone, though
its entire extent is not assured.

The maxilla is a long, narrow element on the border of the skull. The
suture separating this from the lacrimal and jugal is quite clear. The
teeth which the maxilla undoubtedly bore are hidden by the remains of the
mandible, which lies partly on the edge of the skull. The jugal is a very
large element and its boundaries seem well assured. Its size and relations
recall the condition in Capitosaurus. It forms a part of the external
boundary of the orbit. The lateral suture of the postorbital is evident
and is, as shown in the figure, somewhat curved. The remaining elements
preserved on the fragmentary skull can not be accurately determined,
though their probable position is indicated in plate 30, fig. 2, the
lettering being based on the arrangement of these elements in Capitosaurus.

The lower jaw is poorly preserved, but what remains shows evidence of
being sculptured somewhat after the manner of the cranial elements. It
bore strong recurved teeth which are longitudinally striate.

Measurements of the Type Specimen of Macrerpeton huxleyi Cope.

                                mm.
  Length of portion preserved   120
  Maximum width of specimen      58
  Length of orbit                20
  Width of orbit                 14
  Length of jaw, as preserved    75
  Width of jaw at widest part    11
  Length of longest tooth         8
  Width of tooth at base          4


Description of Additional Material of Macrerpeton huxleyi.

The additional material of this species which has come to hand consists of
an almost complete skull (American Museum No. 2933, two portions); another
fragmentary skull (American Museum No. 8572 G and 8532 G); a portion of
an interclavicle (American Museum No. 8006); two incomplete vertebræ
(American Museum No. 8007); and another fragmentary element possibly
representing a scapula of this species (American Museum No. 8008).

The skull has essentially the shape outlined (462) from a study of the
fragmentary type specimen. The muzzle was drawn slightly too broad, but
otherwise the restoration is fairly accurate. The specimen is distorted
and imperfect, but enough is preserved to give a good idea of the shape
and something of the structure of the skull. A portion of the obverse is
preserved. The back part of the skull is broken, so that the occiput can
not be studied.

The length of the skull is one and two-fifths the greatest breadth (across
the orbits). The cranial elements are deeply marked with pits and short,
shallow grooves. On the left mandible these pits are in a very distinct
row, the _operculo-mandibular lateral-line_.


=Macrerpeton deani new species.=

Type: Specimen No. 2934, American Museum of Natural History.

Horizon and locality: Linton, Ohio, Coal Measures. (Plate 21, figs. 1, 2.)

The material for this species consists of the posterior half of the left
mandible and a portion of the right antero-lateral surface of the skull,
both incomplete. The reasons for regarding the species as distinct are the
large size of the specimens and the manner of the sculpture, as well as
the shape of the posterior end of the mandible.

[Illustration: Fig. 40. Mandible of Macrerpeton deani new species, from
Linton, Ohio. × 0.75.]

The present species is the largest amphibian of the Linton, Ohio, Coal
Measures, exceeding in skull length that of _Macrerpeton huxleyi_ by
twice. The largest skull of _Macrerpeton huxleyi_ which has so far
come under my notice is 120 mm. in median length. There are 3 skulls
of this species known, all of approximately the same size. The skull
of _Macrerpeton deani_ must have reached or exceeded a foot in median
length. The only species with which it can at all be compared are
_Eobaphetes kansensis_ Moodie and _Baphetes planiceps_ Owen, but it
is clearly distinct from all other genera of Linton Amphibia. It is
possible that when better known _Macrerpeton_, _Eobaphetes_, _Baphetes_,
_Erpetosaurus_, and possibly _Dendrerpeton_ will form a natural group of
early labyrinthodont-like Amphibia.

The mandible is similar in structure to that of the labyrinthodonts,
with the elements marked by radiate flutings. I can detect no evidences
of a lateral-line canal, such as is clearly marked in _Macrerpeton
huxleyi_ Cope by a series of rounded pits, occupying the usual position
of the operculo-mandibular lateral-line canal The teeth, of which 6 are
preserved, are minutely striate, with smooth apices. They are dissimilar
in size, showing a variation of 2 or 3 mm. in length.

The sculpture is a coarse fluting, with no indications of the sharply
marked pits of _Macrerpeton huxleyi_ Cope.

The fragment of a skull preserved shows characters of the sculpture which
are identical with those of the mandible. The bones are so crushed that it
is impossible to tell the limits of the elements. I believe a portion of
one orbit is represented on one corner of the block. The cranium appears
to have been broad, and the fragment preserved, which is only about
one-sixth of the skull, is larger than the entire cranium and mandibles of
_Macrerpeton huxleyi_.

The specific distinctness of the form can not be doubted, although it is a
matter of regret that it is founded on so small a portion of the osteology
of the animal.

The species is proposed in honor of Dr. Bashford Dean, to whom I am
greatly indebted for many kindnesses during the past 5 years in connection
with my studies on Carboniferous Amphibia, particularly in the loan of the
entire Newberry collection of Linton, Ohio, Amphibia.

Measurements of the Type of Macrerpeton deani Moodie.

                                                      mm.
  Length of portion preserved                         115
  Greatest width                                       50
  Length of tooth                                       9
  Width at base                                         4
  Length of angular                                    95
  Diameter of angular                                  25
  Measurements of specimen No. 8535 G, American Museum
    of Natural History, associated with the above in
    the type description:
      Length of preserved portion                     140
      Diameter of orbit                                22


=Family ANTHRACOSAURIDÆ Cope, 1875.=

  Cope, Bull. U. S. Nat. Mus., I, p. 10, 1875.

  Lydekker, R., 1890, Cat. Fossil Reptilia and Amphibia, p. 157.

  Skull usually triangular and more or less angulated, with the cranial
  sculpture well marked, the occipital condyles ossified, and the
  palatine foramina very small and placed far back; dentine of the
  teeth more or less complexly plicated. A ventral armor of elongated
  dermal scutes, and probably a sclerotic ring. Bodies of vertebræ fully
  ossified in the adult; intercentra present or absent. According to
  Atthey's figure (11) of the skull of the type genus, the palatine
  bears teeth which are situated immediately on the inner side of the
  maxilla, as in Mastodonsaurus (242). In the typical forms there is no
  postarticular process to the mandible.

The North American species of this family are: _Eosaurus acadianus_
Marsh, _Eobaphetes kansensis_ Moodie, _Dendrerpeton acadianum_ Owen,
_Dendrerpeton oweni_ Dawson, _Platystegos loricatum_ Dawson, _Baphetes
planiceps_ Owen, _Baphetes minor_ Dawson.

There is but little assurance that any of these species belong in this
family. They are put there provisionally, pending future discoveries.
Huxley suggests the relationship of _Eosaurus_ and _Anthracosaurus_
(Quart. Jour. Geol. Soc., XIX, 1863, p. 65; Scientific Memoirs, II, p.
566).


=Genus BAPHETES Owen, 1854.=

  Owen, Quart. Jour. Geol. Soc. London, X, p. 207, pl. ix, 1854.

  Dawson, Air-breathers of the Coal Period, pp. 10-16, pl. ii, 1863.

Type: _Baphetes planiceps_ Owen.

Known only from an incomplete skull, which is large, broader than long;
squamosals prolonged into obtuse horns. Teeth rather large, heterodont,
arranged in a single row. Orbits placed well forward, frontals small,
surface bones sculptured.


=Baphetes planiceps Owen.=

  Owen, Quart. Jour. Geol. Soc. London, X, p. 207, pl. ix, 1854.

  Dawson, Air-breathers of the Coal Period, pp. 10-16, pl. ii, 1863.

Type: Specimen in the British Museum of Natural History.

Horizon and locality: Near Pictou, Nova Scotia (Coal Measures).

The parts preserved include the premaxillaries, nasals, and portions of
the frontal, prefrontal, and maxillary bones. The fossil is embedded
in a mass of Pictou Coal from Nova Scotia and consists of the anterior
extremity of the cranium (plate 22, fig. 6) and with the exterior surface
of the bone embedded in the matrix, and its substance, for the most
part, reduced to a thin layer by abrasion of the exposed inner layer. It
displays accurately the contour of the fore part of the upper jaw, which
was broad, obtuse, and rounded.

The premaxillaries, which show some obscure traces of a symphysial suture
at the median line, anterior to the nasal or naso-palatine vacuities,
extend outwards, on each side, for an extent of 2.5 lines and there
join the maxillaries. Traces of round alveoli for teeth, some of which
are 2 lines in diameter, are visible on the alveolar border of the
premaxillaries. The alveolar border is continued by the maxillary bone for
an extent of 4.5 inches beyond the premaxillary border, and this border
shows still more distinct traces of alveoli, of a circular form, about a
line in diameter and rather close set in a single series. The fore part
of the orbit is very unequivocally displayed, the smooth inner or under
surface of the bone forming that part being entire; and this shows the
fore part of the orbit to be formed, partly by the maxillary, partly
by the lacrimal or prefrontal bone in close sutural union therewith,
a structure which does not exist in any recent or fossil fish with a
dentigerous superior maxillary bone. Where the substance of the bone has
been detached so far as to expose the external layer in contact with
the coal, as, _e.g._, on the frontal and part of the prefrontal bones,
the external surface of those bones is shown to have been impressed by
subhemispherical or elliptical pits, from 1 line to 1.5 lines in diameter,
and with intervals of half of that extent. This coarsely pitted character
agrees with that presented by the other surface of the similarly broad and
flat cranium of the labyrinthodonts.

From the characters above specified, therefore, I conclude that this
fossil is the fore part of the skull of an extinct family of the
labyrinthodonts. It agrees with them in the number, size, and disposition
of teeth; in the proportions and mode of connection of the premaxillaries,
maxillaries, nasals, prefrontals, and frontals, and in the resultant
peculiarly broad and depressed character of the skull. The traces of
the nostrils are less definite and satisfactory than the remains of the
orbits, but the latter appear to be decisive against the piscine nature
of the fossil. The fossil also presents the same well-marked external
sculpturing as in the labyrinthodonts; and among the genera that have
been established in that family, the form of the end of the muzzle, or
upper jaw, in the Pictou coal specimen best accords with that in the
_Capitosaurus_ and _Metopias_ of von Meyer and Burmeister (80).

Measurements of the Skull of Baphetes planiceps Owen.

(Type in the British Museum of Natural History, London.)

                                         mm.
  Approximate median length of skull     136
  Width of skull across base of horns    150
  Estimated width across tips of horns   186
  Width of horn at base                   31
  Estimated length of horn from base      80
  Width of skull across orbits            97
  Diameter of orbit                       21
  Diameter of large tooth alveolus         7
  Diameter of small tooth alveolus         2

Pictou Coal, near Pictou, Nova Scotia, Canada, collected by Dr. J. William
Dawson, 1850, and presented by him to the Geological Society of London.


=Baphetes minor Dawson.=

  Dawson, Canadian Nat. and Jour. Sci., n. s., 1870, V, pp. 98, 99.

Type: Specimen in the Peter Redpath Museum, McGill University.

Horizon and locality: Coal formation of Nova Scotia.

The species was based on a lower jaw of an amphibian, of which a cast had
occurred in the coarse sandstone of the coal formation between Ragged Reef
and the Joggins Coal Mine. It measured 6 inches in length; its surface
was marked on the lower and posterior part with a network of ridges
inclosing rounded depressions. The anterior part of the jaw contained
about 16 teeth, some of which remained in the matrix. These were stout,
conical and blunt, with large pulp cavities, and about 32 longitudinal
striæ, corresponding to the folds of the dentine. Dawson states that this
jaw resembles most closely those of _Baphetes_ and _Dendrerpeton_, but more
especially the former. He regarded it as distinct from _Baphetes planiceps_,
and proposed for it the name _Baphetes minor_.


=Eosaurus acadianus Marsh.=

  Marsh, Am. Jour. Sci. (2), XXXIV, pp. 1-16, pls. i, ii, 1862.

  Agassiz, Am. Jour. Sci., XXXIII, p. 138, 1862.

  Marsh, Quart. Jour. Geol. Soc., XIX, pp. 52-56.

  Hay, Cat. Fossil Vertebrates (Bull. U. S. Geol. Surv. No. 179, p. 421,
    1902).

Type: Specimen No. 1648, Yale University Museum.

Horizon and locality: South Joggins, Nova Scotia (Coal Measures).

The genus and species are founded on two vertebral bodies of the
stereospondylous type from the Coal Measures of the South Joggins, Nova
Scotia. Marsh's description (404) is as follows:

  "The general form of the vertebræ is cylindrical, but their sides
  are compressed obliquely, which gives to the contour of the centra a
  subhexagonal appearance. They are much flattened in the direction of
  the antero-posterior diameter, which has to the transverse diameter
  the proportion of 1 to 3. Both the articular terminal facets are
  deeply and equally concave; but from the center to the margin the
  surfaces are convex, and this convexity is greatest near the center.
  * * * The cavities for the reception of the intervertebral matter
  begin immediately from the margin, and are considerably deeper
  than the corresponding parts of the _Ichthyosaurus_, indicating a
  greater degree of flexibility in the vertebral column. The margins
  of the vertebra; are somewhat raised, as if they had yielded to a
  forcible compression applied longitudinally; and hence the lateral
  surfaces of the centers are concave in an antero-posterior direction.
  This concavity is greater in the upper half of the vertebra and
  was undoubtedly more marked originally than at present, since the
  appearance of the margins indicates considerable abrasion. The
  non-articular surfaces of the centra are smooth and regular; and the
  external fibres of the osseous tissue are singularly reticulated.

[Illustration: Fig. 41. Nova Scotian Amphibia.

  A. Oblique lateral view of vertebra: of _Eosaurus acadianus_ Marsh,
       _a_, pits for articulation of neuropophyses; _b_, rudimentary
       transverse process on right lateral surface of centrum.

  B. Oblique view of vertebræ, _a_, pits for articulation of
       neuropophyses; _b_, rudimentary process on lateral surface.

  C. Posterior view of nearly perfect centrum.

  D. Transverse section of same vertebra, showing deep concavities of
       articular terminal facets.

  E and F. Microscopic sections near surface, showing lacunæ arranged
       around an Haversian canal. Magnified 200 diameters.

  (All figures after Marsh. × 0.75.)

]

  "The neuropophyses are not anchylosed to the centrum, as in the
  mammalia, nor connected to it by sutures, as in the crocodiles;
  but their union with the vertebra is indicated by two pits, which
  served for their articulating surfaces. These depressions are
  situated on the superior surface of the centrum intermediate between
  the anterior and posterior margins of the extremities. They are
  circular in form and sink directly into the body of the vertebra;
  instead of being elongated longitudinally and raised by ridges, as
  in _Ichthyosaurus_. The pits are about a line in depth, and in the
  more perfect of the fossils are not in their original position. The
  floor of the spinal canal is narrow, being but 5 lines in breadth. A
  rudimentary transverse process, or exogenous tubercle, is sent off
  from each lateral surface of the centrum, at points equidistant from
  the extremities of the vertical diameter. Their position is near the
  margin of the anterior articular surface, and the edges of these
  parapophyses make the transverse diameter of this extremity somewhat
  greater than that of the corresponding posterior facet."

Measurements of the More Perfect Vertebra of Eosaurus acadianus (after
Marsh).

                                                      mm.
  Transverse diameter of centrum on anterior surface  59
  Same on posterior surface                           57
  Same including the parapophyses                     63
  Vertical diameter of anterior surface               54
  Anteroposterior diameter on superior surface        21
  Same on inferior surface                            19
  Same between centers of articular facets             2.5
  Length of pits for articulation of neural arch       7
  Breadth of same                                      7
  Depth of same                                        2
  Distance between centers of same                    11
  Same at centers of parapophyses                     36

Collected by O. C. Marsh at the South Joggins, Nova Scotia.

Marsh regarded (404) the vertebræ as representing a new type of
ichthyosaurian (2), but there can be no doubt that the vertebræ belong
to some form of the Amphibia, since the description applies equally well
to them. In this connection mention must be made of a large rib from the
Linton beds preserved in the U. S. National Museum. Only the proximal
third of the rib is preserved, but it represents some large form of the
Stegocephala. The rib is strongly curved backward, is heavy, and has an
incipient tubercle. A cross-section shows that a longitudinal groove
occupies the median line on the exposed surface of the rib. This may,
however, be due to compression and thus indicate that the rib was hollow.
The rib as preserved measures: length, 102 mm.; maximum width, 22 mm.;
minimum width, 14 mm. (Nos. 4490, 4489, U. S. National Museum.)


=Genus EOBAPHETES new name.=

Type: _Eobaphetes kansensis_ Moodie.

The new name is proposed to replace the generic term _Erpetosaurus_ used
for the species _E. kansensis_ described by the writer (Proc. U. S. Nat.
Mus., 39, p. 491, 1911), and which later was found to be preoccupied by
Newton (Phil. Trans. Roy. Soc. London, 185, p. 573, 1894 B).

The genus is very readily distinguished by two prominent characters the
short, uniform dentition and the presence of two elongate, oval, internal
mandibular foramina on the inner side of the jaw. The genus may be further
distinguished by the great depth of the posterior portion of the jaw and
the slender anterior part, as well as by the ornamentation, which is
typically the rough tuberculated labyrinthodont sculpture on the anterior
end of the mandible. This changes gradually to longitudinal grooves and
ridges of a rather small size on the posterior portion, a very unusual
arrangement for a labyrinthodont.

These characters are sustained by those of the skull fragment, in
which the dentition is uniform and the sculpture very similar to that
of the mandible. The ribs are long, curved, and solid, as in other
labyrinthodonts.

The internal surface of the mandible shows much similarity to that of the
crocodiles and alligators of the present day. The resemblance is not due
to homology of structures, but must be regarded as a parallel development
of similar characters.


=Eobaphetes kansensis Moodie.=

  Moodie, Proc. U. S. Nat. Mus., 39, pp. 491-494, figs. 1 to 3, 1911
    (_Erpetosuchus_).

Type: Specimen No. 6699, U. S. National Museum.

Horizon and locality: Coal Measures of Washington County, Kansas.

The species is represented in the collections of the U. S. National Museum
by a fragment of the skull, with portions of two ribs (Cat. No. 6699,
Vert. Pal. U. S. Nat. Mus.) and the larger part of the left ramus of the
mandible (Cat. No. 6680, Vert. Pal. U. S. Nat. Mus.). The mandible was
preserved in a large block of coal which contained the impression of the
back portion of the mandible from which the bone had been weathered. It
was possible to remove the bone and make a plaster cast of the impression.
This shows in a very satisfactory manner all of the characters of the
external surface.

_Skull._--Only a portion of the left maxilla, with 14 teeth, and a part of
the nasal are preserved. The skull seems to have been laterally crushed
and the right side of the skull has been crushed flat under the left. It
has not seemed feasible to remove the skull from the matrix.

The teeth are uniform, rather short, bluntly conical, curved backward, and
coarsely striate. They are somewhat crowded, the bases being separated
from each other by only a fraction of a millimeter.

The maxilla and portion of the nasal are coarsely sculptured with elongate
pits and ridges. A portion of the infraorbital lateral-line canal is
preserved. It is simply a rounded groove with three short branches. It
lies near the middle of the maxilla.

_Mandible._--It has been possible to study both sides of the mandible.
The left ramus was preserved in the coal, with its inner face exposed.
This face is broken by two large oval openings, the internal mandibular
foramina. This is the term used by Reynolds for the openings on the inner
surface of the alligator jaw. So far as I can ascertain, no other known
labyrinthodont mandible displays this character in such a marked degree.
Dr. Branson has figured in _Anaschisma browni_ Branson from the Triassic
(49) of Wyoming the inner surface of the left ramus, on which there are
likewise two openings but differently situated. A similarity between the
two mandibles is observed in that the suture separating the prearticular
and angular touches the posterior edge of the posterior foramen.

Several of the sutures are well preserved and they have been indicated
in the drawing (fig. 42). The pillar separating the two foramina is cut
by the suture separating the angular and prearticular very much as in
_Anaschisma_, with the difference that in the latter form the angular
and prearticular are not approximated. I believe I detect the suture as
represented separating the anterior end of the angular from the dentary
and splenial. I am assured of the portion near the anterior foramen and
also of the part near the tip of the ramus. This shows the angular to be
a very elongate element, running very nearly the entire length of the
mandible, much as in _Anaschisma_ and other labyrinthodont genera. The
splenial is a small, slender element located farther forward, where it
has been shoved by the large-sized internal mandibular foramina. The
prearticular is a rather long, broad element, of which only a portion is
preserved. I am not sure as to the location of the suture for the dentary,
unless it is represented by the line bounding the roughened area near the
teeth. If this is true, the dentary is a large element, since it extends
well down upon the outer side of the jaw. The dentary possesses evidences
of 26 teeth, a few of which are completely preserved. Most of them are,
however, represented either by bases or by impressions in the coal. The
teeth are very similar to those of the maxilla, though slightly larger.
The characters given for the maxillary teeth will suffice for those of the
dentary.

[Illustration: Fig. 42.

  A. Outer view of mandible of _Eobaphetes kansensis_ Moodie, from
       the Coal Measures of Washington County, Kansas. Original in U.
       S. National Museum. × 0.33. Cat. No. 6680. _a_, angular; _r_,
       articular; _d_, dentary.

  B. Portion of skull of _Eobaphetes kansensis_ Moodie, from the Coal
       Measures of Washington County, Kansas. Original in U. S. National
       Museum. Cat. No. 6699. × 0.33. Lateral-line canal represented by
       heavy broken line, _n_, nasal; _m_, maxilla.

  C. Inner surface of mandible of _Eobaphetes kansensis_ Moodie, from
       the Coal Measures of Washington County, Kansas. × 0.33. _a_,
       angular; _p_, prearticular; _r_, articular; _s_, splenial.

]

The markings of the inner surface are as indicated in the drawing. The
back portion of the angular shows a few radiating lines. The dentary is
roughened in two portions: one near the teeth, the other at the tip, where
there is a cartilaginous roughening for union with its mate. The remainder
of the inner surface is relatively smooth.

The outer surface shows at the anterior end the typical labyrinthodont
sculpturing, which becomes slight grooves and ridges posteriorly. I detect
evidences of the operculo-mandibular lateral-line canal throughout the
entire length of the mandible. Its location is indicated by the heavy
broken line. The suture between the dentary and angular is quite clear.
The suture separating the dentary and splenial joins the angular suture
about midway of the length of the jaw.

Measurements of Skull Fragment of Eobaphetes kansensis Moodie.

(Cat. No. 6699, U. S. Nat. Mus.)

                                      mm.
  Total length of portion preserved   109
  Maximum width of maxilla             45
  Thickness of maxilla                  7
  Length of tooth                      10
  Width of tooth at base                4

Measurements of Left Ramus of Mandible of Eobaphetes kansensis Moodie.
(Cat. No. 6680, U. S. Nat. Mas.)

                                                    mm.
  Total length of jaw, as preserved                 305
  Greatest width                                     79
  Least width                                        24
  Length of angular                                 132
  Width of angular                                   45
  Length of largest tooth                            10
  Width of largest tooth at base                      6
  Length of most posterior tooth                      6
  Width of most posterior tooth at base               4
  Length of anterior internal mandibular foramen     56
  Greatest width                                     15
  Least width                                         7
  Length of posterior internal mandibular foramen    77
  Greatest width                                     28
  Least width                                        14
  Length of bridge                                   16
  Width of bridge                                     8

_Ribs._--There are portions of two dorsal ribs preserved on the block of
coal with the skull. These show characters very similar to those exhibited
by the rib ascribed to _Macrerpeton huxleyi_ Cope, and also those of
_Metoposaurus diagnosticus_ von Meyer (242) and _Anaschisma_. The ribs
are solid, heavy, curved, and have a longitudinal groove on the middle of
each side. The heads of the ribs in the present specimen are obscured and
nothing can be said of them except that they appear to be large.

Measurements of Ribs of Eobaphetes kansensis Moodie.

                                      mm.
  Length of preserved portion         130
  Width at distal end                  18
  Thickness of rib                      5


=Genus DENDRERPETON Owen, 1853.=

  Owen, Quart. Jour. Geol. Soc. London, IX, p. 66, 1853.

Type: _Dendrerpeton acadianum_ Owen.

The genus is characterized by Dawson as follows (Phil. Trans., 1882, p.
635):

  "Lizard-like, with anterior and posterior extremities nearly equal;
  the skull somewhat elongate with small orbits, and the nostrils placed
  at the front. The cranial bones sculptured. The teeth plicated at the
  base, more especially on their inner sides. A series of large teeth on
  the palate. The body was covered above with imbricated horny scales
  and had lappets or pendants at the sides. The abdomen was protected by
  thin bony scales semi-elliptical or oat-shaped in form, and arranged
  in a chevron pattern. There was probably also a thoracic plate. Two
  species: _D. acadianum_ and _D. oweni_.

"Type: _D. acadianum_ Owen."


=Dendrerpeton acadianum Owen.=

  Owen, Quart. Jour. Geol. Soc. London, IX, p. 66, 1853.

  Dawson, Air-breathers of the Coal Period, p. 17, 1863.

  Dawson, Acadian Geology, 3d ed., p. 362.

  Dawson, Phil. Trans. Roy. Soc. London, pt. II, p. 642, pl. 40, figs.
    46 to 51; pl. 44, figs. 129 to 137. 1882.

Type: Specimens Nos. 434-438, British Museum of Natural History. Horizon
and locality: Coal formation at South Joggins, Nova Scotia. (Plate 6.)
This species has been fully described and figured by Dawson (Air-breathers
of the Coal Period, pp. 17-30, pl. III, figs. 1 to 30, 1863), who gives
a detailed account of the discovery of the material of this species by
himself and Sir Charles Lyell. He says, in part:

  "In form, _Dendrerpeton acadianum_ was probably lizard-like; with a
  broad flat head, short, stout limbs and an elongated tail; and having
  its skin, and more particularly that of the belly, protected by small
  bony plates closely overlapping each other. It may have attained
  the length of 2 feet. The form of the head is not unlike that of
  _Baphetes_, but longer in proportion; and much resembles that of the
  labyrinthodont reptiles of the Trias. The bones of the skull are
  sculptured as in _Baphetes_, but in a smaller pattern. The nostrils
  are small, and near the muzzle; the orbits are circular, and separated
  by a space of more than their own diameter. In the upper jaw there is
  a series of conical teeth on the maxillary and intermaxillary bones.
  Those on the intermaxillaries are much larger than the others, and
  have the aspect of canines or tusks. Within this outer series of
  teeth, but implanted apparently in the same bones, there is as in
  _Archegosaurus_ a second series of teeth, closely placed, or with
  intervals equal to the diameter of one tooth. These inner teeth are
  longer than the others, implanted in shallow sockets, to which they
  are anchylosed, and have the dentine plicated, except toward the
  point. A third group of teeth, blunt at the points, largely hollow in
  the interior, and with the dentine quite simple, appears in detached
  bones, which may represent the vomer. Only a part of this formidable
  armature of the teeth appears in the skull, as the bones of the roof
  of the mouth have been removed, adhering to the opposite side of
  the matrix; but the fact of the occurrence of two sets of teeth was
  ascertained by Professor Wyman, from the original specimens, and is
  manifest in the fragment * * * while the other teeth, supposed to
  be vomerine, appear in fragments which must, from their size and
  collocation, have belonged to _Dendrerpeton_. It will be observed
  that all of these teeth are anchylosed to the bone; and that those
  of the vomer are thinly walled and simple, the outer series on the
  maxillaries and intermaxillaries simple and flattened, while the inner
  series of teeth are conical and plicated. In the lower jaw there was
  a uniform series of conical teeth, not perceptibly enlarged toward
  the front; at least this is the case in the only specimen at present
  in my collection; which is, however, merely an imperfect cast in hard
  sandstone.

  "The scapular and sternal bones seem to have been well developed and
  strong, but only portions of them are known. The fore limb of the
  adult animal, including the toes, must have been 4 or 5 inches in
  length, and is of massive proportions. The bones are hollow, and in
  the case of the phalanges the bony walls were thin, so that they are
  often found crushed flat. The humerus, however, was a strong bone,
  with thick walls and a cancellated structure toward its extremities;
  still, even these have sometimes yielded to the great pressure to
  which they have been subjected. The cavity of the interior of the
  limb-bones is usually filled with calc-spar stained with organic
  matter, but showing no structure; and the inner side of the bony wall
  is smooth, without any indications of cartilaginous matter lining it.

  "The vertebræ, in the external aspect of their bodies, remind one of
  those of fishes, expanding toward the extremities, and being deeply
  hollowed by conical cavities, which appear even to meet in the center.
  There is, however, a large and flattened neural spine. The vertebræ
  are usually much crushed, and it is almost impossible to disengage
  them from the stone. * * * in its long neural and hæmal spines,
  reminds us of the caudal vertebræ of those batrachians and reptiles
  which have tails flattened for swimming, and probably indicates that
  this was the case with _Dendrerpeton_. The ribs are long and curved,
  with an expanded head, near to which they are solid, but become
  hollow toward the middle; and the distal extremities are flattened
  and thin-walled. The posterior seems to have been not larger than
  the anterior, perhaps smaller. The tibia is much flattened at the
  extremity, as in some labyrinthodonts, and the foot must have been
  broad, and probably suited for swimming or walking on soft mud, or
  both. That the hind limb was adapted for walking is shown not merely
  by the form of the bones, but also by that of the pelvis, the best
  preserved specimen of which I have represented (208, pl. III, fig. 28).

  "The external scales are thin, oblique-rhomboidal or elongated-oval,
  marked with slight concentric lines, but otherwise smooth, and
  having a thickened ridge or margin; in which they resemble those
  of _Archegosaurus_, and also those of _Pholidogaster_. * * * The
  microscopic structure of the scales is quite similar to that of the
  other bones, and different from that of the scales of ganoid fishes
  * * * ." #/


=Dendrerpeton oweni Dawson.=

  Dawson, Quart. Jour. Geol. Soc. London, XVIII, p. 460.

  Dawson, Air-breathers of the Coal Period, p. 32, 1863.

  Dawson, Acadian Geology, 3d ed., p. 368.

  Dawson, Phil. Trans. Roy. Soc. London, pt. II, p. 643, pl. 44, figs.
    131, 138, 139, 1882.

A smaller species than the preceding. The form (plate 13) is fully
described by Dawson (Air-breathers of the Coal Period, p. 32, pl. IV,
1863) as follows:

  "Among the reptilian remains found in erect trees at the South
  Joggins, there have occurred several portions of skeletons which, from
  their sculptural cranial bones, plicated teeth, and the forms of their
  scales and limb-bones, I have referred to the genus _Dendrerpeton_,
  but to individuals of much smaller size than the full-grown specimens
  of _D. acadianum_. It did not occur to me to suppose that these were
  specifically distinct from the larger individuals, until I observed
  that bones of this kind, contained in the collections sent by me
  to the Geological Society, or represented in the figures drawn to
  illustrate one of my papers, were referred by Professor Owen, in his
  notes on these specimens and figures, in the Journal of the Geological
  Society, to the genus _Hylonomus_; which is quite distinct from
  _Dendrerpeton_, as will be explained in sequel.

  "I was thus induced to reexamine all the specimens in my collection
  and the result has been to establish a strong probability that there
  is in reality a second species of Dendrerpeton, smaller than _D.
  acadianum_, and differing from it in several points. This species I
  propose to name _D. oweni_. It differs from _D. acadianum_ in the
  following particulars: (i) its much smaller size; (2) its long and
  hooked teeth (it will be seen that these teeth differ very markedly
  in their proportions and form from those of the larger species);(3)
  the greater plication of the ivory in the intermaxillary teeth (in
  _D. acadianum_ these teeth are, on the outside, simple almost to the
  base, and plicated on the inner side, while in this species they are
  plicated all around like the inner maxillary teeth);(4) the form of
  the skull, which has the orbits larger in proportion, and is also
  shorter and broader. On the other hand, when we have described the
  species Hylonomus, it will be seen that this animal, except in size,
  differs from them quite as widely as does _D. acadianum_.

  "The distinctness of _D. oweni_ is further confirmed by the fact that
  I possess small jaw-bones of _Dendrerpeton_, about the size of those
  of this species, but having the teeth similar in form to those of the
  larger species; these I suppose to have belonged to young individuals.

  "On examining the figures (208, pl. IV) it will be seen that the
  bones of the skull were corrugated as in the large _Dendrerpeton_,
  but with a smaller pattern. The forms of the jaw-bones also, and
  of the vertebræ, ribs, scapular bone, bones of the limbs, and bony
  scales, are very similar, and indicate that in general form this
  creature was not far removed from its larger relative. The bones
  of the foot especially deserve attention. This is the most perfect
  foot of _Dendrerpeton_ hitherto found; and I have enlarged it in the
  figure (208) in order more distinctly to show its parts. It presents
  three long toes with traces of a smaller one at each side, so that
  there were probably five in all. If these toes be compared with the
  footprints on the slab discovered by Dr. Harding, it will be seen that
  they very closely correspond, though the toes of the present species
  are much smaller. The footprints are precisely those which we may
  suppose an animal of the size of _Dendrerpeton acadianum_ would have
  made if, as the bones found render in every way probable, this larger
  species had a foot similar to that of _D. oweni_. I suppose, for
  this reason, that these footprints are really those of Dendrerpeton
  acadianum and that this species continued to exist from the time of
  the lower Coal Measures to the period when those higher beds of the
  series, in which its bones are found at the Joggins, were deposited.

  "The present species must have lived in the same places with its
  larger relative, but may have differed somewhat in its habits. Its
  longer and sharper teeth may have been better suited for devouring
  worms, larvæ, or soft-skinned fishes, while those of the larger
  _Dendrerpeton_ were better adapted to deal with the mailed ganoids of
  the period, or with those smaller reptiles which were more or less
  protected with bony or horny scales.


REMAINS OF SKIN AND HORNY SCALES.

  "In one of my earliest explorations of the reptile-bearing stumps of
  the Joggins, I observed on some of the surfaces patches of a shining
  black substance, which on minute examination proved to be the remains
  of cuticle, with horny scales and other appendages. The fragments
  were preserved; but I found it impossible to determine with certainty
  to which of the species whose bones occur with them they belonged,
  or even to ascertain the precise relations of the several fragments
  to each other. I therefore merely mentioned them in general terms,
  and stated my belief that they may have belonged to the species of
  _Hylonomus_.[E] More recently other specimens have been obtained, and
  I have undertaken the detailed examination of the whole. I shall now
  endeavor to describe the principal or most continuous fragments, and
  afterward to consider the probabilities of their having belonged to
  certain of the reptiles entombed with them. I do this here, rather
  than under the titles of these several animals, on account of the
  uncertainty which still rests on the assignment of certain portions
  of this cuticle to the species in question, and which renders it more
  convenient to consider these peculiar remains in one place and to
  compare the different portions with each other.

[Footnote E: Journal of Geological Society, vol. XVI.]

  "(1) One of my specimens is a flattened portion of cuticle 2.25
  inches in length. The greater part of the surface is smooth and
  shining to the naked eye, and under the microscope shows only a
  minute granulation. A limited portion of the upper and, I suppose,
  anterior part is covered with imbricated scales, which must have been
  membranous or horny and generally have a small spot or pore near the
  outer margin, some having in addition smaller scales or points on
  their surfaces. In contact with the upper part of this specimen there
  were many fragments of the skull of _Dendrerpeton oweni_.

  "(2) Another portion of the cuticle, similarly marked, appears to
  preserve the form of the posterior part of the body and tail of the
  animal, and also a mark representing the point of attachment of the
  hind leg; near to which, and along the dorsal ridge, is a portion of
  the skin covered with much smaller scales. This was found in close
  proximity to a mass of bones of Dendrerpeton oweni, mingled with some
  of _Hylonomus lyelli_.

  "(3) A third and still larger surface of integument with similar
  markings has upon it a number of vertebræ and detached bones of the
  small reptile _Hylonomus wymani_, to be described in the sequel; for
  which species, however, it would be much too large a covering.

  "(4) Another well-preserved fragment, less than 2 inches in length,
  exhibits very different markings. It is nearly covered with very small
  imbricated scales, thicker than those on the specimens previously
  described. On either side of what seems to have been the middle line
  of the back, there is a series of pointed flat horny processes, which
  probably formed a double spinous crest. Without these there are tufts
  of strong bristles, and exteriorly to these last are rows of flat,
  thick, horny plates, transversely wrinkled. Near to these was a row of
  conical truncated tubercles. Sections of these appendages show them to
  have been horny and attached to the cuticle. None of them have bony
  structure.

  "(5) Near this last portion of cuticle, and possibly belonging to
  it, are pointed and probably membranous appendages, marked on each
  side with rows of scales not overlapping and each with a pore in its
  center. The manner in which these appendages are bent and wrinkled
  shows that they must have been soft, except at the tips, which seem
  to have been hard and horny, and they are arranged in series, as if
  originally placed along the sides of the neck or abdomen, or both.
  The use of these appendages is not easy to conjecture. They remind
  us of the gular pouches of iguana, and of the lateral expansions of
  some geckos and of the _Draco volans_. Possibly they formed lateral
  parachutes, aiding the animal in moving over soft mud, or perhaps in
  leaping and swimming.

  "(6) Some other fragments appear to have belonged to a different
  species from either of the foregoing. The best preserved specimen,
  which is about 1 inch in length and half an inch in breadth, is
  covered with very small imbricated scales. It is crossed by 6 or 7
  obscure ridges, which both at the bottom and along a mesial line
  project into points covered with larger scales. A row of large scales
  with round pores connects these along the lower side. If, as seems
  probable, this fragment belonged to the side of the trunk or tail,
  it would perhaps indicate a division of the subcutaneous muscles
  into an upper and lower band, as in the newts. A separate fragment
  with transverse horny ridges and another with a longer lobe, similar
  in structure to those above mentioned, may perhaps be referred to
  the same animal. A larger patch of skin presents similar imbricated
  scales, but without a mesial line, and with an edging of larger scales.

  "Six species of reptiles have left their bones in the repositories
  containing these remnants of cuticle. Of these, _Dendrerpeton
  acadianum_, was an animal of too great size to have been clothed
  with integument of this character and of such dimensions. Hylonomus
  aciedentatus and _Hylerpeton dawsoni_ are each represented by only a
  single specimen, and these did not occur in proximity to any of the
  portions of cuticle, except that the appendages were found near a
  specimen of the former. Of the three remaining species, _Dendrerpeton
  oweni_, from its size, the number of specimens found, and the
  juxtaposition of their bones to the fragments of cuticle, appears to
  have the best claim to the integument included under Nos. 1, 2, and
  3; and in this case, while the creature had its throat, and perhaps
  its abdomen, armed with bony scales, its upper parts and tail, as well
  as its limbs, had a uniform covering of small, thin imbricated horny
  scales, in the manner of many modern reptiles.

  "If the remaining portions of integument, Nos. 4 and 5, as would
  seem likely, belonged to two species, both of smaller dimensions,
  there would seem little reason to doubt that these were _Hylonomus
  lyelli_ and _H. wymani_. In this case, both of these species must have
  possessed a highly ornate covering of horny scales and appendages,
  comparable with that of many of the modern lizards, while there
  seems good reason to believe, as stated in a previous paper, that
  they were in part protected by bony scales somewhat like those of
  _Dendrerpeton_. These points, however, we shall consider more in
  detail under the sections which refer to the species of _Hylonomus_.

  "Before leaving these curious specimens of ancient skin, the most
  ancient I suppose known to exist, it is of interest to observe that
  the thicker portions, when broken across, have the aspect of jet, or
  of pure shining coal, and thin slices, under the microscope, have
  the same rich brown colour with that material, though rather more
  translucent. When burned, fragments of the substance give a strong
  flame, and a bituminous and ammoniacal odour. We have thus an example
  of the production of coal from animal membrane, no doubt gelatinous
  and horny in the first instance, but which has proved itself capable
  of the same chemical changes that have been experienced by the
  vegetable matter buried with it. In order that this substance should
  be preserved in this way, it would be necessary that it should either
  be kept dry and hard, or that it should be immediately buried in
  matter impervious to air and kept moist. The latter conditions are
  the more probable. The preservative qualities of the peaty vegetable
  matter imbedded with it must be considered; and it is possible that
  these hollow stumps, partly filled with fragments of _Sigillaria_
  bark, may have formed natural tan-pits, in which animal membranes
  would be preserved in a manner impossible in ordinary sediments. If
  this were the case, we may yet find an entire reptile, preserved as a
  flattened mummy, in one of these strange repositories."


=Genus PLATYSTEGOS Dawson, 1895.=

  Dawson, Proc. and Trans. Roy. Soc. Canada, 1895, XII, p. 77 (sec. IV).

Type: _Platystegos loricatum_ Dawson.

Dawson's description is as follows:

  "Head broad and short, orbits very large, cranial bones deeply
  sculptured; teeth strongly plicated and curved, with sharp edges at
  apices, especially the inner palatal teeth, which are very large. Many
  minute teeth on the vomerine bones; vertebræ ossified, biconcave; limb
  bones imperfectly ossified, short; lower surface protected with a
  thoracic plate and thick, densely imbricated bony scales in transverse
  rows; body above with thin, round scales, concentrically marked."


=Platystegos loricatum Dawson.=

  Dawson, Proc. and Trans. Roy. Soc. Canada, XII, p. 77, 1895.

Dawson describes the species:

  "Head about 8 cm. long; when flattened 9 cm. broad across parietal
  foramen; squamosal and temporal bones projecting backwards in points
  much behind the condyles; parietal foramen small, orbits large; length
  of longest tooth seen 7 mm.; cranial bones closely and deeply pitted;
  humerus with very thin bony walls, cartilaginous within, 3.5 cm. long."

Erect tree, coal formation, at the South Joggins; collected by P. W.
McNaughton. Type in Peter Redpath Museum at McGill University. Dawson
regarded the form as of uncertain relationship.



CHAPTER XXV.

THE STEREOSPONDYLOUS AMPHIBIA FROM THE COAL MEASURES OF NORTH AMERICA.


DEFINITION OF THE ORDER STEREOSPONDYLIA ZITTEL, 1887.

  Zittel, Handbuch der Paleontologie, Bd. III, Abth. 1, p. 397, 1887.

  Large terrestrial vertebrates; largest of the class. Skull equal to
  one-fourth or one-third of the entire body in at least one species,
  _Metoposaurus diagnosticus_ von Meyer (242). Lateral-line canals
  always present (458) on the skulls as deeply impressed grooves which,
  in life, were possibly roofed-over by a cartilaginous or other
  connective-tissue membrane. The sensory organs undoubtedly being
  supplied by the superficial ophthalmic branch of the trigeminal
  nerve, branches of which pierced the cranial elements near the
  grooves, no evidence of such openings in the bottoms of the grooves;
  the condition probably being analogous to _Hydrolagus colei_ and
  other chimæroids. Vertebræ stereospondylous, with well-developed
  neural arches from which projected the well-developed zygapophyses,
  sometimes slightly amphicœlous and pierced for the notochord, such
  forms being uncertainly placed in the group. Tail unknown, possibly
  short. Limbs and girdles well developed (243), phalangeal formula
  unknown; carpus osseous and tarsus unknown. Pectoral girdle composed
  of osseous scapulæ, clavicles, interclavicle, coracoid (?); clavicles
  and interclavicle ventrally sculptured. Pelvic girdle composed of
  osseous pubis, ischium, and ilium (242), the pubis a small plate, in
  life largely cartilaginous, the three uniting by cartilaginous union
  to form the acetabulum. Ventral armature unknown, possibly wanting.

Range: Pennsylvanian to Upper Triassic.

Distribution: North America, Europe, Asia, Africa, and Australia.


=Family MASTODONSAURIDÆ Huxley, 1863.=

  Huxley, Quart. Jour. Geol. Soc., XIX, p. 65, 1863.

  Lydekker, R., Cat. Fossil Reptilia Amphibia, pt. IV, p. 141, 1890.

  Skull triangular, and more or less elongated, with the cranial bones
  very strongly sculptured, the occipital condyles ossified (49), and
  large palatal vacuities; dentine of teeth with very complex plications
  (502); no bony rings (242) in sclerotic; and no ventral scutes.
  Bodies of vertebræ (49) fully ossified in the adult. There are large
  palato-vomerine tusks on the inner side of the maxillary teeth; and
  the palatines run parallel to the maxilla. The mandible has a large
  postarticular process; and there is a small inner series of mandibular
  teeth. In the type genus the pubes are separate from the ischia, and
  do not enter into the formation of the acetabulum; and the sacral ribs
  form kidney-shaped disks (393).

Represented in North America by a single tooth from the Carboniferous of
Kansas. Described by Williston as Mastodonsaurus sp. (Kans. Univ. Quart.,
VI, pp. 209-210, pl. XXI). Represented in the Triassic of Wyoming by
Anaschisma browni, Branson (49).


=Mastodonsaurus sp. indet.=

  Williston, Kans. Univ. Quart., VI, p. 209, 1897.

The specimen preserved comprises the entire crown of a single vomerine (?)
tooth, 38 mm. in length by 14 mm. in diameter at base (pl. 21, fig. 6).
The immediate tip had been partly worn away in life, but was acuminate.
It is composed of a dense blackish material, with the exterior smooth,
shining black. It has about 20 narrow flutings, nearly straight, running
from the base to the tip, separating shallow grooves. A transverse section
of the base shows a narrow pulp-cavity not more than 5 mm. in diameter
which extends in about the same proportional width to beyond the middle of
the tooth, and in all probability to near the apex. The cross-section of
the tooth throughout is nearly or quite circular.

A hemisection of the tooth was made near the middle, showing a structure
most remarkably like that of _Mastodonsaurus_; so nearly alike, in fact,
that there is no difference from the large figure given by Owen of a
section of _Mastodonsaurus_ (502).

The discovery of this tooth in the Kansas Coal Measures is of great
interest, proving, as it does, the presence of true labyrinthodonts from
a lower horizon than elsewhere recorded. The discovery of _Eobaphetes
kansensis_ Moodie in the Carboniferous of Washington County (473) would
seem to indicate another labyrinthodont. The tooth from Louisville was
possibly not the first evidence of labyrinthodonts in North America, since
the discovery by Marsh of _Eosaurus acadianus_ from the Coal Measures
of Nova Scotia, possibly a member of the Stereospondylia, antedates
this discovery 30 years. The specimen is preserved in the Museum at the
University of Kansas.


AMPHIBIAN FOOTPRINTS FROM THE COAL MEASURES.

Footprints may be said to be fairly common in the Coal Measures of North
America. Especial attention has been given to the classification of these
objects by G. F. Matthew (408-413), Dawson (208-210) and others. Hay (317,
pp. 538-553) has given a catalogue of all the species described from
the Coal Measures of North America, to which the reader is referred for
further information in regard to these interesting evidences of former
animal activities. The writer has not been interested in the taxonomy
of footprints, but has studied such as have come to his notice (465). A
description of the species _Dromopus agilis_ Marsh (fig. 43) is given
here, because there is a large slab in the University of Kansas Museum
which has not been figured. Since the chief interest in the present
contribution is morphology, footprints are thus scantily dealt with. Leidy
(374), Dawson (207), Moodie (465, pl. LXIV, fig. 1) and others have given
various brief descriptions of Coal Measures footprints, probably all of
which are evidences of Amphibia which are otherwise unknown.


=Dromopus agilis Marsh.=

  Marsh, Jour. Sci. (3), XLVIII, p. 82, pl. ii, fig. 3; pl. iii, fig. 3,
    1894.

  Hay, Bull. U. S. Geol. Surv., No. 179, p. 543, 1902.

Type: Specimen in the Yale University Museum.

Horizon and locality: Osage limestone (Coal Measures), near Osage City,
Kansas.

In 1894 Professor Marsh described a collection of footprints which
he had secured from Professor B. F. Mudge, of Manhattan, Kansas, who
had collected them in Osage County, Kansas, in a rock quarry, having
purchased a large quantity of rock from the quarrymen for that purpose. A
preliminary note by Mudge (490) was published in the Transactions of the
Kansas Academy of Science and later copied in the American Journal of
Science. Professor Marsh's description (406) of the remains is as follows:

  "The impressions are well preserved in a calcareous shale, which
  separates readily into thin slabs, each representing a surface of
  the beach at the time the footprints were made upon it. A few shells
  in the shale are sufficient to prove that the formation is marine
  (no shells are evident in the slab at the Museum of the University
  of Kansas, but the slab is quite arenaceous). Trails of annelids, or
  perhaps of other invertebrates, are seen on some of the surfaces.
  The footprints of vertebrate animals, however, are of paramount
  importance, and the large number and variety of these here recorded
  on a single surface, if they could be rightly interpreted, would form
  an interesting chapter of land vertebrate life in the Carboniferous,
  about which so little is at present known."

[Illustration: Fig. 43.--Footprints of _Dromopus agilis_ Marsh, from the
Coal Measures of Osage County, Kansas. Original slab in University of
Kansas Museum. Greatly reduced.]

Professor Marsh's description of _Dromopus agilis_ is as follows:

  "The third series of footprints is of special interest, and indicates
  an animal very distinct from the two already described. The diagram
  represents the impression of the phalanges sufficiently in detail to
  indicate (406) their number and general form. A striking feature in
  the fore and hind feet of this animal was the long, slender digits
  terminated by sharp claws. Another point of interest, as recorded in
  the footprints, is that the animal in walking swung the hind feet
  outward, and so near the ground that the ends of the longer toes
  sometimes made trails in the mud, marking accurately the sweep of the
  foot. This would seem to indicate a comparatively short hind leg,
  rather than the long, slender one which the footprints themselves
  naturally suggest.

  "The animal which made these interesting footprints was probably a
  Lacertilian rather than an Amphibian, but there is also a possibility
  that it was a primitive Dinosaur."

Further on Professor Marsh remarks (p. 84):

  "So far as at present known, land vertebrate life began in the
  Carboniferous age, no footprints of other remains of this kind having
  been detected below the Subcarboniferous. That such remains will
  eventually be found in the Devonian, there can be no reasonable doubt,
  and perhaps even in the Silurian, if the land surfaces then existing
  can be explored."

This last statement of Marsh's was, of course, partly demonstrated by
the discovery of footprints in the Devonian rocks of Pennsylvania, which
he described in 1896 as _Thinopus antiquus_. The footprints of _Dromopus
agilis_ Marsh which are preserved in obverse in the University of Kansas
Museum are of considerably greater length than those described by
Professor Marsh. The measurements of one of the larger impressions are
appended. There appear to be series of footprints of two different animals
preserved on the large slab (5 by 7 feet), but their nature is essentially
the same.

Measurements of Large Footprint.

                                            mm.
  Greatest length                           200
  Greatest width                             90
  Length of longest toe                     120
  Length of shortest toe                     65
  Width across heel                          50

The slab is No. 5 of the University of Kansas Museum of Natural History,
collected in 1873 by Professor B. F. Mudge at Osage, Kansas, and presented
by him to the museum in 1875.

The following list of Carboniferous amphibian (?) footprints is compiled
from Hay's Catalogue of Fossil Vertebrates of North America. It is given
here for the sake of completeness. Three types of amphibian footprints
are described in the body of this work and they constitute the kind of
material which an ichnologist has for the basis of his conclusions. The
material is not very satisfactory for the morphologist, though much can be
determined as to the foot structure.

  Genus and species.              | Author.  |Horizon.|   Locality.
  --------------------------------+----------+--------+------------------
  _Allopus littoralis_            | Marsh    |  CM    | Osage County, KS.
  _Anomæpus ? culbertsonii_       | King     |   "    | Pennsylvania.
  ---- _gallinuloides_            | King     |   "    |      "
  _Anthracopus ellangowensis_     | Leidy    |   "    |      "
  _Baropus lentus_                | Marsh    |   "    | Osage County, KS.
  _Batrachichnus plainvillensis_  | Woodworth|   "    | Massachusetts.
  _Cheirotherium ? heterodactylum_| .....    |   "    | Pennsylvania.
  ---- _reiteri_                  | Moore    |   "    |      "
  _Collettosaurus indianænsis_    | Cox      |   "    | Indiana.
  _Crucipes parvus_               | Butts    |   "    | Missouri.
  _Dromopus agilis_               | Marsh    |   "    | Osage County, KS.
  _Hylopus caudifer_              | Dawson   |   "    | Nova Scotia.
  ---- _hardingi_                 | Dawson   |   "    |      "
  ---- _logani_                   | Dawson   |   "    |      "
  ---- _minor_                    | Dawson   |   "    |      "
  ---- _trifidus_                 | Dawson   |   "    |      "
  ---- sp. indet                  | .....    |   "    |      "
  _Limnopus vagus_                | Marsh    |   "    | Osage County, KS.
  _Nanopus candatus_              | Marsh    |   "    |      "
  _Notalacerta missouriensis_     | Butts    |   "    | Missouri.
  _Notamphibia magna_             | Butts    |   "    |      "
  _Palæosauropus antiquior_       | Dawson   |  SC    | Nova Scotia.
  ---- _primævus_                 | Lea      |  CM    | Pennsylvania.
  ---- _sydenensis_               | Dawson   |   "    | Cape Breton Isl.
  ---- _unguifer_                 | Dawson   |  Cmg   | Nova Scotia.
  _Thenaropus leplodactylus_      | King     |  CM    | Pennsylvania.
  ---- _ovoidactylus_             | King     |   "    |      "
  ---- _pachydactylus_            | King     |   "    |      "
  ---- _sphærodactylus_           | King     |   "    |      "
  --------------------------------+----------+--------+------------------

  Horizon abbreviations
  ---------------------
  CM = Coal Measures.
  SC = Subcarboniferous.
  Cmg = Carboniferous (millstone grit).



BIBLIOGRAPHY OF THE FOSSIL AMPHIBIA, WITH ESPECIAL REFERENCE TO THE
AMPHIBIA FROM THE COAL MEASURES OF NORTH AMERICA.


The following literature list, containing more than six hundred titles
(1824-1916), is believed to be fairly complete. It certainly includes all
of the important contributions to the subject of the fossil Amphibia. A
few brief bibliographies of fossil Amphibia have appeared from time to
time, in special memoirs on various faunas, such as: Broili (58), Schwarz
(541), Fraas (242), von Ammon (7), and Case (98). None of these have
attempted a complete survey of the field. The references given below have
all, or nearly all, been compiled from the original sources and every
effort has been made to have them complete and accurate.

  1. Abel, O. 1912. Grundzüge der Paleobiologie der Wirbelthiere.
       211-220, figs. 144-150.

  2. Agassiz, L. 1862. Highly interesting discovery of new Sauroid
       remains. Amer. Jour. Sci. and Arts, Jan., XXXIII, 138.

  3. Alberti, Fr. v. 1834. Beitrag zu einer Monographic des bunten
       Sandsteins, Muschelkalks und Keuper.

  4. ----. 1864. Ueberblick ueber die Trias. 235-241.

  5. Albrecht, P. 1883. Note sur le Basioccipital des Batraciens
       Anoures. Bull, de Musee Roy. d'Hist. Nat. de Belgique, II,
       195-198, with figs, and a plate.

  6. American Naturalist. 1878. A new fauna, XII, 327-328 (Ed.).

  7. Ammon, Ludwig Von. 1889. Die permischen Amphibien der Rheinpfalz,
       Munich. 1-117, pls. 1-5, with extensive bibliography.

  8. Andrews, C. W. 1895. Note on a specimen of Keraterpeton galvani
       Huxley, from Staffordshire. Geol. Mag., Dec., IV, II, 81-84, fig.

  9. Arldt, Theodor. 1907. Die Entwicklung der Kontinente und ihre
       Lebewelt. 333, Karte 10.

  10. ----. 1909. Die Stegocephalen und ihre Stellung unter den
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  11. Atthey, T. 1876. On Anthracosaurus russelli. Ann. and Mag. Nat.
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  422. ----. 1844. Apatheon pedestris. Neues Jahrb. f. Mineral., Geol.
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  430. ----. 1851. Beschreibung der fossilen Decapoden, Fische,
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  433. ----. 1854. Mittheilung ueber Archegosaurus. Neues Jahrb. f.
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  434. ----. 1856. Ueber Osteophorus roemeri, Briefl. Mittheil. an
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  435. ----. 1857. Mittheilung an Professor Bronn. Neues Jahrb. f.
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  436. ----. 1857. Reptilien aus der Steinkohlenformation in
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  437. ----. 1857. Osteophorus roemeri, Beschreibung derselben in
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  438. ----. 1858. Reptilien aus der Kohlsteinformation in Deutschland.
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  439. ----. 1858. Labyrinthodonten aus dem bunten Sandstein von
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  440. ----. 1858. Mittheilung an Professor Bronn. Neues Jahrb. f.
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  441. ----. 1859. Mittheilung an Professor Bronn. Neues Jahrb. f.
       Mineral. Geol. u. Paleon.: Triton basalticus, 430; Andrias
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  589. ----. Paleontology of the Patty Coal Field. Mem. Geol Surv.
       United Kingdom, pt. III, 285-357.

  590. Watson, D. M. S. 1914. The Cheirotherium. Geol. Mag., VI, I, No.
       603, 395-398.

  591. ----. 1912. The larger Coal Measure Amphibia. Mem. and Proc.
       Manchester Lit. and Philos. Soc., LVII, pt. I, No. I, 1-4, 1 pt.

  592. ----. 1913. Batrachiderpeton lineatum, Hancock and Atthey, a
       Coal-Measure Stegocephalian. Proc. Lond. Zool. Soc., pt. IV,
       949-962, with 2 plates and figures in text.

  593. ----. 1913. The early evolution of the Amphibia. Rept. 83d
       Meeting British Assn. Adv. Sci., 532.

  594. ----. 1912. On some Reptilian lower jaws. Ann. and Mag. Nat.
       Hist., 8th series, vol. 10, July-Dec., 573-587. with figures.

  595. ----. 1913. Micropholis Stowi Huxley, a temnospondylous amphibian
       from South Africa. Geol. Mag., 5th Dec., 10, 340-346, with
       figures.

  596. Weiss, Ch. Ernst. 1871. Paleontologisch geognostische
       Untersuchungen aus dem Gebirge auf der Südseite der rheinischen
       Devons. Bonn. Sitzungsb. Niederrhein Gesell., 33-35.
       (Archegosaurus extremity.)

  597. ----. 1877. Ueber Protriton petrolei von Friedrichroda in
       Thüringen. Zeit. d. deutsch. geol. Gesell., XXIX, 202.

  598. Wheatley, Chas. M. 1871. The bone cave of eastern Pennsylvania.
       Amer. Jour. Sc. (3), I, 384-385.

  599. White, David. 1906. Geological position of the principal
       insect-bearing localities of the American Paleozoic, in
       "Handlirsch's Revision of American Paleozoic Insects." Proc. U.
       S. Nat. Mus., XXIX, No. 1441, 664-667.

  600. ----. 1907. Report of the field work in the coal districts of
       the state. Bull. No. 4, Illinois State Geol. Surv., 201. (Gives
       correlation of the Mazon Creek Beds.)

  601. Wiedersheim, Robert. 1876. Die ältesten Formen des Carpus und
       Tarsus der heutigen Amphibien. Morphol. Jahrb., Bd. 2, 421-423,
       Taf. XXIX, fig. 2.

  602. ----. 1878. Ueber Labyrinthodon ruetemeyeri--Anatomie der Gehirn.
       Abhandl. d. schweizer paleontol. Gesell., V, 1-56, mit 3 tafeln.

  603. ----. 1879. Die Anatomie der Gymnophionen, pp. 1-101, Tafeln
       i-ix. (Refers to extinct Amphibia in connection with phylogeny.)

  604. ----. 1886. Lehrbuch der vergleichenden Anatomie der
       Wirbelthiere. 2 Auflage.

  605. ---- and W. N. Parker. 1897. Elements of the comparative anatomy
       of vertebrates. Translated by W. N. Parker. Labyrinthodontia,
       242, fig. 1930.

  606. Wilder, H. H. 1909. History of the human body. Amphibia, 541-542.

  607. Williston, S. W. 1897. Some vertebrates from the Kansas Permian.
       Kans. Univ. Quart., ser. A, VI, No. I, 53, fig. Cricotus.

  608. ----. 1897. A new Labyrinthodont from the Kansas Carboniferous.
       Kans. Univ. Quart., VI, No. 4, ser. A, 309, fig. and pl. (Refers
       tooth and skull fragments to Mastodonsaurus.)

  609. ----. 1899. The Red-Beds of Kansas. Science (2), IX, 221.

  610. ----. 1899. Notes on the coraco-scapula of Eryops Cope. Kans.
       Univ. Quart., VIII, No. 4, 185-186, pls. xxvii-xxx. (See Moodie
       (476).)

  611. ----. 1900. Some fish teeth from the Kansas Cretaceous. Kans.
       Univ. Quart., ser. A, IX, No. 1, Jan., pl. vi, figs. 13, 133.

  612. ----.1904. The temporal arches of the Reptilia. Biol. Bull., VII,
       No. 4, 175-192.

  613. ----. 1908. The faunal relations of the early vertebrates. Jour.
       Geol., XVII, No. 5, 389-402. Also, Outlines of geologic history,
       Willis and Salisbury, 1910, 163-175.

  614. ----. 1908. Lysorophus, a Permian Urodele. Biol. Bull., XV, No.
       5, 229-240. Review in Rev. crit. de Paleozoologie 13th Annee, No.
       2, 82.

  615. ----. 1909. The skull and extremities of Diplocaulus. Trans.
       Kans. Acad. Science, XXII, 122-13 1, pls. 1-5.

  616. ----. 1909. New or little-known Permian vertebrates, Trematops,
       new genus. Jour. Geol., XVII, No. 7, Nov., 636-658, 7 figs.

  617. ----. 1909. Principal characters of the Chelydosauria, a suborder
       of temnospondylous Amphibians from the Texas Permian. A. A. A. S.
       Soc. Vert. Paleon.

  618. ----. 1910. Dissorophus. Jour. Geol., VIII, No. 6, 526-535, pls.
       i-iii.

  619. ----. 1910. Cacops, Desmospondylus, new genera of Permian
       Vertebrates. Bull. Geol. Soc. Amer., XXI, 249-284, pls. 6-17.

  620. ----. 1910. New Permian Reptiles: Rachitomous vertebræ. Jour.
       Geol., XXIII, No. 7, 585-600, with figs.

  621. ----. 1911. American Permian vertebrates. Amphibia, 9-14, pls.
       xxxii, xxxviii.

  622. ----. 1913. The primitive structure of the mandible in amphibians
       and reptiles. Jour. Geol., XXI, 625-627, 11 fig.

  623. ----. 1914. The osteology of some American Permian vertebrates.
       Jour. Geol., XXII, No. 4,416, figs.

  624. ----. 1914. Water reptiles of the past and present. Amphibia, 35,
       47, and figures.

  624_a_. ----. 1914. Broiliellus, a new genus of amphibians from the
       Permian of Texas. Jour. Geol., XXII, No. 1, 49-56, figs. 1-2.

  624_b_. ----. 1914. Restorations of some American Permocarboniferous
       amphibians and reptiles. Jour. Geol., XXII, No. 1, 57-70, figs.
       1-11.

  624_c_. ----. 1915. Trimerorhachis, a Permian temnospondyl amphibian.
       Jour. Geol., XXIII, No. 3, 246-255, figs. 1-6.

  624_d_. ----. 1916. Synopsis of the Amer. Permocarboniferous
       Tetrapoda. Contrib. from Walker Museum, vol. I, No. 9, pp.
       200-211, figs. 38-53.

  625. Wiman, Carl. 1908. Ein Paar Labyrinthodontenreste aus der Trias
       Spitzbergens. Bull. Geol. Inst. Univ. of Upsala, IX, 34-40,
       Tafeln II, Nos. 17, 18.

  626. ----. 1913. Ueber das Hinterhaupt der Labyrinthodonten. Bull.
       Geol. Inst. of Upsala, XII, 1-7, figs. 1-8.

  627. Wiman, Carl. 1914. Ueber die Stegocephalen aus der Trias
       Spitzbergens. Bull. Geol. Inst. of Upsala, XIII, 1-30, pls. i-ix,
       figs. 1-10, bibliography.

  628. Woodward, A. Smith. 1891. Catalogue of the fossil fishes in the
       British Museum, pt. II, 474. (Note on the synonymy of Pygopterus,
       Colosteus, and Archegosaurus.)

  629. ----. 1891. On a Microsaurian (Hylonomus wildii) from the
       Lancashire Coal Field. Geol. Mag., n. s., Dec. III, VIII,
       211-213, with figs.

  630. ----. 1897. On a new specimen of the Stegocephalian Ceraterpeton
       galvani Huxley. Geol. Mag., Dec. IV, IV, No. 397, 293, with plate.

  631. ----. 1904. On two new Labyrinthodont skulls of the genera
       Capitosaurus and Aphaneramma (from the Trias of Spitzbergen).
       Proc. Zool. Soc. London, 170-176, with 2 pls.

  632. ----. 1906. The relations of paleontology to biology. Ann. and
       Mag. Nat. Hist., XVIII, No. 106, 312-318.

  633. ----. 1905. Fishes and Labyrinthodonts. Paleontologica Indica, n.
       s., II, Memoir No. 2, 10, 2 pls.

  634. ----. 1909. On a new Labyrinthodont from Oil Shale, N. S. W. Rec.
       Geol. Surv. N. S. W., VIII, pt. IV, 317-319. Pl. 51.

  635. Woodward, H. B. 1887. The geology of England and Wales. The
       Northumberland Coal Field, 180.

  636. Woodworth, J. B. 1900. Vertebrate footprints on Carboniferous
       shales of Plainville, Mass. Bull. Geol. Soc. Amer., XI, 449-454,
       pl. 40, fig. 1.

  637. Wyman, Jeffries. 1843. Analogies which exist between the
       structure of the teeth of the Lepidostei (Gars and Gar-pikes) and
       those of the Labyrinthodonts (extinct Amphibia). Proc. Bost. Nat.
       Hist. Soc., I, 131-132; also Silliman's Journal, 843.

  638. ----. 1853. Notes on the Reptilian remains (Dendrerpeton). Quart.
       Jour. Geol. Soc. London, IX, 64-66.

  639. ----. 1856. On a batrachian reptile from the Coal Formation.
       Proc. Amer. Assn. Adv. Sci., 10th Meeting at Albany, 172-173.
       Reviews: Edinb. n. Philos. Jour. 1857, V, 360-361; Neues Jahrb.
       f. Mineral., Geol. u. Paleon., I. 857, 340.

  640. ----. 1858. On some remains of batrachian reptiles discovered in
       the Coal Formation of Ohio. Amer. Jour. Science, XXV (2), Mar.,
       158-164, fig. Review: Zeit. f. gesammt Naturwissensch., XIII, 71;
       Neues Jahrb. f. Mineral., Geol. u. Paleon., 1858, 340.

  641. Yakowlew, N. 1902. Neue Funde von Trias--Saurier auf Spitzbergen.
       Verhandl. Russ. k. Min. Gesell., XL, 180; Nachtrag, XLI, 165.

  642. Zittel, Karl Von. 1887-1890. Handbuch der Paleontologie, I Abth.,
       Bd. in, 337-437, Amphibia. München u. Leipsic, R. Oldenbourg,
       also Eastman's translation of above, 2, 114-139, figs.

  643. ----. 1888. Ueber Labyrinthodon ruetimeyeri (Wiedersheim). Neues
       Jahrb. f. Mineral., Geol. u. Paleon., Bd. II, 17. (Regards the
       form as a reptile.)

  644. ----. 1899. Amphibien. Geschichte der Geologie und Paleontologie.
       Muenchen u. Leipzig, 1899, 827.

  645. Zwick, W. 1897. Beiträge zur Kenntniss des Baues und der
       Entwickelung der Amphibiengliedmassen, besonders des Carpus und
       Tarsus. Zeitschr. wissen. Zool., Bd. 63, 62-144, Taf. 4-5.



AN INDEX TO THE BIBLIOGRAPHY OF FOSSIL AMPHIBIA.


The following will be of assistance to those wishing aid in finding
the literature on special phases, whether anatomical or geological, of
the fossil Amphibia. The author's name and the number of his paper in
the preceding bibliography are given in groups of classified subjects,
beginning with distribution and ending with anatomy. The various
anatomical notes of interest are especially widely scattered in papers
which often deal with a variety of other subjects.

  I. Geological and Geographical Distribution.

  Devonian:
    North America: Marsh, 407.
    Europe: Lohest, 381; Weiss, 596; Thevenin, 566.

  Mississippian:
    North America: Branson, 50; Barrell, 21; Lea, 371-372.
    Scotland: Huxley, 331-334; Atthey, n; Hancock and Atthey, 305.

  Coal Measures (Pennsylvanian):
    North America: Agassiz, 2; Butts, 82, 83; Case, 86,
      94; Cope, 105, 107, 115, 116, 118, 122, 123, 126,
      127, 131, 145, 152, 167, 176; Dawson, 200-225;
      Eastman, 230; Hay, 316; Jaekel, 347; King,
      356, 357; Marsh, 404, 406; G. F. Matthew,
      408-413; Moodie, 458-465. 469-475, 478, 479,
      482-486; Mudge, 490; Newberry, 495-498; Raymond,
      531; Schwarz, 540, 541; Williston, 608;
      Wyman, 639, 640.

    Europe: Andrews, 8; Atthey, n; Bailey, 12-13;
      Barkas, 15-20; Bolton, 42-43; Credner, 179-194
      (see also under Permian); Davis, 199; Dunlop,
      229; Embleton and Atthey, 235; Etheridge,
      241; Fritsch, 251; Gaudry, 263-268, 278, 281,
      282; Gergens, 291; Goldfuss, 297; Hancock and
      Atthey, 304-310; Lydekker, 394; von Meyer,
      422, 426, 436; Oldham, 500; Owen, 507-509,
      514, 515; Schwarz, 540; Thevenin, 565-568;
      Weiss, 597; Woodward, 629, 630; Woodworth,
      636.

    Australia: Stephens, 557; Woodward, 634.

  Permian:

    North America: Broili, 55, 56, 58, 63, 65; Case, 86-93,
      95-100; Cope, 129, 132-133, 137, 138, 140-144,
      156, 169, 170-175; Emmons, 237; Gregory, 299;
      W. D. Matthew, 414, 415; Moodie, 457, 458,
      476, 477; Sternberg, 558; Strickler, 564; Williston,
      607, 609, 610, 614, 615, 616, 617-624.

    Europe: Ammon, 7; Branco, 48; Broili, 59, 60, 61,
      62, 66; Credner, 179-195; Deichmueller, 224,
      225; Eichwald, 233; Emery, 236; Fritsch, 251;
      Gaudry, 258-261, 269-282; Geinitz, 287; Geinitz
      und Deichmueller, 289, 290; Goldfuss, 295, 296;
      von Huene, 324-327; Huxley, 328; Jaekel, 344,
      345; Le Roy, 375; Lloyd, 379; Lortet, 382; von
      Meyer, 428, 436, 442; Roemer, 534; Trautschold,
      573; Twelvetrees, 576.

    Africa: Broom, 68-71-73, 74.

    Asia: Lydekker, 384, 386; Huxley, 333; Woodward, 633.

  Triassic:

    North America: Branson, 49; Cope, 106, in, 121,
      157; Emmons, 237; Leidy, 373; Lucas, 383.

    Europe: Alberti, 4; Burmeister, 80, 81; Fraas, 242-245,
      247_a_; von Huene, 323; Huxley, 329; Jaeger,
      338-341; Metcalfe, 417; von Meyer, 421, 425,
      439; Miall, 453; Owen, 505; Quenstedt, 527;
      Seeley, 544; Storrie, 560; Ward, 588; Wiedersheim,
      602; Woodward, 631.

    Spitzbergen: Wiman, 625-627; Woodward, 631;
      Yakowlew, 641; Seeley, 547.

    Africa: Broom, 69; Huxley, 330; Owen, 517, 519-520.

    Asia: Lydekker, 384-391; Owen, 510, 511.

    Australia: Huxley, 330; Stephens, 554, 555.

  Jurassic:

    Europe: Dollo, 226.

  Comanchean:

    North America: Marsh, 405; Moodie, 480, 481.

    Europe: Vidal, 579, 580.

  Cretaceous:

    North America: Cope, 128; Hatcher, 314; Lambe,
      365, 366; Williston, 611.

  Tertiary:

    Europe: Beyrich, 36; Bieber, 37; Cuvier, 197; Fraas,
      246, 247; Günther, 301; Laube, 367-370; von
      Meyer, 424, 430, 444, 446, 447; Portis, 525;
      Scheuchzer, 535; Tschudi, 574-575; Walterstorff,
      585-586.

  Pleistocene:

    North America: Brown, 76; Wheatley, 598.

    South America: Lydekker, 393.

    Asia: Clark, 103; Lydekker, 393; Owen, 506.

    Europe: Lydekker, 393.


  II. Phylogeny of Amphibia.

  Arldt, 10; Baur, 22-25, 31; Boulenger, 44; Branson, 49;
    Budgett, 79; Cope, 153, 166, 173; Davison, 198; Dollo,
    228; Gadow, 256; Gaudry, 280, 282; Gregory, 299,
    300, 300_a_; Haeckel, 312; Huxley, 337; Kingsley, 358;
    Moodie, 489_b_; Owen, 512; Pollard, 524; Quenstedt,
    527; Thevenin, 567-568; Versluys, 578; Vogt, 581;
    Wiedersheim, 601.


  III. Ontogeny of Amphibia.

  Ammon, 7; Credner, 187; Fritsch, 251; Hay, 315; von
    Meyer, 422; Thevenin, 566.


  IV. Structure and Morphology of Amphibia.

  Lateral-line System of Sensory Organs: Andrews, 8; Baur,
    31; Branson, 49; Fraas, 242, 2470; Huxley, 333; Malbranc,
    401; Miall, 450; von Meyer, 436; Moodie, 458,
    465, 478, 488; Thevenin, 568.

  Pineal Eye: Cope, 160; Credner, 187; Jaekel, 346.

  Morphology of the Skull: Albrecht, 5; Baur, 24, 27, 29,
    31; Boulenger, 44; Branson, 49; Broili, 55, 56, 66;
    Case, 85, 93, 98; Cope, 136, 177; Credner, 187-191;
    Fraas, 242, 247_a_; Fritsch, 251; Fuchs, 255; Gaupp,
    283; Goodrich, 298; Jaekel, 347; Maggi, 397, 398;
    von Meyer, 428, 436, 439; Moodie, 458, 478; Owen,
    511; Seeley, 546; Thevenin, 568; Thyng, 570; Williston,
    612, 614, 615, 616, 619; Wiman, 626; Woodward,
    631.

  Brain: Wiedersheim, 602; Moodie, 487.

  Ear: Cope, 159; Broom, 75.

  Eye: Cope, 105, 107; Moodie, 478.

  Teeth: Broili, 58; Credner, 194; Fraas, 242; Fritsch, 251;
    Jaekel, 342; Owen, 502, 503, 504, 505; Seeley, 548;
    Strickler, 564; Tomes, 571-572; Williston, 608; Wyman,
    637.

  Gills: Budgett, 79; Credner, 187; Cope, 123; Fritsch,
    251; Gaudry, 268; Thevenin, 566-568; von Meyer,
    436.

  Vertebræ and Ribs: Baur, 25, 26; Broili, 61; Case, 98;
    Cope, 133, 136, 142, 148, 153; Credner, 179-193;
    Fraas, 242; Fritsch, 251; Gadow, 256; Gegenbaur,
    284; Jaekel, 344, 348; Lillie, 378; Marsh, 404; von
    Meyer, 436; Mivart, 456; Moodie, 468; Schwarz,
    540, 541; Thevenin, 565-568; Williston, 620.

  Pectoral and Pelvic Arches: Broili, 62; Broom, 72; Cope,
    161; Credner, 180-185; Fritsch, 251; Gregory, 299,
    300_a_; Gegenbaur, 285; Jaekel, 347; Moodie, 478;
    Williston, 610, 616.

  Limbs, Carpus, and Tarsus: Baur, 22, 23, 28; Cope, 161;
    Credner, 180-185; Emery, 236; Fritsch, 251; Gregory,
    299-3003; Jaekel, 347; Wiedersheim, 601; Zwick, 645.

  Clasping Organs: Barkas, 16; Blanchard, 39; Braun, 52;
    Hilton, 319; Moodie, 461; Fritsch, 251; Stock, 561;
    Newberry, 498.

  Muscles: Moodie, 464.

  Alimentary Canal: Moodie, 471, 474, 478.

  Integument, Scales, and Structure of Bone: Jaekel, 343;
    Moodie, 464, 465, 478; Broili, 62; Dawson, 208.

  Footprints: Barrell, 21; Branson, 50; Brodie, 54; Bulls,
    82-83; Dawson, 207, 208; Fritsch, 251; Geinitz, 288;
    Hickling, 318; King, 356-357; Lea, 371, 372; Leidy,
    374; Marsh, 406; G. F. Matthew, 408-413; Owen,
    504; Moodie, 465; Pabst, 521; Smith, 549; Woodworth,
    636.



INDEX.


                                                PAGE.

  Aistopoda                                    5, 77
  Alimentary Canal                            25, 58
  Amblyodon                                      178
    A. problematicum                             179
  American Museum                               1, 8
  Ames Limestone                                  12
  Amphibamus                                     127
    A. grandiceps                      2, 7, 15, 128
    A. thoracatus                                132
  Amphibamidæ                                    127
  Amphibia                                         3
    Classification                                46
    Definition                                    49
    Discovery in Carboniferous                     6
    Geographic and Geologic Distribution           9
    History of Classification                     39
  Anaschisma, Lateral Line System of              35
  Anisodexis                                     164
  Anthracosauridæ                                187
  Apoda                                           33
  Archegosaurus                             1, 7, 35
  Arm                                             29
  Atlas                                           27
  Axis                                            27

  Baphetes                                       188
    B. minor                                     189
    B. planiceps                              6, 188
  Baur, George                                    39
  Brachydectes newberryi                         177
  Branchiosauria                               4, 50
  Branchiosauridæ                                 51
  Branchiosaurus                                  53
  Branson, E. B.                             38, 192
  Brown, N. H.                                    12
  Budgett, J. S.                                  78

  Cannelton Slates                            10, 15
  Carr, J. C.                             13, 14, 22
  Case, E. C.                                 9, 182
  Caudata                                         67
  Cephalerpeton ventriarmatum                    133
  Cercariomorphus parvisquamis                   139
  Clepsydrops Shales                               9
  Cocytinidæ                                      67
  Cocytinus gyrinoides                            68
  Cope, E. D.          1, 7, 9, 34, 42, 43, 131, 207
  Credner, Hermann                         1, 24, 52
  Cricotidæ                                      180
  Ctenerpeton alveolatum                         168

  Dawson, Sir J. W.   7, 8, 19, 20, 32, 66, 194, 197
  Dean, Bashford                          1, 32, 187
  Dendrerpeton                               19, 194
    D. acadianum                                 194
    D. oweni                                     196
  Dermal Appendages                              197
  Devonian                                    10, 37
  Diceratosaurus                              8, 116
    D. lævis                                     121
    D. punctolineatus                            117
    D. robustus                                  123
  Diplocaulia                                     34
  Dromopus                                   37, 201
    D. aduncus                                    37
    D. agilis                                    201

  Eobaphetes                                     191
    E. kansensis                                 192
  Eosauravus                              1, 87, 176
  Eosaurus acadianus                          7, 189
  Eoserpeton tenuicorne                          124
  Erierpeton branchialis                          69
  Erpetobrachium mazonensis                      152
  Erpetosaurus                                    97
    E. acutirostris                              108
    E. minutus                                   105
    E. obtusus                                    99
    E. radiatus                                   98
    E. sculptilis                                106
    E. tabulatus                                 101
    E. tuberculatus                              110
  Eryopidæ                                       182
  Eryops                                 23, 34, 182
  Euamphibia                                  46, 49
  Eumicrerpeton parvum                            57
  Eurythorax sublævis                            172
  Eye                                        25, 131

  Footprints                                 15, 201
  Fritsch, Anaton                      5, 54, 77, 78
  Fritschia curtidentata                          85

  Gergens, Dr.                                     6
  Gurley, W. F. E.                             9, 12

  Hay, O. P.                                  8, 129
  Hussakof, Louis                         1, 16, 172
  Huxley, Thomas H.                           3, 137
  Hylerpeton                                      83
    H. dawsonii                                   83
    H. intermedium                                84
    H. longidentatum                              84
  Hylonomidæ                                      79
  Hylonomus                                       79
    H. latidens                                   81
    H. lyelli                                     80
    H. multidens                                  81
    H. wymani                                     81
  Hylopus logani                                   6
  Hyoid                                           25
  Hyphasma lævis                                   7

  Ichthycanthidæ                                 173
  Ichthycanthus                                  173
    I. ohiensis                                  173
    I. platypus                                  174
  Ichthyerpeton squamosum                        137

  Jaekel, Otto                                8, 118
  Joggins, The South (Nova Scotia)                19

  Kammplatten                                      5
  Kittanning Coal                             15, 16

  Lacoe, R. D. (Collection of)                     1
  Lateral Line System                             32
  Leg                                          3, 95
  Lepospondylia                                   76
  Leptophractus                                  169
    L. dentatus                                  171
    L. lineolatus                                171
    L. obsoletus                                 169
  Linton, Ohio, Coal Measures                     16
    Amphibia of                                   18
  Logan, William                                   6
  Louisville, Kansas                              10
  Lydekker, Richard                           44, 77
  Lyell, Charles                              19, 20

  Macrerpetidæ                                   183
  Macrerpeton                                    184
    M. deani                                     186
    M. huxleyi                                   184
  Mandible                                   25, 103
  Marsh, O. C.                      10, 37, 189, 202
  Mastodonsauridæ                                 20
  Mastodonsaurus sp. indet                       200
  Matthew, G. F.                               8, 22
  Mauch Chunk                                     37
  Mazon Creek Shales                           7, 12
    Amphibia of                                   13
  Mazonerpeton                                    61
    M. costatum                                   63
    M. longicaudatum                              61
  Meyer, Hermann von                               6
  Micrerpeton                                     51
    M. caudatum                                   52
  Microsauria                               4, 34 76
    Relation to Reptilia                          77
  Mississippian Amphibia                          37
  Molgophidæ                                     149
  Molgophis                                      149
    M. brevicostatus                             150
    M. macrurus                                  149
    M. wheatleyi                                 151
  Morphology of Coal Measures Amphibia            23
  Muscle                                          32
  Myocommata                                      30

  Necturus                                    33, 56
  Newberry, J. S. (Collections of)      1, 8, 17, 18
  Nyraniidæ                                      137

  Occiput                                         25
  Odonterpeton triangularis                      111
  Œstocephalus                                   145
    O. rectidens                                 147
    O. remex                                     145
  Operculum                                      172
  Osage City, Kansas                              10

  Palate                                     24, 104
  Parabatrachus                                    7
  Pectoral Girdle                            29, 107
  Pelion                                       7, 72
    P. lyelli                                     73
  Peliontidæ                                      72
  Pelvic Girdle                                   29
  Phlegethontia                                  155
    P. linearis                                  156
    P. serpens                                   156
  Phoenix Tunnel, Pennsylvania                    10
  Pholidogaster                                    3
  Pitcairn, Pennsylvania                          12
  Platystegos loricatum                          199
  Pleuroptyx clavatus                    12, 19, 153
  Proteida                                        67
  Proterpeton gurleyi                        12, 178
  Ptyoniidæ                                      141
  Ptyonius                                       141
    P. marshii                                   143
    P. nummifer                                  144
    P. pectinatus                                141
    P. serrula                                   144
    P. vinchellianus                             143

  Raniceps                                         7
  Ribs                                            27

  Salientia                                       72
  Saurerpeton latithorax                         165
  Sauropleura                                    157
    S. digitata                                  159
    S. (Anisodexis) enchodus                     164
    S. foveata                                   163
    S. longidentata                              162
    S. newberryi                                 160
    S. pauciradiata                              160
    S. scutellata                                158
  Sauropleuridæ                              30, 157
  Scales                                     31, 197
  Schwarz, Hugo                                8, 28
  Sclerotic plates                                24
  Scutes                                         162
  Skin                                      164, 197
  Skull                                           23
  Smilerpeton aciedentatum                        82
  South Joggins, Nova Scotia                   7, 19
  Sparodus sp.                                    66
  Spondylerpeton spinatum                        181
  Stegopidæ                                      113
  Stegops                                        113
    S. divaricata                                114
  Stereospondylia                         5, 34, 200
  Sternum                                         30

  Tarsus                                         176
  Teeth                                           25
  Temnospondylia                          5, 34, 180
  Thinopus antiquus                           10, 37
  Thyrsidium fasciculare                          147
  Traquair, R. H.                                  5
  Triton walthi                                   50
  Tuditanidæ                                      86
  Tuditanus                                       86
    T. brevirostris                               89
    T. longipes                                   90
    T. minimus                                    92
    T. punctulatus                                87
    T. walcotti                                   94
  Twin Mounds, Kansas                             22

  Udden, J. A.                                    11
  Urocordylidæ                                  116

  Ventral Scutellæ                                30
  Vertebræ                                   27, 181
  Vertebral Column                                27

  Wiedersheim, Robert                             30
  Williston, S. W.                        2, 10, 200
  Wyman, Jeffries                                  7

  Zamenis flagellum                                5


       *       *       *       *       *


Transcriber Note

Images were moved to prevent splitting paragraphs. Hyphenation was
standardized to the most prevalent form. The table on page 201 was
modified (Horizon names and Kansas were abbreviated) to reduce the width.





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