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Title: The Cambridge Natural History, Vol X., Mammalia
Author: Beddard, Frank Evers
Language: English
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Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

*** Start of this Doctrine Publishing Corporation Digital Book "The Cambridge Natural History, Vol X., Mammalia" ***

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Transcriber's note: A few typographical errors have been corrected: they
are listed at the end of the text.

       *       *       *       *       *


THE

CAMBRIDGE NATURAL HISTORY

EDITED BY

S. F. HARMER AND A. E. SHIPLEY

       *       *       *       *       *

VOLUME X

MAMMALIA

by F. BEDDARD

Reprint Edition

_1958_

CODICOTE, ENGLAND WHELDON & WESLEY, LTD.

WEINHEIM, GERMANY H. R. ENGELMANN (J. CRAMER)

NEW YORK HAFNER PUBLISHING CO.

© 1902, by Macmillan & Co., Limited

Authorized reprint by
Wheldon & Wesley, Ltd. and H. R. Engelmann (J. Cramer)

Printed in Germany

       *       *       *       *       *


{iii}

PREFACE

Inasmuch as Sir W. H. Flower and Mr. Lydekker could not profess to treat
the Mammalia exhaustively within the limits of nearly 800 pages, in their
_Introduction to the Study of Mammals_, it is obvious that the present
volume, which appears ten years later and is of rather less size, can
contain but a selection of the enormous mass of facts at the disposal of
the student of this group. Thus the chief question for myself was what to
select and what to leave aside. It will be observed that I have reduced the
pages of this book to conformity with those of other volumes of the series
by treating some groups more briefly than others. It has appeared to me to
be desirable to treat fully such groups as the Edentata and the
Marsupialia, and permissible to be more brief in dealing with such huge
Orders as those of the Rodentia and Chiroptera. Lengthy disquisitions upon
such familiar and comparatively uninteresting animals as the Lion and
Leopard have been curtailed, and the space thus saved has been devoted to
shorter and more numerous accounts of other creatures. As there are nearly
six hundred genera of living Mammals known to science, omission as well as
compression became an absolute necessity. I have given, I hope, adequate
treatment from the standpoint of a necessarily limited treatise to the
majority of the more important genera of Mammals both living and extinct;
but the length of this part of the book had to be increased by the
discoveries, which give me at once an advantage and a disadvantage as
compared with the two authors whose names I have quoted, of a considerable
number of important new types in the last ten years. {iv} Such forms as
_Notoryctes_, _Romerolagus_, _Caenolestes_, "_Neomylodon_," and _Ocapia_
could not possibly have been omitted.

In preparing my accounts of both living and extinct forms I have nearly
invariably consulted the original authorities, and have often supplemented
or verified these accounts by my own dissections at the Zoological
Society's Gardens. My rule has not, however, been invariable in this
matter, inasmuch as there exist two recent and trustworthy text-books of
Mammalian Palaeontology--Professor Zittel's _Handbuch der Palaeontologie_,
and Dr. A. Smith Woodward's manual, _Outlines of Vertebrate Palaeontology_,
in the Cambridge Biological Series. Where the name of a genus only or its
range, or merely one or two facts about it, are mentioned, I have not
thought it necessary to go further than these two works. But a good deal
has been done even since the appearance of these two volumes which it will
be found that I have not ignored.

I have to thank my editors for the trouble which they have taken in the
revision of the proofs and for many suggestions. To Professor Osborn, of
Columbia University, New York, I am indebted for some kind suggestions. My
daughter Iris has assisted me in various ways. Finally, I desire to express
my indebtedness to Mr. Dixon and to Mr. M. P. Parker for the care which
they have taken in the preparation of the figures which were drawn by them
especially for this work.

  FRANK E. BEDDARD.
  LONDON, _February 28, 1902_.

       *       *       *       *       *


{v}

CONTENTS

                                                                       Page

  PREFACE                                                               iii

  SCHEME OF THE CLASSIFICATION ADOPTED IN THIS BOOK                      ix

  CHAPTER I

  INTRODUCTORY                                                            1

  CHAPTER II

  STRUCTURE AND PRESENT DISTRIBUTION OF THE MAMMALIA                      5

  CHAPTER III

  THE POSSIBLE FORERUNNERS OF THE MAMMALIA                               90

  CHAPTER IV

  THE DAWN OF MAMMALIAN LIFE                                             96

  CHAPTER V

  THE EXISTING ORDERS OF MAMMALS: PROTOTHERIA--MONOTREMATA              105

  CHAPTER VI

  INTRODUCTION TO THE SUB-CLASS EUTHERIA                                116

  CHAPTER VII

  EUTHERIA--MARSUPIALIA                                                 122
  {vi}

  CHAPTER VIII

  EDENTATA--GANODONTA                                                   161

  CHAPTER IX

  UNGULATA--CONDYLARTHRA--AMBLYPODA--ANCYLOPODA--TYPOTHERIA--
      TOXODONTIA--PROBOSCIDEA--HYRACOIDEA                               195

  CHAPTER X

  UNGULATA (_continued_)--PERISSODACTYLA (ODD-TOED UNGULATES)--
      LITOPTERNA                                                        235

  CHAPTER XI

  UNGULATA (_continued_)--ARTIODACTYLA (EVEN-TOED UNGULATES)--SIRENIA   269

  CHAPTER XII

  CETACEA--WHALES AND DOLPHINS                                          339

  CHAPTER XIII

  CARNIVORA--FISSIPEDIA                                                 386

  CHAPTER XIV

  CARNIVORA (_continued_)--PINNIPEDIA (SEALS AND WALRUSES)--CREODONTA   446

  CHAPTER XV

  RODENTIA--TILLODONTIA                                                 458

  CHAPTER XVI

  INSECTIVORA--CHIROPTERA                                               508

  CHAPTER XVII

  PRIMATES                                                              533

  INDEX                                                                 591

       *       *       *       *       *


{vii}

Scheme of the Classification Adopted In This Book

  Sub-Class Prototheria (p. 105).

  Order.         Sub-order.         Family.                 Sub-family.

  MONOTREMATA  {                { Echidnidae (p. 110).
   (p. 106)    {                { Ornithorhynchidae
                                {  (p. 112).
  ?ALLOTHERIA
   (p. 96).

                     Sub-class Eutheria (p. 116)

               {                 { Macropodinae   { Macropodinae (p. 132).
               {                 {  (p. 129)      { Potoroinae (p. 137).
               {                 {                { Hypsiprymnodontinae
               {                 {                {  (p. 138).
               {                 {
               { Diprotodontia   { Phalangeridae  { Phalangerinae (p. 140).
               {  (p. 128)       {  (p. 138)      { Phascolarctinae
               {                 {                {  (p. 144).
               {                 {                { Phascolomyinae
               {                 {                {  (p. 144).
  MARSUPIALIA  {                 {                { Tarsipedinae (p. 145).
   (p. 122)    {                 { Epanorthidae (p. 145).
               {
               {                 { Dasyuridae (p. 149).
               { Polyprotodontia { Didelphyidae (p. 155).
               {   (p. 149)      { Peramelidae (p. 156).
               {                 { Notoryctidae (p. 158).

               {                 { Myrmecophagidae (p. 166).
               {                 { Bradypodidae (p. 170).
               { Xenarthra       { Dasypodidae (p. 173).
  EDENTATA     {  (p. 166)       { Mylodontidae (p. 179).
  (p. 161)     {                 { Megalonychidae (p. 183).
               {                 { Megatheriidae (p. 183).
               {                 { Glyptodontidae (p. 184).
               {
               { Nomarthra       { Orycteropodidae (p. 187).
               {  (p. 186)       { Manidae (p. 188).

  GANODONTA    {                 { Stylinodontidae (p. 191).
   (p. 190)    {                 { Conoryctidae (p. 193).
  {viii}

               { Condylarthra (p. 202).
               { Amblypoda (p. 205).
               { Ancylopoda (p. 211).
               { Typotheria (p. 212).
               { Toxodontia (p. 214).
               { Proboscidea     { Elephantidae (p. 217).
               {  (p. 216)       { Dinotheriidae (p. 231).
               { Hyracoidea (p. 232).
               {                 { Equidae (p. 237).
               {                 { Lophiodontidae (p. 247).
               { Perissodactyla  { Palaeotheriidae (p. 247).
               {  (p. 235)       { Tapiridae (p. 260).
               {                 { Rhinocerotidae (p. 253).
               {                 { Titanotheriidae (p. 264).
  UNGULATA     {
   (p. 195)    { Litopterna      { Macraucheniidae (p. 267).
               {  (p. 267)
               {
               {                 { Hippopotamidae (p. 273).
               {                 { Suidae (p. 275).
               {                 { Dicotylidae (p. 278).
               {                 { Tragulidae (p. 282).
               {                 { Proceratidae (p. 284).
               {                 { Camelidae (p. 285).
               {                 { Cervidae (p. 291)  { Cervinae (p. 293).
               {  Artiodactyla   {                    { Moschinae (p. 299).
               {   (p. 269)      { Giraffidae (p. 301).
               {                 { Antilocapridae (p. 306).
               {                 { Bovidae (p. 307).
               {                 { Anthracotheriidae (p. 328).
               {                 { Caenotheriidae (p. 329).
               {                 { Xiphodontidae (p. 329).
               {                 { Oreodontidae (p. 330).
               {                 { Anoplotheriidae (p. 332).

  SIRENIA (p. 333).

               { Mystacoceti     { Balaenopteridae
               {  (p. 353)       {  (p. 355).
               {                 { Balaenidae (p. 358).
  CETACEA      {
   (p. 339)    { Odontoceti      { Physeteridae    { Physeterinae (p. 363).
               {  (p. 362)       {  (p. 362)       { Ziphiinae (p. 367).
               {                 { Delphinidae (p. 372).
               {                 { Platanistidae (p. 380).
               {                 { Squalodontidae (p. 384).
               {
               { Archaeoceti     { Zeuglodontidae (p. 384).
               {  (p. 384)

               {                 { Felidae (p. 390).
               {                 { Machaerodontidae
               {                 {  (p. 401).
               {                 {
               {                 {              { Euplerinae (p. 403).
               {                 {              { Galidictiinae (p. 404).
               {                 { Viverridae   { Cryptoproctinae (p. 404).
               {                 {  (p. 403)    { Viverrinae (p. 405).
  CARNIVORA    { Fissipedia      {              { Herpestinae (p. 409).
  {ix}
   (p. 386)    {  (p. 387)       { Hyaenidae (p. 411).
               {                 { Canidae (p. 413).
               {                 { Procyonidae (p. 426).
               {                 {                   { Melinae (p. 432).
               {                 { Mustelidae        { Mustelinae (p. 433).
               {                 {  (p. 431)         { Lutrinae (p. 439).
               {                 { Ursidae (p. 442).
               {
               { Pinnipedia      { Otariidae (p. 450).
               {  (p. 446)       { Trichechidae (p. 451).
               {                 { Phocidae (p. 452).

  CREODONTA
  (p. 455).

               {                 { Anomaluridae (p. 462).
               {                 { Soiuridae (p. 463).
               {                 { Castoridae (p. 467).
               {                 { Haplodontidae (p. 469).
               {                 { Gliridae (p. 470).
               {                 {                { Murinae (p. 471).
               {                 {                { Phlaeomyinae (p. 473).
               {                 {                { Hydromyinae (p. 474).
               {                 {                { Rhynchomyinae (p. 474).
               {                 {                { Gerbillinae (p. 475).
               {                 { Muridae        { Otomyinae (p. 475).
               {                 {  (p. 471)      { Dendromyinae (p. 476).
               {                 {                { Lophiomyinae (p. 476).
               {                 {                { Microtinae (p. 477).
               {                 {                { Sigmodontinae (p. 479).
               { Simplicidentata {                { Neotominae (p. 480).
  RODENTIA     {  (p. 462)       { Bathyergidae (p. 480).
   (p. 458)    {                 { Spalacidae (p. 482).
               {                 { Geomyidae (p. 483).
               {                 { Heteromyidae (p. 484).
               {                 { Dipodidae (p. 484).
               {                 { Pedetidae (p. 486).
               {                 {                 { Octodontinae (p. 487).
               {                 { Octodontidae    { Loncherinae (p. 488).
               {                 {  (p. 487)       { Capromyinae (p. 489).
               {                 { Ctenodactylidae (p. 490).
               {                 { Caviidae (p. 491).
               {                 { Dasyproctidae (p. 493).
               {                 { Dinomyidae (p. 495).
               {                 { Chinchillidae (p. 496).
               {                 { Cercolabidae (p. 497).
               {                 { Hystricidae (p. 499).
               {
               { Duplicidentata  { Leporidae (p. 502).
               {  (p. 502)       { Lagomyidae (p. 505).

  TILLODONTIA
   (p. 506).

               {                 { Erinaceidae (p. 509).
               {                 { Tupaiidae (p. 511).
               {                 { Centetidae (p. 511).
               { Insectivora     { Potamogalidae (p. 513).
               {   Vera          { Solenodontidae (p. 513).
               {  (p. 509)       { Chrysochloridae (p. 514).
  INSECTIVORA  {                 { Macroscelidae (p. 515).
    (p. 508)   {                 { Talpidae (p. 516).
               {                 { Soricidae (p. 518).
               {
               { Dermoptera      { Galeopithecidae (p. 520).
               {  (p. 520)
  {x}

               { Megachiroptera  { Pteropodidae (p. 524).
               {  (p. 524)
               {
               {                 { Rhinolophidae (p. 527).
  CHIROPTERA   {                 { Nycteridae (p. 527).
   (p. 521)    { Microchiroptera { Vespertilionidae (p. 528).
               {  (p. 526)       { Emballonuridae (p. 530).
                                 { Phyllostomatidae
                                 {  (p. 531).

               {                 {                  { Indrisinae (p. 538).
               {                 { Lemuridae        { Lemurinae (p. 540).
               {                 {  (p. 538)        { Galagininae (p. 542).
               {                 {                  { Lorisinae (p. 545).
               { Lemuroidea      { Chiromyidae (p. 548).
               {  (p. 534)       { Tarsiidae (p. 550).
  PRIMATES     {                 { Anaptomorphidae (p. 552).
   (p. 533)    {                 { Chriacidae (p. 552).
               {                 { Megaladapididae (p. 554).
               {
               {                 { Hapalidae (p. 556).
               { Anthropoidea    { Cebidae (p. 557).
               {  (p. 554)       { Cercopithecidae (p. 562).
               {                 { Simiidae (p. 570).
               {                 { Hominidae (p. 585).

       *       *       *       *       *


{1}

CHAPTER I

INTRODUCTORY

The Mammalia form a group of vertebrated animals which roughly correspond
with what are termed in popular language "quadrupeds," or with the still
more vernacular terms of "beasts" or "animals." The name "Mammal" is
derived from the most salient characteristic of the group, _i.e._ the
possession of teats; but if the term were used in an absolutely strict
etymological sense, it could not include the Monotremes, which, though they
have mammary glands, have not fully-differentiated teats (see p. 16). There
are, however, as will be seen shortly, other characters which necessitate
the inclusion of these egg-laying quadrupeds within the class Mammalia.

The Mammalia are unquestionably the highest of the Vertebrata. This
statement, however, though generally acceptable, needs some explanation and
justification. "Highest" implies perfection, or, at any rate, relative
perfection. It might be said with perfect truth that a serpent is in its
way an example of perfection of structure: not incommoded with limbs it can
slip rapidly through the grass, swim like a fish, climb like a monkey, and
dart upon its prey with rapidity and accuracy. It is an example of an
extremely specialised reptile, the loss of the limbs being the most obvious
way in which it is specialised from more generalised reptilian types.
Specialisation in fact is often synonymous with degradation, and, this
being the case, implies a restricted life. On the other hand,
simplification is not always to be read as degeneration. The lower jaw, for
instance, of mammals has fewer bones in it than that of reptiles, and is
more concisely articulated to the skull; this implies greater efficiency
{2} as a biting organ. The term highest, however, includes increased
complexity as well as simplification, the two series of modifications being
interwoven to form a more efficient organism. It cannot be doubted that the
increased complexity of the brain of mammals raises them in the scale, as
does also the complex and delicately adjusted series of bonelets which form
the organ for the transmission of sound to the internal ear. The separation
of the cavity containing the lungs, and the investment of the partition so
formed with muscular fibres, renders the action of the lungs more
effective; and there are other instances among the Mammalia of greater
complexity of the various parts and organs of the body when compared with
lower forms, which help to justify the term "highest" generally applied to
these creatures.

Complexity and finish of structure are often accompanied by large size; and
the Mammalia are, on the whole, larger than any other Vertebrates, and also
contain the most colossal species. The huge Dinosaurs of the Mesozoic
epoch, though among the largest of animals, are exceeded by the Whales; and
the latter group includes the mightiest creature that exists or has ever
existed, the eighty-five-feet-long Sibbald's Rorqual. Confining ourselves
rigidly to facts, and avoiding all theorising on the possible relation
between complexity and nicety of build and the capacity for increase in
bulk, it is plain from the history of more than one group of mammals that
increase in bulk accompanies specialisation of structure. The huge
Dinocerata when compared with the ancestral _Pantolambda_ teach us this, as
do many similar examples. Within the mammalian group, as in the case of
other Vertebrates, difference of size has a certain rough correspondence
with difference of habitat. The Whales not only contain the largest of
animals, but their average size is great; so too with the equally aquatic
Sirenia and very aquatic Pinnipedia. Here the support offered by the water
and the consequent decreased need for muscular power to neutralise the
effects of gravity permit of an increase in bulk. Purely terrestrial
animals come next; and finally arboreal, and, still more, "flying" mammals
are of small size, since the maintenance of the position when moving and
feeding needs enormous muscular effort.

The Mammals are more easily to be separated from the Vertebrates lying
lower in the series than any of the latter are from each other in ascending
order. A large number of {3} characters might be used in addition to those
which will be made use of in the following brief catalogue of essential
mammalian features, were it not for the low-placed Monotremata on the one
hand and the highly specialised Whales on the other. Including those forms,
the Mammalia are to be distinguished from all other Vertebrates by the
following series of structural features, which will be expanded later into
a short disquisition upon the general structure of the Mammalia. The class
Mammalia may, in fact, be thus defined:--

Hair-clad Vertebrates, with cutaneous glands in the female, secreting milk
for the nourishment of the young. Skull without prefrontal, postfrontal,
quadrato-jugal, and some other bones, and with two occipital condyles
formed entirely by the exoccipitals. Lower jaw composed of dentary bone
only, articulating only with the squamosal. Ear bones a chain of three or
four separate bonelets. Cervical vertebrae sharply distinguished from the
dorsals, and if with free ribs, showing no transition between these and the
thoracic ribs. Brain with four optic lobes. Lungs and heart separated from
abdominal cavity by a muscular diaphragm. Heart with a single left aortic
arch. Red blood-corpuscles non-nucleate.

The following characters are also very nearly universal, and in any case
absolutely distinctive:--Cervical vertebrae, seven; vertebrae with
epiphyses. Ankle-joint "cruro-tarsal," _i.e._ between the leg and the
ankle, and not in the middle of the ankle.[1] Attachment of the pelvis to
the vertebral column pre-acetabular in position.

The Mammalia since they are hot-blooded creatures are more independent of
temperature than reptiles; they are thus found spread over a wider area of
the earth's surface. As however, though hot-blooded, they have not the
powers of locomotion possessed by birds, they are not quite so widely
distributed as are those animals. The Mammalia range up into the extreme
north, but, excepting only forms mainly aquatic, such as the Sea Lions, are
not known to occur on the Antarctic continent. With the exception of the
flying Bats, indigenous mammals are totally absent from New Zealand; and it
seems to be doubtful whether those supposed oceanic islands which have a
mammalian fauna are really {4} oceanic in origin. The continents and oceans
are peopled by rather over three thousand species of Mammalia, a number
which is considerably less than that of either birds or reptiles. It seems
clear that, so far at any rate as concerns the numbers of families and
genera, the mammalian fauna of to-day is less varied than it was during the
Mid-tertiary period, the heyday of mammalian life. It is rather remarkable
to contrast in this way the mammals and the birds. The two classes of the
animal kingdom seem to have come into being at about the same period; but
the birds either have reached their culminating point to-day, or have not
yet reached it. The Mammalia, on the other hand, multiplied to an
extraordinary extent during the Eocene and the Miocene periods, and have
since dwindled. The break is most marked at the close of the Pleistocene,
and may be in part due to the direct influence of man. At present man
exercises so enormous an effect, both directly and indirectly, that the
future history of the Mammalia is probably foreshadowed by the instances of
the White Rhinoceros and the Quagga. On the other hand, the economic
usefulness of the Mammalia is greater than that of any other animals; and
the next most important era in their history will be probably that of
domesticity and "preservation."

       *       *       *       *       *


{5}

CHAPTER II

STRUCTURE AND PRESENT DISTRIBUTION OF THE MAMMALIA

EXTERNAL FORM.--It would be quite impossible for any one to confuse any
other quadrupedal animal with a mammal. The body of a reptile is, as it
were, slung between its limbs, like the body of an eighteenth century
chariot between its four wheels; in the mammal the body is raised entirely
above, and is supported by, the four limbs. The axes of these limbs too, as
a general rule, are parallel with the vertical axis of the body of their
possessor. There is thus a greater perfection of the relations of the limbs
to the trunk from the point of view of a terrestrial creature, which has to
use those limbs for rapid movement. The same perfection in these relations
is to be seen, it should be observed, in such running forms among the lower
Vertebrata as the Birds and the Dinosaurs, where the actual angulation of
the limbs is as in the purely running Mammalia. These relations are of
course absolutely lost in the aquatic Cetacea, and not marked in various
burrowing creatures. The way in which the fore- and hind-limbs are
angulated is considerably different in the two cases. In the latter, which
are most used and, as it were, push on the anterior part of the body, the
femur has its lower end directed forwards, the tibia and the fibula project
backwards at the lower end, while the ankle and foot are again inclined in
the same direction as the femur. With the fore-limbs there is not this
regular alternation. The humerus is directed backwards, the fore-arm
forwards, and the hand still more forwards. This angulation seems to
facilitate movement, inasmuch as it is seen in even the Amphibia and the
lower Reptiles, in which, however, the differences between the fore- and
hind-limbs are less marked, {6} indicating therefore a less specialised
condition of the limbs. It is an interesting fact that the angulation of
the limbs is to some extent obliterated in very bulky creatures, and almost
entirely so in the elephants (see p. 217), which seem to need strong and
straight pillars for the due support of their huge bodies.

The alertness and general intellectual superiority of mammals to all
animals lying below them in the series (with the exception of the birds,
which are in their way almost on a level with the Mammalia) are seen by
their active and continuous movements. The lengthy periods of absolute
motionlessness, so familiar to everybody in such a creature as the
Crocodile, are unknown among the more typical Mammalia except indeed during
sleep. This mental condition is clearly shown by the proportionate
development of the external parts of all the organs of the higher senses.
The Mammalia as a rule have well-developed, often extremely large, flaps of
skin surrounding the entrance to the organ of hearing, often called "ears,"
but better termed "pinnae." These are provided with special muscles, and
can be often moved and in many directions. The nose is always, or nearly
always, very conspicuous by its naked character; by the large surface,
often moist, which surrounds the nostrils; and again by the muscles, which
enable this tract of the integument to be moved at will. The eyes, perhaps,
are less marked in their predominance over the eyes of lower Vertebrates
than are the ears and nose; but they are provided as a rule with upper and
lower eyelids, as well as by a nictitating membrane as in lower
Vertebrates. The apparent predominance of the senses of smell and hearing
over that of sight appears to be marked in the Mammalia, and may account
for their diversity of voice as well as of odour, and for the general
sameness of coloration which distinguishes this group from the
brilliantly-coloured birds and reptiles. The head, too, which bears these
organs of special sense, is more obviously marked out from the neck and
body than is the case with the duller creatures occupying the lower
branches of the Vertebrate stem.

[Illustration]

FIG. 1.--A, Section of human skin. _Co_, Dermis; _D_, sebaceous glands;
_F_, fat in dermis; _G_, vessels in dermis; _GP_, vascular papillae; _H_,
hair; _N_, nerves in dermis; _NP_, nervous papillae; _Sc_, horny layer of
epidermis; _SD_, sweat gland; _SD_^1, duct of sweat gland; _SM_, Malpighian
layer. B, Longitudinal section through a hair (diagrammatic). _Ap_, Band of
muscular fibres inserted into the hair-follicle; _Co_, corium (dermis);
_F_, external longitudinal; _F_^1, internal circular, fibrous layer of
follicle; _Ft_, fatty tissue in the dermis; _GH_, hyaline membrane between
the root-sheath and the follicle; _HBD_, sebaceous gland; _HP_,
hair-papilla with vessels in its interior; _M_, medullary substance (pith)
of the hair; _O_, cuticle of root-sheath; _R_, cortical layer; _Sc_, horny
layer of epidermis; _Sch_, Hair shaft; _SM_, Malpighian layer of epidermis;
_WS_, _WS_^1, outer and inner layers of root-sheath. (From Wiedersheim's
_Comparative Anatomy_.)

[Illustration]

THE HAIR.--The Mammalia are absolutely distinguished from all other
Vertebrates (or, for the matter of that, Invertebrates) by the possession
of hair. To define a mammal as a Vertebrate with hair would be an entirely
exclusive definition; even in the smooth Whales a few hairs at least are
present, which may be {7} reduced to as few as two bristles on the lips.
The term "hair," however, is apt to be somewhat loosely applied; it has
been made use of to describe, for example, the slender processes of the
chitinous skin of the Crustacea. It will be necessary, therefore, to enter
into the microscopical structure and development of the mammalian hair.
Hair is found in every mammal. The first appearance of a hair is a slight
thickening of the stratum Malpighii of the epidermis, the cells taking part
in this being {8} elongated and converging slightly above and below. Dr.
Maurer has called attention to the remarkable likeness between the
embryonic hair when at this stage and the simple sense-organs of lower
Vertebrates. Later there is formed below this a denser aggregation of the
corium, which ultimately becomes the papilla of the hair. This is the
apparent homologue of the first formed part of a feather, which projects as
a papilla before the epidermis has undergone any modification. Hence there
is from the very first a difference between feathers and hairs--a
difference which must be carefully borne in mind, especially when we
consider the strong superficial resemblance between hairs and the simple
barbless feathers. Still later the knob of epidermic cells becomes
depressed into a tubular structure, which is lined with cells also derived
from the stratum Malpighii, but is filled with a continuation of the more
superficial cells of the epidermis. This is the hair-follicle, and from the
epidermic cells arises the hair by direct metamorphosis of those cells;
there is no excretion of the hair by the cells, but the cells become the
hair. From the hair-follicle also grows out a pair of sebaceous glands,
which serve to keep the fully-formed hair moist.

[Illustration]

FIG. 2.--Four diagrams of stages in the development of a hair. A, Earliest
stage in one of those mammals in which the dermal papilla appears first; B,
C, D, three stages in the development of the hair in the human embryo.
_blb_, Hair-bulb; _crn_, horny layer of the epidermis; _foll_,
hair-follicle; _grm_, hair-germ; _h_, hair, in D, projecting on the
surface; _muc_, Malpighian layer of epidermis; _pp_, dermal papilla; _seb_,
developing sebaceous glands; _sh.1_, _sh.2_, inner and outer root-sheaths.
(After Hertwig.)

Dr. Meijerle[2] has lately described in some detail the {9} particular
arrangement of the individual hairs among mammals; they are not by any
manner of means scattered without order, but show a definite and regular
arrangement, which varies with the animal. For instance, in an American
Monkey (_Midas_), the hairs arise in threes--three hairs of equal size
springing from the epidermis close together; in the Paca (_Coelogenys_)
there are in each group three stout hairs alternating with three slender
hairs. In some forms a number of hairs spring from a common point: in the
Jerboa (_Dipus_) twelve or thirteen arise from a single hole; in _Ursus
arctos_ there is the same general plan, but there is one stout hair and
four or five slender ones. There are numerous other complications and
modifications, but the facts, although interesting, do not appear to throw
any light upon the mutual affinities of the animals. Allied forms may have
a very different arrangement, while in forms which have no near
relationship the plan may be very similar, as is shown by the examples
cited from Dr. Meijerle's paper. The groups of hairs, moreover, have
themselves a definite placing, which the same anatomist has compared with
the disposition of the bundles of hairs behind and between the scales of
the Armadillo, and which has led him to the view that the ancestors of
mammals were scaly creatures--a view also supported by Professor Max
Weber,[3]and not in itself unreasonable when we consider the numerous
points of affinity between the primitive Mammalia and certain extinct forms
of reptiles.[4]

The hairs are greatly modified in form in different mammals and in
different parts of their bodies. It is very commonly the case that a soft
under-fur can be distinguished from the longer and coarser hairs, which to
some extent hide the latter. Thus the "sealskin" of commerce is the
under-fur of the _Otaria ursina_ of the North. The coarser hairs may be
further differentiated into bristles; these again into spines, such as
those of the Hedgehog and of the Porcupine. Again, the flattening and
agglutination of hairs seems to be responsible for the scales of the
_Manis_ {10} and for the horns of the _Rhinoceros_. It is a matter of
common knowledge that upon the head of various animals, _e.g._ the Domestic
Cat, long and sensitive hairs are developed, which are connected with the
terminations of nerves, and perform a sensory, probably tactile function.
These occur on the snout, above the eyes, and in the neighbourhood of the
ears. It is an interesting fact that a tuft of quite similar hairs occurs
on the hand of many mammals close to the wrist, which, at least in the case
of _Bassaricyon_, are connected with a strong branch from the arm-nerve.
These tufts also occur in Lemurs, in the Cat, various Rodents and
Marsupials, and are probably quite general in mammals who "feel" with their
fore-limbs;--in which, in fact, the fore-limbs are not exclusively running
organs. That the last remaining hairs of the Cetacea are found upon the
muzzle, is perhaps significant of the importance of these sensory bristles.
The entire absence of hairs is quite common in this order, although traces
of them are sometimes found in the embryo. The Sirenia, too, are
comparatively hairless, as are also many Ungulates. Whether the presence of
blubber in the former case and the existence of a very thick skin in the
latter animals are facts which have had anything to do with the
disappearance of hair or not, is a matter for further inquiry.

The intimate structure of the hair varies considerably. The variations
concern the form of the hair, which may be round in transverse section, or
so oval as to appear quite flat when the hair is examined in its entirety.
The substance of the hair is made up of a central medulla or pith with a
peripheral cortex; the latter is scaled, and the scales are often
imbricated and with prominent edges. The amount of the two constituents
also differs, and the cortex may be reduced to a series of bands
surrounding only tracts of the enclosed pith. In the hair is contained the
pigment to which the colour of mammals is chiefly due. Tracts of
brightly-coloured skin may exist, as in the Apes of certain genera; but
such structures are not general. The pigment of the hair seems to consist
of those pigmentary substances known as melanins. It is remarkable to find
such a uniform cause of coloration, when we consider the great variety of
feather-pigments found in birds. The variations of colour of the hair of
mammals are due to the unequal distribution of these brown pigments. There
are very few mammals which can {11} be called brightly coloured. The Bats
of the genus _Kerivoula_ have been compared to large butterflies, and some
of the Flying Squirrels have strongly-marked contrasts of reddish brown,
white, and yellow. The same may be said of the spines of certain
Porcupines. But we find in the hair no bright blues, greens, and reds such
as are common among birds.

There are certain general facts about the coloration of mammals which
require some notice here. Next to the usually sombre hues of these animals
the general absence of secondary sexual coloration is noteworthy. In but a
few cases among the Lemurs and Bats do we find any marked divergences in
hues between males and females. Secondary sexual characters in mammals are,
it is true, often exhibited by the great length of certain hair-tracts in
the male, such as the mane of the Lion, the throat- and leg-tufts of the
Barbary Sheep, and so forth; but apart from these, the secondary sexual
characters of mammals are chiefly shown in size, _e.g._ the Gorilla, or in
the presence of tusks, _e.g._ various Boars, or of horns, as in the Deer,
etc. The coloration of mammals frequently exhibits conspicuous patterns of
marking. These are in the form of longitudinal stripes, of cross-stripes,
or of spots; the latter may be "solid" spots, or broken up, as in the
Leopard and Jaguar, into groups of smaller spots arranged in a
rosette-fashion. We never find in mammals the complicated "eyes" and other
markings which occur in so many birds and in other lower Vertebrates. It is
important to note that in the Mammalia whose sense of sight is quite keen
there should be a practical absence of secondary sexual colours. As to the
relationship of the various forms of marking that do occur, it seems clear
that there has been a progression from a striped or spotted condition to
uniform coloration. For we find that many Deer have spotted young; that the
young Tapir of the New World is spotted, while its parents are uniform
blackish brown; the strongly-marked spotting of the young Puma contrasts
with the uniform brown of the adult; and the Lion cub, as every one knows,
is also spotted, the adult lioness showing considerable traces of the
spots.

The seasonal change in the colours of certain mammals is a subject upon
which much has been written. The extreme of this is seen in those
creatures, such as the Polar Hare and the Arctic Fox, which become entirely
blanched in the winter, recovering {12} their darker coat in the spring.
This is, however, only an extreme case of a change which is general. Most
animals get a thicker fur in winter and exchange it for a lighter one in
summer. And the hues of the coat change in correspondence.

GLANDS OF THE SKIN.--The great variety of integumental glands possessed by
the Mammalia distinguishes them from any group of lower Vertebrates. This
variability, however, only concerns the anatomical structure of the glands
in question. Histologically they are all of them apparently to be referred
to one of two types, the sudoriparous or sweat gland and the sebaceous
gland. Simple sweat and sebaceous glands are abundant in mammals, with but
a few exceptions. The structures that we are now concerned with are
agglomerations of these glands. The mammary glands will be treated of in
connexion with the marsupium; they are either masses of sweat glands, or of
sebaceous glands whose secretion has been converted into milk.

Many Carnivora possess glands opening to the exterior, near the anus, by a
large orifice. These secrete various odoriferous substances, of which the
well-known "civet" is an example. Other odoriferous glands are the musk
glands of the Musk-deer and of the Beaver; the suborbital gland of many
Antelopes; the dorsal gland of the Peccary, which has given the name of
_Dicotyles_ to the genus on account of its resemblance in form to a navel.
This gland may be seen to secrete a clear watery fluid. The Elephant has a
gland situated on the temple, which is said to secrete during certain
periods only, and to be a warning to leave the animal alone. Very
remarkable are the foot glands of certain species of _Rhinoceros_; they are
not universally present in those animals, and are therefore useful as
specific distinctions. On the back of the root of the tail in many Dogs are
similar glands. The Gentle Lemur (_Hapalemur_) has a peculiar gland upon
the arm, about the size of an almond, which in the male underlies a patch
of spiny outgrowths. In _Lemur varius_ is a hard patch of black skin which
may be the remnants of such a gland. It is thought that the callosities on
the legs of Horses and Asses are remnants of glands.

One of the most complex of these structures which has been examined
microscopically exists in the Marsupial _Myrmecobius_.[5] On the skin of
the anterior part of the chest, just in front of the {13} sternum, is a
naked patch of skin which is seen to be perforated by numerous pores.
Besides the ordinary sebaceous and sweat glands there are a series of
masses of glands, opening by larger orifices, which present the appearance
of groups of sebaceous glands, and are of a racemose character; but the
existence of muscular fibres in their coats seems to show that they should
be referred rather to the sudoriparous series. Beneath the integument is a
large compound tubular gland quite half an inch in diameter.

In _Didelphys dimidiata_ there is a precisely similar glandular area and
large underlying gland, the correspondence being remarkable in two
Marsupials so distant in geographical position and affinities. Even among
the Diprotodont genera there is something of the kind; for in _Dorcopsis
luctuosa_ and _D. muelleri_ is a collection of four unusually large
sebaceous follicles upon the throat, and in the Tree Kangaroo (_Dendrolagus
bennettii_) there is the same collection of enlarged hair-follicles, though
they are apparently somewhat reduced as compared with those of _Dorcopsis_.
These are of course a few examples out of many.

It seems to be possible that the functions of these various glands is at
least twofold. In the first place, they may serve, where predominant in one
sex, to attract the sexes together. In the second place, the glands may be
useful to enable a strayed animal of a gregarious species to regain the
herd. It is perfectly conceivable too that in other cases the glands may be
a protection, as they most undoubtedly are in the Skunk, from attacks. In
connexion with the first, and more especially the second, of the possible
uses of these glands, it is interesting to note that in purely terrestrial
creatures, such as the Rhinoceros, the glands are situated on the feet, and
would therefore taint the grass and herbage as the animal passed, and thus
leave a track for the benefit of its mate. The same may be said of the
rudimentary glands of Horses if they are really glands. The secretion of
the "crumen" of Antelopes is sometimes deposited deliberately by
_Oreotragus_ upon surrounding objects, a proceeding which would attain the
same end. One may even perhaps detect "mimicry" in the similar odours of
certain animals. Prey may be lured to their destruction, or enemies
frightened away. The defenceless Musk-deer may escape its foes by the
suggestion of the musky odour of a crocodile. It is at any rate perfectly
conceivable that the variety of odours among mammals may play a very {14}
important part in their life, and it is perhaps worthy of note that birds
with highly-variegated plumage are provided only with the uropygial gland,
while mammals with usually dull and similar coloration have a great variety
of skin glands. Scent is no doubt a sense of higher importance in mammals
than in birds. The subject is one which will bear further study.

NAILS AND CLAWS.--Except for the Cetacea (where rudiments have been found
in the foetus), the extremities of the fingers and of the toes of mammals
are covered by, or encased in, horny epidermic plates, known as nails,
claws, and hoofs.

The variety in the shape and development of these corneous sheaths to the
digits is highly characteristic of mammals as opposed to lower Vertebrates.
If we take extreme cases, such as the nail of the thumb in Man, the hoof of
a Horse, and the claw of a Cat, it is easy to distinguish the three kinds
of phalangeal horny coverings. But the differences become extinguished as
we pass from these to related types. The nail of the little finger in Man
approaches the claw-like form; and the hoofs of the Lama are almost claws
in the sharpness of their extremities. On the whole it may be said that
claws and hoofs embrace the bone which they cover, while nails lie only
upon its dorsal surface. The form of the distal phalanx which bears the
nail shows, however, two kinds of modification which do not support such a
classification. When those phalanges are clad with hoofs or covered by a
nail they end in a rounded and flattened termination. On the other hand,
when they bear a claw they are themselves sharpened at the extremity and
often grooved above.

THE MARSUPIUM.--It may appear to be unnecessary at this juncture to speak
of the marsupial pouch, which is so usually believed to be a characteristic
of the group Marsupialia. Rudiments of this structure have, however, been
recently discovered in the higher mammals, and, as Dr. Klaatsch[6] has
remarked, all researches into the "history of the mammals culminate in the
question whether the placental mammals pass through a marsupial stage or
not." We cannot, therefore, look upon the marsupial pouch as a matter
affecting only the Marsupials, though it is true that this organ is at
present functional only in them and in the Monotremata. {15}

[Illustration] FIG. 3.--_Echidna hystrix._ A, Lower surface of brooding
female; B; dissection showing a dorsal view of the pouch and mammary
glands; ++, the two tufts of hair in the lateral folds of the mammary pouch
from which the secretion flows, _b.m_, Pouch; _cl_, cloaca; _g.m_, groups
of mammary glands. (From Wiedersheim's _Comparative Anatomy_, after W.
Haacke.)

In the Marsupials the pouch shelters the young, which are born in an
exceedingly imperfect state, minute, nude, and blind, with a "larval" mouth
fitted only to grasp in a permanent fashion the teat, upon which they are
carefully fixed by the parent. But even later the pouch is made use of as a
temporary harbour of refuge: from the pouch of female Kangaroos at the
Zoological Gardens may frequently be observed to protrude the tail and
hind-legs of a young Kangaroo as big as a Cat, and perfectly well able to
take care of itself.

In the Monotremata (in _Echidna_) there is a deep fold of the skin which
lodges the unhatched egg, and into which the mammary glands open, one on
either side. This structure is only periodically developed, and arises from
two rudiments, one corresponding to each mammary area; but in the female
with eggs or young there is but a single deep depression, which occupies
the same region of the body as the marsupial pouch of the {16}
Marsupials.[7] It is usually held that this structure is not of precisely
the same morphological value as the pouch of the Marsupial; and the
difference is expressed by terming the one (that of _Echidna_) the mammary
pouch, and the other the marsupium. At first sight it may appear to be an
unnecessary refinement to separate two structures which have so many and
such obvious likenesses. It is not quite certain, however, that the
difference is not even more profound than later opinions seem to indicate.
The Monotremata not only have no teats, as has already been pointed out,
but the mammary glands themselves are of a perfectly different nature to
those of the higher mammals, including the Marsupials. There is therefore
no _a priori_ objection to the view that the accessory parts developed in
connexion with the mammary glands should also be different. The teat of the
higher Mammalia grows up round the area upon which the ducts of the mammary
glands open; it is a fold of skin which eventually assumes the cylindrical
form of the adult teat, and which includes the ducts of the milk glands. It
has been suggested that the two folds of skin which form the mammary pouch
of _Echidna_ are to be looked upon as the equivalent of the commencing teat
of the higher mammal.[8] In this case it is clear that the marsupial folds
of the Marsupial cannot correspond accurately with the apparently similar
folds of _Echidna_, because there are teats as well. It is the teats which
correspond to the marsupial folds of _Echidna_. This view is in apparent
contradiction to an interesting discovery in a specimen of a Phalanger by
Dr. Klaatsch.[9] This Marsupial, like most others, has a well-developed
marsupial pouch, in which the young are lodged at birth; but round two of
the teats is another distinct fold on either side, the outer wall of which
forms the general wall of the pouch. Dr. Klaatsch thinks that these smaller
and included pouches are the equivalents of the mammary pouches of
_Echidna_. They contain teats, but this comparison does not do away with
the validity of Gegenbaur's suggestion already referred to, because the
teats are (see above) {17} secondary. If this fact be fairly to be
interpreted in the sense which Dr. Klaatsch attaches to it, we have an
interesting case of the growth of a new organ out of and partly replacing
an old organ. In the Monotremes there is a pouch which facilitates or
performs both nutritive and protective functions; in the Phalanger these
two functions are carried on in separate pouches; finally, in other
Marsupials, there is a return to the undifferentiated state of affairs
found in the Monotremata, but with the help of a new organ not found in
them.

[Illustration]

FIG. 4.--Diagram of the development of the nipple (in vertical section). A,
Indifferent stage, glandular area flat; B, elevation of the glandular area
with the nipple; C, elevation of the periphery of the glandular area into
the false teat, _a_, Periphery of the glandular area; _b_, glandular area;
_gl_, glands. (From Gegenbaur.)

Though so characteristic of Marsupials, the marsupial pouch is not always
developed in them. It is present in all the Kangaroos, Wallabies, and
Wombats, in fact in the Diprotodonts. It is also present in a number of the
carnivorous Polyprotodont Marsupials; but in _Phascologale_ it is only
present in rudiment, and in _Myrmecobius_ it is entirely obsolete. In the
American Opossums the state of the pouch is variable. "Generally absent,
sometimes merely composed of two lateral folds of skin separate at each
end, rarely complete," is Mr. Thomas' summary in his definition of the
family Didelphyidae.[10] Another curious feature of the pouch in the
Marsupials is the variability in the position of the mouth of the pouch: in
all the Diprotodonts it looks forward; but in many Polyprotodonts it looks
backward. This, however, has some connexion with the habitual attitude of
the possessor: in the Kangaroo, leaping along on its hind-legs, it is
requisite that the pouch should open forwards; but in the dog-like
Thylacine, going on all fours, the fact that the pouch {18} opens backwards
is less disadvantageous to the contained young.

The male Thylacine has a pouch which is quite or very nearly as well formed
as in the female. There are also rudiments of a pouch in the male foetuses
of many Marsupials, especially of those belonging to the Polyprotodont
section of the order, though these rudiments are by no means confined to
that subdivision. Up to so late a period as the age of four months (length
19.8 cm.) the male _Dasyurus ursinus_ has a pouch.

We have now to consider the interesting series of facts relative to the
permanence--in a rudimentary condition it is true--of the mammary pouch in
the higher Mammalia, facts which seem to be an additional proof that they
have been derived from an ancestor in which the pouch was an organ of
functional importance. The first definite proof of the occurrence of a
pouch in any mammal not a Marsupial or a Monotreme was made by Malkmus, who
found this structure in a Sheep. It seems, however, that the structures
found in the higher mammals are not always comparable to the marsupium of
the Marsupials, but sometimes to the mammary pouch of the Monotreme. That
the Marsupials are a side line, and not involved in the ancestry of the
Eutheria, is an opinion which is at present widely held. At the same time
it is reasonable to suppose that the original stock lying between the
Prototheria and the Metatheria, whence the latter and the Eutheria have
arisen, preserved both the mammary pouch of the lower mammal and the
marsupium of the further-developed stage, as does _Phalangista_
occasionally at the present day. Hence to find remnants of both structures
in existing mammals would not so incredible. This is what Dr. Klaatsch
believes to be the case. In certain Ungulates, including two species of
Antelope, Dr. Klaatsch found very considerable rudiments of folds provided
with unstriated muscular fibre; there were in the adult _Cervicapra
isabellina_ a pair of pouches, one on each side, and a rudiment of a second
on either side; possibly this multiplication of the pouches has relation to
the number of young. That there is more than one pouch makes a comparison
with the mammary pouch rather than with the marsupium probable. The
Ungulate teat, it must be remembered (see p. 16), is a secondary teat;
hence there is no difficulty in the comparison from this point of view. A
pouch containing a primary {19} teat would of course be absolutely
incomparable with a mammary pouch, because in that case the wall of the
teat itself would be the pouch.

Mammals belonging to quite different Orders show traces more or less marked
of a marsupium. In young Dogs the teats are borne upon an area where the
skin is thinner, the covering of hair less dense than elsewhere--all points
of resemblance to the inside of the pouch of a Marsupial; in addition to
this there are traces of the sphincter marsupii muscle. In other Carnivora
there are similar vestiges. In _Lemur catta_ a more complete rudiment of a
marsupial pouch is to be met with. In this Lemur the teats are both
inguinal and pectoral; the skin in these regions is thin and but slightly
hairy, and extends forwards as two bands of the same thinness and
smoothness on each side of the densely hairy skin covering the sternum.
This area is sharply separated from the rest of the integument by a fold
which runs parallel to the longitudinal axis of the body, and can be
comparable with nothing save the rudiment of the marsupial fold.

One is tempted to wonder how far the habit which certain Lemurs have of
carrying their young across the abdomen with the tail wrapped round the
body of the mother is a reminiscence of a marsupial pouch.

SKELETON.

The skeleton of the Mammalia consists almost solely of the endoskeleton. It
is only among the Edentata that an exoskeleton of bony plates in the skin
is met with. As in other Vertebrates, the skeleton is divisible into an
axial portion, the skull and vertebral column, and an appendicular
skeleton, that of the limbs. The bones of mammals are well ossified, and in
the adult there are but few and small tracts of cartilage left.

VERTEBRAL COLUMN.--The vertebral column of the mammals, like that of the
higher Vertebrata, consists of a number of separate and fully-ossified
vertebrae.

The constitution of a vertebra upon which all the usual processes are
marked is as follows:--There is first of all the body or centrum of the
vertebra, a massive piece of bone shaped like a disc or a cylinder. The
centra of contiguous vertebrae {20} are separated by a certain amount of
fibrous tissue forming the intervertebral disc, and the apposed surfaces of
the centra are as a rule nearly flat. In this last feature, and in the
important fact that the centra are ossified from three distinct centres,
the anterior and posterior pieces ("epiphyses") remaining distinct for a
time, even for a long time (as in the Whales), the centra in the mammals
differ from those of reptiles and birds. The epiphyses are not found
throughout the vertebral column of the lowly-organised Monotremata, and
they do not appear to exist in the Sirenia.

[Illustration]

[Illustration]

FIG. 5.--Anterior surface of Human thoracic vertebra (fourth), × 2/3. _az_,
Anterior zygapophysis; _c_, body or centrum; _l_, lamina, and _p_, pedicle,
of the neural arch; _nc_, neural canal; _t_, transverse process. (From
Flower's _Osteology of the Mammalia_.)

FIG. 6.--Side view of first lumbar vertebra of Dog (_Canis familiaris_). ×
¾. _a_, Anapophysis; _az_, anterior zygapophysis; _m_, metapophysis; _pz_,
posterior zygapophysis; _s_, spinous process; _t_, transverse process.
(From Flower's _Osteology_.)

From each side of the centrum on the dorsal side arises a process of bone
which meets its fellow in the middle line above, and is from there often
prolonged into a spine. A canal is thus formed which lodges the spinal
cord. This arch of bone is known as the neural arch, and the dorsal process
of the same as the spinous process. The sides of the neural arch bear oval
facets, by which successive vertebrae articulate with one another: those
situated anteriorly are the anterior zygapophyses, while those on the
posterior aspect of the arch are the posterior zygapophyses; these
articular facets do not exist in the tail-region of many mammals, _e.g._
Whales.

In addition to the dorsal median spinous process of the {21} vertebra there
may be a ventral median process, arising of course from the centrum, termed
the hypapophysis.

From the sides of the neural arch, or from the centrum itself, there is
commonly a longer or shorter process on each side, known as the transverse
process. This is sometimes formed of two distinct processes, one above the
other; in such cases the upper part is called a diapophysis, the lower a
parapophysis.

The neural arch may also bear other lateral processes, of which one
directed forwards is the metapophysis, the other directed backwards the
anapophysis.

The series of bones which constitute the vertebral column can be divided
into regions. It is possible to recognise cervical, dorsal, lumbar, sacral,
and caudal vertebrae. In the case of animals with only rudimentary
hind-limbs, such as the Whales, there is no recognisable sacral region. The
neck or cervical vertebrae are nearly always seven in number. The
well-known exceptions are the Manatee, where there are six, and certain
Sloths, where there are six, eight, or nine. These rare exceptions only
accentuate the very remarkable constancy in number, which is very
distinctive of the mammals as compared with lower Vertebrata. There are of
course abnormalities, the last cervical, and sometimes the last two,
assuming the characters of the ensuing dorsals, by developing a more or
less complete rib. There are also recorded examples of _Bradypus_, in which
the number of cervicals is increased to ten. The characteristics, then, of
the cervical vertebrae are, in the first place, that they do not normally
bear free ribs, and that there is a break as a rule between the last
cervical and the first dorsal on this account. In birds, for example, the
cervicals, differing in number in different families and genera, gradually
approach the dorsals by the gradually lengthening ribs. The transverse
processes of the vertebrae are commonly perforated by a canal for the
vertebral artery, and are bifid at their extremities. In some Ungulates
these vertebrae, moreover, approximate to the vertebrae of lower Vertebrata
in the fact that there are ball and socket joints between the centra,
instead of only the fibrous discs of the remaining vertebrae.

The first two vertebrae of the series are always very different from those
which follow. The first is termed the {22} atlas, and articulates with the
skull. The most remarkable fact about this bone (shared, however, by lower
Vertebrates) is that its centrum is detached from it and attached to the
next vertebra, in connexion with which it will be referred to immediately.
The whole bone thus gets a ring-like form, and the salient processes of
other vertebrae are but little developed, with the exception of the
transverse processes, which are wide and wing-like. In many Marsupials,
such as the Wombat and Kangaroo, the arch of the atlas is open below, there
being no centre of ossification. In others, such as _Thylacinus_, there is
a distinct nodule of bone in this situation not concrescent with the rest
of the arch.

[Illustration]

[Illustration]

FIG. 7.--Human atlas (young), showing development. × ¾. _as_, Articular
surface for occiput; _g_, groove for first spinal nerve and vertebral
artery; _i a_, inferior arch; _t_, transverse process. (From Flower's
_Osteology_.)

FIG. 8.--Inferior surface of atlas of Dog. × ½. _sn_, Foramen for first
spinal nerve; _v_, vertebrarterial canal. (From Flower's _Osteology_.)

[Illustration]

FIG. 9.--Atlas of Kangaroo.... (From Parker and Haswell's _Zoology_.)

The second vertebra, which is known as the axis or epistropheus, is a
compound structure, the anterior "odontoid process," which fits into the
ring of the atlas, being in reality the detached centrum of that
vertebra.[11] It is a curious fact about that process that it has
independently become spoon-shaped in two divisions of Ungulates; that it
has become so seems to be shown by the fact that in the earlier types of
both it has the simple peg-like form, which is the prevailing form. The
cervical {23} vertebrae are occasionally wholly (Right Whales) or partially
(many Whales, Jerboa, certain Edentates) welded into a combined mass.
Indications of this have even been recorded in the human subject.

[Illustration]

[Illustration]

FIG. 10.--Side view of axis of Dog. × 2/3. _o_, Odontoid process; _pz_,
posterior zygapophysis; _s_, spinous process; _t_, transverse process; _v_,
vertebrarterial canal. (From Flower's _Osteology_.)

FIG. 11.--Anterior surface of axis of Red Deer. × 2/3. _o_, Odontoid
process; _pz_, posterior zygapophysis; _sn_, foramen for second spinal
nerve. (From Flower's _Osteology_.)

The dorsal vertebrae vary greatly in number: nine (_Hyperoodon_) seems to
be the lowest number existing normally; while there may be as many as
nineteen, as in _Centetes_, or twenty-two, as in _Hyrax_. These vertebrae
are to be defined by the fact that they carry ribs, and the first one or
two lumbars are often "converted into" dorsals by the appearance of a small
supernumerary rib. The spinous processes of these vertebrae are commonly
long, and sometimes very long. It is only among the Glyptodons that any of
these vertebrae are fused together into a mass.

The lumbar vertebrae, which follow the dorsal, vary greatly in number.
There are as few as two in the whale _Neobalaena_, as many as seventeen in
_Tursiops_; this group, the Cetacea, contains the extremes. Nine lumbars
are found in the Lemurs _Indris_ and _Loris_. As a rule the number of
lumbars is to some extent dependent upon that of the dorsals. It often
happens that the number of thoraco-lumbar vertebrae is constant for a given
group. Thus the Artiodactyles have nineteen of these vertebrae, and the
Perissodactyles as a rule twenty-three. A greater number of dorsals implies
a smaller number of lumbars, and of course _vice versa_. The existence of a
sacral region formed of a {24} number of vertebrae fused together and
supported by the pelvic girdle is characteristic of the mammals, but is not
found in the Cetacea and the Sirenia, where functional hind-limbs are
wanting. Strictly speaking, the sacrum is limited to the two or three
vertebrae whose expanded transverse processes meet the ilia. But to these
are or may be added a variable number of vertebrae withdrawn from both the
lumbar and the caudal series, which unite with each other to form the
massive piece of bone which constitutes the sacrum of the adult.

[Illustration]

[Illustration]

FIG. 12.--_Lepus cuniculus_. Innominate bones and sacrum, ventral aspect.
_acet_, Acetabulum; _il_, ilium; _isch_, ischium; _obt_, obturator foramen;
pub, pubis; _sacr_, sacrum; _sy_, symphysis. (From Parker and Haswell's
_Zoology_.)

FIG. 13.--Anterior surface of fourth caudal vertebra of Porpoise (_Phocoena
communis_), × ½. _h_, Chevron bone; _m_, metapophysis; _s_, spinous
process; _t_, transverse process. (From Flower's _Osteology_.)

The caudal vertebrae complete the series. They begin in as fully developed
a condition as the lumbars, with well-marked transverse processes, etc.;
but they end as no more than centra, from which sometimes tiny outgrowths
represent in a rudimentary way the neural arches, etc. Very often the
caudal vertebrae are furnished with ventral, generally [12]-shaped,
appendages, the chevron bones or intercentra.[13] These are {25}
particularly conspicuous in the Whales and in the Edentates. In the former
group the occurrence of the first intercentrum serves to mark the
separation of the caudal from the lumbar series. The number of caudals
varies from three in Man--and those quite rudimentary--to nearly fifty in
_Manis macrura_ and _Microgale longicaudata_.

[Illustration]

FIG. 14.--Lateral view of skull of a Dog. _C.occ_, Occipital condyle; _F_,
frontal; _F.inf_, infra-orbital foramen; _Jg_, jugal; _Jm_, premaxilla;
_L_, lachrymal; _M_, maxilla; _Maud_, external auditory meatus; _Md_,
mandible; _N_, nasal; _P_, parietal; _Pal_, palatine; _Pjt_, process of
squamosal; _Pt_, pterygoid; _Sph_, alisphenoid; _Sq_, squamosal; _Sq.occ_,
supraoccipital; _T_, tympanic. (From Wiedersheim's _Comparative Anatomy_.)

THE SKULL.--The skull in the Mammalia differs from that of the lower
Vertebrata in a number of important features, which will be enumerated in
the following brief sketch of its structure. In the first place, the skull
is a more consolidated whole than in reptiles; the number of elements
entering into its formation is less, and they are on the whole more firmly
welded together than in Vertebrates standing below the Mammalia in the
series. Thus in the cranial region the post- and pre-frontals, the
post-orbitals and the supra-orbitals have disappeared, though now and again
we are reminded of their occurrence in the ancestors of the Mammalia by a
separate ossification corresponding to some of the bones. Nowhere is this
consolidation seen with greater clearness than in the lower jaw. That bone,
or rather each half of it, is in mammals formed of one bone, the dentary
(to which occasionally, as it appears, a separate mento-Meckelian {26}
ossification may be added). The angular, splenial, and all the other
elements of the reptilian jaw have vanished, though the numerous points
from which the mammalian dentary ossifies is a reminiscence of a former
state of affairs; and here again an occasional continuance of the
separation is preserved, as the case observed by Professor Albrecht of a
separate supra-angular bone in a Rorqual attests. Among other reptilian
bones that are not to be found in the mammalian skull are the
basipterygoids, quadrato-jugal, and supratemporal. A few of these bones,
however, though no longer traceable in the adult skull save in cases of
what we term abnormalities, do find their representatives in the foetal
skull. Professor Parker, for example, has described a supra-orbital in the
embryo Hedgehog; a supratemporal also appears to be occasionally
independent.

[Illustration]

FIG. 15.--Head of a Human embryo of the fourth month. Dissected to show the
auditory ossicles, tympanic ring, and Meckel's cartilage, with the hyoid
and thyroid apparatus. All these parts are delineated on a larger scale
than the rest of the skull. _an_, Tympanic ring; _b.hy_, basihyal element;
_hy_, so-called hyoid bone; _in_, incus; _md_, bony mandible; _ml_,
malleus; _st_, stapes; _tp_, tympanum; _tr_, trachea; I. (_mk_), first
skeletal (mandibular) arch (Meckel's cartilage); II. second skeletal
(hyoid) arch; III. third (first branchial) arch; IV. V. fourth and fifth
arches (thyroid cartilage). (From Wiedersheim's _Structure of Man_.)

In the mode of the articulation of the lower jaw to the skull the Mammalia
apparently, perhaps really, differ from other Vertebrates. In the Amphibia
and Reptilia, with which groups alone any comparisons are profitable, the
lower jaw articulates by means of a quadrate bone, which may be movably or
firmly attached to the skull. In the mammals the articulation of the lower
jaw is with the squamosal. The nature of this articulation is one of the
most debated points in comparative anatomy. Seeing that Professor
Kingsley[14] in the most recent contribution to the subject quotes no less
than fifty-two different views, many of which are more or less convergent,
it will be obvious that in a work like the present the matter cannot be
treated exhaustively. As, however, Professor Kingsley justly says that "no
single bone occupies a more important position in the discussion of the
origin of the Mammalia than does the quadrate," and with equal justice adds
that "upon the answer given as to its fate in this group depends, in large
measure, the broader problem of the phylogeny of the Mammalia," it becomes,
or indeed has long been, a matter which cannot be ignored in any work
dealing with the mammals. A simple view, due to the late Dr. Baur and to
Professor Dollo, commends itself at first sight as meeting the case. The
last-named author holds, or held, that in all the higher Vertebrates it is
at least on _a priori_ grounds likely that two such characteristically
vertebrate features as the lower jaw and the chain of bones bringing the
outer world {27} into communication with the internal organ of hearing
would be homologous throughout the series. He believed, therefore, that the
entire chain of ossicula auditus in the mammal is equal to the columella of
the reptile, since their relations are the same to the tympanum on the one
hand and to the foramen ovale on the other; and that the lower jaw
articulates in the same way in both. It follows, therefore, that the
glenoid part of the squamosal must be the quadrate which has become
ankylosed with it after the fashion of concentration in the mammalian skull
that has already been referred to. The fact that occasionally the glenoid
part of the squamosal is a separate bone[15] appeared to confirm this way
of looking at the {28} matter. But the hall-mark of truth is not always
simplicity; indeed the converse appears to be frequently the case. And on
the whole this view does not commend itself to zoologists at present. For
it must be borne in mind that the lower jaw of the mammal is not the
precise equivalent of that of the reptiles. Apart from the membrane bones,
which may be collectively the equivalents of the dentary of the mammal,
there is the cartilaginous articular bone to be considered, which forms the
connexion between the rest of the jaw and the quadrate in reptiles. Even in
the Anomodontia, whose relations to the Mammalia are considered elsewhere,
there is this bone. But in these reptiles the articular bone articulates
not only with the quadrate, but also to a large extent with the squamosal,
the quadrate shrinking in size and developing processes which give to it
very much the look of either the incus or the malleus of the mammalian ear.
In fact it seems on the whole to fit in with the views of the majority, as
well as with a fair interpretation of the facts of embryology, to consider
that the chain of ear bones in the mammal is not the equivalent of the
columella of the reptile, but that the stapes of the mammal is the
columella, and that the articulare is represented by the malleus and the
quadrate by the incus. It is very interesting to note this entire change of
function in the bones in question. Bones which in the reptile serve as a
means of attachment of the lower jaw to the skull are used in the mammal to
convey the waves of sound from the tympanum of the ear to the internal
organ of hearing.

Another important and diagnostic feature in the mammalian skull is that the
first vertebra of the vertebral column always articulates with two separate
occipital condyles, which are borne by the exoccipital bones and formed
mainly though not entirely by them. Certain Anomodontia form the nearest
approach to the mammals in this particular. The two condyles of Amphibia
are purely exoccipital in origin.

In the Mammalia, unlike what is found in lower Vertebrates (but here again
the Anomodontia form at least a partial exception), the jugal arch does not
connect the face with the quadrate, for, as already said, that bone does
not exist, in the Sauropsidan form, in mammals. This arch passes from the
squamosal to the maxillary, and has but one separate bone in addition to
those two, viz. the jugal or malar. {29}

[Illustration]

FIG. 16.--Under surface of the cranium of a Dog. × ½. _apf_, Anterior
palatine foramen; _as_, posterior opening of alisphenoid canal; _AS_,
alisphenoid; _BO_, basioccipital; _BS_, basisphenoid; _cf_, condylar
foramen; _eam_, external auditory meatus; _Ex.O_, exoccipital; _flm_,
foramen lacerum medium; _flp_, foramen lacerum posterius; _fm_, foramen
magnum; _fo_, foramen ovale; _fr_, foramen rotundum; _Fr_, frontal; _gf_,
glenoid fossa; _gp_, post-glenoid process; _Ma_, malar; _Mx_, maxilla;
_oc_, occipital condyle; _op_, optic foramen; _Per_, mastoid portion of
periotic; _pgf_, post-glenoid fossa; _Pl_, palatine; _PMx_, premaxilla;
_pp_, paroccipital process; _ppf_, posterior palatine foramen; _PS_,
presphenoid; _Pt_, pterygoid; _sf_, sphenoidal fissure or foramen lacerum
anterius; _sm_, stylomastoid foramen; _SO_, supraoccipital; _Sq_, zygomatic
process of squamosal; _Ty_, tympanic bulla; _Vo_, vomer. (From Flower's
_Osteology_.)

In connexion with the elaboration of the chain of auditory ossicles it is
very usual for mammals to possess a thin inflated bone, sometimes partly or
entirely formed out of the tympanic bone, and known as the tympanic bulla.
Whether this structure is thin and inflated or thick and depressed in form
it is characteristic of the mammals, and does not occur below them in the
series. But it is not present in all mammals. It is absent, for example, in
the Monotremes. When it is present it is sometimes formed from other bones,
as, for instance, from the alisphenoids. The tympanic ring has been held to
be the equivalent of the quadrate. It is more probably the
quadrato-jugal.[16]

[Illustration]

FIG. 17.--A, First thoracic skeletal segment for comparison with B, fifth
cervical vertebra (Man), _b.v._ Body of vertebra; _c_, first thoracic rib;
_c_', cervical rib (which has become united with the transverse process,
_tr_), the two enclosing the costo-transverse foramen (_f.c.t_); _st_,
sternum; _zy_, articular process of the arch (zygapophysis). (From
Wiedersheim's _Structure of Man_.)

RIBS.--All mammals are furnished with ribs, of which the number of pairs
differs considerably from group to group, or it may be even from species to
species. The ribs are attached as a rule by two heads, of which one, the
capitulum, arises as a rule between two centra of successive vertebrae. The
other, the tuberculum, springs from the transverse process. Only in the
Monotremes {30} are there ribs with but one, the capitular, head. In the
posterior part of the series the two heads often gradually coalesce, so
that there comes to be but one, the capitular, head. The Whales also, at
least the Whalebone Whales, are exceptional in possessing but one head to
the ribs, which is the capitular. The first rib joins the sternum below,
and a variable number after this have the same attachment. There are always
a number of ribs, sometimes called floating ribs, which have no sternal
attachment. In the Whalebone Whales it is the first rib alone which is so
attached. As a rule, to which the Whales mentioned are again an exception,
the rib is divided into at least two regions--the vertebral portion which
is always ossified, and the sternal moiety which is usually cartilaginous.
This is, however, often very short in the first rib. They are, however,
ossified in the Armadillos and in some other animals. Between the vertebral
and sternal portions an intermediate tract is separated off and ossified in
the Monotremata. The ribs of existing mammals belong only to the dorsal
region of the vertebral column, but there are traces of lumbar ribs and
also of cervical ribs. In the Monotremata, indeed, these latter {31} are
persistently free for a very long period, and in some cases never become
ankylosed with their vertebrae. But it should be noted that in this group
there is no approximation to the state of affairs which exists in many
lower Vertebrates, where there is a gradual transition between the ribs of
the cervical and those of the dorsal region of the vertebral column; for
that of the seventh ribs in Monotremes is smaller than those which precede
it.

[Illustration]

[Illustration]

FIG. 18.--Sternum and sternal ribs of the Common Mole (_Talpa europaea_),
with the clavicles (_cl_) and humeri (_H_); _M_, manubrium sterni. Nat.
size. (From Flower's _Osteology_.)

FIG. 19.--Sternum of the Pig (_Sus scrofa_). × ¼. _ms_, Mesosternum; _ps_,
presternum; _xs_, xiphisternum. (From Flower's _Osteology_.)

THE STERNUM.--All the Mammalia so far as is known possess a sternum. This
is the bone, or series of bones (sternebrae), which lies upon the ventral
surface of the chest, and to which the ribs are attached below. The
development of the sternum has been shown to take place from the fusion of
the ribs below into two lateral bands, one on each side; the approximation
of these bands forms the single and unpaired sternum of most mammals. Very
considerable traces, however, of the paired state of the sternal bones
often exist; thus in the Sperm Whale the first piece of the sternum is
divided into two by a longitudinal division, and the second piece is
longitudinally grooved. The development of the sternum out of the fused
ends of ribs is shown in a more complete condition in some species of
_Manis_ than in many other mammals. Thus in _M. tricuspis_ the last ribs of
those which are attached to the sternum are completely fused together into
a single piece on each side.[17] As a general rule the last ribs which come
into relation with the sternum do so only in an imperfect way, being simply
firmly attached at their sides to, but not fused with, the last ribs which
are definitely articulated with the sternum. Contrary to what is found in
lower {32} Vertebrates, the sternum of the Mammalia consists of a series of
pieces, as many as eight or nine or even sixteen in _Choloepus_, of which
the first is called the manubrium sterni, and the last the ensiform
cartilage, xiphisternum, or xiphoid process. The latter often remains
largely cartilaginous throughout life; in fact this is generally but not
universally the case with that part of the breastbone. The most
extraordinary modification of the xiphoid process is seen in the African
species of the genus _Manis_, where it diverges into two long cartilages,
which run back to the pelvis and then, curving round, run forwards and fuse
together in the middle line anteriorly. These processes serve for the
attachment of certain tongue-muscles. They were looked upon by Professor
Parker as the equivalents of the "abdominal ribs" of reptiles elsewhere
non-existent among mammals. This view is not, however, usually held. The
manubrium sterni is often keeled in the middle line below; this is so with
the Bats, which thus approach the birds, and probably for the same reason,
i.e. the need of an enlarged origin for the pectoral muscle, which is
concerned in the movements of flight. In many forms this part of the
sternum is much broader than the pieces which follow; this is so with the
Viscacha. In the Pig the precise reverse is seen, the manubrium being
narrower than the rest of the sternal bonelets. It will be noticed,
however, that in this and similar cases there are no clavicles. Ribs are
attached between the successive pieces of the sternum. When the sternum is
reduced, as it is in the Cetacea and in the Sirenia, it is the intermediate
part of the series of bones which becomes abbreviated or vanishes. The
Sperm Whale has only a manubrium sterni and a following piece belonging to
the mesosternum. It is fair to say that the xiphoid process and the rest of
the sternum have disappeared, since among the Toothed Whales a progressive
shortening of the sternum can be seen. In the Whalebone Whales the sternum
is still further reduced; the manubrium is alone left, and to it are
attached but a single pair of ribs. In _Balaena_, however, a rudimentary
{33} piece, apparently comparable to a xiphoid process, has been detected.

[Illustration]

[Illustration]

FIG. 20.--Sternum of Rudolphi's Whale (_Balaenoptera borealis_), showing
its relation to the inferior extremities of the first pair of ribs. × 1/10.
(From Flower's _Osteology_.)

FIG. 21.--Sternum of a young Dugong (_Halicore indicus_). × ¼. From a
specimen in the Leyden Museum, _ps_, Presternum; _xs_, xiphisternum. (From
Flower's _Osteology_).

From the instances which have been described, as well as from the mode of
development of the sternum and from the number of free ribs, _i.e._ ribs
which are not attached to it, it would seem that the sternum has undergone
a considerable reduction in its size. This reduction may be possibly
accounted for by the need for respiratory activity, which is clearly
increased by a less-marked fixity of the walls of the thoracic cavity. In
the case of the Whales one can hardly help coming to that conclusion. The
arrangement in the Monotremata does not, however, point in the same
direction; for these animals are precisely like the higher Mammalia in the
reduction of the sternum and of the number of ribs which reach it.

[Illustration]

FIG. 22.--Shoulder girdle of Ornithorhynchus. _c_^1, _c_^2, _c_^3, First,
second, third ribs; _cl_, clavicle; _e.c_, epicoracoid; _es_' and _es_",
interclavicle (episternum); _m.c_, metacoracoid; _m.s_, manubrium sterni;
_sc_, scapula; _st_, sternebra. (From Wiedersheim's _Structure of Man_.)

[Illustration]

FIG. 23.--Episternum of an embryo Mole. (After A. Götte.) _cl_, Clavicle;
_es_', central portion of the episternum; _es_", lateral portion of the
same; _r.c_, costal ribs; _st_, sternum. (The figure was constructed from
two consecutive horizontal sections.) (From Wiedersheim's _Structure of
Man_.)

THE EPISTERNUM.--The Mammalia are as a rule to be distinguished from lower
Vertebrates by the absence of an episternum, or interclavicle as it is also
called. In the Monotremata, however, there is a large [18]-shaped bone
which does not overlie the sternum as in reptiles, but is anterior to it.
The relations of this bone to the clavicles seem to leave no doubt that it
is the equivalent of the Lacertilian interclavicle or episternum. The
Monotremata are not, however, the only mammals in which this structure is
to be seen. The Mole in the embryonic condition is {34} provided with
pieces of bone which overlie the manubrium sterni and are attached to the
clavicles, and are no doubt to be regarded as the same structure. Probably
in many mammals the manubrium will be found to be partly made up of
corresponding rudiments. In any case, vestiges of an episternum in the
shape of two minute ossicles have been discovered in Man, lying in front of
the manubrium. They have been termed ossa suprasternalia. In Man and in the
Mole the paired nature of the episternum is clearly apparent. It has been
suggested that this structure in its entirety belongs to the clavicles,
just as the sternum belongs to the ribs; _i.e._ that it formed out of the
approximated and fused ends of the clavicles. Dr. Mivart[19] figured a good
many years since a pair of ossicles in _Mycetes_, lying in one case between
the ends of the clavicles and the manubrium sterni, and in another example
anterior to the ventral ends of the clavicles. Gegenbaur has figured a {35}
pair of similar bones in the Hamster.[20] It is possible that these are to
be referred to the same category. It has also been suggested that these
supposed episternal rudiments are the vestiges of a pair of cervical ribs.

[Illustration]

FIG. 24.--Episternal vestiges in Man. _cl_, Clavicle, sawn through; _es_,
"episternum" (sternoclavicular cartilage); _l_', interclavicular ligament;
_l_", costoclavicular ligament; _m.s_, manubrium sterni; _o.s_, ossa
suprasternalia; _r.c_, first rib; _st_, sternum. (From Wiedersheim's
_Structure of Man_.)

THE PECTORAL GIRDLE.--The skeleton by which the fore-limb is connected with
the trunk is known as the Pectoral Girdle. The main part of this girdle is
formed by the large scapula, or blade-bone as it is often termed. The
coracoidal elements will be dealt with later. The scapula is not firmly
connected with the backbone; it is attached merely by muscles, thus
presenting a great difference from the corresponding pelvic girdle. The
reason for this difference is not easy to understand. On the one hand it
may be pointed out that in all running animals at any rate there is a
greater need for the fixation in a particularly firm way of the hind-limbs;
but, again, in the climbing creatures both limbs would, one might suppose,
be bettered by a firm fixation. It must be remembered, however, that in the
latter case the same result is at least partly brought about by a
well-developed clavicle, which fixes the girdle to the sternum and so to
the vertebral column by means of the ribs.

Broadly speaking, too, the fore-limbs require a greater freedom and variety
of movement than the hind-limbs, which are supports {36} for or serve to
push along the rapidly-moving body. Stronger fixation is therefore a
greater necessity posteriorly than anteriorly. In any case, whatever the
explanation, this important difference exists.

[Illustration]

FIG. 25.--Right scapula of Dog (_Canis familiaris_). × ¼. _a_, Acromion;
_af_, prescapular fossa; _c_, coracoid; _cb_, coracoid or anterior border;
_css_, indicates the position of the coraco-scapular suture, obliterated in
adult animals by the complete ankylosis of the two bones; _gb_, glenoid or
posterior border; _gc_, glenoid cavity; _pf_, postscapular fossa; _s_,
spine; _ss_, suprascapular border. (From Flower's _Osteology_.)

[Illustration]

FIG. 26.--Right scapula of Red Deer (Cervus elaphus). × ¼. _a_, Acromion;
_af_, anterior or prescapular fossa; _c_, coracoid; _gc_, glenoid cavity;
_pf_, postscapular fossa; _ss_, partially ossified suprascapular border.
(From Flower's _Osteology_.)

The shoulder-blade of mammals is as a rule a much-flattened bone with a
ridge on the outer surface known as the spine; this ridge ends in a
freely-projecting process, the acromion, from which a branch often arises
known as the metacromion. This gives a bifurcate appearance to the end of
the ridge. The spine is less developed and the scapula is narrower in such
animals as the Dog and the Deer which simply run, and whose fore-limbs
therefore are not endowed with the complexity of movement seen, for
instance, in the Apes.

{37} [Illustration]

FIG. 27.--Right scapula of Dolphin (_Tursiops tursio_). × ¼. _a_, Acromion;
_af_, prescapular fossa; _c_, coracoid; _gc_, glenoid cavity; _pf_,
postscapular fossa. (From Flower's _Osteology_.)

[Illustration]

FIG. 28.--Side view of right half of shoulder girdle of a young Echidna
(_Echidna hystrix_). × 2/3. _a_, Acromion; _c_, coracoid; _cb_, coracoid
border; _cl_, clavicle; _css_, coraco-scapular suture; _ec_, epicoracoid;
gb, glenoid border; _gc_, glenoid cavity; _ic_, interclavicle; _pf_,
postscapular fossa; _ps_, presternum; _s_, spine; _ss_, suprascapular
epiphysis; _ssf_, subscapular fossa. (From Flower's _Osteology_.)

It has been pointed out that the area which lies in front of the spine, the
prescapular lamina, is most extensively developed in such animals as
perform complex movements with the fore-limbs. The Sea Lion and the Great
Anteater are cited by Professor G. B. Howes as examples of this
preponderance of the anterior portion of the scapula over that which lies
behind the spine. The general shape of the scapula varies considerably
among the different orders of mammals; but it always presents the
characters mentioned, which are nowhere seen among the Sauropsida except
among certain Anomodonts, which will be duly referred to (see p. 90). The
most conspicuous divergences from the normal are to be found in the Cetacea
and the Monotremata. In the former the acromion is approximated so nearly
to the anterior border of the blade-bone that the prescapular fossa is
reduced to a very small area; and in _Platanista_ the acromion actually
coincides with the anterior border, so that that fossa actually disappears.
In the Whales, too, the scapula is as a rule very broad, especially above;
it has frequently a fan-like contour. In the Monotremata the acromion also
coincides with the anterior border of the scapula; but the sameness of
appearance which it thus presents (in this feature) to the Cetacean scapula
is {38} apparently not due to real resemblance. What has happened in the
Monotremata is, that the prescapular fossa is so enormously expanded that
it occupies the whole of the inner side of the blade-bone, while the
subscapular fossa which, so to speak, should occupy that situation, has
been thus pushed round to the front, where it is divided from the
postscapular fossa by a slight ridge only.

The clavicle is a bone which varies much in mammals. It is sometimes
indeed, as in the Ungulata, entirely absent; in other forms it shows
varying degrees of retrocession in importance; it is only in climbing,
burrowing, digging, and flying mammals that it is really well developed.

[Illustration]

FIG. 29.--Shoulder girdle, with upper end of sternum (inner surface) of
Shrew (_Sorex_), after Parker, × 7. _a_, Acromion; _c_, coracoid; _cl_,
clavicle; _ec_, partially ossified "epicoracoid" of Parker, or rudiment of
the sternal extremity of the coracoid; ''ma'', metacromial process; _mss_,
ossified "mesoscapular segment"; _ost_, omosternum; _pc_, rudiment of
precoracoid (Parker); _ps_, presternum; _sr_^1, first sternal rib; _sr_^2,
second sternal rib. (From Flower's _Osteology_.)

In the higher Mammalia the coracoid[21] is present, but does not reach the
sternum as in the Monotremata. It is known to human anatomists as the
coracoid process of the scapula. It has been found, however, by Professor
Howes[22] and others, that this process really consists of two separate
centres of ossification, forming two separate bonelets, which in the adult
become firmly ankylosed to each other and to the scapula. These two
separate bones have been met with in the embryo of _Lepus, Sciurus_, and
the young of various other mammals belonging to very diverse orders, such
as Edentates and Primates. The separation even occasionally persists in the
adult. The question is, What is the relation of these bonelets to the
coracoid of the Monotremata and to the corresponding regions of reptiles?
Professor Howes terms the lower patch of bone the metacoracoid and the
upper the epicoracoid; {39} the former is alone concerned with the glenoid
cavity. It must therefore, one would suppose, correspond to the "coracoid"
of the Monotremata, while the upper piece of bone is the epicoracoid
process of that mammal. The Mammalia, therefore, higher as well as lower,
differ from the reptiles in that the coracoid is formed of two bones, the
exceptions being, among some other extinct forms, certain of the
Anomodontia, a group which it will be recollected is the nearest of all
reptiles to the mammals.

[Illustration]

FIG. 30.--Distal extremity of the humerus to show Epicondylar Foramina. A,
In _Hatteria_; B, in a Lizard (_Lacerta ocellata_); C, in the Domestic Cat;
D, in Man. _c.e_, External condyle; _c.i_, internal condyle. In A the two
foramina are developed (at _i_, the entepicondylar; at _ii_, the
ectepicondylar). The only canal (+) present in the Lizard (B) is on the
external ulnar side, in the cartilaginous distal extremity. In Man (D) an
entepicondylar process (_pr_) is sometimes developed and continued as a
fibrous band. (From Wiedersheim's _Anatomy of Man_.)

THE FORE-LIMB.--The humerus is of varying length among mammals. A feature
which it sometimes shares with the humerus of lower forms is the presence
of an entepicondylar foramen, a defect of ossification situated above the
inner condyle of that bone which transmits a nerve. The same foramen and an
additional ectepicondylar foramen are found in the ancient reptilian type
_Hatteria_ (_Sphenodon_); it occurs also in the Anomodont reptiles. It is
as a rule only the lower forms among mammals which show this foramen; thus
it is present in the Mole and absent in the {40} Horse. The fact that it is
occasionally met with in Man is an additional proof of the, in many
respects, ancient structure of the highest type of Primate.

The radius and the ulna, which together constitute the fore-arm, are both
present in a large number of mammals, but the ulna tends to vanish in the
purely walking and digitigrade Ungulates, being present, however, in the
more ancient forms of these Ungulates. In Man and in many other mammals the
radius can be moved from its normal position and crossed over the ulna;
this movement of pronation has been permanently fixed in the Elephant,
where the bones are crossed but cannot be altered in position by the
contractions of any muscles. Other types agree with the Elephant in this
fixation of the two bones.

[Illustration]

FIG. 31.--Bones of fore-arm and manus of Mole (_Talpa europaea_). × 2. _c_,
Cuneiform; _ce_, centrale; _l_, lunar; _m_, magnum; _p_, pisiform; _R_,
radius; _rs_, radial sesamoid (falciform); _s_, scaphoid; _td_, trapezoid;
_tm_, trapezium; _U_, ulna; _u_, unciform; _I-V_, the digits. (From
Flower's _Osteology_.)

The bones of the wrist show great variation among mammals. The greatest
number present are to be seen in such a type as the Mole. Here we have a
proximal row, consisting of the scaphoid, lunar, cuneiform, and pisiform,
which are arranged in their proper order, beginning with that on the radial
side of the limb, that side which bears the first digit. A second row
articulates proximally with these bonelets and distally with the
metacarpals; the bones composing it are, mentioning them in the same order,
trapezium, trapezoid, centrale, magnum, unciform.

The centrale does not, however, really belong to the distal carpal row, and
is as a rule situated in the middle of the carpus away from articulation
with the metacarpals. It is a bone which is not commonly present in the
mammalian hand, but is present in various lower forms, such as the Beaver
and Hyrax. It also occurs in such high types as the majority of Monkeys; it
is to be found in the Human foetal carpus. Many extinct forms possessed a
separate centrale. Its importance in the formation of the interlocking
condition of the Ungulate foot is referred to later, {41} on p. 196. The
only mammal which appears to have the proper five bones in the distal row
of the carpus corresponding to the five metacarpals is _Hyperoodon_, where
this state of affairs at least occasionally occurs. The final bone of that
series, the unciform, seems to represent two bones fused. Very often the
carpus is reduced by the fusion of certain of the carpal bones; thus among
the Carnivora it is usual for the scaphoid and the lunar to be fused. It is
interestingly significant that these bones retain their distinctness in the
ancestral Creodonts. In many Ungulates the trapezium vanishes. The
reduction of the toes in fact implies a reduction of the separate elements
of the carpus.

As to the digits of the mammalian hand, the greatest number is five, the
various supplementary bonelets known as prepollex and postminimus being, it
is now generally held, merely supplementary ossifications not representing
the rudiments of pre-existing fingers. They may, however, bear claws.[23]
The number of phalanges which follow upon the metacarpals is almost
constantly three in the mammals, excepting for the thumb, which has only
two. This is highly characteristic of the group as opposed to reptiles and
birds, and the increase in the number of these bones in the Whales and to a
very faint degree in the Sirenia is a special reduplication, which will be
mentioned when those animals are treated of.

THE PELVIC GIRDLE.--The pelvic girdle or hip girdle is the combined set of
bones which are attached on the one hand to the sacrum and on the other
articulate with the hind-limb. Four distinct elements are to be recognised
in each "os innominatum," the name given to the conjoined bones of each
half of the entire pelvis. These are:--the ilium, which articulates with
the sacrum; the ischium, which is posterior; the pubis, which is anterior;
and finally, a small element, the cotyloid, which lies within the
acetabular cavity where the femur articulates. The epipubes of the
Monotreme and the Marsupial are dealt with elsewhere (see p. 116) as they
are peculiar to those groups.

Professor Huxley pointed out many years since that while the Eutherian
Mammalia differ from the reptiles in the fact that the axis of the ilium
lies at a less angle with that of the sacrum, {42} _Ornithorhynchus_ comes
nearest to the reptile in the fact that this axis is nearly at right angles
to that of the sacrum. It is particularly interesting to find that this
peculiarity of _Ornithorhynchus_ is only acquired later in life, and that
the pelvis of the foetus conforms in these angles to the adults of other
mammalian groups. In any case, the backward rotation of the pelvis is a
mammalian characteristic, and it is most nearly approached among reptiles
by the extinct Anomodontia, whose affinities to mammals will be dealt with
on a later page (p. 90). Another peculiarity of the mammalian pelvis
appears to be the cotyloid bone already referred to. In the Rabbit this
bone completely shuts out the pubis from any share in the acetabular
cavity; later it ankyloses with that bone. In _Ornithorhynchus_ the
cotyloid or os acetabuli is a larger element of the girdle than is the
pubis. In other mammals, therefore, it seems to be a rudimentary structure.
But it seems to be a bone peculiar to and thus distinctive of the mammals
as compared with other vertebrates. The acetabular cavity is perforated in
_Echidna_ as in birds; but in certain Rodents the same region is very thin
and only closed by membrane, as in _Circolabes villosus_.

The number and the arrangement of the bones in the HIND-LIMB correspond
exactly to those of the fore-limb. The femur, which corresponds to the
humerus, shows some diversities of form. The neck, which follows upon the
almost globular head, the surface of articulation to the acetabular cavity
of the pelvis, has two roughened areas or tuberosities for the insertions
of muscles. A third such area, known as the third trochanter, is present or
absent as the case may be, and its presence or absence is of systematic
import. As a general rule the thigh-bones of the ancient types of mammals
are smoother and less roughened by the presence of these three trochanters
than in their modern representatives. The radius and the ulna are
represented in the hind-leg by the tibia and the fibula. These bones are
not crossed, and do not allow of rotation as is the case with the radius
and the ulna. In Ungulate animals there is the same tendency to the
shortening and rudimentary character of the fibula that occurs in the case
of the ulna, but it is more marked. It has been shown in tracing the
history of fossil Ungulates that the hind-limbs in their degree of
degeneration are as a rule ahead of the fore-limbs. This is natural when we
reflect that {43} the hind-limbs must have preceded the fore-limbs in their
thorough adaptation to the cursorial mode of progression. In the Mammalia
the ankle-joint is always what is termed cruro-tarsal, _i.e._ between the
ends of the limb-bones and the proximal row of tarsals; not in the middle
of the tarsus as in some Sauropsida (reptiles and birds). The bones of the
ankle are much like those of the hand; but there are never more than two
bones in the proximal row, which are the astragalus and the calcaneum. The
former is perhaps to be looked upon as the equivalent of the cuneiform and
lunar together. But the views as to the homologies of the tarsal bones
differ widely. Below these is the navicular, regarded as a centrale. The
distal row of the tarsus has four bones, three cuneiforms and a cuboid.
Reduction is effected by the soldering together of two cuneiforms as in the
Horse, by the fusion of the navicular and cuboid as in the Deer. No mammal
has more than five toes, and the number tends to become reduced in
cursorial animals (Rodents, Ungulates, Kangaroos).

[Illustration]

FIG. 32.--Anterior aspect of right femur of Rhinoceros (_Rhinoceros
indicus_). × ½. _h_, Head; _t_, great trochanter; _t_', third trochanter.
(From Flower's _Osteology_.)

TEETH.--The teeth of the Mammalia[24] differ from those of other
vertebrated animals in a number of important points. These, however,
entirely concern the form of the adult teeth, their position in the mouth,
and the succession of the series of teeth. Developmentally and
histologically there are no fundamental divergences from the teeth of
vertebrates lower in the scale.

In mammals, as for example in the Dog, the teeth consist of three kinds of
tissue--the enamel, the dentine, and the cement. The enamel is derived from
the epidermis of the mouth cavity, and the two remaining constituents from
the underlying dermis. The teeth originate quite independently of the jaws,
with which they are later so intimately connected; the independence of
origin being one of the facts upon which the current theory {44} of the
nature of teeth is founded. It has been pointed out that the scales of the
Elasmobranch fishes consist of a cap of enamel upon a base of dentine, the
former being derived from the epidermis and modelled upon a papilla of the
dermis whose cells secrete the dentine. The fact that similar structures
arise within the mouth (_i.e._ the teeth) is explicable when it is
remembered that the mouth itself is a late invagination from the outside of
the body, and that therefore the retention by its tissues of the capacity
to produce such structures is not remarkable.

[Illustration]

FIG. 33.--Diagrammatic sections of various forms of teeth. _I_, Incisor or
tusk of Elephant, with pulp cavity persistently open at base; _II_, Human
incisor during development, with root imperfectly formed, and pulp cavity
widely open at base; _III_, completely formed Human incisor, with pulp
cavity opening by a contracted aperture at base of root; _IV_, Human molar
with broad crown and two roots; _V_, molar of the Ox, with the enamel
covering the crown deeply folded, and the depressions filled up with
cement; the surface is worn by use, otherwise the enamel coating would be
continuous at the top of the ridges. In all the figures the enamel is
black, the pulp white; the dentine represented by horizontal lines, and the
cement by dots. (After Flower and Lydekker.)

The relations of the three constituents of the tooth in its simplest form
is shown in the accompanying diagram, where the intimate structure of the
enamel, dentine, and cement (or crusta petrosa as it is sometimes called)
is not indicated. The latter has the closest resemblance to bone. The
dentine is traversed by fine canals which run parallel to each other and
anastomose here and there. The enamel is formed of long prismatic fibres,
and is excessively hard in structure, containing less animal matter than
the other tooth tissues. To this fact is frequently {45} due the
complicated patterns upon the grinding teeth of Ungulates, which are
produced by the wearing away of the dentine and the cement, and the
resistance of the enamel.

The centre of the tooth papilla remains soft and forms the pulp of the
tooth, which is continuous with the underlying tissues of the gum by a fine
canal or a wide cavity as the case may be. In teeth which persistently grow
throughout the lifetime of the animal, as for example the incisors of the
Rodents, there is a wide intercommunication between the cavity of the tooth
and the tissues of the gum; only a narrow canal exists in, for instance,
the teeth of Man, and in fact in the vast majority of cases. The three
constituents of the typical teeth are not, however, found in all mammals;
the layer which is sometimes wanting is the enamel. This is the case with
most Edentates; but the interesting discovery has been made (by Tomes) that
in the Armadillo there is a downgrowth of the epidermis similar to that
which forms the enamel in other mammals, a rudimentary "enamel organ."

Teeth are present in nearly all the Mammalia; and where they are absent
there is frequently some evidence to show that the loss is a recent one.
The Whalebone Whales, the Monotremata, _Manis_, and the American Anteaters
among the Edentata are devoid of teeth in the adult state. In several of
these instances, however, more or less rudimentary teeth have been found,
which either never cut the gums or else become lost early in life. The
latter is the case with _Ornithorhynchus_, where there are teeth up to
maturity (see p. 113). Kükenthal has found germs of teeth in Whales, and
Röse in the Oriental _Manis_. The loss of the teeth in these cases seems to
have some relation to the nature of the food. In ant-eating mammals, as in
the Anteaters and _Echidna_, the ants are licked up by the long and viscid
tongue, and require no mastication. Yet it must be remembered that
_Orycteropus_ is also an anteater, like the Marsupial _Myrmecobius_, both
of which genera have teeth.

The first of the essential peculiarities of the mammalian teeth as compared
with those of other vertebrates concerns the position of the teeth in the
mouth. There is no undoubted mammal extinct or living in which the teeth
are attached to any bones other than the dentary, the maxilla, and the {46}
premaxilla. There are no vomerine, palatine, or pterygoid teeth, such as
are met with in Amphibia and Reptilia.

The other peculiarities of the mammalian teeth, though true of the great
majority of cases, are none of them absolutely universal.

But it is necessary to go into the subject at some length on account of the
great importance which has been laid upon the teeth in deciding questions
of relationship; moreover, largely no doubt on account of their hardness
and imperishability, our knowledge of certain extinct forms of Mammalia is
entirely based upon a few scattered teeth; while of some others, notably of
the Triassic and Jurassic genera, there is not a great deal of evidence
except that which is furnished by the teeth. Indeed the important place
which odontography holds in comparative anatomy is from many points of view
to be regretted, though inevitable. "In hardly any other system of organs
of vertebrated animals," remarks Dr. Leche, "is there so much danger of
confounding the results of convergence of development with true homologies,
for scarcely any other set of organs is less conservative and more
completely subservient to the lightest impulse from without." Affinities as
indicated by the teeth are sometimes in direct contradiction to those
afforded by other organs; or, as in the case of the simple Toothed Whales,
no evidence of any kind is forthcoming. Dr. Leche has pointed out that,
judged merely from its teeth, _Arctictis_ would be referred to the
Raccoons, though it is really a Viverrid; while _Bassariscus_, which Sir W.
Flower showed to be a Raccoon, is in its teeth a Viverrid. Mr. Bateson has
been obliged to hamper the subject with another difficulty.

In dealing with the variations of teeth,[25] Mr. Bateson has brought
together an immense number of facts, which tend to prove that the
variability of these structures is much greater than had been previously
recognised; that this variability is often symmetrical; and that in some
animals, as in "_Canis cancrivorus_, a South American fox, the majority
showed some abnormality." When we learn from Mr. Bateson that "of _Felis
fontanieri_, an aberrant leopard, two skulls only are known, both showing
dental abnormalities," it seems dangerous to rear too lofty a
superstructure upon a single fossil jaw. It must be noted too that, {47}
contrary to the prevailing superstition, it is not domestic animals which
show the greatest amount of tooth variation. As to special homologies
between tooth and tooth, with which we shall deal on a later page, Mr.
Bateson has urged almost insuperable difficulties.

[Illustration]

FIG. 34.--Skull of Dasyurus (lateral view). _al.sph_, Alisphenoid; _ang_,
angular process of mandible; _fr_, frontal; _ju_, jugal; _lcr_, lachrymal;
_max_, maxilla; _nas_, nasal; _oc.cond_, occipital condyle; _par_,
parietal; _par.oc_, paroccipital process; _p.max_, premaxilla; _s.oc_,
supraoccipital; _sq_, squamosal; _sq_', zygomatic process of squamosal.
(From Parker and Haswell's _Zoology_.)

[Illustration]

FIG. 35.--Upper and lower teeth of one side of the mouth of a Dolphin
(_Lagenorhynchus_), illustrating the homodont type of dentition in a
mammal. (After Flower and Lydekker.)

The teeth of the Mammalia are almost without exception "heterodont," _i.e._
they show differences of structure in different parts of the mouth. As a
general rule, teeth can be grouped into cutting incisors, sharp conical
canines, and molars, with a surface which is in the majority of cases
suited for grinding. In this they contrast with the majority of the lower
vertebrates, where the teeth are "homodont" (or, better, _homoeodont_),
_i.e._ all more or less similar and not fitted by change of form to perform
different duties. But there are exceptions on both sides. In {48} the
Toothed Whales the teeth are homodont, as they are in the frog and in most
reptiles; on the other hand, some of the remarkable reptiles belonging to
Professor Huxley's order of the Anomodontia have distinct canines, and show
other differentiations in their teeth.

A second characteristic of the mammalian dentition is the limited number of
the teeth, which rarely exceeds fifty-four. Here again the Toothed Whales
are an exception, the number of their teeth being as great as in many
reptiles. In the Mammalia the number of the teeth is fixed (excepting of
course for abnormalities), while in reptiles there is frequently no precise
normal. Two regions may be distinguished in every tooth--the crown and the
root; the latter, as its name denotes, is imbedded in the gum, while the
crown is the freely-projecting summit of the tooth. The varying proportions
of these two regions of the tooth enables us to divide teeth into two
series--the brachyodont and the hypselodont; in the latter the crown is
developed at the expense of the root, which is small; the hypselodont tooth
is one that grows from a persistent pulp or, at any rate, one that is long
open. Brachyodont teeth on the contrary have narrow canals running into the
dentine. The primitive form of the tooth seems undoubtedly to be a conical
single-rooted tooth, such as is now preserved in the Toothed Whales and in
the canine teeth of nearly all animals. The development of the teeth, that
is, the simple bell-shaped form of the enamel organ, seems to go some way
towards proving this; but it is quite another question whether we can
fairly regard the Whales as having retained this early form of tooth. In
their case the simplification, as is so often the case where organs are
simplified, seems to be rather degeneration than retention of primitive
characters. But this is a matter which must be deferred for the present.

The incisor teeth are generally of simple structure and nearly always
single rooted. In the Rodents, in the extinct Tillodontia and in
Diprotodont Marsupials, they have grown large, and, as has been already
stated, they increase in size continuously from the growing pulp. These
teeth have a layer of enamel only on the anterior face, which keeps a sharp
chisel-like edge upon them by reason of the fact that the harder enamel is
worn away more slowly than the comparatively soft dentine. The {49} "horn"
of the Narwhal is another modification of an incisor, as are the tusks of
Elephants. Among the Lemurs the incisors are denticulate, and serve to
clean the fur in a comb-like fashion. This is markedly the case in
_Galeopithecus_. The incisors are sometimes totally absent, as in the
Sloths, sometimes partially absent, as in many Artiodactyles, where the
lower incisors bite against a callous pad in the upper jaw, in which no
trace of incisors has been found.

Canine teeth are present in the majority of mammals, but are absent without
a single exception from the jaws of the Rodentia. The canine tooth of the
upper jaw is that tooth which comes immediately after the suture dividing
the premaxillary from the maxillary bone. The canines are as a rule simple
conical teeth, with but a single root; indeed they resemble what we may
presume to have been the first kind of tooth developed in mammals. In this
they resemble also as a general rule the foregoing incisors. But instances
are known where the canines are implanted by two roots. This is to be seen
in _Triconodon_, in the pig _Hyotherium_, in the Mole and some other
Insectivores, and in _Galeopithecus_, where the incisors also may be thus
implanted in the jaw. Furthermore, the simple condition of the crown of the
tooth may be departed from. This is the case with a Fruit Bat belonging to
the genus _Pteralopex_. In the more primitive Mammalia it is common to find
no great difference between the canines and incisors; such is the case with
the early Ungulate types of Eocene times, such as _Xiphodon_. In modern
mammals, however, especially among the Carnivora, the canines tend to
become larger and stronger than the incisors, and in some of the Cats and
in the Walrus these teeth are represented by enormous offensive tusks. It
is not rare for the canines of male animals to be larger than those of
their mates. There are also cases such as the Musk-deer and the Kanchil
where the male alone possesses these teeth, but only in the upper jaw. The
teeth which follow the canines are known as the grinders or cheek teeth, or
more technically as premolars and molars. These two latter terms separate
teeth which arise at different periods, and their use will be explained
later. In the meantime it may be pointed out that the cheek teeth are the
teeth which show the greatest amount of variation in their structure; this
is shown by the number and variety of the cusps in which {50} the biting
surface ends. The grinding teeth vary from simple one-cusped teeth,
precisely like canines, to teeth with an enormous number of separate
tubercles. In the former case it is hard to distinguish between incisors,
canines, and cheek teeth in the lower jaw, where no suture separates the
bone. Moreover it is quite common for the first cheek tooth in the lower
jaw to have the characters of a canine, while the true canine approximates
in its form to the antecedent incisors. This is so, for instance, with the
Lemurs, where the first premolar is caniniform, and the canine shares in
the curious procumbent attitude which distinguishes the lower incisors of
many of those animals.

A variable number of the anterior cheek teeth may be little more than
simple conical teeth; but the rest of the set are commonly more
complicated. No definite laws can be laid down as to the complication of
the posterior as compared with the anterior set. Broadly speaking, it is
purely herbivorous creatures in which the least difference can be detected
at the two extremities, and which are at the same time the most elaborately
decorated with tubercles and ridges. The converse is true that in purely
carnivorous animals, including insect- and fish-eating forms, there is the
greatest difference between the anterior set of grinding teeth and those
which follow. In these two respects such animals as a Lemur and a
Rhinoceros occupy the extremes. Furthermore, it may be said that omnivorous
creatures lie, as their diet would suggest, in an intermediate position.
Generally speaking, when there is a marked difference between the first
premolar and molars at the end of the series, there is a gradual
approximation in structure of a progressive kind. The tubercles become more
numerous in successive teeth; but the corollary which is apparently
deducible from this, _i.e._ that the last molar is the most elaborate of
the series, is by no means always true. The last cheek tooth indeed is
often degenerate. On the other hand, it is very markedly the largest of the
series in such diverse types as the Elephant, the hog _Phacochoerus_, and
the Rodent _Hydrochoerus_. It is a rule that the cheek teeth of the upper
jaw are more complicated than the corresponding teeth of the lower jaw.

The structure of the cheek teeth is very diverse among the Mammalia.
Broadly, two types are to be recognised. There are {51} teeth in which the
grinding surface is raised into a series of two, to many, tubercles sharper
or blunter as the case may be;--sharper and fewer at the same time in
carnivorous and especially in insectivorous types, more abundant in
omnivorous animals. To this form of tooth the term "bunodont" is applied.
There is no doubt that this is the earliest type of tooth; but whether the
fewer or the more cusped condition is the primitive one is a question that
is reserved for consideration at the end of the present chapter. The other
type of grinding tooth is known as "lophodont." This is exemplified by such
types as the Perissodactyla and Ungulates generally, and by the Rodents.
The tooth is traversed by ridges which have generally a transverse
direction to the long axis of the jaw in which the tooth lies. The ridges
may be regarded as having been developed between tubercles which they
connect and whose distinctness as tubercles is thereby destroyed. Lophodont
teeth are only found in vegetable-feeding animals.

[Illustration]

FIG. 36.--Molar teeth of _Aceratherium platycephalum_. × ½. _m.1-m.3_.,
Molars; _mh_, metaloph; _p.1-p.4_, premolars; _ph_, protoloph; _ps.f_,
parastyle fossa; _te_, tetartocone. (After Osborn.)

The special characteristics of the teeth of various groups of animals will
be considered further under the accounts of the several orders of recent
and fossil Mammalia.

[Illustration]

FIG. 37.--Two stages in the development of the teeth of a Mammal
(diagrammatic sections). _alv_, Bone of alveolus; _dent_, dentine;
_dent.s_, dental sac; _en_, enamel; _en.m_, enamel membrane; _en.m_^2,
enamel membrane of permanent tooth; _en.plp_, enamel pulp; _gr_, dental
groove; _lam_, dental lamina; _lam_', part of dental lamina which grows
downwards below the tooth germ; _n_, neck connecting germs of milk and
permanent tooth; _pap_, dental papilla; _pap_^2, dental papilla of
permanent tooth. (After O. Hertwig.)

A very general feature of the teeth of the Mammalia is what is usually
termed the diphyodont dentition. In the majority of cases there are two
sets of teeth developed, of which the first lasts for a comparatively short
time, and is termed on account of its usual time of appearance the "milk
dentition"; this is replaced later by the permanent dentition. In lower
vertebrates the teeth are replaced as worn away. There is not, however, so
great an antithesis in this matter between the Mammalia {52} and other
vertebrates as was at one time assumed. But in order to explain this very
important part of the subject it will be necessary to give some account of
the development of the teeth. The type selected is the Hedgehog, which has
been recently and carefully described by Dr. Leche of Stockholm, which type
has furthermore the advantage of being a "central" type of mammal. The
first step in the formation of the teeth is a continuous invagination of
the epithelium covering the jaw to form a deepish wall of tissue running in
the thickness of the jaw; this is perfectly continuous from end to end of
the lower jaw. From this "common enamel germ" (_Schmelzleiste_ of the
Germans[26]) "special enamel germs" (_Schmelzorgane_, enamel organs) are
developed here and there as thickenings in the form of buds {53} which
arise on the outer side of the fold of epithelium and some way above its
lower termination. These ultimately acquire a bell-like form, and are as it
were moulded on to a thickened concentration of the dermis beneath; they
then become separate from the downgrowth of the epithelium whence they have
arisen. Finally, each of the eight germs becomes one of the milk teeth of
the animal. The lower end of the sheet of invaginated epithelium, the
common enamel germ, is the seat of the formation of the second set of
teeth, of which, however, in the animal under consideration, there are only
two in each jaw. But corresponding to each of the enamel germs of the milk
dentition, with the exception of the first two molars, there is a slight
thickening of the end of the common enamel germ, which at a certain stage
is indistinguishable from the thickening which will become one of the
permanent teeth. We have thus the diphyodont arrangement. But this does not
exhaust the series of rudimentary teeth, though no more come to maturity
than those whose development has already been touched upon. In the upper
jaw a small outgrowth of the common enamel germ arises above and to the
outer side of the enamel germ of the third milk incisor; this does not
develop any further, but its resemblance to the commencing germ of a tooth
seems to indicate that it is the remnant of a tooth series antecedent to
the milk series. Furthermore, there are indications in the fourth premolar
of a fourth series of teeth posterior in appearance to the permanent
dentition. We arrive therefore at the important conclusion that although
here as elsewhere there are only two sets of calcified teeth ever
developed, there are feeble though unmistakable remains of two other
series, one antecedent to and the other posterior to the diphyodont
dentition. The gap therefore which separates the mammalian dentition from
that of reptiles is less than has hitherto appeared. Dr. Leche also
carefully studied the tooth development of _Iguana_; he found that in this
lizard there are four series of teeth which come to maturity, and a
rudimentary series antecedent to these which never produces fully formed
teeth.

In a few mammals there is a kind of dentition known as the monophyodont, in
which only one series of teeth reaches maturity; where in fact there is no
replacement of a milk series by a permanent dentition. Of the monophyodont
dentition Whales form an example. The Marsupials are very nearly an
instance of the {54} same phenomenon; for Sir W. Flower showed, and Mr.
Thomas confirmed his discovery, that only one tooth, according to Mr.
Thomas the fourth premolar, is replaced in that group. But even the purely
monophyodont dentition of the Toothed Whales is a more apparent than real
contrast to the diphyodont dentition elsewhere prevalent. An investigation
of the embryos of various Toothed Whales by Dr. Kükenthal and by Dr. Leche
has brought to light the highly important fact that two dentitions are
present, but that one only comes to maturity; from this fact obviously
follows the interesting question:--To which of the two dentitions of more
normal Mammalia does the monophyodont dentition of the Whales and
Marsupials belong? To this question a clear answer is fortunately possible.
As has been pointed out in the foregoing sketch of tooth development, and
has been illustrated in the figures, the milk teeth develop as lateral
outgrowths of the common enamel germ, while the permanent teeth arise from
the end of the same band of tissue. This fact enables it to be stated
apparently beyond a doubt that in the Whales and in the Marsupials it is
the milk dentition which is the only one to arrive at maturity. Thus the
earlier theoretical conclusion that the Marsupial dentition "is a secondary
dentition with only one tooth of the primary set left," is proved on
embryological grounds to be untrue. But there are other monophyodont
animals than those already mentioned.[27] _Orycteropus_, the Cape Anteater,
is an example. Mr. Thomas has lately discovered that in this Edentate there
is a set of minute though calcified milk teeth which probably never cut the
gum; here we have a different sort of monophyodontism, in which the teeth
belong to the second and not to the first set. Between the latter condition
and the diphyodont state are intermediate stages. Thus in the Sea Lions the
milk teeth are developed but disappear early, probably before the animal is
born.

In the typical diphyodont dentition, such as is exhibited for example in
Man and the vast majority of mammals, the milk teeth eventually completely
disappear and are entirely replaced by the permanent set of teeth, with the
exception, of course, of the molars, which though they are developed late
belong to the milk series. {55}

Their correspondence with the milk series is shown in an interesting way by
the close resemblance which the last milk premolar often bears to the first
molar. These two extremes of dentition, _i.e._ purely monophyodont and,
excepting for the molars, purely diphyodont, are however connected by an
intermediate state of affairs, which is represented by more than one stage.
In _Borhyaena_ (probably a Sparassodont) the incisors and the canines and
two out of the four premolars belong to the permanent dentition, while the
two remaining premolars and of course the three molars are of the milk
series. _Prothylacinus_, a genus belonging to the same group, has a
dentition which is a step or two further advanced in the direction of the
recent Marsupials. We find, according to Ameghino,[28] whose conclusions
are accepted by Mr. Lydekker, that the incisors, canines, and two premolars
belong to the milk series, while the permanent series is represented only
by the two remaining premolars. We can tabulate this series as follows:--

(1) Purely monophyodont, with teeth only of the first set--Toothed Whales.

(2) Incompletely monophyodont, as in the Marsupials, where there is a milk
dentition with only one tooth replaced.[29]

(3) Incompletely diphyodont, with the dentition made up partly of milk,
partly of permanent teeth, as in _Borhyaena_.

(4) Diphyodont, where all the teeth except the molars are of the second
set; this characterises nearly all the mammals.

As we pass from older forms to their more recent representatives there is
as a rule a progressive development of the form of the teeth. This is
especially marked among the Ungulata. The extremely complicated type of
tooth found in such a form as the existing Horse can be traced back through
a series of stages to a tooth in which the crown is marked by a few
separated tubercles or cusps. Arrived at this point, the differences
between the teeth of ancestral Horses and ancestral Rhinoceroses and Tapirs
are hard to distinguish with accuracy; and the same difficulty is
experienced in attempting to give a definition of other large orders by the
characters of the teeth, such as will apply to the Eocene or {56} even
earlier representatives of these families. Fig. 36 (p. 51) illustrating a
series of mammalian teeth will illustrate the above remarks. That there is
such a convergence in tooth structure shows that it is, theoretically at
least, possible to determine the ancestral form of the mammalian tooth.
Practically, however, the difficulties which beset such theorising are
great; that there are such divergent and such strongly-held antithetical
views is sufficient proof of this. Two main views hold the field: one,
which has found most favour in America, and is due chiefly to the labours
and persuasiveness of Professors Cope, Scott, Osborn, and others, is known
as "trituberculy."[30] The alternative view, as urged by Forsyth Major,
Woodward, and Goodrich, attempts to show that the dentition of the original
mammal included grinding teeth which were multicuspidate or
"multitubercular." There is much to be said for both views, and something
to be said against both.

[Illustration]

FIG. 38.--Molar teeth of A, _Phenacodus_, and B, the Creodont
_Palaeonictis_. _End_, endoconid; _hld_, hypoconulid; _hyd_, hypoconid;
_med_, metaconid; _prd_, protoconid. (After Osborn and Wortman.)

This question is, however, wrapped up in a wider one. Its solution depends
upon the ancestry of mammals. If the Mammalia are to be derived from
reptiles with simple conical teeth, then the first stage in the development
of trituberculy is proved. On the other hand, however, the evidence is
gradually growing that the Theromorpha represent more nearly than any
non-mammalian group with which we are acquainted the probable ancestral
form of the mammals. These animals offer some support to both the leading
views. _Cynognathus_ had triconodont teeth which, as will be pointed out
later, are a theoretically intermediate stage in the evolution of
tritubercular teeth; on the other hand, the teeth of _Diademodon_ and some
others are multituberculate, and have been very properly compared to the
multitubercular teeth of such primitive mammalia as the Ornithorhynchus.
Professor Osborn is no doubt correct in italicising a remark of an
anonymous writer in _Science_ to the effect that in _Diademodon_ the teeth,
though multitubercular, show the prevalence of three cusps arranged in the
tritubercular fashion. {57} But this may be only a proof that the
multitubercular antedates the tritubercular. It may be, indeed, that the
mammalian tooth was already differentiated among the mammal-like Saurians
and that from such a form as _Cynognathus_ the Eutheria and other forms in
which a tritubercular arrangement can be detected were evolved, and from
such form as _Tritylodon_ the Monotrematous branch of the mammals. This way
of looking at the matter harmonises a much-disputed question, but involves
a diphyletic origin of the mammals--an origin which for other reasons is
not without its supporters.

We shall now attempt to give a general idea of the facts and arguments
which support or tend to support "trituberculy." As a matter of fact the
name is inaccurate; for the holders of this view do not derive the
mammalian molar from a trituberculate condition, but in the first place
from a simple cone such as that of a crocodile!

To this main and at first only cusp came as a reinforcement an additional
cusp at each side, or rather at each end, having regard to their position
with reference to the long axis of the jaw. This stage is the "triconodont"
stage, and teeth exist among living as well as extinct mammals which show
this early form of tooth. We have, indeed, the genus _Triconodon_, so named
on that very account. Among living mammals the Seals and the Thylacine all
show some triconodont teeth. A Toothed Whale, it may be remarked, is a
living example of a mammal with monoconodont teeth. The three primary
cusps, as the supporters of Cope's theory of trituberculism denominate
them, are termed respectively the protocone, paracone, and metacone, or, if
they are in the teeth of the lower jaw, protoconid, paraconid, and
metaconid. At a slightly later stage, or coincidently, a rim partly
surrounded the crown of the tooth; the rim is known as the cingulum, and
from a prominent elevation of this rim a fourth cusp, the hypocone, was
developed. The three main cones then moved, or rather two of them moved, so
as to form a triangle; this is the tritubercular stage. Teeth of this
pattern are common, and occur in such ancient forms as Insectivora and
Lemurs, besides numerous extinct groups. An amendment has been suggested,
and that is to term the teeth with the simple primitive triangle
"trigonodont," and to reserve the term tritubercular for those teeth in
which the hypocone has appeared. The platform bearing the hypocone widened
into the {58} "talon"; and this ledge became produced into two additional
cusps, the hypoconule or hypoconulid, and the ectocone or ectoconid. Thus
the typical sextuberculate tooth of the primitive Ungulate, and indeed of
many primitive Eutherians, is arrived at. From this the still further
complicated teeth of modern Ungulates can be derived by further additions
or fusions, etc.[31] On the other hand, the development of the Primate
molar stops short at the stage of four cusps.

[Illustration]

FIG. 39.--Epitome of the evolution of a cusped tooth. 1, Reptile; 2,
_Dromatherium_; 3, _Microconodon_; 4, _Spalacotherium_; _me_, metaconid;
_pa_, paraconid; _pr_, protoconid; 5, _Amphitherium_. (After Osborn.)

That such a series can be traced is an undoubted fact. Every stage exists,
or has existed. But whether the stages can be connected or not is quite
another question. It is by three main lines of argument that the view here
sketched out in brief is supported. In the first place, the tracing of the
pedigrees of many groups of mammals has met with very considerable success;
and it is clear that as we pass from the living Horse and Rhinoceros, with
their complicated molars, to their forerunners, we find that both can be
referred to a primitive Ungulate molar with but six cusps. Going still
further back to the lowest Eocene and ancestral type as it appears,
_Euprotogonia_, we still find in the molar tooth the sextubercular plan of
structure. We can hardly get further back in the evolution of the
Perissodactyles with any probability of security. On the other hand, many
facts point to a fundamental relationship between the primitive Ungulates
and the early Creodonts. The latter frequently show plainly tritubercular
molars. Such Ungulates as _Euprotogonia_ and _Protogonodon_, though sex- or
quinque-tubercular as to their molars, have a distinctly prevailing
trituberculism, when the _size_ and importance of three of the cusps is
taken into account. But this {59} lacks finality as a convincing proof of
the tritubercular tooth as a primitive Ungulate tooth.

Professor Osborn has ingeniously utilised certain deviations from the
normal type of tooth structure (for the group) in favour of his
strongly-urged opinions. If the stages of development have been as he
suggests, a retrogression would naturally be in the inverse order; thus the
"apparently 'triconodont' lower molar of _Thylacinus_" may be interpreted
as a retrogression from a tritubercular tooth. In the same way may be
explained the triconodont teeth of Seals and of the Cetacean _Zeuglodon_.
Finally, the modern Toothed Whales have retrograded into "haplodonty."

Embryological evidence has also been called in, and with some success, to
contribute towards the proof of the tritubercular theory of teeth. Taeker
has shown that in the Horse and the Pig, and some other Ungulates, there is
first of all a single hillock or cusp, and that later the additional cones
arise separately. An apparent stumbling-block raised by these
investigations is that it is not always the protocone or its equivalent in
the upper jaw which arises first, as it obviously ought to do
phylogenetically. This, however, is not a final argument in either
direction. We know from plenty of examples that ontogenetic processes
sometimes do not correspond in their order with phylogenetic changes. Thus
in the mammalian heart the ventricle divides before the auricle; and of
coarse, phylogenetically, the reverse ought to occur, since a divided
auricle precedes a divided ventricle. This method of development has,
moreover, been interpreted otherwise. It has been held to signify that the
complex teeth of mammals are indeed derived from simple cones but by the
fusion of a number of those cones.

On the other hand there are the claims of the multitubercular theory of the
origin of mammalian teeth to be considered. The palaeontological evidence
has been already, to some extent, utilised. The occurrence of such teeth
among the possible forerunners of mammals, and in some of the most
primitive types of Mammalia, has been referred to. Señor Ameghino dwells
upon the sextubercular condition of many primitive mammals even belonging
to the Eutheria. In a recent communication[32] he attempts to identify six
tubercles in the molars of types belonging to a {60} variety of Orders. The
same condition, as has been noted, characterises that ancient Ungulate form
_Euprotogonia_. Even where the teeth seem at first sight to be
tritubercular a detailed study shows traces of otherwise vanished cusps.

It must be remembered in basing arguments upon the early Jurassic and
Cretaceous mammals, that our knowledge of them mainly depends upon lower
jaws, the teeth of which are usually simpler in pattern than those of the
upper jaws. Moreover, another fact, not always insisted upon, must not be
lost sight of. In many of those creatures the jaws were of small size, and
yet accommodated a large series of molar teeth. _Amphitherium_, for
example, had six molar teeth, and five is a number frequently met with. As
the teeth are so numerous and the jaws so small it seems reasonable to
connect the simplicity of the structure of the teeth with the need for
crowding a number together. The same argument may partly account for the
superabundant teeth of many Toothed Whales. It is true that the Manatee has
very numerous grinders which are yet complex; but then in this animal there
is a succession, and the jaw does not hold at a given time the entire
series, with which it is provided in relays. On the other hand, where there
are few molars they are often of the multitubercular type, or at least
approach it; of this the Multituberculate _Polymastodon_ is a good example;
so, too, the molars of _Hydrochoerus_, and of many other Rodents.

It is well known that the fourth deciduous molar of the upper jaw, which is
replaced by a permanent premolar in the fully adult animal, is of a more
complex structure than its successor. This may indeed be extended to
premolars earlier in the series. In the Dog "the second and first milk
molars closely resemble the third and second premolars"; now the milk
premolars belong evidently to the same dentition as the permanent molars,
and they are earlier teeth than the later-developed replacing teeth. It is
therefore significant that these earlier teeth should be more cuspidate
than the later teeth. It tells distinctly in favour of the simplification
as opposed to the complication of teeth in time, in the groups concerned.

These facts may possibly be applied in explanation of the simple teeth of
some of the Jurassic and Cretaceous mammals. It has been mentioned that
absolute trituberculy is exceedingly rare among those ancient creatures;
more generally there are to {61} be found at least traces of more cusps.
Now in some of them we may be dealing with instances of a complete tooth
change; the suppression, save for one tooth, which is found in Marsupials,
was probably not developed in at least some of these early mammals. The
simplicity may therefore have been preceded by complexity, and may have
been merely an adaptation to an insectivorous diet.

ALIMENTARY CANAL.--The _mouth_ of the Mammalia is remarkable for the fact
that with a few exceptions, such as the Whales, there are thick and fleshy
lips. The office of these is to seize the food. The roof of the mouth is
formed by the "hard palate" in front, which covers over the maxillary and
palatine regions. This region is often covered with raised ridges, which
have a symmetrical disposition, and are particularly strong in Ruminant
animals. They are much reduced in the Rodents, where the anterior part of
the palate is ill-defined owing to the way in which its sides fade into the
lateral surface of the face. It has been shown that these ridges, in the
Cat at least, develop as separate papilliform outgrowths, and it has been
suggested that these papillae, which later become united to form the
ridges, are the last remnant of palatine teeth such as occur in lower
vertebrates.

[Illustration]

FIG. 40.--Palatal folds of the Raccoon (_Procyon lotor_). _p.p_, Papilla
palatina; _r.p_, palatal folds. (From Wiedersheim's _Structure of Man_.)

The _tongue_ is a well-developed organ, usually playing a double part. It
acts as an organ of prehension, especially in such animals as the Giraffe
and the Anteater, where it is long and protrusible beyond the mouth for a
considerable distance. It also carries gustatory organs, which serve for
the discrimination of the nature of the food. Beneath the tongue there may
be a hardish plate, known as the sublingua. This is especially prominent in
the Lemurs, where it projects as a horny structure below the tongue, and
has an independent and free tip. It is supported in some of these animals
by a cartilaginous {62} structure. It is held by Gegenbaur that this organ
is the equivalent of the reptilian tongue, and that in the skeletal
vestiges which it contains are to be found the equivalents of the hyoid
skeletal cartilages which support the tongue in lizards. In this case the
tongue of mammals is a subsequently added structure.

The _oesophagus_ leads from the mouth cavity to the _stomach_. The latter
organ has commonly a distinctive shape in mammals. This is well shown in
Man. The orifices of the oesophagus and intestine are somewhat
approximated; and this causes a bulging of the lower border of the organ,
usually spoken of as the greater curvature. A stomach of this typical form
is found in many orders of mammals, and is unlike the stomach in any of the
groups of lower vertebrates in shape. Sometimes the shape of the organ is
greatly altered: it may be drawn out, sacculated, or divided, as in the
Ruminants and Whales, into a series of differentiated chambers, each of
which plays some special part in the phenomena of digestion.

The _intestine_ of mammals is always long and much coiled, though the
length and consequent degree of coiling naturally varies. On the whole it
is perhaps safe to say that it is shorter in carnivorous than in
vegetable-feeding beasts. Thus the Paca has an intestine of 39 inches total
length, while the Cat, an animal of about the same size, has an intestine
which is only 36 inches long. A fish diet, however, to judge from the
Seals, is associated with a long intestinal tract. The intestine is
divisible in the vast majority of mammals into a small and a large
intestine. The two are separated by a valvular constriction save in certain
Carnivores; and in the majority of cases the distinction is also emphasised
by the presence at the junction of a blindly-ending diverticulum, the
_caecum_. This latter organ varies greatly in length, being very short in
the Cat-tribe and exceedingly long in Rodents. Its size is, to some extent,
dependent upon the flesh-eating or grass-eating propensities of the animal
in which it occurs. One of the longest caeca is possessed by the Vulpine
Phalanger, in which the organ is one-fifth of the length of the small
intestine; while the opposite extremity is reached by _Felis macroscelis_,
which has a small intestine one hundred times the length of the caecum.

{63} [Illustration]

FIG. 41.--Different forms of the stomach in Mammals. A, Dog; B, _Mus
decumanus_; C, _Mus musculus_; D, Weasel; E, scheme of the Ruminant
stomach, the arrow with the dotted line showing the course taken by the
food; F, Human stomach. _a_, Minor curvature; _b_, major curvature; _c_,
cardiac end. G, Camel; H, _Echidna aculeata_. _Cma_, Major curvature;
_Cmi_, minor curvature. I, _Bradypus tridactylus_. _Du_, Duodenum; _MB_,
coecal diverticulum; **, outgrowths of duodenum; +, reticulum; ++, rumen.
_A_ (in E and G), Abomasum; _Ca_, cardiac division; _O_, psalterium; _Oe_,
oesophagus; _P_, pylorus; _R_ (to the right in E and to the left in G),
rumen; _R_ (to the left in E and to the right in G), reticulum; _Sc_,
cardiac division; _Sp_, pyloric division; _WZ_, water-cells. (From
Wiedersheim's _Comparative Anatomy_.)

An interesting point in connexion with the gut of mammals is the varying
proportion of the small to the large intestine. As a general rule the
former is very considerably longer than the latter; in _Paradoxurus_, for
instance, the small intestine may be fifteen times the length of the large.
The excess of length of one section over the other is not generally so
marked {64} as this. In _Phalanger maculatus_ the two sections of the gut
are as nearly as possible equal in length, while in _Phaseolarctos_ the
large intestine is considerably longer than the small, the lengths being
respectively 160 inches and 111 inches. It is common among the Marsupials
and also among the Rodents for these proportions to exist, _i.e._ for the
large intestine to be as long as, or longer than, the small. But there are
so many exceptions that no general statements can be extracted from the
facts.

Some few details will be found in the systematic part of this book. Mr.
Chalmers Mitchell has brought forward some reasons for associating a great
length of large intestine with an archaic systematic position, in the birds
at any rate. The facts here briefly touched upon are not at variance with
the extension of such a view to the mammals.

[Illustration]

FIG. 42.--Diagrammatic plan of the liver of a Mammal (posterior surface).
_c_, Caudate lobe; _cf_, cystic fissure; _dv_, ductus venosus; _g_,
gall-bladder; _lc_, left central lobe; _ll_, left lateral lobe; _llf_, left
lateral fissure; _p_, portal vein entering transverse fissure; _rc_, right
central lobe; _rl_, right lateral lobe; _rlf_, right lateral fissure; _s_,
Spigelian lobe; _u_, umbilical vein; _vc_, post-caval vein. (After Flower
and Lydekker.)

Appended to the alimentary tract are three glands or sets of glands.
Opening into the mouth cavity are the _salivary glands_, which are of
enormous size in Anteaters, and small or absent in Whales. In their number
and position these glands are characteristic of mammals. Into the intestine
open the ducts of the pancreas and liver, two glands which the mammals
share with lower vertebrates. The form of the _liver_ is, however,
generally characteristic of mammals. It is divided as a rule into a right
and a left half, the line of division being marked by the insertion of the
umbilical ligament, a vestige of the primitive ventral mesentery. Each half
is again commonly subdivided into central and lateral lobes. In addition to
these, two other divisions are often to be seen--the Spigelian and the
caudate lobe. The liver is less divided in Cetacea and {65} some others,
very much subdivided in Rodents and other groups. The degree of subdivision
and the proportions of the several lobes frequently offer valuable
systematic characters. The gall-bladder may be present or absent; it is
always a diverticulum of the hepatic duct. The two are never separate, as
in birds, for instance.

ORGANS OF CIRCULATION.--The heart of all mammals is a completely
four-chambered organ. In the adult heart there is no communication between
the right and left halves. The auricles are comparatively thin-walled, the
ventricles thick-walled, in relation to the amount of work that they have
severally to perform. The right ventricle, moreover, which has only to
drive the blood into the lungs, is much thinner-walled than the left
ventricle, which is concerned with the entire systemic circulation. The
exits of the arteries and the auriculo-ventricular orifices are guarded by
valves, which are so arranged as only to permit the blood to flow in the
proper direction. But these valves have a morphological as well as a
physiological interest. At the origin of each artery, the aorta and the
pulmonary, there is a row of three watch-pocket valves, as they have been
generally termed on account of their form. These three valves meet
accurately in the middle of the lumen of the arterial tube when liquid is
poured into them from above, and thus completely occlude the orifice. The
auriculo-ventricular valves differ in structure in the two ventricles. That
of the left ventricle has only two flaps, and is therefore often spoken of
as the bicuspid or mitral valve. Both these flaps are membranous, and
together they completely surround the exit from the auricle into the
ventricle. The edges of the valve are bound down to the parietes of the
heart by numerous branching tendinous threads, the chordae tendineae, which
often take their origin from pillar-like muscles arising from the walls of
the heart, the so-called musculi papillares. The valve of the right
ventricle is composed of three flaps, and is therefore often spoken of as
the tricuspid valve; it is in the same way membranous, and has chordae
tendineae and musculi papillares connected with it. The disposition of the
musculi papillares and their number differ in different mammals, but no
exhaustive study has as yet been made of the arrangements in different
groups; the amount of individual variation even is not known, though it is
certainly considerable in some cases, for {66} instance in the heart of the
Rabbit. The heart of the Monotremata presents differences of some
importance from those of other Mammalia; the modern knowledge of the
Monotrematous heart is mainly due to Gegenbaur[33] and Lankester,[34] in
whose memoirs references to the older literature will be found. The
principal features of interest in which the heart of the Monotremata
differs from that of the higher Mammalia are these. When the two ventricles
are cut across transversely, the cavity of the right is seen to be wrapped
round that of the left in a fashion precisely like that of the bird's
heart; on the other hand in the higher mammal the two cavities lie side by
side. The main difference between Monotremes and other Mammals concerns the
right auriculo-ventricular valve. The differences which it presents from
the corresponding structure of the rest of the Mammalia are two: in the
first place, the valve itself does not completely surround the ostium; it
is only developed on one side; the septal half (_i.e._ that turned towards
the interventricular septum) is either entirely absent or more generally
represented by a small bit of membrane; nevertheless I found[35] recently
in an _Ornithorhynchus_ heart a complete septal half to the right
auriculo-ventricular valve. The second point of interest in connexion with
this valve is, that the musculi papillares instead of ending in chordae
tendineae attached to the free edge of the valve are directly attached to
the valve, and in some cases pass through its membranous flap, to be
attached to its origin at the boundary of the auricle and of the ventricle.
The invading of the valve-flap by muscle in this way is highly interesting,
as it recalls the heart of the bird and of the crocodile. The imperfect
condition of the valve (from which, as has already been stated, the septal
half is as a rule nearly absent) is a point of resemblance to the heart of
the bird; the corresponding valve of the crocodile's heart being complete.

{67}

[Illustration]

FIG. 43.--_Lepus cuniculus._ Ventral view of the vascular system. The heart
is somewhat displaced towards the left of the subject; the arteries of the
right and the veins of the left side are in great measure removed. _a.epg_,
internal mammary artery; _a.f_, anterior facial vein; _a.m_, anterior
mesenteric artery; _a.ph_, anterior phrenic vein; _az.v_, azygos vein;
_br_, brachial artery; _c.il.a_, common iliac artery; _c.il.v_, common
iliac vein; _coe_, coeliac artery; _d.ao_, dorsal aorta: _e.c_, external
carotid artery; _e.il.a_, external iliac artery; _e.il.v_, external iliac
vein; _e.ju_, external jugular vein; _fm.a_, femoral artery; _fm.v_,
femoral vein; _h.v_, hepatic veins; _i.c_, internal carotid artery; _i.cs_,
intercostal vessels; _i.il.a_, internal iliac artery; _i.il.v_, internal
iliac vein; _i.ju_, internal jugular vein; _i.l_, iliolumbar artery and
vein; _in_, innominate artery; _l.au_, left auricle; _l.c.c_; left common
carotid artery; _l.pr.c_, left pre-caval vein; _l.v_, left ventricle;
_m.sc_, median sacral artery; _p.a_, pulmonary artery; _p.epg_, epigastric
artery and vein; _p.f_, posterior facial vein; _p.m_, posterior mesenteric
artery; _p.ph_, posterior phrenic veins; _pt.c_, post-caval vein; _p.v_,
pulmonary vein; _r_, renal artery and vein; _r.au_, right auricle; _r.c.c_,
right common carotid artery; _r.prc_, right pre-caval vein; _r.v_, right
ventricle; _s.cl.a_, right subclavian artery; _s.cl.v_, subclavian vein;
_spm_, spermatic artery; _s.vs_, vesical artery; _ut_, uterine artery and
vein; _vr_, vertebral artery. (From Parker's _Zootomy_.)

There are also features in the system of arteries and veins which are
eminently distinctive of mammals. In the first place, the aorta leaving the
heart and conveying blood to the body is only a half arch, and bends to the
left side as seen in Fig. 43. The right and left halves are present in
reptiles, and meet behind the heart. In the bird the right half alone has
remained. This fact, therefore, shows that the mammal cannot have been
derived from a bird-like ancestor, but that both must have independently
come from an ancestor with both halves of the aortic arch present, of which
one half has disappeared in one group, and the other half in the other. It
is an interesting fact, too, to notice that the four {68} cavities of the
mammal's heart, which fourfold division it shares with birds alone, do not
exactly correspond compartment for compartment with those of the bird's
heart, at least in so far as concerns the ventricles. For the reptilian
heart is provided with only one ventricle, and therefore the division of
that cavity must have been independently accomplished in mammals and in
birds.

There are two features in the venous system which distinguish all the
Mammalia (with the exception of _Echidna_ in one of these points) from
vertebrates standing lower in the series. The hepatic portal system is
limited to a vein which conveys to the liver blood derived from the
alimentary tract; in no mammal except in _Echidna_ is there any
representative of the anterior abdominal vein of lower vertebrates. In that
animal there is such a vein, which apparently arises from a capillary
network upon the bladder and passes up, supported by a membrane, along the
ventral wall of the abdomen to the liver, thus emptying blood into that
organ exactly as does the anterior abdominal vein of the frog. In no mammal
is there any trace of a renal portal system. The kidneys derive their blood
from the renal arteries only.

Many mammals have two superior venae cavae; this is the case, for instance,
in the Elephant and the Rodents and other types lying comparatively far
down in the series. In most if not in all mammals there are considerable
remains of one of the posterior cardinals, in the form of the azygos vein,
which opens into the vena cava superior or pre-caval vein, _i.e._ the
superior cardinal just before the latter debouches into the heart. This one
posterior cardinal is usually on the right side; but it may be on the left
side, for instance in _Trichosurus vulpecula_. In _Halmaturus bennettii_
there are two azygos veins, one left and one right, of which the left is
rather the larger.[36]

URINARY ORGANS.--The kidneys in the Mammalia have a compact form, which
contrasts with the somewhat diffuse and vaguely-outlined kidneys of the
Sauropsida. In mammals the organ is as a rule of that peculiar shape which
is called "kidney-shaped"; a depression termed the hilum, which receives
the ducts of the glands, indenting the border of an otherwise oval-shaped
gland. In some few mammals the kidney is broken up {69} into lobules; this
is the case with the Whales, the Bears, the Oxen, and a few other forms. A
curious fact about the kidneys of the Mammalia is their very general
asymmetry of position. One of them usually lies in a more advanced position
than the other. The ureters lead from the kidneys to the urinary bladder,
which in its form and relations is quite distinctive of the Mammalia. The
bladder is formed out of the remains of the allantois, and is therefore not
the exact homologue of the bladder of the frog, which is the equivalent of
the entire sac which grows out of the cloaca in the mammal, and is the
foetal allantois. The ureters open into the bladder in the higher Mammalia,
but lower down in the urino-genital passage in the more primitive mammals.

THE BODY CAVITY.--The Mammalia differ from all other living vertebrates by
the arrangement of the body cavity in which lie the viscera. That cavity is
divided into two by a partly muscular and partly tendinous partition, the
diaphragm. No other vertebrate has this precise disposition of the coelom.
The diaphragm lies usually transversely to the longitudinal axis of the
body, but gets a much more oblique arrangement in the Cetacea and the
Sirenia, whose needs demand a more expanded chamber for the lungs. For in
front of the diaphragm lie the lungs and heart; behind it the stomach,
liver, intestines, and the organs of reproduction and excretion. The
diaphragm is used in respiration; when its muscles contract, the surface
directed toward the pleural cavity becomes less convex, and the cavity of
the lungs is thus increased, allowing them to expand under the pressure of
the entering air.

THE LUNGS.--The lungs of the Mammalia differ from those of animals lying
lower in the series by the fact, just referred to, that they occupy a
pleural cavity completely shut off from the abdomen by the diaphragm. As a
rule the lungs of the Mammalia are to be distinguished by their more or
less extensive lobation. In the Whales, however, and in the Sirenia, they
are not much divided, but present the appearance of the simple sac-like
lungs of the reptiles. In some mammals there is a median and posterior
unpaired lobe of the lung, which lies in the post-pericardial cavity behind
the pericardium. This is not universally present. The lungs are very
frequently not symmetrical in their lobation, the number of separate lobes
on the right side {70} and on the left being different. The lungs of
mammals agree with those of the lower reptiles in being freely suspended
within their coelomic cavity, and in not being, as in birds, crocodiles,
and the Varanidae among lizards, tied down to the dorsal surface of that
cavity by a sheet of peritoneum covering them.

[Illustration]

FIG. 44.--Part of a sagittal section of an ovary of a child just born.
_bl.v_, Blood-vessels; _foll_, strings and groups of cells derived from the
germinal epithelium becoming developed into follicles; _g.ep_, germinal
epithelium; _in_, ingrowing cord of cells from the germinal epithelium;
_pr.ov_, primitive ova. (From Hertwig, after Waldeyer.)

THE GONADS (OVARIES AND TESTES).--The ovary in the Mammalia is always
paired; there is never a partial or complete abortion of one gonad as in
birds--except of course in pathological cases. The ovaries are small, and
lie in the abdominal cavity behind the kidneys. In the immense majority of
the Mammalia the ova which are produced within the ovaries are of minute
size; those of even the colossal Rorqual are, so far as we know, not
markedly larger than the ova of a Mouse. The smallness of size of these
reproductive elements implies necessarily an absence of much nutritive
yolk; and as a consequence the developing embryo, since it is not hatched
in an early stage as a free living larva, has to be nourished by the
mother, to whose tissues it is attached through the intermediary of the
placenta, a structure partly composed of foetal structures derived from the
embryo, and partly of portions of the lining membranes of the uterus of the
mother. The ova of the {71} Eutherian mammals, including the Marsupials,
are very small as compared with those of any other vertebrates, excepting
only _Amphioxus_, where the young are hatched early as free swimming
larvae. They also differ in a highly characteristic way in the mode of
their development within the ovary. These processes are to some extent
illustrated in Fig. 44. The main framework of the ovary is formed of the
so-called "stroma," which is a mass of tissue formed of more or less
connective-tissue-like cells. Within this are numerous cavities, the
Graafian follicles. The very young follicles consist of but a single layer
of follicular cells surrounding the ovum, which lies centrally. The
follicular cells gradually increase in number until the ovum lies in the
midst of several layers of cells. At this period a vacuity is formed
between some of these cells, and grows into a large cell-free cavity; the
ovum does not lie loosely in this space, but is connected at one side with
the follicular cells, which still line the interior of the Graafian
follicle by the so-called discus or cumulus proligerus. The egg or ovum
has, moreover, a layer of cells immediately surrounding itself. All these
facts can be gathered by an inspection of Fig. 45. It has been shown that,
as in lower vertebrates, the cells immediately surrounding the ovum are
connected with it directly by delicate processes which penetrate the actual
membrane of the egg.

[Illustration]

FIG. 45.--Two stages in the development of the Graafian follicle. A, With
the follicular fluid beginning to appear; B, after the space has largely
increased. _caps_, Capsule; _disc_, cumulus proligerus; _memb_, membrana
granulosa; _ov_, ovum; _sp_, space containing fluid. (After Hertwig.)

[Illustration]

FIG. 46.--Ovarian egg of _Echidna_. _b_, Basilar membrane; _fe_, follicular
epithelium; _o_, oil globules; _vm_, vitelline membrane; _y_^1, _y_^2,
yolk. (Partly after Caldwell.)

The only ova which depart at all in structure from that above described are
those of the Monotremata. The credit of this {72} discovery rests with Owen
and with Professor Poulton, who pointed out in 1884,[37] that the ovum of
_Ornithorhynchus_ is very large as compared with those of other Mammalia (6
mm. as against .2 mm.), that it is filled with yolk, and that it completely
fills the follicle, being surrounded by two layers of follicular cells
only. This latter fact was proved by Caldwell. Subsequently Gyldberg[38]
and I[39] described the ovarian ovum of _Echidna_, showing it to be
identical with that of _Ornithorhynchus_. Later still a more elaborate and
beautifully illustrated paper was published by Caldwell[40] upon the early
stages of development in the Monotremata and Marsupials, in which the ovum
of the former was accurately described (see Fig. 46). In the particulars
mentioned above, the ovum of the Monotremata is practically identical with
that of the large-yolked ova of the Sauropsida. {73}

[Illustration]

FIG. 47.--_Lepus cuniculus._ The anterior end of the vagina, with the right
uterus, Fallopian tube, and ovary. (Nat. size.) Part of the ventral wall of
the vagina is removed, and the proximal end of the left uterus is shown in
longitudinal section, _fl.t_, Fallopian tube; _fl.t_', its peritoneal
aperture; _l.ut_, left uterus; _l.ut_', left os uteri; _ov_, ovary; _r.ut_,
right uterus; _r.ut_', right os uteri; _s_, vaginal septum; _va_, vagina.
(From Parker's _Zootomy_.)

It is the general rule among vertebrate animals that the ovaries are
completely independent of the ducts which convey their products to the
exterior. In certain fishes, however, there is an absolute continuity
between the two structures, which is believed to be due to a simple
concrescence between the originally distinct ovary and oviduct. The latter
has grown round the former, an obvious advantage in preventing the eggs
from wandering into the abdominal cavity and becoming lost. In the Mammalia
we find discontinuity as a general rule. But in quite a number of forms
folds of the lining membrane of the abdominal cavity are developed, which
practically ensure the passage of the ova into the oviduct when they are
extruded from the ovaries. The oviduct, moreover, has a large and
fimbriated mouth, called in human anatomy--which is provided with a number
of fanciful names--the morsus diaboli. This almost wraps round the ovary,
and thus prevents the ova from straying in the wrong direction. Moreover,
the ovary itself is often so arranged that it can easily be withdrawn into
a pocket of the peritoneum, from which the obvious exit is by the gaping
mouth of the oviduct. This disposition of the generative parts is still
further modified in a few animals, such as the Rat[41] and the
Kinkajou.[42] In these animals the mouth of the oviduct actually opens into
the interior of a closed chamber which contains the ovary. In this case
there is but one route for the {74} extruded ova to follow. This series of
steps in the perfecting of the mode of safe extrusion of the ova is highly
interesting, and is a piece of evidence in favour of the high position of
the mammals.

[Illustration]

FIG. 48.--Female urino-genital apparatus of various Marsupials. A,
_Didelphys dorsigera_ (young); B, _Trichosurus_; C, _Phascolomys wombat_.
_B_, Urinary bladder; _Cl_, "cloaca"; _Fim_, fimbriae; _g_, clitoris; _N_,
kidney; _Od_, Fallopian tube; _Ot_, aperture of Fallopian tube; _Ov_,
ovary; _r_, rectum; _Sp_, septum dividing vagina; _Sug_, urino-genital
sinus; _Ur_, ureter; _Ut_, uterus; _Ut_', opening of the uterus into the
median vagina (_VgB_); _Vg_, lateral vagina; _Vg_', its opening into the
urino-genital sinus; + (in B), point of approximation of uteri; + (in C)
and *, rectal glands. (From Wiedersheim's _Comparative Anatomy_.)

{75}

The oviducal apparatus of the mammal is more specialised than that of lower
vertebrates. It is most simple, as might be imagined, in the egg-laying
Monotremes, where, indeed, it is on the same level as that of reptiles. But
in the Eutheria the fimbriated mouth of the oviduct passes into a narrow
and winding tube, the Fallopian tube; this widens into a uterus, and the
two uteri combine into a single tube in the higher forms. They are called
the Monodelphia on this account. In the Marsupials the uteri are distinct
though they often join above, and from this junction depends a median
"uterus." After the uterus or the uteri follows in every case a single
vagina.

The testes of the Mammalia, like those of other vertebrates, occupy
primitively a position within the body cavity precisely corresponding to
that of the ovaries. And in the lowly-organised Monotremata, and some other
forms, such as the Whales, they retain that primitive position within the
body. It is, however, distinctive of the Mammalia as opposed to lower
vertebrates that the testes descend later into a scrotum, which is simply a
protrusion of the skin of the body surrounded by muscles, and, of course,
containing a section of the body cavity in which lie the testes. The penis
of the Mammalia, represented by the clitoris and associated structures in
the female, is of a structure entirely peculiar to this group.

[Illustration]

FIG. 49.--Brain of Dog. A, ventral; B, dorsal; C, lateral aspect. _B.ol_,
Olfactory lobe; _Cr.ce_, crura cerebri; _Fi.p_, great longitudinal fissure;
_HH_, _HH_^1, lateral lobes of cerebellum; _Hyp_, hypophysis; _Med_, spinal
cord; _NH_, medulla oblongata; _Po_, pons Varolii; _VH_, cerebral
hemispheres; _Wu_, middle lobe (vermis) of cerebellum; _I-XII_, cerebral
nerves. (From Wiedersheim's _Comparative Anatomy_.)

THE BRAIN.--Inasmuch as Professor Wiedersheim has said with perfect truth
that "the brain of the extinct Ungulate _Dinoceras_ shows so striking a
likeness to that of a lizard that one would be compelled to explain it as
that of a lizard without a knowledge of the skeleton," it is clear that to
define the mammalian brain is a difficult matter. The existing Mammalia,
however, all possess brains which can be readily distinguished from those
of vertebrates lying lower in the scale. They are of relatively large size,
brought about mainly by the dimensions of the cerebral hemispheres, which
have an importance in this class of vertebrates that they have not
elsewhere. Coupled with this large size of the hemispheres is a more
elaborate system of transverse commissures uniting the two; and this
culminates in the higher Mammalia, where the corpus callosum attains a
large size and great physiological importance. A {76} very marked feature,
moreover, of the mammal's brain is the development of regular fissures upon
its surface, which fissures are only absent from _Ornithorhynchus_, various
small Rodents, Bats, and Insectivores, among living mammals. It is
sometimes, but erroneously, said that the more complicated the fissures of
the brain are, the higher in intelligence and "zoological position" is the
possessor of that brain. Instances can undoubtedly be quoted to support
such a view; but they are {77} merely selected cases, which do not indicate
a wide applicability of such a generalisation. Thus it is true that the
brain of a Man is more elaborate in its furrows and convolutions than is
that of a Cat. The real fact of the matter is, that the complexity of the
brain from this point of view increases with the size of the animal within
the group.

[Illustration]

FIG. 50.--_Lepus cuniculus._ Longitudinal vertical section of the brain.
(Nat. size.) _a.co_, Anterior commissure; _b.fo_, body of the fornix; _cb_,
cerebellum, showing arbor vitae; _c.c_, crus cerebri; _c.h_^1,
parencephalon or cerebral hemisphere; _c.h_^2, temporal lobe; _c.ma_,
corpus mammillare; _cp.cl_, corpus callosum; _f.m_, foramen of Monro;
_inf_, infundibulum; _l.t_, lamina terminalis; _ly_, lyra; _m.co_, middle
commissure; _m.o_, medulla oblongata; _o.ch_, optic chiasma; _o.l_^1,
_o.l_^2, corpora quadrigemina or optic lobes; _olf_, olfactory lobe;
_p.co_, posterior commissure; _pd.pn_, peduncle of the pineal "gland,"
_pn_; _p.fo_, anterior pillar of the fornix; _pty_, pituitary body; _pv.a_,
pons Varolii; _sp.lu_, septum lucidum; _v_^4, fourth ventricle; _vl.ip_,
velum interpositum; _v.vn_, valve of Vicussens; _II_, optic nerve. (From
Parker's _Zootomy_.)

The Gorilla and the Chimpanzee have a more furrowed brain than has the
little Marmoset; the Bear a more complicated brain than the Weasel, etc.
The most highly-convoluted brains of all mammals are those of the
Elephants, and there does not seem in the Ungulates to be so marked a
relation between size and abundance of fissures as there is among other
mammals. A regular plan of the fissures can be detected with certainty for
each group considered by itself; but it is not so easy to homologise the
details of arrangement from group to group. This is so far in accord with
the view that the existing groups of mammals have diverged from each other
_ab initio_.

Another marked characteristic of the mammalian as opposed to other brains
is the relatively small importance in size and yet the fourfold nature of
the optic lobes. What was the case with the optic lobes of the early
Ungulates is difficult to understand, on account of the fact that the casts
are necessarily imperfect. {78} Altogether the enormous progress in the
complexity of the brain from the early Tertiary mammals down to the
present, is one of the most remarkable revelations of palaeontology. It
goes perhaps some way in explaining the remarkable diversity in mode of
life exhibited by the mammals as compared, for example, with the birds,
whose brains have not diverged so much or in so many directions from the
primitive form.

THE PRESENT DISTRIBUTION OF THE MAMMALIA.--In the following pages some of
the principal facts in the geographical range of the orders, families, and
many of the genera of Mammalia will be given. It has been justly observed
by Mr. Sclater that the habitat of an animal is as much a part of its
definition as is its structure or external form. No systematic account of
the Mammalia would therefore be complete without such geographical facts.
But that branch of zoology which is concerned with the past and present
distribution of animals is wider in scope than this. Zoogeography deals not
only with the actual facts in the range of animals, but with the inferences
as to past changes in the relations of land and sea which the facts seem to
indicate, and with speculations as to the place of origin of the different
groups, of which more than hints are sometimes given by their past and
present distribution. In addition to this, the earth can be mapped out into
provinces and regions which are definable by their animal inhabitants. In
the present volume, dealing only with the Mammalia, it will be obviously
impossible to enter fully into the entire subject of zoogeography. All that
will be attempted is a brief general survey of the science so far as it can
be illustrated by the Mammalia. For fuller knowledge the reader is referred
to the treatises mentioned below.[43]

There are certain facts in the distribution of animals which are
commonplaces of knowledge, but which may be set forth with definiteness.
Everybody knows that an animal has a given range: Elephants, for example,
are found in India and certain adjacent parts of Asia, and again in Africa;
the Rhinoceroses have roughly the same range; the Tiger is limited to Asia;
the {79} Jaguar to America, and so forth. The entire expanse of country
which is inhabited by an animal is called its area of distribution. Such
areas are larger or smaller. The Lion ranges over the whole of Africa, a
small part of India, and some neighbouring countries; on the other hand,
the Insectivore _Solenodon_ is limited to Cuba and Hayti, a separate
species to each. Among other groups of animals are instances of an even
more restricted range. There are humming-birds confined to the slopes of a
single mountain, and fishes limited in their range to a single small lake.

A species may be found everywhere within the area of its distribution, or
it may be confined to a number of limited tracts within that area. In this
case it is usual to speak of "stations." In such cases the species in
question is generally suited to some particular kind of environment. Thus
the Otter and other aquatic mammals will only be found where there is
water; and intervening tracts of waterless country will contain no Otters.
Goats and Chamois live only upon mountains; the intervening plains are
destitute of them. This discontinuity of distribution within the area is
very general. But a discontinuity of area is also seen--not so commonly
however; and, indeed, when it does occur, it is a matter of a genus and not
of a species. Thus the Tapir is found in the East Indies on the one hand
and in South and Central America on the other, being absent in the
intermediate tracts.

It is clear that tracts of country eminently suitable for the housing of a
particular mammal do not always possess that kind, or even an allied form.
Africa, for example, possesses no arboreal Anteaters; there are no
Anteaters at all (of the order Edentata) in Australia, though there are
plenty of ants for them to feed upon, and tropical conditions of climate
prevail. But as in these cases the inference may be denied on the grounds
that no experiments exist to prove or to disprove the assertion, the matter
may be better emphasised by such cases as the introduction of the Rabbit
into Australia, and various mammals, such as Goats, into oceanic islands.
The plague caused by the former is a matter of notoriety. But although
climate and conditions and animal inhabitants do not march accurately
together, there is certainly some connexion between temperature and the
range of animals. Mr. Lydekker writes on this point as follows: "The
llama-like animals, respectively known as vicunas and guanacos, are met
with in {80} company on the highlands of the Cordillera in Peru and
Ecuador, but as we go farther south the latter are found on the plains of
southern Argentina and Patagonia, as well as on the island of Tierra del
Fuego at the sea level. Here then is a clear proof of the intimate
connexion existing between temperature and station; the guanaco being an
animal which can only live in cold or temperate climates, finds suitable
conditions for its existence in tropical latitudes solely at a height of so
many thousands of feet, although farther south it is able to thrive at the
sea level." This, however, cannot be pushed too far--the world cannot be
mapped out into areas bounded by parallels of temperature as was once
attempted--since there are plenty of cases like that of the Tiger, which is
as much at home in a tropical jungle as on the icy plains of Northern Asia.

Seeing that there are in many cases no climatic barriers to the spreading
of a given race of animals over a larger area of distribution than it
actually occupies, it becomes important to inquire why there are so many
cases of restriction in range.

It is possible to see, at any rate, three causes which are responsible for
a large number of such cases. In the first place, a given species of animal
must have originated at a certain spot; its multiplication in individuals
must always be a slow matter, since enemies, and untoward events generally,
would conspire to check the natural multiplication by geometrical
progression. A long time might therefore elapse before the species greatly
extended its range. A restricted distribution may therefore, in some cases,
mean a modern race. In the second place, there are definite physical
barriers which check the migration of species. The terrestrial Mammalia
cannot cross wide arms of the sea; that they can and do swim for
considerable distances has been proved in several instances; but, as has
been pointed out, it is unlikely that a purely terrestrial mammal would
voluntarily swim out into an unknown sea. And then if it did, and
successfully reached the opposite side, nothing would happen unless it were
a pregnant female; or, if not pregnant, till a male swam very soon
afterwards in exactly the same direction. Many travellers have told of
floating islands, formed of torn-up trees and brushwood, which have been
seen at the mouths of large rivers, with animal passengers upon them. These
are, however, so much at the mercy of currents and storms, {81} that but
little reliance can be placed on them as a means of transit; besides, here
again, two individuals, or a pregnant female, would be required to effect a
settlement on a foreign shore. The existence of oceanic islands is often
urged as a proof of this inability to cross tracts of sea; even those which
are comparatively near an extensive continent, such as, for example,
Fernando Noronha in the Atlantic, are destitute of mammals (except, indeed,
the ubiquitous Mouse, which is believed to have been carried there, often
in company with the equally widely-spread Rat, in ships). This argument,
however, is not so conclusive as might appear; it doubtless is in the case
of far-distant islands. But the size of the islands has to be taken into
account. For there are islands, such as the Galapagos, or, to take a less
contested instance, some of the islands of the Malagasy Archipelago,
undoubtedly continental, which have an exceedingly reduced number of
mammals. An area of a certain size seems to be a necessity.

The converse of this is in many cases easy to show, that is, the wide range
of animals when there are no marine barriers to stop their spreading. John
Hunter, the celebrated anatomist and surgeon (not often quoted, however, as
an authority upon geographical distribution), observes: "It is a curious
circumstance in the natural history of animals to find most of the northern
animals the same both on the continent of America and what is called the
Old World, while those of the warmer parts of both continents are not so.
Thus we find the bear, fox, wolf, elk, reindeer, ptarmigan, etc., in the
northern parts of both.... The reason why the same animals are to be found
in the northern parts is the nearness of the two continents. They are so
near as to be within the power of accident to bring the animals, especially
the large ones, from one continent to the other either on the ice or even
by water. But the continents diverging from each other southward, so as to
be at a very considerable distance from each other even beyond the flight
of birds, is the reason why the quadrupeds are not the same."

There is no doubt, in fact, that the ocean is the most insuperable of all
barriers to the dispersal of mammals. In a less degree mountain ranges and
deserts are also barriers. The Desert of Sahara is a striking instance to
the point; it separates two exceedingly different faunas. {82}

A third cause of more or less limited range is the barrier due to
competition. If the ground is already taken up, there is no room for new
immigrants. There is obviously a limit to the number of Antelopes or Deer
that can graze upon a given tract of grassy plain. These two groups of
Ungulates illustrate the matter well: the Antelopes are African and Indian,
especially the former, while Africa has no Deer at all; America, on the
other hand, has plenty of Deer but no Antelopes, save the Prong-horn. The
more nearly akin the two species or groups of species are, the fiercer will
be the competition; for a near kinship will at least often imply similar
habits, the need for similar food, and other likenesses which will prevent
both from successfully occupying the same tract of country. The remarkable
fauna of Australia is believed to afford an example of this. In that
country the prevalent inhabitants are the Marsupials. The Monotremes are
found there also, and nowhere else save in New Guinea and Tasmania. The
remaining mammals are inconspicuous; they embrace a few Rodents and Bats,
and the doubtfully indigenous Dingo-dog. Now the Marsupials are fitted to
every variety of life. We have the grazing Kangaroos and Wallabies, the
burrowing Wombats, the arboreal Phalangers, and the carnivorous Dasyures.
In the second place, it is an unquestioned fact that the Marsupials are an
older race than are the existing Eutherian mammals; they were the dominant
mammals during the Secondary epoch. At that time they were more widely
distributed than at present. In most parts of the world they are now
absent, since they have been successfully ousted by the more highly
organised groups of Eutheria. But at that period, when the higher Eutheria
were in the ascendant, Australia and the islands to the north became cut
off from Asia, and thus became freed from inroads of Eutheria, which were
partly prevented by the physical barrier of the sea from effecting a
settlement, and partly perhaps prevented owing to the ground being already
taken up by the Marsupials. Likeness of habit gave the older inhabitants
victory in the struggle for existence.

The general statements that have been here made are in accord with current
opinion upon the factors of geographical distribution. But the past range
of animals appears to be less consonant with the received views. In the
Tertiary {83} period, groups of animals had often a far wider range than at
present. To-day the Rhinoceroses are limited to Asia and Africa, and to
quite limited parts of the former continent. In the past, these animals
were abundant in Europe and North America. Wild Horses now have a range
which is not widely different from that of the Rhinoceroses, save that they
extend into the more northern regions of Asia. Their remains are abundant
both in North and South America. The Hippopotamus, now confined to Africa,
once ranged over Europe, Madagascar, and India. There were plenty of
American and European Lemurs. Elephants were nearly world-wide in their
range; and, in short, restricted distribution seems to be on the whole a
characteristic of animals of the present day.

These statements, however, though perfectly true, must not lead to
erroneous inferences. It is rather impressed upon the reader, in books
which contain sections dealing with geographical distribution, that animals
on the whole occupy more restricted areas at present than in the past.
There are, however, plenty of examples of groups of extinct creatures which
had, so far as we know, quite a restricted range. Thus the Toxodonts were
purely South American, as were the Glyptodonts and some other forms. And,
on the other hand, the Cervidae of to-day are as widely, if not more
widely, distributed than at any other time. The Hares and Rabbits are now
nearly universal in range; the Cats almost so. We meet with Bovidae, even
excluding the Sheep and Goats, in all the four quarters of the globe,
excluding only South America and, of course, Australia. The Camelidae are
still common to both the Old and the New Worlds.

During certain periods of the Tertiary epoch it is true that there was more
similarity between Europe and North America than there is at present. It
would have been quite necessary to unite both into a Holarctic area, such
as is now insisted upon by many; but the reasons for this union would then
have been stronger. The fact is, however, that the closer resemblances were
due to the larger number of families of animals which existed then than
now; these have decayed away from both continents, and allowed the
unlikenesses between the mammalian fauna of both to become evident. But the
likenesses which still survive have led many to associate the two regions
closely together.

So far as the history of a genus or family or larger division {84} can be
traced, it results as a conclusion that from a given area of origin the
group in question migrated in all directions where possible to a varying
degree; it then died out in intervening tracts, or was left only in a
certain part of its former and more extensive area of range.

ZOOLOGICAL REGIONS.--Seeing that each species of animal has its own
definite range, it is clear that the earth's surface can be apportioned
into divisions which are characterised by their animal inhabitants. We
shall divide the earth into realms, which are the largest divisions; then
into regions; and finally into subregions. It must be borne in mind that
the various groups of the animal kingdom are of different ages,
geologically speaking, and have therefore had less or more time, as the
case may be, to settle down into their present distribution, and that
different animals differ greatly in their rate of multiplication, their
power of migration, and their susceptibility to the effectiveness of
various natural and other barriers to distribution. It is not, therefore,
possible to divide the world into realms and regions which shall express
the facts of distribution of the entire animal kingdom. Such divisions,
which are common in text-books of zoology having but a small section
devoted to zoogeography, are at best mere approximations and averages; no
good is gained by taking such a comprehensive view of the matter, as the
essential object of subdividing the earth's surface is thereby lost sight
of. The zoogeographical division of the earth which will be adopted here is
that originally recommended by Dr. Blanford, and now accepted by a number
of authorities. There are three "realms," to which a fourth may perhaps be
added--though on negative grounds, and merely for the purpose of
emphasising the parts of the world to which mammals have not gained access.
The realms are again divisible into regions, at least in the case of one of
them, and the regions may be again separated into more or less distinct
subregions or provinces. The three primary divisions or realms which
contain mammals are the Notogaean, including Australia and certain islands
to the north of it; the Neogaean, or the South American continent and
Central America; the Arctogaean, including the continents of North America,
Europe, Asia, and Africa, together with the adjacent islands, such as the
West Indies, East Indies (exclusive of those which fall within {85} the
realm of Notogaea), and Madagascar; and finally, the realm of Antarctogaea
or Atheriogaea, which embraces New Zealand, the Antarctic continent, and a
series of islands such as South Georgia and Kerguelen, and possibly even
the extreme south of Patagonia. This latter quarter of the globe will need
no further reference, as it has no truly indigenous terrestrial mammalian
inhabitants. We cannot include the Bats in this statement, as their
distribution is due to different powers of extending their range, and to
different barriers from those which govern the range of other groups of
mammals.

(1) Notogaea.[44] This realm is characterised by the exclusive possession
of the Monotremes:--that is to say, one of the two primary divisions of the
Mammalia is absolutely restricted to this area. It contains, moreover, the
vast majority of the Marsupials. Further, the realm of Notogaea is to be
distinguished by the entire absence of the higher mammals, with the
exception of a few small Rodents. (The Bats are ignored for the reasons
stated, and the Dingo is believed to have been an importation.) It cannot
be disputed that this is a very distinctly-marked area of the earth's
surface.

(2) Neogaea. The continent of South America has no Monotremes and only a
few Marsupials, all of which, with the exception of _Caenolestes_, belong
to the Polyprotodont division of that order, and to a peculiar family,
Didelphyidae. The recent discovery of other fossil Marsupials, however, to
some extent favours Huxley's view that Neogaea and Notogaea form one realm
as opposed to the rest of the world. Besides this, Neogaea possesses the
Edentata, which are found nowhere else;--that is, the division of the
Edentata to which the name is now restricted by some authorities. It is
also characterised by the nearly entire absence of the important order of
Insectivora; and, as minor marks of distinction, by the absence of
Antelopes, Oxen and Sheep, of the Ichneumon tribe, of Horses, and of
Lemurs. It has the exclusive possession of the Hapalidae and Cebidae, and
of several families of Rodents.

(3) Arctogaea. This vast realm is clearly capable of subdivision into four
regions, which will be considered in detail later. In the meantime the
points of likeness between these subdivisions is more marked than are
either the resemblances or the {86} differences of any one of them to
either of the two realms which have just been defined. The two realms that
have been discussed retain their distinctness from each other and from
Arctogaea for a considerable way back into the Tertiary period. It is not
until we reach very early Tertiary times that Edentates are met with in
North America; and then it cannot be regarded as absolutely settled that
the Ganodonta are really the forerunners of the Armadillos, Sloths, etc.
Nor do we find Marsupials in Europe until far back in time, and at a
corresponding period in North America. Indeed the fauna of South America in
late Tertiary times was even more distinct than it is now; for then we had
confined to that region the Toxodonts, Glyptodonts, _Macrauchenia_, and
other forms, while in Australia there were still Marsupials. In late
Tertiary times Europe and India were by no means so distinct from Africa as
they are to-day. North America does not resemble the Old World quite so
much as the subdivisions of the Old World resemble each other; but, as will
be pointed out later, there are and were very substantial agreements. The
Elephants, Rhinoceroses, Giraffe, Hippopotamus, _Orycteropus_, are now
distinctively African or Indian animals; but all these genera, or at least
families (in the case of the Giraffe), have occurred in Europe during quite
recent times. _Lycaon_ indeed, now confined to Africa, is thought to have
had a European origin from its occurrence in caves there. The Hyaena and
the Lion, certain members of the Horse tribe, Apes, and other animals, were
also but are not now European.

India again, and the Oriental region generally, once possessed the
Hippopotamus, the Chimpanzee, Giraffidae, the Antelopes, _Cobus_,
_Hippotragus_, _Strepsiceros_, and _Orias_, which are now purely African
animals. It shares at present with the Ethiopian region the Catarhines,
including the Anthropoid Apes, the Lemurs, Tragulina (the genus
_Dorcatherium_ is also known from fossils in India), _Manis_, _Hyaena_, the
Cheetah, Elephant, Rhinoceros, and the Ratel. There is, in fact, no order
of mammals which is now absent from one of these three regions though
present in the others, save the Lemurs, and they occurred in past times in
Europe. The Tapir of India is known fossil in Europe, and the latter
continent had its Monkeys and even Anthropoids. On the other hand, North
America is more distinct. It has no Lemurs, Apes, Elephants, Rhinoceroses,
Tapirs, Old World Edentates {87} (Effodientia), Viverridae, Horses, or
Antelopes, excepting _Antilocapra_, a type of a separate division of
Bovidae. But since several of these groups have been represented in recent
times, no primary line of division can be profitably drawn.

Arctogaea as a whole may be characterised by both negative and positive
characters. As negative features may be mentioned;--the entire absence of
Edentates (_Necrodasypus_ of Filhol is rather doubtful, see p. 164, n.),
though a few crept up into the Nearctic region from Neogaea during past
times; and of Hapalidae, Cebidae, and Marsupials, except an Opossum in
North America. This realm has, on the other hand, all the Lemurs, all the
Insectivores with the exception of the West Indian _Solenodon_, all the
Proboscidea, Rhinoceroses, Horses, Deer, Antelopes, the last group
including the Oxen and a variety of other important families. It is in fact
the headquarters of all the Eutheria with the exception of the Edentata and
Marsupials.

The subdivisions of this realm have been variously effected. The classical
subdivisions are of course those of Mr. Sclater, who would recognise (1)
the Nearctic, North America; (2) the Palaearctic, including Europe,
Northern Asia, and Japan; (3) the Oriental, including Asia south of the
Himalayas and the islands of the Malay Archipelago as far east as the
Australian region; and (4) the Ethiopian, _i.e._ tropical Africa and
Madagascar. Some would alter this by uniting America and the north of the
Old World into a Holarctic region, separating off the southern parts of the
North American continent into a Sonoran region. To some, the claims of
Madagascar to form a separate region are convincing. To distinguish the
boundaries of the several regions is a difficult task; they dovetail into
each other on the frontiers with the complex curves of a puzzle-map. The
difficulty has been grappled with by the suggestion of intermediate
transitional areas; but this proceeding really doubles the difficulty, for
there are then two frontiers to delimit in each case instead of only one.
The animal inhabitants must be expected to mingle somewhat at the lines of
junction of one region with another.

The Sonoran region does not appear to us to have great claims to
recognition. It shows a mingling of southern with northern forms exactly as
might be expected. An Armadillo and _Didelphys_ have, as it is believed,
invaded it from the Neogaeic realm; it possesses also the South American
genera, _Dicotyles_, _Nasua_, {88} _Conepatus_, _Sigmodon_. On the other
hand, the Sonoran genera _Antilocapra_, _Cynomys_, _Procyon_, and the
Insectivora _Blarina_ and _Scapanus_, extend further north. Peculiar to
this region are only six genera of Rodents, which seems an insufficient
reason for raising the Sonoran province to the dignity of a region.
Considered from the point of view of numbers of peculiar forms, the
Thibetan subregion has more claims to distinction as a region; for confined
to that area we have the genera _Nectogale_, _Aeluropus_, _Eupetaurus_,
_Pantholops_, _Budorcas_; while by slightly extending its limits, a number
of other peculiar forms might be added. Madagascar has distinctly more
claims to regional division. Absolutely confined to it are eleven of the
seventeen existing genera of Lemurs, the family Centetidae among the
Insectivora, which contains seven genera, and another recently discovered
and peculiar genus, _Geogale_; it has six peculiar genera of Viverridae; it
has five peculiar genera of Rodents. In addition to this it is negatively
characterised by the absence of the following typical African animals,
Felidae, Proboscidea, Rhinocerotidae, Equidae, Monkeys, etc. It seems to be
impossible to avoid allowing the rank of a region to this part of the
world.

In separating the Nearctic from the Palaearctic region, stress must be laid
rather upon the absence of Asiatic and European forms from North America
than upon the existence in the northern half of the New World of many
peculiar forms. Peculiar to the Nearctic are the Goat genus _Haploceros_,
the Rodents _Erethizon_, _Zapus_, and the family Haplodontidae. The Mole
genus _Condylura_ is also restricted to this part of the New World. Even so
it has more peculiar forms than the Sonoran. If we add to this the absence
of Horses, Antelopes except _Antilocapra_, Pigs, Hyaenas, etc., there are
strong grounds for retaining this division. It must be agreed, however,
that it comes rather nearer to the Eurasian district than the latter does
to the Oriental.

The Oriental region has many characteristic animals. It has among the
Anthropoid Apes the Orangs and Gibbons; of Old World Apes it has confined
to its own area the genera _Semnopithecus_ and _Nasalis_. Of Lemurs there
are _Loris_ and _Nycticebus_, and _Tarsius_, representing a family of that
order, or even a sub-order. The Galeopithecidae are entirely Malayan. There
are many Rodent, Carnivorous, and Insectivorous genera; the Rhinoceroses
and the Elephant of this region differ from those of Africa. {89}
_Tragulus_ concludes a sample from a very rich list of peculiar forms.

The Ethiopian region has also its Anthropoids, the Gorilla and the
Chimpanzee, but they belong to genera or a genus different from those which
include the Oriental forms. There are five peculiar genera of
Cercopithecidae. The Lemurs restricted to this region are _Galago_,
_Perodicticus_ and _Arctocebus_. The peculiar Insectivorous families
Macroscelidae and Chrysochloridae are only found here, besides many other
peculiar genera. Africa is especially the home of Antelopes, and the
Giraffe is not found now outside its borders. The Elephant and the
Rhinoceroses are of different species from those of India. There are many
peculiar Rodents and Ungulates.

       *       *       *       *       *


{90}

CHAPTER III

THE POSSIBLE FORERUNNERS OF THE MAMMALIA

The relationship of Mammals to Vertebrates lying below them in the scale,
their origin in fact, is a much-debated question, with many attempted
solutions. To enter into this large question in detail would involve a
great deal of useless statement of arguments founded upon misleading or
upon quite inaccurate "facts." It will perhaps be sufficient if we reflect
here the current view most in vogue at the present, _i.e._ that which would
refer the Mammalia to reptiles belonging to the extinct Permian and
Triassic group of the Theromorpha (also called Anomodontia). These have
been explored lately to a very large extent, and chiefly by Professor
Seeley.[45] The very fact that a genus _Tritylodon_, only known by the
forepart of the skull, has been called Mammalian and Anomodont by various
authors, shows at least the difficulty of differentiating the two groups
when the material for study is imperfect. As a matter of fact these
Theromorpha are without doubt reptiles; they show, for example, a lower jaw
formed out of several distinct pieces, of which the articular articulates
with a fixed quadrate on the skull. They possess the characteristic
reptilian bones, the "transverse," the pre- and post-frontals, and there
are various other points of structure which leave no room for doubt as to
their truly reptilian nature. There are, however, numerous indications of
an evolution in the mammalian direction in all parts of the skeleton, to
the more important of which some reference will be made here. It may be as
well to clear the {91} ground by mentioning the fact that among the
Theromorpha four distinct types of reptiles are included, which are
considered to form four orders, _i.e._ the Pareiasauri, the Theriodontia,
the Anomodontia (Dicynodontia), and the Placodontia.

The first of these divisions includes what seem to be basal forms. These
reptiles show numerous points of likeness to the Amphibian
Labyrinthodonts.[46] On the other hand the third division, that of the
Dicynodontia, are highly-specialised Theromorpha, from which no further
evolution would appear to have been possible. Thus the dentition was either
completely lost, or reduced to tusks as in _Dicynodon_. We need not
therefore concern ourselves in the present volume with these Anomodonts. It
is with the Theriodonts that our business lies. The very name, be it
observed, is aptly chosen on the hypothesis to be explained here; but it is
not only in the teeth that these reptiles show likenesses to the Theria or
Mammals, but in almost every feature of their organisation. Unlike other
reptiles, the Theromorpha in general were lifted comparatively high above
the ground on legs of fair length and of mammalian relationship in the
position of the segments of the limbs. The typical reptile grovels upon the
earth with legs sprawling out, as indeed the very name suggests. One bar to
the Theriodonts being on the direct line of mammalian ancestry has been
urged as a preliminary difficulty, and that is their large size. The
earliest undoubted mammals were small creatures, comparable to a Rat or a
Mouse in size; whereas a good-sized Bear or a Wolf is a better standard of
size for some of the best-known genera of Theriodonts. It has, however,
been quite permissibly suggested that living in company with these large
Theriodonts were less obtrusive genera, from which the mammals might have
sprung. It is so familiar a fact that a given group of animals generally
contains giants, dwarfs, and members of intermediate size, that this
suggestion may almost be accepted as a fact. It need at least present no
difficulties to us in our comparisons.

The most salient "mammalian" feature of the Theriodonts is the heterodonty
of the teeth, the pattern of the "molars," and the limited number which
constitute the series. The fact, too, that they are limited to the dentary
bones below and to the {92} maxillae and the premaxillae above, is a _sine
qua non_ for mammalian comparison. In the more basal Theromorpha the teeth
are not so limited in position. Finally, to complete the remarkable
mammalian resemblance of the teeth of these reptiles, it must be mentioned
that in _Tritylodon_ and _Diademodon_ the roots of the molars, as we may
fairly term them, though not actually divided after the mammalian fashion,
were deeply marked by a groove, which suggests an incipient division or a
fusion of two distinct roots. Some of these facts of structure may now be
considered in further detail. As to the incisors and canines, it is
sufficient to say that the numbers of the former, and the shape of the
latter, are in perfect consonance with a derivation of the Mammalia from
this group. The molar series can be divided into premolars and molars, at
least in so far as regards their shape; for the anterior teeth are often
smaller and less complicated than those which follow, as is often the case
with the two series in mammals. The molar series also consist of teeth in
close apposition to each other and separated from the canines by a
diastema, which is a character of mammalian teeth. The fact that in the
reptile _Cynognathus_ and the mammal _Myrmecobius_ there are nine of these
molar teeth in each half of each jaw is perhaps not a point upon which it
is desirable to dwell with too much weight; but the general fact that the
molars are further reduced in some genera of Theriodontia than in that
which has been mentioned, is clearly a matter of significance when the
ancestry of the mammals is under consideration.

The most interesting fact about the molar series in the Theriodontia is
that we meet with the two types of molars that occur in the mammals.
_Cynognathus_ and other genera have molars which consist of a main cusp,
and of one cusp before and one after the main cusp; in fact these teeth are
triconodont as in certain early mammals, a state of affairs which is
believed by the "trituberculists" (see p. 56) to have preceded the
tritubercular tooth. There are also "multitubercular" teeth, especially
well developed in _Tritylodon_, where they exactly resemble those of
certain Multituberculata, and whose structure originally led to the placing
of _Tritylodon_ among the mammals of that group. If there is any question
about the mammalian nature of this fossil, there remain several other
Theriodontia in which the multituberculism is well marked. It is so in
_Trirhackodon_ {93} and in _Diademodon_ for instance. This incidentally
lends some support to the idea that the Mammalia have been evolved from two
sources, a way of looking at the origin of the group that will coincide
with the views of some authors like the late Dr. Mivart, and will at the
same time reconcile the trituberculists and the multituberculists. For we
should then assume that the Eutheria and Triconodontia had originated from
some such form as _Cynognathus_; and the Multituberculata and the existing
Monotremes from some form like _Diademodon_. It is not of great use to
point out that _Diademodon_ is really of the trituberculate pattern,
because in its molars, though multituberculate, the trituberculate main
cones can be recognised; for that state of affairs could just as well have
been brought about by a reduction from the multituberculate type. The skull
of these Theriodonts shows some well-marked approximations to the mammalian
type. There is in the first place a commencing consolidation and reduction
of the individual bones, which is so distinguishing a feature of the
mammalian skull as opposed to the skull of lower vertebrates. In
_Cynognathus_ the postorbital is fused with the jugal, and the
supratemporal with the squamosal, forming apparently one bone. In the lower
jaw the splenial is often reduced to the thinness of paper, thus indicating
a commencing disappearance. In many Theromorpha the squamosal shares
largely in the formation of the articular facet for the lower jaw,
obviously an important mammalian characteristic; this is brought about by
the reduction of the quadrate, which latter bone, moreover, acquires in
certain particulars the appearance of the mammalian malleus, with which it
is, according to many, homologous. But this subject has been already dealt
with on page 26. A very pronounced likeness to the mammalian skull is that
there are two occipital condyles. That this has been brought about by the
further development of a tripartite condyle such as occurs in tortoises,
and that by the suppression of the basi-occipital part, does not affect the
resemblance to the mammalian skull; in fact it explains the origin of two
condyles from the typical reptilian single condyle, and disposes of the
necessity for believing, with Huxley and others, the Amphibia to be on the
main line of mammalian evolution on account of their two condyles. The
general aspect of the skull in _Cynognathus_ has been {94} compared to that
"of _Thylacinus_ or _Dissacus_." No one can examine the actual sketches of
the skull of that Theriodont without endorsing that opinion. As a curious
detailed point of likeness to certain Mammalia may be mentioned "a small
descending process of the malar bone, which may be a diminutive
representative of the descending element of the malar seen in _Elotherium_,
_Nototherium_, _Diprotodon_, _Macropus_, certain Edentata, such as
_Glyptodon_, _Megatherium_, _Mylodon_, _Bradypus_, but unparalleled so far
as I am aware in fossil reptiles." (Osborn.) The zoologist cannot help
being impressed with the significance of small details of similarity, which
do not seem to be due in any way to surrounding conditions of life, and
thus referable to mere convergence, like the fish-like form of Whales and
Seals.

The rest of the skeleton of the Theriodontia is by no means so well known
as the skull and teeth. But from what is known, other mammalian characters
can be pointed out. Perhaps the most striking mammalian feature is to be
found in the scapula of _Cynognathus_. It is in this creature somewhat
narrow and elongated; but it has a well-marked spine, ending in a hooked
acromion. Now it is to be noted in support, so far, of the diphyletic
origin of mammals, that in the Monotreme, as in Whales indeed, the spine
forms the anterior border of the scapula, and is coincident with it, there
being thus no prescapula at all in the Monotreme, and only a trace of it in
certain Whales.[47] Whether the multituberculate _Tritylodon_ or
_Diademodon_ had a scapula after the Monotreme pattern is not known; but it
is clear that the scapula of the triconodont _Cynognathus_ is quite after
the pattern of the Eutherian scapula. Furthermore, Professor Seeley is of
opinion that the coracoid was relatively small, and indeed smaller than the
same bone in Edentates, and _a fortiori_ than in Monotremes. Another fact
of structure which points also, possibly, in the direction of a diphyletic
origin for the Mammalia, is the double-headed ribs of _Cynognathus_. As is
well known, the ribs of the Monotremata have only the central head, the
capitulum.

As a general mark of affinity with mammals the reduction of the intercentra
in _Cynognathus_ may be noted, and also the existence of a small though
perfectly obvious obturator-foramen, separating the pubis from the ischium.
There are further details {95} which tend in the same direction. And we
shall probably not go far wrong in the present state of our knowledge if we
assign the origin of the mammals to some type which would be included in
the order Theriodontia or at least in the sub-class Theromorpha.

       *       *       *       *       *


{96}

CHAPTER IV

THE DAWN OF MAMMALIAN LIFE

The animals that we considered in the last chapter, though showing certain
unmistakable likenesses to the mammals, are nevertheless unquestionably not
mammals but reptiles. In the Triassic strata, however, we first meet with
the remains of undoubted mammals. The Mammalia first appeared upon the
earth in a tentative and hesitating way: they had not cast off many of the
characters of their supposed reptilian forefathers; they shrank from
observation and destruction by their small size, and apparently, so far at
any rate as their teeth afford a clue, by an omnivorous diet. The world
abounded at that period in large and carnivorous reptiles, which may indeed
have been the principal enemies with which the first mammals had to cope.
These early mammals lingered on to so late a period as the Eocene; but the
majority of the genera were Triassic, Jurassic, and Cretaceous. Certain of
the primitive mammalian forms have been referred to the Marsupials, and
their resemblances to the Monotremata have also been pointed out. The
current view of the present time, however, is that they form a special
order, which may possibly have embraced the ancestors of both Marsupials
and Monotremes; for it is reasonable to explain in this way the combination
of characters of these two orders which they present. For this group the
name Allotheria has been proposed by Marsh, and Multituberculata by Cope;
the latter term is the less suitable, in that the Monotremata
(_Ornithorhynchus_) are also "multituberculate." The group is known in a
very imperfect fashion. The remains are but few and fragmentary; and for
the most part we have only a few teeth to speculate upon. This is natural
enough, for the harder teeth might easily be supposed to {97} have resisted
the decay which would more readily affect the softer bones. Where there are
bones it is frequently the lower jaw alone which has been preserved for
us--a bone which has also been preserved in the case of some of the
contemporary Marsupials.

It has been pointed out (from the observation of dead dogs floating in
canals) that the lower jaw is occasionally detached from the carcase. It is
the most readily separable part which contains a skeleton. It may be,
therefore, that the remains of these early mammals, floating down some
river to the sea, may have lost their jaws while in the river, or at
furthest in the shallow waters of the sea, the rest of the carcase floating
out to a greater distance, and being finally entombed in the stomach of
some carnivorous fish, or in the mud at the bottom of a deep ocean, which
has never since seen the light.

The characters of this group are really more those of the Monotremata than
of the Marsupials. The undoubted likeness which their molar teeth show to
the temporary teeth of the Platypus have already been commented upon. Like
the Monotremes the Allotheria appear to have possessed a large and
independent coracoid; the evidence for this rests upon the discovery of the
lower end of a scapula of _Camptomus_, a Cretaceous genus from North
America upon which there is a distinct facet for the articulation of what
can have been nothing else than a coracoid. On the other hand they differ
from the Monotremata by the presence of incisor teeth which were
Rodent-like in form, and not very different from those of certain
Marsupials. This point of difference cannot be regarded as of very
first-rate importance; no one would relegate the Sloth and the Armadillo to
different orders on account of their tooth differences, which are about on
a par with those to which we have just referred. It seems indeed likely
that it will be ultimately necessary to rub out the boundary line which now
divides the Allotheria and the Monotremata.

The Plagiaulacidae are unquestionably mammals, and they are placed by most
naturalists in this at present uncertain group of Multituberculata, which
will be retained here in deference to the distinguished authorities who
have instituted the group, though there are but few characters by which it
can be defined. This family though appearing in the Trias, extends down in
time to the Eocene. The type-genus, that which has given its name to {98}
the family, is _Plagiaulax_. As it is not Triassic, the consideration of
its characters will be deferred until later. _Microlestes_ is a Rhaetic
genus, known from rocks in Germany and England; but it is entirely based
upon molar teeth. _M. antiquus_ has a two-rooted molar of an elongated form
with a row of tubercles on either side of a median groove, which traverses
the long axis of the tooth. To some extent the teeth of the ancient form
resemble those of _Ornithorhynchus_. _Microlestes_ has been sometimes
spoken of as a Marsupial, but Mr. Tomes[48] has found that it does not show
one very universal character of the Marsupial teeth: it has not those
continuations of the dentinal tubes which traverse the enamel in all
Marsupials that have been examined with the sole exception of the Wombat.

The rarity of the remains of mammals in these earliest rocks of the
Secondary epoch has been accounted for in another way from that which has
been suggested above. It may be that the group Mammalia was not evolved in
Europe at all, and that the stray remains which have been found in that
continent represent the fragmentary remnants of a few scattered immigrants
which heralded the later invasion of more numerous genera during the
Jurassic period.

THE MAMMALS OF THE JURASSIC PERIOD.--Some of the Allotheria or
Multituberculata described in the last section occur in the rocks of this
early part of the Secondary epoch. They are doubtful in position, as
already stated; some of them indeed, as for instance _Tritylodon_ and
_Dromatherium_, are possibly not mammals at all, while the remainder
probably belong to a non-existent order of mammals. Along with these
dubious creatures are the fragmentary remains of small animals which are
not merely mammals, but in all probability definitely Marsupials. It is
true that here again we have little beyond lower jaws and teeth to deal
with; so that there may be less certainty in referring them to the
Marsupials than appears to be the opinion of the majority of
Palaeontologists.

Professor Osborn in fact considers that the Mesozoic mammals consist of
three groups: (1) The Multituberculata, including the Bolodontidae,
Stereognathidae, Plagiaulacidae, Polymastodontidae, and possibly the
Tritylodontidae (which, however, are regarded by him and by others as more
probably reptiles of the {99} Theromorphous group). (2) The Triconodonta,
which were Marsupials, though in all probability with a complete succession
of teeth and with an allantoic placentation. This group will include the
genera _Phascolotherium_ and _Amphilestes_, as well as _Triconodon_ and
_Spalacotherium_. Finally we have (3) the Trituberculata (or Insectivora
Primitiva) with the genera _Amphitherium_, _Peramus_, _Amblotherium_,
_Stylacodon_, and _Dryolestes_.

We shall take these three groups in order. The Multituberculata have
already been to some extent defined, if such a word can be used to express
the summation of the very scanty information at our disposal. Of this
group, _Plagiaulax_ is a genus which occurs in the Purbeck beds; it is only
known by lower jaws implying an animal of the size of a Rat or rather
smaller. The jaws have in front a large incisor which looks Rodent-like,
and also like those of the Diprotodont Marsupials; but it is held that
these teeth did not grow from persistent pulps, and there is in any case no
anterior thickened coating of enamel. Canines are absent; the diastema is
followed by four premolars increasing progressively in size and possessing
somewhat complicated grinding surfaces. These surfaces are formed by
several obliquely-set ridges. The succeeding teeth are termed molars on
account of their difference in structure, and there are but two of them on
each side. The molars are of a pattern common in the Multituberculata; the
centre is hollowed, and the raised rim is beset by tubercles. Other
Jurassic genera of Multituberculates are _Bolodon_, _Allodon_, and
_Stereognathus_. All of these possess the same multituberculate molars.

Of the Triconodonta the type-genus is _Triconodon_. This genus is better
known than most Jurassic mammals, since both the upper and the lower
dentition have been described. It appears to have possessed the typical
Eutherian dentition of forty-four teeth, to which a fourth molar is added
in some species. The great difference between the molars and premolars
argues a complete tooth-change. The genus is American as well as European.

_Spalacotherium_ has more molars, five or six.

_Phascolotherium bucklandi_, on the other hand, is a much older type in the
form of its teeth. There are, however, not so many of them as in
_Amphitherium_; _Phascolotherium_ has but two premolars and five molars,
making a total of forty-eight teeth. The teeth are of the triconodont form,
the three cusps being in line, and the middle one the largest. {100}

_Amphilestes_ has teeth of the same pattern but has more of them, the
premolars and molars being respectively four and five. All these animals
had the lower jaw inflected. Whether they are all Marsupials or not, it is
clear that _Phascolotherium_ and _Amphilestes_ should be united and placed
away from _Amphitherium_ on account of the more primitive form of their
teeth.

We next come to the Trituberculata.

Among the most celebrated of these remains are a few jaws discovered in the
Stonesfield slates near Oxford, and examined by Buckland, Cuvier, and some
of the most eminent naturalists of the beginning of the last century. These
jaws have been lately submitted to a careful re-examination by Mr.
Goodrich,[49] who has increased our knowledge of the subject by exposing
from the rocky matrix in which the jaws lie fresh details of their
structure; it is probable therefore that now all that there is to be learnt
from these specimens has been recorded.

_Amphitherium prevostii_ was a creature about the size of a Rat. Its jaw
was first brought to Dean Buckland about the year 1814, and described six
years later. Buckland thought the jaw to be that of an Opossum, an opinion
in which Cuvier concurred. The jaw, however, is marked by a groove running
along its length, and this groove was regarded by de Blainville as evidence
of the composition of the jaw out of more than one element, which would
naturally lead to its being regarded as the jaw of a reptile.[50] This
species and another named after Sir Richard Owen have a dental formula
which, like that of the Marsupials, is large as compared with that of the
Placental mammals; it runs: I 4, C 1, Pm 5, M 6--_i.e._ 64 teeth
altogether. This is a larger number than we find in any existing Marsupial.
But as in Marsupials, and in certain Insectivora also, the angle of the jaw
is inflected. These teeth are of the tritubercular pattern with a "heel."
They are in fact closely like those of the living _Myrmecobius_; but not,
it should be remarked, unlike those of certain Insectivora.

THE MAMMALS OF THE CRETACEOUS PERIOD.--At one time there was a totally
inexplicable gap between the Jurassic and the basal Eocene, a series of
strata which occupy an enormous expanse of time in the history of the earth
having appeared to {101} be devoid of mammalian remains. This gap, however,
has been filled up by the discovery of mammalian remains in the North
American Laramic formation, which seems to be clearly of Cretaceous age.
Furthermore, it is held by some that the Purbeck beds are more properly to
be placed with the Cretaceous, which would then necessitate the
consideration under the present heading of some of the types already dealt
with; and if, as is suggested in the following section, the lowest
so-called Eocene beds are really referable to the Cretaceous, there is no
lack of mammalian remains in that period. And, moreover, it was in that
case the Cretaceous period which witnessed the evolution of the existing
orders of Placental mammals. Otherwise the mammalian remains of the
Cretaceous agree with those of the Jurassic. We find remains of the
Multituberculata in fragments of Plagiaulacidae and Polymastodontidae.
_Ptilodus_ is a genus which has two premolars; and _Meniscoessus_ is
another multituberculate from the same Laramic formation. The other
detached fragments of mammals are thought by Osborn to represent both
Placentals and Marsupials.

THE MAMMALS OF THE TERTIARY PERIOD.--Unless the lowest beds of the earliest
Tertiary period, the Eocene, such as the Torrejon of North America, should
be in reality referred to the Cretaceous, there is no evidence that the
modern groups of Mammalia existed before the present epoch of the earth's
history. It is probable, however, that the Eutheria as a group were
Mesozoic. The fossil jaws that have been considered in the last chapter may
quite probably be primitive Eutherians, or even divisible, as believed by
Professor Osborn, into Marsupials and Insectivores. In the Tertiary,
however, apart from the question as to the nature of the Puerco and
Torrejon formations, and as to certain South American strata whose fossil
contents have been investigated by Professor Ameghino, we find the first
traces of mammals definitely referable to existing orders, or to be
distinctly compared with existing orders. Since, however, representatives
of types which have obvious relationships to modern types appear in
considerable profusion in the very earliest strata of the Eocene, it seems
clear that much remains to be discovered in beds earlier than these.
Confining ourselves, however, to facts and to comparisons which can be made
on more than a few lower jaws and scattered teeth, which is practically all
that we {102} possess of earlier mammals, we must arrive at the general
conclusion that two of the existing larger groups of the Eutherian,
non-Marsupial, mammals were differentiated at quite the beginning of the
Eocene, and were represented by forms from which it is possible to derive
at least the existing Carnivora, Insectivora, Artiodactyla, and
Perissodactyla. These were the Creodonta and the Ungulate Condylarthra. In
addition to these we may enumerate as very early types the Lemuroidea,
represented by such forms as _Indrodon_ in the New World, and (though
later) by _Necrolemur_, etc., in the Old World, and the Edentata, if we are
to allow as their ancestors the Ganodonta.

The early Eocene strata also contain representatives of at least one order,
the Amblypoda, which increased subsequently, but has died out without
descendants, unless we are to believe with some that the Elephants are to
be derived from these Eocene "pachyderms." In later Eocene times the great
majority of the existing orders, and even subdivisions of orders, are to be
met with; and there are in addition such totally extinct orders as the
Typotheria, Ancylopoda, and Tillodontia. Coupled with this gradual
specialisation in the orders of Eutherian mammals, there is naturally a
vast increase in the number of generic and family types. This culminates
perhaps in the Miocene, from which time there has been a gradual decline in
mammalian variety, so that it is justly said that we live now in an epoch
which is impoverished of mammals. This gradual decay has persisted until
to-day, as is witnessed by the extinction of the Rhytina and the Quagga,
and the growing rarity of the White Rhinoceros and the American Bison.

The early Eutherian stock consisted of small mammals with small heads and
slender, long tails. The limbs were pentadactyle, ensheathed in claws or
broader hoofs. The fore-limbs may have been partly prehensile. The teeth
were forty-four, completely differentiated into incisors, canines, molars,
and premolars; and there appears to have been a complete diphyodontism. The
canines were not greatly enlarged, and no diastema separated any of the
teeth. The molars were bunodont or of a more cutting pattern, with some
five or six tubercles. These animals were, moreover, very small-brained.
This early stock is represented by Creodont and Condylarthrous animals, the
exact boundaries between which are hardly marked in the {103} very early
types. Professor Osborn has argued that from this early Eutherian stock
there were two waves of progress, or, as he expresses it, "two great
centres of functional radiation."[51]

The first was largely ineffective, the second has produced all the
Eutherian orders of to-day. These two divisions are termed by him
"Mesoplacentalia" and "Cenoplacentalia." The first division embraces the
Amblypoda and their descendants the Coryphodonts and Dinocerata, many of
the Condylarthra, the bulk of the Creodonts and the Tillodonts. These
creatures persisted for a time, but died out in the Miocene. They were
mainly distinguished by the smallness of their brain; the great
specialisation of structure which they exhibit having left that organ
unaffected, and therefore tending in the long run to render them unable to
cope with changes in the inorganic and organic world. The successful
division of the primitive Eutheria comprises the groups which exist at the
present day, and is not connected directly with those small-brained
Mesoplacentals; it has apparently originated, however, from the least
specialised of their ancestors. Professor Osborn thinks, moreover, that the
Lemurs and the Insectivores are persistent descendants of the earlier wave
of Eutherian life. It appears in fact as if Nature had created the existing
Ungulate, Unguiculate, and other types on a defective plan, and, instead of
mending them to suit more modern requirements, had evolved an entirely new
set of similarly-organised types from some of the more ancient and plastic
forms remaining over. The Marsupials may be the only group of the early
wave remaining, and they have been able to hold their own for the
geological reason that Australia was early cut off from communication with
the rest of the world. That they are disappearing seems to be shown by
their gradual diminution as we pass from Australia towards the continent of
Asia, through the islands of the Malay Archipelago. Competition has here
decimated them, as it may do in the remote future in Australia.

It is often said, but with some looseness of statement, that ancient
quadrupeds are huger than their modern representatives. This statement is
partly true in fact, but largely wrong in implication. For it suggests
that--and the suggestion is often expressed in books that are not
authoritative--huge animals {104} have left a dwarfish offspring; that
there were giants of old, and that there is a puny race to-day. As a matter
of fact, the study of the gradual evolution of the early Tertiary Mammalia
into their descendants of later times shows very plainly the truth of this
interesting generalisation: That the primitive types were all small
creatures, and that in those instances where we can trace a pedigree, there
was a gradual increase in size up to a point where greater increase led to
extinction. We point out later on a number of facts illustrating this
matter in detail. It has been ascertained, for instance, that the pedigree
of the Horses, the Camels, the Rhinoceroses, and many other groups,
commences with small forms and culminates in large ones. It may be urged
that such animals as the Tapir are to-day smallish forms, and that related
to them in the past were the gigantic Titanotheres; but in this and similar
cases it will be found that the extinct giants were not in the direct line
of pedigree, but represented side-branches which waxed huge on their own
account and then disappeared.

       *       *       *       *       *


{105}

CHAPTER V

THE EXISTING ORDERS OF MAMMALS

PROTOTHERIA--MONOTREMATA

Apart from those creatures whose fragmentary remains have been considered
in the last chapter, and which belong to the earliest of mammaliferous
strata, the remains of Mammalia are all referable to existing orders. In
the pages which follow we shall therefore deal with the actual
representatives of living families side by side with their extinct
relatives. The existing orders of Mammalia, together with those of their
fossil allies, can be plainly divided into two great subdivisions, or, as
we shall term them, sub-classes; the Mammalia as a whole being termed a
class of the Vertebrata comparable with the class Reptilia, etc. It has
been usual, owing to the initiative of Professor Huxley, to divide the
Mammalia into three divisions of primary importance. We shall adduce
reasons later for not accepting this mode of division, but that which
allows of only two primary divisions. These two divisions are (1)
Prototheria and (2) Eutheria. Whether the Multituberculata, Trituberculata,
and Triconodonta, considered in the last chapter, are really to be
distributed among these two sub-classes is a matter upon which it is
possible to form an opinion, but not to dogmatise. The Prototheria stand at
the base of the mammalian series, and present many likenesses to the
Sauropsida; the Eutheria are the animals which are most fully
differentiated as mammals. We shall commence with

SUB-CLASS I.--_PROTOTHERIA._

To this group belongs the order Monotremata, and possibly also the
so-called Allotheria or Multituberculata. As, however, {106} the latter are
only known from very fragmentary remains, which are not sufficient to
determine the systematic position of the animals of which they are
fragments, I have not thought it worth while to attempt a serious
definition of the order Multituberculata. I have introduced a short account
of the principal facts which are known concerning the creatures grouped
together under this name into the historical sketch of the progress of
mammalian life in Chapter IV. As to the Monotremata, there is no question
that they are entitled to rank in a group equivalent to that including all
other mammals of which we have sufficient knowledge to construct a
classificatory scheme. There have been, indeed, naturalists, such as
Meckel, who would altogether deny the mammalian rank of these creatures.

The Monotremata or Ornithodelphia may be thus defined:--

Mammalia with no teats, but with a temporary pouch in which the young are
hatched, or to which they are transferred after hatching, and into which
open the ducts of the mammary glands. An anterior abdominal vein, or at
least the membrane supporting it, persists throughout the abdominal cavity.
Heart with an incomplete and largely fleshy right auriculo-ventricular
valve. Brain without a corpus callosum. Shoulder girdle with a large
coracoid reaching the sternum; clavicles and an interclavicle present.
There are "marsupial" or epipubic bones attached to the pelvis. Vertebrae
with no epiphyses for the most part. Ribs with only capitulum and no
tuberculum. Mammary glands of the sudoriparous and not the sebaceous type
of epidermic gland.[52] Oviparous, with a large-yolked and meroblastic
ovum, enclosed within a follicle of two rows of cells.

To call these animals Mammalia is of course an abuse of the meaning of that
word in one sense, but it is not in another; since the pouch of these
Monotremes is, as has been explained elsewhere (p. 16), the real equivalent
of a teat, and not of the pouch of the Marsupials.

The most salient characteristic of this group of mammals in the estimation
of their position in the vertebrate series is not so much the fact that
they are oviparous as that the eggs are large-yolked, and develop
therefore, so far as regards their early stages, after the fashion of the
egg of a reptile. The laying {107} of eggs, or at least ovoviviparity,
would follow from the structure of the egg, since the abundance of yolk
would do away with the necessity for a placenta. That the eggs had this
Saurian characteristic was first definitely made known by Professor
Poulton[53] for _Ornithorhynchus_, and his results were confirmed later for
_Echidna_.[54] The structure of the eggs has, however, already been dealt
with on p. 72. The fact that these animals lay eggs appears to have been
known for a very long time, though rediscovered so lately as 1884 by Mr.
Caldwell.[55] In connexion with the structure of the ova, the ovaries
themselves and the oviducts are built upon the Sauropsidan plan. In the
male the testes retain the primitive abdominal position. The fact that the
urinary and genital products escape by means of their ducts into a chamber
which also receives the end of the alimentary tract is not a distinctive
feature of this group, inasmuch as it is seen in the Marsupials, and also
in certain low Eutheria, such as the Beaver and other Rodents, and a few
Insectivores. As to external features, the Monotremata show certain archaic
characters. The unspecialised arrangement of the mammary glands has already
been described. These animals are plantigrade, if the term may be used also
to describe the aquatic _Ornithorhynchus_. The ears are absolutely
destitute of a conch. The remarkable spur upon the hind-legs furnished with
a gland, which is more marked in the male, and indeed disappears in the
female of _Ornithorhynchus_, is a structure which argues the specialised
condition of these two modern representatives of what must have been a
large order in the past.

{108} [Illustration]

FIG. 51.--Ventral view of skull of _Echidna aculeata_, and right half of
mandible, _ang_, Angle of mandible; _aud.oss_, auditory ossicles; _cond_,
condyle of mandible; _cor_, coronoid process; _max_, maxilla; _oc.cond_,
occipital condyle; _pal_, palatine; _p.max_, premaxilla; _pt_, pterygoid;
_sq_, squamosal; _ty_, tympanic ring. (After Parker and Haswell.)

The skeleton shows numerous ancient characteristics. In the skull there is
no demarcation of the orbit from the temporal fossa, a feature widely found
in archaic mammals. The tympanic remains as a slender ring, there being no
auditory bulla formed either from this or from any other bone. The malleus
and incus are large, and thus reminiscent of the quadrate and articular
bone of reptiles. In the lower jaw the absence of a marked coronoid
process, and the absence of a firm ossification at the meeting of the two
rami, may be a primitive state of affairs. It must be remembered, however,
that the Cetacea show the same characters, though it is possible that they
too are developed from a low mammalian stock. In the vertebral column we
find the typical mammalian seven cervicals; but those characteristically
mammalian structures the epiphyses are totally absent in _Echidna_, and
only to be seen in the tail-region in _Ornithorhynchus_. In having only the
capitular head to the ribs, these mammals are evidently far removed from
all other mammals, and are even more reptilian than the Theromorphous
reptiles. The large clavicles and the interclavicle (Fig. 52, {109} p. 109)
are characteristic of the group, and the latter bone is peculiar to the
Monotremata among mammals. So, too, is the large coracoid. In the scapula
there is a spine which coincides with the anterior border of that bone. The
arrangement of the muscles in this region proves conclusively that this
projection is the homologue of the spine and the acromion of other mammals.
Here, again, we have a point of likeness to the Cetacea.[56] In the pelvis
the acetabulum is perforate (in _Echidna_), as in Sauropsida.

[Illustration]

FIG. 52.--Side view of right half of the shoulder girdle of a young Echidna
(_Echidna aculeata_). × 1. _a_, Acromion; _c_, coracoid; _cb_, coracoid
border; _cl_, clavicle; _css_, coraco-scapular suture; _ec_, epicoracoid;
_gb_, glenoid border; _gc_, glenoid cavity; _ic_, interclavicle; _pf_,
postscapular fossa; _ps_, presternum; _s_, spine; _ss_, suprascapular
epiphysis; _ssf_, subscapular fossa. (From Flower's _Osteology_.)

Considering the numerous very archaic features which the general structure
of this group displays, it is surprising to find how typically mammalian
they are in certain other peculiarities. The mammalian diaphragm, one of
the distinguishing features of the class, is perfectly normal in the
Monotremata. The alimentary canal shows no great divergences from the
normal structure. The stomach is almost globular, with a projecting pyloric
region in _Ornithorhynchus_; the intestine is divided into a "small" and
"large" intestine by a slender caecum. The liver has the subdivisions that
this organ usually shows in the Mammalia. However, the presence of the
ventral mesentery and of the abdominal vein in _Echidna_ and
_Ornithorhynchus_ has already been mentioned as a distinctive character.
The peculiar and apparently partly primitive valve of the right ventricle
has been described above (see p. 66). The brain is in most respects
mammalian in its characters, but naturally shows some important
differences. Dr. Elliot Smith, who has most recently studied this
question,[57] is of opinion that the size of the cerebral hemispheres is
not at all reptilian; indeed, it "greatly exceeds that of {110} many other
mammals." In _Echidna_, too, but not in _Ornithorhynchus_, the hemispheres
are well convoluted, though the arrangement of these convolutions cannot be
brought into line with what is known concerning the convolutions upon the
hemispheres of other mammals. It had been stated that in these animals, at
least in _Echidna_, there were only two optic lobes, as in lower
vertebrates, instead of the mammalian four. The late Sir W. H. Flower set
this matter at rest,[58] and showed that _Echidna_ was in this respect
typically mammalian. The absence of the corpus callosum is one of the
principal features separating the Monotremes from other mammals.

The Monotremata are represented to-day by two types, _Ornithorhynchus_ and
_Echidna_, which are no doubt worthy of being placed in separate families.
Fossil remains of the group (apart from the problematical Multituberculata)
are only known from Pleistocene times in Australia, and consist of the
bones of a large species of _Echidna_, and some fragments of
_Ornithorhynchus_, indicating a smaller animal than the living Platypus.

[Illustration]

FIG. 53.--Brain of _Echidna aculeata_, dorsal view. (Nat. size.) (From
Parker and Haswell's _Zoology_.)

FAM. 1. ECHIDNIDAE.--This family contains two genera, of which _Echidna_ is
the older and much the better known. The skin is abundantly covered with
spines, with which are mingled hairs. The snout is tapering, the tail
rudimentary, and the fingers and toes five in number. The spur and gland
upon the calcaneum are smaller than in _Ornithorhynchus_. The claws are
very strong, serving to tear open the ants' nests, upon the inhabitants of
which the Echidna feeds, licking them up with a long extensile tongue like
that of _Myrmecophaga_. In relation to this habit the salivary glands are
enormously developed, and indeed the animal has been confounded with
_Myrmecophaga_,[59] as the vernacular name "Australian Anteater"
exemplifies. {111}

In the skull the Echidna differs from _Ornithorhynchus_ in the greater
extension backwards of the palatines, and the larger size of the
pterygoids. The extent and relations of these bones to each other is not at
all unlike that which obtains in many Whales. The premaxillae show traces
of the same divergence followed by convergence of their ends that is seen
in the Platypus. There are only sixteen pairs of ribs, and either three or
four lumbar vertebrae. _Echidna_ has no trace of teeth, and there are no
horny pads which take their place; the mouth is as edentulous as in the
true American Anteaters. The brain (Fig. 53) is marked by sulci, contrary
to what we find in _Ornithorhynchus_. The genus has been divided into three
species, but it is doubtful whether more than one can be allowed, which
ranges from Australia through the Papuan region. While there is but one
species of true _Echidna_, a New Guinea species must clearly be referred to
a distinct genus _Proechidna_.[60] This animal is to be distinguished by
the fact that there are usually but three toes on each foot. But there are
copious rudiments of the other phalanges, upon which claws are sometimes
developed. The beak is curved downwards, and the back is rather arched; the
whole animal has the most singular likeness to an Elephant! The ribs are
increased by one pair, and there are four lumbar vertebrae. The one species
is named _P. bruijnii_. The Hon. W. Rothschild[61] distinguishes a form _P.
nigroaculeata_, which is allowed by Mr. Lydekker.

[Illustration]

FIG. 54.--Australian Anteater. _Echidna aculeata._ × 1/6.

{112}

The Echidna feeds like anteaters, by thrusting its tongue into an ant-hill,
and waiting until it is covered with indignant and marauding ants, which
are then swallowed. But this animal also devours worms and insects, which
are extracted from their hiding-places by the tongue. It is mainly
nocturnal, and prefers the seclusion of the densest scrubs of the bush, or
rocky spots where it is free from intrusion. Dr. Semon did not find that
the spur of this animal was used at all in self-defence; but he thinks that
possibly the weapon may be used, in the breeding season only, in the
combats of the males for the females, when perhaps, as has been shown to be
the case in _Ornithorhynchus_, the gland attached to it produces a
poisonous secretion.

The egg, as it appears, is transferred to the pouch by the mouth of the
mother; the shell is broken by the emerging young one, which has an
egg-breaking tubercle on its snout for this purpose; the mother removes the
shell. When the young has attained a certain size, the mother removes it
from the pouch, but takes it in from time to time to suckle it. When on her
nightly rambles the young one is left in a burrow dug for the purpose. Dr.
Semon was able, from his own observations, to substantiate this act of
intelligence on the part of the Echidna. It is well known that the
temperature of the Monotremes is less than that of higher mammals; in
addition to this fact Dr. Semon found that the range of variation of
temperature in the Echidna was as much as 13 degrees or more. It is thus
intermediate between the "poikilothermal" reptiles and the "homoeothermal"
mammals.

FAM. 2. ORNITHORHYNCHIDAE.--There is no need to attempt to define this
family, since it contains but one genus _Ornithorhynchus_, with but one
species, _O. anatinus_. The general aspect of the animal is well known. It
is covered with dense fur of a blackish brown colour; the limbs are short
and five-toed, the toes being webbed. The tail is longish and broad, being
flattened from above downwards. The webbing on the anterior toes
considerably outdistances the tips of the claws, as in the Seals. But this
is not the case with the hind-feet. The "beak," which is broad and flat,
and does actually suggest that of a duck, is not covered with horn, as is
often stated, but with a fine, soft, sensitive, naked skin, which abounds
in sense-organs of a tactile nature. As to characters derived from the
skeleton, _Ornithorhynchus_ has {113} seventeen pairs of ribs and only two
lumbar vertebrae. The skull is expanded in front, and the bill is supported
by two, at first diverging, and then converging, premaxillae. Between them
is the famous "dumb-bell shaped bone," which is believed to be the
representative of the reptilian prevomer. The pterygoids are smaller than
in _Echidna_, and the hard palate does not extend so far back as in that
genus. The brain of this genus is smooth.

[Illustration]

FIG. 55.--Duck-billed Platypus. _Ornithorhynchus anatinus._ × 1/6.

The discovery of the real teeth of _Ornithorhynchus_ only dates from the
year 1888, when they were found by Professor Poulton[62] in an embryo.
Later Mr. Thomas found[63] that the teeth persist for a considerable
portion of the animal's life, and are only shed, like milk teeth, "after
being worn down by friction with food and sand." We have already (p. 98)
called attention to the general similarity of these teeth to those of
certain of the earliest Mammalia and of mammal-like reptiles. The teeth are
all molars, and they are either eight or ten in number. They are replaced
by the horny plates of the adult animal; but the mode of replacement is
curious. The plates are developed from the epithelium of the mouth, but
round and under the true teeth; the epithelium of the mouth grows gradually
under the calcified teeth, a method of growth which has possibly something
to do with the shedding of the latter. The hollows and {114} grooves in the
plates are the remains of the original alveoli of the teeth.

[Illustration]

FIG. 56.--Skeleton of male _Ornithorhynchus_. Ventral view. The right
fore-limb has been separated and turned round so as to bring into view the
dorsal surface of the manus. The lower jaw is removed. _acc.tars_,
Accessory tarsal bone supporting the spur; _ant.pal.for_, anterior palatine
foramen; _ast_, astragalus; _atl_, atlas; _ax_, axis; _bs.oc_,
basi-occipital; _bs.sph_, basi-sphenoid; _calc_, calcaneum; _cbd_, cuboid;
_cerv.rb_, cervical rib; _clac_, clavicle; _cond.for_, foramen above inner
condyle of humerus; _cor_, coracoid; _cun_, cuneiform of carpus; _dent_,
horny dental plate; _ect.cun_, ecto-cuneiform; _ent.cun_, ento-cuneiform;
_ep.co_, epicoracoid; _epist_, episternum; _ep.pb_, epipubis; _fb_, fibula;
_fem_, femur; _for.mag_, foramen magnum; _glen_, glenoid cavity of
shoulder-joint; _glen_, glenoid cavity for mandible; _hum_, humerus;
_in.cond_, inner condyle of humerus; _inf.orb.for_, points to position of
infra-orbital foramen; _infr.proc_, inferior processes of caudal vertebrae;
_int.rbs_, intermediate ribs; _isch_, ischium; _mag_, magnum of carpus;
_max_, maxilla; _max.for_, maxillary foramen; _metat.I_, first metatarsal;
_metat.V_, fifth metatarsal; _nas.cart_, nasal cartilage; _obt_, obturator
foramen; _ol_, olecranon; _out.cond_, outer condyle of humerus; _pal_,
palatine; _pat_, patella; _post.pal.for_, posterior palatine foramen;
_pr.max_, premaxilla; _pr.st_, presternum; _pter_, pterygoid; _pub_, pubis;
_rad_, radius; _scap_, scapula; _scaph_, scaphoid of tarsus; _scaph.lun_,
scapho-lunar; _ses_, sesamoid bones of wrist and ankle; _sp_, tarsal horny
spur; _sq_, squamosal; _tib_, tibia; _trd_, trapezoid; _trm_, trapezium;
_tym.c_, tympanic cavity; _uln_, ulna; _unc_, unciform; _vom_, vomer; _x_,
dumb-bell shaped bone; _zyg_, zygomatic arch; _I-V_, digits of manus; _V_,
foramen for fifth nerve. (From Parker's _Zoology_.)

{115}

The Duck-billed Platypus is, as every one knows, an aquatic animal. It is
not found all over Australia, but is limited to the southern and eastern
parts of that continent, and to Tasmania. The animal excavates a burrow for
itself in the bank of the slow streams which it frequents. The burrow has
one opening below the water and one above; and it is of some length, twenty
to fifty feet. The Platypus feeds upon animal food, chiefly "grubs, worms,
snails, and, most of all, mussels." These it stows away when captured into
its capacious cheek-pouches. The food is then chewed and swallowed above
the surface as the animal drifts slowly along. Dr. Semon, from whose work,
_In the Australian Bush_, this account of the animal's habits is quoted,
thinks that in the nature of the food of the creature the explanation of
the loss of the teeth is to be found. He is of opinion that for cracking
the hard shells of the mollusc _Corbicula nepeanensis_, upon which
_Ornithorhynchus_ mainly feeds, the horny plates are preferable to brittle
teeth. _Ornithorhynchus_ is apparently not eaten by the natives by reason
of its ancient and fish-like smell. Besides, it is hard to catch on account
of its diving capacities, which are aided by an acute sense of sight and of
hearing. When the Duck-bill was first brought to this country it was
believed to be a deliberate fraud, analogous to the mermaids produced by
neatly stitching together the forepart of a monkey and the tail of a
salmon.

       *       *       *       *       *


{116}

CHAPTER VI

INTRODUCTION TO THE SUB-CLASS EUTHERIA

SUB-CLASS II.--_EUTHERIA_

DEFINITION.--Mammalia with teats. Mammary glands of sebaceous type. Heart
with entirely membranous and complete right auriculo-ventricular valve.
Brain generally with a corpus callosum. Coracoid much reduced and not
reaching sternum. No interclavicle. Vertebrae with epiphyses. Ribs
double-headed. Viviparous, with a small ovum.

In this group are included not only the Eutheria in the sense of Huxley,
but also his Metatheria. Though the Metatheria, or Marsupials as we shall
term them, undoubtedly form a most distinct order of mammals, perhaps even
a trifle more distinct than most others, their differences from the
remaining tribes are not by any means so great as those which separate
_Ornithorhynchus_ and _Echidna_ from all other mammals. In his well-known
memoir upon the arrangement of the Mammalia,[64] Professor Huxley
enumerated eleven characters as distinguishing the Metatheria either from
the Prototheria or from the Eutheria. Of these only three were characters
in which they approach the lower mammals. According to his showing,
therefore, the preponderance of marsupial features are Eutherian. The three
characters of Prototherian type are (1) the presence of epipubes; (2) the
small corpus callosum; (3) the absence of an allantoic placenta.

The last of these can be dismissed, in consequence of the recent discovery
of an allantoic placenta in _Perameles_. The first character is apparently
a valid distinction between the Marsupials {117} and their mammalian
relatives higher in the series; but it is not a character that should have
been made use of by Huxley, since he believed in the existence of a
corresponding element in the Dog. As to the corpus callosum (Fig. 50, p.
77) being small, that seems to be not more than a slight difference of
degree.[65] A number of other characters of secondary importance were added
by Huxley to the weight of evidence which led him to form a group
Metatheria for the Marsupials. Some of these, however, are now known to be
not evidence in that direction. For instance he observed that no Marsupial
had more than a single successional tooth. It seems at the present moment
to be fairly clear that Marsupials have a milk dentition like other
Eutherians, but that only one of these teeth, the fourth premolar, comes to
functional maturity. That it is really one of a complete milk series is
evidenced by the fact that this tooth is differentiated contemporaneously
with another series formerly held to belong to the so-called prelacteal
dentition.[66] There still remains, of course, the actual fact that the
milk dentition is not for the most part functional, but its significance
breaks down with these fresh discoveries. Of this Professor Osborn has
remarked: "The discovery of the complete double series seems to have
removed the last straw from the theory of the marsupial ancestry of the
Placentals." But Huxley did not lay much stress upon this matter of the
teeth, since he observed that similar suppressions of the milk dentition
were to be found in many other mammals admittedly Eutherian.

[Illustration]

FIG. 57.--Brain of _Echidna aculeata_; sagittal section. _ant.com_,
Anterior commissure; _cbl_, cerebellum; _c.mam_, corpus mammillare;
_col.forn_, column of the fornix; _c.qu_, corpora quadrigemina; _gang.hab_,
ganglion habenulare; _hip.com_, hippocampal commissure; _med_, medulla
oblongata; _mid.com_, middle commissure; _olf_, olfactory lobe; _opt_,
optic chiasma; _tub.olf_, tuberculum olfactorium; _vent. 3_, third
ventricle. (From Parker and Haswell's _Zoology_.)

Huxley regarded the peculiarities in the reproductive organs {118} of the
Marsupials as "singularly specialised characters," in no way intermediate
in character. This view applies also to the pouch, which, as already
stated, distinguishes the adults of that group. But the impossibility of
using this last character as one of any importance has been shown by the
discovery of rudiments of it in embryos of undoubtedly Eutherian mammals
(see p. 18).

[Illustration]

FIG. 58.--Sagittal section of brain of Rock Wallaby (_Petrogale
penicillata_). _ant.com_, Anterior commissure; _cbl_, cerebellum; _c.mam_,
corpus mammillare; _c.qu_, corpora quadrigemina; _crur_, crura cerebri;
_epi_, epiphysis, with the posterior commissure immediately behind it;
_f.mon_, position of foramen of Monro; _hip.com_, hippocampal commissure,
consisting here of two layers continuous behind at the spleneium, somewhat
divergent in front where the septum lucidum extends between them; _hypo_,
hypophysis; _med_, medulla oblongata; _mid.com_, middle commissure; _olf_,
olfactory lobe; _opt_, optic chiasma; _vent. 3_, third ventricle. (From
Parker and Haswell's _Zoology_.)

Less stress is laid now upon the existence of four molars in the Marsupials
as dividing them from the higher mammals than was formerly the case. The
total dentition of the group is on the whole composed of more numerous
individual teeth than in the typical Eutheria; but we have exceptions like
the Whales, the Armadillo _Priodontes_, and the Manatee; or better, because
free from the suspicion of secondary multiplication, _Otocyon_ and
occasionally (according to Mr. Thomas) _Centetes_. In the last two there
are at least sometimes four molars.

On the other hand, a few archaic characters of some importance crop up here
and there among the Marsupials, which are sometimes held to point to a
primitive ancestry. It has been remarked that in Marsupials it is the
fourth toe which is dominant in size, whereas in Ungulates it is the third.
An attempt has been made to explain this on the view (reasonable enough in
itself) of a tree-living ancestry for the group. A greater development of
the fourth toe is, however, by no means a necessary character of arboreal
creatures; the Primates themselves are an exception. Nor is this prevalence
universal among the Marsupials; {119} in _Myrmecobius_ (alone) is the third
toe the longest; and no great difference can be detected between the third
and fourth toes in the case of the genera _Phascologale_, _Didelphys_, and
some others. Professor Leche compares the predominance of the fourth toe
with the hyperphalangeal condition in the fourth toe of the embryo
Crocodile, and considers it an archaic feature, not surpassed by the
ancient characteristics of the Monotremata. Again it has been pointed out
that in _Phascologale_ and _Perameles_, the epistropheus (axis vertebra)
has a separate rib as in _Ornithorhynchus_. In the third place, the
likeness of the teeth of _Myrmecobius_ to those of _Ornithorhynchus_ is an
argument in the same direction, which is furthermore supported by the great
age (Mesozoic) of the Metatherian group, if we are right in regarding those
extinct creatures as Marsupials.

We may now mention certain facts which are not so generally used. The
partly primitive structure of the right auriculo-ventricular valve in the
Monotremata has no counterpart in any Marsupial which has been dissected;
but there are traces in the latter of the characteristic "ventral
mesentery" of _Ornithorhynchus_ and _Echidna_.[67] Mr. Caldwell's
interesting observation upon the segmenting egg of the Marsupial, the
incompleteness of the first segmentation furrow (reminding us of the
meroblastic ovum of the Monotreme), may possibly not turn out to be so
exclusively Marsupial a feature as has been thought.

The balance of evidence thus points to the nearer relationship of the
Marsupials to the Eutherian mammals; and their great specialisation
combined with certain evidences of degeneration (disappearance in part of
the milk dentition), and their age, point to the fact that they are, at any
rate, the descendants of an early form of Eutherian. But they must have
separated from the Eutherian stock after it had acquired a definite
diphyodonty and the allantoic placenta, the two principal features of the
Eutherian as opposed to the Prototherian mammals.

Nevertheless it seems probable that the Marsupial tribe is derived from
some of the earliest Eutherians. And on this view may be explained the
retention of Prototherian characters.

The remaining Eutheria are obviously all to be referred to one great
division with the possible exception of the Whales, whose affinities form
one of the principal difficulties to the student {120} of this group. A
short résumé of what is at present thought of the systematic position of
this anomalous order is appropriate here. Albrecht went so far as to regard
the Cetacea as the nearest group of animals to the hypothetical
Promammalia.[68] But discounting his arguments by the removal of such of
them as relate to structure plainly altered by the singular mode of life of
these creatures, there is really a great deal to be said in favour of his
view.

The chief facts which argue a primitive position among mammals for the
Cetacea are perhaps: (1) the slight union of the rami of the lower jaw; (2)
the occasionally rather marked traces of the double constitution of the
sternum; (3) the long and simple lungs; (4) the retention of the testes
within the body-cavity; (5) the occasional presence (in _Balaenoptera_) of
a separate supra-angular bone. These points, however, are but few, and are
not of such great weight as those which ought to be present to establish a
claim to separate treatment for the Cetacea as opposed to the Eutheria. If
this group of mammals can be tacked on anywhere, it appears to us that the
nearest relatives are not, as is sometimes put forward, the Ungulata or the
Carnivora, but the Edentata. There are quite a number of rather striking
features in which a likeness is shown between these apparently diverse
orders of mammals. The chief ones are these: (1) the existence of traces of
a hard exoskeleton, of which vestiges remain in the Porpoise; (2) the
double articulation of the rib of the Balaenopterids to the sternum, with
which compare the conditions obtaining in the Great Anteater; (3) the
concrescence of some of the cervical vertebrae; (4) the share which the
pterygoids may take in the formation of the hard palate; (5) the fact that
in the Porpoise, at any rate, as in many Edentates, the vena cava, instead
of increasing in size as it approaches the liver, diminishes.

Another group which is perfectly isolated is that of the Sirenia. The
alliance advocated by some with the Cetacea, and quite recently renewed by
Professor Haeckel, is contradicted by so many important features that it
seems necessary to abandon it. The recent discovery of a fossil Sirenian
jaw by Dr. Lydekker with teeth highly suggestive of those of Artiodactyla,
may prove a clue. A third group which is so isolated as to have been placed
in a {121} primary division, proposed to be called Paratheria, is that of
the Edentates. Probably the group so called should really be divided into
the Edentata and the Effodientia, the latter containing the Old World
forms. Whether or not it be ultimately shown that the Ganodonta are
ancestral Edentates (_sensu strictiori_), the connexion of the group with
others is not at present plain. The same is the case with the extensive
order of Rodents. It is true that the extinct order of the Tillodontia
shows certain Rodent-like characters on the one hand, and likenesses to
Ungulates on the other. Certain likenesses shown by such apparently diverse
animals as the Rabbit and the Elephant used to be insisted upon by
Professor Huxley. For the present, however, the Rodents must remain as an
isolated group with only very dubious affinities to others. The remaining
groups of existing mammals are easier to connect. At first the differences
between a Cat and a Horse seem to be quite as wide as those which separate
any two of the higher Eutherian orders. But it seems to become clearer and
clearer, as palaeontological investigation proceeds, that the bulk of the
Ungulate and the Carnivorous, Insectivorous, and perhaps Lemuroid stocks
converge into the early Eocene Creodonta. From the Lemuroid branch the
higher Primates can be derived. The only "Ungulates" which cannot be fitted
in with some reasonable probability is the group of the Proboscidea. But of
the early forms of this division we have at present no knowledge.

       *       *       *       *       *


{122}

CHAPTER VII

EUTHERIA--MARSUPIALIA

ORDER I. MARSUPIALIA[69]

The Marsupials may be thus defined:--Terrestrial, arboreal, or burrowing
(rarely aquatic) mammals, with furry integuments; palate generally somewhat
imperfectly ossified; jugal bone reaching as far as the glenoid cavity;
angle of lower jaw nearly always inflected. The clavicle is developed.
Arising from the pubes are well developed and ossified epipubic bones.
Fourth toe usually the most pronounced. Teeth often exceed the typical
Eutherian number of forty-four; molars generally four on each side of each
jaw. As a rule but one tooth of the milk set is functional, which is
(according to many) the fourth premolar. Teats lying within a pouch, in
which the young are placed. Young born in an imperfect condition, and
showing certain larval characters. There is a shallow cloaca. The testes
are extra-abdominal, but hang in front of the penis. In the brain the
cerebellum is completely exposed; the hemispheres are furrowed, but the
corpus callosum is rudimentary. An allantoic placenta is rarely present.

Structurally the Marsupials are somewhat intermediate between the
Prototheria and the more typical Eutheria, with a greater resemblance to
the latter.

[Illustration]

FIG. 59.--Rock Wallaby (_Petrogale xanthopus_), with young in pouch. × 1/7.
(After Vogt and Specht.)

The name Marsupial indicates what is perhaps the most salient character of
this order. The pouch in which the young are carried is almost universally
present. It is less developed {123} on the whole in the Polyprotodont
forms, such as the Thylacine, Dasyures, etc., but is found in so many of
them that the two divisions of the Marsupials, the Diprotodonts and the
Polyprotodonts, cannot be raised to distinct orders on this and other
grounds. The marsupial pouch of the Marsupials must not, as has been
already pointed out, be confounded with the pouch of the Monotreme mammals.
Distinct teats are found in the marsupium of the Marsupials, while there
are none in the mammary pouch of the Monotreme, the pouch itself indeed
representing an undifferentiated teat, of which the walls have not closed
up. The pouch opens forward in the Kangaroos, and backwards in the
Phalangers and in the Polyprotodonts. Its walls are supported by a pair of
bones diverging from each other in a [70]-shaped manner; these are
cartilaginous and vestigial in the Thylacine. They {124} are the precise
equivalents of similar bones in the Monotremata. It has been held, but
apparently erroneously, that these bones are mere ossifications in the
tendons of the external oblique muscle of the abdomen, or of the
pyramidalis of the same region; and vestiges have been asserted to exist in
the Dog. Such bonelets are undoubtedly present in the Dog; but it seems
clear from their development in Marsupials, as structures actually
continuous with the median unossified portion of the symphysis pubis, that
the "marsupial bones" belong to that part of the skeleton, and that they
correspond with the epipubis of certain amphibians and reptiles. The pouch,
it may be remarked, exists in a rudimentary form in the males of many
Marsupials.

[Illustration]

FIG. 60.--Ventral surface of innominate bone of Kangaroo (_Macropus
major_). × 1/3. _a_, Acetabulum; _ab_, acetabular border of ilium; _is_,
iliac surface; _m_, "marsupial" bone; _pb_, pubic border; _pt_, pectineal
tubercle; _s_, symphysis; _si_, supra-iliac border; _ss_, sacral surface;
_thf_, thyroid foramen; _ti_, tuberosity of ischium. (From Flower's
_Osteology_.)

[Illustration]

FIG. 61.--Mammary foetus of Kangaroo attached to the teat. (Nat. size.)
(From Parker and Haswell's _Zoology_.)

The most salient feature in the life-history of the Marsupials is the
imperfect condition in which the young are born. The egg is no longer laid,
as in the Monotremes; but curiously enough the ovum, which has the small
size of that of the Eutheria, divides incompletely at the first division
(as Mr. Caldwell has shown), and this developmental feature may perhaps be
looked upon as a reminiscence of a former large-yolked condition. The young
when born are small and nude; the newly born young of a large Kangaroo is
perhaps as large as the little finger. The young are transferred by the
lips of the mother to the pouch, where they are placed upon a teat. It is
an interesting fact that they are not merely imperfect foetuses, but that
they are actual larvae. They possess in fact at any rate one larval organ
in the shape of {125} a special sucking mouth. This sucking mouth is an
extra-uterine production, and is of course an adaptation to the particular
needs of the young, just as are other larval organs, such as the
chin-suckers of the tadpole, or the regular ciliated bands of the larvae of
various marine invertebrate organisms.

There are a number of other features which distinguish the Marsupials from
other mammals.

The cloaca of the Marsupials is somewhat reduced, but is still
recognisable. Its margins in _Tarsipes_ are even raised into a wall, which
projects from the body.

The tooth series of the Marsupials was once held to consist of one
dentition only, with the exception of the last premolar, which has a
forerunner. The interpretation of the teeth of Marsupials are various.
Perhaps most authorities regard the teeth as being of the milk dentition,
with the exception of course of the single tooth that has an obvious
forerunner. But there are some who hold that the teeth are of the permanent
dentition. In any case it is proved that a set of rudimentary teeth are
developed before those which persist. Those who believe in the persisting
milk dentition describe these as prelacteal. Another matter of importance
about the teeth of this order of mammals is that their numbers are
sometimes in excess of the typical Eutherian 44. This, however, holds good
of the Polyprotodonts only.

It was for a long time held that the Marsupials differed from all other
mammals in having no allantoic placenta. But quite recently this supposed
difference has been proved to be not universal by the discovery in
_Perameles_ of a true allantoic placenta. The Marsupials have been
sometimes called the Didelphia. This is on account of the fact that the
uterus and the vagina are double. Very frequently the two uteri fuse above,
and from the point of junction an unpaired descending passage is formed
(see Fig. 48 on p. 74).

A character of the brain of Marsupials has been the subject of some
controversy. Sir Richard Owen stated many years ago that they were to be
distinguished from the higher mammals by the absence of the corpus
callosum. Later still it was urged that a true corpus callosum, though a
small one, was present; while, finally, Professor Symington[71] seems to
have shown that {126} the original statement of Owen was correct, at least
in part. It is at most feebly developed (see Fig. 58, p. 118).

As to skeletal characters, the Marsupial skull has on the whole a tendency
towards a permanent separation of bones usually firmly ankylosed. Thus the
orbitosphenoids remain distinct from the presphenoid. The palate is largely
fenestrated, a return as it were--says Professor Parker--to the
Schizognathous palate of the bird. The mandible is inflected; this familiar
character of the Marsupials goes back to the earliest representatives of
the order in Mesozoic times (see p. 96); but it is not absolutely
universal, being absent from the much weakened skull of _Tarsipes_. On the
other hand, the inflection is nearly as great in certain Insectivores, in
_Otocyon_, etc. The malar always extends back to form part of the glenoid
cavity. The shoulder girdle has lost the large coracoid of Monotremes; this
bone has the vestigial character that it possesses in other Eutheria. The
clavicle is present except in the Peramelidae. A third trochanter upon the
femur seems to be never present.

[Illustration]

FIG. 62.--Skull of Rock Wallaby (_Petrogale penicillata_). (Ventral view.)
_ali_, Alisphenoid; _bas.oc_, basi-occipital; _bas.sph_, basi-sphenoid;
_ex.oc_, ex-occipital; _ju_, jugal; _max_, maxilla; _pal_, palatine;
_par.oc_, paroccipital; _p.max_, premaxilla; _pr.sph_, presphenoid; _pt_,
pterygoid; _sq_, squamosal; _ty_, tympanic. (From Parker and Haswell's
_Zoology_.)

The Marsupials cannot be regarded as an intermediate stage in the origin of
the Eutheria for a number of reasons. In the first place, the nature of
their teeth shows them to be degenerate animals; one set, whether we regard
it as the milk or permanent dentition, has become vestigial. The recent
discovery of a true allantoic placenta in _Perameles_ removes one reason
for regarding {127} the Marsupials as primitive creatures. It implies on
the whole that the Marsupials have sprung from a stock with an allantoic
placenta. The alternative is to assume the independent development of an
allantoic placenta in both groups of the Mammalia; unless indeed the genus
_Perameles_ is to be held to be the most primitive race of Marsupials
living, a hypothesis which does not appear on the face of it likely. So
long as it was believed that the mammary pouch of the Monotremes was the
equivalent of the marsupium of the Marsupials, the persistence of this
structure seemed to be a bond of union between the groups. But it is now
known that the marsupium is a special organ confined to the Marsupials, an
argument which is rather in favour of their being a lateral development of
the mammalian stem. It is to be remarked also that the marsupium is
feeblest in the Polyprotodonts, which may perhaps be looked upon as the
most primitive of the Marsupials, owing to their more numerous teeth and
other points to be referred to immediately.

Not only are the Marsupials interesting from the point of view of their
structure; their present and past distribution is of equal interest. During
the Mesozoic epoch they occurred in Europe and North America; but not, so
far as negative evidence means anything, in Australia, which is now their
headquarters. In Europe Marsupials lingered on into the Tertiary period,
when they finally became extinct. In America, of course, the group has
persisted to the present day. Now it is important to notice that the two
main subdivisions of the Marsupials, the Polyprotodontia and the
Diprotodontia, exist to-day in both Australia and South America. These two
divisions, it should be explained, differ principally in that one has
numerous, the other rarely more than two,[72] incisors in the lower jaw. It
is perhaps the more widely distributed opinion that the Polyprotodontia are
the more archaic group; this opinion rests upon one or two facts in
addition to the absence of specialisation in the incisor teeth. Among the
Polyprotodontia the total number of teeth is greater--a clearly primitive
character; secondly, the general form of the body of these animals, with
four subequal limbs and carnivorous or omnivorous diet, contrasts with the
purely vegetarian and much specialised Kangaroos at any rate. Finally--and
sufficient stress {128} has perhaps not been laid upon this matter--the
brain among the Polyprotodonts is less convoluted than among the genera of
the other division. This statement is of course made with due regard to
parallelism in size (see p. 77). It is well known that the complexity of a
brain bears a distinct relation to the size of its possessor within the
group. Now the most ancient Marsupials are decidedly more
Polyprotodont-like. No European form from the earlier periods is distinctly
to be referred to the Diprotodonts. But both divisions now exist in America
and Australia.

We must assume, therefore, one of three hypotheses. Either the
differentiation into the two great divisions occurred in Jurassic or
Cretaceous times before the migration of the order southwards; or the
Diprotodont type is only a type, and not a natural group, _i.e._ it has
been separately evolved in America and Australia; or, finally, there was
formerly a land-connexion in the Antarctic hemisphere, along which the
Diprotodonts of Australia wandered into South America. The middle
hypothesis has this to commend it, that syndactylism occurs in both
divisions, and that in some Diprotodonts the pouch opens backwards as it
does in the Polyprotodonts. So great are the resemblances that but little
difference is really left--of great importance that is to say. Hence it is
not difficult to imagine the reduction of the incisors having taken place
twice. In favour of the first hypothesis there are no positive facts.
Finally, in favour of the last, which is so strongly supported by the facts
of distribution derived from the study of other groups of animals,[73]
there is at least this striking fact or rather series of facts: that some
of the South American fossil Polyprotodonts have a "strictly Dasyurine
relationship."[74] If there has not been a direct migration, then the
Dasyurine type has been twice evolved, an improbability that few will
attempt to explain away. In any case we shall adopt here the usual division
of the Marsupials into Diprotodontia and Polyprotodontia.

SUB-ORDER 1. DIPROTODONTIA.

This group includes the herbivorous Marsupials. The incisors are as a rule
three above, but one only in the Wombats. Below {129} is one strong pair,
with occasionally one or two rudimentary incisors. The upper canines, if
present, are not large. The molars are tuberculate or ridged. All
Marsupials (except the Wombats) to some extent, and the Macropods
especially, are characterised by the prolongation of the tubes of the
dentine into the clear enamel. The significance of this fact is, however,
lessened by the fact that the same penetration of the enamel by dentinal
tubes occurs in the Jerboa, the Hyrax, and some Shrews. The feet have two
syndactylous toes,[75] less marked in the Wombats than in the Kangaroos and
Phalangers.

[Illustration]

FIG. 63.--Skull of Wombat (_Phascolomys wombat_). (Lateral view.) _ang_,
Angular process; _cond_, condyle of mandible; _ext.aud_, opening of bony
auditory meatus; _ex.oc_, exoccipital; _ju_, jugal; _lcr_, lachrymal;
_max_, maxilla; _nas_, nasal; _p.max_, premaxilla; _sq_, squamosal; _ty_,
tympanic. (From Parker and Haswell's _Zoology_.)

This order is mainly Australian at the present day, using the term of
course in the "regional" sense (see p. 84); the only exception indeed to
this statement is the occurrence of the genus _Caenolestes_ in South
America. But it is now known that Diprotodont Marsupials formerly existed
in the same part of the world.

[Illustration]

FIG. 64.--Bones of right foot of Kangaroo (_Macropus bennetti_). _a_,
Astragalus; _c_, calcaneum; _cb_, cuboid; _e_^3, ento-cuneiform; _n_,
navicular; _II-V_, second to fifth toes. (From Flower's _Osteology_.)

{130}

[Illustration]

FIG. 65.--Skeleton of Wallaby (_Macropus ualabatus_). The scapula is raised
somewhat higher than in nature. The end of the tail is omitted. The head of
the femur has been separated from the acetabulum. _acet_, Acetabulum;
_acr_, acromion process; _ast_, astragalus; _cal_, calcaneum; _cbd_,
cuboid; _chev_, chevron-bones; _cl_, clavicle; _cun_, cuneiform of carpus;
_epi_, epipubis; _fb_, fibula; _fem_, femur; _hd_, head of femur; _hu_,
humerus; _il_, ilium; _isch_, ischium; _obt_, obturator-foramen; _orb_,
orbit; _pis_, pisiform; _pub_, pubis; _rad_, radius; _rb_^1, first rib;
_rb_^{13}, last rib; _sc_, scapula; _st_, sternum; _tb_, tibia; _troch_,
great trochanter of femur; _uln_, ulna; _unc_, unciform; _IV_, fourth toe.
(From Parker and Haswell's _Zoology_.)

FAM. 1. MACROPODIDAE.--This family contains the Kangaroos, Wallabies,
Rat-Kangaroos, and Tree-Kangaroos. With the exception of _Dendrolagus_ the
family is terrestrial, and its numerous species progress by leaps effected
by the long hind-limbs, which are decidedly, often greatly, longer than the
fore-limbs. In the hind-limb the fourth toe is very long and strong; the
fifth moderately so; the second and third are slender and united by skin.
The tail is always long, but differs in its characters from {131} genus to
genus. The stomach is much sacculated. The dental formula is I 3/1 C (1 or
0)/0 P 2/2 M 4/4. The atlas is often open below, forming thus an incomplete
ring.

Though the number of the incisor teeth in the adult Diprotodonts is never
more than three on each side in each jaw, more numerous rudiments are
present. Mr. M. Woodward[76] has lately investigated the subject with
interesting results. He finds that many species present decided traces of
two additional incisors, raising the total to that which characterises the
Polyprotodontia; but in two cases, viz. _Macropus giganteus_ and _Petrogale
penicillata_, a sixth is present, the total number being thus in excess of
that found in any other Marsupial. This, as the author himself admits,
proves too much. No mammal is known which in the adult condition has so
many incisors; nor do the fossil Mammalia help us to get over the
difficulty; even among reptiles it is not usual for so many teeth to occur
upon the premaxillaries.

It is a curious fact that the two long lower incisors can be used after the
fashion of a pair of scissors, or rather a pair of shears. Their inner
edges are sharpened, and they are capable of some motion towards and away
from each other; by their means grass is cropped.

The stomach of _Macropus_ (and of other allied genera) is peculiar by
reason of its long and sacculated character; the oesophagus enters it very
near the cardiac end, which is bifid. Messrs. Schäfer and Williams[77] have
shown that the squamous, non-glandular epithelium of the oesophagus extends
over the greater part of the stomach, only the pyloric extremity and one of
the two cardiac caeca being lined with columnar epithelium.

The Macropodidae are clearly divisible into three sub-families, which are
distinguished by marked anatomical characters.

In the sub-family MACROPODINAE (including the genera _Macropus_,
_Petrogale_, _Lagorchestes_, _Dorcopsis_, _Dendrolagus_, _Onychogale_, and
_Lagostrophus_) there is no hallux, and the tail is hairy. The oesophagus
enters the stomach near the cardiac end. The caecum when short has no
longitudinal bands; the liver has a Spigelian lobe.

The second sub-family, POTOROINAE or HYPSIPRYMNINAE (including the genera
_Potorous_, _Aepyprymnus_, _Bettongia_, and {132} _Caloprymnus_), consists
of smaller animals than the Macropodinae, which, however, resemble them in
having no hallux, but a hairy tail. The oesophagus enters the stomach near
the pyloric end of that organ. The caecum, though short, has lateral
longitudinal bands. The liver has no special Spigelian lobe. The canines
are always present, being rarely so in Macropodinae, and are usually well
developed.

The third sub-family, that of the HYPSIPRYMNODONTIDAE, is doubtfully
referable to the family; it consists of but one genus _Hypsiprymnodon_,
which is in many points more like a Phalanger than a Kangaroo. It has an
opposable hallux and a non-hairy, but scaly, tail. It has canines in the
upper jaw.

[Illustration]

FIG. 66.--Red Kangaroo. _Macropus rufus._ × 1/18.

SUB-FAM. 1. MACROPODINAE.--The genus _Macropus_ includes not only the
Kangaroos but also the Wallabies, which are really indistinguishable,
though they have sometimes been placed in a separate genus _Halmaturus_.
The genus thus enlarged contains twenty-three species. It may be thus
characterised: the ears are long, the rhinarium is usually naked, but in
_M. giganteus_ and others a band of hairs descends to the upper lip; a
naked band extends from the ankle to the pads on the digits, which is
interrupted in _M. rufus_ by a band of hairs just in front of the digits.
The mammae are four. The tail is not bushy, {133} but is crested in _M.
irma_. They are for the most part found on the Australian continent, but
some species are found in the islands to the north which belong to the
Australian region. Thus _M. brunii_, which is of interest as the first
Kangaroo seen by a European, is a native of the Aru islands. A specimen of
this animal, which was then living in the garden of the Dutch governor of
Batavia, was described by Bruyn in the year 1711. _M. rufus_, the largest
member of the group, is remarkable for the red secretion which adorns the
neck of the male. It is caused by particles which have the appearance and
colour of carmine. _M. giganteus_ is not, as its specific name might imply,
the "giant" of the race; its dimensions are given as 5 feet, while _M.
rufus_ is said to attain a length of 5 feet 5 inches, exclusive (in both
cases) of the tail.

The account which Sir Joseph Banks gives[78] in his diary of the Kangaroo
is interesting, since he was one of the first naturalists to see that
creature. In July 1770 it was reported to him that an "animal as large as a
greyhound, of a mouse colour, and very swift" had been seen by his people.
A little later he was surprised to observe that the animal "went only upon
two legs, making vast bounds just as the jerboa does." The second
lieutenant killed one of these Kangaroos, of which Sir Joseph Banks wrote
that "to compare it to any European animal would be impossible, as it has
not the least resemblance to any one I have seen. Its fore-limbs are
extremely short and of no use to it in walking; its hind, again, as
disproportionately long; with these it hops seven or eight feet at a time,
in the same manner as the jerboa, to which animal indeed it bears much
resemblance, except in size, this being in weight 38 lbs., and the jerboa
no larger than a common rat." The beast was killed and eaten, and proved
excellent meat. Sir Joseph Banks' observations upon the leaping of the
Kangaroo are of interest, because it is often asserted that the tail is
largely made use of as a third foot or as a support. Mr. Aflalo declares in
the most positive way that after repeatedly examining the tracks upon soft
sand immediately after the animal had passed, not the very faintest trace
of the impression of the tail could be discovered. The leaps of a big
Kangaroo seem to be somewhat greater than is recorded {134} by Banks. It is
said that 15 or even 20 feet are covered at a bound, and in bound after
bound. But in walking slowly it can be readily seen from an inspection of
Kangaroos at the Zoological Society's Gardens that the animal does rest
upon its tail, which with the hind-legs forms a tripod.

_Petrogale_ with six species comes next to _Macropus_, and is indeed only
to be differentiated from it by the thickly-haired and more slender tail,
which is not used, as it is sometimes in the Kangaroos, as an extra
hind-limb. The Rock-Kangaroos live among rocks, which they climb, and from
which they leap; and the tail acts rather as a balancing pole. The most
elaborate account of the anatomy of _Petrogale_ known to me is by Mr.
Parsons.[79] The dentition as given by Mr. Thomas is I 3/1 C 0/0 Pm 2/2
M 4/4--that of _Macropus_ without the occasionally occurring canine of the
upper jaw. The osteological characters which separate it from _Macropus_
are quite insignificant. Mr. Parsons mentions a wormian bone, "os
epilepticum," at the junction of the coronal and sagittal sutures. It was
found to occur in two out of five skulls examined, and appears not to occur
in other Kangaroos. The palatine foramina of _Petrogale_ are so large that
the posterior part of the bone is only a narrow thickened ridge. The small
intestine of _P. xanthopus_ is 102 inches long, the large intestine 44
inches. The caecum has a length of 6 inches, and is not sacculated,
differing in this from the caecum of _Macropus major_. The best known
species are _P. xanthopus_ and _P. penicillata_. The genus is confined to
Australia itself, and does not enter Tasmania.

_Onychogale_ includes the so-called "Nail-tailed Wallabies," which have a
thorn at the end of the tail, reminding one of the Lion and the Leopard,
whose tails have a similar armature. The muffle is hairy. Three species are
allowed by Mr. Thomas.

_Lagorchestes_ has, like the last genus, the rhinarium, _i.e._ that part of
the nose immediately surrounding the nostrils, hairy instead of smooth as
in the Kangaroos proper. It is distinguished from _Onychogale_ by the
absence of the terminal callosity to the tail, which is rather short. The
name Hare-Kangaroo is given to the members of this genus (three species) on
account of their exceeding fleetness. This genus is limited to Australia
itself. _L. conspicillatus_ is said to present "a remarkable {135}
resemblance to the English hare," and _L. leporoides_ was so called by
Gould on account of general appearance as well as face.

_Dorcopsis_ has shorter hind-legs than _Macropus_, and a naked muffle. The
ears are small. The structure of _D. luctuosa_ has been studied by
Garrod,[80] who pointed out the existence of four enlarged hair follicles
on the neck near the mandibular symphysis. These are, however, represented
in the next genus _Dendrolagus_, and occur also in _Petrogale_. The limbs
are not so disproportionate as in _Macropus_, and the tail is naked at the
tip.

_Dorcopsis_ and the next genus to be described, _Dendrolagus_, differ from
_Macropus_ and its immediate allies, _Petrogale_ and _Lagorchestes_, in a
number of anatomical points. In the first place, the premolars are twice
the size of those of _Macropus_, and they have a characteristic pattern not
observable in the Kangaroos. This consists of a median ridge (the whole
tooth being rather prismatic in shape), with lateral ridges at right angles
to it. The upper canines are developed, but are minute.

The stomach is not quite like that of _Macropus_, though built upon a
similar plan. The blind cardiac extremity is a single, not a double
cul-de-sac; in this it is like that of _Petrogale_. The distribution of the
squamous, white, oesophageal epithelium is very much like that of
_Dendrolagus_. In both genera the orifice of the oesophagus into the
stomach is guarded by two strong longitudinal folds, which run for some
distance towards the pylorus. In _Dendrolagus_, at any rate, this tract is
bordered on each side by glandular patches. In _Dendrolagus_, moreover, the
squamous epithelium does not extend into the cardiac cul-de-sac. This
latter is separated from the rest of the stomach by two slightly diverging
folds, which are faintly represented in _Petrogale_ and in _Halmaturus_. In
the last two genera the folds surrounding the oesophageal orifice are but
slightly represented; better in _Halmaturus_ than in _Petrogale_. But there
are not the patches of glands already referred to. The small intestine of
_Dorcopsis_ is 97 inches in length, the large being 32, _i.e._
proportionately long, as in Marsupials generally. The small caecum (2½
inches) is not sacculated.

The spleen is Macropodine, being [81]-shaped or [82]-shaped. The
differences between _Dorcopsis_ and the evidently closely allied
_Dendrolagus_ will be further considered under the description of {136} the
latter. _Dorcopsis_ is confined to New Guinea, and contains three species,
viz. _D. muelleri_, _D. luctuosa_, and _D. macleani_. _D. muelleri_ has a
striking resemblance to _Macropus brunii_, with which it has been
confounded. Though intermediate between _Macropus_ and _Dendrolagus_, these
Kangaroos are not arboreal.

The genus _Dendrolagus_ is remarkable for its un-kangaroo-like habit of
living in trees. In accordance with this change of habit is a relative
shortening of the hind-limbs, a feature which begins to be observable in
_Dorcopsis_. "The general build," writes Mr. Thomas, "is of the ordinary
mammalian proportions, not macropodiform at all." The muffle is not naked
for the greater part, though the shortness of the hairs gives that effect.
As in _Dorcopsis_, but not as in _Macropus_, the bulla tympani is not
swollen. There are altogether five species, the fifth, _D. bennetti_,
having been lately described from specimens living in the Zoological
Society's Gardens.

[Illustration]

FIG. 67.--Tree-Kangaroo. _Dendrolagus bennetti._ × 1/12.

The anatomy of this genus has been described by Owen for _D. inustus_,[83]
and by myself for _D. bennetti_. The stomach, which {137} has a single, not
bifid, cul-de-sac, is sacculated by two principal bands and other
subsidiary ones. Its internal structure has already been to some extent
described. The spleen of _D. bennetti_ is remarkable for the fact that it
is not [84]-shaped, whereas _D. inustus_ agrees with other Macropodines in
the form of this organ. The small intestine of _D. bennetti_ is 95 inches
long, the large 38. The caecum appears to differ in the two species; it is
smaller in _D. bennetti_, where it is only 2 inches in length. The most
remarkable feature of the liver is the large size of the left lateral lobe
and the bilobed condition of the Spigelian lobe; this at least was the case
with _D. bennetti_. A recently-described species[85] has been attentively
studied in its native haunts by Dr. Lumholtz.[86] It lives in the highest
parts of the mountainous scrubs of Queensland, where it moves quickly on
the ground as well as among the trees. It is hunted with Dingos by the
"blacks," and is eaten by them.[87]

_Lagostrophus_ is a generic name that has been proposed by Mr. Thomas for a
small Wallaby 18 inches in length, which is distinguished by the fact that
the long claws of the hind-limbs are entirely hidden by long and bristly
hairs; the muffle is naked; there is no canine. The bullae are swollen.
There is but one species of the genus, _L. fasciatus_, a native of West
Australia.

SUB-FAM. 2. POTOROINAE.--_Aepyprymnus_ and the other genera placed in this
sub-family are known by the vernacular name of Rat-Kangaroos, or sometimes
Kangaroo-Rats. The latter term has been called "incorrect," though it is
just as good as the former, both of them in fact being inaccurate as
implying some likeness to or relation with a Rat. The present genus has a
partially hairy rhinarium; the auditory bullae are not swollen. It contains
but one species, _Ae. rufescens_, a native of Eastern Australia, which is
distinguished by its very long hind-feet.

_Bettongia_ has long hind-feet as in _Aepyprymnus_, but the rhinarium is
entirely naked instead of being partially hairy, while the ears are much
shorter. The genus, which contains four species, is remarkable as being the
only ground-living mammal with a prehensile tail, which it uses to carry
grass, etc. {138} _B. lesueuri_ burrows in the ground, often to so great a
depth as 10 feet. The genus occurs in Tasmania as well as in Australia.

_Caloprymnus_, with one species, is a genus instituted by Mr. Thomas in his
Catalogue of Marsupials for a form (_C. campestris_) which combines in a
remarkable way the characters of _Aepyprymnus_, _Bettongia_, and
_Potorous_. The external characters and the general shape of the skull are
as in _Bettongia_, while the molars have the structure of those of
_Aepyprymnus_. The last premolar is as in _Potorous_.

Of the genus _Potorous_ there are three species, which are Tasmanian as
well as Australian. Unlike the other Rat-Kangaroos, the hind-feet are
comparatively short, and the animal is therefore less addicted to jumping
than its relatives. The rhinarium is naked, and the ears are of fair
length.

SUB-FAM. 3. HYPSIPRYMNODONTINAE.--The Musk-Kangaroo, _Hypsiprymnodon_, is
the last genus of the present family, and the only genus of this
sub-family. It is intermediate between the Macropodidae and the
Phalangeridae, the annectant character being mainly the hind-feet, which
though they have the same long fourth digit as the Kangaroos, have it more
feebly developed, and possess also an opposable hallux, which is one of the
salient features in the structure of the Phalangeridae. The tail is naked
and scaly; the rhinarium is entirely naked. The ears are large and not
furry. The single species, _H. moschatus_, appears to feed upon insects as
well as vegetables.

"Its habits are chiefly diurnal, and its actions when not disturbed by no
means ungraceful. It progresses in much the same manner as the
Kangaroo-Rats (_Potorous_), to which it is closely allied, but procures its
food by turning over the débris in the scrubs in search of insects, worms,
and tuberous roots, frequently eating the palm berries, which it holds in
its fore-paws after the manner of the Phalangers, sitting up on its
haunches, or sometimes digging like the bandicoots." This is Mr. Ramsay's
description of the animal, which he was the first to discover.[88]

FAM. 2. PHALANGERIDAE.--The genus _Hypsiprymnodon_ bridges over the not
very wide gap which separates the Kangaroos from the Phalangers. The
Phalangers are Marsupials with five fingers and toes; the second and third
toes are bound together by a {139} common integument as in the
Macropodidae. The hallux is opposable and nailless. The tail is nearly
always long and prehensile. The pouch is well developed; the stomach not
sacculated; a caecum is present (except in _Tarsipes_). These are really
the principal distinctions between the two families. In addition, it may be
mentioned that the lower incisors have not a scissor-like action as in the
Kangaroos.

The Phalangers may be divided into four sub-families.

The first of these, that of the PHALANGERINAE, contains the genera
_Phalanger_ (including _Cuscus_), _Acrobates_, _Distaechurus_, _Dromicia_,
_Gymnobelideus_, _Petaurus_, _Petauroides_, _Dactylopsila_, _Pseudochirus_,
and _Trichosurus_.

These genera agree in the following generalities:--Tail well developed,
often very long; three incisors above, and at least two premolars both
above and below; caecum long and simple; stomach without a cardiac gland;
liver not very complicated by secondary furrows, with a distinct caudate
lobe; the vaginal median culs-de-sac often coalesced; lungs with an azygos
lobe.

[Illustration]

FIG. 68.--Bones of leg and foot of Phalanger. _ast_, Astragalus; _calc_,
calcaneum; _cub_, cuboid; _ect.cun_, ecto-cuneiform; _ent.cun_,
ento-cuneiform; _fb_, fibula; _mes.cun_, meso-cuneiform; _nav_, navicular;
_tib_, tibia; _I-V_, first to fifth toes. (After Owen.)

The second sub-family, PHASCOLARCTINAE (with the Koala only), is thus
characterised:--Tail rudimentary; cheek-pouches present; superior incisors
three, but only one premolar above and below; {140} caecum extraordinarily
long; stomach with a cardiac gland; liver complicated by additional
furrows, without a free caudate lobe; no azygos lobe to lungs; vaginal
culs-de-sac free.

The third sub-family, PHASCOLOMYINAE, contrasts with the others as
follows:--Tail rudimentary; cheek-pouches present, but rudimentary; one
incisor on each side above, but no additional premolars; all the teeth
rootless; caecum not peculiar in shape; stomach with a cardiac gland; liver
complicated by secondary furrows, without a free caudate lobe; lung with an
azygos lobe; vaginal culs-de-sac free.

The last sub-family, TARSIPEDINAE, is thus defined:--Tail long; tongue
extensile; only one premolar; molars reduced; caecum absent.

[Illustration]

FIG. 69.--Vulpine Phalanger. _Trichosurus vulpecula._ × 1/6.

SUB-FAM. 1. PHALANGERINAE.--The genus _Phalanger_ embraces five species,
sometimes called by the generic name of _Cuscus_. They are largish animals
with short ears; only the end of the tail is naked. Of these animals only
one species is found in Australia itself, the rest inhabiting the islands
lying to the north. The Spotted Cuscus, _Ph. maculatus_, is in spite of its
vegetarian diet, and perhaps on account of its spots, spoken of as the
"Tiger Cat." Mr. Aflalo remarks of it that though provided with a
prehensile tail, it is little better as a climber than the tailless Koala.

_Trichosurus_, including the "True Phalangers," includes largish species,
which can be distinguished from the last genus by a chest-gland similar to
that which occurs in _Myrmecobius_ and some other Marsupials of the present
group. There are but two species, which are purely Australian. The
"Brush-tailed Opossum," _T. vulpecula_ (perhaps better known as
_Phalangista_ {141} _vulpina_), like its American pseudo-namesake (a true
Opossum, genus _Didelphys_), "plays 'possum" on occasions. The dental
formula is I 3/2 C 1/0 Pm 2/3 M 4/4. The ears are shortish.

The Ring-tailed Phalangers, _Pseudochirus_, are more widely distributed
than the last two genera; they range from Tasmania in the south to New
Guinea in the north. They are not, however, ring-tailed, though the tip of
the tail is generally white. As in the last genera, which have prehensile
tails, the end of this appendage is naked. The mammae are four. The tooth
formula is I 3/2 C 1/0 Pm 3/3 M 4/4. There are some ten species of the
genus.

The Striped Phalanger, _Dactylopsila trivirgata_, is an animal about a foot
long, whose identity can be ascertained by its striped, black and white
skin. It is an arboreal creature that lives apparently both on leaves and
grubs like so many arboreal creatures of quite different groups--Squirrels,
for instance, and New-World Monkeys. The tooth formula is I 3/3 C 1/6
Pm 3/2 M 4/4.

_Gymnobelideus leadbeateri_ is a small creature with a body 6 inches in
length. It is restricted to the colony of Victoria. The general look is
that of _Petaurus_; the ears are naked.

_Dromicia_ is a genus of Phalangers which although devoid of a parachute,
such as is possessed by certain genera that will be considered immediately,
is able to leap with great agility from branch to branch. The ears are
large and thin and almost naked; the tooth formula is I 3/2 C 1/0 Pm 3/3
M 4/4. They are minute creatures, the longest measuring, with the tail, but
10 inches. Dormouse-Phalanger is a name sometimes given to them. There are
four species, ranging from Tasmania to New Guinea. The name Dormouse as
applied to the genus seems to be owing to the way in which they hold a nut
in the paws when feeding. _D. nana_ is 4 inches long, with a tail of nearly
the same length. It is thick at the base.

_Distaechurus_ is the last genus of non-flying Phalangers. Its name refers
to the arrangement of the hairs on the tail, which are disposed on either
side in a row like the vane of a feather. The tooth formula is I 3/2 C 1/0
Pm 3/2 M 3/3, very nearly as in _Acrobates_. The ears are as in that genus.

_Petaurus_ is the first genus of the Flying Phalangers, all of which are
provided with a parachute-like expansion of the skin between the fore- and
hind-limbs; the ears are large and naked; and the tooth formula is I 3/2
C 1/0 Pm 3/3 M 4/4. There are three {142} species of the genus, which
extend through pretty well the entire Australian region. The term "flying"
as applied to these and the other "flying" genera is of course an
exaggeration. The animals cannot fly upwards; they can only descend in a
skimming fashion, the folds of skin breaking their fall. _P. breviceps_ is
perhaps the best-known species. The body is 8, the tail 9 inches long.

_Petauroides_ seems to be chiefly distinguished from _Petaurus_ by the fact
that, as in its ally _Dactylopsila_, the tail is partly naked terminally.
In _Petaurus_ and _Gymnobelideus_ the tail is bushy to the very end,
including its extreme tip below.

A third genus of Flying Phalangers is the minute _Acrobates_, which has a
distichous tail like that of _Distaechurus_. It is not more than 6 inches
in length including the tail. As to these Flying Phalangers it is
exceedingly instructive to observe that the same method of "flight" has
been apparently evolved three times; for the three genera are each of them
specially related to a separate type of non-flying Phalanger. The same
observation can be made about the Flying Squirrels, _Anomalurus_ and
_Sciuropterus_. The dental formula is I 3/2 C 1/0 Pm 3/3 M 3/3. The ears
are thinly clad with hair. There are four teats.

SUB-FAM. 2. PHASCOLARCTINAE.--The Koala, or Native Bear, _Phascolarctos
cinereus_, is the only representative of its sub-family. It is, like the
Wombat, aberrant in the lack of an obvious tail. The absence of this
appendage is curious in an arboreal creature whose near allies have a long
and prehensile one. The structure of the Koala was investigated by the late
Mr. W. A. Forbes.[89] There are some unexpected points of likeness to the
Wombat: thus they agree in the absence of the tail, in the structure of the
stomach, and in the great subdivision of the lobes of the liver. The brain,
however, is smooth, and the caecum is exceedingly large and complicated in
structure, that of the Wombat being short. That both animals have
cheek-pouches is perhaps due to similar habits of temporarily storing
masses of food. This animal has only eleven pairs of ribs. The tail has
only seven or eight vertebra, and these have no chevron-bones.

A peculiarity of the skull is seen in the great size of the alisphenoid
bulla, which is comparable in size and appearance with that of the Pig. As
in the Kangaroos, the atlas is incomplete below. {143}

The tooth formula of the genus is I 3/1 C 1/0 Pm 1/1 M 4/(4 or 5). The
additional lower molar seems to be exceptional, and has been found in one
specimen only.

In the alimentary tract the most remarkable structure is the large
intestine, which is very capacious for the first 28 inches or so of its
course. This section of the colon is lined with rugae precisely like those
which are found in the caecum. These folds, which at first are some twelve
in number, fuse lower down, and by the time that the colon approaches the
external orifice are reduced to five. Similar folds, as already stated,
occur in the caecum, but do not extend as far as its blind end. The caecum
is proportionately and actually larger than in any other Marsupial. The
gall-bladder is unusually elongated.

[Illustration]

FIG. 70.--Koala. _Phascolarctos cinereus._ × 1/9.

The Koala is mainly crepuscular or nocturnal in its habits. It feeds so
exclusively upon the leaves of the gum-tree (_Eucalyptus_) that it is
impossible to keep the creature long in captivity in lands where that
particular kind of food is not available.

The female, though she seems to bear but a single young one, which is
carried on the back after the fashion of some Opossums, has two nipples.
The animal's slow habits seem to require a nocturnal and retired life. It
is about as lethargic as the Sloth, and it is said to further resemble that
animal in clinging firmly to a branch even after it is shot. {144}

[Illustration]

FIG. 71.--Wombat. _Phascolomys wombat._ × 1/12.

SUB-FAM. 3. PHASCOLOMYINAE.--_Phascolomys_, the Wombat, is the only genus
of this sub-family. This animal has the appearance of a heavily-built
Marmot, like which it has a mere stump for a tail, and a pair of strong
chisel-shaped and Rodent-like incisors, which, however, differ from those
of Rodents in having a complete coating of cement. All the teeth of the
animal are rootless, and there are no canines. The incisors have enamel on
the front and lateral faces only. The dental formula is I 1/1 C 0/0 Pm 1/1
M 4/4. The affinities with other Diprotodont Marsupials are shown by the
commencing syndactyly of the second and third toes. The rhinarium is naked
or hairy. There is a rudimentary cheek-pouch, as in _Phascolarctos_. The
Wombat has, like the Koala, and also the Beaver--which does away with some
of the value of the comparison--a peculiar gland-patch in the stomach, a
raised area of collected glands. In no other Marsupial is such a structure
found, "whilst in the two forms under consideration its identity is almost
precise. That such a unique structure should have been independently
developed in two forms unrelated to each other, appears to me to be in the
highest degree improbable." This is Mr. Forbes' opinion. It might be
strengthened by adding the observation that, as there are other points of
likeness between the Wombat and the Koala, it seems more unlikely that a
structure so nearly identical should have been twice {145} developed in two
not very distant forms. As in the Kangaroos, the atlas is open below. _Ph.
ursinus_ has 15 ribs; the other species the normal (for Marsupials) 13.
Other points of likeness will be mentioned under the description of the
Koala. These animals mainly feed upon roots; they live in companies in
burrows. There are three species--_Ph. ursinus_, _Ph. latifrons_, and _Ph.
mitchelli_. _Ph. ursinus_ is Tasmanian in range, the other two species
South Australian.

[Illustration]

FIG. 72.--Skull of Wombat. _Phascolomys wombat._ (Lateral view.) _ang_,
Angular process; _cond_, condyle of mandible; _ex.oc_, exoccipital;
_ext.aud_, opening of bony auditory meatus; _ju_, jugal; _lcr_, lachrymal;
_max_, maxilla; _nas_, nasal; _p.max_, premaxilla; _sq_, squamosal; _ty_,
tympanic. (From Parker and Haswell's _Zoology_.)

SUB-FAM. 4. TARSIPEDINAE.--The genus _Tarsipes_ ought perhaps to be removed
from the present family. There is but a single species, which is a small
creature of 7 inches in total length, of which the tail measures 4 inches.
The teeth are much dwindled, the formula being I 2/1 C 1/0 Pm 1/0 M 3/3 =
22. The lower incisors are procumbent. The lower jaw, moreover, has not the
characteristic Marsupial inflection. The intestinal canal is without the
caecum present in the remaining Phalangeridae. It is a curious fact that
this aberrant little Phalanger should come from Western Australia, like the
even more aberrant _Myrmecobius_. Like the latter also, _Tarsipes_ has a
long exsertile tongue, with which, however, it extracts honey from flowers.
Probably it also catches minute insects in the corollas of the flowers. It
has been proved, in fact, that in captivity at any rate the animal is
insectivorous; for it has been known to eat moths.

FAM. 3. EPANORTHIDAE.--The extinct Epanorthidae of {146} Patagonia are
represented to-day by a small Marsupial which has been rediscovered within
the last two or three years. This little animal, formerly called
_Hyracodon_ (a pre-occupied name), is now termed _Caenolestes_, and is a
native of Colombia and Ecuador. There are two species, and of these _C.
obscurus_ is called by the inhabitants "Raton runcho," which means
opossum-rat. It lives apparently upon bird's eggs and small birds, though
it belongs to the Diprotodont division of the Marsupials. _Caenolestes_,
however, although diprotodont, has not the syndactylous character of the
digits of the feet already referred to in the Kangaroos and their allies.
The pouch is small and rudimentary. The dentition is I 4/3 C 1/1 Pm 3/3
M 4/4 = 46, and the teeth are said by Mr. Thomas to be much like those of
the Australian _Dromicia_.[90]

In the skull a peculiarity which does not bear upon its affinities to other
Marsupials, but is still interesting, is mentioned by Mr. Thomas. The
nasals are not sufficiently prolonged to meet the upper edge of the
maxillae, and so a vacuity is left, as in the skulls of many Ruminants
(_e.g._ the Sable Antelope). The palate is very imperfect; the foramina,
which render it so, reach as far forward as the last premolar. The lower
jaw has quite the appearance of that of a _Macropus_ or _Phalanger_, with
long and forwardly projecting incisors.

EXTINCT DIPROTODONTS.--The great _Diprotodon_ is a creature with a skull a
yard long, which must have been of the size of a large Rhinoceros. Though
closely allied to _Macropus_, it seems that this great beast did not hop
after the fashion of a Kangaroo, its limbs being of a more equal size than
in the Kangaroo. Recently some further remains of _Diprotodon_ have been
discovered in a lake known as Lake Mulligan, where they had apparently been
bogged. Professor Stirling has contributed an account of these remains,
which fills up a considerable gap in our knowledge. He has been able to
state the structure of the fore- and hind-limbs. Both limbs are
pentadactyle, the fingers of the fore-limb being approximately equal in
length and general development. In the hind-limb the hallux is small, and
consists of the metatarsal only. This bone is fixed in the position of
"extreme abduction," and is suggestive of an arboreal limb. Digits two and
three may have {147} been syndactylous, and the authors of the account[91]
of these bones think that the fourth toe may have shared in this
syndactyly. The metatarsal of the fifth digit is enormously expanded at its
edge, and seems to have furnished a strong support to the creature; this is
also seen in the metacarpal of the fore-limb. Probably, therefore,
_Diprotodon_ was quadrupedal in its mode of progression, with the emphasis
laid upon the little finger and the little toe instead of, as in ourselves,
the first toe. The hind-foot of the _Diprotodon_ could not be more unlike
that of a Kangaroo than it actually is.

[Illustration]

[Illustration]

FIG. 73.--_Diprotodon australis._ (After Owen.)

FIG. 74.--_Thylacoleo carnifex._ Side view of skull. (After Flower.)

Another giant among these Marsupials was the genus _Thylacoleo_, whose name
was given to it by Sir Richard Owen on the view that it was a Marsupial
Tiger. Sir W. Flower has, however, controverted this opinion, and the genus
is in fact, in spite of its large size, closely allied to the Phalangers
and {148} Cuscuses.[92] The dental formula is I 3/1 C 1/0 Pm 3/1 M 1/2; the
last premolar is a great blade-shaped tooth like that of _Potorous_.

_Nototherium_ was a creature smaller than _Diprotodon_, but still of large
size; it is believed to have been a burrowing creature, and to connect the
Wombats with _Diprotodon_. More certainly allied to the existing Wombat was
_Phascolonus_, a Wombat as big as a Tapir.

[Illustration]

FIG. 75.--_Nototherium mitchelli._ Side view of skull. × 1/6. (After Owen.)

Of extinct American Diprotodonts the Epanorthidae, already referred to in
connexion with the living _Caenolestes_, were the most prominent forms. The
genus _Epanorthus_ occurs in the Santa Cruz formation of Patagonia, which
is believed to be Miocene. The incisors are three in the upper jaw; and the
single incisor of each ramus of the lower jaw is a great chisel-shaped,
cutting instrument.

_Abderites_ is also typically Diprotodont by reason of the large projecting
incisors of the lower jaw. It has a large cutting tooth in the lower jaw,
which appears to be the last premolar, and is thus comparable to the great
cutting tooth of the lower jaw and of the upper jaw of the extinct
Phalanger, _Thylacoleo_. {149} It may also be comparable to the great
premolar of such Multituberculata as _Ptilodus_ and _Plagiaulax_. It is,
moreover, marked with vertical grooves.

An interesting form, which is unfortunately but little known, is the
Australian and Pleistocene genus _Triclis_, with one species, _T.
oscillans_. In having a minute canine tooth in the lower jaw it agrees with
some Phalangeridae, and being otherwise closely allied to _Hypsiprymnodon_,
it unites the Macropodidae with the Phalangeridae.

SUB-ORDER 2. POLYPROTODONTIA.

In this mainly carnivorous or insectivorous division of the Marsupials the
incisors are four or five on each side of the upper jaw, and one or two
fewer in the lower jaw. Figs. 76 and 77 illustrate the Polyprotodont and
Diprotodont dentitions. The canines are those of flesh-eaters and so are
the molars, being as a rule sharply cuspidate. As a rule, which has an
exception in the Peramelidae, there is no syndactylism of toes in the
hind-foot. This sub-order is at the present day Australian and American in
its range.

[Illustration]

FIG. 76.--Front view of the skull of Tasmanian Devil (_Sarcophilus
ursinus_), showing Polyprotodont and carnivorous dentition. (After Flower.)

FAM. 1. DASYURIDAE.--This family consists of Marsupials which are generally
pentadactylous, but with occasionally the hallux missing. The tail is long
but not prehensile. The pouch is present or absent. The teeth vary in the
different genera, but {150} the upper incisors are never less than three,
and may be as many as five in the upper jaw and six in the lower. The
canines are trenchant. There is no caecum.

[Illustration]

FIG. 77.--Front view of skull of Koala (_Phascolarctos cinereus_),
illustrating Diprotodont and herbivorous dentition. (From Flower.)

[Illustration]

FIG. 78.--Longitudinal section of the skull of the Thylacine (_Thylacinus
cynocephalus_). × ½. _a_, Angular process of mandible; _AS_, alisphenoid;
_BO_, basioccipital; _BS_, basisphenoid; _cd_, condyle of mandible; _ET_,
ethmoturbinal; _Ex.O_, exoccipital; _Fr_, frontal; _ME_, ossified portion
of mesethmoid; _MT_, maxilloturbinal; _Mx_, maxilla; _Na_, nasal; _OS_,
orbitosphenoid; _Pa_, parietal; _Per_, periotic; _Pl_, palatine; _PMx_,
premaxilla; _PS_, presphenoid; _Pt_, pterygoid; _SO_, supraoccipital; _Sq_,
squamosal; _Vo_, vomer. (From Flower's _Osteology_.)

The genus _Thylacinus_ contains but a single species, which is now limited
to Tasmania, and is generally known as the Tasmanian Wolf. It has the build
of an ordinary Wolf, and is of about the same size. The hinder part of the
body is marked with a series of black transverse bands. The hallux is
entirely wanting; the pouch opens backwards. The marsupial bones are minute
and unossified. The dental formula is I 4/3 C 1/1 Pm 3/3 M 4/4 = 46. There
are four mammae. This animal, now confined to Tasmania, {151} is getting
rarer on account of its sheep-killing propensities, and the consequent war
of extermination declared upon it by the colonists. It will, however, feed
upon other animals; and it is related that the first specimen ever captured
had in its stomach the remains of an Echidna! Mr. Thomas thinks that the
persistence of this and of some of the other larger carnivorous Marsupials
in Tasmania after their extinction in Australia is not unconnected with the
advent of the Dingo. But it is stated that the Thylacine is quite capable
of keeping even a pack of dogs at bay.

[Illustration]

FIG. 79.--Tasmanian Devil. _Sarcophilus ursinus._ × 1/10.

The genus _Sarcophilus_ has been frequently confounded with the next, but
it is kept apart by Mr. Thomas, who follows Cuvier in this. An alternative
generic name is _Diabolus_, which, like the first name, refers to the
habits and character of the single species which this genus contains. The
genus is more like _Thylacinus_ than is _Dasyurus_. The hallux is wanting,
and the teeth, though fewer in number (42), resemble those of the Thylacine
more closely than do those of the Dasyure. The species is called _S.
ursinus_, the popular name being Tasmanian Devil. It is black with a
variable number of white patches on the body. It is of about the size of a
Badger, and is, like the Thylacine, a nocturnal animal. The Tasmanian Devil
is said to be one of the most ferocious of animals, and to express its
ferocity by a "yelling growl."

{152} [Illustration]

FIG. 80.--Skull of _Dasyurus_. (Lateral view.) _al.sph_, Alisphenoid;
_ang_, angular process of mandible; _fr_, frontal; _ju_, jugal; _lcr_,
lachrymal; _max_, maxilla; _nas_, nasal; _oc.cond_, occipital condyle;
_par_, parietal; _par.oc_, paroccipital process; _p.max_, premaxilla;
_s.oc_, supraoccipital; _sq_, squamosal; _sq_', zygomatic process of
squamosal. (From Parker and Haswell's _Zoology_.)

[Illustration]

FIG. 81.--Dasyure. _Dasyurus viverrinus_. × 1/5. (After Vogt and Specht.)

The next genus of this family, _Dasyurus_, comprises five species, which
range over the whole of the Papuan and Australian sub-regions. The general
form is Viverrine, and the hallux is sometimes present though small. The
dental formula is as in the last genus, but the teeth "are more
insectivorous in their character." There are six or eight mammae. The
members of this genus are grey or brown, and spotted with white; they are
all arboreal, and feed largely upon birds and their eggs. Mr. Thomas has
pointed out that in two species, _D. viverrinus_ and _D. geoffroyi_, the
striae upon the foot-pads are absent, and that therefore these at least are
probably not so purely arboreal as the rest. The animals are not diurnal,
and during the day hide themselves in the hollow trunks of trees. They are
spoken of as "Native Cats," but have the general habits of Martens. _D.
maculatus_ is common in Tasmania, but is rare in Australia, thus
"approaching the condition now exhibited by the Thylacine and {153}
Tasmanian Devil, namely, complete extermination in Australia, where both
once lived." _D. hallucatus_ shows an approach to _Phascologale_ in its
five-toed hind-feet and slender build.

_Phascologale_ is a genus which, like the last, is usually arboreal
(although not _P. virginiae_ of North Queensland), but is of much smaller
size, the species not exceeding the dimensions of a rat. They have no
spots, but there is sometimes a stripe down the back. There are thirteen
species, which have the same range as the last genus. The hallux is present
though small, but the pouch is "practically obsolete," though there is a
small fold of skin behind the teats. The rhinarium is naked; the tail is
long, "bushy, crested, or nearly naked." The mammae are four to ten in
number. The dental formula is as in _Dasyurus_, and the teeth are not very
different in form; sometimes the last premolar is wanting. "The members of
this genus," remarks Mr. Thomas, "evidently take the place in the
Australian region filled in the Oriental by the Tupaiae, and in the
Neotropical by the smaller Opossums."

The genus _Sminthopsis_ comprises not more than four species, even smaller
than the last. The largest species, _S. virginiae_, is only 125 mm. in
length. The hallux is present, and there is a well-developed pouch. There
are forty-six teeth, as in the Dasyures. The feet are narrow with
granulated or hairy soles, whereas in _Phascologale_ they are broad with
smooth soles. The mammae are eight or ten. The genus ranges through
Australia and Tasmania.

The genus _Antechinomys_ has but a single species, which is a native of
Queensland and New South Wales. The build is Jerboa-like, and the animal
is, as might be inferred, terrestrial. The ears are very long, and the
limbs elongated; the hallux is absent; the teeth are exactly as in
_Sminthopsis_.

_Antechinomys_ has thirteen dorsal and seven lumbar vertebrae; three
sacrals and twenty-five caudals, the latter number being in excess of that
of its allies. The stomach is nearly globular, with approximated orifices;
the intestine measured 6.8 inches, a little more than twice the length of
the animal itself. _A. lanigera_ is a native of East Central Australia, and
appears to be entirely terrestrial in habit, and to progress by a series of
leaps--at any rate when going at full speed.

Professor Spencer, who found examples of this rare species, gives {154} an
interesting description of its habits. _Antechinomys_ has much the look of
the Australian Rat, _Hapalotis mitchelli_; and as the two animals lead a
similar kind of life, the resemblance is not unexpected. Professor Spencer
wonders why these creatures are saltatory in habit. The country which they
inhabit is arid, but with patches of grass and shrubs. For a big kangaroo
the advantage of the power of leaping over such obstacles may be obvious,
but not for the small and slender _Antechinomys_. The chief foes of this
rare Marsupial appear to be predatory birds; and Professor Spencer thinks
that the saltatory mode of progression may be more baffling to such
pursuers than even a rapid run.

The genus _Dasyuroides_ has been lately instituted by Professor Spencer for
a Marsupial from Central Australia somewhat intermediate between
_Sminthopsis_ and _Phascologale_. As there is but one species, the generic
will be considered with the specific characters. _D. byrnei_ is an animal
of about the size of the Common Rat. The hallux is absent. The tail is
fairly thick, but not "incrassated." There are six mammae, and the pouch is
but slightly developed, with two low lateral folds. The dentition is I 4/3
C 1/1 Pm 3/2 M 4/4. This Marsupial is nocturnal, and burrowing in habit.
Its food consists of insects.[93]

_Myrmecobius_ is so different from the last-described genera (DASYURINAE)
that it is usually separated from them as a sub-family MYRMECOBIINAE. The
animal is of a bright rufous colour, banded posteriorly with white. There
is no hallux, though the metatarsal belonging to that digit is present.
There are four mammae.[94] On the chest is a naked patch of some extent,
upon which open the ducts of a complex gland, which has been described and
figured by myself.[95] There is no pouch, but a tract of skin shows
indications of a pouch-like structure. The teeth are extraordinarily
numerous, fifty to fifty-four; the formula being I 4/3(4) C 1/1 Pm 3/3
M 5/6. Their resemblance to those of certain Jurassic Marsupials is dealt
with on p. 100.[96] In this matter lies of {155} course the chief interest
of the genus, which may be "an unmodified survivor from Mesozoic times, and
therefore from a time long before the Didelphyidae, Peramelidae, and
Dasyuridae were differentiated one from the other." Another ancient feature
(found in Jurassic mammals) is a mylo-hyoid groove upon the lower jaw,
which, however, is not always present, and its existence has therefore been
denied. The single species, _M. fasciatus_, is partly arboreal and partly
terrestrial in habit, and feeds upon ants. It is a Western and Southern
Australian form.

[Illustration]

FIG. 82.--Banded Australian Anteater. _Myrmecobius fasciatus._ × 1/5.

FAM. 2. DIDELPHYIDAE.--All the members of this family are pentadactylous.
The teeth are fifty in number, arranged thus: I 5/4 C 1/1 Pm 3/3 M 4/4. The
caecum is small; the pouch is generally absent; the tail generally long and
prehensile.

[Illustration]

FIG. 83.--Virginian Opossum. _Didelphys virginiana._ × 1/5. (After Vogt and
Specht.)

The genus _Didelphys_ contains most of the forms belonging to this family,
including as it does some twenty-three species. The Opossums are mainly
arboreal animals, insectivorous in their food; but the larger species eat
reptiles, birds, and their eggs. Several of the small species carry their
young, when able to leave the teats, on {156} their back, the tails of the
young being wrapped round that of the mother. It is not only the pouched
species which carry their young in something of this fashion. Azara's
Opossum, an animal as big as a cat, is said to carry its eleven young ones
(themselves as large as rats) on the back, though their foothold does not
appear to be strengthened by intertwining the tails. Even with this huge
family on her back, the mother can climb trees with considerable alacrity.
The mammae are seven to twenty-five in number. The genus has been lately
split up into a number of genera, _Marmosa_, _Dromiciops_, _Peramys_, etc.

[Illustration]

FIG. 84.--Thick tailed Opossum. _Didelphys crassicaudata._ × 1/5.

_Chironectes_ is hardly different from _Didelphys_. It has webbed
hind-feet, and is aquatic in habit. The one species of the genus is known
as the Yapock, and is a Central and South American form. It is of about the
size of a large rat, and appears to be an expert diver after the fish upon
which it lives.

FAM. 3. PERAMELIDAE.--The Bandicoots, although clearly belonging to the
Polyprotodont Marsupials, yet agree with the Diprotodonts in the fact that
the second and third toes of the feet are bound up in a common integument,
which is not the case with the Diprotodont _Caenolestes_. The hind-feet are
longer than the front; of the former limb, two or three of the fingers
alone are long and functional; the others are rudimentary or absent. Tail
long, hairy, and non-prehensile. Dentition I 5/3 C 1/1 Pm 3/3 M 4/4 = 48,
or sometimes, owing to the absence of a pair of upper incisors, 46. There
is a caecum.

{157} [Illustration]

FIG. 85.--Bones of manus. A, of _Choeropus castanotis_. × 2. B, of
Bandicoot (_Perameles_). × 1½. _c_, Cuneiform; _l_, lunar; _m_, magnum;
_R_, radius; _s_, scaphoid; _td_, trapezoid; _tm_, trapezium; _u_,
unciform; _U_, ulna; _I-V_, digits. (From Flower's _Osteology_.)

[Illustration]

FIG. 86.--Rabbit Bandicoot. _Peragale lagotis._ × 1/5.

The genus _Peragale_, the Rabbit-Bandicoots, consists of two species
entirely Australian in range. The enormous ears (whence "Rabbit" Bandicoot)
distinguish this genus from _Perameles_. The pouch opens backwards, and
there are eight mammae. _P. lagotis_, the only species about whose ways of
life anything is {158} known, burrows in the soil, whence it extracts
grubs; it is also a grass-feeder, and it is said that its likeness to a
Rabbit in appearance is strengthened by its similarity in flavour!

_Perameles_ is a genus consisting of twelve species, which are found in
Tasmania, Australia, and New Guinea. Like the last genus, from which it
does not widely differ in other points, _Perameles_ consists of species
which combine insectivorous and vegetarian habits. One species is said to
become in captivity an expert in catching mice. The pouch opens backwards,
and there are six or eight mammae.

[Illustration]

FIG. 87.--Pig-footed Bandicoot. _Choeropus castanotis._ × 1/3.

The last genus of this family is _Choeropus_, containing but one species,
_Ch. castanotis_. It is confined to the Australian continent. It is to be
distinguished from the last two by the fact that there are only two
functional digits, the second and third, in the fore-limb; the fourth is
rudimentary; the other two are absent. It burrows, and is omnivorous like
its allies. The two metacarpals that are developed are very long and
closely apposed; they have hence a remarkably pig-like aspect, and justify
its name. The pouch opens backwards, and there are eight mammae.

FAM. 4. NOTORYCTIDAE.--This family contains but a single genus and species,
the recently-discovered _Notoryctes typhlops_.[97]

{159} We may regard as family-characters the pentadactyle limbs, the
existence of three pairs of incisors in the lower and four in the upper
jaw; and the tritubercular nature of the upper molars. _Notoryctes
typhlops_, the "Marsupial Mole" as it has been termed, was originally
discovered by Professor Stirling in Central South Australia. It is a
burrowing creature, clothed in a silky fur of a pale golden red, without
external ears. It has been compared in appearance with _Chrysochloris_, the
Cape Golden Mole, and the eminent palaeontologist, Professor Cope, has even
insisted upon a real genetic affinity. Edentate affinities have also been
suggested. But _Notoryctes_ has a small pouch opening backwards as in other
Polyprotodonts,[98] and as it also possesses marsupial bones it must
undoubtedly be referred to the Marsupialia. The animal shows many curious
adaptations to its underground mode of life. Certain of the vertebrae in
the neck and in the lumbar region are firmly welded together, giving of
course a strength of push, and suggesting the Armadillos; the claws of the
third and fourth front-toes are greatly enlarged, and must be efficient
digging organs. The track of the animal is like that of a railway in
mountainous country; it burrows for a short distance, emerges, and then
descending beneath the surface re-emerges. The red colour of the fur is
said to be in harmony with the arid soil in which it lives. The native name
of the creature is "Urquamata." It feeds upon ants and other insects.

[Illustration]

FIG. 88.--Australian Marsupial Mole. _Notoryctes typhlops._ × ¼.

EXTINCT POLYPROTODONTS.--Of extinct Polyprotodonts (apart from those
Mesozoic forms which are considered on p. 100) extinct species of
_Thylacinus_ and _Dasyurus_ are known from {160} Australia. The most
interesting fact in connexion with the Tertiary Polyprotodonts is the
existence in South America of such genera as _Prothylacinus_ and
_Amphiproviverra_, which are not merely Polyprotodonts but definitely
Dasyures, and not referable to the Didelphyidae.

These forms have been included in an order, SPARASSODONTA. But it is not by
any means certain whether these forms are rightly placed in the
neighbourhood of the carnivorous Marsupials; it is possible that they ought
to be relegated to the Creodonta or to their allies. Their structure is in
fact somewhat intermediate between those two groups. The teeth seem to be
carnivorous and Marsupial-like in form; but as already mentioned, in
connexion with the general structure of teeth, more than a single premolar
is replaced. These animals in fact, in so far as regards their teeth, are
midway between the Marsupials and the typical Eutheria. The angle of the
lower jaw is inflected, but the palate is not marked by deficient
ossification. At least this is not the case with all the members of the
group. Whether the small _Microbiotherium_, which is made the type of a
family, is rightly referred here is not certain. This animal had palatine
vacuities as well as an inflected angle to the lower jaw.

       *       *       *       *       *


{161}

CHAPTER VIII

EDENTATA--GANODONTA

ORDER II. EDENTATA

Terrestrial, partly subterranean, or arboreal creatures of quite small to
gigantic size (some extinct genera), with frequently a covering of scales
or bony scutes. Limbs clawed. Teeth either totally absent or, if present,
imperfect in structure, being without enamel, and not forming a complete
series; incisors and canines being as a rule absent. Teats axillary,
pectoral, or inguinal.[99] Retia mirabilia very common in the extremities.

To this group the name of Bruta was given by Linnaeus, but then it included
not only the families which we now place in the modern order Edentata, but
also the Elephant and the genus _Trichechus_. Mr. Thomas has proposed to
change the name into Paratheria, which name is suggestive of what he and
some others think concerning the systematic position of the group, _i.e._
that it is not to be placed in the Eutherian group of mammals at all, but
represents a separate twig which has arisen with the Eutheria from a low
mammalian stock. This view can hardly be accepted if the Ganodonta--which
will be treated of presently--be really ancestral Edentates, for they are
not in any way a Prototherian mammalian group, so far as their remains
enable us to judge.

The Edentata contain the Sloths, Ant-bears, Armadillos, _Manis_ and
_Orycteropus_, among living forms. The great Ground-Sloths, _Megatherium_,
etc., and Armadillos, _Glyptodon_, etc., represent the extinct forms.

The name that has been applied to this group is inappropriate {162}
inasmuch as many Edentates have teeth. It is, however, by a number of small
tooth-characters that the order can be defined. Thus if teeth are present
they are simple in structure, without enamel in the adult condition, though
a rudimentary enamel-organ has been discovered in an Armadillo. The teeth,
moreover, are not found in the anterior part of the mouth, and they grow
from persistent pulps; neither is there much differentiation among them. It
is not possible, however, to speak of the Edentates as quite homodont,
since in _Orycteropus_ there are large cheek-teeth; but there is at any
rate not a marked heterodonty in that or in any other Edentate. It used to
be said that the Edentates were monophyodont. But the Armadillo _Tatusia_
was subsequently found to possess a second suppressed dentition, and after
this discovery Mr. Thomas proved that _Orycteropus_ is also diphyodont.
Since then other Armadillos have been shown to be diphyodont; and the whole
group therefore, so far as concerns those members that have teeth, may in
all probability be regarded as typically mammalian in this respect.

These characters are slender enough, but there seem to be no others by
means of which the members of this order can be satisfactorily linked
together. The fact is, that we have here a polymorphic order which contains
in all probability representatives of at least two separate orders. We have
at present a very few, and these perhaps highly modified, descendants of a
large and diverse group of mammals. For convenience' sake they will be all
treated of under the head of Edentata.

Although for the probable reasons already stated it is a hard matter to
frame such a definition as will include all existing Edentates, it is easy
enough to define two groups in this heterogeneous order; to define one
group we should say, rather, and then to regard the leavings as forming
another not so easily definable a group.

The perfectly-definable group is that which includes the American
Anteaters, the Armadillos, and the Sloths. In all these creatures, which
may certainly be regarded as representing on their own account as many
family types, there are a number of important and highly-characteristic
anatomical features which they share in common. So exceedingly different
are these three types in general appearance and (correlated with that) in
way of life that these common characters acquire increased importance.
{163}

[Illustration]

FIG. 89.--Great Anteater (_Myrmecophaga jubata_). A, Side view of twelfth
and thirteenth thoracic vertebrae. B, Posterior surface of second lumbar
vertebra. C, Anterior surface of third lumbar vertebra, × 2/3. _az_,
Anterior zygapophysis; _az_^1, _az_^2, _az_^3, additional anterior,
articular facets; _cc_, facet for capitulum of rib; _m_, metapophysis;
_pz_, posterior zygapophysis; _pz_^1, _pz_^2, _pz_^3, additional posterior
articular facets; _t_, transverse process; _tc_, facet for articulation of
tubercle of rib. (From Flower's _Osteology_.)

The first of these characters is the series of additional zygapophyses on
the posterior dorsal and lumbar vertebrae; these are very clear in the
Anteaters and Armadillos; less clear, but still obviously represented, in
the Sloths. In the second place, they all possess a clavicle, rudimentary,
it is true, in the Great Ant-bear, but still present. Thirdly, the testes
are abdominal throughout life, a character which they share with such
lowly-organised animals as the Monotremata and the Whales. Finally, and
this is by no means a matter to be overlooked, not only are all the
existing members of this group American in range, but there is no evidence
to prove that they have ever existed elsewhere. No European or Old-World
{164} representatives have as yet been discovered which can be referred to
the Anteater, Armadillo, or Sloth type with certainty.[100]

Of these American forms, which will be treated of first, the Armadillos are
further apart from either Sloths or Anteaters than the last two are from
each other. The name XENARTHRA has been suggested for the American
Edentates with "abnormal" vertebral articulations; the corresponding
NOMARTHRA includes the Old-World forms.

[Illustration]

FIG. 90.--Right scapula and clavicle of Two-toed Sloth (_Choloepus
hoffmanni_). × 1-2/3. _a_, Acromion; _af_, prescapular fossa; _c_,
coracoid; _cl_, clavicle; _csf_, coraco-scapular foramen; _gc_, glenoid
cavity; _pf_, postscapular fossa. (From Flower's _Osteology_.)

Between the Sloths and Anteaters the extinct _Megatherium_ and some of its
allies are to a certain extent intermediate. But it may be pointed out in
the first place that there are certain important resemblances between the
living forms. In both, retia mirabilia are developed in the tail (in spite
of its reduction in the Sloths) and in the limbs. But, as is well known,
retia are also found in other mammals far removed in the series from these
under consideration. The reproductive organs generally are very similar,
and they have both a dome-shaped and deciduate placenta. The latter
character they share with the Armadillos and with the Aard Vark; _Manis_
having a non-deciduate placenta which is, like that of the Carnivora,
zonary in form. The Edentates, at any rate the American forms, have a
double vena cava posterior and no azygos vein. This condition is also met
with among Whales.

Osteologically the Sloths and Anteaters are united by the fact that the
coracoid becomes fused with the coracoid border of the scapula, thus
forming a foramen; the importance of this character is, however, discounted
by its occurrence in three genera of Cebidae.

The above facts embody the views of Sir William Flower.[101]

{165} A subsequent study of the brain and of the muscles of these animals
has led to results not entirely in harmony with these views.

Dr. Elliot Smith is of opinion,[102] after an exhaustive study of the
Edentate brain, that in this region of the body the present group shows
very decided points of likeness to the Carnivora; that is, so far as
concerns the Anteaters. On the other hand, _Orycteropus_ is as distinctly
comparable with a primitive Ungulate type, such as is exemplified by
_Moschus_. "If the brain of _Orycteropus_," he remarks, "were given to an
anatomist acquainted with all the other variations of the mammalian type of
brain, there is probably only one feature which would lead him to hesitate
in describing it as an exceedingly simple Ungulate brain. That one feature
is the high degree of macrosmatism.[103] _Manis_, on the other hand, does
not come especially near to _Orycteropus_. The brain of _Manis_ conforms to
a simple type of architecture, which agrees in many points with both those
of _Orycteropus_ and the American Edentates; there is not sufficient
evidence to show which type it really favours." Elliot Smith would, in
fact, agree with Max Weber that it is better, if a division is to be made,
to divide the group into three orders:--the Xenarthra (Sloths, Anteaters,
and Armadillos), Tubulidentata (_Orycteropus_), and Squamata (_Manis_),
instead of into Xenarthra and Nomarthra.

Messrs. Windle and Parsons[104] are disposed to see in muscular
similarities reasons for uniting _Manis_ with the American Edentates,
though they confess to being unable to place _Orycteropus_; in this animal,
they say, "we are more struck by the generalised mammalian arrangement of
its muscles than by any special Edentate characters. There are, however,
two muscles in _Orycteropus_ which show peculiarities not found elsewhere
than in the Edentates";--the triceps, which has more than one scapular
head, and the tibialis posticus, which is double. They conclude that
_Orycteropus_ "presents some feeble claims to be taken into the order."

We shall here adopt the following divisions. {166}

SUB-ORDER 1. XENARTHRA.

FAM. 1. MYRMECOPHAGIDAE.--The family Myrmecophagidae contains three genera,
all South American in range. These genera, _Myrmecophaga_, _Tamandua_, and
_Cycloturus_, agree greatly in their outward form. They are all without
teeth, and have long snouts and long protrusible tongues. The fur is thick,
and they have powerful claws wherewith to break down the strong ant-hills
upon whose inhabitants they feed. _Tamandua_ and _Cycloturus_ are arboreal,
_Myrmecophaga_ is terrestrial in habit. The claws of the arboreal forms are
useful to destroy the bark, and thus bring to light insects which lurk in
such situations.

[Illustration]

FIG. 91.--Great Anteater. _Myrmecophaga jubata._ × 1/10.

The genus _Myrmecophaga_ contains but one species, the Great Anteater,
_Myrmecophaga jubata_. It is a large and handsome animal, with long,
shaggy, greyish-black hair and a broad white stripe across the shoulder.
The coloration is similar in the two sexes. Including the long and bushy
tail it reaches a length of over 7 feet. It is on account of its long
tongue and greatly developed salivary glands that this and the allied
genera were originally placed with _Manis_. It is the submaxillary glands
which are so enormous; they extend back over the chest, and open by three
distinct ducts, of which two unite just before the external orifice. {167}
Along their course these ducts are provided with a sphincter muscle, which
squeezes the secretion towards the external orifice into the mouth-cavity.
The stomach is somewhat gizzard-like. The intestine has no caecum.[105]

The Anteater's great claws are not only serviceable in tearing up the
ground to get at its food; armed with them he does not fear, as Mr.
Waterton remarked, "the fatal pressure of the serpent's fold or the teeth
of the famished jaguar." An Anteater, too, is more than a match for a big
dog, and will rip open its belly with the claws while the dog is vainly
trying to make an impression with its teeth upon the shaggy hair.

_Tamandua_ is a smaller animal than _Myrmecophaga_, and, as has been
stated, is arboreal; associated with this habit is a prehensile tail. Like
the last genus, _Tamandua_ has a rudimentary clavicle, this bone being well
developed in the little _Cycloturus_.

[Illustration]

FIG. 92.--Skull of Anteater (_Myrmecophaga_). Lateral view, _al.sph_,
Alisphenoid; _cond_, condyle of mandible; _cor_, coronoid process of
mandible; _ex.oc_, exoccipital; _ext.aud_, external auditory meatus; _fr_,
frontal; _ju_, jugal; _lcr_, lachrymal; _max_, maxilla; _nas_, nasal;
_occ.cond_, occipital condyle; _pal_, palatine; _par_, parietal; _p.max_,
premaxilla; _s.oc_, supraoccipital; _sq_, squamosal; _ty_, tympanic. (From
Parker and Haswell's _Zoology_).

The skull of the Anteater[106] is very long and low; the fore-part is
tubular, and there appear to be no traces of teeth. The premaxilla is very
small; the zygomatic arch is imperfect, and does not reach the squamosal
behind. A curious feature of this genus, which it shares with some Dolphins
and other Whales, is that the pterygoid bones develop palatine plates which
meet each other in the middle line, and thus shift the opening of the {168}
posterior nares backwards. This is also, of course, a character of various
lower vertebrates. Another Whale-like character in the skull is the weak
character of the mandible, which does not give off a marked coronoid
process. But then in neither group is there much mastication. The tympanic,
periotic and squamosal are ankylosed together. A peculiarity of the
cervical vertebrae is that (as in the Camels) the vertebrarterial canal of
several of the vertebrae perforates the pedicle obliquely. There are
fifteen or sixteen dorsal and three or two lumbar vertebrae. The additional
zygapophyses upon the former have been already referred to. The mode of
articulation of the ribs is highly singular.

[Illustration]

FIG. 93.--Skull of Anteater (_Myrmecophaga_). Ventral view. Letters as in
Fig. 92. In addition, _b.oc_, basioccipital; _glen_, glenoid surface for
mandible; _pter_, pterygoid. (From Parker and Haswell's _Zoology_.)

[Illustration]

FIG. 94.--Side view of three mesosternal segments of a young Anteater
(_Tamandua_), showing the mode of articulation of the sternal rib (_sr_).
_mst_, The upper or inner surface of the mesosternal segment; _sy_, the
synovial articulation between the segments. (From Flower's _Osteology_,
after Parker.)

Each segment of the sternum (of which there are eight) is separated from
the next by a synovial membrane: and it has on either side two facets for
articulation with the ribs. The way in {169} which these latter bones are
connected with the sternum is curiously like their mode of connexion with
the spinal column at their other end. With this may be possibly compared
the double articulation of the single rib (which articulates with the
sternum) in the Rorquals. In _Cycloturus_ this mode of articulation does
not occur.

The manus of _Myrmecophaga_ is five-fingered. Of these the third digit (as
in Perissodactyles) is the most prominent; it is at least double the width
of the second or third finger; the pollex is very slender. In the little
_Cycloturus_ this is carried to a greater extent: the third digit is
relatively enormous; the first and the fourth have become quite
rudimentary; while the fifth is only just recognisable as a minute
ossification.

[Illustration]

FIG. 95.--A, Manus of Great Anteater (_Myrmecophaga jubata_). × 1/3. B,
Manus of Little Anteater (_Cycloturus didactylus_). × 2. _c_, Cuneiform;
_l_, lunar; _m_, magnum; _p_, pisiform; _s_, scaphoid; _td_, trapezoid;
_tm_, trapezium; _u_, unciform; _I-V_, digits. (From Flower's _Osteology_.)

The chevron-bones in the tail surround a well-developed rete mirabile, a
rete being found in precisely the same position in the Eastern _Manis_.
_Tamandua_ has also retia, which are also found in the Spider-monkeys.

_Cycloturus_ is by far the smallest of the Anteaters. It has {170} only two
toes on the fore-feet. It is to be distinguished, anatomically, from its
larger relatives by the complete clavicle, and by the fact that the
pterygoids do not meet in the middle line of the skull. The ribs, too, are
unusually wide, as in the Whale _Neobalaena_, and form a bony encasement
for the body. It has two small caeca. Of fossil Anteaters but little is
known. The most interesting form is _Scotaeops_, interesting because it has
two small back teeth, which are totally lost in its living allies. The huge
Patagonian extinct bird _Phororhacos_, first known by a lower jaw, was at
one time regarded as a member of this group on account of the form and
edentulous character of the jaw.

[Illustration]

FIG. 96.--Unau, or Two-toed Sloth. _Choloepus didactylus._ × 1/5. (After
Vogt and Specht.)

{171} [Illustration]

FIG. 97.--Skull of Three-toed Sloth. _Bradypus tridactylus._ Lateral view.
_fr_, Frontal; _ju_, jugal; _lcr_, lachrymal; _max_, maxilla; _nas_, nasal;
_par_, parietal; _s.oc_, supra-occipital; _ty_, tympanic. (From Parker and
Haswell's _Zoology_.)

FAM. 2. BRADYPODIDAE.--The Sloths, genera _Bradypus_ and _Choloepus_, come,
as already stated, very near to the Anteaters, in spite of their striking
difference in appearance. The Sloths are purely arboreal creatures, with
strong recurved claws, which serve as hooks to keep them suspended from the
lower side of a branch. The three-toed sloth, _Bradypus_ (or "Ai"), has the
exceptional number of nine cervical vertebrae; the two-toed sloth,
_Choloepus hoffmanni_ (or "Unau"), has the equally exceptional number of
six. The hair is long and shaggy, and gets an adventitious green colour
from the presence of minute algae.[107] This gives to the animal the
appearance of a lichen-covered bough, a resemblance which is increased in
one species by an oval mark upon the back, which suggests forcibly a broken
end of such a branch. The likeness of a Sloth to its surroundings is
pointed out by Dr. Siemann,[108] who observed that a species occurring in
Nicaragua "has almost exactly the same greyish-green colour as _Tillandsia
usneoides_, the so-called 'Vegetable Horsehair' common in the district....
If it could be shown that it frequented trees covered with that plant ...
there would be a curious case of mimicry between the sloth's hair and the
_Tillandsia_, and a good reason why so few of these Sloths are seen." The
stomach in the Sloths is complicated in structure, with several chambers;
one of these gives off a long crescent-shaped caecum. The skull of the
Sloths agrees in a number of particulars with that of the Anteaters. {172}

[Illustration]

FIG. 98.--Skeleton of Three-toed Sloth. _Bradypus tridactylus._ (After de
Blainville.)

The zygoma is incomplete, though the part connected with the frontal has a
strong downward process like that found in _Diprotodon_ and some other
mammals. There is, moreover, a process from the squamosal, though it does
not reach the anterior part and thus {173} complete the arcade. The
premaxillaries are very small, and are usually lost in dried skulls.
Coupled with these points of likeness are some differences. The lower jaw,
for instance, has a well-marked coronoid process. The pterygoids do not
meet in the middle line. The teeth are five or four in each half of each
jaw. There is no trace of a second set.

A peculiarity of the Sloths is the enormous number of dorsal vertebrae.
There are twenty-three of these in _Choloepus hoffmanni_, but only fifteen
to seventeen in the Three-toed Sloth, _Bradypus_. As in other American
Edentates, the acromion joins the coracoid. This connexion occurs in both
the Two-toed and the Three-toed species. The limbs of these creatures are
very long, a concomitant of an arboreal life. The femur has no third
trochanter. The genus _Bradypus_, which by reason of the fact that it has
not lost the third toe on the manus seems to be more primitive than
_Choloepus_, shows another structural feature which does not bear out this
conclusion. The trapezoid and the os magnum of the carpus are united, while
in _Choloepus_ they are perfectly distinct bones.

The intestine has no caecum.

There are several species of Sloths. Eminently perfect though the
organisation of the Sloth in relation to its particular surroundings
appears to us, Buffon selected the animal as the very type of imperfection
in nature. "One more defect," he wrote, "they could not have existed."

FAM. 3. DASYPODIDAE.--The family Dasypodidae or Armadillos contains a
considerable number of genera. _Tatusia_, _Tolypeutes_, _Dasypus_,
_Xenurus_, _Priodon_,[109] and _Chlamydophorus_. They have all a more or
less rigid covering of bony plates imbedded in the skin, which are not in
the least comparable with the scales of the Manis. Save the Whales, in one
or two genera of which traces of a dermal armature exist, the Armadillos
are unique among existing mammals in this particular. The term "Edentate"
is especially inapplicable to the Armadillos; the genus _Priodon_ may have
more than forty teeth in each jaw; a total of ninety was found in one
specimen examined by Professor Kükenthal. In the tendency of the teeth to
multiply, we have another example of a state of affairs which characterises
so many Whales. Generally, however, seven to nine is the number of teeth in
each {174} half jaw, of which one is often implanted in the premaxilla. The
Armadillos show their alliance with the other American Edentates in the
points enumerated above. Their teeth specially ally them to the Sloths,
while the salivary and digestive organs generally are on the Anteater plan,
but present a less extreme development. There are, however, caeca, paired
as in birds, in the genera _Dasypus_ and _Chlamydophorus_. The others have
none. But there is a dilatation at the commencement of the large intestine,
which is not very different from the slightly-developed caeca of _Dasypus_.

There are certain peculiarities in the skeleton, which distinguish this
family.

[Illustration]

FIG. 99.--Skull of Armadillo. _Dasypus sexcinctus._ × 2/3. _ex.oc_,
Exoccipital; _fr_, frontal; _max_, maxilla; _nas_, nasal; _par_, parietal;
_peri_, periotic; _p.max_, premaxilla; _s.oc_, supraoccipital; _sq_,
squamosal; _ty_, tympanic. (From Parker and Haswell's _Zoology_.)

{175}

[Illustration]

[Illustration]

FIG. 100.--Bones of the right manus of the Hairy Armadillo. _Dasypus
villosus._ × 2/3. _c_, Cuneiform; _l_, lunar; _m_, magnum; _p_, pisiform;
_R_, radius; _s_, scaphoid; _td_, trapezoid; _tm_, trapezium; _u_,
unciform; _U_, ulna; _I-V_, digits. (From Flower's _Osteology_.)

FIG. 101.--Bones of the manus of the Great Armadillo. _Priodon giganteus._
× 1/3. _a_, An accessory carpal ossicle in front of the pisiform, which is
not seen in the figure. Other letters as in Fig. 100. (From Flower's
_Osteology_.)

The skull in the Armadillos presents a number of likenesses to the other
American Edentates.[110] The premaxillaries are small, but are larger in
_Dasypus_ than in _Tatusia_. On the other hand the lachrymals are larger in
the latter. The zygomatic arch is complete, but there is no downward
process as in the Sloths. In _Tatusia_ (but not in _Dasypus_) the "short
thick pterygoids add somewhat to the hard palate." This is clearly a
beginning or a remnant of the quite crocodilian character of the palate of
_Myrmecophaga_. In the cervical vertebrae we see the Whale-like character
of fusion between individual vertebrae; and also, as in the Whales, the
degree to which this fusion is carried out varies; two to four may be thus
united. The additional articular facets upon the dorsal vertebrae have been
already commented upon as a point of important likeness to other American
Edentates. The dorsal vertebrae are commonly eleven in number, the lumbar
being three. But in _Priodon_ the numbers are twelve and two respectively.
There are traces to be observed of the double-headed attachment of the ribs
to the sternum. The shoulder girdle of the Armadillos is somewhat diverse
in form in different genera; the acromion is always large, and is
remarkable in _Priodon_ for the fact that the humerus also articulates with
it, its extremity being recurved, and forming a socket for this purpose. As
in some other Edentates there is a second spine on the scapula behind the
first. The clavicle is strong. There is some variation in the form of the
manus. It is five-fingered in _Dasypus_; in _Tolypeutes_ the first digit
has vanished; on the other hand, in _Priodon_, the fifth has become
rudimentary {176} and the third enormously enlarged. This latter fact
recalls the arrangement characteristic of _Myrmecophaga_. The pelvis is
greatly attached by the ischium to the vertebral column. The femur has a
third trochanter.

The various forms of Armadillos are largely distinguished by the number of
movable thin bands of scutes lying between the large anterior and posterior
shields. Thus we have _Dasypus sexcinctus_, _Tolypeutes tricinctus_, etc.

[Illustration]

FIG. 102.--Pelvis and sacrum of Armadillo. _Dasypus sexcinctus._ _ac_,
Acetabulum; _il_, ilium; _isch_, ischium; _obt.for_, obturator-foramen;
_pect.tub_, pectineal tubercle; _pub_, pubis. (From Parker and Haswell's
_Zoology_.)

The little Pichi-chago (or, more correctly, Pichy-ciego), _Chlamydophorus_,
which only grows to about 5 inches in length, has no movable bands at all.
It is covered with a uniform series of plates, which, moreover, are not
discontinuous at the neck. It differs, too, from the prevailing
Armadillo-type by the absence of conspicuous external ears. In the anterior
part of the body the armature consists of little more than the horny
plates, which in other Armadillos overlie the bony dermal plates. In the
hinder region the bony plates are strong. In this animal, therefore, we
have the dermal armature reduced to a minimum; but it must be noticed that,
like the extinct Glyptodons, the armature is continuous and nowhere ringed.

The genus _Tolypeutes_, of which the best-known species is _T. tricinctus_,
the Apar (there are two other species in the genus), can roll itself up
into a ball like the Pill-Millipede (_Glomeris_), and, protected by its
armour, roll away from its enemies like the Arthropod under similar
circumstances. This mode of protection, be it observed, is also adopted by
the Pangolin and by the {177} Hedgehog. The genus has only three movable
bands. The tail is short, and is covered with large tubercles. This genus
is very markedly digitigrade when running.

[Illustration]

FIG. 103.--Three-banded Armadillo or Apar. _Tolypeutes tricinctus._ × ¼.

[Illustration]

FIG. 104.--Peludo Armadillo. _Dasypus sexcinctus._ × ¼. (After Vogt and
Specht.)

The Peludo, _Dasypus sexcinctus_, is, like other Armadillos, an omnivorous
creature, and appears to be particularly fond of carrion. It will burrow up
to a decaying carcase like the ground-beetles. {178} Mr. W. H. Hudson has
described the way in which this Armadillo will kill a snake by holding it
down and literally sawing the reptile in half by help of the sharp and
serrated edges of the carapace. _Dasypus_ has a very short tail, which is
shielded by distinct rings near the base.

_Tatusia novemcincta_ is a species with nine movable bands. The genus has
four teats; the ears are near together. There are no caeca and no azygos
lobe to the lung. A species apparently belonging to this genus, but
described under the generic names of _Cryptophractus_ and _Praopus_, is
remarkable for the thick covering of hair, not entirely wanting but usually
thin in other Armadillos. In this particular species the coat of hair is so
thick as to conceal the underlying plates of the carapace. The individual
hairs are stiff, and one inch and a half in length.[111]

The genus _Xenurus_ contains several species, the best known of which is
inaptly named _X. unicinctus_. As a matter of fact the characteristic
feature of the genus is the existence of twelve or thirteen movable plates
between the two ends of the body. _X. unicinctus_ has twelve dorsal and
three lumbar vertebrae. This Armadillo, known by the vernacular name of the
Cabassou, has one of the most modified hands that are found in the family.
The first two digits are slender and elongated; but are quite normal in the
number of their phalanges. In the remaining three digits the metacarpal is
short and broad, while the proximal phalanx is either suppressed altogether
or fused with the metacarpal, the middle phalanx is present but short,
while the third phalanx is very large indeed. As in _Dasypus_, but not as
in _Tatusia_, which is in so many other respects divergent from these
genera, the lungs have an azygos lobe. As a small point of difference,
tending to show an alliance between the genera _Xenurus_ and _Dasypus_ and
their difference from _Tatusia_, is the deeply-imbedded gall-bladder; this
sac is not nearly so deeply plunged into the hepatic tissue in _Tatusia_.
_Xenurus_ has no caecal dilatations. The brain "is intermediate in its form
and surface markings between _Dasypus_ and _Tolypeutes_." The small
intestine is nearly eighteen times the length of the large. But these
intestinal measurements are not of much avail in this group as marks of
affinity, since in three species of _Dasypus_ Garrod gives the following
widely-divergent lengths:--_D. villosus_, 11.5 feet and 1.25; _D. minutus_
{179} 5.1, with a large intestine of no less than 7 feet; _D. vellerosus_
4.3 and .66.

_Priodon_ is the giant of its race. This Armadillo may reach a length of 3
feet to the base of the tail. The tail is some 20 inches long. The large
number of teeth has been already noticed. There are twelve or thirteen
bands. Other points in the structure of this genus have already been
mentioned, and need not be recapitulated. This Armadillo feeds upon
termites and carrion.

_Scleropleura_ is unfortunately but imperfectly known. The single species,
named by Milne-Edwards[112] _S. bruneti_, is apparently a very rare
inhabitant of Brazil. It is known by a single skin, which was tanned by the
hunter who obtained it. Thus the hair, if any, has dropped out. The plates
in the skin are deficient along the back and even upon the top of the head,
and are barely represented upon the tail posteriorly. The ears are small
and distant from each other. The tail is longish, about one-third of the
length of the body. The total length of the creature including the tail is
rather more than a foot and a half. The hunter who obtained it regarded it
as a hybrid between an Armadillo and an Anteater.

EXTINCT XENARTHRA.--There are a good many extinct forms of Armadillo, apart
of course from the Glyptodons. _Peltephilus_ is referred to later (p. 186).
_Dasypus_ was represented by a large form, 6 feet long, with a skull of one
foot in length. The genus _Eutatus_ was also large. The carapace was formed
of thirty-three distinct bands, of which the last twelve are soldered
together, but not fused into a shield as in _Dasypus_, etc.

An extinct group of American Edentates, termed the GRAVIGRADA,[113] are
somewhat intermediate between the Sloths and the Anteaters. A number of the
genera are well known from complete skeletons.

One of the typical forms of this group is _Mylodon_, which, together with
its immediate allies, is often placed in a separate family, MYLODONTIDAE.

_Mylodon_ itself was a large creature, as big as a Rhinoceros. It was
covered externally by armour in the skin, which did not form a massive
armature as in the Glyptodonts, but was in the {180} form of scattered
plates, small and not fused together. The general aspect of the skull is
decidedly Sloth-like. As in that animal, the malar bone is bifid
posteriorly, and between the bifurcation is embraced the process of the
squamosal. This latter is thus more developed than in the Sloth, but there
is no actual union between it and the malar. The premaxilla is small. The
lower jaw has both coronoid and ascending processes, and is massive. There
are five teeth on each side above, and four on each side below, as in the
Sloths. There are the normal seven cervical vertebrae and sixteen dorsals.
The limbs are not long and slender,but short and strong, the animal having
been terrestrial. The fore-feet were five-toed, of which the three inner
toes had claws. The hind-feet were only four-toed, and the two inner only
were clawed.

[Illustration]

FIG. 105.--_Mylodon robustus._ (Restoration, after Owen.)

_Scelidotherium_ is a genus which is a trifle smaller than the last. It has
only four properly-developed toes in the fore-foot, the thumb being
rudimentary; of these, the first two bear claws. The hind-feet are also
four-toed. Like _Mylodon_, _Scelidotherium_ is a Pleistocene genus.

_Glossotherium_ has a skull very much like the last two genera; but it is
remarkable for the fact that the nostrils instead of being unprotected with
bone anteriorly are there closed by a plate of bone formed by the
well-developed premaxillae, the nostrils appearing at the sides, and giving
the skull a curious likeness to that of a Chelonian. From a series of
recent and most important observations it appears to be clear that this
genus has survived into quite modern times.[114]

{181}

The well-known naturalist of La Plata, Señor Moreno, engaged in studies
connected with the political boundary line between Chili and the Argentine,
had occasion to visit Consuelo Cove on Last Hope Inlet in Patagonia.
Hanging from a tree he noticed a piece of dried skin, which at once struck
him as looking more like the remains of a Mylodon than of any living
animal. The inhabitants regarded this piece of skin as a great curiosity,
but were of opinion that it was the hide of a cow encrusted with pebbles!
This fragment from a bygone age was originally described by Professor
Ameghino, who had apparently seen some of the bonelets imbedded in it, as
_Neomylodon listai_, "a living representative of the ancient Gravigrade
Edentates of Argentina." That this piece of skin is of quite recent date
seems to be proved by a number of considerations. In the first place it is
covered by long hair of a light yellowish-brown colour; it does not seem
likely that hair would preserve its character for geological epochs. The
nearest corresponding case is that of the remains of Moas in New Zealand,
whose feathers, dried skin, and tendons are known. Now the Moa was
unquestionably contemporaneous with man, as abundant surviving legends
prove, and indeed it cannot have been long extinct. Still, hair is a
resisting structure, and in a dry cave, with no possibility of irruptions
of floods, might retain its characters for long periods. The evidence,
however, of more recent date is stronger than this. The skin shows patches
of reddish colour, suggestive of course of blood-stains. A small piece of
the outside of the skin at the cut edge, which presented the appearance of
freshly or comparatively freshly dried fluid, was submitted to a chemical
examination and shown to be serum! Dr. Lönnberg examined chemically a bit
of the skin itself and found in it, after boiling, glue, "which proves that
the collagen and gelatinous substances are perfectly preserved." After this
it seems impossible to suppose that the skin can be of any very great age;
for bacteria would have finished their work upon the serum and gelatine
long ago. Combined with the fresh appearance of the skin is the very fresh
appearance of the skull. In fact it is impossible to believe that the
animal was not alive quite a few years since, relatively speaking. It is
admitted that this animal was contemporaneous with man. There are actually
legends of a creature which may have been this _Glossotherium_. "Ancient
chroniclers inform us that the indigenous inhabitants recorded the
existence of a {182} strange, huge, ugly monster, which had its abode in
the Cordillera to the south of latitude 37. The Tehuelches and the
Gennakens have mentioned similar animals to me, of whose existence their
ancestors had transmitted the remembrance; and in the neighbourhood of Rio
Negro, the aged Cacique Sinchel, in 1875, pointed out to me a cave, the
supposed lair of one of these monsters, called 'Ellengassen'; but I must
add that none of the many Indians with whom I have conversed in Patagonia
have ever referred to the actual existence of animals to which we can
attribute the skin in question."

A rude painting in a cavern, in red ochre, seems to Dr. Moreno (whose words
we have just quoted) to be somewhat suggestive of a _Glyptodon_. There are
some reasons for believing that this quadruped was kept by man as a
domestic creature. In the cave are two walls of rough pieces of stone which
seem to have dropped down owing to the wearing away of the roof; they also
seem to have been loosely piled together to form two walls, within which
enclosure an imperfect skull of the animal was found. This skull shows
clearly that the so-called "_Neomylodon_" must be referred to
_Glossotherium_ or _Grypotherium_, as it is sometimes termed. This skull is
perforated on the roof in such a way as could only have been effected (in
the opinion of experts) by a weapon in the hand of a man. A hole in the
skin has been even compared to a bullet-wound. But this it is perhaps
unnecessary to discuss. The skin of _Glossotherium_ is, like that of other
extinct "Ground-sloths" (_e.g. Mylodon_), filled with small and irregular
ossicles. But in _Mylodon_, the sculptured appearance of the dermal
ossicles appears to indicate that they reached the surface of the body and
were covered by epidermis alone, which is not the case with the animal now
under consideration. The microscopic characters of the ossicles, too, show
differences in the two. _Glossotherium_ being "precisely intermediate
between _Mylodon_ and the existing Armadillo (_Dasypus_)." Now
_Glossotherium_ and _Mylodon_ are regarded as forms which lie between the
existing Anteaters and the Sloths of the same part of the world. We have
already pointed out the facts of structure which lead to this conclusion.
It might therefore be reasonably surmised that the hair of _Glossotherium_
would be also intermediate, or at least like that of one of the two genera
_Myrmecophaga_ and _Bradypus_. But microscopical investigation has {183}
negatived this supposition. It has shown that the Armadillos are in this
matter the nearest relatives of _Glossotherium_. This result is important
as tending further to confirm the close interrelationship of all the
American Edentates as contrasted with the Old-World forms--a matter which
has already been emphasised. It is suggested, however, that the absence of
under fur, which is so well developed in the Sloth, and the difference
shown in transverse sections from the hair of _Myrmecophaga_, may be
explained by difference in habitat. _Glossotherium_ lived under conditions
similar to those under which the Armadillos live to-day. Thus the outer
covering of the body became alike in the two cases, the same needs
supervening in both genera.

_Lestodon_ is another allied genus, which seems to possess canines. At any
rate, in front of the four molars, and separated from them by a diastema,
is a smallish, somewhat canine-like tooth, in both jaws.

_Megalonyx_ and its allies are sometimes placed in a distinct family,
MEGALONYCHIDAE. _Megalonyx_ itself had a skull very like that of
_Bradypus_, being shorter and not so elongated as in the Mylodontidae.
There is a strong tusk anteriorly, which is separated by a considerable
space from the three molars lying behind it. Both pairs of limbs seem to
have possessed five toes. This is a North American genus. It differs from
the bulk of the American Edentates in having a complete jugal arch.

_Megatherium_ is the type of yet a third family, MEGATHERIIDAE, of the
Gravigrade Edentates. This creature is familiar from the many restorations
which have been built up, and from its huge bulk, little short of that of
an elephant. The skull, which is small for the size of the creature, has a
complete jugal arch, from the middle of which depends a downward process as
in other allied forms. The teeth grow to an extraordinary depth, and there
are five of them in the upper and four in the lower jaw--on each side of
course. The fore-limbs of the _Megatherium_ are very much more slender than
the enormously bulky hind-limbs, upon which and the equally massive tail
the animal seems to have supported itself while tearing down branches of
trees, upon whose leaves it fed. In the scapula the acromion joins the
coracoid as in _Bradypus_; the clavicle is large. The fore-limb is
four-toed, and the hind-limb three-toed. The latter has but one clawed
digit (the third, _i.e._ the inner). {184} On the manus, the three inner
digits have powerful claws. This animal, too, was Pleistocene in time. The
Megatheriidae had, however, small as well as gigantic forms.

The genus _Zamicrus_ had a skull no bigger than that of a Sloth, while
_Nothrotherium_ was also a comparatively small creature; the teeth of the
latter genus are reduced to 4/3.

The extinct group of the GLYPTODONTIDAE comprises large creatures with a
dense covering of bony scutes which are arranged in a tesselated fashion,
and thus form an immobile armature of immense strength. In correspondence
with this massive carapace the dorsal vertebrae have fused together, and
the lumbar vertebrae form a series ankylosed to each other and to the
following sacrals. These creatures are all South American.

[Illustration]

FIG. 106.--_Glyptodon clavipes._ × 1/12. (After Owen.)

_Glyptodon_, the genus which gives its name to the family, is known from
numerous remains in South America, and also from so far north as Texas and
Mexico. It grew to be as long as 16 or 17 feet. In the skull there is an
exceedingly long downward process of the zygomatic arch, as in Sloths, the
arch itself being complete. The process extends so far down as to reach a
point about on a level with the middle of the lower jaw. The nasals are
short or rudimentary. As in _Myrmecophaga_, the pterygoids enter into the
formation of the bony palate. The lower jaw has a spout-shaped extremity,
and, behind, it rises into an enormous vertical branch as high as the front
part of the jaw is long. There are eight teeth in each half of each jaw. As
in {185} some Armadillos, the cervical vertebrae are at least partly fused.
The atlas is free, but the rest, or at any rate five of them, are united.
The last cervical is sometimes fused with the succeeding dorsals; the
latter are twelve in number, and are fused together so far as concerns
their centra and neural processes. The succeeding region of the vertebral
column includes seven to nine lumbars, which are fused with the eight
sacrals; in this region the neural processes are high, and there is thus
produced a strong and lofty ridge along the back, which forms a powerful
support for the carapace. The fore-limbs are shorter than the hind-limbs,
which latter are attached to an unusually massive pelvis. The claws of the
limbs are blunt and almost hoof-like.

The heavy carapace consists of sculptured, five or six-sided plates, which
have no particular arrangement in the middle, but towards the margins show
indications of an arrangement in transverse rows. The moderately long tail
is also encircled by bony skin-plates which are thorny above, or at least
provided each with a blunt upstanding process. It appears that outside this
bony system of scutes were horny epidermic scales, corresponding exactly
with the tesserae which they cover. There are apparently a good many
species of _Glyptodon_.

In the allied genus _Panochthus_ the tail is rather longer, and the bony
rings which surround it, instead of being all movable as in _Glyptodon_,
are at first so, but later, _i.e._ towards the end of the tail, become
welded into a single and massive piece. Both feet are here four-toed, while
in _Glyptodon_ the hind-feet are five-toed and the fore-feet four-toed.

_Daedicurus_ shows a further specialisation, in that the feet have three
and four digits respectively. The orbit too shows a specialisation in being
separated from the temporal fossa. The descending process of the zygomatic
arch is not so extraordinarily exaggerated as it is in _Glyptodon_. It has
the same terminal tube of osseous scutes upon the tail. This creature seems
to have reached a length of about twelve feet.

_Propalaeohoplophorus_ is, unlike the great Armadillos that we have
hitherto dealt with, a small animal, not exceeding 2 feet or so in length
of carapace. A small alveolus on each side of the premaxillae seems to
suggest the former presence of an incisor tooth; and it seems that the
animal possesses both true molars and premolars; for the first four of the
eight teeth are much {186} simpler in structure than those which follow.
The dorsal vertebrae again are not fused together; the hind-limbs are
five-toed. All the plates of the carapace are arranged in definite
transverse rows; it has been observed, too, that some of the anterior
scutes overlap like those of the Armadillos, to which this animal possesses
further likenesses in the exclusion of the maxillae from the border of the
nostril (a Glyptodont character), and the comparative feebleness of the
scutes.

A primitive genus also appears to be _Peltephilus_, which is perhaps rather
an Armadillo than a _Glyptodon_. However, it comes somewhat between the
two, like _Propalaeohoplophorus_, with which it may therefore be treated. A
most singular feature of this genus has been mentioned on p. 27 in
connexion with the skull in the Mammalia generally. That is the fact that a
portion of the squamosal surrounding the articular facet for the lower jaw
is separated by a suture from the rest of that bone, and is therefore
obviously suggestive of the quadrate in the lower Vertebrates. As in
certain Armadillos and Glyptodons, etc., the pterygoids appear in this
genus to have taken a share in the formation of the hard palate. The plates
of the carapace were movable, as is shown by the fact that they sometimes
slightly overlap. In view of the possible origin of the Edentates from
lowly-organised Mammalia, it is noteworthy that the humerus has been
especially compared to that of the Monotreme. _Peltephilus_ differs from
other Armadillos in having teeth in the front of the jaws. The total number
of teeth is twenty-eight, _i.e._ seven in each half of each jaw.

SUB-ORDER 2. NOMARTHRA.

As already explained, the Old-World Edentates differ from the New-World
forms in having normal dorsal vertebrae, that is to say, without additional
zygapophyses. That negative feature, however, though combined with the
positive fact that both the Old-World forms feed upon ants, is hardly
sufficient to outweigh the many structural differences which distinguish
the Orycteropodidae from the Manidae; which will be placed therefore in
different groups. To that containing the Aard Vark, the name TUBULIDENTATA
may be applied. {187}

This group contains but one family, the ORYCTEROPODIDAE, of which there is
but a single genus.

The Aard Vark (earth-pig), genus _Orycteropus_, is characterised by its
heavy build, the body being covered by rather coarse and not very abundant
hair; the snout is long and pig-like, with round nostrils at its end; the
ears are long, erect, and pointed; the tail is very thick at first, so that
it has been aptly described as "a tapering of the body to a point." The
fore-limbs are four-toed, the hind five-toed.

[Illustration]

FIG. 107.--Aard Vark, or Cape Anteater. _Orycteropus capensis._ × 1/16.

In the skull there is a complete though slender zygoma; the premaxillaries,
though small, are not so rudimentary as in the American Edentates. The
annular tympanic is not ankylosed to the surrounding bones, a character
found in other low mammals. Contrary to what is found in _Manis_,
_Orycteropus_ has a huge lachrymal. There are thirteen dorsal and seven
lumbar vertebrae. The clavicle is well developed. _Orycteropus_ is peculiar
among Edentates in that the ischia do not unite with the vertebral column.
The femur has a third trochanter.

As mentioned on p. 162, the Aard Vark is diphyodont like normal mammals.
The permanent teeth consist of five molars and premolars on each side of
each jaw; the first two of these are premolars, and are simpler in their
form than the succeeding two teeth, which are partly divided by a median
furrow into two halves. These teeth are also peculiar in that they consist
entirely of vaso-dentine. They have been compared in minute structure to
those of the Ray _Myliobates_. According to Mr. Oldfield {188} Thomas[115]
there are seven milk teeth on each side of the upper jaw (limited to the
maxillae, and thus not incisors). An eighth tooth was discovered on one
side of one of the specimens examined by Thomas. In the lower jaw there are
only four milk teeth on each side. It is interesting to note that the
histological structure of these milk teeth agrees with that of the
permanent teeth. There are two species of this genus found in Africa: the
southern, _O. capensis_, is more hairy than the northern, _O. aethiopicus_.
_O. gaudryi_ is a Pliocene species from the Island of Samos and from
Persia, described by Dr. Forsyth Major and Dr. Andrews.[116] It closely
resembles the existing _O. aethiopicus_.

[Illustration]

FIG. 108.--Section of lower jaw with the teeth of _Orycteropus_. × 2.
(After Owen.)

Of the Scaly Anteaters, Group SQUAMATA or MANIDAE, there is really but one
genus, though _Phatagin_, _Pholidotus_, _Smutsia_, and _Pangolin_ have been
used to distinguish various forms. The genus _Manis_ is African and
Oriental in range. Dr. Jentink, who has lately revised the species, allows
seven.[117] The external form of these animals is fairly well known, the
remarkable scales distinguishing the Pangolins from other animals. Between
the scales lie hairs, which seem to be absent in the adults of the African
species, though present in the young, thus affording a convenient method of
distinguishing the Ethiopian from the Oriental forms. The scales have been
compared to agglutinated hairs. That they are not "merely mimetic of the
Lizards' scales" is held by Weber,[118] who compares them directly with
those {189} structures, as he does the scales of other mammals, such as
those upon the tail of _Anomalurus_, etc. This, however, is not a universal
opinion. It is true that these scales occur chiefly in the lower forms of
mammals such as those under consideration, Marsupials, Rodents, and
Insectivores; but the fact that the hairs are developed before the scales
shows, or seems to show, that the former are the older structures, and to
lead to the inference that the scales of mammals are new structures. The
scattered hairs of the Pangolin have no sebaceous glands excepting on the
snout. This, again, looks as if they were degenerate structures, and
emphasises the non-archaic character of the scales. These animals have no
trace of teeth except possibly some slight epithelial thickenings which
have been interpreted as a last remnant; the tongue is suited for the
capture of ants, and is therefore much like that of the not nearly-related
American Anteaters. The stomach is of simple form; it is characterised by a
large gland, which suggests that of the Koala (see p. 144); the intestine
has no caecum. Retia mirabilia occur on the limb arteries. The placenta is
non-deciduate and diffuse; it is specially compared by Weber with that of
the Horse. Considering the many adaptive resemblances between this genus
and the American Anteaters, especially in the mouth cavity, it is
remarkable that in _Manis_ the pterygoids are not joined as they are in
_Myrmecophaga_. In spite of statements to the contrary, it appears that
there is sometimes a distinct lachrymal.

A remarkable feature in the skeleton of _Manis_ is the singular sternum.
The xiphoid cartilage is extraordinarily elongated into thin strips, which
reach the pelvis and return. This state of affairs is to be found in the
African species only. This structure is not comparable, as it has been said
to be, with abdominal ribs such as those of the reptile _Hatteria_.

These animals are mainly anteaters. The Japanese have a curious legend as
to the method adopted for the capture of ants, which is related by Dr.
Jentink in his monograph of the genus. The Manis "erects his scales and
feigns to be dead; the ants creep between the erected scales, after which
the anteater again closes its scales and enters the water; he now again
erects the scales, the ants are set floating, and are then swallowed by the
anteaters"! The same story is related by Mr. Stanley Flower on the
authority of the Malays.

Though it seems clear that the likenesses which _Manis_ shows {190} to the
Anteaters of the New World are chiefly adaptive and have nothing to do with
real affinity, being merely an expression of a similar mode of life, it is
curious to note that here and there we do find certain resemblances which
do not seem to be susceptible of the latter explanation. The jugal bone,
absent in _Manis_, is small in _Myrmecophaga_; the clavicle is absent and
again small or rudimentary in the Anteaters; it is large in other
Edentates. The third trochanter is absent, as in _Myrmecophaga_ (and the
Sloths). There are many scales on the body; in _Myrmecophaga_ there are
traces of these structures on the tail, as also in _Tamandua_. In the
features mentioned, the Myrmecophagidae differ from either or from both of
the two other American families (_i.e._ Dasypodidae, Bradypodidae) and
agree with _Manis_. The facts are not a little remarkable.

[Illustration]

FIG. 109.--Manis. _Manis gigantea._ × 1/12.

ORDER III. GANODONTA.[119]

Allied to the Edentata, and apparently representing the ancestral forms
from which they, at any rate the Xenarthra were derived, is the order of
the Ganodonta. Of this order a number of genera are now known, which can be
ranged in a series which more and more approaches the Edentata as we pass
from the older to the newer forms. This interesting and transitional series
will be made manifest by a description of the characters of the various
genera taken in their proper {191} chronological order. The following
genera are included by Wortman in his family STYLINODONTIDAE.

The earliest type of the Ganodonta is the genus _Hemiganus_, with but one
species, _H. otariidens_. This animal lived during the deposition of the
lowest Eocene strata, the Puerco beds of North America. It was about as big
as a fair-sized Dog, and had powerful jaws. There were at least two pairs
of incisors in the upper jaw, together with powerful canines and the full
premolar and molar formula. In the lower jaw the canines were also strong,
but the incisors are not certainly known to be more than two pairs. The
enamel upon the posterior surface of the canine is thin, and in the case of
the incisors the enamel seems to be limited to the anterior face. The lower
molars are quadritubercular. It is believed from the presence of a suture
on the upper surface of the premaxillary that the snout of the creature was
tubular. The cervical vertebrae, only known by their centra, are like those
of the Armadillos (and for the matter of that of the Whales) in the great
transverse as opposed to the antero-posterior diameter. The feet are
especially compared with those of the Ground Sloths. The single ungual
phalanx is marked by a large subungual process, which is pierced by a
considerable foramen. The tibia again is to be compared with that of the
Armadillos.

In the Upper Puerco (Torrejon) beds the remains of _Psittacotherium_ are
found. This genus, when first discovered, was referred to the Tillodontia
by some and to the Ungulates, the latter being a refuge for indeterminate
Eocene mammals, just as the "Multituberculata" is for similarly-placed
Secondary mammals. It is now known to be clearly a member of the order
Ganodonta. Wortman thinks that there is but one species, _P. multifragum_.
It seems to have had a general aspect much like that of _Hemiganus_--that
is judging from the skull--and was not very greatly different in size. The
facial portion of the skull is short, and the zygoma is deep. The
infra-orbital canal is double, a feature which crops up in the Sloth, and
has been mentioned in the later form of Ground Sloth, _Megalonyx_ (but it
must be remembered that the same characteristic is not unknown in Rodents).
The dentition is reduced as compared with that of _Hemiganus_, that is to
say, as far as concerns the molars and the incisors. There is but a single
pair of incisors in each jaw; the canines are strong; the premolar and
molar series seem to have been complete in the lower jaw, {192} but reduced
by one premolar at least in the upper jaw. It is very important to notice
that the incisors have enamel only on their anterior faces, and that the
same is the case with the canines, the slender layer present behind the
tooth in _Hemiganus_ having vanished in this later form. The tooth pattern
of the molars is like that of _Hemiganus_. The fore-limb is decidedly
Edentate-like; but it is the foot which presents the strongest likenesses
to that order. "If an anatomist," remarks Dr. Wortman, "had no other part
of the skeleton than that of the foot to guide his judgment, and he should
fail to detect a most striking similarity between it and that of the
Edentata, especially the Ground Sloths, he would not only lay himself open
to the criticism of being lacking in the ordinary powers of observation and
comparison, but would be suspected of placing the matter upon a basis other
than that established by such a method." It is not certain how many toes
upon the fore-limbs were possessed by _Psittacotherium_, but the close
resemblance to _Mylodon_ is indeed striking, the third digit being in both
forms the most pronounced. Some vertebrae of this Ganodont have been
discovered which do not show the complex articular arrangements of later
American Edentates. The sacrum, on the other hand, is very like that of the
Sloth, and there is a foreshadowing of the attachment of the ilia to the
sacrum by co-ossification which is met with in later Edentates. A still
later type is the genus _Calamodon_, which has been shown to occur in
Europe as well as in America. _C. simplex_ was a larger beast than either
of the genera that have already been treated of, thus affording another
example of the increase in size of later as compared with earlier members
of the same group, so pronounced among the Ungulata. The lower jaw has the
same massive structure that characterises that bone in _Hemiganus_ and
_Psittacotherium_. There is but one incisor, but the premolar and molar
series are complete. The canine is Rodent-like in appearance, being
imbedded throughout the greater part of the lower jaw; it evidently grew
from a persistent pulp. It is enamelled upon the anterior face only. The
premolar and molar teeth are in this genus commencing to lose their enamel,
which is distributed in the form of vertical bands, leaving interspaces
which are not covered by enamel. These teeth, moreover, are decidedly
hypselodont, more decidedly so than in _Psittacotherium_; they are, when
unworn, quadricuspidate, with accessory cusps; when more worn, the teeth
{193} are double-ridged, and that transversely to the long axis of the jaw;
finally, the much-worn teeth have flattish crowns more or less surrounded
by a ring of enamel.

A still later form, coming from the Lower and Middle Eocene strata, is the
genus _Stylinodon_. _S. cylindrifer_, which is the more archaic of the two
described species, is only known from a single molar, fragments of a
canine, and "some inconsiderable pieces of the skull." The molar is
interesting on account of the fact that the enamel is still further
reduced; it is represented only by narrow vertical strips, which are much
narrower than those of older forms of Ganodonts. It is also hypselodont,
and has a persistent pulp. So, too, the canine which had a thick anterior
facing of enamel. The later species, _S. mirus_, is more fully known. The
teeth seem to have been much the same as in the last-described species; the
premolars and molars were seven in all in the lower jaw, and the canine was
imbedded in the bone for a long distance, as in _Calamodon_. The cervical
vertebrae have short centra as in _Hemiganus_. The clavicles were well
developed. The humerus possessed an entepicondylar foramen, and its head
displays the pyriform pattern so characteristic of later Edentates. The
foot is clearly like that of _Psittacotherium_.

In reviewing the series, therefore, we see a gradual diminution of the
incisors, a gradual loss of enamel on the teeth generally, and the
production of hypselodont teeth growing from persistent pulps; all of which
are features of the later Edentates. The progression is so gradual that the
forms enumerated and described seem to have been part of a continuous
series culminating in the Ground Sloths of later times. The other points of
similarity will be gathered from the facts given in the foregoing pages.

There is another family belonging to the Ganodonta whose position with
regard to the Edentata is not so clear. This is the family CONORYCTIDAE, of
which two genera are known. The earliest of these, from the Lower Puerco,
is _Onychodectes_. In _O. tissonensis_ the skull is long and narrow, thus
contrasting with that of the last family. The facial part is also long. The
lower jaw is much more slender. The molar formula was complete, but there
is some doubt as to the incisors. The molars are tritubercular.

The other known genus is _Conoryctes_. Its skull has a shorter {194} facial
portion, and is thus more like that of Stylinodontidae than that of
_Onychodectes_. The dental formula is known, and is complete save for the
loss of one incisor above and below, and one premolar above. The
relationship of these Ganodonts to any later forms is uncertain; but their
skeletal structure is as yet by no means fully known.

       *       *       *       *       *


{195}

CHAPTER IX

UNGULATA--CONDYLARTHRA--AMBLYPODA--ANCYLOPODA--TYPOTHERIA--TOXODONTIA--
  PROBOSCIDEA--HYRACOIDEA

ORDER IV. UNGULATA

The existing members of this order can be readily grouped into the
Hyracoidea, Proboscidea, Perissodactyla, and Artiodactyla, each of which
divisions has quite the value of an order, and all of which are sharply
marked off from each other. But as the discovery of so many fossil forms
has to a great extent rendered these demarcations less sharp, it is better
to regard all these groups as not more than sub-orders of a larger "Order"
Ungulata. Even when this conclusion has been necessarily arrived at from a
consideration of the more ancient groups of Ungulate animals, the
definition of such an order remains a difficult matter for the systematist.
For the earliest of these forms, more particularly the Ancylopoda, the
Amblypoda, and the Condylarthra, whose peculiarities will be dealt with at
length subsequently, are not by any means easily differentiated from the
primitive Carnivorous mammals of that date, the Creodonta; these latter,
moreover, fade into the Marsupials through the so-called Sparassodonta of
Professor Ameghino. To confine ourselves to the Ungulates, we may perhaps
define them as terrestrial animals with hoofs rather than claws or nails,
and chiefly, if not entirely, vegetarian in habit. The teeth are bunodont
or lophodont, the tendency to the production of the latter type being
always marked. The walk, although plantigrade in the older types, becomes
more and more digitigrade, except in such survivals from antiquity as
_Hyrax_. There is, too, as we pass from the ancient types to the modern, a
gradual perfection of the limbs as running {196} and not climbing or
grasping organs; the number of toes becomes reduced, and culminates twice
(in the horse and in the Litopterna) in one toe on each foot; at the same
time the ulna becomes rudimentary and fuses with the radius, and the fibula
in the hind-limb undergoes a like reduction. The clavicle is absent even in
some of the oldest types; its presence in _Typotherium_[120] is highly
remarkable. The tail too, an organ which is long in some of the early
forms, gets short in their modern derivatives.

[Illustration]

FIG. 110.--An early Ungulate. _Phenacodus primaevus._ × 1/12. (After
Osborn.)

[Illustration]

FIG. 111.--Series of metacarpals and metatarsals of Camelidae, to show
secular and progressive increase in size. From left to right the species
are _Protylopus petersoni_, _Poebrotherium labiatum_, _Gomphotherium
sternbergi_, _Procamelus occidentalis_. F, Fore-foot; H, hind-foot; III,
IV, third and fourth metapodials. (After Wortman.)

Coupled with the increasing perfection of the foot as an organ used merely
for the support of the body, certain interesting changes have taken place
in the arrangement with regard to each other of the several bonelets of the
wrist and ankle. It has been held by Cope and others that the truly
primitive disposition of these bones was that presented to us by certain
early types, such as _Meniscotherium_ or the existing elephant or _Hyrax_.
In these animals there is (see Fig. 112) a serial {197} arrangement of
these bones, the distal bones only, or very nearly only, articulating with
the corresponding bones in the upper series. In the modern types (cf. Fig.
113) there is, on the other hand, an interlocking, so that the bones of the
distal series articulate with two of those of the proximal series. By this
is produced, as it would appear, a much firmer foot, less liable to "give"
under pressure, and thus more fitted for an animal that runs. It is the
same principle as that adopted in the laying of bricks. The actual stress
and strain of impact has been held responsible for those changes. An
equally ingenious and possibly truer explanation of the undoubted facts has
lately been advanced by Mr. W. D. {198} Matthew.[121] He has pointed out
that in some ancient Ungulates the carpus is not serial but interlocking,
even in forms which belong to the earliest Eocene groups, such as the genus
_Protolambda_ among the Amblypoda. Now in the fore-foot of _Meniscotherium_
and the living _Hyrax_ there is a separate centrale which is wanting in the
greater number of Ungulates. The absorption, that is the practical dropping
out of this bone, would restore to an interlocking carpus the serial
arrangement; while on the other hand, by the fusion of this bone with the
scaphoid, the interlocking disposition would be maintained.

[Illustration]

FIG. 112.--Bones of the manus A, of the Indian Elephant, _Elephas indicus_.
× 1/8. B, of the Cape Hyrax, _Hyrax capensis_. × 1. _c_, Cuneiform; _cc_,
centrale; _l_, lunar; _m_, magnum; _p_, pisiform; _R_, radius; _td_,
trapezoid; _tm_, trapezium; _s_, scaphoid; _u_, unciform; _U_, ulna. (From
Flower's _Osteology_.)

[Illustration]

FIG. 113.--Bones of the manus A, of Rhinoceros, _Rhinoceros sumatrensis_. ×
1/5. B, of Pig, _Sus scrofa_. × 1/3. Letters as in Fig. 112. (From Flower's
_Osteology_.)

The gradual perfecting of the fore- and hind-limbs as running organs has
been put down to the advent of the grasses, and the formation of large
plains covered with this herbage. The same reason would also be in harmony
with the equally gradual change in the shape of the molar teeth, from a
tubercular form calculated for a mixed or even a carnivorous diet, to the
flatter crushing surfaces exhibited by the lophodont teeth of later
Ungulates. Strong {199} canines would in the same way cease to be useful,
and even become encumbrances to such grazing creatures; and their
disappearance is one of the salient features in the history of the
Ungulata, that is of the modern representatives of the order. The
extraordinary hypertrophy of these teeth in such a line as that of the
Amblypoda, which has left no descendants, was one of the reasons perhaps
for the decay of those great pachyderms of mid-Tertiary times; their
excessive armature became an encumbrance, since it was not accompanied by
improvements in other necessary directions. Some of the features of the
Tertiary Ungulates have, however, been dealt with in our general sketch of
the mammalian life during that epoch, and need not be again referred to
here. Of existing Ungulates there are no clear indications of the descent
of the Elephants or of the Hyracoidea. Their structure proclaims these two
divisions to be of ancient descent, and not to be modern twigs of the
Ungulate stem. As to the Perissodactyla and the Artiodactyla we cannot
bring them together nearer than in quite early Tertiary times. The order
Condylarthra seems to be the starting-point of both these sub-divisions.
_Euprotogonia_ has been considered to be an ancestor of the Perissodactyle
branch, and _Protogonodon_ or _Protoselene_ of the Artiodactyla. If this be
true, {200} the likenesses which _Titanotherium_ shows to the Artiodactyla
must be either purely superficial and secondary, or a cropping out of
ancient characters which had been dormant for many generations.

HORNS.--The Ungulata are the only order of mammals which possess horns; as
they are on the whole a more defenceless group than the Carnivora, it may
be that the horns are a counterpoise to the teeth and claws of the latter;
need for defence and for armature in the combats with their own kind for
the favours of the does has led to a different kind of protective and
aggressive mechanism. Horns as weapons are, however, particularly effective
in this group wherever they exist. A Ruminant is most frequently a large
and heavy animal without the agility and litheness of the Carnivore. It is
precisely to this sort of animal, where weight is an important
consideration, that horns are the most suitable weapons. This is further
shown by the fact that although the general term horn is used to describe
the weapons of the Ungulate mammals, there is more than one kind of
structure included under this general term; it is indeed probable that the
extreme terms in the series of horns have been independently acquired by
their possessors. There is but little in common between the horns of a
Giraffe and of a Rhinoceros. In the Rhinoceros we have one or two horns, in
the latter case one placed behind the other, which are purely epidermic
growths; they may indeed be regarded as matted masses of hair, borne, it is
true, upon a boss of bone, which however is not a separate structure. The
Giraffe supplies us with the simplest term in that series of horns which
are partly epidermal and partly bony. The paired horns of this animal have
often been contrasted with those of the Deer, for example; but there is no
fundamental difference between them. In the Giraffe a pair of bony
outgrowths, originally separate from the skull which bears them, but
ultimately ankylosed to it, are covered by a layer of entirely unmodified
skin. A distinction of undoubtedly practical importance is usually drawn
between the Hollow-horned Ruminants, _i.e._ Oxen, Goats and Antelopes, and
the Deer tribe. There is nevertheless no fundamental distinction. In the
Antelopes there is a core of bone, the "os cornu" as it has been termed,
which is covered by a horny layer, the horn proper, variously modified in
shape and size according to the genus or species. In the Deer there is the
{201} same os cornu, which may however be branched, but which is in the
same way covered by a layer of modified integument; this is known as the
"velvet"; it only lasts for a certain period, and is then torn off by the
exertions of the animal itself, leaving behind the bony core, which is
popularly termed the horn. It will be clear that here is only a difference
of comparative unimportance; the same essential features are present in
both groups of animals, but the modification of the epidermis has
progressed along different lines. Both can be referred back to the
primitive conditions seen in the paired horns of the Giraffe. Even the
difference, such as it is, is bridged over by the Antelope _Antilocapra_,
where the os cornu is bifid and the horn is periodically shed, as is the
velvet of the stag; but in the stag the bony part of the horn is also shed,
a state of affairs which has no parallel in the Hollow-horned Ruminants.
The great _Sivatherium_ may conceivably be an annectant form between the
two types of compound horns, _i.e._ those of the Antelope and those of the
Deer. This creature had two pairs of horns, of which, naturally, only the
bony cores remain; the hinder pair of these were branched. But although so
far they resemble the Deer's horns rather than the Antelope's, Dr. Murie
has thought that they were covered by a horny sheath and not by soft skin
as in the Deer. In any case these horns were apparently never shed, which
is a point of likeness with the Antelope and of difference from the Deer.
Apart therefore from the nature of the covering of the bony cores, there
are good grounds for looking upon them as intermediate between those of the
Deer and those of the Antelopes.

The horns of the Ruminants are frequently a secondary sexual character;
this is especially the case with the Deer. The Reindeer is, however, an
exception, both the stags and the does having horns. That they are
associated with the reproductive function is shown by their being shed
after the period of rut, the destruction of the velvet at that period, and
also by the effect upon the horns which any injury to the reproductive
glands produces. Some useful facts upon this latter head have been amassed
by Dr. G. H. Fowler,[122] who noticed in a series of stags, horns showing
various degrees of degeneration in the antlers produced by varying degrees
and periods of gelding. From the facts {202} here collected it is clear
that a direct effect is produced. If we are to regard horns as secondary
sexual appendages which have been subsequently handed on to the female by
heredity, we should expect to meet with examples of animals now horned in
both sexes, of which the earlier representatives had the horns confined to
one sex. This is most interestingly shown by the extinct and Miocene
Giraffe, _Samotherium_, of which the male alone had a pair of short horns,
while the skull of the female was entirely hornless; the modern _Giraffa_,
as is well known, has horns in both sexes.

It is interesting to note that the existing Perissodactyles and
Artiodactyles are to be distinguished by their unpaired or paired horns.
But while there are no Artiodactyles with unpaired horns (save occasional
sports) the Perissodactyles have more than once tried, so to speak, paired
horns, which ultimately proved fatal to them. The Rhinoceros
_Diceratherium_ apparently inherited and improved upon the small paired
horns of _Aceratherium_, but it has left no descendant. The paired horned
Titanotheria offer another instance of the same apparent incompatibility
between the Perissodactyle structure and the persistence of paired horns.

SUB-ORDER 1. CONDYLARTHRA.

This group is characterised by the following assemblage of characters.
Extinct, often plantigrade Ungulates, with five-toed limbs. Bones of carpus
and tarsus not always interlocking, but sometimes lying above each other in
corresponding positions. The humerus has an entepicondylar foramen. Dental
formula quite complete; the molars brachyodont and bunodont. The premolars
are simpler than the molars. The canines are small. As with other early
types, the zygapophyses are flat and do not interlock. The astragalus is
like that of the Creodonta. This group was American and European in range,
the remains of its rather numerous genera being of Eocene time. The
best-known genus is _Phenacodus_, of which some account will be given
before discussing the, in many cases, more fragmentary remains of other
allied forms.

The genus _Phenacodus_ was first described so long ago as 1872, from a few
scattered teeth. Since then several nearly complete skeletons have been
obtained, and we are in full possession of {203} the details of its
osteology. It was not a large creature (see Fig. 110, p. 196), about 6 feet
in length, with a small head. The feet were more or less plantigrade, and
five-toed. The last phalanges of the toes show that they carried hoofs and
not claws; yet the fore-feet look a little as if they could be used as
grasping organs. The third digit of both hind- and fore-feet exceeds the
others, and thus a Perissodactyle-like foot characterised this Eocene
creature. The tail is exceedingly long, and must have reached the ground as
the animal walked. This is of course by no means an Ungulate character.
Still, in the totality of its organisation the animal was decidedly
Ungulate, though Professor Cope spoke of _Phenacodus_ as not merely an
ancestral Ungulate but as the parent form of Insectivores, Carnivores,
Lemurs, Monkeys, and Man himself! The scapula indeed is from its breadth
and oval contour rather like that of a Carnivore. The clavicles as in other
Ungulates are absent. The femur is Perissodactyle rather than Artiodactyle
in the presence of a third trochanter. The creature had fifteen pairs of
ribs and five or six lumbar vertebrae. The two bones of the leg which lie
below the femur are perfectly distinct and separate. A cast of the
brain-case shows that the cerebral hemispheres were smooth and small, the
cerebellum of course completely uncovered and nearly as large as the
cerebrum. The olfactory lobes were also large. The complete skeleton of
_Phenacodus_ has lately been excavated more fully from the enveloping
matrix by Professor Osborn,[123] and mounted in what is regarded as the
natural position of the beast. It appears that though five-toed it went
upon the three middle toes only, and furthermore that of these the middle
one was the more prevailing, so that _Phenacodus_ was distinctly
"Perissodactyle," at least in habit. Moreover its "long hind-quarters, the
long powerful tail ... are reminiscent of Creodont ancestry." The genus was
European and American in range.

_Meniscotherium_ ( = _Hyracops_[124]) comprises several forms of about the
size of a fox; they are both European and American in range. The teeth are
more distinctly Ungulate in form than those of _Phenacodus_, with a
[125]-shaped outer wall. The skull is described as possessing "indifferent,
primitive characters," permitting a comparison with those of Opossums,
Insectivores, and {204} Creodonta. It has, as in _Phenacodus_, no orbital
ring. The humerus resembles that of a Carnivore rather than that of an
Ungulate. The carpus and tarsus are serial. The fibula articulates with
both the calcaneum and the astragalus, which is not the case with
_Phenacodus_. It is suggested that these animals are ancestral forms of the
Chalicotheres. In the brain the hemispheres do not cover the cerebellum.

More primitive apparently than _Phenacodus_ was the less-known genus
_Euprotogonia_, or _Protogonia_[126] as it has been called. The best-known
species is _E. puercensis_, so called from its occurrence in the Puerco
beds of the American Eocene. It was a slender, long-limbed creature,
smaller than _Phenacodus_, with a long and heavy tail as in that animal.
Like _Phenacodus_ it was semiplantigrade, and shows more likenesses to the
Creodonta. The skull is only known by a part of the lower jaw with teeth,
and by the teeth of the upper jaw. The vertebrae are not entirely
preserved, but enough remain to show that the animal had a tail of 16 or 17
inches, which is a considerable length when compared to its height, about a
foot at the rump. In the fore-limb the most noteworthy point is that the
ulna has a convex posterior border as in the Creodonts, the same border in
_Phenacodus_ being concave. The humerus is slender, with less-marked
tuberosities. The fifth digit seems to have been less reduced. The
phalanges seem to have borne horny sheaths somewhat intermediate between
hoofs and claws. The pelvis is described as being, as is also that of
_Phenacodus_, rather like that of the Creodonta. The right hind-limb is
known in all its details. It appears that the bones are not serial but
interlocking; this, however, on the views with regard to the relations of
these two forms of tarsus mentioned on p. 198, does not militate against
regarding _Euprotogonia_ as the ancestor of the genus _Phenacodus_. The
third toe is the pre-eminent one, the animal thus being Perissodactyle. The
lateral digits are larger than in _Phenacodus_, and the metatarsals and the
phalanges are slightly curved, which is again a Creodont character as
compared to the perfectly straight corresponding bones of _Phenacodus_. It
seems evident that this animal is to be looked upon as a more ancient type
than _Phenacodus_, even if not as its actual ancestor.

Another group of the Condylarthra contains the genus _Pertipychus_ and some
others. _Periptychus_ has the full dentition {205} of forty-four teeth, the
molars being of course bunodont, with the three chief tubercles most
developed. The bones of the tarsus interlock and are not serial, as they
are in many other members of the Condylarthra. The astragalus has a shorter
neck than in _Meniscotherium_, for example. It has in this a likeness to
the same bone in the Amblypoda, to the primitive members of which, such as
_Pantolambda_, this animal bears much resemblance. "Astragali and many
skeletal bones of _Periptychus rhabdodon_ and _Pantolambda bathmodon_ are
almost indistinguishable," observes Mr. Matthew. The fore-feet of this
genus are unknown, but it would seem that it was plantigrade from the
evidence of the hind-feet. There are several species of the genus.

Possibly, but not at all certainly, the Mioclaenidae, with the genera
_Mioclaenus_ and _Protoselene_, are to be referred to this same order of
primitive Ungulates. It is only necessary to mention them here, because
they show very clearly the primitive form of dentition of these early
Eocene mammals. The teeth are quite complete and unbroken by a diastema.
The canines are but little pronounced. The molars are not strictly
tritubercular, but have a prevailing trituberculy. The nature of the feet
is not known. Since the genus _Protoselene_, as its name denotes, shows an
indication of a commencing selenodonty, it has been suggested that this
group is the stock whence the Artiodactyles have been derived.

In any case, whether the particular comparisons that have been made as to
the relationship of various forms of Condylarthra are valid or not, it
seems to be plain that this group represents the earliest Ungulate stock,
but little differentiated from the contemporaneous Creodonts.

SUB-ORDER 2. AMBLYPODA.

This group of extinct mammals has the following principal
characteristics:--

They are large, semiplantigrade Ungulates, of heavy build and apparently
elephantine gait. The dentition is for the most part complete as in other
ancient groups, and the canines are in the later forms big tusks. The back
teeth are brachyodont and ridged (lophodont). Both radius and ulna in the
fore-limb, and tibia and fibula in the hind-limb, are well developed. The
bones {206} in the carpus are alternating in position. The toes are five in
both feet, and are very short. There is a hint of commencing
"perissodactylism" in the fore-feet at any rate. The brain is small and the
hemispheres smooth.

The Amblypoda, or Amblydactyla, are so called on account of their short and
stumpy feet and toes. They were held by Professor Cope to be on the direct
line of ancestry of both Perissodactyles and Artiodactyles, a view which is
on the whole not accepted at present.

[Illustration]

FIG. 114.--Skull of _Protolambda bathmodon_. × ¾. _e.a.m_, External
auditory meatus; _m_, mastoid; _m.f_, mastoid foramen. (After Osborn.)

As is the case with other groups, the Amblypoda commenced existence as a
sub-order with relatively small forms such as _Pantolambda_, the most
ancient type known, which is in many respects a transition between the
later forms and other groups of mammals such as the Creodonta.[127] The
race culminated and ended in the giant _Dinoceras_ and _Coryphodon_, and
spread into the Old World. In spite of their smooth and diminutive brain,
these mammals were able to hold their own and to multiply into many species
and genera; in this they were perhaps aided by their formidable tusks and
by the horns which many of them possessed. The teeth seem to imply an
omnivorous diet, which was quite possibly an additional advantage in the
struggle for existence. It does not seem to be necessary to divide off the
Dinoceratidae into a sub-order equivalent to the Coryphodontidae as was
done {207} by Professor Marsh; the numerous points in common possessed by
the members of both families forbid their separation more widely than as
families.

The earliest types of Amblypoda belong to the genus _Pantolambda_, of which
the species _P. bathmodon_ was about four feet in length. As restored it
seems to have had proportionately short fore- and hind-limbs, and it had a
long tail. It was apparently plantigrade, and would have had not a little
likeness to a carnivorous type. The skull has no air cavities, such as are
developed in the later types from the Lower Eocene, e.g. _Coryphodon_;
_Pantolambda_ is from the basal Eocene. The frontal bones show no trace of
the horns that are developed in subsequent forms; the nasals are
comparatively long; the zygomatic arch is slender. The molar teeth are in
the primitive form of trituberculy, and the premolars, as is so often the
case with primitive animals, are unlike the molars in form, being less
markedly selenodont. As to the vertebral column, the dorsal vertebrae
appear to have had short spines, which argues, as it does also in the case
of the larger and heavier _Coryphodon_, a feebleness in the development of
ligaments and muscles supporting and moving the head. The scapula seems to
have the same peculiar leaf-like form that it has in the later
_Coryphodon_.[128] This primitive type shows an entepicondylar foramen in
the humerus. It is interesting to observe that the posterior border of the
ulna is convex, as in the Creodonts, and in the early Condylarthrous form
_Euprotogonia_. In the subsequently-developed Amblypoda, as in the later
Condylarthra, that bone acquires a concave outer border. In the carpus the
os centrale is distinct. In the femur the third trochanter is well formed;
it gradually dies out in later Amblypoda. The fibula articulates with the
calcaneum. This species, according to Osborn, "typifies the hypothetical
Protungulate, being more primitive than either _Euprotogonia_ or
_Phenacodus_."[129]

[Illustration]

FIG. 115.--Skeleton of _Coryphodon radians_. × 1/10. (After Osborn.)

The genus _Coryphodon_ is known by a large number of species, of which the
first was discovered in this country, and was represented merely by a jaw
with some teeth. This was named by Sir R. Owen _C. eocaenus_, and was
dredged up from the bottom of the sea off the Essex coast. A second
specimen consisted of a single {209} canine tooth only, and was brought up
from a depth of 160 feet during the making of a well at Camberwell. More
abundant remains have since been found in North America.

This genus had a large head, and in some specimens traces of the "horn
cores," so marked in the related _Dinoceras_, are to be noticed. The skull
is broad behind and narrowed in front; the roofing bones show the cellular
spaces so characteristic of the Elephant. The jugal bone, however, is not,
as it is in the Elephant, placed in the middle of the somewhat massive
zygomatic arch. As in some other primitive Ungulates (e.g. _Phenacodus_)
there are twenty dorso-lumbar vertebrae, of which fifteen bore ribs.

The scapula seems to have possessed a peculiar leaf-like form, swelling in
the middle and ending almost in a point above. It has a well-marked spine,
and the acromion projects much. The fore- as well as the hind-feet are in a
state of transition between plantigradism and digitigradism. It was at one
time held that the animal was digitigrade as to the fore-feet and
plantigrade as to the hind-feet. Though, as has been pointed out, it is a
fact that the hind-feet are often on a different plane of evolution from
the fore-feet, it seems that this amount of difference does not
characterise any Ungulate, not excepting the genus now under consideration.

The toes are very spreading. The pelvic girdle is of great strength and
broadness. The femur, as in the Perissodactyles, has a well-developed third
trochanter; but whereas in this particular the hind-limb is Perissodactyle,
it is Artiodactyle in the fact that the tibia and the fibula articulate
with the astragalus and calcaneum. The ridged teeth have given the name to
the genus.

A curious feature in the structure of the genus are the slender spines of
the dorsal vertebrae, which contrast with the enormous ones of some other
Ungulates--more curious in this genus, which is of heavy build, than in the
lighter _Pantolambda_. The back of the animal is short, and the limbs are
very spreading, so that the gait was doubtless shuffling. The large head,
and short and heavy limbs and limb girdles added probably to its cumbrous
walk or trot. The canines are great tusks, and spread out on both sides of
the mouth.[130]

The late Professor Cope, in 1874, described the probable appearance of the
_Coryphodon_ in the following words:--"The general appearance of the
Coryphodons, as determined by the skeleton {210} probably resembled the
bears more than any living animals, with the important exception that in
their feet they were much like the elephant. To the general proportions of
the bears must be added the tail of medium length. Whether they were
covered with hair or not is of course uncertain. Of their nearest living
allies, the elephants, some were hairy and others naked.... The movements
of the Coryphodons doubtless resembled those of the elephant in its
shuffling and ambling gait, and may have been even more awkward from the
inflexibility of the ankle."

The most recent members of this sub-order come from the Middle Eocene beds,
and are chiefly referable to the genus _Dinoceras_, with which _Tinoceras_
and _Uintatherium_ are at least very nearly related, if not identical.
These creatures were of great size, larger than the earlier types which
have been considered. They show a certain superficial resemblance to the
Titanotheriidae, on account of the massive horn cores upon the skull. These
horn cores are large upon the maxillae and the parietals, and are paired;
on the nasals are smaller horns. The bones of the skull have air cavities.
The incisors of the upper jaw are absent; the canines are enormous tusks,
and the lower jaws are flanged downwards near the symphysis where these
tusks border them. Contrary to what is found in the older types, where the
position of the condyle of the lower jaw is normal, this prominence faces
backwards in the Dinocerata. The same shortness of the spines of the dorsal
vertebrae prevails in this group as in the other Amblypoda, though it is
perhaps hardly so marked. The scapula has not the peculiar acuminate form
that exists in _Coryphodon_, but is triangular and broad above. The limbs
are elephantine, in that the angle between the humerus and the femur
respectively, and the bones which follow, is not marked. The hind-limbs are
especially straight. The tail is short as compared with that of the
primitive Amblypoda. The Dinocerata are purely digitigrade. The
entepicondylar foramen has, as in the Coryphodonts, disappeared. The os
centrale of the carpus has become fused, and no longer exists as a separate
bone. The fibula no longer articulates with the calcaneum, but both that
bone and the ulna are well developed. The genus _Astrapotherium_ is placed
among the Amblypoda by some authorities.[131]

{211}

SUB-ORDER 3. ANCYLOPODA.

The history of the discovery of the members of this order is very
instructive as illustrating the dangers of laying too much classificatory
importance upon detached fragments of animals. So long ago as 1825 terminal
phalanges of a new creature were found in the Miocene of Eppelsheim, and
sent to Cuvier. Cuvier named them "Pangolin gigantesque," deeming them, on
account of their general form and cleft terminations, to pertain to the
Edentata. In the same bed some seven years later were found certain teeth
clearly of an Ungulate character, to which the generic name of
_Chalicotherium_ was applied. It was subsequently discovered that the teeth
and the claws belonged to the same animal, and, later, further remains
turned up which disclosed a creature having the anomalous composition of an
Ungulate with decisively Ungulate teeth, but with the feet to a large
extent like those of an unguiculate animal. The same confusion of
characters occurs also, it will be remembered, in the distinctly
Artiodactyle _Agriochoerus_ (see p. 331). Indeed the feet of the latter
when first discovered were erroneously, as it now appears, referred to the
present order of Ungulates under the name of _Artionyx_. It is probable
that the genus _Moropus_ of North America is a member of this group, and
that it is probably congeneric with a somewhat different type of Ancylopod
known as _Macrotherium_. It is also clear that _Anisodon_, _Schizotherium_,
and _Ancylotherium_, if not congeneric with either of the two recognised
genera, are at least very close to them.

_Chalicotherium_ has a skull which recalls that of some of the earlier
Ungulates; it has, however, no incisors at all, and no canines in the upper
jaw; this feature has led to the belief that the animal is related to the
Edentata, and that it is in fact a link between them and the Ungulata. The
molars, like those of the Perissodactyla, are of the buno-selenodont type.
It also agrees with that group (to which it has been approximated by
several writers) in the. tridactyl manus and pes, and in the characters of
the tarsus. But although tridactyl, the axis of the limb passes through the
fourth digit. _Chalicotherium_ is not mesaxonic, as are the
Perissodactyles. Moreover, it has no third {212} trochanter, and the
unguiculate claws have already been referred to. As to the latter, which
are short, it is not the end phalanx but the first which is retracted; thus
_Chalicotherium_ differs markedly from both Carnivorous and Edentate types;
for in the former it is the last phalanx which is retracted, while in the
Edentates the same phalanx is flexed downwards. The limbs of
_Chalicotherium_ are nearly of the same size, and the animal seems to have
been stout and quadrupedal.[132]

_Macrotherium_, like the last genus, seems to have been common to both New
and Old Worlds. It is to be distinguished by a number of characters. It is
supposed to have been "semi-arboreal and fossorial"; the fore-limbs are
much longer than the hind, the relative proportions of the radius and tibia
being 70 to 29. The ulna was distinct from the radius, whereas in
_Chalicotherium_ the two are coalesced, or nearly so. Young specimens
appear to possess a full set of incisors; whether this is the case or not
with _Chalicotherium_ is not known.[133]

_Homalodontotherium_ is sometimes placed in the group.

SUB-ORDER 4. TYPOTHERIA.

It is a little difficult to be confident that the Typotheria are rightly
referred to the Ungulata, since they contradict two important Ungulate
rules. They have clavicles, which are elsewhere missing, and the thumb
looks as if it were opposable.[134] An Ungulate is essentially a running
animal, and has no need of a grasping finger. Still Typotheria are placed
by most within the Ungulate series, though their undoubted likenesses to
other groups, especially to the Rodentia, are admitted, and indeed
emphasised. Cope places them definitely with the Toxodonts.

The Typotheria are an extinct group of smallish beasts, confined, like the
Toxodontia, to South America, a region which during the Tertiary period,
and into the Pleistocene, abounded with strange and varied types of
Ungulate animals.

The earlier forms of Typotheria may be exemplified by some {213} account of
the genus _Protypotherium_. This animal was of about the size of a _Hyrax_,
which indeed it resembles in several points of structure. The teeth have
the primitive number of forty-four, and they are close set, leaving no
diastema; the molars are rootless and grow persistently; they are simple
and Rodent-like in surface pattern. The shape of the lower jaw is like that
of _Hyrax_, being rounded in outline posteriorly; there is no projecting
angle as in the Rodents, and this remark applies to the Typotheria in
general. The aspect of the Rodent lower jaw is characteristically different
from that of _Hyrax_ and the forms under consideration.

Some other characters of these early forms of Typotheria can be gathered
from an inspection of other genera. In _Icochilus_ both hand and foot were
five-toed, and, as in ancient Ungulates generally, the bones of the wrist
and of the ankle are serially and not alternately arranged. Moreover, an os
centrale is present in the carpus. Both thumb and big toe were opposable.
The skull has a remarkably Rodent-like appearance, but the palate is not so
narrowed as in these animals.

In the more recent forms of Typotheria the dentition has become reduced.
The canines are lost, and as the incisors are reduced also, to one on each
side of the upper, and two on each side of the lower jaw, the likeness to a
Rodent skull is increased. There is also evidence of a modification from
the more primitive forms in the loss of one premolar or even more, in the
alternating bones of the carpus, in the disappearance of the centrale, and
in the loss of a toe upon the hind-foot. In these more recent forms the
fibula articulates with the astragalus instead of with the calcaneum.
Typotheria of these more recent forms may be illustrated by the typical
genus _Typotherium_. It has the reduced dental formula I 1/2 C 0/0 Pm 2/1
M 3/3; the molars are simple in pattern, and much like those of _Toxodon_.
The upper incisors are powerful and curved, but are surrounded by a layer
of enamel, which is not limited to the anterior face, as it practically is
in Rodents. The sacrum is composed of a large number of vertebrae--some
seven--a state of affairs which recalls the Edentata. The shoulder blade is
not Ungulate in form. It has a strong spine, with an acromion and a
well-developed metacromion. The terminal phalanges are enlarged and
hoof-like.

In the genus _Pachyrucos_ there are three premolars, otherwise {214} the
formula is the same as in _Typotherium_. The animal seems to have had nails
rather than hoofs. The thumb was opposable. The fibula is fused below with
the tibia, whereas in the last genus these two bones are quite separate
from each other.

SUB-ORDER 5. TOXODONTIA

The group Toxodontia,[135] like so many others, is exceedingly hard to
define. Nor are its limits any easier to mark out than many others of the
groups of Ungulates. It will be best perhaps to give an account of
_Toxodon_, and of a few types which seem to lie near it in the system, and
then to indicate how far they resemble or depart in structure from other
Ungulates. _Toxodon_ itself is known from complete skeletons. It lived in
Argentina during the "Pampean" period, which seems to be of the Pleistocene
age. A large number of species, however, have been described, some of which
seem to go farther back in time, and to have existed during the Miocene
period further south in Patagonia.

The size of this creature was about that of a large Rhinoceros; it has a
bulky body and a large head, which was borne low down, on account of the
bending downwards of the anterior vertebrae; in this aspect the figures of
the skeletons recall _Glyptodon_ and similar Edentates. The beast was
discovered by Darwin, and originally described by Owen. "During his (Mr.
Darwin's) sojourn in Banda Oriental," writes the Rev. H. Hutchinson,
"having heard of some 'giants' bones' at a farmhouse on the Sarandis, a
small stream entering the Rio Negro, he rode there, and purchased for the
sum of eighteenpence the skull which has been described by Sir R. Owen. The
people at the farm-house told Mr. Darwin that the remains were exposed by a
flood having washed down part of a bank of earth. When found, the head was
quite perfect, but the boys knocked the teeth out with stones, and then set
up the head as a mark to throw at." The whole of the Pampean area is a
valley of dry bones, and the remains of _Toxodon_ are abundant there. The
skull of _Toxodon_ is not unlike that of a horse in general aspect; but the
orbit is not separated from the temporal fossa. The premaxillae are
furnished above with a slight protuberance directed towards {215} the free
end of the nasals, which may be related to the presence of a short
proboscis. The zygomatic arch is strong and broad: the mandibles are
provided with a long symphysis. The dental formula is I 2/3 C (0-1)/1
Pm 4/(3-4) M 3/3. The teeth are prismatic and hypselodont, growing from
persistent pulps. The molar teeth are slightly arched in form, whence the
name of _Toxodon_, "bow teeth." The strong chisel-shaped incisors suggest
the Rodents and _Hyrax_. The cheek teeth, moreover, are by no means unlike
those of Rodents in their pattern. They are at any rate not at all like
those of existing Ungulates. The small size of the canine and of the first
premolar produces a diastema in the tooth series. The sacrum consists of
five vertebrae, and the ischium does not articulate with it.

The shoulder blade has a strong spine, but only a rudimentary acromion; nor
is the coracoid well developed. The radius crosses the ulna, as in the
Elephant; the whole fore-limb is shorter than the hind-limb, which must
have exaggerated the hang-dog expression of the creature when alive. The
elements of the carpus interlock in the modern fashion. Those of the
tarsus, however, are primitive in lying below each other without
alternation. The carpus has a centrale. The fibula articulates with the
calcaneum. The femur has no third trochanter. There are three toes to all
the limbs. It is clear that this assemblage of characters will not allow
the placing of _Toxodon_ in any living Ungulate order. If the middle toes
appear by their slight pre-eminence to approach the Perissodactyle form,
the peculiar surface contour of the molar teeth, letting alone the absence
of a third trochanter on the femur, will not permit this classification.

Allied to _Toxodon_ is the genus _Nesodon_. It was so named from an "island
lobe" on the inner side of the upper molars. This creature, smaller than
_Toxodon_, also differs from it in the fact that the dentition is complete,
and in the pattern of the molars, which is rather more complex. There is
still the slight projection upon the premaxillary bones, but the nostril is
directed more forwards than in _Toxodon_. The zygoma, too, is massive. The
second pair of incisors in the upper jaw and the outer (third) pair in the
lower jaw form biggish tusks in the adult. These and the molar teeth are,
however, finally rooted, and do not grow, as in _Toxodon_, from persistent
pulps. The genus is from the older Tertiary of Patagonia. Five or six
species have been described. Some are as large as a Rhinoceros, others as
small as a Sheep. {216}

There is no doubt about the close alliance of the two genera just referred
to. It is more doubtful whether _Homalodontotherium_ and its allies should
be placed, as they often are, in the neighbourhood of the Toxodonts.
_Homalodontotherium_ owes its name to its even row of teeth without a
diastema. It was a creature of equally large size with _Toxodon_, and also
came from the Tertiary strata of Patagonia. The teeth are the typical
forty-four, and the molars like those of a Rhinoceros; they are, however,
brachyodont and not hypselodont as in _Toxodon_. This genus, however, shows
an important difference from the Rhinocerotidae and from the other
Toxodontia in the fact that it was five-toed, and that the bones of the
carpus and tarsus are set in relation to each other in the linear serial
fashion.

Undoubtedly a near relative of _Homalodontotherium_ is _Astrapotherium_.
This creature was of equal bulk, and was also Patagonian in range. The
teeth are reduced in number, but the animal was provided, like a Wild Boar,
with great tusks, which were, however, formed by the incisors. This animal
is very imperfectly known; it is the form of the molars and the large size
of the incisors which have led to its association with the Toxodontia. As
to the resemblance of the teeth of this genus and of _Homalodontotherium_
to those of _Rhinoceros_, it is difficult to regard it as evidence of near
affinity. The likeness is probably to be looked upon as a case of
parallelism in development. Exactly the same explanation is possibly to be
given to the likeness which the teeth of _Toxodon_ and _Nesodon_ show to
Rodents, or even to Edentates. As to their affinities Zittel observes:--

"The entirety of their osteological characters argues for the Toxodon a
separate position in the neighbourhood of the Perissodactyla, Proboscidea,
Typotheria, and Hyracoidea. The relations to the Rodentia rest mainly upon
the converging development of the teeth, not upon true relationship."

SUB-ORDER 6. PROBOSCIDEA.

Large vegetable-feeding animals, usually scantily covered with hair, and
with the nostrils and upper lip drawn out into a long proboscis. Digits
five on both limbs. Femur and humerus not bent upon lower leg and fore-arm
in a position of rest. Skull {217} with abundant air cavities in the
roofing and other bones. The incisors are developed into long tusks, which
exist in the upper jaw alone, in the lower jaw alone, or in both jaws.
There are no canines. The molars are lophodont. The clavicle is absent. The
femur has no third trochanter. The bones of the carpus are serially
arranged and do not interlock. The stomach is simple. The brain has much
convoluted cerebral hemispheres, but the cerebellum is completely uncovered
by them. The intestine is provided with a wide caecum. The testes are
abdominal. The teats are pectoral in position. The placenta is
non-deciduate and zonary. There are two venae cavae superiores.

The position of the limbs in the Elephant tribe is unique among living
animals: their straightness that is to say, and the absence or very slight
development of angulation at the joints of the limb bones. This same
feature has been observed in the extinct Dinocerata and in the
Titanotheria. It must not, however, be assumed from the resemblance to
these ancient forms that there is much affinity between them and the
Proboscidea, or that the latter have retained an ancient feature of
organisation. The oldest Ungulates for the most part, and the Creodonts to
which they are undoubtedly related, have much bent limbs. It must be
considered, therefore, that the arrangement obtaining in the Elephants is
purely secondary. Professor Osborn has put forward the reasonable view[136]
that the vertical limbs of all these colossal creatures are due to "an
adaptation designed to transmit the increasing weight" of these animals.
The huge bulk of the body is better borne by vertical pillars than by an
angulated limb. Other points, however, such as the exposure of the
cerebellum, the two venae cavae, the five digits, and the absence of a
third trochanter, argue a low position for the Proboscidea in the Eutherian
group.

The group can be readily divided into two families, the Elephantidae and
the Dinotheriidae. We will commence with the former.

The Elephants proper, ELEPHANTIDAE, differ from the Dinotheriidae in, and
are characterised by, a number of anatomical features. They possess long
tusks (incisors) either in both jaws, or, if only in one jaw, in the upper.
The molar teeth are very large--so large that only a few of them are
simultaneously in use. There are but three definable genera of
Elephantidae, of which {218} _Elephas_ alone survives. This genus also
includes many extinct forms, both American and European, as well as Asiatic
and African. The entirely extinct genera are _Stegodon_ and _Mastodon_. The
group is clearly one dwindling towards extermination. From the Middle
Miocene downwards these great "pachyderms" have existed; and from the
Miocene up to Pleistocene times they were almost world-wide in range and
numerous in species.

The genus _Elephas_ comprises usually large, but occasionally (the pygmy
Elephant of Malta) quite small forms. The external features of the genus
differ slightly in different species, and will therefore be described in
relation to those species which we shall notice here. The vertebral formula
is C 7, D 19-20, L 3-5, Sa 4-5, Ca 24-30, or even more.

The bodies of the vertebrae are remarkable for their shortness and for the
very flattened articular surfaces.

[Illustration]

FIG. 116.--A section of the cranium of a full-grown African Elephant, taken
to the left of the middle line, and including the vomer (_Vo_) and the
mesethmoid (_ME_); _an_, anterior, and _pn_, posterior narial aperture. ×
1/12. (From Flower's _Osteology_.)

The skull is large and massive. Its large and heavy character is, as has
been stated in the definition of the sub-order, due to the immense
development of air cavities in the diploe; the diameter of the wall of the
skull is actually greater than that of the cranial cavity. These cavities
are not obvious in the young animal. They are most conspicuous in the
roofing bones of the skull, but are seen elsewhere, and thicken the basis
cranii, {219} the maxillae, and so forth. This state of affairs, together
with the presence of the huge tusks, has, as it were, pushed back the nasal
orifices to near the top of the skull in a very Whale-like fashion. As in
the Cetacea, the nasal bones are limited in size, and the premaxillae send
up processes to join the frontals and the nasals. There is a straight and
somewhat slender zygomatic arch, but the orbit is not separated from the
temporal fossa. The malar bone is small, and, as in Rodents, forms the
middle part of the zygoma. This is not the case with most Ungulata. The
symphysis of the mandibles forms a spout-like rim. The scapula has a narrow
prescapular, but a very wide postscapular region. The spine has a strong
process projecting backwards from near its middle; this is a point of
likeness to certain Rodents. No Elephant has a clavicle. The most
remarkable feature about the fore-limb is the separation and crossing of
the radius and ulna. The arms of these animals are permanently fixed in the
position of pronation. The foot is short, and the bones of the carpus are
serially arranged. There are, however, traces of a commencing interlocking
of these bones in many forms. The hind-feet are somewhat smaller than the
fore-feet, and the tibia and fibula are both developed.

As to the teeth, this genus is to be distinguished from allied forms by the
presence of tusks in the upper jaw only. These tusks have no bands of
enamel such as characterise those of _Mastodon_. They are incisors. There
is, however, a trace of the former enamelling in the shape of a patch at
the tip, which soon wears away. The molar teeth of _Elephas_ are so large
that the jaws cannot accommodate more than at the most two and a part of a
third at a time. These are gradually replaced by others to the number of
three, the replacement of teeth suggesting that of the Manatee. Each molar
is deeply ridged, the interstices between the ridges being filled up with
cement. As the tooth wears away, therefore, the surface continues to be
flat. Each ridge consists of a core of dentine surrounded by a coat of
enamel. The number of these ridges varies greatly from species to species.
The Indian Elephant is one of those which have the greatest number of
plates in a single tooth, as many as twenty-seven.[137] Of the six molars
which {220} eventually appear, the first three are considered to correspond
to premolars. But successional teeth are rare in the genus; that is to say
as far as concerns the molars, for the tusks have their milk forerunners.
As to the molars it is apparently only _E. planifrons_ which certainly
shows a milk dentition. In _Mastodon_ and older types a milk dentition is
commoner.

The viscera of the Elephant have been examined by many zoologists. The
latest paper, dealing chiefly with the African species, but containing
facts about its Indian congener also, is quoted below.[138] The Elephant is
remarkable in possessing, in addition to the three usual pairs of salivary
glands present in mammals, a fourth, situated in the molar region, and
opening on to the cheek by many pores. This gland is especially well
developed in Rodents. There is a gland which may be mentioned in this
connexion, though it opens externally between the eye and ear, known as the
temporal gland; its use does not seem clear. The thoracic cavity of the
Elephant, as may be inferred from the large number of ribs, is very large
as compared with the abdominal.

The stomach is simple in form, and the epithelium of the oesophagus does
not extend into it as is the case with the Horse and Rhinoceros. A gland or
a collection of smaller glands occurs in the stomach, and recalls the
"cardiac gland" of the Wombat and the Beaver, also that of the Giraffe. The
large intestine is long, rather more than half the length of the small
intestine. The caecum is well developed in these animals. The liver has a
very simple form, being but slightly lobulated. It is actually only
bilobed, but it is important to notice that this division does not
correspond to the two halves of the liver. As shown by the attachment of
the suspensory ligament, one half consists of the left lateral lobe alone,
the other half embracing the remaining primary lobes. The simplicity of the
liver looks like an archaic character. No Elephant has a gall-bladder. The
lungs again are simple in form through their slight lobulation. Each half
in fact is without subdivisions, and is of a triangular form. In this the
Elephants resemble the Whales, as in the simple liver. In both cases
probably the likeness is due to the permanence of primitive features of
organisation. The brain[139] of the Elephant {221} has hemispheres which
are extremely well convoluted; but they leave the cerebellum entirely
uncovered. This suggests a brain which is a great specialisation of a low
type. The brain has been particularly compared with that of the Carnivora,
with which group the Elephants agree in the characters of the placenta. It
is, however, always a matter of the very greatest difficulty to compare the
brains of mammals belonging to different orders.

There are but two living species of Elephant, of both of which we shall now
proceed to give some account. Only a few of the rather numerous fossil
forms can be touched upon here.

The African Elephant, _E. africanus_, has been sometimes referred to a
distinct genus or sub-genus, _Loxodon_, by reason of the lozenge-shaped
areas on the worn grinding-teeth. It lives, as its name denotes, in Africa.
This species has a number of external features which enable it to be
distinguished from the Oriental Elephant. The head slopes back more, and
has not the two rounded bosses which give so wise a countenance to the
Indian species. The ears are very much larger. The tip of the trunk has a
slight triangular projection on both the lower and the upper part of the
circumference of the aperture. There are four nails on the fore-feet and
three on the hind. As in the Indian form, the toes are all bound together,
and do not appear for any part as free digits. A thick pad of fat, etc.,
makes the animal when alive look as if plantigrade, whereas it is, as a
matter of fact, digitigrade. In internal features the most prominent
difference from _E. indicus_ is in the molar teeth, which are ridged by
much fewer ridges. The outside number for a single tooth in the present
species is 10 or 11. In _Elephas indicus_ on the other hand there are as
many as 27.

The African Elephant, thinks Sir Samuel Baker, reaches a height of about 12
feet, and it will be remembered that the notorious "Jumbo" was found to be
11 feet high at the shoulder. The tusks are found in both sexes, as in the
Indian beast, but are relatively larger in the female in the species now
under consideration. It is also a rather more active creature, and is more
savage;[140] however it can be tamed, as is shown by several {222}
specimens which have been and are in the possession of the Zoological
Society, and other proprietors. It was apparently used in the past. Certain
Carthaginian coins are stamped with a figure of the African Elephant; but
in Africa no attempts are now made to utilise this creature except for food
and ivory.

[Illustration]

FIG. 117.--African Elephant. _Elephas africanus._ × 1/56. (After Sir Samuel
Baker.)

The meaning of an Elephant as an emblem. upon a coin appears to be
eternity, and there is no question but that the {223} Elephant is a
long-lived animal. It is said that it hardly reaches proper maturity before
forty, and that 150 years is not beyond probability in the way of
longevity. Even longer periods have been assigned to it.

The tusks of the Elephant are by no means necessarily sexual adornments,
used for fighting purposes only. The African Elephant is a most
"industrious digger," and grubs up innumerable roots as food. It appears to
be a fact that during these operations the right tusk is mainly used, and
in consequence that tusk is shorter as well as thinner than the other. Two
average tusks would weigh respectively 75 and 65 lbs., the latter of course
being the weight of the more worn right tusk. These weights, it should be
observed, by no means indicate the limits to which finely-developed tusks
can attain. The very heaviest tusk known to Sir Samuel Baker[141] weighed
188 lbs. This was sold at an ivory sale in London in the year 1874. The
pace of the African Elephant, says the same authority, is at most at the
rate of fifteen miles an hour at first, and of course in a furious rush.
This pace cannot be kept up for more than two or three hundred yards, after
which ten miles an hour is a better approximation to the rate which can be
kept up for long distances.

The Indian Elephant, _Elephas indicus_ (or _Euelephas indicus_, if the
genus _Loxodon_ is to be accepted), is better known and has been longer
known than the African. It occurs in India and Ceylon, and in some of the
Malayan islands, the Elephants of which latter parts of the world have been
regarded as a distinct form, an apparently unnecessary procedure.

[Illustration]

FIG. 118.--Indian Elephant. _Elephas indicus._ × 1/54. (After Sir Samuel
Baker.)

This species does not stand so high at the shoulder as the African; its
back is more rounded in the middle. The trunk has but one pointed tip;
there are five nails on the fore- and four on the hind-feet. As this
species comes from India and the East, it has been longer as well as better
known than the African form. Thus many of the stories and legends that have
congregated round Elephants apply really to this form. As is well known,
the Indian Elephant is much used as a beast of burden, and for other
purposes where its huge strength renders it invaluable. But its great
drawback as a servant of man is its great independability. On the one hand
we have furious, vicious, and generally unreliable {224} Elephants, and on
the other perfectly docile creatures, who obey the slightest hint from
their driver. Huge though the Elephant is, it is frequently a timid beast.
Sir Samuel Baker relates how one which he was riding fairly bolted at the
sight of a Hare. To {225} be bolted with by an Elephant is far from
pleasing, though a rather exciting event. It makes for the nearest jungle
at once, being, much more than the African species, an inhabitant of
forest. And in rushing through the dense undergrowth, the occupiers of the
Elephant's back are apt to be swept off or cut to pieces by innumerable
thorns.

Elephants, no doubt of the Indian species, were used by the Persians in
battle, and from fifteen which were captured at the battle of Arbela some
notes were drawn up by Aristotle. In stating that the animal reaches an age
of 200 years, the naturalist and philosopher was probably not very far out.
The mode of Elephant-catching as related by Aristotle is that pursued at
the present day. Then, as now, tame Elephants were made use of as decoys.
Pliny,[142] who was apt to confound fact and fiction in a somewhat
inseparable tangle, had something to say about Elephants, both Indian and
African. Serpents, he thought, were their chief enemies, which slew them by
coiling round them and thrusting their heads into the trunk, and so
stopping respiration. In Europe Elephants were first seen in the year B.C.
280. Pyrrhus used them in his invasion, and copying his example the Romans
themselves learnt to use Elephants. The first Elephant seen in England
arrived in the year 1257, presented by the King of France to Henry III. It
was kept in the Tower (for long afterwards a menagerie), and died at twelve
years of age. Much use of the Elephant has been made in symbols. We have
spoken of the African Elephant on Carthaginian coins as an emblem of
eternity. The Oriental Elephant resting on the back of a tortoise and
supporting the world is the same idea; and it is instructive to note that
remains have been found in the Siwalik Hills of a tortoise which would have
been actually big enough to support the creature, even "Jumbo," who weighed
6½ tons. Another symbol is that of an Elephant upon whose back is a child
with arrows; this occurs on a medal of the Emperor Philip. It can perhaps
hardly signify the eternity of a strong human feeling!

The intelligence of the Elephant has been both exaggerated and minimised.
Perhaps the most elaborate attempt to endow the beast with unusual mental
perceptions is that of Aelian, who related that an Elephant carefully
watching his keeper, wrote after him with his trunk letters upon a board.
That the animal does {226} possess a good deal of brains, seems to be shown
by the way in which a well-trained animal will obey the slightest sign of
the mahout in India. According to Sir Samuel Baker, localities which
produce in abundance particular kinds of fruit are remembered, as well as
the time at which the fruit will be at its best. Stories of revenge, which
are numerous enough, attest, so far as their data are to be accepted as
accurate, the power of memory possessed by the Elephant.

In spite of their longevity, however, Elephants, unlike Rome, have not been
built for eternity. We can only find two living species; but in past times
Elephants were very numerous. They commenced, so far as we know, in the
Miocene.

The existing forms are known in a fossil, or at least sub-fossil state,
from diluvial deposits; and it is interesting to note that the African
Elephant had formerly a wider range than now. Its bones (described as _E.
priscus_) have been met with in Spain and Sicily.

One of the best known of completely-extinct Elephants is the Mammoth, _E.
primigenius_. This great Elephant in most respects more nearly approached
the existing Indian Elephant. The teeth have quite as numerous plates. The
tusks were enormous, reaching a maximum length of 15 feet; they were much
curved upwards as well as outwards. A large tusk weighs as much as 250 lbs.
The Mammoth was of exceedingly wide range. Not only was it found in various
parts of Europe, but it was especially abundant in Siberia, as is
exemplified by the fact that for the last two hundred years as many or more
than 100 pairs of tusks annually have been sold from that region. It also
occurred in America together with forms at least not far removed from it,
such as _E. columbianus_. Mammoths have been more than once found as entire
carcases in the frozen soil of Siberia. The first was discovered in the
year 1799, and rescued some years later for the St. Petersburg Museum. This
example showed that the Mammoth, unlike existing Elephants, was covered
with thick wool mingled with long and more bristly hairs of some 10 inches
in length. The softer wool formed a kind of mane beneath the neck, which
hung down as far as the knees. Another carcase was discovered later by
Lieut. Benkendorf, who did not save it, but was nearly swept along with it
into the sea by a flood. These creatures died in the position in which they
were found by being bogged when in search of vegetation or water. {227}

How primeval man, with his inferior weapons, slew the Mammoth is not easy
to understand; but that they were contemporaneous is clearly shown by
associated remains, and by the notorious sketch of the Mammoth on a piece
of its own ivory, in which curved tusks and a forehead like that of an
Indian Elephant are plainly to be seen. Although it was only so recently as
the year 1799 that an example of this great creature was actually studied
on the spot, and removed to St. Petersburg, the existence of Mammoths and
of ivory is a matter of much more ancient knowledge. M. Trouessart
relates[143] that fossil ivory was known to the Greeks. Theophrastus spoke
of ivory imbedded in the soil, and the tusks were recovered by the Chinese.
It is a curious fact that the Chinese described and figured the Mammoth as
a kind of gigantic Rat. The likeness between the elephantine molar and that
of Rodents has been commented upon; but the existence of its tusks below
the level of the ground led the Chinese Natural Historians to consider that
the ways of life of the Mammoth were those of the Mole. As to the carcases
themselves, the Chinese said that the flesh was cold, but very healthy to
eat. This expression can hardly be explained, except upon the view that
fresh carcases were known to that people long before they were known to us
of the Western world. The value of the Mammoth ivory was known to
antiquity; the famous Haroun-al-Raschid gave to King Charlemagne not only a
pair of living Elephants, but a "horn of Licorne," which seems undoubtedly
to have been a name for the tusks of the Mammoth. For in an account of the
sacred treasures of Saint Denis, published in the year 1646, the author
states this to be the fact.

The causes of the disappearance of the Mammoth are not easy to understand.
Some held that it was a naked animal like the existing Elephants, and that
the lowering of the temperature in Siberia proved fatal; it is, of course,
now certain that it was clothed with dense woolly hair. Along with the
bogged corpses of the great pachyderm, numerous trunks of pine-trees have
been found, together with associated remains of other animals now extinct
in that neighbourhood. Thus it is plain that Siberia was once covered by
mighty forests, through which the Mammoth roamed. The decay of these
forests, upon whose branches the Elephant fed, as is attested by the
remains of pine leaves found {228} in the interstices of its teeth, was the
signal for the disappearance of their most colossal inhabitant.

The large number of remains of this and of other extinct species of
_Elephas_ in this country gave rise to the supposition that they were
Elephants brought over by Caesar to aid in the subjugation of these
islands. The Rev. J. Coleridge (father of the poet) pointed out that though
Caesar in his _Commentaries_ made no mention of any such importation of
Elephants, a passage in the _Stratagems_ of Polyaenus expressly mentions
that Cassivelaunus was confronted by the Romans with an Elephant clad in a
coat of mail, by whose aid the crossing of the Thames was effected. At the
time that attention was called to this (1757) it was not popular to hint at
the possibility of fossils. So that fact, conveniently historical, served
to explain away a difficulty. It is remarkable that the Elephant, common
enough of course in Asiatic monuments, actually occurs in English
architecture. Mr. Watkins, from whose interesting work (_Natural History of
the Ancients_) a good many of the facts detailed here are drawn, tells us
that the church of Ottery St. Mary has an Elephant's head sculptured on one
of its pillars. The same ornament appears in Gosberton Church,
Lincolnshire. Whether this has anything to do with a reminiscence of
formerly existing Elephants is a hard question to answer. In this figure of
an Elephant the trunk has a spiral representation, and the trunk of an
Elephant is believed by some to be intended by the common "so-called
Pictish ornamentation" in Scotland; this spiral alone is to be seen
constantly. If it is a reduction of an Elephant to its simplest terms, it
is highly interesting as an almost undoubted survival of remembrance of
Elephants. For at such a period we cannot use the memories of Crusaders or
others who may have visited the East to explain the facts. The sculptured
Elephants' heads might conceivably be so explained.

The name Mammoth, thinks Mr. Watkins, may be derivable from the Arabic word
Behemoth. He quotes a writer, who first described the beast in 1694, as
using the two words indifferently. The Arabs, moreover, were then as they
are now great ivory traders; and in the ninth and the two succeeding
centuries explored the confines of Siberia, as they now do the forests of
Africa, for ivory. The "Behemoth" of Job "eateth grass as an ox.... He
moveth his tail like a cedar" (the Hippopotamus has a much more {229}
stumpy appendage). "Behold, he drinketh up a river, and hasteth not" is
surely much more suggestive of the copious draughts of an Elephant than the
possibly equally copious but not so visible libations of a Hippopotamus.

The most ancient of the true Elephants (genus _Elephas_) is _E.
meridionalis_. It is of the African type, _i.e._ the plates of the molar
teeth are not abundant, and are not so many as in the existing _E.
africanus_. It seems to have been one of the largest of Elephants, standing
4 metres high. Its remains are abundant in Europe, and are known also from
England. Like this species _E. antiquus_ is also of the African type. It
was contemporary with man. Certain dwarf or "pony" races found in caves in
Malta, and called _Elephas melitensis_ or _E. falconeri_, are believed to
belong to this species. Mr. Leith Adams, who described these[144] remains,
placed them in two dwarf species called by the names used above, and found
associated with them a larger form, which he referred to _E. antiquus_. The
existence of these animals in Malta seems to argue at least its former
larger dimensions, and the presence of more abundant fresh water. The
remarkable swimming capabilities of the Elephant do not necessarily imply
either a former absence of land connexion or, on the other hand, its
existence. Nor as a third possibility can it be suggested that the dwarf
size argues an island of limited dimensions, when we bear in mind the huge
tortoises of the Galapagos and some other islands. It is important to
notice that Elephants of the African type (_Loxodon_) were not formerly
absent from India. _E. planifrons_ was one of these.

The genus _Stegodon_ is so called from the fact that the molar teeth, seen
in longitudinal section, present a series of roof-shaped folds, the
interstices between which are not, or are, imperfectly filled up with the
cement which in _Elephas_ reduces the surface of the teeth to a level
plane. This genus is exclusively Asiatic, and is Miocene to Pleistocene in
time range. The number of ridges on the molars is small, not more than two.
The incisors (tusks) have no enamel; the skeleton generally is like that of
_Elephas_, between which and _Mastodon_ the present genus is intermediate.
Among the four or five species is _S. ganesa_ (called after the Indian
Elephant-headed divinity), with tusks 10 feet long, to be seen at the
British Museum of Natural History. {230}

The last genus of the family Elephantidae is _Mastodon_, so called from the
structure of the molar teeth. These are provided with but few transverse
ridges, not more than five, so that their structure is intermediate between
those of _Dinotherium_ and those of _Stegodon_. Between the ridges are
sometimes isolated, boss-like protuberances (whence the name of
_Mastodon_), produced by a subdivision of the ridges. There is either but
little or no cement between the ridges. This genus differs from nearly all
other Elephantidae by the possession of milk molars, which occasionally
persist throughout life, the permanent dentition in those cases being a
mixture of milk and permanent teeth, as has been (erroneously) stated of
the Hedgehog.[145]

The tusks (incisors) are sometimes present in both jaws, and as they have,
during youth at any rate, a coating of enamel, the likeness to the
chisel-shaped incisors of Rodents is patent. In connexion with the
implantation of incisors in the lower jaw, many species have a prolongation
of the bones of that part of the skeleton. In the bones, generally, there
is not very much difference from _Elephas_, but the forehead is a little
less pronounced. The genus existed from the Miocene and became extinct in
the Pleistocene. It was nearly world-wide in range, being known from all
four continents. Naturally with this very wide range was associated a large
number of species. Zittel enumerates no less than thirty-two.

This genus is the only one of the Elephantidae which extended its range
into South America, where the remains of two species occur. The bones of
these great Elephants have attracted attention for some centuries. They
were often held to be the bones of giants (as they actually were!), and in
one case were ascribed to a deceased monarch, Teutobochus. The American
Indians considered that equally gigantic men lived who were able to combat
these great Proboscideans. There are legends of the Mastodons as living
animals, which is quite probable, considering their geological age. There
is a curious parallelism between the legends of two such widely-separated
localities as North America and Greece. Buffon relates how among the
Indians of Canada there was a belief that the Great Being destroyed both
Mastodons and men of equal proportions, with thunderbolts. With this we may
perhaps compare the story of the destruction of Typhoeus by Zeus, who {231}
also used thunderbolts. One of the giants was not slain, but was compelled
to stand and bear up the heavens. Atlas holds thus the position of the
Elephant supporting the globe of Indian mythology.

[Illustration]

FIG. 119.--_Dinotherium giganteum._ Side view of skull, 1/15th natural
size. Miocene, Germany. (After Kaup.)

The genus _Dinotherium_, sole representative of the family DINOTHERIIDAE,
differs in a number of important particulars from the true Elephants. In
the Elephants, if there is but a single pair of incisors, these are found
in the upper jaw; in _Dinotherium_ there is apparently but a single pair,
but these are implanted in the lower jaw, the symphysis of which is much
prolonged and greatly bent downwards, so that the tusks emerge at right
angles to the long axis of the head, and are even bent backwards. The molar
teeth are five in number on each side of each jaw and are bi- or
tri-lophodont, not unlike those of the Tapir. There is no cement in the
valleys between the ridges of these teeth, and there is a regular
succession, the premolars being two and the molars three.[146] All the
teeth are in use at the same time, {232} their small size enabling them to
be accommodated in the jaw together. The skull of _Dinotherium_ is lower
than that of _Elephas_ or _Mastodon_. The bones of the skeleton generally
are like those of _Elephas_.

Though a suggestion of marsupial bones attached to the pelvis has been
discredited, there is no doubt that _Dinotherium_ occupies the most
primitive position among the Proboscidea; but at the same time it cannot be
regarded as the ancestor of Elephants, as it is so much specialised in
various ways. The incisors for one thing forbid this way of looking at the
creature. It is an ancient genus found in beds of Miocene age in Europe and
Asia. It is not known from America. The creature was larger than any
Elephant. Eighteen feet in length has been assigned to it. The enormous
weight of the lower jaw and tusks seems to argue that it was at least
partially aquatic in habit, and that it may have used these tusks for
grubbing up aquatic roots or for mooring itself to the bank. At first there
were naturalists who considered it as an ally of the Manatee, and the skull
is not unsuggestive of that of the Sirenia.

_Pyrotherium_ has been referred to the Proboscidea; but our knowledge of
that form is limited to a few teeth from Patagonian rocks of an uncertain
age.[147] They are simple bilophodont molars, very like those of
_Dinotherium_. A tusk has been found in the neighbourhood of these teeth
which may possibly belong to the same animal; but it is uncertain.

SUB-ORDER 7. HYRACOIDEA.

This group of small mammals contains only one well-marked genus which is
usually named _Hyrax_, although _Procavia_ seems to be the accurate term.
Popularly these creatures are known as Coneys. They have a singular
resemblance to Rodents, the short ears and much reduced tail, besides the
squatting attitude adopted, contributing to this merely skin-deep likeness.
They agree with other Ungulates in the structure of the molar teeth, which
are much like those of _Rhinoceros_; in the absence of a clavicle; in the
absence of an acromion; in the reduction of the digits of the limbs to four
digits in the manus and three in the pes. On the {233} other hand they
differ from most Ungulates in the incisors growing from persistent pulps, a
point in which they resemble the Rodentia. The muffle also is split as in
those animals. The Hyracoidea are peculiar in the fact that in addition to
the caecum at the junction of the small and large intestines, there are a
pair of caeca (bird-like in being paired) some way down the large
intestine. The dorsal vertebrae are unusually numerous, 22. The adult
dentition according to Woodward,[148] who has recently examined the matter,
is I 1/2 C (1/0) Pm 4/4 M 3/3, while the milk dentition is I 3/2 C 1/1
Pm 4/4.

[Illustration]

FIG. 120.--Cape Hyrax. _Hyrax capensis._ × 1/8.

The inclusion of the canine of the permanent set of teeth in brackets
signifies that it is the milk canine which occasionally persists. It should
further be remarked about the teeth that they are both hypselodont and
brachyodont, the extremes being connected by intermediate forms. Another
peculiarity of the genus is the dorsal gland, which is covered with hair of
a different colour to that covering the body generally. This is present in
all species.

The genus _Hyrax_ (the most recent authority on the subject, Mr. Oldfield
Thomas,[149] only allows one genus) is limited in its range to Ethiopian
Africa and to Arabia, including Palestine, It does not reach Madagascar.
Mr. Thomas allows fourteen species with two or three sub-species. {234}

Some of the Coneys live in rocky ground, while others, formerly placed in
the genus _Dendrohyrax_, frequent trees, in holes in which they sleep. The
Coney of the Scriptures is familiar, who is "exceeding wise," though a
"feeble folk." But the further observation that he "cheweth the cud but
divided not the hoof," is obviously entirely wrong. As to the wisdom, it is
said that this beast is too wary to be taken in traps; while the suggestion
of chewing the cud is, according to Canon Tristram, to be interpreted in
the light of a habit of working and moving its jaws which the animal has.
The traveller Bruce kept one in captivity to see if it did really chew the
cud, and found that it did!

       *       *       *       *       *


{235}

CHAPTER X

UNGULATA (_continued_)--PERISSODACTYLA (ODD-TOED UNGULATES)--LITOPTERNA

SUB-ORDER 8. PERISSODACTYLA

[Illustration]

FIG. 121.--Bones of the manus A, of Tapir (_Tapirus indicus_). × 1/5. B, of
Rhinoceros (_Rhinoceros sumatrensis_). × 1/5. C, of Horse (_Equus
caballus_). × 1/8. _c_, Cuneiform; _l_, lunar; _m_, magnum; _p_, pisiform;
_R_, radius; _s_, scaphoid; _td_, trapezoid; _tm_, trapezium; _u_,
unciform; _U_, ulna; _II-V_, second to fifth digits; _V_ in B, and _II_ and
_IV_ in C, represented by rudimentary metacarpals. (From Flower's
_Osteology_.)

These Ungulates derive their name, which is that given by the late Sir
Richard Owen, from the fact that the middle digit of the hand and foot is
pre-eminent. As will be seen from Fig. 121, the axis of {236} the limb
passes through the third finger, which is larger than any of the others,
and is symmetrical in itself. In this the present group contrasts with the
Artiodactyla, where the axis is not "mesaxonic," but where there are two
digits, on either side of the axis, which are symmetrical with each other.
This arrangement of the limbs is highly characteristic, but appears to be
not quite universal. In the Titanotheres, which form a group of the
Perissodactyles, the fore-limbs are not quite accurately mesaxonic. Nor on
the other hand can all Ungulates which show the Perissodactyle condition be
safely included in the present group. The ancient Condylarthra and the
Litopterna show precisely the same state of affairs. But other features in
their organisation lead to their separation from the Perissodactyles, of
which, however, the Condylarthra are probably ancestors. The Litopterna on
the other hand, which possess even one-toed members like _Equus_, are
believed to represent a case of parallelism in development. The number of
functional toes varies from four to one. In the ankle joint the astragalus
either does not, or does only to a comparatively slight extent, articulate
with the cuboid as well as with the navicular bone. Moreover the fibula
when present does not as a rule articulate with the calcaneum. In the
opposed group of Artiodactyles the precise reverse of these conditions
obtains. It is usually stated as part of the definition of this group that
they do not possess horns of the type of those met with in the Cervicornia
and Cavicornia. But the strong bony bosses on the skull of many
Titanotheres, so curiously reminiscent of those of the not nearly related
_Dinoceras_ and _Protoceras_, may well have supported horns of the Ox and
Antelope pattern.

[Illustration]

FIG. 122.--Bones of the manus of Camel (_Camelus bactrianus_). × 1/8. _c_,
Cuneiform; _l_, lunar; _m_, magnum; _R_, radius; _s_, scaphoid; _td_,
trapezoid; _u_, unciform. (From Flower's _Osteology_.)

The teeth of the Perissodactyles are lophodont, more rarely bunodont. The
selenodont Artiodactyle form of molar is not met with. The dental formula,
moreover, is at least near the {237} complete one, the more modern forms as
usual being the more deficient in numbers of teeth.

The dorso-lumbar vertebrae are as a rule twenty-three; but the extinct
Titanotheres are again an exception; for, at least in _Titanotherium_,
there are but twenty of these vertebrae--an Artiodactyle character. The
femur has a third trochanter. There are so few recent Perissodactyles that
an enumeration of the distinguishing characters of the viscera may very
probably be useless for purposes of classification. But the living genera
at any rate are to be separated from the living Artiodactyles by the
invariable simplicity of the stomach coupled with a very large and
sacculated caecum. The liver is simple and not much broken up into lobes,
and the gall-bladder is always absent. The brain is well convoluted. The
teats are in the inguinal region. The placenta in this group is of the
diffused kind.

[Illustration]

FIG. 123.--Anterior aspect of right femur of Rhinoceros (_Rhinoceros
indicus_). × ½. _h_, Head; _t_, great trochanter; _t_', third trochanter.
(From Flower's _Osteology_.)

The living Perissodactyles belong to three types only, indeed to three
genera only (in the estimation of most), which are the Horses, Tapirs, and
Rhinoceroses. But taking into account the extinct forms, they may be
divided primarily (according to Professor Osborn) into the four following
groups:--(1) Titanotherioidea, including but one family, Titanotheriidae;
(2) Hippoidea, including the families Equidae and Palaeotheriidae; (3)
Tapiroidea, with two families, Tapiridae and Lophiodontidae; and (4)
Rhinocerotoidea with families Hyracodontidae, Amynodontidae, and
Rhinocerotidae. It is conceivable, according to the same writer, that the
Chalicotheres (here treated of as a separate sub-order, Ancylopoda) should
be added to the Perissodactyle series.

[Illustration]

FIG. 124.--Side view of skull of Horse with the bone removed so as to
expose the whole of the teeth. _c_, Canine; _Fr_, frontal; _i_^1, _i_^2,
_i_^3, incisors; _L_, lachrymal; _m_^1, _m_^2, _m_^3, molars; _Ma_, malar
or jugal; _Mx_, maxilla; _Na_, nasal; _oc_, occipital condyle; _Pa_,
parietal; _pm_^1, situation of the vestigial first premolar, which has been
lost in the lower, but is present in the upper jaw; _pm_^2, _pm_^3, _pm_^4,
remaining premolars; _PMx_, premaxilla; _pp_, paroccipital process; _Sq_,
squamosal. (After Flower and Lydekker.)

FAM. 1. EQUIDAE.--This family, which includes the living Horse, Zebras, and
Asses, as well as a number of extinct genera agreeing with those types in
structure, may be defined by the possession of but one functional toe, the
two lateral ones being mere splints, or but little more. The molar teeth
are hypselodont, and {238} the premolars, with the exception of the first,
resemble the molars in their pattern. The orbit is completely surrounded by
bone. The incisors are chisel-shaped, with a pit on the free surface. The
canines are rudimentary if present. The radius and ulna are fused, as are
the tibia and fibula. Although for the sake of uniformity a family,
Equidae, is here separated from its allies, it is quite impossible owing to
the full state of our knowledge of this group to draw a really
hard-and-fast line between this family and the Palaeotheriidae. We shall
deal presently with the conjectured pedigree of the Horse, which naturally
involves that family, and which presents an unbroken series from four-toed
Perissodactyles to the present one-toed Horse, the various bones and teeth
becoming modified in the course of the descent "with the regularity of
clockwork." We are compelled to draw the line at functional second and
third toes; directly these are no longer used the animal is a Horse in the
strict sense! This is irrational and regrettable, but necessary for
practical purposes, if {239} we are to continue the plan of defining the
various families of Mammalia.

The genus _Equus_[150] contains not only the Horse, but the Asses and
Zebras. The genus is to be distinguished as regards external characters by
the following features:--The body is thickly clothed with hair; there is a
more or less bushy tail and mane; the colours are apt to be disposed in
stripes of black or blackish upon a yellowish brown ground; this is of
course best seen in the Zebras, but the wild Asses also have some traces of
it, if only in the single cross-bar of the African Wild Ass, and it is even
"reversionary" in the domestic Horse at times. There are no horns upon the
forehead or elsewhere; the fore-limbs or both pairs have a callous pad upon
the inside, which is possibly to be looked upon as an aborted gland,
possibly originally of use as secreting some odorous substance calculated
to enable strayed members of the herd to regain their companions. The
terminal phalanx of each of the (functionally) single digits is enclosed in
a large horny hoof.

The main internal features of structure which divide this genus of
Perissodactyles from the Rhinoceros or the Tapir, or from both, are: the
existence of strong incisors, three on each side of each jaw; there are
canines, but these are small and do not always persist in the full-grown
mare. They are popularly known as "tusks" or "tushes." The first of the
four premolars (the "wolf tooth") is small and quite rudimentary; it is
often absent. As there are three molars, the present genus has the
"typical" number of the Eutherian dentition, _i.e._ forty-four. In the
skull the orbit is--as it is not in Tapirs and Rhinoceroses--completely
encircled by bone. There is but one functional finger and toe on each hand
(Fig. 121 C) and foot; the second and third digits are represented by mere
splints, one of which may as an abnormality be enlarged, and reach nearly
as far as the well-developed digit. There are even occasionally traces of
digit number two.

The Horse, _E. caballus_, is to be distinguished from its congeners by the
small callosities on the hind-limbs which it possesses in addition to the
larger ones on the fore-limbs. The hairy covering of the tail is more
abundant, as is also the mane. The head too is proportionately smaller, and
the general contour {240} more graceful. Though Zebra markings are not
usual upon _E. caballus_, there are plenty of examples of--what we may
perhaps in this case term--a "reversion" to a striped state. The celebrated
"Lord Morton's mare,"[151] whose portrait hangs in the Royal College of
Surgeons, is an interesting case of this. It was as a matter of fact
thought to be an example of that rather doubtfully-occurring phenomenon,
"telegony." Its history is briefly this. The animal was the offspring of a
mare that had previously produced to a male Quagga a hybrid foal.
Afterwards a second foal was produced by the same mare to an Arab sire.
This foal, the one in question, was striped, and hence was thought to be an
example of male prepotency. But instances are known of unquestioned Horses
which show the same stripes, such as a Norway pony which had not even
_seen_ a Zebra!

A last remnant of the naked palm of the hand and sole of the foot is left
in the shape of a small bare area, smaller in the Horse than in the Asses,
known technically as the "ergot," the term being that of the French
veterinarians. As already mentioned, the Horse differs from the Asses and
Zebras in the fact that the hind-limbs have callosities on the inner side.
They are known as "chestnuts," and their nature has been much disputed. It
has been suggested that they are the last rudiment of a vanished toe; but
in all probability they are, as already suggested, traces of glandular
structures, which are common, upon the limbs in many animals (see above, p.
12).

It is a singular fact that there are apparently no wild Horses of this
species. The case is curiously analogous to that of the Camel, which also
is only known as feral or domesticated. Why the Horse should have become
extinct as a wild animal, considering that when it does run wild it can
thrive abundantly, is impossible to understand. Sir W. Flower thinks[152]
that "the nearest approach to truly wild horses existing at present are the
so-called Tarpans, which occur in the Steppe country north of the sea of
Azov between the river Dnieper and the Caspian. They are described as being
of small size, dun colour, with short mane and rounded obtuse nose." But he
adds that there is no evidence to prove whether they are really wild. In
favour, however, of their possibly being wild and indigenous European
Horses, may be {241} mentioned the fact that their general build and
appearance is highly suggestive of the wild Horses sketched by primitive
man upon ivory.

A really wild Horse, and possibly the ancestor of the European domestic
Horse, is _E. przewalskii_ of the sandy deserts of Central Asia. This
animal has been believed to be a mule between the Wild Ass and a feral
Horse; but if a distinct form, and probability seems to urge that view, it
is interesting as breaking down the distinctions between Horses and Asses.
The species possesses the four callosities of the Horse, but has a poorer
mane and an asinine tail.

There is no question that the Horse has been a domestic animal for very
many centuries. Hieroglyphics appear to show that the Egyptians had not
originally domesticated the Horse; it seems to have been first introduced
among them by the Hyksos or Shepherd Kings.[153] Whatever the date may be,
it is certain that considerably anterior to the Egyptians the Assyrians and
Phoenicians possessed Horses. In Western Europe the date of the
introduction of the Horse seems to have been during the bronze epoch. Lord
Avebury[154] has pointed out that out of eighteen cases of graves in which
the remains of Horse were found, twelve contained metal implements, _i.e._
66 per cent. This does not of course prove that the Horse was domesticated
at that period, but it throws doubt upon the earlier occurrence of the
Horse in abundance. The Horse, however, does occur on the Continent
associated with the remains of man during the Quaternary period.[155]

Messrs. Cuyer and Alix enumerate between fifty and sixty domesticated races
of Horse, not counting the supposed wild varieties which have been already
referred to. These may be further subdivided; for instance, under the race
"pony" we may distinguish the Irish, Scotch, and Shetland varieties, all of
which, however, according to Sanson, have originated in Ireland. They are
used, remark the authors above quoted, "par les jeunes filles des lords
pour leurs promenades." The Arab, the Barb, the Suffolk Punch, etc., are
among the numerous races of domestic Horses, into which to enter properly
would require another volume, and that of large size. {242}

The Asses and Zebras differ from the Horse in the characters mentioned
under the description of _Equus caballus_. In addition to these may be
pointed out a feature to which attention has been directed by Mr.
Tegetmeier.[156] According to him the period of gestation in the Horse is
only eleven months; in the others more than twelve.

[Illustration]

FIG. 125.--Asiatic Wild Ass. _Equus onager._ × 1/20.

Opinions as to the number of species of Asses differ. On the most liberal
estimate there are three Asiatic and two African species. The best known of
the Asiatic Wild Asses is the Onager, _E. onager_. It is of a uniform
yellowish, "desert" colour, with a dark stripe along the middle of the
back, and is found in Persia, the Punjab, and the country of Cutch. The
creature is of great swiftness; it has been stated to be untameable, but
Mr. Tegetmeier makes the absolutely opposite statement that the Ass
occasionally "becomes so tame as to be troublesome"! The Syrian Wild Ass,
_E. hemippus_, hardly, if at all, differs from this.

[Illustration]

FIG. 126.--Nubian Wild Ass. _Equus africanus._ × 1/20.

The Kiang, _E. hemionus_, seems to have more claims to distinctness. In the
first place it has a more limited and a {243} different distribution; it is
confined to the high tablelands of Thibet at an elevation of 15,000 feet
and upwards. In correlation with this habitat it has a thicker and more
"furry" coat, which is, moreover, of a darker shade than that of the
Onager. This coat is shed in the summer, and replaced by one which is not
so dark in hue. It is an interesting fact that the African Wild Asses
approach to the zebra type in having at least traces of stripings. There
are apparently two species. The best known, the Nubian Ass, _E. africanus_,
is probably the parent of the domestic donkey. It has a dorsal longitudinal
stripe, and another across the shoulder--in legend the marks of the
Saviour. The matter of the name of this Ass seems difficult to decide. It
has been called also _E. asinus_ and _E. taeniopus_. It has been observed
that this animal has a great aversion to water, and a delight in rolling in
the dust--both of which characteristics argue a desert existence. But on
the other hand the Kiang will plunge boldly into streams, yet it would seem
to be the descendant of a purely desert form. The Ass is a longer-lived
{244} animal than the Horse. Mr. Tegetmeier calls attention to a donkey
living in 1893 which had been ridden fifty-five years previously. The
Horse, on the other hand, lives not much more than twenty-five years.

A second species of African Wild Ass, _E. somalicus_,[157] is distinguished
by its greyer colour, by the absence of the shoulder stripe, by the very
faint development of the dorsal stripe, and by the presence of numerous
cross stripes upon the legs. It has, too, smaller ears, and a longer and
more flowing mane. Mr. Lort Phillips, an experienced naturalist and
traveller, saw a herd of these Wild Asses in Somaliland, which he regarded
as being of quite a new species. A living example in the Zoological
Society's Gardens led Mr. Sclater to an identical conclusion, which was
supported, as he pointed out, by the fact that this Ass has a different
range to the African or Nubian Wild Ass.

Of the Zebras three species are usually allowed; these are _E. zebra_, the
"Mountain" or "Common" Zebra, _E. burchelli_, _E. grevyi_, as well as _E.
quagga_. Professor Ewart thinks that the Common Zebra, Burchell's, and the
Quagga are not very distinctly marked off from each other. No one, however,
has any doubt of the distinctness of _E. grevyi_. This latter differs from
the rest in its larger size, in the large head and ears, and in the marked
hairiness of the ears. It would seem to be a primitive type of Zebra, if
the fact that the occasional reversion of hybrids to a parent form be
allowed; for Professor Ewart found a cross-bred Zebra to present several
characteristics in the face-marking of this, the finest of the Zebra tribe.
Only four specimens of _E. grevyi_ have been exhibited alive in Europe--two
in Paris, and two in the Zoological Society's Gardens in London. The latter
were presented to Queen Victoria by King Menelek of Abyssinia. The species
was named by Professor A. Milne-Edwards in honour of a late President of
the French Republic, from an example also sent by King Menelek.

The Common Zebra has closer and darker stripes than Burchell's, but not
quite so close as in _E. grevyi_. It has also a very characteristic
arrangement of stripes on the withers in the form of a gridiron. This
latter is wanting in both the other species. In _E. grevyi_, in fact, this
part of the back is white. _E. zebra_ has also a dewlap in front. _E.
burchelli_ has fewer and broader {245} stripes, and between them lie in
many cases shadow-stripes of a faint brown.

[Illustration]

FIG. 127.--Burchell's Zebra. _Equus burchelli._ × 1/20.

All these animals, and the Quagga too, are absolutely confined to Africa.
Mr. R Crawshay,[158] in describing what he considered to be a new variety,
remarked upon the curiosity of _E. burchelli_. "They remain out in the sun
on the plains all day long, not retiring into covert at all. They are then
an intolerable nuisance to any one in pursuit of other game; indeed this
may be said of them at all times. If once they notice you, they draw in and
mob you in their curiosity--only, however, when one takes no interest in
them, for when they fancy they are the object of the intruder's attention,
no animals are more watchful and cunning in safeguarding themselves. If
only their curiosity were manifested in silence it would not so much
matter, but it vents itself in snorts and thundering stampedes, which puts
every beast within earshot on the _qui vive_."

Whether Burchell's Zebra[159] can be further subdivided into species or
sub-species appears to be doubtful. Dr. Matschie considers that _Equus
boehmi_ may be regarded as a valid form, and in addition to this two
sub-species, _E. burchelli granti_ and {246} _E. burchelli selousi_, have
been proposed for what are at most local races. But it is at present far
from certain whether their distribution favours this subdivision.

The Quagga was more striped than is sometimes represented in illustrations.
According to Dr. Noack, from whose paper[160] upon the animal I quote here,
the transverse stripes reached back as far as the buttocks; they were,
however, completely absent from the legs. The animal is, as every one
knows, probably completely extinct. In the year 1836 it was still abundant;
in 1864 the last specimen ever exhibited was received by the Zoological
Society. Mr. W. L. Sclater thinks that it may have survived in the Orange
River Colony as late as 1878, but admits that any certainty is difficult,
as it was frequently confounded by the Boers with Burchell's Zebra. Its
rarity is emphasised by the fact that it is not mentioned in the recent
work of that most skilful of hunters, Mr. F. Selous. Gaudry places the
Quagga nearest of all living Equidae to the _Hipparion gracile_ of Pikermi.

FOSSIL EQUIDAE.--The existing Equidae all belong to the genus _Equus_,
though there are some who would (quite unnecessarily) divide off the Zebras
as a genus _Hippotigris_. The genus _Equus_ itself goes back in time to the
Pliocene, during which epoch there lived in India _E. sivalensis_, the same
species according to some with the _E. stenonis_ of Europe. None of these
species, Old World or New, are easily to be separated from _E. caballus_.
But many names have been given to them. It is of course perfectly
conceivable that they may have differed among themselves as much as do the
existing Zebras and Asses, the separation of which would be hardly possible
did we know their bones only. There are, however, extinct genera,
undoubtedly related so closely to _Equus_ as to be placed in the same
family, though clearly separable as genera. _Hipparion_ is one of these
genera; its remains are known from Europe, Asia, and North Africa, from
beds of Miocene and Pliocene times. A large number of different species
have been described. It was a beast of about the size of a Zebra. The
principal characters are that each foot has three toes, of which, however,
the two side ones are smaller than the central toe. There is a marked round
fossa on the maxillary bone, a feature shared by the South American
_Onohippidium_.[161] The pattern of {247} the molar teeth is, too, a little
different from that of _Equus_. _Protohippus_ of the North American
Pliocene is also three-toed, but the two additionally-developed toes are
smaller than in _Hipparion_. Other forms are dealt with below in connexion
with the ancestry of Perissodactyles. It is a curious fact about
_Hipparion_, which is not now regarded as on the direct line of equine
descent, that the edges of the enamel plates of the molars may show a
complicated folding very like that presented by that clearly terminal form
of Perissodactyle life, the gigantic _Elasmotherium_. This is indicative of
high specialisation, which ended in extinction.

ANCESTRY OF THE HORSES.--The LOPHIODONTIDAE and the PALAEOTHERIIDAE are two
of the most interesting extinct families of Perissodactyles; for among them
we find what would appear to be the ancestral forms of both the existing
Tapirs and Horses. The Rhinoceroses also would seem to be derivable from
the Palaeotheriidae. The very vagueness of the characters of these
creatures, considered from a classificatory point of view, has led to much
diversity in their placing. This though gratifying to the evolutionist is
tiresome to the writer who wishes to give a methodical account of their
various characters. It will be best perhaps not to attempt an accurate
placing or to reconcile conflicting opinion, but to give some salient
features of osteology which lead to the belief in their relationship to
existing groups of Perissodactyles. A book upon the history of mammals
would be incomplete without some account of that well-ascertained series of
forms which seem to connect these primitive Perissodactyles with the modern
Horse. _Equus_, in fact, is not only the "show horse" of the doctrine of
evolution, but also the "stalking horse."

In the Eocene of both Europe and America are met with a number of forms
from which we may start. _Hyracotherium_, regarded on the one hand as the
type of a sub-family of the Equidae themselves, and on the other as a
member of the family Lophiodontidae, was a small-sized animal, three feet
or so in length; it possesses the complete Eutherian dentition with a
slight diastema. The orbits are not separated from the temporal fossa; the
fore-limbs were four-toed, the hind three-toed, with moderately long
metapodia, especially on the hind-feet. The shoulder blade {248} has a
well-marked coracoid process. The radius and ulna are separate; so too are
the tibia and fibula. _Eohippus_, belonging to the same sub-family, is
slightly more primitive; for the hind-feet have a rudiment of digit I.
_Orohippus_ is a little nearer to the Horses in that the molar teeth have
acquired a little further advance towards the equine type. Instead of the
tubercles of the teeth remaining for the most part separate, they have
fused into a set of ridges, of which, however, the pattern is less complex
than in the modern Horses. In other respects _Orohippus_ is much like
_Hyracotherium_. _Pachynolophus_ seems to be but a synonym.

The next stage is shown by _Mesohippus_, a Lower Miocene form, usually
referred to the neighbourhood of _Palaeotherium_. It has nearly lost one of
the toes of the fore-foot, a rudiment only remaining; the metapodials, at
any rate of the fore-feet, seem to be slightly increased in length. The
orbit is not encircled by bone, but there is a strong process from the
frontal, which nearly meets the zygomatic arch.

_Anchitherium_, from the Upper Miocene, is not far removed in structure
from the last-mentioned form; it is a trifle nearer the existing Horse in
several points. The ulna is further reduced and fused with the radius
below: the rudiment of digit V is still more rudimentary; the two lateral
digits are smaller in proportion to the central one than they are in
_Mesohippus_; the fibula is fused below with the tibia. From this form to
_Equus_ is a small series of steps, characterised by the still further
reduction of all the digits except III, by the still further reduction of
the already rudimentary ulna and fibula, and by the increasing depth of the
molar teeth, which are of course, in _Equus_, hypselodont.

Another interesting conclusion may seem to follow when we consider the
geographical range of the ancestral Horses. _Hyracotherium_ and
_Pachynolophus_ occurred both in the Old and New World. From them may have
arisen the Horses of both hemispheres. After that point there is a
division. _Mesohippus_ is American, and we get at _Equus_ in that continent
through _Desmatippus_ and _Protohippus_. On the other hand there are no
remains known of _Mesohippus_ in Europe; and unless subsequent researches
prove the existence of _Mesohippus_, we have to rely upon forms which are
placed with _Anchitherium_ and _Hipparion_.

It seems that in America the next genus in the direct line of equine
descent to _Mesohippus_ is _Miohippus_. It is smaller in {249} size than
_Anchitherium_, to be considered immediately. The odontoid process of the
axis is just beginning to assume the characteristic spout-like shape of
that of the existing Horse and many modern Ungulates. The median digit of
both fore- and hind-limbs has become greatly enlarged as compared with the
corresponding digit of earlier forms.

It is held, however, that _Anchitherium_ is not on the direct line of
descent either in America or in Europe, in both of which it occurs. Its
teeth are in some respects less Horse-like than in some of the more ancient
genera, to which the converse would be expected on the descent theory. Its
hoofs are much elongated and flattened, a mark of specialisation and not
appropriate to a creature holding an intermediate position in the equine
series. Both the American (_A. equinum_) and the European species (_A.
aureliense_) are of very large size, larger than its successors, and such
"alternations in bulk are unlikely."

The genus _Desmatippus_ of Professor Scott[162] fills in the gap between
_Miohippus_ and _Protohippus_. The molars and premolars are brachyodont,
but there is a thin deposit of cement in the tooth valleys, leading towards
the more complete filling of these valleys with cement, which is found in
_Protohippus_. This genus of Horses, of which there is at present but one
species, _D. crenidens_, was three-toed, and "the lateral digits, so far as
can be judged by fragmentary remains, were still fairly developed, and
though much more reduced than in _Miohippus_, appear to be somewhat less so
than in _Protohippus_."

To recapitulate, the following is the probable series of equines in
America--_Mesohippus_, _Miohippus_, _Desmatippus_, _Protohippus_.

The development of the limbs of the Horse shows a most interesting series,
of stages, which correspond in part to the ancestral forms which
palaeontology seems to prove to be the line of the descent of our existing
Equidae. This matter has recently been elucidated by Professor Ewart, who
details the following facts and comparisons:--

In the youngest embryo (about 20 mm. in length) the humerus is somewhat
curved, and considerably longer than the radius and carpus taken together.
The first-named bone is shorter in the adult, and the proportions of that
bone in the young as well as its curvature are suggestive of that ancient
{250} Ungulate _Phenacodus_ (see p. 202). In the next stage (an embryo of
25 mm.) the humerus has slightly decreased in proportionate length, and has
come to be more like that of _Hipparion_. In both of these embryos it
should be noted that the ulna is complete and separate from the radius. In
the second of the two it has more distinctly acquired the form which it
will possess in the adult. The second metacarpal--one of the splint bones
of the adult--is tipped with a small nodule of cartilage, which is clearly
the representative of one or more of the phalanges belonging to that digit.

FAM. 2. TAPIRIDAE.--The Tapirs may be distinguished from the Horse and from
the Rhinoceros tribe by a few characters, which are as follows:--

The dentition is generally the full one of forty-four teeth. The premolars
in the more ancient forms are unlike the molars, but like them in more
recent forms. The molars of the upper jaw have two crests parallel and
united by an outer crest. The fore-feet have four, the hind-feet three
toes.

The family is fully as ancient as that of the Equidae, but the
specialisation of the toes never advances so far. The modern
representatives of the order are, so far as the feet are concerned, in the
condition of very early representatives of the equine stock. Nor do the
teeth of the Tapirs ever reach the complicated pattern of that presented by
at least the modern Horses, or indeed of the Palaeotheres. Apart from this
it is not an easy matter to distinguish accurately between these several
families, including the Lophiodontidae, which, as already mentioned, is
placed nearer to the Tapiridae than to the Palaeotheriidae. Indeed the
differentiation of these two families, the Tapiridae and the
Lophiodontidae, seems to be a matter of the greatest difficulty. The
difficulty is well emphasised by the fact that naturalists disagree most
profoundly as to the relations of various genera of extinct Tapir-like
animals. For Mr. Lydekker the genus _Lophiodon_ includes also the American
genera _Isectolophus_ and _Systemodon_, which are placed by Zittel in the
sub-family Tapirinae as opposed to Lophiodontinae, which contains
_Lophiodon_ and _Helaletes_. The existing Tapirs can be differentiated from
the existing Horses with great ease, as the following account of the
existing genera will show.

{251} [Illustration]

FIG. 128.--American Tapir. _Tapirus terrestris._ × 1/10.

The genus _Tapirus_ is now met with only in South and Central America, and
in the Malay Peninsula and the islands of Java and Sumatra. This animal is
in many respects the most ancient of existing forms referable to the
Perissodactyle order. It has four toes on the front-feet, though only three
on the hind-feet. The number of teeth is 42--nearly the typical Eutherian
number. The Tapirs are always moderately-sized animals, entirely covered
with hair, and usually of a brownish-black colour. The Malayan Tapir is,
however, banded broadly with white--a single band; the young of the Tapir
is spotted, and striped with white. The nose and upper lip conjoined are
produced into a short trunk, precisely comparable with that of the
Elephant. As in the Rhinoceros--and in this both contrast with the other
existing Perissodactyle genus _Equus_--the temporal fossa is not separated
from the orbit by bone. Of existing Tapirs there are at any rate _T.
terrestris_,[163] _T. roulini_ (the "Tapir Pinchaque" of Cuvier), _T. dowi_
and _T. bairdi_ in America (the last two being sometimes separated into a
distinct genus, _Elasmognathus_, on account of the prolongation of the
ossified mesethmoid), and _T. indicus_ in the East. The tapir, probably _T.
terrestris_, is described by Buffon as "a dull and gloomy animal." It is
certainly mainly nocturnal in habit. The name _terrestris_ was given by
Linnaeus, who placed it in the same genus as {252} _Hippopotamus
amphibius_; hence the epithet applied to the Tapir. But as a matter of fact
it loves marshy neighbourhoods, and is in a way amphibious. This does not
of course apply to the Andesian _T. roulini_, which inhabits the cordillera
of Ecuador and Colombia. The distribution of existing Tapirs is, as is so
often the case, restricted when compared with that of their extinct
congeners and allies. In Europe the remains of the genus _Tapirus_ are
abundant from Pliocene strata, and its remains are there known from as far
back as the Miocene. The genus is thus one of the very oldest forms of
Mammalia at present inhabiting the earth.

[Illustration]

FIG. 129.--Malayan Tapir. _Tapirus indicus_, young. × 1/10. (From
_Nature_.)

The Malayan Tapir is to be distinguished from the American (_T.
terrestris_--the other species have not been dissected) by the greater
development of the valvulae conniventes in the intestine, the absence of a
moderator band in the heart, and the less elongated caecum, which is
sacculated by only three bands, there being four in _T. terrestris_.[164]
The animal frequents the most retired spots among the hill woods, by which
habit it seems {253} largely to escape the Tiger, its most formidable foe
in those regions of the world. Its quickness of senses enables it also to
slip away with rapidity. It can proceed at a great pace when disturbed, and
can readily push its way through obstacles. The young animal, like that of
the American species, is dark brown with yellowish spots. It is stated by
Mr. H. N. Ridley that the young animal lies during the hot part of the day
under bushes, in which situation "its coat is so exactly like a patch of
ground flecked with sunlight that it is quite invisible." It is interesting
to note that here, as with some other animals, it is the young that are
especially protected by such mechanisms. Moreover, some of the spots are
round and some are more elongated, so that the resemblance to spots of
sunlight which come in a direct and in a slanting direction is greatly
increased. Even the colours of the adult are not so conspicuous when it is
in its native haunts as might be supposed. The breaking up of the ground
colour into tracts of two different colours prevent it from striking the
eye so plainly as if it were of one colour throughout. "When lying down
during the day it exactly resembles a grey boulder, and as it often lives
near the rocky streams of the hill jungles, it is really nearly as
invisible then as it was when it was speckled."[165]

FAM. 3. RHINOCEROTIDAE.--This family is to be distinguished from the
preceding by a number of characters, which though not universal are
general. In the first place, there are commonly horns, or a horn,
consisting of what appears to be an agglomeration of hair-like structures
fixed upon a roughened patch of bone on the surface of the nasals. The
incisors are diminished or defective, and the upper canines are often
wanting. The molars and premolars are alike. The fore-feet are four- or
three-toed, but are functionally tridactyle; the hind-feet are three-toed.
The skeleton in this family is massive, and the limbs relatively short. The
skull, as in the Tapirs, has a confluent orbit and temporal fossa. The
upper lip is generally more or less prehensile; the body is as a rule--to
which the Pleistocene Hairy Rhinoceros is of course an exception--rather
sparsely covered with hair. In this feature the Rhinocerotidae contrast
both with the Tapiridae and the Equidae. The family in reality contains but
one existing genus, though three have been instituted, viz. {254}
_Rhinoceros_, _Ceratorhinus_, and _Atelodus_. As there are so few existing
species the subdivision of animals which agree in so many and such
highly-characteristic features seems to be an unnecessary procedure. The
existing Rhinoceroses are but a fragment of the total number of known forms
from past epochs. The family is very markedly on the wane.

The genus _Rhinoceros_ is characterised by its heavy build and thick,
almost smooth, skin--smooth, that is to say, so far as concerns the slight
development of hair--which is often thrown into folds. There is one or
there are two horns on the fore-part of the head, which are, as has already
been pointed out, structures _sui generis_, and not exactly comparable with
the horns of other living Ungulates. There are three nearly equal toes on
both fore- and hind-limbs. The canine teeth of existing species have
disappeared; the incisors are, or are not, present; the molars and
premolars are three and four in each half of each jaw.

The visceral anatomy of the Rhinoceros has been much investigated so far as
concerns the Asiatic forms. A curious feature, which serves to discriminate
some of the Asiatic species from others, is to be seen in the small
intestine. In _Rh. indicus_[166] this gut is furnished with numerous long
cylindrical narrow outgrowths "like tags of worsted"; in the allied _Rh.
sondaicus_ these tags are present, but are flatter and broader; while in
the two-horned _Rh. sumatrensis_ there are no tags at all, but only smooth
valve-like folds. Another mark by which these species can be distinguished
depends upon the variation in the presence or absence of certain glands
imbedded in the integument of the foot--the so-called "hoof glands." These
occur in _Rh. indicus_ and _Rh. sondaicus_, but are absent in _Rh.
sumatrensis_.

Sir W. Flower[167] studied some years since the skull features which serve
to differentiate the existing forms.

In _Rh. sumatrensis_ the two long downward processes of the squamosal bone,
termed respectively post-glenoid and post-tympanic, do not unite below the
auditory meatus. In this the species in question agrees with the African
forms but not with the one-horned Asiatic species, where the two processes
completely fuse. Again, another character, though perhaps less important,
{255} is the sloping backwards instead of forward of the occipital crest in
all two-horned species, whether African or Asiatic.

The Asiatic Rhinoceroses have, what the African animals have not,
functional incisor teeth throughout life. It has been proposed on these and
other grounds to separate generically the African and Asiatic forms.

[Illustration]

FIG. 130.--Indian Rhinoceros. _Rhinoceros indicus._ × 1/40.

The Asiatic Rhinoceroses include three well-differentiated species, in all
of which the skin is much thrown into folds. _Rh. indicus_ is the largest
form. It is one horned, and has enormous folds of skin at the neck and
hanging over the limbs. So like artificial armour is this thick plating,
that Albrecht Dürer may be excused for having given the beast the
appearance of being actually mail-plated in a sketch which he made of a
specimen sent over to the King of Portugal in 1513. This particular beast,
one of if not the first sent over to Europe, proved so intractable in
disposition that the king sent it as a present to the Pope. But "in an
access of fury it sunk the vessel on its passage"! The horn of this and of
other species was held until almost our times to have medicinal and other
more curious values. So recently as 1763 it was gravely asserted that a cup
made of its horn would fall to pieces if poison were poured into it. "When
wine is poured therein," wrote Dr. Brookes in the year referred to, "it
will rise, ferment, and seem to boil; but when {256} mixed with poison it
cleaves in two, which experiment has been seen by thousands of people."
John Evelyn also wrote of a well in Italy which was kept sweet by a
Rhinoceros' horn. This species seems to be long-lived, even in captivity; a
specimen now to be seen in the Zoological Society's Gardens has been there
since the year 1864.

_Rhinoceros sondaicus_, the Rhinoceros of the Sunderbunds, has a much wider
range than the last species or Indian Rhinoceros. This is unknown out of
India itself, and is there limited to a small region; the Sondaic form is
found in Bengal and in the Malayan Islands. It is a smaller species, and
the armour has a tesselated appearance. The female generally, if not
always, is hornless.

[Illustration]

FIG. 131.--Sumatran Rhinoceros. _Rhinoceros sumatrensis._ × 1/15. (From
_Nature_.)

The Sumatran species, _Rhinoceros sumatrensis_, is to be distinguished from
the last two by its two horns. It is also covered {257} by a much thicker
coat of hairs, which are sometimes blacker and sometimes redder. On account
of its two horns it has been proposed to separate it from the other
Oriental species into a distinct genus, _Ceratorhinus_. The animal has much
the same range as the last species, but extends to Borneo. A variety of
this species with hairy ears, from Assam, has been separated as a distinct
form, under the name of _Rh. lasiotis_, by Mr. Sclater. The animal upon
which that species was founded was until quite recently living in the
Zoological Society's Gardens.

[Illustration]

FIG. 132.--Hairy-eared Rhinoceros. _Rhinoceros lasiotis._ × 1/30.

There are only two certainly-known species of Rhinoceros in Africa. These
are the White Rhinoceros (_Rh. simus_) and the Black Rhinoceros (_Rh.
bicornis_). The origin of the names is not easy to understand, since the
"white" animal is, if anything, darker in colour than the Black Rhinoceros.
It is stated, however, that in past years the specimens of _Rh. simus_
found in the south-west of Cape Colony were "paler and whiter in colour
than those in the north-east." At present there are no grounds for
distinguishing the species by their colour characters. But they are plainly
distinguishable on other grounds. _Rhinoceros simus_ has a square upper
lip, and in relation to this crops the herbage upon the ground. _Rh.
bicornis_ has a prehensile upper lip projecting beyond the lower, and in a
corresponding fashion feeds principally upon the branches of shrubs, It has
been pointed out by Mr. {258} Coryndon[168] that the calf of _Rh. simus_
"always runs in front of the cow, while the calf of _Rh. bicornis_
invariably follows its mother." Both animals of course have two horns, and
upon the varying proportions of the horns a large number of "species" have
been made in the past. It is stated that the longest horn of the "White
Rhinoceros" known measures 56½ inches; while that of _R. bicornis_ is
shorter, 40 inches being apparently the maximum. But the animal is smaller.

[Illustration]

FIG. 133.--Head of _Rhinoceros bicornis_.

The possible third African species of _Rhinoceros_[169] has been
provisionally named after Mr. Holmwood, and is based upon two horns 41 and
42 inches long, which may be abnormal horns of _Rh. bicornis_; but they are
thinner and have a smaller pedicel.

EXTINCT RHINOCEROTIDAE.--The existing Rhinoceroses are thus confined to
Africa, to certain parts of the continent of Asia, and to some of the large
islands lying to the south of that continent. But formerly the genus, and
allied genera, had a wider range. As far back as the Miocene we meet with
remains of Rhinoceroses closely allied to existing forms. The more ancient
forms have, as is natural, more ancient characters. Thus in _Rh.
schleiermacheri_ of the Miocene, canines appear to have been present. The
Miocene _Aceratherium_, primitive in the absence of horns as its {259} name
denotes,[170] had also canines and, in one species, six incisors in the
lower jaw. This _Aceratherium_ had, moreover, four toes in the fore-feet.
In the Miocene and later the Rhinoceros existed in Europe and America.
There was even a purely northern form, the _Rh. tichorhinus_, which
possessed a woolly covering and had the same range as the Mammoth. This
Rhinoceros was two-horned.

The post-Pliocene and European _Elasmotherium_ was a colossal rhinocerotine
creature. This great beast had two horns and a body 15 feet long. Its limbs
are not known, and as the teeth are different from those of Rhinoceroses in
general, it may not have belonged to this group at all, though Osborn is
inclined to derive it from _Aceratherium_, admitting at the same time that
the evidence is "decidedly slender." The teeth in fact are like those of a
Horse in being hypselodont and prismatic in form. As to the two horns, they
were apparently not exactly like those of typical Rhinoceroses; there was
an enormous horn posteriorly, supported on a huge boss of bone, and in
front of this a roughened spot suggests a smaller or at least a much more
slender horn.

It is important to notice that fossil Rhinoceroses belonging to the
restricted genus _Rhinoceros_ were in Europe invariably two-horned; it is
only in India, where they still exist, that one-horned forms are met with
in a fossil state.

[Illustration]

FIG. 134.--Skeleton of _Hyracodon nebrascensis_. × 1/12 (After Scott.)

The Rhinoceroses of America were mostly hornless. _Diceratherium_ is an
exception; but in many cases it had two parallel not successive horns, and
these were, to judge from the slight prominences, but feeble in
development, and perhaps hardly exactly comparable with the formidable
weapons of the Old-World forms. _Aceratherium tridactylum_, with
indications of paired horns, may be ancestral to _Diceratherium_. The
American forms have weak and slender nasals in correspondence with the
absence of horns; the sagittal crest is retained in contradistinction to
the great flattened surface of the skull in the horned Rhinoceroses.
_Aceratherium_ of both divisions of the globe probably represents the
ancestral group of the horned and the hornless forms. This being the case
it is highly interesting to note a distinct convergence in the quite {260}
separate American genera towards the European horned genera. A genus
sometimes united with _Aceratherium_, but still differing from it in some
points, is _Aphelops_ (_Teleoceras_).[171] This animal is more nearly
approximated to "the modern standard" of Rhinoceroses than is its possible
ancestor _Aceratherium_. The skeleton in general is more robust, even
surpassing that of modern forms, and approaching the _Hippopotamus_. There
is a reduction in the upper incisors, which are limited to two pairs, and
the lower molars {262} are reduced to five. The lower incisors are only
two. The sagittal crest is less marked; the fifth digit is reduced to a
tiny nodule representing the metacarpus. It had a small nasal horn. There
are numerous other details of likeness to modern Rhinoceroses in this
creature, which has only community of descent with them from the older
hornless forms, such as _Aceratherium_ and _Caenopus_. In the genus
_Peraceras_ the upper incisors are as completely gone as in the living
African Rhinoceroses.

[Illustration]

FIG. 135.--Skeleton of _Aphelops (Teleoceras) fossiger_. × 1/15. (After
Osborn.)

The most ancient rhinocerotine types[172] are the Hyracodonts and the
Amynodonts. They both date from the Eocene, and became extinct in the
succeeding Oligocene. _Hyracodon_[173] (Fig. 134) was "an agile,
light-chested, and rather long-necked" type, resembling a Horse in build.
There were no horns present, but the hoofs were more like those of the
Horses than of the existing Rhinoceroses. These animals were apparently
plain dwellers and defenceless, which is held to account for their compact
hoofs and outward similarity to a Horse. The genus is Oligocene. The dental
formula is I 3/3 C 1/1 Pm 4/3 M 3/3.

It is surmised by Professor Scott that the number of dorso-lumbar vertebrae
was twenty-three or twenty-four. The radius and ulna are complete and
separate bones, but the latter is somewhat reduced. There are four
metacarpal bones, of which, however, the fifth is much reduced. The animal
is only three-fingered. The tibia and the fibula are distinct, and show no
tendencies towards fusion; but the fibula is much reduced. There are only
three metatarsals and three toes. Had this line, which is to be regarded as
a side branch of the Rhinoceros stem, not died out, it would probably have
resulted, thinks Professor Scott, in monodactyle--very Horse-like types. It
is later than the next genus to be described, _Hyrachyus_, of which it is
possibly a descendant. An intermediate type, _Triplopus_, appears to bind
together _Hyracodon_ and _Hyrachyus_.

In _Hyrachyus agrarius_ the skull is long and narrow, the facial region
being markedly longer than in existing Rhinoceroses. The mastoid portion of
the periotic bone is widely exposed upon the outer face of the skull, which
is, as has been said, not the case with the existing genus _Rhinoceros_.
The dentition is the complete Eutherian dentition of forty-four teeth. The
upper {263} molar teeth are strikingly like those of the genus
_Rhinoceros_. The fore-feet are pentadactyle, but functionally
tetradactyle; the hind-feet tridactyle. The ulna is less reduced than in
_Hyracodon_, and the dorso-lumbar vertebrae are twenty-five.

[Illustration]

FIG. 136.--Skeleton of _Metamynodon planifrons_. × 1/22. (After Osborn and
Wortman.)

The Amynodonts were short, heavy types, probably marsh-haunting in habit,
and possibly with a proboscis like that of the Tapir. The orbit is higher
than it is in the purely terrestrial {264} Hyracodonts, and it is suggested
that when swimming it was raised above the surface as with the
Hippopotamus. "This feature," observes Professor Osborn, "with the long
curved tusks, undoubtedly used in uprooting, suggests the resemblance
between the habits of these animals and those of the hippopotami." There
were no horns in the Amynodonts. The face is shorter than in the
Hyracodonts, and the mastoid is covered as in recent Rhinoceroses. The
canines are very strongly developed into tusks, but the incisors show signs
of disappearance. We know of the genera _Amynodon_, _Metamynodon_, and
_Cadurcotherium_. All except the last, which is European, are American in
range.

FAM. 4. TITANOTHERIIDAE.--These Oligocene Ungulates, often attaining to
large dimensions, are nearly peculiar, so far as is at present known, to
the North American Continent, and are at least most abundant in it.[174]
Many generic names, such as _Titanotherium_, _Brontotherium_, _Brontops_,
_Titanops_, and _Menodus_, have been given to them; but a recent study of
the entire material accessible for description or already described has led
Professor Osborn to the opinion that there was but a single genus, to which
the name _Titanotherium_ must be applied. Of this genus there are some
thirty well-characterised species, of which the gradual evolution can be
traced from the lowest strata of the White River beds where their remains
occur. An entire skeleton of _T. robustum_ enables us to understand the
osteology of these forms and to compare them with other Perissodactyles.
This animal was more than 13 feet long, standing some 7 feet 7 inches in
height. It seems to have presented during life the aspect of a Rhinoceros
with perhaps a touch of Elephant. The skull is not unlike that of a
Rhinoceros in general dimensions and shape; but there are a pair of
apparent horn cores anteriorly, which are smaller in the more ancient forms
and acquire a large size, a forward direction with a divergence of the two
in the later forms. A glance at the accompanying figures of skulls (Fig.
137) of early and later Titanotheres will exhibit the changes in this
particular which the skulls underwent in the lapse of time occupied by the
deposition of these Oligocene beds. The nasals are short in the later,
longer in the more early species, such as _T. heloceras_ and _T.
coloradense_. The zygomatic arch projects much, and is "shelf-like" in the
later forms, the skull thus getting an immense breadth, which, {266}
together with the long and divergent horn cores, must have given to the
living animal a most bizarre appearance. It is an interesting fact that
this animal, though a Perissodactyle, agrees with the Artiodactyla in the
nineteen dorso-lumbar vertebrae, of which seventeen bear ribs.

[Illustration]

FIG. 137.--Three figures showing the cranial evolution of _Titanotherium_.
Upper figure, _T. trigonoceras_; middle figure, _T. elatum_; lower figure,
_T. platyceras_. (After Osborn.)

The genus further agrees with the Artiodactyles in the structure of the
carpus. The toes of the fore-limb are four, those of the hind-limb three;
but while the hind-limb is undoubtedly Perissodactyle in the arrangement of
its component parts, the fore-limb shows a hint of an Artiodactyle mode of
structure. This limb is paraxonic, the axis of the limb passing between the
two middle digits. It may be that this genus represents more nearly than
any other Perissodactyle or Artiodactyle the primitive stem from which both
have diverged, though, of course, it is not old enough to be very near to
the actual ancestor. The molar dentition is the typical one; the incisors
seem to vary as to their presence or absence, and, if present, in their
numbers. In comparing the older with the more recent forms it is noteworthy
that there has been an increase of size exactly as there has been during
the evolution of the Camels and some other groups of Ungulates. As already
mentioned, the size of the horn cores also increases until it culminates in
the extraordinary species, _T. platyceras_ and _T. ramosum_, in which these
are half as long as the skull, flattened in form, and connected at their
bases by a "web" of bone. Arrived at this amount of specialisation the
genus _Titanotherium_ apparently exhausted its capacities for modification
and ceased to be. The many generic names may be explained by sexual
differences on the one hand and an incomplete knowledge of connecting links
on the other.[175]

_Palaeosyops_ is somewhat like a Tapir in build, the skull especially
resembling that of the Tapir. As in _Titanotherium_ the molar teeth,
instead of having an outer wall formed by fused cusps, have a [176]-shaped
outer wall on one side and two or one cusps on the opposite side. It is,
moreover, an Eocene form, and in correspondence with its greater age is
more primitive in some points of structure, for example, in the absence of
horns and in the full dental formula. The fore-limbs are four-toed, the
hind {267} three-toed. It was intermediate between a Tapir and a Rhinoceros
in size. It has been shown, too, from casts of the interior of the skull,
that the cerebral hemispheres are much less convoluted than were those of
_Titanotherium_.

Related to _Palaeosyops_ is another primitive Titanothere, the genus
_Telmatotherium_. This is also Eocene, from the Uinta Basin, the uppermost
of Eocene strata. The skull of these creatures was rather elongated, and
not unlike that of a Titanothere in general aspect. The dentition was
complete and the canines not very large. The horns, which acquire so
prodigious a development in the later Titanotheres, are just recognisable
in at any rate many species of this genus _Telmatotherium_, the name being
thus by no means an apt one. Better was that proposed by Dr. Wortman, of
_Manteoceras_ or "prophet horned." The horns are small elevations upon the
frontals just at the junction of these with the nasals, and, indeed, lying
partly upon the latter bones. In _T. cornutum_ the horns are chiefly borne
upon the very long nasals, whose size contrasts with the same bones in the
more highly-developed _Titanotherium_. It appears to be quite possible that
_Titanotherium_ was evolved from the genus _Telmatotherium_.[177]

SUB-ORDER 9. LITOPTERNA.

Whether the MACRAUCHENIIDAE should be considered as a separate group of
Ungulata is a matter of dispute. Cope placed them in a special order of
Ungulates which he called Litopterna. Zittel, on the other hand, regards
them as definitely Perissodactyles. One curious point of resemblance to
existing Horses is shown--that is the presence of a pit in the incisor
teeth. This matter seems to be so important as to need a placing of these
forms in the neighbourhood of the Perissodactyles, even of the Equidae; it
is so peculiar a character, and apparently so little related to any obvious
similarity in way of life, that it seems to mark a special affinity. Not so
the fact that in _Macrauchenia_ at any rate the orbit was entirely
surrounded by bone as in the Horse. We find that condition so frequently
acquired in many groups,--a development from an earlier condition where the
cavity for the lodgment of the eye is in continuity with the temporal {268}
fossa, that it cannot be regarded as anything more than a mark of
specialisation. It is, in fact, the case that the Macraucheniidae are in
many points specialised, while retaining many primitive features of
structure.

The chief primitive features are: the non-alternating positions of the
wrist- and ankle-bones; these, of course, interlock in the Perissodactyles
of to-day and in many extinct families. Then the absence of a diastema in
the tooth series, coupled with the presence in _Macrauchenia_ of a complete
dentition. The small brain may be referred to the same category.
_Macrauchenia_ must have been a strange-looking animal. It walked upon
three toes on each limb; the skull was Horse-like in general form, but the
nostrils are removed to a point about as far back as in the Whales or
nearly so, the nasal bones being correspondingly reduced. This it is
thought argues a proboscis. The humerus is particularly compared by
Burmeister[178] to that of a Horse. The radius and ulna though both well
developed are fused. The neck is long, and, as in the Camel, the vertebral
arteries run inside the neural arches. Since the fore-legs seem to have
been rather longer than the hind-legs, though only very slightly, and the
neck was long, the animal may have presented some likeness to the Giraffe.
It is interesting to note that in the proportions of humerus to ulna this
animal is more Lama-like than Horse-like. On the other hand, the
proportions of femur to tibia are more Horse-like. The remains of the
creature are limited to South America, and to quite superficial deposits.
It is evidently a specialised type, and has pursued a course parallel to
that of the Horse. Much nearer to the Horse however, but apparently by
convergence only, is the genus _Thoatherium_, usually placed in a separate
family, the PROTOROTHERIIDAE. In this creature, which has many archaic
characters, the toes are reduced to one in each foot. In an allied form,
_Protorotherium_, we have the two lateral toes diminishing just as in
_Anchitherium_.

       *       *       *       *       *


{269}

CHAPTER XI

UNGULATA (_continued_)--ARTIODACTYLA (EVEN-TOED UNGULATES)--SIRENIA

SUB-ORDER 10. ARTIODACTYLA.

[Illustration]

FIG. 138.--Bones of the Manus--A, of Pig (_Sus scrofa_). × 1/3. B, of Red
Deer (_Cervus elaphus_). × ½. C, of Camel (_Camelus bactrianus_). × 1/8.
_c_, Cuneiform; _l_, lunar; _m_, magnum; _m_^2, _m_^5, second and fifth
metacarpals; _R_, radius; _s_, scaphoid; _td_, trapezoid; _u_, unciform;
_U_, ulna; _II-V_, second to fifth fingers. (From Flower's _Osteology_.)

The Artiodactyle or "Even-toed" Ungulates are to be distinguished from the
Perissodactyla, and from other Ungulate groups, by a number of trenchant
characters. The most salient {270} of these, and that which has given its
name to the group, concerns the arrangement of the digits. Instead of there
being but one prevailing digit--the third, in the hand and foot, through
which the axis of the foot passes, there are two, numbers three and four,
between which the same axis passes, and which are perfectly symmetrical
with each other. This type of foot has been termed "paraxonic," as opposed
to the "mesaxonic" Perissodactyle foot (see Fig. 121 B, p. 235). It has
been attempted to prove that the single prevailing digit of the Horse's
foot is a fused pair of digits, and the state of affairs which
characterises the Camel, where the two metacarpals or metatarsals are to an
almost complete extent united, has been urged in proof; so, too, certain
abnormalities, such as those called "solid-hoofed pigs."[179] These latter
are simply Pigs in which the two central metacarpals and the terminal hoofs
are completely fused with one another. In some of such cases there is not
the slightest trace of the union of the separate metacarpals and phalanges.
Even the sesamoid bones, attached behind to the toes, are two in number
instead of four. And, furthermore, the tendon supplying the bones is
single, though showing traces of its double origin. Such Pigs often show
the abnormality from generation to generation, and they proved convenient
for those whose scruples would not allow them to eat the flesh of a beast
"dividing the hoof" and not chewing the cud. More singular still, as
showing a pathological approach from another side to the Perissodactyle
condition in an Artiodactyle, is a calf, where the foot ended in three
equi-sized digits, of which the middle one lay in the longitudinal axis of
the limb. From the opposite side cases are known of a Horse with a split
hoof and phalanges, thus presenting the most striking likeness to a Camel.

There is, furthermore, in certain groups of Artiodactyles (_e.g._ the
Tragulidae) a tendency for the two middle metacarpals to unite, quite apart
from such "sports" as those illustrated by the cases just set forth. And,
as already mentioned, the union of the two middle metacarpals culminates in
the Camel, Ox, etc. There is, however, absolutely no trace of such a fusion
in the series of Perissodactyle animals known to us; and it would be by
fusion rather than dismemberment that, as it would appear on this theory,
the modern Ungulate foot has been arrived at. Of course {271} the facts of
Ungulate descent are absolutely destructive of any such comparisons.

As is the case with the Perissodactyles, the Artiodactyles show a
historical series, the primitive five-toed condition being almost preserved
in _Oreodon_, up to the most modern modification exemplified by the Ox,
Sheep, etc., in which animals there are not even vestiges of the fourth and
fifth toes. It has been stated, however, that the foetal Sheep has traces
of those rudiments. The so-called cannon bone (the fused third and fourth
metapodia) is accompanied in its fusion by an increase in length. At the
same time the functional middle metacarpals push aside the rudiments and,
forming a broad surface for that purpose, articulate with the magnum and
unciform bones to the exclusion of the rudiments. This has been termed an
"adaptive reduction." In the "inadaptive reduction" there is the same
reduction of the metacarpals, but the rudiments still articulate as in the
primitive Artiodactyle foot, _i.e._ Mc II with trapezium, trapezoid, and
magnum; Mc III with magnum and unciform; Mc IV and V with unciform. This
would appear to give greater solidity and consequently greater strength to
the foot.

[Illustration]

FIG. 139.--Dorsal surface of right tarsus of Red Deer (_Cervus elaphus_). ×
1/3. _a_, Astragalus; _c_, calcaneum; _c_^3, cuneiform; _cb_, cuboid;
_mIII_, _mIV_, metatarsals; _n_, navicular. (From Flower's _Osteology_.)

The carpal bones of the Artiodactyla alternate in their articulation; the
primitive state of affairs[180] is not retained even in the earliest types.
The femur has no third trochanter, so prevalent in the Perissodactyles. In
the hind-foot the calcaneum has an articular facet for the fibula, which is
not characteristic of the Perissodactyla. In the more modern forms, _e.g._
the Cervidae, the navicular and cuboid become fused into one bone; and
there are even further fusions which will be referred to later as
characteristic features of different groups. It is interesting to notice
that the reduction begins earlier and is clearer in the hind-foot than in
the fore. One {272} can see how this may be purely adaptive, the push of
the hind-legs in running needing a firmer support. In _Hyomoschus_ this is
the case. The hind-limbs are provided with a cannon bone, while the
metacarpals of the fore-feet are still free.

The number of dorso-lumbar vertebrae is less in the Artiodactyle than in
the Perissodactyle Ungulates. Whereas the former have but nineteen, the
latter have, as a rule, twenty-three such vertebrae.[181] The number of
ribs varies from twelve (_Camelus_, _Hydropotes_) through thirteen
(_Cervus_, _Gazella_) to fourteen in _Dicotyles_, _Giraffa_, etc.

The curious form of teeth known as "selenodont" is characteristic of the
Artiodactyla, though only found well developed in the modern forms, and of
those only in the Pecora. The more primitive forms had "bunodont" teeth
with typically four tubercles (if we except the tritubercular and but
little-known _Pantolestes_); and the intermediate "buno-selenodont" type
characterises such groups as the Anthracotheriidae.

While the stomach of the Perissodactyles is always a simple sac, it is
complicated, or shows signs of complication, in the Artiodactyles. That of
the Hippopotamus is divided into two chambers; there are three in
_Tragulus_, and four in the typical Ruminants such as _Cervus_, _Ovis_,
etc.

Had we to deal only with the still living genera of Artiodactyles, it would
be easy to sort them into two groups on the characters of the teeth; for
the Pigs and Hippopotamus are provided with tubercular molars; they are
bunodont. The Deer, Camels, Oxen, Giraffes, etc., have selenodont molars.
Besides, the latter are "Ruminants," and have a more complicated stomach.
The existing Chevrotains forbid a more trenchant division, since they are,
as will be pointed out in due course, somewhat intermediate in structure;
the feet are more Pig-like, and the stomach is not so typically Ruminant.
In any case such a division is prevented by certain extinct families which
are perhaps ancestral to both. They have teeth which are not quite bunodont
and not quite selenodont. These teeth have been termed buno-selenodont or
buno-lophodont.

The distribution of the living Artiodactyles presents us with some
interesting facts. The vast preponderance of species occurs in the Old
World--34 in America as against over 250 species {273} in Europe, Asia, and
Africa. The Neotropical region has no Oxen, or Sheep, or Antelopes. The
latter are confined to Africa, Asia, and certain parts of the Palaearctic
region; they are vastly more prevalent in Africa, where they take the place
of the totally absent Deer. The Pig tribe is almost entirely Oriental and
Ethiopian in distribution, only one form, the European Wild Boar, ranging
into the Palaearctic region; and the two species of Peccary are found in
both North and South America. Broadly speaking, the Ethiopian region is the
headquarters of the Artiodactyla. But the great island of Madagascar has
but one form of Artiodactyle, a Pig of the genus _Potamochoerus_.[182]

GROUP I.--_SUINA._

FAM. 1. HIPPOPOTAMIDAE.--The family Hippopotamidae contains of existing
genera only _Hippopotamus_, for the Liberian dwarf Hippopotamus is not now
regarded, as it was formerly, as the type of another genus, _Choeropsis_.
The reasons for its former separation were the loss of the outer pair of
incisors and the different proportions of various parts of the skull. This
little Liberian animal has, however, been shown by Sir W. Flower[183] to
possess the missing incisors occasionally; and as to the proportions of the
skull, it is exceedingly common for small animals to vary from larger
relatives in this way. Hence, considering the characteristic features of
the Hippopotamus and the fewness of species, it seems unnecessary to divide
it up further. We shall therefore only recognise one genus.

The Hippopotamus at present is African in range, and confined to that
continent. But quite recently it inhabited Madagascar; and further back
still in time the existing African species, _H. amphibius_, ranged into
Europe; there were also Indian forms, which were contemporary with the
Stone-age man. The Common Hippopotamus is a great thick-skinned beast with
but few hairs. It has four toes on each foot, a complex stomach, but no
caecum. The strong incisors continue growing through life, as do the great
canines. The number of incisors is two on each side of each jaw. Some of
the extinct species had six in each {274} jaw, and they were distinguished
as a genus _Hexaprotodon_, contrasting with _Tetraprotodon_, until
intermediate conditions were observed. _Choeropsis_, as already observed,
was a still further reduction of the tetraprotodont type. The molars (the
formula is Pm 4/4 M 3/3) when worn show a double trefoil pattern. The
orbital cavity is encircled by bone. As with many other aquatic mammals the
kidneys are lobulated.

[Illustration]

FIG. 140.--Hippopotamus. _Hippopotamus amphibius._ × 1/40.

A very singular fact about the Hippopotamus is the production of a "bloody
sweat," a carmine-coloured secretion, containing small crystals and
corpuscles, from the skin. This coloured fluid has of course nothing to do
with blood.[184]

The animal grows to a length of at any rate 14 feet. The limbs and the tail
are short. Like other aquatic animals the nostrils are on the surface of
the head, and can be closed when the animal is under water. When it reaches
the surface of the water after a prolonged immersion, it spouts like a
Whale. Sir Samuel Baker says that ten minutes is the longest time that the
Hippopotamus can remain below the water. It is frequently a dangerous
animal to encounter, as it will capsize boats, and even bite large pieces
out of their bottoms; with its huge teeth it {275} can and does attack and
destroy human beings. The Hippopotamus not only swims, but can walk along
the bottom of a river with great rapidity. It occasionally puts out to sea
from the mouths of rivers frequented by it; and it is supposed that in this
way Madagascar was populated with Hippopotamuses, whose remains are now
found in swamps in that island.

[Illustration]

FIG. 141.--Wild Boar. _Sus scrofa._ × 1/12.

FAM. 2. SUIDAE.--The Pig family, Suidae, differ from the last in their
smaller size, in the terminal nostrils and mobile snout, which is not
grooved, except faintly as in _Babirusa_. They are generally hairy, but the
Babyroussa is an exception, while _Phacochoerus_ is but slightly haired.
Though there are four digits, as in the Hippopotamus, only two reach the
ground in walking. The stomach, furthermore, is simple, and (except in
_Dicotyles_) there is a caecum. The kidneys are smooth, and the liver is
more lobate than in _Hippopotamus_. The orbital cavity is confluent with
the temporal fossa. The typical genus, _Sus_, is distributed over Europe,
Asia, and the islands of the Malay Archipelago, reaching as far as Borneo
and Celebes. The dentition[185] is complete. A single species, the
so-called _S. sennaariensis_, is from Ethiopian Africa, but it is not
certain how far this animal may be an escaped species introduced by man. A
very large number of "species" of _Sus_ have been described, but Dr.
Forsyth {276} Major is disposed to reduce them to four if not to fewer
species. He allows the widely-ranging _S. scrofa_, _S. vittatus_, and the
eastern Malayan _S. verrucosus_ and _S. barbatus_.

[Illustration]

FIG. 142.--Pygmy Hog (from _Nature_). _Sus salvania._ × 1/6.

The Pygmy Hog of the Bhotans seems to be not entitled to specific rank,
certainly not to generic (in the opinion of some), though it has been
termed _Porcula salvania_.[186] The Wild Boar of Europe is _Sus scrofa_. It
was formerly quite abundant in this country; not merely are its remains
exhumed from fens, caves and peat bogs, but there is ample evidence of its
continuance down to a comparatively late historic period. Enactments are on
record as to the hunting of these animals; there are places, such as
Boarstall, whose names are clearly derived from the name of the animal,
presumably once a native of the locality; and various documents all show
the presence of the Wild Boar {277} in this country down to so late a
period as the end of the sixteenth century.

[Illustration]

FIG. 143.--Wart Hog. _Phacochoerus aethiopicus._ × 1/6.

The African Wart Hog, genus _Phacochoerus_, is usually regarded as the type
of a distinct genus of Pigs. This animal, "superlatively ugly" with its
huge tusks and great protuberances upon the face, is chiefly to be
distinguished from the genus _Sus_ by these characters, and by the
complexity of the last molar, which, with the tusks, are sometimes in aged
animals the only teeth left. The complete formula is Pm 2/2 M 3/3. There
are two species of this genus, _P. aethiopicus_ and _P. africanus_. When
enraged the Wart Hog is said to carry its tail directly up, and to present
a ludicrous as well as ferocious appearance.

[Illustration]

FIG. 144.--Head of Wart Hog.

The Celebesian Babyroussa, genus _Babirusa_, is an almost hairless hog with
enormously upturned tusks in both jaws of the {278} male. In the Wild Boar
there is a hint of this, which is carried still further in _Phacochoerus_;
but in _Babirusa_ the upper tusks turn upwards before they leave the
substance of the jaw, for which reason they appear to arise on its dorsal
surface; the lower tusks are nearly as long. It has been found that the
young of this Pig are not striped as are those of other Pigs. By means of
the curved upper tusks this animal has been said by old writers to suspend
itself to branches of trees, just as does by his downwardly-projecting
tusks the male Chevrotain! There is but one species, _B. alfurus_.

From _Sus_ proper the African and Malagasy _Potamochoerus_, including the
Red River Hog, is barely separable generically. Their principal claim to
generic distinction lies in the existence of a horny outgrowth arising from
a bony apophysis above the canine in the male. These have been compared to
the osseous "horn cores" in the extinct Dinocerata. But the Javan _Sus
verrucosus_ shows at least the beginning of a similar modification. The
popular name of the animal is derived from the fine rufous colour of its
pelage, not seen, however, in all the species. Dr. Forsyth Major[187]
recognises five species, of which only one is from Madagascar.

[Illustration]

FIG. 145.--Peccary. _Dicotyles tajaçu._ × 1/6.

FAM. 3. DICOTYLIDAE.--The Peccaries are generally placed in a different
family from that of the other Pigs. This family, {279} Dicotylidae,
contains but one genus, _Dicotyles_, with at most two species. The name of
the animal is connected with the dorsal gland; the animal thus appeared to
possess two navels. The Peccaries, exclusively confined to the New World,
differ from the Old-World Pigs in one or more important characters. They
have only three toes on the hind-feet, and the stomach is complicated.
Though the Peccaries have but small tusks they hunt in packs and are very
dangerous animals to meet with. They owe, too, their safety from many foes
to their sociable habits. Being nocturnal animals they are liable to the
attacks of the Jaguar, which will speedily overpower and devour a Peccary
that has strayed from its herd.

FOSSIL SWINE.--The existing genera of the Pig tribe are also known in a
fossil condition. _Sus_ itself goes back as far as the Upper Miocene. _Sus
erymanthius_, the Erymanthine Boar, is known from beds of that age in
Greece, England, and Germany. This genus is not known to have had a wider
distribution in the past than it has in the present. _Dicotyles_ occurs in
the Pleistocene of both North and South America, the regions which it
inhabits at the present day. The genus _Listriodon_, also Miocene, is
remarkable for having lophodont instead of bunodont teeth, that is so far
as concerns the molars, which resemble those of the Tapir. It was European
and Indian in range. A number of genera, more remote from the existing Pigs
than those which have just been dealt with, are placed together in a
special sub-family, Achaenodontinae. The type genus, _Achaenodon_, had a
somewhat short skull for a Pig; and it is in general aspect and in the
characters of the canine teeth highly suggestive of that of a Carnivore.
The bunodont molars, however, are Suine, as is the form of the lower jaw
with a rounded angle. This is an Eocene animal found in Wyoming.

_Elotherium_[188] occurs chiefly in the Miocene of both North America and
Europe; but _E. uintense_ is Eocene. The orbits are completely encircled by
bone in the more modern forms; this is not the case in the last-described
genus, with which _E. uintense_ agrees. The skull is also longer and more
Pig-like. The zygomatic arch is powerful, with sometimes a large descending
process, such as is found in _Diprotodon_, more faintly in Kangaroos, and
in Sloths and certain extinct Edentates. The lower jaw has a pair {280} of
dependent processes near the symphysis, which suggest processes occupying a
corresponding position in _Dinoceras_. The skull and body are heavy, but
the two-toed limbs are slender. There is a smaller pair of toes behind
these. The dentition is complete, and the canines are not inordinately
developed. The brain is very diminutive. Perhaps _E. uintense_ should be
separated as a distinct genus, _Protelotherium_.[189]

_Hyotherium_ (which is regarded as identical with _Palaeochoerus_) has a
sharp sagittal crest; the orbit is nearly but not quite closed. The canines
are not strongly developed. The upper canines have double fangs as in
_Triconodon_ among extinct mammals, and as in the Hedgehog and other forms
among living Mammalia. The premolars have the cutting and serrated edge of
those of some other Pigs, a feature which gives them a curious resemblance
to the "grinding" teeth of Seals. The molars are tuberculate, and like
those of living Pigs. It is European and Indian in range, and Miocene.

The genus _Choeropotamus_ has a complete dental formula save for the loss
of a premolar in the lower jaw. Though it has lost this tooth, it is from
an older stratum than some of those forms which have retained that
premolar; it has been found in the Upper Eocene of the Isle of Wight and of
the neighbourhood of Paris.

The American and Miocene _Chaenohyus_ has lost the corresponding teeth of
the upper jaw.

_Homacodon_[190] is a genus consisting of several species, which has a
bunodont and complete dentition. The molars are sextubercular in the upper
jaw. _H. vagans_ was of about the size of a Rabbit, and it appears to have
had a curved neck. The limbs had five digits, as is so generally the case
with Eocene Ungulates. It is known from the Middle Eocene of Wyoming.

GROUP II.--_RUMINANTIA._

The Selenodontia or Ruminantia form the second division of existing
Artiodactyles. The characters of the teeth, which give them their name,
have already been referred to. They also differ in that there are never
more than a single pair of incisors {281} in the upper jaw, and very
usually there are none. As a general rule the third and fourth metacarpals
and metatarsals become united to form a cannon bone. To this there is but
one exception, the African _Hyomoschus_. Moreover, the second and fifth
digits are nearly always rudimentary, and may practically disappear
altogether. Here again the Tragulidae are an exception. The Ruminantia are
so-called on account of the fact that they "ruminate," that is, after the
food has been rapidly swallowed, it is forced back up the gullet and more
thoroughly masticated. Associated with this is a complex stomach, which is
divided into several compartments. This stomach has at least three
compartments, as in the Tragulidae; but it has usually four. Its characters
are illustrated in Fig. 146. The majority of the Selenodontia possess
horns, which are partly formed of solid protuberances of the frontal bones.
In the Giraffe they are somewhat different.

[Illustration]

FIG. 146.--Stomach of Ruminant opened to show the internal structure. _a_,
Oesophagus; _b_, rumen; _c_, reticulum; _d_, psalterium; _e_, abomasum;
_f_, duodenum. (After Flower and Lydekker.)

This group may be divided into--A. TRAGULINA, Chevrotains; B. TYLOPODA,
Camels, Lamas; and C. PECORA, Deer, Antelopes, Oxen, Giraffes, Goats,
Sheep.

A. TRAGULINA.

As the Tragulina are undoubtedly the most ancient of the Selenodontia it
will be logical to commence with an account of them. {282}

FAM. 4. TRAGULIDAE.--This family comprises a number of small Deer-like
animals, which are really in many points more related to the Pigs than to
the true Deer. They are known as Chevrotains; and the term "Deerlet,"
introduced by Professor Garrod, is certainly appropriate, since they have
the aspect of very small and hornless Deer. If it were not for their
Artiodactyle feet one might at a glance confuse these creatures with some
Marsupial type. The family is Oriental and West African in range. The two
genera (whose individual peculiarities will be considered later) differ
from other Artiodactyles in a number of rather important characters.

[Illustration]

FIG. 147.--Indian Chevrotain. _Tragulus meminna._ × ¼.

They are absolutely hornless in both sexes. The canines are present in both
jaws, and are especially well developed in the upper jaw. The dental
formula is I 0/3 C 1/1 Pm 3/3 M 3/3. In the skull the tympanic bulla is
usually, as in the non-ruminating Artiodactyles, filled with loose bony
tissue. The feet (usually) have the four toes of the Suina, and are
therefore in a more primitive condition than in Deer and Antelopes. But as
the middle metacarpals are fused in _Tragulus_ (though separate in
_Hyomoschus_) they are a stage further than are the Pigs, in the direction
of the typical Ruminants.

The stomach is comparatively simple, thus offering {283} intermediate
characters between the Pigs and the Ruminants; there are but three separate
compartments. A highly-interesting character is afforded by the placenta.
This is in the present family of the diffuse kind, not presenting the
separated and tufted cotyledons of the Ruminant placenta. This we may
fairly assume is a further proof of the less-specialised characters of this
group[191] as compared with the Ruminantia, a view, however, which is not
universally accepted. While the molars have the selenodont character of
other Pecora, the premolars are more adapted for cutting, with sharp edges.

The genus _Tragulus_ consists of several species (e.g. _T. stanleyanus_,
_T. napu_, etc.), which have been aptly compared in external appearance to
certain Rodents such as the Agoutis. The legs are delicate and slender,
hardly "thicker than an ordinary cedar pencil." These creatures have got
among the Malays a considerable reputation for astuteness, embodied in the
saying, "Cunning as a _kanchil_." The male has tusks, which greatly
contributed to the confusion of this creature with the totally different
Musk Deer, _Moschus moschiferus_. It is even said to suspend itself by
their aid to the branches of trees, and so avoid danger.

_Hyomoschus_ (or _Dorcatherium_ as it should properly be called) is West
African. Its rich brown colour, with spots and stripes, is much like that
of the Chevrotains, but it has shorter limbs. The only species is _D.
aquaticum_, which is sometimes called, on account of its frequenting the
banks of streams, the Water Chevrotain. Remains of this genus occur in
Miocene and Pliocene strata of Europe.

The separate metacarpals, comparatively simple stomach, absence of horns,
diffuse placenta, and spotted pelage are features which argue the primitive
position of these animals among existing Artiodactyles.

Besides the two existing genera which have just been treated of, there are
a number of extinct genera undoubtedly belonging to the same group.

_Gelocus_ (Eocene and Oligocene in range) is a European genus known from
France. It differs from the living members of the group by the fact that
the second and fifth toes on both hind- and fore-feet are represented, as
in certain Deer, {284} by rudiments at the upper and at the lower end only;
they are deficient in the middle. The middle large metacarpals, though
closely applied, are not fused. The metatarsals, on the other hand, are, or
are not fused, according to the species. A later form is the genus
_Leptomeryx_ from the Miocene of North America. This genus departs from the
typical Traguline structure in more than one point. The tympanic bulla is
hollow instead of being filled with cancellated bone; the cuneiform is not
fused with the cuboid and navicular, though the latter are with each other;
the lateral digits of the hind-feet are rudimentary. The magnum and
trapezoid, however, are fused. In the fore-feet the middle metacarpals are
separate, and the lateral less perfect metacarpals have toes. The
metatarsals are fused.

Not definitely referable to the Tragulidae, but coming near to them, are
the PROTOCERATIDAE. Of this family there is but one well-known genus,
_Protoceras_,[192] from the Miocene of North America.

The skull is singularly reminiscent of _Dinoceras_, with which this quite
Artiodactyle genus has, of course, nothing to do. It merely exemplifies the
phenomenon of "parallelism." In general form it is peculiarly long and low.
There are three pairs of bony protuberances: one, the largest, pair are
situated on the maxillae rising up just behind the implantation of the
canine teeth; the parietals have a second pair; and a third much more
diminutive pair of bosses are upon the frontals, near their junction with
the nasals. This description refers to the male; the female has only traces
of the parietal bosses. These were all possibly tipped or sheathed with
horn or roughened skin. The dentition of this genus is precisely that of
the Tragulidae, _i.e._ I 0/3 C 1/1 Pm 4/4 M 3/3. The orbit is completely
encircled by bone; the auditory bulla is not swollen; the premaxillae are
small.

The nasal cavity is very large and open, the end of the nasal bones
anteriorly being situated at about the middle of the skull; this would seem
to indicate at least a flexible and long nose like that of the Saiga
Antelope, if not a trunk.

The brain was of good size, and quite well convoluted.

The limbs are constituted on the Traguline plan; in the fore-limbs the
middle metacarpals are quite free from each other, and the more diminutive
lateral digits are complete. The {285} metatarsals are free, but with a
tendency to fusion; the lateral toes are only represented at the upper
extremity. The carpal bones are separated.

This animal, which was about the size of a Sheep, though of more delicate
proportions, was allied not only to the Tragulidae but to the Giraffidae;
it is impossible to refer it definitely to either family.

B. TYLOPODA.

FAM. 5. CAMELIDAE.--This small group of Selenodonts includes only the
Camels and Lamas. The limbs are long and have no traces of the second and
fifth toes. The fused metacarpals and metatarsals diverge somewhat at their
distal ends. In the upper jaw is a single pair of incisors. The stomach
differs from that of the typical Ruminants. The rumen has smooth and not
papillose walls, and from it are developed the "water cells," diverticula
with narrow mouths provided with a closing sphincter muscle. The psalterium
is reduced to a mere vestige, and so the stomach has, as in the Tragulina,
but three chambers. This, so far ancient, character in the structure of the
Camel tribe is associated with another, also seen in the more primitive
Ungulates, viz. the diffuse character of the placenta. A very singular
peculiarity of this group is the fact that the blood corpuscles instead of
showing the ordinary mammalian round contours are elliptical.

[Illustration]

FIG. 148.--Bactrian Camel. _Camelus bactrianus._ × 1/30.

The genus _Camelus_, confined to the Old World, is made up of two quite
distinct species, the Bactrian Camel, _C. bactrianus_, with two humps, and
the Dromedary, _C. dromedarius_, with only one. The former species is
Asiatic. It is a singular fact that neither of the species is known to
occur in a genuinely wild condition. The so-called "wild" Camels appear to
be invariably feral. The two species will interbreed; and there is at the
Zoological Society's Gardens such a hybrid, which has the general
appearance and shaggy brown hair[193] of the Bactrian animal, but the one
hump of the Dromedary. It may be that the Bactrian Camels of Lob-nor are
really wild; but the desert contains so many remains of cities destroyed by
sand-storms that these reputed wild {286} Camels may be the descendants of
animals belonging to the inhabitants of those cities. A strayed herd of
Camels has established itself in a feral state in Spain. Otherwise the
genus does not occur in Europe. The Camels are also represented in the New
World. The genus _Lama_ (_Auchenia_ of many authors) belongs to this
family. These Camels differ from their allies in the Old World by their
smaller size, by the absence of the characteristic hump, and by the
dropping of one premolar, the dental formula being otherwise similar. A
variety of names, Lama, Alpaca, Huanaco, Vicuña, have been applied to these
animals; but it appears that the names are in excess of the number of the
species. Mr. Thomas, who has lately inquired into the matter, will only
allow two, the Huanaco, _Lama huanacos_, of which there are two domestic
races, the Llama and the Alpaca, and the Vicuña, _Lama vicugna_. They are
both South American in range. Not only is there a herd of escaped Camels in
Spain, but the Spaniards attempted to introduce and acclimatise the useful
Lama. The first Lama ever seen in Europe was brought in the year 1558 to
{287} the town of Middelburg in Holland; it was purchased and presented to
the Emperor of Germany. Gesner gives a curious figure of it, representing
the animal as a comparatively colossal beast submitting itself to the
guidance of a dwarfish man. The habit of "spitting" of the Lama is well
known. Augustin de Zarate and Buffon speak of the Lama as having no
protection save this habit, which is more than a mere ejection of saliva:
the contents of the stomach are forcibly shot at the object of its
annoyance. It can also kick and bite. In the intestines (as in those of
some other mammals) are found Bezoar stones, or Bezards as they are
variously spelt. These were once valued in medicine, and even so lately as
1847 were, according to Gay, the historian of Chili, in vogue; these
concretions, comparable to the ambergris of the Whales, were supposed to be
an antidote to poison.

[Illustration]

FIG. 149.--Lama. _Lama huanacos._ × 1/12.

EXTINCT CAMELS.--The earliest cameloid type is the genus _Protylopus_,[194]
of which we are acquainted with an imperfect skull {288} and the greater
part of a radius and ulna belonging to one individual, and most portions of
the hind-limbs in other specimens. The one species, _P. petersoni_, was
about the size of a "jack rabbit," and is late Eocene (Uinta formation) and
American in range. The teeth of this mammal are the typical forty-four, and
the canines are not pronounced, being incisiform in shape. In the skull the
nasals overhang, as in the genus _Poebrotherium_. The orbit is not closed
by bone. There is in this ancient Camel a trace of the supra-orbital notch
so characteristic of the Camel tribe. "The vertebrae resemble those of the
modern Lamas closely in their general proportions." The lumbars have the
usually Cameloid formula of 7. This genus has but two functional toes on
the hind-feet, the second and fifth being reduced to vestiges. It is
interesting to note that the radius and ulna appear to remain distinct,
except in very old animals, in which they come to be co-ossified in the
middle only, thus foreshadowing their complete union in the next genus,
_Poebrotherium_. The present genus, moreover, as well as _Poebrotherium_,
was distinctly unguligrade; it has not acquired the characteristic
phalangigrade mode of progression of the modern types of Camels.

[Illustration]

FIG. 150.--Skull of _Poebrotherium wilsoni_. _i_^1, _i_^2, _i_^3, Incisors
1-3. × ½. (After Wortman.)

The American and Oligocene _Poebrotherium_ has been recently and
exhaustively studied by Professor Scott.[195] It was considerably smaller
than a Lama. Its neck was long as compared with other Artiodactyles, but
still shorter than that of the Lama. It was a lightly-built, graceful
creature, with apparently some external likeness to a Lama. It is an
important fact to notice that at this {289} period, and for a long time
after, there were no types referable to the Camelidae in the Old World.
Though a Camel in many features of its organisation, _Poebrotherium_ was
"generalised" in many ways. Thus the metacarpals and metatarsals were not
fused to form a cannon bone, and the two lateral digits were represented by
splint rudiments of metacarpals and metatarsals. The dentition was
complete. The skull though distinctly Tylopodan, also shows more
generalised characters. Thus the orbit is not quite, though nearly,
completed by bone. In the Camel it is quite closed. The nasal bones are
much longer, reaching nearly to the end of the snout. The odontoid process
of the axis vertebra is not spout-like as in existing forms, but
cylindrical, though slightly flattened upon the upper surface. The scapula
is described as being more like that of the Lama than of the Camel, though
variations occur which approximate to the Camel. The brain, judging of
course from casts, has those sulci "which are common to the whole series of
Ungulates, and closely resemble those of a foetal Sheep."

[Illustration]

FIG. 151.--Anterior surface of axis of Red Deer, × 2/3. _o_, Odontoid
process; _pz_, posterior zygapophysis; _sn_, foramen for second spinal
nerve. (From Flower's _Osteology_.)

Later in historical sequence than _Poebrotherium_, and structurally
intermediate between it and _Protolabis_, is the Miocene genus
_Gomphotherium_. It shows an advance in structure upon _Poebrotherium_, in
that the orbit is completely encircled by bone, though the posterior wall
is thin; the lower canines instead of being incisiform are curved back as
in later Camels, and separated by a wide diastema from the preceding and
the succeeding teeth.

Later in age than _Poebrotherium_ is _Protolabis_, a _Tylopod_ in which the
full number of teeth is still retained; its skull presents no particular
changes from the Poebrotherine type; the nasals, however, are somewhat
shortened.

Later still in point of time is _Procamelus_. In this form we have
apparently an ancestral stock, whence both Camels and Lamas were derived.
The upper incisors are as in existing forms, but the first and second
persist for a somewhat longer time. The skull shows two well-marked types
of structure; in _P. occidentalis_ {290} there are more points of likeness
to the Lama, in _P. angustidens_ to the Camel. In both, the orbits are
completely encircled by bone. The nasals are much shortened. The odontoid
process of the axis is still more concave than in _Poebrotherium_, but not
spout-like as in existing forms. This fact shows that the spout-like
character of the Camels' odontoid process is not a point of affinity to
other Artiodactyles--in fact the occurrence of the same form of odontoid
process in Perissodactyles is enough proof of this. We must come to the
conclusion that the form is adaptive in all cases. If we were not obliged
on palaeontological evidence to come to this conclusion, the structure in
question is just one which would be fastened upon as evidence of genetic
affinity; for it is a resemblance in a small though distinctive point of
structure having no obvious relation to utility. The metacarpals and
metatarsals have coalesced to form the cannon bones, though a rudiment of
one metacarpal seems to remain. The genera referred to appear to be on the
direct line of descent of the modern representatives of the family. But
there are other forms which are offshoots of the main stem. Such are
_Homocamelus_, _Eschatia_, and _Holomeniscus_. The last two are Pliocene
and American; the teeth are much reduced.

C. PECORA.

The Pecora are a group which possess so many characters in common that it
is not an easy task further to subdivide them.

In all there are but two functional digits on the feet, and the metacarpals
and metatarsals of these are fused. There are no upper incisors, and
canines in the upper jaw are not universal, and generally small. Horns are
confined to this group of the Selenodontia.[196] The premolar teeth are of
a simpler form than the molars. The stomach has four chambers, of which two
may be regarded as belonging to its cardiac half and two to the pyloric.
The former are, in the first place, a large paunch or rumen, followed by a
smaller reticulum, so called on account of the network arrangement of the
folds of its lining membrane. Connected with the latter, and constituting
the first part of the pyloric half of the stomach, is the psalterium or
"manyplies," so called on account of the longitudinal folds, like the
leaves of a {291} book, into which its lining membrane is raised. Finally
there is the abomasum, out of which proceeds the small intestine. Garrod
has observed that the chamber of the stomach which varies most among the
Pecora is the psalterium. This chamber is specially large in _Bos_, and
particularly small in the Antelopes _Nannotragus_ and _Cephalophus_. But
its variation relates more especially to the folds of its mucous membrane.
These folds are of varying lengths and have a definite arrangement There
may be as many as five sets of laminae of regular depths. The most simple
psalterium is that of _Cephalophus_, where there are only two sets of
laminae of different sizes, a deeper set and a very much shallower set;
this form is termed by Garrod "duplicate." Most common is the
"quadruplicate" arrangement, with four sets of laminae of differing depths.
In all Pecora the liver is but little divided by fissures.

FAM. 6. CERVIDAE.--The Deer tribe is a very extensive one, and, with the
exception of Africa and Australia, world-wide in distribution.[197]

The Deer are absolutely distinguished from all other Ruminant animals by
the existence of antlers, which are invariably present in the male sex,
save in the aberrant genera _Moschus_ and _Hydropotes_; in the Reindeer
alone are antlers present in both sexes. The general characters of these
appendages have been dealt with on a former page (p. 200), where they are
compared to, or rather contrasted with, the horns of the Bovidae. These
antlers, so characteristic of the Cervidae, are very variously developed
among the members of the family. Thus in _Elaphodus_ the antlers are very
small and entirely unbranched. In the Muntjacs, _Cervulus_, the antlers are
hardly larger, but they have a small anterior branch arising from near the
pedicel, the "brow tine." In _Cariacus antisiensis_ only one branch, the
brow tine, is present, but it is nearly as long as the main stem of the
antler, the "beam." In _Capreolus capraea_ the beam bears two tines; in
_Cervus sika_ three; in _C. duvauceli_ two of the three tines present bear
secondary branches. There are other complications (some of which are
illustrated in Figs. 152-157) of the simple antler which culminate in the
complex antlers with their expanded "palms" of the Elk and the Fallow Deer.
{292}

Another highly-interesting fact concerning these same antlers is their
gradual increase in complexity of tines and palm from the Miocene _Cervus
matheroni_ to the great Irish Elk of post-Tertiary times.

Beyond the antlers there seems to be no character of universal
applicability which distinguishes the Cervidae from the nearly-related
Antelopes. There are, however, a number of structural features which are
_nearly_ universally characteristic. Excepting _Moschus_ (which Professor
Garrod would not allow to be a "Deer"), no Cervine has a gall-bladder[198]
to its liver. All Bovidae (including Antelopes) have, with the exception of
_Cephalophus_.

A small but constant character of the Deer is the existence of two orifices
to the lachrymal duct. The genus _Tragelaphus_ alone among Antelopes shows
this character.

So far as is known the placenta of the Deer has but few cotyledons, that of
the Bovidae many. But not many types are known.

The navicular, cuboid and ectocuneiform are often united. This is never the
case in the Bovidae.

The first and second phalanges of the lateral (imperfectly developed)
digits are always present except in the Muntjacs; they are never found in
Bovidae. The Deer always present a light brown to a darker brown
coloration. _Elaphodus michianus_ is almost black. There is commonly white
on the under parts and beneath the short tail. Some Deer, such as the
Fallow Deer, are spotted; and the young of others that are uniformly
coloured when adult are spotted. In some cases a winter coat, darker than
the summer coat, is developed.

Altogether some sixty species of Deer are known, of which the preponderance
are Old-World forms. The Deer of the Old World are distributed among the
genera[199] _Cervus_ (all Europe and Asia); _Cervulus_, the Muntjacs
(India, Burmah, China, etc.); _Hydropotes_ (Eastern China); _Capreolus_
(Europe and Central Asia); _Elaphodus_ (Eastern China); there is one
American _Cervus_, the Wapiti. The American genera are _Cariacus_ and
_Pudua_. The Elk (_Alces_) and the Reindeer (_Rangifer_) are circumpolar.
The principal structural modification which occurs within {293} the family
Cervidae concerns the rudimentary fifth and second toes. In _Capreolus_,
_Hydropotes_, _Moschus_, _Alces_, _Rangifer_, and _Pudua_ there are
considerable remains of the lower parts of metacarpals II. and V.; in the
other genera smaller traces of the upper ends of the same bones.

The two most abnormal genera are _Moschus_ and _Hydropotes_, more
particularly the former, which neither Sir V. Brooke nor Professor Garrod
allow to be members of the family at all. _Moschus_ is usually placed in a
special sub-family by itself, Moschinae, the remaining Deer being referred
to another sub-family, Cervinae.

SUB-FAM. 1. CERVINAE.--The genus _Cervus_ comprises rather over twenty
existing species, which, except the Wapiti (_C. canadensis_), are
exclusively Old World in distribution. The principal features of variation
in the genus, in accordance with which it has been divided up into
sub-genera, are (1) palmated (Fallow Deer, _Dama_) or non-palmated antlers;
(2) adults spotted with white at all ages and seasons (_Axis_), or in
summer only (_Pseudaxis_), or not at all; (3) spotted or unspotted young;
(4) existence or absence of rudimentary canines in the upper jaw.

Among the members of this genus, _Cervus (Elaphurus) davidianus_ is
interesting as having been first observed by the missionary Père David in a
park belonging to the Emperor of China near Pekin. Its horns are remarkable
for dividing early into two branches of equal length, of which the anterior
again branches into two. Specimens of this Deer were ultimately obtained
for the Zoological Society's Gardens.

The species of _Cervus_ are fairly distributed between the Palaearctic and
the Indian regions. The Palaearctic species, such as Lühdorff's Deer (Fig.
152), are mainly Asiatic. _Cervus elaphus_ and _Cervus dama_ alone are
European and British. The former of course is the Red Deer, the latter the
Fallow Deer. The Red Deer is reddish-brown in summer and greyish-brown in
winter, with the white patch on the rump so common in the Deer tribe. The
Red Deer is genuinely wild in Scotland, in certain parts of Devonshire and
Westmoreland, and in the New Forest. At the beginning of the last century,
according to Gilbert White, there were 500 head of deer in Wolmer Forest,
which were inspected by Queen Anne. The antlers may have as many as
forty-eight points; and a stag with more than the three anterior tines is
termed a "Royal Hart." The Fallow Deer has {294} palmated antlers, and is
usually spotted. It seems to be an introduced species, common report
pointing to the Romans as the introducers. It would be more correct to say
"re-introduced," for fossil remains of this Deer have been met with.

[Illustration]

FIG. 152.--Lühdorff's Deer. _Cervus luehdorffi._ × 1/15. (From _Nature_.)

_Elaphodus_[200] contains probably two species, _E. cephalophus_ of
Milne-Edwards and _E michianus_ of Swinhoe, both from China. The antlers
are small and unbranched; the canines in the male are massive; it differs
from _Cervulus_, to which it is closely allied, principally in the absence
of frontal glands. The second {295} species has a dark iron-grey pelage,
and the late Mr. Consul Swinhoe described it as very Goat-like in aspect.

_Capreolus._--The Roe Deer has fairly complex antlers. It is a small Deer
and has spotted young. The common Roe Deer, _C. capraea_, is a native of
this country. It is the smallest of our Deer, and its antlers only have
three tines in stags of the third year. It is a singular fact about this
Deer that though the pairing season is in July and August, the young are
not born until the following May or June, a period which does not represent
that of gestation. The germ remains dormant for some time before
developing.

[Illustration]

FIG. 153.--Mule Deer. _Cariacus macrotis._ × 1/15. (From _Nature_.)

The Muntjacs, _Cervulus_, form a distinct generic type confined to the
Indian and the South-Eastern Palaearctic region. They are small Deer with
spotted young, and short one-branched antlers placed upon pedicels as long
as themselves. The canines are strongly developed in the males. There are
about half-a-dozen species.

_Cariacus_ is exclusively American in range, and contains about twenty
species. There are or are not upper canines. The young {296} are spotted.
The antlers are occasionally very simple; in _C. rufus_ and a few allies
(placed in a special sub-genus _Coassus_) they are simple spikes without
branches. In this genus, and in the nearly allied and also New-World
_Pudua_, the vomer is prolonged backwards and divides the posterior nares
into two. The bulk of the species are South American.

[Illustration]

FIG. 154.--Chilian Deer. _Cariacus chilensis._ × 1/12. (From _Nature_.)

_Pudua_, just mentioned, comes from the Chilian Andes. It is a small Deer
without canines and with minute antlers. Other generic names have been
proposed for various species of American deer.

_Hydropotes inermis_ is a small perfectly hornless Deer, living on the
islands of the Yang-tse-kiang. The male has tusks; the young are spotted.
Though, like other deer, _Hydropotes_ has no gall-bladder, both Mr.
Garrod[201] and Mr. Forbes[202] found the {297} rudiments of one in the
shape of a white ligamentous cord. Mr. Forbes has especially dwelt upon the
likeness of the brain to that of _Capreolus_. The female has four teats,
and produces three to six young at a time.

[Illustration]

FIG. 155.--Water Deer. _Hydropotes inermis._ × 1/10. (From _Nature_.)

_Alces machlis_, the Elk or Moose, is a circumpolar species with palmated
antlers and is of large size. The young are unspotted. This animal is the
largest of the Deer tribe. The aspect of this creature is by no means that
of a Deer, the long, thick, and rather prehensile upper lip not by any
means suggesting the family to which it belongs; the legs, too, are
ungainly through their unusual length. The Moose has a curious method of
protecting himself from Wolves. Instead of moving about during heavy
snowstorms, and being thus on the heavy ground an easy prey for these agile
enemies, the animal forms what is known as a "Moose yard." An area of
ground is kept well {298} trampled down, and the animal contents itself
with browsing upon the adjacent stems. The well-trampled ground gives an
easy footing, and by his powerful horns the great stag is able to keep his
enemies at bay.

[Illustration]

FIG. 156.--Moose. _Alces machlis._ × 1/20.

_Rangifer tarandus_, the Reindeer, is unique among Deer by reason of the
fact that both sexes wear antlers. These antlers are palmated. The brow
tine and the next or bez tine are also palmated and are directed forwards
and a little downwards. The young are unspotted. The pelage alters in
winter. Like the Moose, the Reindeer is circumpolar. As is well known,
during the Pleistocene period the Reindeer extended its range as far as the
South of France. Even in the historic period it is said to have been hunted
in Caithness.

Reindeer, like so many other particularly Arctic animals, have regular
migrations. In Spitzbergen, for instance, the animal migrates in the summer
to the inland region of the island, and in {299} the autumn back again to
the sea coast to browse upon the seaweed. These migrating herds have been
stated to be led by a large female.

[Illustration]

FIG. 157.--Reindeer. _Rangifer tarandus._ × 1/15.

SUB-FAM. 2. MOSCHINAE.--_Moschus moschiferus_[203] is a native of the
Asiatic Highlands. It is 3 feet or so high, perfectly hornless, and with
very large canines in the male. It is noteworthy that in _Hydropotes_,
where the canines are also very large, horns are absent. These are
examples, perhaps, of correlation. The musk sac (whence the name) is
present on the abdomen of the male only. There is no crumen or suborbital
gland, which is so generally (though by no means universally) present in
Cervidae. But the male has, in addition to the musk glands, glands near the
tail and on the outside of the thigh. Unlike other Deer, the lachrymal bone
of _Moschus_ bears but one orifice. The feet, so far as concerns the
preservation of the outer rudimentary {300} metacarpals, are of the more
ancient type represented in _Alces_, _Hydropotes_, etc. A gall-bladder is
present. The young, as in so many Cervidae are spotted; but the adult is of
a greyish-brown colour.

[Illustration]

FIG. 158.--Musk Deer. _Moschus moschiferus._ × 1/6. (From _Nature_.)

There is no doubt that _Moschus_ is more nearly related to the Cervidae
than to any other Ruminants. It is regarded by Sir W. Flower as "an
undeveloped deer--an animal which in most points (absence of horns, smooth
brain, retention of gall-bladder, etc.) has ceased to progress with the
rest of the group, while in some few (musk gland, mobile feet) it has taken
a special line of advance of its own."

The musk itself, which gives its name to the creature, is found in a gland
on the belly, about the size of a hen's egg. The whole gland is cut out and
sold in this condition. Such quantities of musk deer have been and are
killed for this purpose that the rarity of the animal is increasing. In the
seventeenth {301} century it was so common that the traveller Tavernier
purchased 7673 musk "pods" in one journey, or, according to Buffon, 1663.
The tusks, which recall those of _Hydropotes_, to which _Moschus_ is not
nearly allied, and of _Tragulus_, with which it has of course still less
connexion, are said to be used for the digging up of roots. Its feet, in
relation to its mountain-ranging habits, are very mobile.

EXTINCT SPECIES OF DEER.--It has been already mentioned that the most
primitive kinds of Deer had no horns at all, resembling in this the modern
_Moschus_ and _Hydropotes_, and that with lapse of time went hand in hand
an increasing complexity of antler; the facts of palaeontology harmonising
in the most striking manner with the facts of individual development from
year to year. The oldest forms seem to be more nearly akin to the living
Muntjacs, and their remains occur in the lowest Miocene beds of both Europe
and America. At present the group is confined to the warmer parts of Asia
and some of the islands belonging to that continent.

One of the oldest types is _Amphitragulus_. This genus, which consists of
several species, inhabited Europe, and differed from living Muntjacs in
being totally hornless in both sexes; the skull had no lachrymal fossa or
deficient lateral ossification.

Nearly allied is _Dremotherium_ of similar age and range.

The Middle Miocene has furnished the remains of the genus _Dicroceras_.
This is the earliest Deer in which horns have been found. The horns are, as
the name of the genus implies, bifid, and have, like those of the living
Muntjac, a very long pedicel. This is also a European genus like the last.
From this period we come across true Deer, which commence in the Upper
Miocene and have branched horns. Moreover they belong, at least for the
most part, to the existing genera. One of the most remarkable forms is
_Cervus sedgwicki_ (sometimes placed in a separate genus, _Polycladus_)
from the Forest Bed of Norfolk and from the Upper Pliocene of the Val
d'Arno. This creature was remarkable for its multitudinously-branched
antlers. These end in no less than twelve points. No Deer exists or has
existed in which the horns are so completely branched. They are like those
of a Red Deer exaggerated.

[Illustration]

FIG. 159.--Giraffe. _Giraffa camelopardalis._ × 1/40.

FAM. 7. GIRAFFIDAE.--Undoubtedly the type of a distinct family, Giraffidae,
is the genus _Giraffa_. It is characterised by {302} the long neck, which,
nevertheless, consists of only the normal seven vertebrae, and by the
"horns" which differ from those of all other Ruminants; they are small bony
prominences of the frontal bones, which become fused with the skull, and
which are covered with unmodified skin. They are not shed. Between them is
a median prominence. This cranial armature is present in the female as well
as in the male, and is well developed even in the {303} new-born young. The
orbits are completely encircled by bone, and there is no lachrymal fossa,
so common in Deer and Antelopes. There are no canines above; but these are
present in the lower jaw. The rudimentary digits of other Ruminants have
disappeared in this genus. There are fourteen pairs of ribs as in many
other Artiodactyla. The liver of the Giraffe[204] is, as in many, but not
all, Ruminants, devoid of a gall-bladder; neither has it a caudate or a
Spigelian lobe. The caecum is actually largish (2½ feet in length), but is
relatively very small, as the small and the large intestines measure 196
and 75 feet in length respectively. The Giraffe has a well-marked
"ileo-caecal" gland, found in many Ruminants; its appearance in _Giraffa_
is especially compared by Garrod with its appearance in _Alces_.

Considered by itself, _Giraffa_ forms a very isolated type of Ruminant. But
after we have dealt with certain facts concerning extinct forms clearly
allied to _Giraffa_, the isolation of the family will be found to be less
marked.

The Giraffe ("one who walks swiftly," the word means in Arabic) is, as
every one knows, limited in its range to the African continent. It is not,
however, so familiar a fact that there are two quite distinct species of
Giraffe, one a northern form from Somaliland, and the other South African.
The distinctness of these two, _G. camelopardalis_ and _G. australis_, has
been lately worked out in some detail by Mr. de Winton.[205] The principal
point of difference between them consists in the large size of the median
horn in the Cape species, which is represented by the merest excrescence in
the other species. The Giraffe of West Africa is held to differ from the
northern and southern species, coming nearer to the former. It appears in
the first place to be a larger animal, and slight differences in the skull
have been pointed out. This series of peculiarities may be expressed, for
those who do not object to trinomial nomenclature, by calling this novel
western form _Giraffa camelopardalis peralta_. The existence of the three
horns covered with unaltered skin is the main characteristic of this
Ungulate. But the Giraffe also differs from other Artiodactyles by its
enormously long neck, which enables it to browse upon trees inaccessible to
the common herd {304} of Ruminants. The neck is often supposed to have some
relation to this method of feeding. But a more ingenious explanation of its
inordinate length is that it serves as a watch-tower. The long grass of the
districts inhabited by the animal swarms with Lions and Leopards, which
must be foes. The long neck allows of a wide look out being kept, and it is
noteworthy that the Ostrich, living under similar conditions, is also
renowned for its length of neck. It is the spots upon the Giraffe which
have given it its name of Cameleopard; these spots present in the southern
form a series of chocolate-coloured areas, sharply marked off by white
spaces. Of these spots it is asserted that they serve as a means of
concealing their possessor. Sir Samuel Baker[206] wrote of it in the
following words: "The red-barked mimosa, which is its favourite food,
seldom grows higher than 14 or 15 feet. Many woods are almost entirely
composed of these trees, upon the flat heads of which the giraffe can feed
when looking downwards. I have frequently been mistaken when remarking some
particular dead tree-stem at a distance that appeared like a decayed relic
of the forest, until upon nearer approach I have been struck by the
peculiar inclination of the trunk; suddenly it has started into movement
and disappeared."

The Giraffe, remarked Pliny, "is as quiet as a sheep." The Roman public, to
whom the first Giraffe ever brought into Europe was exhibited, expected
from its name "to find in it a combination of the size of the camel and the
ferocity of a panther." As a matter of fact, Giraffes in captivity are not
always sheep-like in temper. They will kick with viciousness and vigour,
and will even initiate an attack upon their keeper. At the same time they
are singularly nervous creatures, and have been known to die from a shock.
In moving, the Giraffe uses the fore- and hind-limb of each side
simultaneously; this gives to its gait a peculiar rocking motion, the
singularity of which is heightened by the curving movements of the long
neck, which even describes now and then a figure of eight in the air.
_Giraffa camelopardalis_ and the species (?) already referred to are the
only existing Giraffes (of the genus _Giraffa_), and they are not found out
of Africa. Sir Harry Johnston has lately given a brief account of a larger
and more brilliantly coloured species from Uganda {305} which will probably
prove to belong to a distinct genus. It has five horns, the additional pair
being placed above the ears.

Sir Harry Johnston has quite recently made known another genus of
Giraffidae living in the Semliki forest, Belgian Congo district. The skin
and two skulls, as well as the bones of the feet, are known from specimens
sent by Sir Harry Johnston to the Natural History Museum, and briefly
described to the Zoological Society by Professor Ray Lankester.[207] This
creature, of which the native name is "Okapi," is proposed to be called
_Ocapia johnstoni_. The first actual specimens which reached this country
were two bandoliers made from the skin of the flanks, which were striped
black and white, and were not unnaturally held to be portions of the skin
of a new species of Zebra. The animal is of about the size of a Sable
Antelope, and the back and sides are of a rich brown colour; it is only the
fore- and hind-limbs which are striped, the striping being longitudinal,
_i.e._ parallel with the long axis of the body. The head is Giraffe-like,
but there are no external horns; wisps of curled hairs seem to represent
the vestiges of the horns of other Giraffes. The tail is rather short, and
the neck is rather thick and short. The skull is clearly Giraffine. The
basicranial axis is straight, and the fontanelle in the lachrymal region is
very large. Upon the frontal bones near their parietal border is a large
boss on either side, which presumably represents the horn core or "os
cornu." On the mandible the great length of the diastema between the
incisors and premolars is a Giraffine characteristic. The Okapi lives in
pairs in the deepest recesses of the forest.

We are acquainted with a few extinct forms, belonging to _Giraffa_, which
are extra-African in range. _G. sivalensis_ is from the Pliocene of the
Siwalik Hills in India, _G. attica_ from Greece. These remains, however, do
not include the top of the skull, so that it is doubtful whether their
horns were as in _G. camelopardalis_.

A closely-allied genus is the extinct _Samotherium_. This flourished in
Miocene times, and its remains have been found in the Greek island of
Samos. The neck and limbs are shorter than in the Giraffe, and the horns,
longer than in _Giraffa_, are placed just above the orbit upon the frontal
bones alone, instead of upon the boundary line of frontals and parietals as
in _Giraffa_. In several ways, therefore, the existing Giraffe is a more
modified or {306} specialised animal than its forerunner of the Miocene. In
the latter, the male alone carried horns, and in neither sex does the
unpaired median bony excrescence appear. The remains of this genus
(probably even the same species, _S. boissieri_) also occur in Persia.

_Helladotherium_ (there is but one species, _H. duvernoyi_) has its four
limbs of nearly the same length; the skull of the only known example is
hornless; the neck is shorter than in _Giraffa_. It is known from the
Miocene deposits of Pikermi in Greece.

_Palaeotragus_ is a genus which is not referred to the Giraffidae by all
systematists. Its very name, given to it by the eminent French
palaeontologist M. Gaudry, indicates his opinion as to its Antelopine
affinities. The chief and indeed (according to Forsyth Major[208]) the only
reason for placing this Ruminant with the Antelopes is the large size of
the horns. They undoubtedly suggest the horn cores of Antelopes. But they
are placed wider apart than in those animals. It is thought that the
hornless _Camelopardalis parva_ is the female of this species, which is
from Pikermi.

Rather more different from _Giraffa_ is the extinct genus _Sivatherium_,
from the Siwalik deposits of India. Here again there has been some
discussion as to its affinities. Some place it in the neighbourhood of
_Antilocapra_, but most palaeontologists now regard it as a Giraffe. The
main peculiarity of this large beast was the existence of two pairs of horn
cores; the larger are upon the parietal bones, and are of a palmated form,
with a few short tines, which are highly suggestive of those of the Elk
(_Alces_). The shorter anterior pair are upon the frontal bones. The neck
is short, the limbs of equal length, and there are no additional toes upon
the limbs. _Sivatherium_ was almost as large as an Elephant, and in
restorations it is depicted as having a fleshy dilated nose like the Saiga
Antelope; this view is based upon the position and size of the nasal bones.
Hornless skulls have been identified as the female of _Sivatherium_.

_Vishnutherium_, _Hydraspotherium_, and _Bramatherium_ are allied genera.

FAM. 8. ANTILOCAPRIDAE.--This family contains but one genus and species,
the N. American "Pronghorn," _Antilocapra americana_. This animal deserves
a family to itself on account of the singular structure of the horns, which
are intermediate in character {307} between those of the Deer and those of
the Antelopes. They are unquestionably "hollow-horned" Ruminants, in that
there is an osseous horn core, upon which lies the actual horn. This,
however, is softer than in Bovidae, and is semicorneous. It is, indeed,
more like the velvet of the stag's horn. Moreover the horn is branched, and
there are sometimes even three prongs. Furthermore, it is now certainly
known that the Pronghorn sheds its horns not merely occasionally, but with
definite annual periodicity. It so far resembles the Deer. But it must be
borne in mind that in the Deer the horn shedding is a twofold process.
There is first of all the stripping off of the velvet, and secondly the
shedding of a portion of the horn core down to the burr. What happens in
the Prongbuck is the shedding of the true horn only ( = the shedding of the
velvet), _not_ of the horn core. It appears, however, that occasionally
(once in their lifetime?) certain undoubted Antelopes may cast their
horns.[209] Another external character of this animal is the total absence
of "false hoofs," the last vestiges of the second and fifth digits. The
Pronghorn is a gregarious creature running in bands of six up to hundreds.

FAM. 9. BOVIDAE.--This family, more extensive than that of the Cervidae,
contains not only the Oxen, Sheep, and Goats, but also the Antelopes, save
only _Antilocapra_, which must be placed in a family by itself. The only
two points which distinguish all Bovidae from all Cervidae[210] are the
nature of the horns already described, and the polycotyledonary condition
of the placenta. Moreover the horns are usually present in both sexes,
though there are exceptions, such as the Sheep and Goats, and various
genera of Antelopes (_Tragelaphus_, _Tetraceros_, etc.). There are never
the first two phalanges belonging to the rudimentary digits II., V., as
there are in all Deer excepting _Cervulus_. There is as a rule but one
orifice to the lachrymal duct. There are never persistent upper canine
teeth in either sex.

It is exceedingly difficult to separate the Antelopes from the Sheep, Oxen,
and Goats. Their inclusion along with these creatures in one family,
Bovidae, shows that no differences of an important character exist. The
term Antelope is rather of popular than {308} of zoological significance.
As a rule there are horns in both sexes; but this rule is not without
exceptions, of which one is the genus _Strepsiceros_, the Koodoo. Many
other Bovidae are horned in the males only, e.g. _Saiga_, _Tragelaphus_.
The Antelopes further differ from the true Oxen in their more graceful
build, and in the fact that the horns, if they curve at all, generally
curve backwards towards the neck. In the Oxen, on the other hand, the build
is stouter, and the horns usually curve outwards. The same remarks apply to
the Sheep. Such an Antelope, however, as the Eland (_Orias_) is very
Ox-like in habit. Another feature which may be remarked upon, though not of
absolute differential value, is that while the Antelopes are as a rule
smooth and sleek in their skins, the Oxen tend to be rough and shaggy. The
Zebu, however, in this, in its hump, and in general aspect, is far from
being unlike an Eland. But then the Zebu is a domestic race, and we do not
know what the wild stock was like. It is perhaps with the Goats that the
Antelopes have the nearest affinities, and it is difficult to place such a
form as _Nemorrhaedus_, and indeed some others. In the Antelopes as a rule
the middle lower incisors are larger than the lateral ones; in the Sheep
and Goats they are alike in size. The parietal bones, too, in the Antelopes
are moderately large and are much shortened in the remaining Cavicornia,
especially in the Oxen. As the Antelopes are the oldest, so far as we know,
of all bovine animals, one would expect to find them combining the
characters of the rest. But they do this so effectually that a
disentanglement is really impossible. They date from the Miocene. Antelopes
are now limited to Europe, Asia, and Africa; they have always had the same
range, though more abundant in former times in Europe. They preponderate
now in tropical Africa, and abound in genera and species. Messrs. Sclater
and Thomas[211] allow altogether thirty-five genera, of which twenty-four
are exclusively Ethiopian in range.

In the following summary of the group Messrs. Sclater and Thomas's work is
followed. They commence with a section or sub-family of which the type is
the Hartebeest.

_Bubalis_, or _Alcelaphus_ as it is sometimes called, is an African genus,
ranging however into Arabia. These Antelopes are characterised by the long
skull and the doubly-curved horns. There are eight species of the genus, of
which _B. caama_ is the {309} best known; this is the animal known as the
Hartebeest. The Bontebok and Blessbok belong to a closely-allied genus,
_Damaliscus_, distinguished mainly by the fact that the bony base of the
horn cores is not extended upwards, and therefore the parietal bones are
visible when the skull is viewed from in front, which is not the case in
_Bubalis_.

[Illustration]

FIG. 160.--Brindled Gnu. _Connochaetes taurinus._ × 1/20.

The Gnus, _Connochaetes_, are familiar owing to their curious aspect. The
hairy face, and rump and tail like those of a pony are highly
characteristic. The horns are bovine in appearance, standing outwards and
then curving upwards.[212] There are three species of Gnu, all from South
Africa. They are _C. gnu_, _C. taurinus_, and _C. albogulatus_.

Of the Cephalophine section there are two genera:--

_Cephalophus_ is an African genus. These animals are known as Duikerboks;
they are small, and have short non-curved horns in the male sex only. Their
general aspect is not unlike that of certain Deer with simple horns, such
as _Cervulus_. Messrs. Sclater and Thomas allow thirty-eight species. The
{310} smallest species do not exceed the dimensions of a Hare. None are
really large.

_Tetraceros_ is an Indian genus characterised, as its name denotes, by the
fact that it possesses four horns. It is the posterior pair which
correspond to the single pair of _Cephalophus_. The anterior pair, which
are much smaller and are sometimes absent, are a new pair. The female of
this Antelope is hornless. Sheep are occasionally four-horned, and there is
indeed a breed of such in Kashmir. A four-horned Chamois was described by
the late Mr. Alston.

The Klipspringer, _Oreotragus saltator_, is the first type of a third
section; as its name denotes, it is an Antelope with Goat-like habits,
being found particularly among rocks. The horns are short and straight.
This, the only species of the genus, is African in range, of which its
Dutch name gives evidence. A specimen in the Zoological Society's Gardens
(as has been pointed out to me by Mr. Mercer) had the habit of depositing
the secretion of the tear gland upon a mass of concrete in its enclosure,
the secretion thus exuded forming a pointed heap of hardish matter. It may
be that the object of this is to guide its fellows to its whereabouts.

_Ourebia_ is a less-known genus, larger in size, but with horns of the same
character, though longer.

The Grysbok and the Steinbok, genus _Raphiceros_, have similar horns. This
as well as the last two genera have horns in the male only.

One of the smallest of Antelopes belongs to an allied genus; this is
_Neotragus pygmaeus_. It is known as the Royal Antelope, a name apparently
derived from Bosman's statement that the negroes called it "the king of the
harts." Its horns are very small. The height of the animal is only 10
inches. Horns are present in the male alone. The last three genera are
African.

The Cervicaprine series, which is also African, includes the Waterbucks and
Reedbucks, so called on account of their water-loving propensities. As in
the last series, from which they are separated by Sclater and Thomas, but
with which they are united by Flower, there are horns in the male only.
These horns, though not twisted, are long. The typical genus is _Cobus_, of
which there are eleven species. The Waterbuck, _C. ellipsiprymnus_, and the
Sing-sing, _C. unctuosus_, are perhaps the best-known species; the former
is {311} blackish grey, the latter browner in colour. In _C. maria_ and one
or two other species the horns are more curved backwards and again forwards
than in some of the others, where their form is sublyrate.

The Reedbucks, _Cervicapra_, are closely allied to _Cobus_; they are,
however, of smaller size. Here, as in that genus, the females are hornless,
and the horns of the males are of medium size. Five species are referred to
the genus. They are all of a brownish fawn colour. A genus _Pelea_, with
but one species, _P. capreolus_, has been separated on account of the fact
that the horns are nearly straight and that there is no naked patch of skin
beneath the ears. This animal has received its name on account of its
resemblance to the Roebuck.

The Antilopine section includes a number of genera.

The genus _Antilope_ is Indian in range. It includes but one species, _A.
cervicapra_. This Antelope is of medium size, with a brown pelage getting
blacker with years; it is thus known as the Black-buck. The female, which
is hornless, is lighter brown. The horns are long, spirally twisted, and
closely ringed.

_Aepyceros_, with two species, is African. The Palla (_Ae. melampus_) is a
large Antelope, with longish lyrate horns in the male, which are
half-ringed.

The Saiga Antelope, genus _Saiga_, is one of the most remarkable types of
Antelope in its outward appearance. Its nose is very large and inflated,
the two nostrils being quite widely separated, a depression indeed lying
between them dorsally. The horns are lyrate in the male, absent in the
female. The "ovine expression" of this bovine animal is more pronounced in
the female. Corresponding with the clumsy nose are very short nostrils, the
commencement of the narial aperture being therefore very far back. It is
almost suggestive of _Macrauchenia_ in this respect. The fleece is also
Sheep-like. The genus occurred in this country during the Pleistocene. It
is now an inhabitant of Eastern Europe and Western Asia. The only species
is _S. tartarica_.

The Chiru, _Pantholops_, is allied to the Saiga. The horns of the male are
long and nearly straight; they are ringed in front. The muzzle is swollen
in the male; the nostrils are large, and provided with extensive sacs
internally. The colour of this animal, which is exclusively Thibetan in
range, is a pale fawn. The hair, in accord with its habitat, is very
woolly. No living specimens have ever been brought to Europe. This creature
has accumulated much {312} legend. Its blood is believed by the Mongols to
possess virtues, and by means of the rings on the horns fortunes are told.
Naturally the animal is on these grounds hard to stalk and shoot.

[Illustration]

FIG. 161.--Loder's Gazelle. _Gazella loderi._ × 1/10.

The Gazelles, genus _Gazella_, are fairly numerous in species, which are
both Palaearctic and Ethiopian. There are altogether twenty-five of them.
The genus as a whole is characterised by the small or moderate size, the
sandy coloration with white belly, the presence of dark and light stripes
on the face and on the flanks. These streaks, however, are not always
present, and their presence or absence serves to differentiate some of the
species. The horns are usually present in both sexes. The horns are of fair
length, ringed, and of lyrate form.

The Springbok is separated from the rest of the Gazelles, to which genus it
is clearly most nearly related, as a genus _Antidorcas_. This genus differs
from _Gazella_ by having only two lower premolars as in _Saiga_. Otherwise
it resembles the Gazelles; there is but a single species, _A. euchore_,
which is African. {313}

_Ammodorcas_ is closely allied to the Gazelles, but differs from them in
having an elongated neck and also a long tail. _A. clarkei_, the only
species, is limited to Somaliland.

_Lithocranius_, not unlike the last, has a still longer neck, which makes
it almost Giraffe-like; its tail, however, is short. The scientific name is
derived from the "solid stony character of the cranium." In running, this
Gazelle carries the head forward in a straight line with the body. It is
African.

_Dorcotragus_ with one species, _D. megalotis_, is a pigmy Gazelle
restricted to Somaliland. Its likeness, on account of size and in some
other superficial features, to the Klipspringer, led to its original
confusion with that genus (_Oreotragus_).

[Illustration]

FIG. 162.--Sable Antelope. _Hippotragus niger._ × 1/20. The horns of the
specimen figured have not nearly reached their full dimensions.

A sub-family Hippotraginae, or Hippotragine section, includes a number of
Antelopes which agree in the possession of four mammae, and of molars more
like those of the true Oxen, of {314} horns of some length, present in both
sexes, and of a longish tail. They are all African in range.

The type genus _Hippotragus_ has its horns placed above the orbits; they
are not twisted, but curved backwards. There are three species in the
genus. Of these the best known is _H. niger_, the beautiful Sable Antelope.
Its general colour is a rich, dark, glossy brown with white stripes on the
face, and with a white belly. The other species are the Roan Antelope, _H.
equinus_, and the Blaaubok, _H. leucophaeus_, of which the last specimen
was probably killed in 1799.[213]

[Illustration]

FIG. 163.--Beatrix Antelope. _Oryx beatrix._ × 1/16. (From _Nature_.)

The genus _Oryx_ (chiefly African, but also Arabian and Syrian) also
contains a number of species, which are fairly familiar through the fact
that several of them are always on view in the Zoological Society's
Gardens. The genus differs from _Hippotragus_ in that the horns, present in
both sexes, are placed behind the orbits, and slant backwards in a line
with the face. They are annulated. The Leucoryx (_O. leucoryx_) is of a
pale colour, but {315} this is not so marked as in _O. beatrix_, which is
largely white with, however, brown legs. The Gemsbok is a handsome creature
with greyish tawny colour, much darker on the legs, and with a
Gazelle-like, dark, side stripe. It has received its vernacular name on
account of its supposed likeness to the Chamois ("Gemse"), just as the
Rehbok was so-called from its supposed likeness to the Roe Deer, and the
Eland to the Elk. The Beisa (_O. beisa_) is of a similar tawny colour to
the last, and also with darker stripes.

The Addax (_Addax_) of North Africa, Arabia and Syria, has but one species
(_A. nasomaculatus_). The horns are spirally twisted.

[Illustration]

FIG. 164.--Speke's Antelope. _Tragelaphus spekii_ ([female]). × 1/16.

The Tragelaphine section includes the Kudus, Elands, Nilgais, and Harnessed
Antelopes. They are all long-horned (when the horns are present in both
sexes), the horns being twisted; the nose is naked with a slight median
groove, and all are Ethiopian or Oriental in range.

The genus _Tragelaphus_ includes the Harnessed Antelopes, so called on
account of the direction of the stripes suggesting harness. The females are
hornless, and the colours of the two sexes are different. The hoofs are
long and the toes rather unusually separable, which state of affairs is in
accord with the {316} swampy country affected by many. _T. gratus_ and _T.
spekei_ are larger forms; the Boschbok, _T. sylvaticus_, is smaller.

The Kudus, genus _Strepsiceros_, have more markedly twisted horns, which
are absent in the female. The body is vertically striped with white. The
largest species is _S. kudu_; a smaller form, _S. imberbis_, is from
Somaliland.

[Illustration]

FIG. 165.--Eland. _Orias canna._ × 1/25.

The last genus of this section or sub-family is the African Eland, genus
_Oreas_[214] (which it appears should be spelt _Orias_). The Elands are
perhaps more Ox-like in appearance than the other members of this group,
and in both sexes have horns, in which the spiral twisting is more close.
_Orias canna_ is the name of the common Eland. _O. livingstonii_ has been
applied to an East African variety, which has thin and faint lateral
stripes like the other members of the group to which it belongs.

The genus _Boselaphus_ includes only _B. tragocamelus_, the Nilgai, which
is purely Indian in range. The female is hornless, and the horns of the
male are smooth and not long. {317}

The members of the Bovine section or Oxen are to be distinguished from
other hollow-horned Ruminants by their stouter build and by the fact that
the horns stand out from the sides of the skull and are simply curved, not
twisted; and smooth, not annulate like those of other Ruminants. The muffle
is naked, broad, and moist. The Oxen are widely distributed; but are
entirely absent from the Australian region and from South America and
Madagascar.

The true Oxen are perhaps best considered to form but a single genus,
_Bos_. They have, however, been divided into a number of genera. Even the
supposed aberrant _Anoa depressicornis_ of Celebes hardly differs
sufficiently to warrant its separation. In favour of this view, too, is the
extraordinary ease with which different "genera" will cross with each other
and produce fertile offspring. The following is the pedigree of an animal
lately living in the Zoological Society's Gardens. The female offspring of
a male Zebu and a female Gayal was mated with a male Bison. The female calf
was again mated with a Bison and produced a calf, also a female, which
contained therefore the three species, _Bos indicus_, _Bibos frontalis_,
and _Bison americanus_. It is clearly unwise in view of this fact to insist
too much upon generic distinctions in any of those types.[215]

Of this genus the Oriental Gaur (_Bos gaurus_), the Gayal (_B. frontalis_),
and the Banteng (_B. sondaicus_) form a well-marked section, characterised
by their dark coloration and by the somewhat flattened horns.

The Gaur, _Bos gaurus_, has a more concave forehead than its allies; the
horns are less curved than those of the Banteng, and less so than the horns
of the Gayal (_Bos frontalis_). It inhabits the Indian Peninsula; and
extends through Burmah to the extremity of the Malay Peninsula. The Malay
name of this animal is Sakiutan, which simply means wild cattle. It chiefly
frequents wooded hills and is an excellent mountain climber.

_Bos frontalis_, the Indian Gayal, has a white caudal disc like the last
species, but the forehead is flat and the horns curve but little. It is
chiefly known as a tame animal, and its occurrence in the wild state has
been doubted. It has furthermore been suggested that it is merely a tame
race of the Gaur altered {318} slightly through domestication. It is,
however, said not to cross in a state of nature with the Gaur.[216]

[Illustration]

FIG. 166.--Gayal. _Bos frontalis._ × 1/20.

The Banteng, _B. sondaicus_, is distributed through Chittagong, Tenasserim,
and the Malay Peninsula to Java and Borneo. There are apparently two races
of this animal. The species differs from the others by the fact that the
horns are smaller and more curved; there is a white caudal disc; the
forehead is narrower and the skull longer than in the others.

The American Bison and the European Aurochs form another section; they are
indeed extremely alike, specific differences being hardly recognisable. The
Bison of America, formerly present in such numbers that the prairies were
black with countless herds, has now diminished to about a thousand head.

One of the largest of existing Bovidae is the Aurochs, Wisent, or European
Bison, _Bos bonasus_ (or _Bison europaeus_). It is exceedingly like its
American relative. Formerly the animal was much more widely spread than it
is now, extending its range from Europe into North America. It is now
limited to certain districts on the Urals, in the Caucasus, and a herd of
them are kept up through the fostering care of the Emperor of Russia in the
forest of Bielovege in Lithuania. The term "Aurochs" should not really be
applied to this species but to the Wild Cattle, _Bos taurus_. It is,
however, so generally used for the Wisent (which is the German name) that
it {319} is not necessary to change it. The Sclavonic name is Zubr or
Suber. It is a great beast, standing 6 feet or so in height at the
shoulder. It ranged further over Europe well within the historic period. In
the days of Charlemagne it was spread over Germany and was a beast of the
chase. In the year 1848 the Emperor of Russia presented a pair of these
Oxen to the Zoological Society of London. At the time of their presentation
an interesting communication was made to the Society by M. Dolmatoff, on
the method of the capture of these two examples. The creature is not easy
to capture and is alarming to confront. "The eyes," says an old writer,
"are red and fiery; the looks are furious and commanding." It has of course
the shaggy mane and hump of the American animal. The herd in Lithuania was
said to be 1900 in the year 1856. Mr. E. N. Buxton,[217] who has lately
visited the forest, quotes M. Neverli to the effect that at present the
numbers are not more than 700.

[Illustration]

FIG. 167.--Bison. _Bison americanus._ × 1/25.

Allied to this animal, and apparently still nearer to the American Bison,
is the extinct _B. priscus_ of Europe. The Pleistocene Bisons of North
America, _B. antiquus_ and _B. latifrons_, are not remote from the living
forms. Finally, the Miocene _B. sivalensis_ from India, and the Pliocene
_B. ferox_ and _B. alleni_ of North America, take back this group to as
remote a period as any other genus of Oxen. {320}

[Illustration]

FIG. 168.--Yak. _Bos grunniens._ × 1/15.

[Illustration]

FIG. 169.--British Wild Ox. _Bos taurus._ From Vaynol Park, Bangor. × 1/20.

The Yak, _Bos grunniens_, is a long-haired peculiar type, confined to the
Thibetan plateau. _B._ (_Anoa_) _depressicornis_ of Celebes is
characterised by its straight horns; allied to it is _B. mindorensis_
(Philippine Islands), supposed, however, to be a hybrid between {321} it
and some other species. Africa has at least two Buffaloes. We may finally
mention the Wild Ox of Europe, _B. primigenius_, the supposed progenitor of
our domestic cattle, believed to be still surviving in the herds at
Chillingham, Chartley, and elsewhere. This animal is sometimes called the
Aurochs. The Romans spoke of it as the Urus, and it appears to have
formerly attained to more gigantic proportions than at present. It is the
small size of the present race that is the chief objection to tracing them
back to the large Oxen existing near London in 1174, and found sub-fossil
in the Cambridgeshire fens.

[Illustration]

FIG. 170.--Punjab Wild Sheep. _Ovis vignei._ × 1/10.

Of the true sheep, genus _Ovis_, there are a considerable number of
species. The Sheep are to be distinguished from the Goats by their rather
stouter build and by the absence of the beard in the male. The horns are
developed in both sexes, and are usually twisted and often of large size.

The Sheep are almost entirely Palaearctic and Nearctic. They only just get
into the Oriental region. One of the finest species is the great Pamir
Sheep, _O. poli_, whose length reaches 6 feet {322} 7 inches, and height 3
feet 10 inches. The horns of this fine Sheep may measure more than five
feet round the curves. The Rocky Mountain Bighorn (_O. montana_) is a Sheep
ranging along the Rockies as far south as New Mexico, and also to the far
north; they are not confined to the chain of mountains mentioned, but occur
also on the mountains of British Columbia down to those of California. The
horns are not quite as large as those of the last species, but measurements
give a length (along the curve) of 32 to 40 inches.

[Illustration]

FIG. 171.--Himalayan Burrhel Sheep. _Ovis burrhel._ × 1/12. (From
_Nature_.)

[Illustration]

FIG. 172.--Blanford's Sheep. _Ovis blanfordi._ × 1/10. (From _Nature_.)

Just as the Goats are often limited to islands and small stretches of
country, so are the Sheep. Thus Cyprus has a species, _O. ophion_, peculiar
to itself. This, which is known as the Cyprus Mouflon, is limited to a
range of mountains, the Troodos, in that island. In 1878 it was believed
that the animal was nearly exterminated, a flock of twenty-five members
alone surviving. They have, however, since increased. Confined {324} to the
Thibetan plateau are _O. hodgsoni_ and _O. nahura_. Corsica has the
Mouflon, _O. musimon_; and the Barbary Sheep or Arui, _O. tragelaphus_, is
found only in Northern Africa. _Ovis burrhel_ and _O. blanfordi_ are Indian
forms.

[Illustration]

FIG. 173.--Barbary Sheep. _Ovis tragelaphus._ × 1/10.

[Illustration]

FIG. 174.--Thar. _Capra jemlaica._ × 1/10. (From _Nature_.)

_Ovis nahura_ is chiefly responsible for the impossibility of strictly
separating the Sheep and Goats. It has no suborbital glands or lachrymal
fossae, which are as a rule present in the Sheep and absent from the Goats.
On the other hand interdigital glands are present, which is the case with
Sheep. Its habits, too, are a blending of those of the Sheep and the Goat.
It lives largely on undulating ground like Sheep, and frequently lies down
during the day on its feeding ground. On the other hand it is, like the
Goats, a splendid climber.

The Goats, genus _Capra_, differ from the Sheep in their slighter build and
in the fact that the horns are not spirally curved, but arched over the
back. There is also the characteristic beard, {325} and the male is
odorous. The true Goats are almost exclusively Palaearctic in range. They
show the limited distribution of the Sheep, a distribution which follows
from their mountain-loving habits.

[Illustration]

FIG. 175.--Sinaitic Ibex. _Capra sinaitica._ × 1/10.

Thus we have the Spanish Ibex (_C. pyrenaica_), limited to the Pyrenees and
other mountain ranges of the peninsula; _C. ibex_, the Steinbok of the Alps
and the Tyrol; the Markhoor, _C. falconeri_, of certain mountain ranges of
Afghanistan; the Caucasian, Sinaitic, and Cretan Ibexes, and the Thar.

_Capra aegagrus_, the Persian Wild Goat, ranges from the Caucasus to Sind.
It is this animal which produces the true "bezoar stone." The substance in
question is a secretion apparently found in the stomach. It is still,
according to Mr. Blanford, regarded as an antidote to poison in Persia.
Buffon called this Goat the "Pasan," which is evidently a corruption of the
word bezoar. When the substance was in repute as a medicine of the
"alexipharmic" kind, the supply naturally came up to the demand. Thus the
bezoar stones of the Lama in South America gained repute, and there were
"Oriental bezoar, cow {326} bezoar, hog bezoar, and monkey bezoar"! As
concretions of one kind or another are not uncommon objects in the
alimentary tract of mammals it was easy enough to obtain a fair amount of
some substance which was sure to sell well. It is said that a stone
weighing four ounces was once sold in this country (or at any rate in
Europe) for £200.

"There can be no doubt," observes Mr. Blanford, "that _C. aegagrus_ is one
of the species, and probably the principal, from which tame goats are
derived."

[Illustration]

FIG. 176.--Japanese Goat Antelope. _Nemorrhaedus crispus._ × 1/12. (From
_Nature_.)

The Chamois (_Rupricapra_) and the Goral (_Nemorrhaedus_) are best
described as Goat-like Antelopes; but, as already said, it is difficult to
split up the Bovidae satisfactorily. The Rocky Mountain Goat, _Haploceros
montanus_, is a large Goat-like creature, {327} which has the peculiarity
of having the shortest cannon bones of any Ruminant. Its name denotes its
range.

[Illustration]

FIG. 177.--Goral. _Nemorrhaedus goral._ × 1/12. (From _Nature_.)

The Musk Ox, _Ovibos moschatus_, has been thought to be on the borderland
between the Sheep and Oxen, as indeed expressed in its scientific name. It
is a purely Arctic creature, now confined to the Nearctic region; but it
formerly existed in the Arctic regions of Europe.

The anatomy of the "soft parts" of this genus has lately been investigated
by Dr. Lönnberg.[218] The animal has no foot glands such as occur in
_Ovis_. Its kidneys, however, are non-lobate, and it has orbital glands.
The cotyledons of the placenta are unusually large, and the cow has the
"primary four" teats. It cannot, in fact, be definitely referred to either
the Caprine or the Bovine section of the Cavicornia, and while possibly
most allied to _Budorcas_, it may be regarded, at least for the present, as
entitled to form a separate sub-family of its own. The muzzle {328} has a
slight naked strip above the nostrils, as in the Sheep, but there is no
fissure of the upper lip.

EXTINCT FAMILIES OF ARTIODACTYLA.

The origin of the Artiodactyla is placed by Cope in the family
PANTOLESTIDAE,[219] allied to the genus _Protogonodon_ of the Condylarthra.
As, however, this family is represented by but a few back teeth and a
fragment of the hind-foot, it seems premature to regard it as the necessary
starting-point of the Bunodont and Ruminant groups.

FAM. ANTHRACOTHERIIDAE.--This well-known and ancient family consists of
creatures of for the most part a Pig-like form, with teeth approaching the
selenodont shape, and a complete dentition. The carpals, tarsals,
metacarpals, and metatarsals are all free. The toes are four (or five) to
each foot, with the outermost beginning to be reduced. These of course are
all generalised and primitive characters, pointing nowhere in particular,
except, of course, to an Artiodactyle stock, on account of the teeth and
the two predominating toes.

The type genus of the family, _Anthracotherium_, is not, as its name might
seem to denote, a relic of the Carboniferous period; its remains were found
in lignite, which may also show that it was at least semi-aquatic in habit.
Its form, however, must have been Pig-like, so at least one would presume
from the elongated skull and shortish legs. There were species as great as
a Rhinoceros, and smaller forms. The genus began in the Oligocene and
continued down to the Pliocene. It is known from Europe, Asia, and America.

The skull is long with a prominent sagittal crest. The facial part is also
very long, and the orbits are not closed by a bony ring. The premolars are
simple teeth; the molars distinctly bunodont with a tendency in one or two
to the selenodont condition. The canines are powerful, as are also the
incisors. The scapula has been specially compared with that of the Camel.
It has no acromion, which is usually though not always absent in Ungulates.
An ally of the present animal, for instance, the Hippopotamus, has the
acromion developed. The radius and ulna, the tibia and fibula, are all
fully developed. {329}

_Ancodus_ (or _Hyopotamus_, as it has been called) is also Oligocene in
range, and its remains have been found in the same countries as have those
of _Anthracotherium_. Both genera are indeed closely allied. _Ancodus_
seems to be a more slightly-built creature. The skull looks weaker, but
presents much the same features of organisation. In _A. velaunus_, a
species found in French rocks, a metacarpal of digit I. was present in the
manus, while _A. brachyrhynchus_ had a completely five-fingered manus.

The Miocene genus _Merycopotamus_ (from the lower layers of the Siwalik
formation in India) is more distinctly selenodont than the forms already
discussed. On this ground it has been placed in a separate sub-family. As,
however, in other respects it does not depart from the Anthracotherian type
of structure, this proceeding seems to be hardly necessary. There are two
species known, of which one, _M. nanus_, is, as its name denotes, a dwarf
form.

FAM. CAENOTHERIIDAE.--While the last family consisted of animals rather
more akin to the Pigs, the present is more Pecorine in its characters. The
molars are selenodont; but as in the Tragulidae the premolars are more of
the nature of cutting teeth. The dentition, like that of so many of these
early Ungulates, is complete, and the canines are not prominent. The feet
are four-toed, the lateral toes not reaching the ground.

The principal genus is the Eocene and Miocene _Caenotherium_. Of this genus
there were a considerable number of species all European in range, and of
small size--not more than a foot or so in length. Their small size is
suggestive of the Chevrotains. In the skull the orbital cavity is nearly or
quite surrounded by bone, and the tympanic bulla is large and inflated. A
common feature of Artiodactyles, a failure of the nasals and maxillae to
meet at the side of the face, is to be seen in this ancient forerunner of
the Pecora.

_Plesiomeryx_, also European, and from the same geological horizon, is a
very closely allied form.

FAM. XIPHODONTIDAE.--This family consists of slender, small Artiodactyles
which are, like the Caenotheriidae, related to the Pecora. They are
confined in their range to Europe.

The type genus _Xiphodon_ has selenodont molars and elongated, slender,
cutting premolars. The dentition was complete and the canines not highly
developed. Like _Caenotherium_, {330} _Xiphodon_ was a hornless creature,
but with only two toes, the two lateral digits being represented by the
merest rudiments of metacarpals. The other metacarpals were unusually long.

_Amphimeryx_ (also called _Xiphodontotherium_) is much more imperfectly
known, but belongs to this family or to that of the Caenotheriidae.
_Dichodon_ is another member of the same family.

FAM. OREODONTIDAE.--This family, consisting of numerous genera, is limited
to the North American continent. Its range in time is from the Eocene to
the Lower Pliocene. The family as a whole is to be distinguished by a
number of primitive characters. The dentition is complete; the feet are
four- or even five-toed; the orbit is sometimes open behind. The canines of
the lower jaw are not more pronounced than the incisors. The
characteristics of the group will be further developed by a consideration
of some of the principal genera which are included in this family.

_Oreodon_ is a Miocene form about as large as a Peccary. The skull has a
short face with a completely-closed orbital cavity. In front of the orbit
is a deep pit, not a mere deficiency of ossification, such as occurs in
many Artiodactyles. This is placed on the lachrymal bone, and is in fact a
lachrymal fossa, such as occurs in other forms. The odontoid process of the
axis vertebra is somewhat cheese-taster shaped, as in recent Artiodactyles.
There are fourteen dorsal vertebrae and a very large number of caudals. The
radius and the ulna are completely separated, as are the carpals. There are
five digits to the fore-limbs. The fibula is complete and independent. The
hind-foot is four-toed. Several species of the genus are known.

_Merycochoerus_ is an allied Miocene genus. It is more massive in form than
the last, but otherwise does not present differences of importance.

_Mesoreodon_ is another genus of this family which presents some curious
features of organisation. In the skull and teeth there is nothing very
noteworthy, but the hyoid is remarkable. This appendage of the skull is by
no means always preserved, and when it is, it might be denied that it
belonged to any particular skull. In the present case there appears to be
no doubt as to the identity of the bones, which resemble the corresponding
bones of the Perissodactyla much more than they do those of other
Artiodactyles. Associated with the bones an ossified {331} thyroid
cartilage of the larynx was found. As the skull was that of a male, this
character may be a sexual one. It is quite comparable to the ossification
of the same cartilage in the American monkey _Callithrix_. "The function of
the bone," observes Professor Scott,[220] "was probably similar to that
performed by the enormously-inflated basihyal of the howling monkeys, and
must have given to these animals most unusual powers of voice." Another
important anatomical fact about _Mesoreodon_ is the apparent existence of a
clavicle. It is of course conceivable that the remains of some other animal
have got mixed up with that of the individuals upon which the present genus
is founded; but failing that, here is a clavicle in an Ungulate. The spine
of the scapula possesses a metacromion. This greater development of the
spine of the scapula in Artiodactyles than in Perissodactyles is, it is
suggested, to be correlated with the earlier loss of the clavicle in the
latter group of Ungulates.

_Cyclopidius_ (synonymous with _Brachymeryx_) is a kind of pug form of
_Oreodon_. The skull is short and broad, and the end of the snout a little
turned up. The upper incisors are small and drop out early. On each side of
the nasals is a large oval vacuity which is perhaps to be compared to the
lateral deficiency to be found in other Artiodactyles. One species of this
singular-looking form is appropriately called _C. simus_.

Other allied genera are _Merychyus_ and _Leptauchenia_. The former extends
as far down as the Lower Pliocene, and is thus one of the newest forms of
Oreodontidae.

_Agriochoerus_[221] (Fig. 178) is placed in a separate sub-family from the
types which have just been considered. It is Miocene in range. It differs
from _Oreodon_ and its closer relatives by the fact that the orbit is open
behind and not closed. The most remarkable fact about this creature is that
the terminal phalanges of the digits (five in the fore- and four in the
hind-feet) being pointed, seem to suggest their encasement with claws
rather than hoofs. The pollex, though small, seems to have been opposable.
As with other Oreodonts, the molars are selenodont. The premaxillae are
toothless--at least in adults, for two teeth are present in the {332}
young. There are several species. _Agriochoerus_, like _Oreodon_ and
primitive Ungulates in general, had a long tail. The genus thus shows a
mixture of ancient and specialised characters.

[Illustration]

FIG. 178.--Skeleton of _Agriochoerus latifrons_. × 1/8. (After Wortman.)

The most ancient form of Oreodont is _Protoreodon_. This is Eocene, and
became extinct during that period. It had a complete dentition, open orbit,
and no lachrymal fossa. The fore-feet were five-toed, the hind four-toed.

FAM. ANOPLOTHERIIDAE.--This family is entirely Eocene in point of time, and
is unknown outside Europe. The dentition of the group is complete; the
molars are seleno-bunodont, like those of the Anthracotheriidae. The bones
of the carpus, tarsus, metacarpus and metatarsus are all free; the toes are
four to two in number on each foot. The orbit is widely open behind. The
tail is long, as in _Xiphodon_, etc. {333}

These general characters only just serve to differentiate the family; but
they illustrate its archaic character, in which it resembles the
Xiphodontidae, and even more the Anthracotheriidae. A survey of some of the
genera which have been assigned to the family will bring out other features
in the organisation of these very ancient Artiodactyles.

_Anoplotherium_ is so called on account of the fact that it is, like all
ancient Artiodactyles, without horns or claws. Tusks it might have, but as
a matter of fact has not. There are, as in Artiodactyles generally,
nineteen dorso-lumbar vertebrae; the long tail has numerous chevrons. The
shoulder blade has a well-marked acromion and a distinct coracoid process;
it is wide proximally. The bones of the fore-arm and fore-leg are, as is
usual in primitive Artiodactyles, separate.

In the skull the chief features, in addition to that mentioned in the
definition of the family, are the large size of the paroccipital processes;
there is no fossa lachrymalis or deficiency in the side of the face. The
animal is three-toed, both in the fore- and hind-limbs. The second toe is
nearly as large as the Artiodactyle third and fourth. There are tiny
rudiments of the two remaining fingers. The hind-foot is also three-toed,
and there is a trace of the hallux. The fingers are so widely separated and
divergent from each other that it has been suggested that the animal had
webbed feet and inhabited marshes, in which it swam by the aid of its long
tail. The creature was the size of a Tapir.

Closely resembling _Anoplotherium_ are a number of other genera.

_Diplobune_ ( = _Hyracodontotherium_) was much like the last, but was a
more delicately-formed animal. The fingers and toes (three of each) end in
such sharply-pointed phalanges that claws seem to be almost suggested.
There are several species of this genus. _Dacrytherium_ differs by the
presence of a lachrymal fossa.

_Dichobune_ has four-toed extremities, of which the lateral ones are more
slender and shorter than the two middle ones. As in other Anoplotheriidae,
the anterior premolars are furnished with a sharp cutting edge.

ORDER V. SIRENIA.

Aquatic Mammalia, with but few scattered hairs; hind-limbs absent;
fore-limbs paddle-shaped; tail flattened, and either {334} Whale-like or
rhomboidal to circular in form. Nostrils on upper surface of not
specially-elongated snout. Clavicles are absent. The scapula has the normal
mammalian form, with a well-developed and roughly median spine. The bones
of the arm and hand articulate together, as in land animals; the phalanges
show at most traces of increase in number above the normal. Pelvis
represented by a vestige, more highly developed in some fossil than in
recent forms. Stomach complex, consisting of several chambers. Lungs simple
and not lobulated. Diaphragm oblique and very muscular. Brain peculiar in
form and but slightly convoluted. Testes abdominal. Teats two, and pectoral
in position. Placenta non-deciduous and zonary.[222]

This limited group consists of purely aquatic forms, which are both marine
and fresh-water in their proclivities. They have been placed in the
immediate vicinity of the Whales; but it is now believed by most zoologists
that the likenesses which they undoubtedly show to the Cetacea are of an
adaptive kind and related to their similar mode of life. The group is a
readily-definable one. Externally they are marked by their dark coloration,
somewhat Whale-like though of clumsier build, and by the total absence of
external ears and hind-limbs; the latter are, however, as will be pointed
out shortly, marked by certain rudimentary bones. There is a flattened
tail, which in the Dugong and _Rhytina_ is precisely like that of a Whale.
It is interesting to note that the former genus, whose tail is, judging it
at least by the standard of the Whales, more completely modified for the
aquatic life, should also show other features which indicate their longer
life as marine creatures. For the flippers are more Whale-like in that the
fore-arm is completely enclosed within the body, or nearly so, and the
nostrils have a more decidedly superior position than in the Manatee. The
fore-limbs of this group, as may be inferred from what has just been said,
are flipper-like; but, contrary to what we find in Whales, the phalanges do
not as a rule show any traces of multiplication, so characteristic a
feature of the Cetacean hand, and the individual bones are connected by
well-formed joints. Beneath the thick skin, which is sparsely provided with
stout hairs in the Dugong, is a layer of blubber. Dr. Murie has called
attention to the fact that this layer in the {335} Manatee[223] differs
from the blubber of the Whale in that there is no free oil anywhere.[224]

The skeleton of the Sirenia is strong and massive, thus contrasting with
the loosely-textured bones of the Cetacea. The cervical vertebrae are, as a
rule, free, but the second and third are fused in _Manatus_ and the extinct
_Halitherium_. It is noteworthy that in _Rhytina_ the cervical vertebrae
have the exceedingly thin centra that characterises the neck vertebrae in
Whales. The ribs are most of them firmly articulated by two heads. The
breastbone is generally reduced, as in Whales; and but few ribs are
attached thereto. The vertebrae, moreover, are well locked together by
zygapophyses, and not loosely attached as in Whales.

The shoulder blade is long and narrow, and not unlike that of the Seals. It
is totally unlike the peculiarly-modified scapula of the Whale tribe. But,
as in the latter, there are no clavicles.

The hind-limbs are only represented by the pelvis; and this is a
rudimentary structure, varying, however, in the degree of its degeneration.
That of the extinct _Halitherium_ recalls the pelvis of the Rorqual. There
is a single triradiate bone with an acetabular cavity for the rudiment of
the femur in the centre; it suggests that here the three normal elements of
the pelvis have become fused into a single bone. In the Dugong there are
two small bones on each side.

The Manatees (_Manatus_)[225] are found in the fresh-waters and along the
Atlantic coasts of South America and Africa. It appears that there are four
species, of which one only is African, the others American. Report asserts
the former occurrence of this genus on the shores of St. Helena.

The Manatee is provided with only six cervical vertebrae, a fact which
distinguishes it from the other existing genera of its group. A remarkable
feature which it exhibits is the large number of molar teeth. These
apparently go on increasing indefinitely during its life, the suggestion
being that they are worn away by the nature of the food--algae with much
sand intermixed. As many as twenty molar teeth have been counted in one
half of the jaw, and there is no reason to forbid the assumption that they
{336} may get still more numerous. This large number of grinding teeth is
obviously suggestive of the Whales, with which the Sirenia are believed by
some to be allied. It is at least a remarkable coincidence that these two
aquatic groups of mammals should both have assumed the same indefinite
tooth formula. It is correct to say assumed, since extinct forms of
Manatees, such as _Halitherium_ and _Prorastoma_, have not a continuous
succession of molars. The brain of the Manatee is, contrary to the usual
arrangement among aquatic mammals, smooth, and only marked by one or two
fissures.

The Manatee[226] is black in colour, its thick skin being wrinkled. The
animal is assisted in feeding by a curious mechanism of the upper lip; this
is split in two, and the two halves, which are furnished with strong
bristles, can play upon each other like the points of a pair of forceps.
The flippers are furnished with nails, save in _M. inunguis_, but in the
nailed forms it is not every finger which is thus armed.

[Illustration]

FIG. 179.--Skeleton of Dugong. _Halicore australis._ (After de Blainville.)

_Halicore_,[227] the Dugong, is an entirely Oriental and Australian {337}
form; there appears to be but a single species, though more than one name
has been given to supposed distinct species. As already mentioned, it
differs from the Manatee in the possession of a Whale-like tail; the
nostrils, too, are more upon the upper surface of the head, and there are
no nails upon the flipper. The peculiar cleft lip of the Manatee is not so
well developed in the Dugong, but there are traces of it; and in the foetus
the likeness to the Manatee in this respect is very striking. It would thus
appear that _Halicore_ is a stage in advance upon _Manatus_; that the
remarkable mechanism of the lip of the latter has been possessed, but has
been lost, by the Dugong. The skull of the Dugong is distinguished by the
stout premaxillary bones, which bear a tusk in the male. In the female the
tooth is there, but is lodged within the bone. This incisor has a milk
forerunner. The back teeth of the Dugong (there are no canines) are few in
number (four or five, even six), thus showing a gradual reduction when
compared with _Manatus_; and this culminates in the toothless _Rhytina_. It
is also interesting to notice that in the massive lower jaw there are
traces of an incisor. Were this to be developed into a tusk, the jaw would
present a curious resemblance to that of _Dinotherium_.

The Dugong, _H. dugong_, has the reputation of being the original of the
mermaid legends, since the young is held to the pectorally-situated breast
with one flipper. "But it should be remembered," justly observes Dr.
Blanford, "that stories of beings half man or woman, half fish, are as
common in temperate as in tropical seas, and that some of them are more
ancient than any European knowledge of the Dugong."

EXTINCT SIRENIANS.--The earliest genus that can be with certainty referred
to this order is the Oligocene _Prorastoma_. This genus, though offering no
particular skull-characters that assist in the determination of the
much-debated affinities of the Sirenia, shows a remarkable condition of the
teeth that may afford a clue. The species _P. veronense_, recently
described by Mr. Lydekker,[228] is founded upon a fragment of the skull
which contains two teeth apparently representing the third and fourth upper
milk molars. The interest attaching to these teeth lies in the fact that
they clearly exhibit the buno-selenodont condition characteristic of
certain early Artiodactyles, e.g. _Merycopotamus_.

_Halitherium_ is a later genus, which is known by the nearly {338} complete
skeleton. The skull is like that of other Sirenia, with the down-turned
premaxillary region. But the nasal bones, lost, or at least rudimentary, in
recent forms, are well developed; the likeness of ancient to living forms
in this respect being exactly paralleled by the Zeuglodonts, when compared
with recent Whales. The vertebral centra exhibit distinct epiphyses, which
have disappeared in living Sirenians. The cervical vertebrae are seven, of
which the second and third are occasionally fused. There are nineteen pairs
of ribs, and there are three lumbar vertebrae. The sternum consists of
three separate pieces. There is a rudimentary femur.

The recently-extinct Steller's Sea-cow, belonging to the genus _Rhytina_,
was a huge beast, seen in the flesh up to nearly the end of the last
century. It frequented the shores of Bering's Straits. Its remains occur in
the peat on the shores of those seas. It reaches a length of some 20 to 30
feet. The external characters were much like those of other recent
Sirenians. The nostrils were above the fore part of the snout, the latter
being truncated and obtuse. The tail was of the Cetacean pattern, and thus
like that of _Halicore_. The head of this Sirenian was small, and the teeth
had entirely vanished save for the apparent existence as transitory
structures of two small incisors in the upper jaw. The absence of teeth was
compensated by the presence of a horny palate for the trituration of the
sea-weeds which constituted the food of Steller's Sea-cow. The fore-limbs
seem to have possessed no nails, but were covered at the extremity with
short, bristly hairs, no doubt serving the purpose of keeping the animal
moored in safety to the slippery beds of Fucus upon which it browsed.

There are nineteen pairs of ribs. The vertebrae of the cervical region are
the customary seven, and the centra are thin and plate-like as in the
Cetacea, the animal being thus short-necked like those marine creatures.

       *       *       *       *       *


{339}

CHAPTER XII

CETACEA--WHALES AND DOLPHINS

ORDER VI. CETACEA.[229]

Aquatic Mammalia of fish-like form; tail expanded into horizontal flukes; a
fatty dorsal "fin" present in most species; anterior limbs converted into
fin-like paddles; posterior limbs only represented by skeletal rudiments.
Hairy covering reduced to a few isolated hairs in the neighbourhood of the
muzzle. Nostrils represented by the single or double blow-hole, nearly
always situated far back upon the skull. Bones of loose texture and much
impregnated with oil. The skull has a greatly-developed facial portion;
supra-occipital bones meeting the frontal by overgrowing, or growing in
between the parietals; bones surrounding the organ of hearing loosely
attached to the skull, the tympanics of peculiar cowrie-shell form.
Coronoid process of mandible absent, or very feebly developed. Teeth, when
present, few or numerous, always of simple conical form, with at most
traces of additional cusps (_Inia_); if absent their place taken by
whalebone. Cervical vertebrae of short antero-posterior diameter, often
more or less completely welded together into a single mass. Articulations
between dorsal and other vertebrae feeble. Scapula peculiarly flattened;
acromion strongly developed as a rule, but arising from a slightly-marked
spine; coracoid process generally strongly developed. Phalanges of digits
always more numerous than in other mammals. Clavicles absent. Stomach
complex, consisting of at least four and often more chambers. Lungs simple
and non-lobulated. Diaphragm obliquely set and very {340} muscular. Brain
much expanded transversely and well convoluted. Testes abdominal. Teats
two, inguinal in position. Placenta diffuse and non-deciduate.

The Whales and Dolphins, which constitute this order, form an assemblage
which is easily characterised by reason of the fact that their affinities
to other groups of Mammalia are so doubtful that they furnish matter rather
for speculation than for authoritative statement. Some hold that they
resemble in certain points the Ungulata; while others again see in them the
culminating term of a series which commences with such a form as the Otter,
and of which the Seals and Sea-lions are intermediate stages. A third
opinion is that the Whales have arisen from some low mammalian stock, too
primitive to be assigned to any existing order of mammals. Palaeontology,
as will be seen later, throws no light whatever upon their origin. This
matter has already been referred to (see p. 120) in considering the
position of the Cetacea.

The Whales include the most gigantic of all the orders of vertebrated
animals. No creature living or extinct is so large as the Sibbald's
Rorqual, which attains to a length of some 85 feet, or perhaps even rather
more. On the other hand we have what are by comparison minute forms. Apart
from the possibly problematical _Delphinus minutus_, stated to be only 2
feet in length, we have as a minimum 3 or 4 feet. The size of the Cetacea
has been subjected to much exaggeration. The first duty of a Whale,
observed the late Sir William Flower, is to be large; and Natural
Historians, in the recent as well as in the remote past, have not hesitated
to put very round numbers upon the dimensions of the larger members of the
order. We may perhaps pass over Pliny's "fish called balaena or whirlpool,
which is so long and broad as to take up more in length and breadth than
two acres of ground," and a number of analogous exaggerations, which
gradually dwindled down to the dimensions just stated of the great Rorqual.
M. Pouchet has made the ingenious suggestion that the statements of the
ancients may have been nearer the truth than observations of to-day would
have us believe; he pointed out justly that in former times Whales were not
so relentlessly pursued as during the last century; the inference being
that they may have lived to a greater age, and attained a more colossal
bulk. The more modern exaggerations in the {341} dimensions of the bigger
Whales are probably due to the fact that measurements have been taken, not
in a straight line from snout to tail, but along the bulging sides of the
Cetacean, rendered even more convex than in nature by decomposition, and by
pressure due to the immense tonnage of the creature.

The Cetacea are the most perfectly aquatic of all mammals; they never leave
the waters which they inhabit. It is true that legends have represented
them as pasturing upon the shore--Aelian spoke of Dolphins basking in the
sun's rays upon the sand; and the "Devil Fish" of California,
_Rhachianectes_ (see p. 357) has given rise to improbable stories--but they
are apparently only legends. Indeed a stranded Whale cannot live long, for
it is unable to breathe, the comparatively feeble breast being crushed by
its own weight. In accordance with the purely aquatic habit, we find a
modification of the outward form of the body (and as we shall see later of
many of the internal organs), which renders the Cetacea externally unlike
all other mammals. The form is fish-like, the fore-limbs are paddles, the
tail is expanded into two horizontal flukes, which serve to propel the
creature through the water.

[Illustration]

FIG. 180.--Killer. _Orca gladiator._ × 1/40 (After True.)

The skin is smooth and shiny, so smooth and so shiny that it has often been
compared to coach leather. But nevertheless they are not entirely without
that most essential character of the class Mammalia, a coating of hair. The
hairy covering is, however, reduced to the very smallest proportions; it is
represented {342} by a few hairs only--so few that they can be counted with
ease--in the neighbourhood of the muzzle. These hairs are not present in
all Whales; they are absent, for example, in the White Whale or Beluga.
When present they are not furnished either with sebaceous glands or with
muscular fibres, which are such universal concomitants of the hair
follicles in the Mammalia generally. This appears to be conclusive evidence
that the hairs, few as they are, are still undergoing degeneration. The
need for a furry coat is removed by the presence of a thick coating of fat
immediately underlying the skin. This is known as the blubber, and is the
main incentive to the pursuit of Whales. It must not, however, be assumed
without further argument that the hair is absent because its place is
taken, as a mechanism for retaining the heat, by the blubber; for the Seal
tribe possess both fur and blubber. Another conceivable explanation is
quite at variance with such a view of economy. It may be noticed that among
Ungulates there is a tendency to lose hair, particularly among more or less
aquatic forms. Thus the Hippopotamus is almost naked (as is indeed the
Walrus); the Rhinoceros, too, often a frequenter of marshy soil, is almost
as denuded as is the Hippopotamus. It is not, however, settled that the
Whales have anything to do with the Ungulata; otherwise an additional
argument might be used, that is, the secular loss of hair in some members
of this group. The Hairy Rhinoceros, _Rh. tichorhinus_, was, as its name
denotes, a hairy beast; the Mammoth was equally so. The descendants, or at
least the modern representatives of both these creatures, are but scantily
clad with hairs.

A final reason for the naked character of the skin in existing Cetacea is
closely connected with a feature in the organisation of three or four
living species which must first be described.

Some years ago the late Dr. J. E. Gray of the British Museum described from
the sea, off Margate, what he considered to be a new species of Porpoise,
characterised by the presence on the dorsal fin of a row of stony
tubercles. As a matter of fact it was subsequently shown that the Common
Porpoise has the same structures, so that there was no need for a Margate
species, _Phocaena tuberculifera_. Moreover, in the Indian _Neomeris_, a
close ally of the Porpoise, a more abundant calcified covering of scales
exists along the whole back of the animal. These plates, {343} it has been
discovered, are larger in the foetus, a fact which naturally points to
their being an inheritance from the past, now undergoing retrogressive
changes. Such a way of looking upon the facts is confirmed by the finding,
many years ago, by the naturalist and physiologist Johannes Müller, of bony
plates in connexion with the remains of a Zeuglodont Cetacean. It looks,
therefore, very much as if the Eocene ancestors of the modern Cetacea had a
skin studded with bony plates, as have the armadillos. This being the case,
the disappearance of hair is not surprising. The room would be taken up by
the calcified plates, and when the latter disappeared, as they have in the
vast majority of existing Whales, the naked skin alone would be left.

Whales possess no externally-visible hind-limbs; rudiments of these
appendages are present, which will be dealt with under the description of
the principal features of the skeleton. But it has been discovered that in
the Porpoise, external vestiges of hind-limbs do appear in the foetus, a
fact which, be it observed, does away with the old view that the flukes of
the Whale are the last term in the series of vanishing hind-limbs, of which
the Seals, with their hind-limbs and tail bound up together, offer an
intermediate step.

The tail is fish-like in form, but the flukes are horizontal instead of
vertical as in fishes and _Ichthyosaurus_. This arrangement is no doubt
associated with the need for rapid return to the surface waters after a
prolonged immersion in search of food. A downward stroke, such as is given
by the powerful and large tail flukes, would naturally bring about this
result rapidly. The tail, moreover, is under all circumstances the swimming
organ. Its motion has been stated to be slightly rotatory, like that of a
screw, and it is the case that the two flukes are often alternate in shape
like the flanges of a screw; one being convex upwards, the other convex
downwards.

The fore-limbs are in the form of paddles, but they do not apparently serve
as organs of locomotion so much as balancers. When a Whale is killed, it
falls over on to one side, the office of the flippers being to maintain the
proper position. It is believed, however, from the fact that the embryo
often shows a relatively larger pectoral fin than that of the adult--the
difference being due to a reduction in the adult of the number of
phalanges--that the fin was once an organ of progression. {344}

The pectoral fin of Whales exists in two forms. In the Toothed Whales it is
shorter and rounder; in the Whalebone Whales longer and narrower.
Structural differences accompany these outward dissimilarities. In the
first-named group the humerus and the beginning of the radius and ulna are
within the body, and do not form a part of the fin. In the Whalebone
Whales, on the other hand, the fin contains all the bones of the fore-limb.
Another remarkable contrast between the hand in the two groups of Whales is
that while the Toothed Whales have five fingers, thus justifying the
prevailing opinion that they are the more primitive of the two groups, the
Whalebone Whales have only four fingers. Actually the Right Whale,
_Balaena_, seems to have five fingers; and, indeed, the fact that it has,
is often used to distinguish it from the Humpback, which has undoubtedly
only four. But a careful consideration of the state of affairs which
prevails in the foetus of _Balaenoptera_ dispels this idea. Between what
are apparently the second and third fingers, a rudimentary finger,
consisting of four phalanges, appears. This is not produced, as is an
additional finger found in the White Whale or Beluga, by a splitting of a
finger. Accordingly the four-fingered condition of the Whalebone Whales is
produced by the dropping out of a finger in the middle of the series,--a
very remarkable fact. When fingers disappear, as, for instance, in the
Horse, etc., it is at the two ends of the series that the digits vanish. If
this view of Professor Kükenthal's[230] be accepted, it follows that the
presumed thumb of the Right Whale is what has been termed the prepollex.

The hand of the Whales, like those of some other aquatic creatures, _e.g._
the reptile _Ichthyosaurus_, has a larger number of phalanges than have
terrestrial animals. The result of this is, of course, to increase the
length of the fin and its utility as a paddle. It is commonly not all the
fingers that have developed this great number of accessory phalanges.
Rudimentary nails have been found upon the Cetacean hand; but in no case
are they functionally developed. In the Manatees we have the disappearance
of the nails still imperfectly accomplished. In _M. latirostris_ there are
nails; these have vanished, apart from possible traces to be seen with a
microscope, in _M. inunguis_.

A very characteristic feature of certain Whales are the furrows {345} to be
seen on the throat. This is especially the case with the Rorquals, in which
group the Humpback Whale, _Megaptera_, is to be included. The whales of
these two genera (_Balaenoptera_ and _Megaptera_) have a large number of
the throat furrows--as many as sixty have been counted. Some other Whales
have a smaller number; thus _Rhachianectes_ has but two on each side, and
the Physeteridae have not many more. These furrows are absent in very young
embryos. It is thought by Professor Kükenthal that they allow of a wide
opening of the mouth.

[Illustration]

FIG. 181.--Dorsal surface of bones of right anterior limb of Round-headed
Dolphin (_Globicephalus melas_). × 1/10. The shaded portions of the digits
are cartilaginous. _c_, Cuneiform; _H_, humerus; _l_, lunar; _R_, radius;
_s_, scaphoid; _td_, trapezoid or magnum; _U_, ulna; _u_, unciform; _II-V_,
digits. (From Flower's _Osteology_.)

The blow-hole of Whales is, of course, the aperture of the nostrils, which
are not so far back in the foetus as in the adult. By the characters of the
nostrils the Toothed Whales can be distinguished from the Baleen Whales; in
the latter the orifice is double, in the former single. In embryos of
Dolphins, however, the two apertures are quite independent. The phenomena
of spouting have often been misinterpreted.[231] When the Whale breathes,
the expired air rushes out through the nostrils. The water vapour in the
breath condenses into drops of water in the cold Arctic regions where the
phenomenon has been mainly observed. Hence the idea that water taken in at
the mouth is expelled through the blow-hole. As the Whale approaches the
surface to breathe, it may be that some of the water of the sea is {346}
driven upwards by the forcible expulsion of air from the lungs. But for the
most part the water which is spouted is simply condensed breath.

Like some, but not all, other aquatic Mammalia the Whales have apparently
no external ear. Indeed the opening of the ear is excessively small. In a
huge Rorqual it will "admit a quill"; and although "a quill" is rather
vague, we may fairly allow any sized quill without proving that the orifice
of the auditory passage is anything but exceedingly minute. As a proof,
added to so many, that the Whales are the progeny of terrestrial creatures,
we have the occasional traces of external ears.[232]

[Illustration]

FIG. 182.--Left lower jaw of foetus of _Balaenoptera rostrata_. Inner
aspect, natural size, showing teeth. (After Julin.)

Whalebone Whales never possess permanent teeth as well as the baleen; but
in the foetus are more than traces of true teeth, which, however, never
arrive at maturity. The whalebone itself is described later (p. 354). That
the Whalebone Whales possess teeth while in the foetal condition was
discovered so long ago as 1807. It has since been confirmed by many
observers. Not only is there one set of teeth developed in the foetal
_Balaenoptera_ but two, of which one comes to a greater maturity; the
other, in fact, remaining at a very early stage of development. The more
complete dentition belongs to the milk series, as is the case with the
Toothed Whales. A very interesting conclusion with regard to the derivation
of the simple conical teeth of Whales seems to follow from the development
of these structures in Balaenoptera. There are in the young foetus fewer
teeth than in the more advanced embryo. Now in the younger embryo some of
the teeth are furnished with more than one cusp; they are bi- or even
tri-conodont. As Sir R. Owen observed, the teeth--some of {347} them--are
literally double teeth. This is a suggestion of the more complicated teeth
of the Zeuglodonts, and shows so far that the simple conical teeth of
existing Whales (cf. however the Platanistidae) are not by any manner of
means so primitive as their actual structure would undoubtedly lead one to
believe. Further than this, the greater number of teeth in the older embryo
coincided with the disappearance of these double teeth, which seem to split
up into the simple conical teeth.

The Toothed Whales are not furnished with baleen, but with teeth only.
These teeth are more or less numerous, their arrangement being of value in
the classification of the group; a matter which is dealt with later.

In the Narwhal, whose dentition in the adult is reduced to the well-known
tusk or tusks (properly developed only in the male), there is a complete
foetal dentition. A very curious fact has been elucidated by Professor
Kükenthal about the dentition of the Common Porpoise. It appears that in
this Cetacean the two teeth corresponding to each other of the two
dentitions may fuse into a single tooth, which has in consequence a double
crown. It may be that this is the case with the Platanistid _Inia_, and
that its diconodont teeth are not, therefore, a reminiscence of the
comparatively complicated teeth of the ancient Zeuglodonts.

The internal organs of Whales which show the greatest peculiarities as
compared with other mammals are the stomach, the lungs, and the diaphragm.
Whales always possess a complicated stomach divided into many, but into a
variable number of, chambers: there are as few as four in some, as many as
fourteen in Ziphioids.

On account of its complication the stomach[233] has been compared to that
of Ruminants--it has even been alleged that Whales "ruminate"--but the
comparison will not hold good. Nor, on the other hand, is there a very
close resemblance to the equally-complicated stomach of the Sirenians.

The Rorqual has a stomach with as few compartments as any. The only Whale
which appears to have fewer is _Balaena mysticetus_, where there are but
three. In the Rorqual the oesophagus opens into a more or less globular
sac; from the upper end of this, _i.e._ close to the entry of the
oesophagus, arises the second chamber, long and narrowish; then follows an
extremely short third sac, {348} then a larger fourth, after which comes
the dilated commencement of the small intestine. The latter might be
regarded as a chamber of the stomach were it not for the fact that the
ducts of the liver and the pancreas open into it. This represents one type
of the Cetacean stomach, which seems to be found in all Whales except the
Ziphioids. In the latter, the oesophagus opens into the first compartment
as usual; but the second division of the stomach arises not close to the
entrance of the oesophagus, but at the opposite end. It would seem,
therefore, as if the first division of the stomach, found in most Whales,
were missing in Ziphioids. This way of looking at the matter is confirmed
by the fact that in _Hyperoodon_ a remnant of the missing first stomach is
found in the shape of a small diverticulum of the oesophagus just before it
enters the stomach.

The essential difference between the Whale's and the Ruminant's stomach is
this: in the latter the stomach is primarily divided into two portions, of
which the first is non-digestive and is clothed with oesophageal
epithelium. The second, the abomasum, is the digestive region. The first
part is again divided into three compartments. In the Whales, on the other
hand, it is the digestive part which is again subdivided, while if the
first part is divided it is not markedly so as in the Ruminants.

The lungs are remarkable for their unlobulated character; in this they
agree with the lungs of the Sirenia. The thoracic cavity in which they lie
is barrel-shaped, and not, as is usual in terrestrial mammals, boat-shaped,
_i.e._ narrower sternally than above. The alteration of the shape of the
thoracic cavity is associated with the aquatic life; so at any rate the
fact that it is also marked in Seals and even in the Otter seems to show.
The Whales are also characterised by the great obliquity of the diaphragm,
which is extremely muscular. In this character again we find an agreement
with the Sirenia, and also with other aquatic mammals; it is not therefore
a character of Whales so much as evidence of an adaptation to the aquatic
life. The advantage is, it appears, in the increased capacity of the
thoracic cavity, and the consequent greater possibilities of expansion of
the lungs, which it must be remembered serve as hydrostatic as well as
breathing organs.

Some of the internal arteries of Whales break up into retia mirabilia.
Their kidneys are lobulated; whether this has {349} anything to do with the
aquatic life is not so clear. It also characterises the Sirenia, more or
less, and the Otters; but, on the other hand, the terrestrial Bears show
the same structure as do also some Ungulates. It must be borne in mind,
too, that the kidneys of foetal Man are lobulated.

The liver is a compact organ not showing such lobulation as is common, but
not universal, among mammals.

The bones of Whales have a somewhat loose structure, and are much
impregnated with oil. In many features the skeleton of Whales is highly
distinctive of the order.

[Illustration]

FIG. 183.--Skeleton of Porpoise (_Phocoena communis_), _acr_, Acromion
process of scapula; _cerv_, united cervical vertebrae; _chev_, chevron
bones; _cor_, coracoid process; _hu_, humerus; _hy_, hyoid; _jug_, jugal;
_lumb.trans_, lumbar transverse processes; _max_, maxilla; _nas_, nasal;
_orb_, orbit; _par_, parietal; _pelv_, vestige of pelvis; _per.ot_,
periotic; _pr.max_, premaxilla; _rad_, radius; _rb_^1, first rib;
_rb^{12}_, twelfth rib; _sc_, scapula; _s.occ_, supra-occipital; _st_,
sternum; _uln_, ulna; _zyg_, prezygapophysis. (From Parker and Haswell's
_Zoology_.)

[Illustration]

FIG. 184.--Under surface of the cranium of a young Caa'ing Whale
(_Globicephalus melas_). × 1/5. _AS_, Alisphenoid; _BO_, basioccipital;
_cf_, condylar foramen; _ExO_, exoccipital; _Fr_, supra-orbital process of
frontal; _gf_, glenoid fossa of squamosal; _Ma_, body of malar; _Mx_,
maxilla; _OS_, orbitosphenoid; _Per_, posterior (mastoid) process of
periotic; _Pl_, palatine; _PMx_, premaxilla; _Pt_, pterygoid; _Sq_,
squamosal; _tg_, deep groove on squamosal for meatus auditorius externus,
leading to tympanic cavity; _Ty_, tympanic; _Vo_, vomer; _ZM_, zygomatic
process of malar. (From Flower's _Osteology_.)

The brain case is small proportionately and rounded. The "face" is
therefore long, and in some cases, especially among the fossil forms of
Platanistidae, the rostrum is extraordinarily elongated. The asymmetry of
the Whale's skull is one of its most remarkable features; this, however, is
entirely limited to the Toothed Whales, and among them is more pronounced
in some forms than in others. Thus the Platanistidae and many Ziphioids are
not nearly so asymmetrical as the {350} Dolphins and, especially,
_Physeter_. This asymmetry affects particularly the premaxillae, the
maxillae, and the nasals. The base of the skull is symmetrical. The Whale's
skull has very long premaxillae which, however, do not, except in the
extinct Zeuglodonts, bear any teeth. The nasal bones, whether symmetrical
or the reverse, are very small in existing Whales, which arrangement,
together with the long and broad maxillary bones, removes the anterior
nostrils, the blow-hole, far backwards. The roof of the skull is not at all
formed by the parietals externally. These bones form a portion of the side
of the cranium, but are replaced or covered by the {351}
enormously-developed supra-occipital in the adult. Here again the
Zeuglodonts are more typically Mammalian, for in them the parietals have a
normal development and situation, rising even into a median crest as in so
many quadrupeds. The bones related to the organ of hearing, the tympanis
and petrous bones, are very solid and dense in structure. Moreover they are
but loosely attached to surrounding bones, and are thus easily and
frequently lost. Nearly the only mammals which resemble the Whales in the
fact that the pterygoids sometimes meet in the middle line below are the
Edentata (Anteater and Armadillo, see p. 167). But in both groups this
peculiarity is not universal.

[Illustration]

FIG. 185.--A section of a skull of a young Caa'ing Whale (_Globicephalus
melas_). × 1/5. _a_, Angle; _an_, anterior nares; _AS_, alisphenoid; _bh_,
basihyal; _BO_, basioccipital; _BS_, basispnenoid; _cd_, condyle; _cp_,
coronoid process; _ExO_, exoccipital; _Fr_, frontal; _id_, inferior dental
canal; _IP_, interparietal; _ME_, ossified portion of the mesethmoid; _Mx_,
maxilla; _Na_, nasal; _Pa_, parietal; _Per_, periotic; _Pl_, palatine;
_PMx_, premaxilla; _pn_, posterior nares; _PS_, presphenoid; _Pt_,
pterygoid; _s_, symphysis of mandible; _sh_, stylohyal; _SO_,
supra-occipital; _Sq_, squamosal; _th_, thyrohyal; _Vo_, vomer. (From
Flower's _Osteology_.)

The vertebral column is remarkable for the fact that more or fewer of the
cervical vertebrae may be fused together into a short and compact mass.
This is seen at its maximum in the genera _Balaena_ and _Neobalaena_. The
odontoid process of the second {352} vertebra, though hardly at all marked,
is nevertheless really present and developed from a bony centre of its own,
as in other mammals. The dorsal and lumbar vertebrae are, of course, to be
distinguished by the presence of ribs attached to the former; but as there
is only a rudimentary pelvis, not attached to the vertebral column, no
sacral region can be detected. The caudal vertebrae are to be recognised by
the [234]-shaped chevron bones below.

[Illustration]

FIG. 186.--Section through middle line of united cervical vertebrae of
Greenland Right Whale (_Balaena mysticetus_). × 1/9. _a_, Articular surface
for occipital condyle; _e_, epiphysis on posterior end of body of seventh
cervical vertebra; _sn_, foramen in arch of atlas for first spinal nerve;
1, arch of atlas; 2, 3, 4, 5, 6, conjoined arches of the axis and four
following vertebrae; 7, arch of seventh vertebra. (From Flower's
_Osteology_.)

[Illustration]

FIG. 187.--A, Sternum of Greenland Right Whale (_Balaena mysticetus_). ×
1/15. B, Sternum of Common Rorqual or Fin Whale (_Balaenoptera musculus_).
× 1/10. (From Flower's _Osteology_.)

The sternum in the Whale tribe is much more modified in the Whalebone
Whales than in the Odontocetes. In the latter it is made up of several
pieces, as in other mammals, which often, however, become coalesced. In the
Mystacoceti this bone is a single piece, to which only one pair of ribs is
attached, and its {353} form is characteristic of the genus. It is
heart-shaped, more or less, in _Balaena_, and somewhat cross- or
[235]-shaped in the genus _Balaenoptera_. In the Odontocetes the ribs have,
some of them, the normal attachment by capitulum and tuberculum. In the
Mystacocetes the attachment, where it exists, is very loose, and the
tuberculum alone is attached to its vertebra. This allows of the freer play
of the ribs during respiration. The scapula has a very characteristic form
in these animals. The acromion, where it exists, is placed near the
anterior margin of the shoulder blade, and overlaps the generally long
coracoid process. Clavicles are totally absent. The pelvis is very
rudimentary, consisting merely of a single bonelet, to which are attached
the rudiments (in some cases) of a femur, and, in _Balaena_ (Fig. 188), of
a tibia also.

[Illustration]

FIG. 188.--Side view of bones of posterior extremity of Greenland Right
Whale (_Balaena mysticetus_). × 1/8. _i_, Ischium; _f_, femur; _t_,
accessory ossicle representing the tibia. (After Eschricht and Reinhardt)
(from Flower's _Osteology_.)

Whales are to be divided into three great groups:--(1) the Whalebone Whales
or Mystacoceti; (2) the Toothed Whales or Odontoceti; and (3) the
entirely-extinct Archaeoceti or Zeuglodonts.

SUB-ORDER 1. MYSTACOCETI.

This division is thus characterised:--Teeth are never functionally
developed; they are present in the young, but replaced in the adult by the
baleen or whalebone; the external respiratory aperture is double; the skull
is perfectly symmetrical; the rami of the mandible are arched outwards and
do not form a true symphysis; the sternum is always composed of a single
piece of bone; the ribs articulate only with the transverse processes of
the vertebrae.

The Mystacoceti are nearly invariably huge creatures, the sole exceptions
being the Pygmy Right Whale, _Neobalaena_, and {354} a small Rorqual. But
even these are larger than the majority of Toothed Whales.

The most characteristic feature by which the Whalebone Whales are to be
distinguished from other Whales is that which gives to them their name, the
presence of whalebone. Whalebone is a horny product of the epithelium
lining the mouth, and is comparable to an exaggeration of the transverse
ridges which are found in the mouths of all mammals upon the palate. In
non-Cetacean mammals these ridges vary in depth, and are arranged as a rule
transversely, but with an oblique inclination. This is precisely how the
plates of baleen are disposed in the mouth of a Whale. Each piece of "bone"
is triangular in shape, the broader end being that of attachment while it
narrows gradually; the inner side of the blades is frayed out into a number
of threads which form the straining apparatus. The plates vary in length up
to as great an extreme length as 13 feet, which occurs in the Right Whale
at times. The colour is black or paler, even white. The number of these
plates in the mouth is very great. As many as 370 blades have been counted.
They diminish in length towards both ends of the series. Though whalebone
has been in use for a long period, whence the whalebone came was formerly
one of those things not generally known.

[Illustration]

FIG. 189.--Section of upper jaw, with baleen plates, of _Balaenoptera_.
_a_, Bone of jaw; _b_, gum; _c_, straight edge of baleen plate; _d_, _e_,
frayed out surface of baleen plates. (After Owen.)

A very prevalent notion was that the whalebone formed the eyelids or
perhaps the eyelashes of the creature. Scaliger, commenting upon Aristotle,
held that the whale had "lamellae upon the eyebrows, which, when the head
is plunged below the surface, were raised by the water; but when the animal
raised its head {355} above the waves the lamellae fell and covered the
eyes." Whalebone, too, has been often spoken of as "the fin of a whale,"
"the finnes that stand forth of their mouths." The value of whalebone is
still great, in spite of various substitutes which are now used in its
place. In the year 1897, for example, the value of this article was £2000
per ton. As a single Whale may produce several tons of this material, it is
not surprising to find that the results of a whaling voyage may be very
profitable.

FAM. 1. BALAENOPTERIDAE.--This genus _Balaenoptera_ includes the Rorquals,
which are Whalebone Whales of large size, differing from the Right Whales
in three important external characters: the head is comparatively small;
there is a dorsal fin; the throat is marked by numerous longitudinal
furrows. The bones of the cranium are not so arched as in the Right Whales,
and as a consequence the plates of baleen are shorter. The hand is only
four-fingered. The cervical vertebrae are for the most part all free. One
of the earliest records of a Whale stranded in the Thames was probably of a
species of this genus in the year 1658, and is thus described by John
Evelyn:--"A large whale was taken betwixt my land butting on the Thames and
Greenewich, which drew an infinite concourse to see it, by water, horse,
coach, and on foot, from London and all parts.... It was killed with a
harping yron, struck in the head, out of which spouted blood and water by
two tunnells, and after an horrid grone it ran quite on shore and died. Its
length was 58 foot, heighth 16; black skinn'd like coach leather, very
small eyes, greate taile, onely two small finns, a picked snout, and a
mouth so wide that divers men might have stood upright in it; no teeth, but
suck'd slime onely as thro' a grate of that bone which we call whalebone,
the throate yet so narrow as would not have admitted the least of fishes
... all of it prodigious, but in nothing more wonderful that an animal of
so greate a bulk should be nourished onely by slime thro' those grates."

Professor Collett has recently given[236] an elaborate account of the
characters and habits of this great Whale (_Balaenoptera musculus_). Though
a large beast (44 to 67 feet in length) it is exceeded by other Rorquals;
it is of a dark grey blue colour above, white, for the most part, below.
The dorsal fin is large and high; the flippers relatively slender and
small. The whole throat from the {356} symphysis of the jaws to the middle
of the belly is, as in other species, marked by furrows, forty to
fifty-eight in number. The hairy covering is reduced (in an adult female)
to thirteen hairs on each side of the lower jaw; in a foetus there were
also seven hairs on each side of the upper jaw, as well as rather more on
the lower jaw--altogether, forty-eight. This Whale appears to feed chiefly
upon small Crustacea, especially the Copepod, _Calanus finmarchicus_. The
number of baleen plates is about 330 on each side of the jaw. This Whale
sometimes swims singly, but usually in schools of even as many as fifty.

Rudolphi's Rorqual (_B. borealis_) seems to be a perfectly inoffensive
beast; it is said to be able to stay under water for as long a time as
twelve hours.

A smaller species than the last is _B. rostrata_--at the outside 33 feet in
length. Here the hairy covering is reduced[237] to "two small hairs on the
integument covering the apex of the lower maxilla." The colour is greyish
black above, the underside white. On the other hand, _B. sibbaldii_, the
Blue Whale, is the giant of its race, reaching a length of 85 feet. Its
colour is a dark bluish grey, with small whitish spots on the breast. The
dorsal fin is small and low with straight margins.

_B. musculus_, the Finner, is intermediate in size--not more than 70 feet.
It seems doubtful whether the "sulphur bottom," _B. australis_, of
Antarctica and _B. patachonica_ differ specifically from this.[238]

The genus _Megaptera_ is very near _Balaenoptera_, but differs from it
mainly in the following external and internal characters. The dorsal fin is
not very prominent, and its place is taken by a lowish hump, whence,
indeed, the common name of this Whale, "Humpback." The pectoral fin is
unusually long, and the creature uses it to beat itself, the surrounding
water, and, more playfully, its mates. The general outline of this Cetacean
is more clumsy than that of _Balaenoptera_. The most important internal
difference is in the form of the scapula, which has at most a slight
acromion and coracoid process. These are rather more pronounced, according
to Messrs. van Beneden and Gervais,[239] {357} in the southern form of the
genus, which is known as _M. lalandii_. The head, it should also be
remarked, is studded with large tubercles about the size of an orange,
which seem to be hyper-trophied rudiments of the hairs, which should be
present in this region of the body. As is the case with other Whales,
numerous species have been made out of individuals of _Megaptera_. Captain
Scammon, who observed many "gams" or herds of these Whales, remarked[240]
that he had extreme difficulty in finding any two individuals precisely
alike! The best-known species in any case is the northern _M. longimana_,
which occurs on our own coasts. The genus is, like so many Cetaceans,
world-wide in range; and it is possible that the difference in the scapula
already referred to may justify the separation of a southern _M. lalandii_
(with which in that case, perhaps, _M. capensis_ and _M. novae zelandiae_
will be synonymous). Quite recently M. Gervais has insisted upon a
_Megaptera indica_ from the Persian Gulf. _Megaptera_ grows to a length of
50 to 60 feet. Seventy-five feet have been stated, but measurements of
Whales have usually to be received with caution.

_Rhachianectes_, with but one species, _R. glaucus_,[241] the "Californian
Grey Whale," is the last genus of the family Balaenopteridae. This Whale is
but imperfectly known anatomically; but quite sufficient has been
ascertained to show its great divergence from _Balaenoptera_ or
_Megaptera_. The dorsal fin is completely absent, and the throat pleats, so
characteristic of the typical Balaenopteridae, are reduced to two. It has,
however, the general outline of a Rorqual, with a relatively small head. In
osteological characters it tends to unite the two families Balaenopteridae
and Balaenidae (if they are really necessary subdivisions). The skull is on
the whole Rorqual-like; but its fore-part is narrow as in the Greenland
Whale, and the premaxillaries are pinched up in the middle line so as to be
visible from the side; this again is a Balaenid character. The cervical
vertebrae are free as in Rorquals, and the sternum is quite as in that
group. The scapula has more the shape of that of _Balaena_.

_Rhachianectes glaucus_ is confined to the Pacific, and has been
extensively hunted from the shore. It is not, however, a very valuable
Whale, since the baleen is short as in Rorquals, and the {358} beast,
moreover, appears to be fierce, a somewhat rare attribute of Whales. It has
been spoken of, indeed, as "a cunning, courageous, and vicious" animal.
_Rhachianectes_ is essentially a coast Whale, and loves to lie in the surf
in quite shallow water waiting for the tide to float it off. This Whale
varies much in colour from black to mottled grey and black, and reaches a
length of about 40 feet.

FAM. 2. BALAENIDAE.--The Right Whales of the genus _Balaena_ are to be
distinguished from _Neobalaena_ and from the Rorquals by the following
characters:--

The size is large, 50 to 60 feet. There is no dorsal fin. The head is more
than or nearly one-fourth of the entire length of the animal. The baleen is
very long. The throat is not grooved. The orbital process of the frontal is
not wider than the downward process of the maxilla. The cervical vertebrae
are all fused. The scapula is rather high. The hind-limb has the rudiment
of a tibia. The intestine has no caecum.

A vast number of different genera have been founded on detached bones, bits
of whalebone, and more or less complete skeletons of Right Whales coming
from different parts of the world. In Dr. Gray's catalogues we find the
following allowed, viz. _Balaena_, _Eubalaena_, _Hunterius_, _Caperea_,
_Macleayius_. The number of "species" distributed among the genera is some
thirteen or more, with whose names we shall not trouble the reader. As a
matter of fact there are not more than two species which can with certainty
be identified and distinguished, both of which are so close that they
cannot possibly be placed but in the same genus, _Balaena_. In no group of
Whales--in no group of animals probably--has imagination run riot to so
terrible an extent in the formation of genera and species as in these Right
Whales. This multiplication or rather division of genera has arisen from an
old idea that Whales coming from different seas must be of different kinds,
a notion now thoroughly exploded.

The term "Right Whale" simply means that the Whales of this genus are the
right kind of Whale for the whaler to pursue. Their whalebone is longer and
more valuable, while the oil is not only more abundant but of a superior
quality. The two species demand a separate account.

The Greenland Whale, _Balaena mysticetus_, is one of the rare instances of
a Whale which has an exceedingly limited range in {359} space. It is
absolutely confined to the Arctic Ocean, and reported occurrences on our
coasts are due to a confusion with _B. australis_, to be presently
described. At the "Devil's Dyke," near Brighton, there is, or was, the
skull of a most flagrant Rorqual, which is carefully labelled "Greenland
Whale." This Whale grows to a length of 50, 60, rarely 70 feet. It is black
in colour, save for a white patch on the under side of the jaw. The head is
quite one-third of the body in length. There are a few scattered hairs at
the extremity of the jaws. The length of time which this Whale can endure
immersion has been variously stated. The utmost limit of endurance is
stated by Scammon to be one hour and twenty minutes. The pursuit of this
Whale is attended by dangers, not in the least because the animal is itself
fierce and ready to attack, but simply on account of the velocity with
which, and the great depth to which, it will dive, and also to the huge
muscular force which is exerted in its struggles to free itself from the
harpoons. It is indeed an extremely timid beast. It has been remarked that
"a bird alighting upon its back sometimes sets it off in great agitation
and terror." Combined with this timidity of disposition is an intense
affection for its young, "which would do honour," observed Scoresby, "to
the superior intelligence of human beings." Yet that trader and observer
goes on to remark that "the value of the prize ... cannot be sacrificed to
feelings of compassion"! The fact that this Whale and its congener, _B.
australis_, feed among swarms of minute pelagic creatures, which they
engulf in their huge mouths, led the ancients to believe and assert that
they fed upon water only. When the Whale feeds it moves along with some
velocity, taking in huge mouthfuls of sea water with the contained
organisms, which are then strained off by the whalebone and left stranded
upon the tongue.

Unlike its congener, the southern Right Whale, _B. australis_,[242] is
world-wide in distribution, avoiding only the Arctic regions. Where the
Greenland Whale is found _B. australis_ does not exist. The principal
differences which it shows from _B. mysticetus_ are firstly in the
relatively shorter head and shorter and coarser whalebone. In the second
place it has more ribs, fifteen pairs as against thirteen; but there is
apparently some little confusion in the matter of ribs. An additional rib
at the end of the series {360} is apt to get lost, and in the skeleton of
so huge and unmanageable a beast there is nothing more unwise than to
insist upon, as specific characters, what may be due merely to defective
preparation. This Whale has often, and the Greenland Whale also, a rough
horny protuberance upon the snout known as the "bonnet." The causation of
this is not clear. It has been spoken of as "a rudimentary frontal horn."
But this suggestion of an Ungulate affinity can hardly be accepted. It
seems to be more like a kind of corn.

This Whale was once more abundant on the coasts of Europe than it is
to-day; it was much hunted by the Basques in past time. The Whale which
frequented the Bay of Biscay was usually called the Biscayan Whale or _B.
biscayensis_; but there is probably no specific difference. Among the small
towns which fringe the Bay, it is very common to find the Whale
incorporated into the armorial bearings. "Over the portal of the first old
house in the steep street of Guetaria," writes Sir Clements Markham,[243]
"there is a shield of arms consisting of Whales amid waves of the sea. At
Motrico the town arms consist of a Whale in the sea harpooned, and with a
boat with men holding the line." Plenty of other such examples testify to
the prevalence of the whaling industry on these adjoining coasts of Spain
and France. It appears that though the fishery began much earlier--even in
the ninth century--the first actual document relating to it dates from the
year 1150. It is in the shape of privileges granted by Sancho the Wise to
the city of San Sebastian. The trade was still very flourishing in the
sixteenth century. Rondeletius the naturalist described Bayonne as the
centre of the trade, and tells us that the flesh, especially of the tongue,
was exposed for sale as food in the markets.

M. Fischer,[244] who, as well as Sir Clements Markham, has given an
important account of the whaling industry on the Basque shores, quotes an
account of the methods pursued in the sixteenth century. It was at
Biarritz--or as Ambroise Pare, from whom Fischer quotes, spelt it,
Biaris--that the main fisheries were undertaken. The inhabitants set upon a
hill a tower from which they could see "the Balaines which pass, and
perceiving them coming partly by the loud noise they make, and {361} partly
by the water which they throw out by a conduit which they possess in the
middle of the forehead." Several boats then set out in pursuit, some of
which were reserved for men whose sole duty it was to pick out of the water
their comrades who had overbalanced themselves in their excitement. The
harpoons bore a mark by which their respective owners could recognise them,
and the carcase of the animal was shared in accordance with the numbers and
owners of the harpoons found sticking in the dead body of the Whale. At
this period the fishery was at its height. But it continued to be an
occupation along those shores until the beginning of the eighteenth
century, after which it gradually declined. The fishery of Whales began to
be carried farther afield than the shore, and for a long time the Basques
furnished expert harpooners to whaling vessels proceeding to the Arctic
seas. A curious example of the continuance of the fishery until at least
1712 is given by Sir C. Markham. In the parish records of Lequeito for that
year, it is noted that a couple were married who possessed between them all
the necessary outfit for a whaling cruise.

The genus _Neobalaena_ is interesting from more than one point of view. Its
size compared with its gigantic relatives is small, some 16 or 17 feet. The
genus bears the same kind of proportion to _Balaena_ that _Kogia_ does to
_Physeter_ among the Physeteridae. It is one of those Whales which are very
restricted in habitat; up to the present it is only known from the
Antarctic region in the neighbourhood of New Zealand and South Australia.
Structurally it is in a few points intermediate between the Right Whales
and the Rorquals. The head is proportionately (as well as, of course,
actually) not so large as in _Balaena_. There is a falcate dorsal fin; but
the head in outline is not Rorqual-like in spite of its similar
proportions. The whalebone is long. The throat is not grooved. _Neobalaena_
has forty-three vertebrae, of which the cervicals are all fused. There are
as many as seventeen or eighteen dorsal vertebrae, the largest number in
any Cetacean as far as is known. With these are articulated not eighteen
but only seventeen ribs. The first dorsal vertebra appears to be without a
rib. The ribs are very broad and flat. The body thus gets an appearance of
a Sirenian. The lumbar vertebrae are fewer than in any other Cetacean,
being only two. The scapula is more like that of the Rorquals than that of
the Right Whales; {362} that is to say, it is long and not very high. The
skull is most like that of _Balaena_, but the process of the frontal
arching over the eye is broader relatively than in _Balaena_, and thus
approaches _Balaenoptera_. Nothing is known of the viscera of this Whale.
The whalebone is white, and the animal was first described by Dr. Gray from
pieces of "bone." It is not always that so fortunate a diagnosis of
specific or generic difference has been made from a structure which
apparently offers so little aid for discrimination.

There is but a single species of the genus which is named _Neobalaena
marginata_.[245]

SUB-ORDER 2. ODONTOCETI.

The _Odontoceti_ have teeth but no whalebone; the blow-hole is single; the
skull is not symmetrical; some of the ribs are two-headed.

FAM. 1. PHYSETERIDAE.--This family of the Odontocetes may be thus
defined:--All or most of the cervical vertebrae are fused together. The
costal cartilages are not ossified. In the skull the pterygoids are thick
and meet in the middle line; the symphysis of the mandible is long. Teeth,
more or fewer, are found in both jaws, but those of the mandible are alone
functional (? exc. _Kogia_). The pectoral limb is smallish. The throat is
grooved by two or four furrows.

This family of Whales is again susceptible of division into the two
sub-families--Physeterinae or Sperm Whales and the Ziphiinae or Beaked
Whales. Professor P. J. van Beneden was strongly against any subdivision of
what is here regarded as a perfectly natural family, embracing the
Physeters and the Beaked Whales. There are, however, some reasons for the
subdivision. The Ziphiinae have a reduced series of teeth, never exceeding
two on each mandible, which contrasts with the fully-toothed mandibles of
both _Physeter_ and _Kogia_. The stomach of the Ziphioids is
extraordinarily complicated even for a Cetacean. The small head of the
latter group, which recalls in a curious way that of Mosasauroid reptiles
and some Dinosaurs, is in contrast to the {363} enormous head of the
Cachalot and the very fairly-developed skull of the "Pygmy Sperm Whale."
Both, however, furnish spermaceti, and in various osteological details come
near together. On the whole we incline towards separating the Cachalots
from the Ziphioids, and shall therefore commence with the former as being
in some respects the more primitive members of the family Physeteridae.

SUB-FAM. 1. PHYSETERINAE.--This sub-family may be thus defined:--Teeth in
lower jaw numerous. No distinct lachrymal bone. Stomach with only four
compartments (? as to _Kogia_).

Of this sub-family the best-known genus is _Physeter_, including the Sperm
Whale or Cachalot. Of other reputed species we shall speak later. The genus
is characterised in the first place by its large size--as much as 82 feet
of length have been assigned to _Physeter macrocephalus_; but Sir William
Flower thought that 55 or possibly 60 feet might be a better approximation
to the greatest length of the Cachalot. The head is enormous, a third of
the length of the body, and terminates in a massive and bluntish snout.
This is, however, not so abruptly truncated as is often represented in
figures. According to Messrs. Pouchet and Chaves,[246] it slopes forward
two metres beyond the end of the lower jaw; the mouth is thus ventral and
almost shark-like in position, as is the case also with the Pygmy Sperm
Whale, to be considered later. In connexion with this peculiar position of
the mouth, it has been asserted--Mr. F. T. Bullen figures it[247]--that the
Sperm Whale turns over upon its back to bite. The blow-hole is single, and
shaped like the sound-hole of a violin; it lies upon one side, and is not
median in position. The throat is grooved as in the Ziphioids by two
grooves. The dorsal fin is represented by a whole series of lowish humps,
decreasing in elevation from before backwards. The pectoral fins are not
large relatively speaking. The great square head is not occupied entirely
by the skull; the cavity lying above, which is of course traversed by the
tube ending in the blow-hole, is filled with the spermaceti, which is fluid
fat during the life of the animal. Spermaceti also occurs in other Whales;
and that of _Hyperoodon_, whence it has been extracted for commercial
purposes, is said to offer no differences of importance from the spermaceti
of the {364} Sperm Whale. Spermaceti as a drug appears to have been first
mentioned in the pharmacopoeias of the famous medical school of Salerno
towards the year 1100. But it was confounded with a totally distinct
substance, viz. ambergris. The confusion was also made by the famous
alchemist Albertus Magnus, and by the observant Archbishop of Upsala, Olaus
Magnus, in his work _De gentibus septentrionalibus_. It was supposed in
fact by these writers to be the liberated sperm of the Whale, hence
obviously the name. Later on, the substance in question was regarded as the
brain of the Cachalot, in fact as late as the middle of the eighteenth
century. It was Hunter and Camper who really discovered the true nature of
the substance, oil of course, in the cavities of the skull.[248] The huge
skull of _Physeter_ "is perhaps the most modified from the ordinary type"
of skull in the whole mammalian class.

The top of the skull rises into a huge crest lying transversely, and from
it slope forward two lateral crests formed from the maxillary bones; in
this great basin lies the spermaceti already referred to. The skull, as in
Toothed Whales generally, is exceedingly asymmetrical. The right
premaxillary and the left nasal bones are much larger than their fellows;
indeed the right nasal is hardly present as a separate bone. The parietal
if present is fused with the supra-occipital. The jugal is large, and is
not divided into two pieces as it is in the Ziphioids. The pterygoids meet
below for a considerable distance, as in many Dolphins, and in the Edentata
among other mammals. The symphysis of the lower jaw is very long, but the
bones do not appear to be ankylosed. The length of the symphysis recalls
that of the Gangetic Dolphin, _Platanista_.

In the vertebral column the atlas alone is free, the remaining cervicals
being fused. There are only eleven dorsal vertebrae, eight lumbars, and
twenty-four caudals. The breastbone of this Whale is a roughly-triangular
bone made up of three pieces. Four cartilaginous sternal ribs are attached
to this bone. The scapula is remarkable for the fact that it is concave on
the outer and convex on the inner surface; otherwise it is quite typically
Cetacean in form. The shortness of the pectoral limb is shown by the
phalangeal formula, which is as follows:--I 1, II 5, III 5, IV 4, V 3.
{365}

One of the reasons for the pursuit of the Sperm Whale is the desire to
obtain that extremely valuable product ambergris. This substance has long
been known; but its true nature was for centuries in dispute. In Dr.
Johnson's _Dictionary_ (so recently as the edition of 1818!) ambergris is
provided with alternative definitions; it is either the excrement of birds
washed off rocks, or honeycombs that have fallen into the sea!

An old writer asserted of ambergris that it was "not the scum or excrement
of the whale, but issues out of the root of a tree, which tree, howsoever
it stands on the land, alwaies shoots forth its roots towards the sea,
seaking the warmth of it, thereby to deliver the fattest gum that coms out
of it, which tree otherwise by its copious fatness might be burnt and
destroyed." These "explanations" were caused by the fact that ambergris is
sometimes found floating in the sea. Ambergris is, of course, a product of
the intestinal canal of the Sperm Whale; it seems to be of the nature of
cholesterin, and its place of origin was conclusively proved by finding the
beaks of cuttle-fish imbedded in it. When first extracted from the
alimentary canal it is of greasy feel and consistency; later it hardens,
and acquires its characteristic sweet earthy odour. Ambergris is used
mainly as a vehicle for scents, and is a costly substance. A piece weighing
130 lbs. was valued at £500. Though now entirely used in connexion with
perfumery, it was held by the ancients to be of great value as a specific
in certain diseases.

The Sperm Whale is chiefly a tropical animal. Examples that have been cast
up on our shores are strayed individuals. It often goes about in herds,
which seem to be composed of females. Its food is chiefly cuttle-fishes,
and it is said to have a predilection for those colossal cuttle-fishes
whose existence has until recently been doubted. Mr. Bullen has sketched a
conflict between these two giants of the deep. On the other hand it is said
that its large throat, more than big enough to swallow a man (the Whale is
credited with being that which swallowed Jonah), does not usually admit
fishes larger than Bonitos and Albacores.

The ferocity of the Cachalot has been denied and affirmed. It certainly has
great strength, for it can throw itself completely out of the water.
Captain Scammon thinks that ships which are mysteriously lost at sea, with
no obviously assignable cause, are sometimes the victims of the furious
rushes of a bull {366} Sperm Whale. Marco Polo took much the same view, but
suggested that the Whale did not deliberately attack the ship, but was
deceived by the foam following in its wake into thinking "there is
something to eat afloat, and makes a rush forward, whereby it shall often
stave in some part of the ship."[249]

Sir W. Flower and many others are of opinion that there is but one species
of Cachalot. But many names have been given to supposed other forms. The
genus itself has even been divided, and to a set of vertebrae from the
south Dr. Gray gave the perfectly superfluous name of _Meganeuron kreffti_.
The "High-finned Cachalot" rests mainly upon the suggestions of Sir Robert
Sibbald. It is supposed to have a high dorsal fin, and teeth in the upper
as well as in the lower jaw. Common though it was asserted by its describer
to be, there is not a bone, not a fragment even of a bone, alleged to
belong to _Physeter tursio_ in any museum in the world! It seems premature,
therefore, to include this mysterious creature in any list of Cetacea,
though that was done by no less a naturalist than the late Mr. Thomas Bell.
It is this creature round which most of the stories of ferocity congregate.
It is held to be the monster from which Perseus delivered Andromeda, and
which was about to devour Angelica upon the shore of Brittany. The fact of
the matter is, that the Sperm Whale, like so very many other Whales, is
world-wide in range; and those naturalists who did not believe in so wide a
distribution found themselves obliged, in order to satisfy their own views,
to create new species for those of distant localities. Hence the dozen or
so of synonyms which refer to what is to be called _Physeter
macrocephalus_.

The genus _Kogia_ (sometimes written _Cogia_), the so-called "Pygmy Sperm
Whale," is a southern form of much smaller dimensions than its gigantic
ally just described. _Kogia_ does not exceed 15 feet or so in length. It
differs from _Physeter_ also in the well-marked and falcate dorsal fin, in
its generally delphinoid form, in the short snout, and the more normal (for
a Whale) shape of the blow-hole, which is crescentic.

There are also a number of osteological characters in which the two
Physeterines differ from each other. In _Kogia_ all the cervical vertebrae
are ankylosed together; the skull is short, though equally asymmetrical;
the ribs are as many as twelve or {367} fourteen; the scapula has not the
concave face that it has in _Physeter_. The functional teeth of the lower
jaw seem to be reinforced by two on each side of the upper jaw. Moreover,
the articulation of the ribs with the vertebrae does not show the very
anomalous state of affairs that characterises _Physeter_, where the two
heads of a rib may be upon one vertebra.

While there is no doubt as to the generic distinctness of _Kogia_, there is
again the same difficulty that is met with throughout the whole of the
order in settling into how many species the genus requires dividing.

We can dismiss, as unnecessary, additional generic names (_Euphysetes_,
_Callignathus_), but there do appear to be reasons for allowing two
species, if the accounts of their osteology are to be depended upon. One of
these is _K. breviceps_, with thirteen pairs of ribs, no teeth in the upper
jaw, fourteen or fifteen on each side of the lower jaw, vertebral formula
C 7, D 13, L 9, Ca 25, and phalangeal formula I 2, II 8, III 8, IV 8, V 7.

The other will then be _K. simus_, with fourteen pairs of ribs, two teeth
in the upper jaw, nine in each ramus of the lower jaw, vertebral formula
C 7, D 14, L 5, Ca 24, and phalangeal formula I 2, II 5, III 4, IV 4, V 2.

A Californian species has been called _K. floweri_, whose teeth seem to be
particularly long and recurved. And the New Zealand _K. pottsi_ has been
held to be also a distinct form. There seems to be nothing of special
interest to record about the way of life of these Cetaceans, which are but
imperfectly known.

SUB-FAM. 2. ZIPHIINAE.--Teeth in the lower jaw not more than two on each
side. A distinct lachrymal bone. Stomach with very numerous compartments.

These Whales are all of moderate size, not exceeding 30 feet or so in
length. They have a falcate dorsal fin rather near the end of the body; the
muzzle is prolonged, hence the name often given to them of "Beaked Whales."
The throat is grooved; the blow-hole is single and median, crescentic in
form, with the concavity pointing forwards. A character possibly
differentiating the Ziphioids from other Whales is the fact that the body
ends in a rounded projection between the flukes of the tail. This has at
any rate been noted in _Mesoplodon_, _Ziphius_, and _Hyperoodon_. The
Ziphioid Whales are by no means common; indeed of _Berardius_ but four or
five specimens have ever been {368} met with. Most of them are southern in
range, and the vast stretches of desolate coast which occur in these
regions of the world account possibly for the rarity of their remains.
These Whales have done duty more than once for the "Sea Serpent." Quite
recently an alleged sea serpent turned out to be a couple of _Mesoplodon_
lying head to tail! The head in these Whales is small compared to the body.
The skull is characterised by the strong maxillary crests, enormously
developed in the male _Hyperoodon_. The vertex of the skull too is raised,
forming a pronounced prominence behind the aperture of the nares
(blow-hole); in many forms the rostrum is made of very dense bone, and is
thus relatively abundant in rock strata. The pterygoids meet in the middle
line as in the Cachalot. In addition to the few functional teeth in the
lower jaw there are more numerous but small teeth in the upper jaw. These
are not always to be recognised, as they are not attached to the bone, but
merely imbedded in the gums, so that they come away when the skull is
prepared.

The genus _Berardius_[250] differs from _Mesoplodon_ by its rather more
symmetrical skull, of which the vertex is formed by the nasals. The
mesethmoid is only partly ossified. The teeth are two on each side of the
mandible, with their apices directed forwards. The vertebral formula is
C 7, D 10, L 12, Ca 19.

_B. arnouxi_, from the seas of New Zealand, is the only species of this
genus which is well known. It is 30 or 32 feet in length, and is of a
velvety black colour, with a greyish belly. Instead of lowing like a cow,
this Whale has been described as "bellowing like a bull"! A singular and
somewhat inexplicable fact has been stated of this species. The teeth were
said to be protrusible, and Sir James Hector stated that the teeth were
imbedded "in a tough cartilaginous sac which adheres loosely in the socket
of the jaw, and is moved by a series of muscular bundles that elevate or
depress it." Sir William Flower justly observed that these statements
"accord so little with anything hitherto known in mammalian anatomy that
further observations on the subject are extremely desirable." Like other
Ziphioids, _Berardius_ feeds mainly, if not entirely, upon cuttle-fish, a
prey eminently suited to their almost toothless mouths. It is not known
whether _Berardius_ has the {369} Ziphioid grooves upon the throat. Nothing
is known of the structure of the internal viscera of this Whale. It appears
not to be really limited to the region of New Zealand, as is often stated,
for Malm has lately described a skull (_Berardius vegae_) from Bering's
Straits.[251]

_Mesoplodon_[252] is a world-wide genus embracing a number of species; on
the lowest estimate seven species can be distinguished, and Sir W. Flower
would add two more. These are moderate-sized Whales, 15 to 17 feet in
length. In the skull the mesethmoid is ossified; the nasals are sunk
between the upper ends of the premaxillae. There are but a single pair of
teeth in the mandible attached to nearly the middle of its length (whence
the generic name). The vertebral formula is C 7, D 9 or 10, L 10 or 11,
Ca 19 or 20. The sternum consists of four or five pieces. The amount to
which the cervical vertebrae are fused varies; but some are always fused.

The only species which has ever been stranded on the shores of this country
is _M. bidens_, an example of which was described many years ago as the
"Toothless Whale of Havre"; it was an old animal which had probably lost
its teeth. Nevertheless it received the separate generic and specific name
of _Aodon dalei_. The animal lived for two days out of the water, and made
a sound like the "lowing of a cow." An instance of the rarity of the Whales
of this genus is afforded by _M. europaeus_, of which only a single skull
is known; this was extracted from a dead body, found floating, about the
year 1840. It has never appeared since. _M. layardi_ is remarkable on
account of the very large size of its strap-shaped teeth; these curve over
the upper jaw in such a way as to prevent the animal from fully opening its
jaws. The case is curiously paralleled by the Sabre-toothed Tiger. This
species is antarctic in range. From the opposite extremity of the globe
comes _M. stejnegeri_, again known by but a single skull. It is singular on
account of the large size of the brain case, and is a native of Bering's
Straits. _M. hectori_ has its two teeth situated quite at the extremity of
the mandible, and in this feature approximates to the genus _Berardius_. It
was, indeed, confounded with that genus by one naturalist. {370}

_Ziphius_ is a genus which is also of world-wide range. Here again the
number of species is at present merely a matter of opinion. The prevalent
impression, however, is that but a single species exists, which will
therefore have the name of _Z. cavirostris_. The genus (and for the matter
of that the species too) may be thus characterised in comparison with its
allies. The mesethmoid is ossified as in _Mesoplodon_, but the nasals
joined together form the vertex of the skull. There are two teeth near the
symphysis of the mandible, besides the usual small and "functionless" teeth
in the upper jaw. The vertebral formula is C 7, D 9 or 10, L 11, Ca 21.

The throat of a _Ziphius_ from New Zealand was described by Messrs. Scott
and Parker[253] as having three grooves on each side. Whether this form is
the same as von Haast's _Z. novae zelandiae_ is a matter of doubt; but the
individual to which his name has been applied was 26 feet long, and had but
a single groove on each side. Even in the external characters of many
Whales many points require clearing up. Our knowledge of _Ziphius_ dates
from the year 1804, when a skull "completely petrified in appearance" was
picked up upon the Mediterranean coast of France, and described by the
great Cuvier. It was forty years before another specimen was found. In the
New Zealand specimen of von Haast already referred to, the body was scored
by numerous lacerations. These wounds may have been due to fights among the
Whales themselves; the forwardly-situated teeth would be capable of
inflicting such wounds. But it has also been stated that the armed suckers
of gigantic cuttle-fish are responsible for these scratches.

_Hyperoodon_ is the most easily-distinguishable genus of Ziphioid Whales.
Its characters are the following:--The skull has enormously-developed
maxillary crests in the adult male; the mesethmoid is not fully ossified.
There is but a single tooth to each ramus of the lower jaw, besides, of
course, the usual small teeth in the upper jaw. The vertebral formula is
C 7, D 9, L 9, Ca 18. The cervicals are fused into one mass, more or fewer
being free in other Ziphioids. The sternum consists of three pieces only,
the last of which is bifid posteriorly.

The name _Hyperoodon_ was given to this Whale by Colonel Lacepède on
account of the rough papillae upon the palate, which {371} were mistaken by
that observer for teeth. It is curious that the name is really appropriate
in spite of this mistake, though of course it would be so to all the
Ziphioids. In more than one feature this genus comes nearest of all the
Ziphiinae to _Physeter_. Its enormous maxillary crests are paralleled in
that Whale; but in _Hyperoodon_ their great thickness contrasts with the
thinness of those of the Cachalot. The correspondence in the attachment of
a rib to its vertebra by both heads is noteworthy. It is remarkable that in
this particular _Hyperoodon_ is more like _Physeter_ than the supposed
nearest ally of the latter--_Kogia_.

Of this genus two species are known. The best known is the common northern
_H. rostratum_ (with many aliases); the second species from the southern
hemisphere, _H. planifrons_, is only known from a single water- and
pebble-worn skull. Its identification, however, depends upon the known
accuracy of the late Sir William Flower.

The northern species (_Hyperoodon rostratum_) has often been recorded upon
our own coasts; the first record of the stranding of this Whale was in the
year 1717. In that year an example was found at Maldon, in Essex. Like the
Beluga, _Hyperoodon rostratum_ gets lighter in colour with advancing years.
The young are black; the old animals pale brown with some white about them.
The under surface, however, is always greyish white. The length of this
Whale reaches to at any rate 30 feet. But John Hunter had a specimen which
he believed to be 40 feet in length. The specimen, however, consisted only
of a skull, so that error might have crept in. It has already been
mentioned that the old males have enormous maxillary crests. According to
M. Bouvier, who has lately made an exhaustive examination of the anatomy of
this Whale,[254] the females occasionally exhibit the same crests, which
are thus presumably of the nature of spurs sometimes seen in old females
among the Gallinaceous birds. The number of grooves upon the throat is in
dispute in this Whale as in _Ziphius_. One pair is the usual allowance; but
Kükenthal found four in some embryos studied by him. Attention has already
been called to the voice of Ziphioid Whales. _Hyperoodon_ neither "lows"
nor "bellows," but "sobs"! _Hyperoodon rostratum_ is a gregarious Whale,
going about in herds, or "gams" as they should technically be termed, of
four to ten or even fifteen. This Whale {372} can leap right out of the
water, and while in the air can turn its head from side to side, a
capability which has not been mentioned in any other Whale. It can also
stay under water for an unusually long period. Captain Gray,[255] who has
made an accurate study of this species, states that so long a period as two
hours is the limit of endurance; this event occurred in the case of a
harpooned Whale.

FAM. 2. DELPHINIDAE.--This family, which includes the greater number of
Cetacea, may thus be characterised:--Whales of small to moderate size.
Teeth as a rule numerous, and present in the upper as well as in the lower
jaw. Maxillae without large crests; the pterygoids, often meeting in the
middle line, enclose an air space open behind. The anterior (five to eight)
ribs are two headed, the posterior with tubercular head only. The sternal
ribs are ossified.

The Dolphins and Porpoises, as already stated, embrace the greater number
of existing species of Whales. Sir W. Flower and others who have followed
him, allow nineteen genera. But as to the exact number of known species
there is much uncertainty. That very careful observer, Mr. True,
considers[256] that there are fifty which demand recognition. As many as
one hundred have received names. The matter is one which is perhaps barely
ripe for decision. All the Dolphin tribe are, for Whales, smallish animals.
The Killer Whale, _Orca_, is the only genus (or species?) which usually
attains to more than moderate bulk. The rather mysterious _Delphinus
coronatus_, 36 feet in length, of M. de Fréminville, would seem to be a
Ziphioid; it was described as having a very pointed beak, and as having the
dorsal fin situated near the tail; such characters suggest a _Mesoplodon_.

The genus _Delphinapterus_, the Beluga or White Whale, consists of but a
single species, though as usual more than one name has been given to
supposed different species. It is characterised as a genus by the following
assemblage of structural features:--It has only eight to ten teeth
occupying the anterior part of the jaws only. All the cervical vertebrae
are free and unjoined. The vertebral formula is C 7, D 11 (or 12), L 9,
Ca 23. The pterygoids are wide apart, though they converge as if about to
meet at their posterior ends. There is no dorsal fin. The colour is white.
{373}

The Beluga is a northern species purely. The reputed form, _D. kingii_, was
said to come from Australian seas; but there seems to have been an error in
this statement. It is interesting to note that the white colour, so
characteristic of the genus and species, is not found in the young, which
are blackish. They gradually pale as they advance towards maturity.
_Delphinapterus leucas_ reaches a length of 10 feet, and like other
Porpoises will ascend rivers in search of food. It is said to be specially
addicted to salmon. Among the contents of the stomach have been found
quantities of sand. But this habit of swallowing sand or pebbles has been
noted in other Whales. Whether it is or is not accidental (taken in with
ground-living food), it seems hardly likely that it is used for purposes of
ballast! The Beluga has a voice; but the name "Sea Canary" is hardly
suitable to it. A specimen of this species, recently described from the
shores of Scotland (it is often thrown up upon our coasts), which had got
entangled in the stakes of a new net, was regarded by the natives, on
account of its white colour, as a ghost. Externally, besides its colour,
the Beluga is remarkable for possessing a distinct neck, which is
correlated of course with the freedom of the cervical vertebrae, and is
also seen in Platanistidae.

The Narwhal (_Monodon_) is closely allied in structure to the last genus.
It has the following anatomical characters:--The teeth are reduced to a
single "horn" in the upper jaw, which is rudimentary in the female. The
neck vertebrae are free. The vertebral formula is C 7, D 11, L 6, Ca 26.
The pterygoids are as in _Delphinapterus_, and, as in that genus, there are
no hairs upon the face or dorsal fin.

This genus is of course most obviously characterised by the twisted tusk of
the male, which is occasionally double. This tusk has given to the only
species of the genus, _M. monoceros_, both its generic and specific name.
The animal has a spotted colour; but, as in the case of the Beluga, old
animals tend to become white. The use of its horn to _Monodon_ has been
debated. In the first place it is clearly a secondary sexual character. The
males have been observed to cross their horns like rapiers in a fencing
match. It may be that they are used in more serious combats. An ingenious
suggestion is that the long and strong tusk enables its possessor to break
the thick ice and {374} make a breathing hole. A third suggestion is due to
Scoresby, who was led to make it from having taken out of the stomach of a
Narwhal a large skate. He held that with its tusk the Whale empaled the
fish and then swallowed it. The Narwhal is not large, 15 feet or so in
length. But Lacepède, who was apt to compile with lack of discrimination,
speaks of 60 feet long Narwhals. _Monodon_ is purely Arctic, and but three
or four specimens have ever been cast up on our shores.

Of true Porpoises, genus _Phocaena_, there are apparently several species.
The genus itself has the following characters:--The teeth are sixteen to
twenty-six on each half of each jaw; their crowns are compressed and lobed.
The pterygoids do not meet. The dorsal fin has a row of tubercles along its
margin.

The Porpoise of our coasts, _P. communis_, is a smallish species 6 to 8
feet in length. There are two to four hairs present in the young; its
colour is black, generally lighter on the belly. The first six cervical
vertebrae are fused. The ribs vary in number from twelve to fourteen pairs.
It is a gregarious Whale, and will ascend rivers; it has been seen for
example in the Seine at Paris. The name Porpoise is often written
Porkpisce, which of course shows its origin. Very conveniently it was
regarded as a fish, and therefore allowed to be eaten in Lent. The
celebrated Dr. Caius, a gourmet as well as a physician and the refounder of
a college, invented a particular sauce wherewith to dress this royal dish.
Some time since Dr. Gray described a Porpoise from Margate as a distinct
species (see p. 342) on account of the tubercles, which are now known to be
a generic character.

Dr. Burmeister's _P. spinipennis_ seems, however, to be really distinct. It
was captured near the mouth of the Rio de la Plata. It is more tuberculated
on the fin and back, and has fewer teeth (sixteen as against twenty-six).

Mr. True's _P. dallii_ of the Pacific (where the Common Porpoise also
occurs) is characterised chiefly by its very long vertebral column,
consisting of ninety-eight vertebrae; there are only sixty-eight in the
other species. The Eastern genus _Neomeris_ is placed with _Phocaena_ by
Dr. Blanford. It practically only differs by the absence of a dorsal fin.
It is only about 4 feet long, and inhabits the seas of India, Cape of Good
Hope, and Japan. The one species is called _N. phocaenoides_.

The genus _Globicephalus_ is to be defined thus:--Teeth {375} seven to
twelve on each side, confined to anterior end of jaws. Skull raised into a
prominence behind the blow-hole; pterygoids large and in contact. Pectoral
fin long and falcate; dorsal fin present. No beak. Vertebral formula C 7,
D 11, L 11 to 14, Ca 27 to 29. Six pairs of the ribs are two-headed.

The best known species of the genus is the Ca'ing Whale, _G. melas_.[257]
This animal reaches a length of 20 feet, and is thus one of the largest of
the Delphinidae. It is gregarious and was, even is now, much hunted in the
Faeroe Islands. Its sheep-like habits (embodied in one scientific name
_deductor_) enable it to be easily driven on shore in herds, which are then
harpooned. The foetus of this Whale has a few hairs; the number of
phalanges in the two middle digits is very great, as many as eleven to
fourteen. _G. scammoni_, _G. brachypterus_, and _G. indicus_ are other
reputed species of the genus allowed by True and Blanford.

_Grampus_ is a genus allied to the last. It has no teeth in the upper jaw,
and but three to seven in the lower jaw, near the symphysis of the
mandible. The pterygoids are in contact. There is no beak, and the pectoral
fin is long. There are twelve pairs of ribs, of which six are two-headed.
Apparently there is but one species, _G. griseus_, known as "Risso's
Dolphin." It is a Mediterranean and Atlantic form, and is not common.

The genus _Orca_ has as characters:--Teeth ten to thirteen, long and
strong. Pterygoids not quite meeting. Vertebrae C 7, D 11 to 12, L 10,
Ca 23. The first two or three fused. The dorsal fin is long and pointed.

Of this genus there may be more than one species; but the best known is the
Killer Whale, _O. gladiator_ (Fig. 180, p. 341), often spoken of as the
"Grampus."[258] It is marked with contrasting bands of white or yellow upon
a black body-colour. The animal grows to a considerable length, as much as
30 feet. _Orca_ is a powerful and rapacious Whale; and Eschricht has stated
that from the stomach of one, thirteen Porpoises and fourteen Seals were
extracted. They will also combine to attack larger Whales, and Scammon has
related how he witnessed such an onslaught upon a Californian {376} Grey
Whale. "Belua truculenta dentibus," observed Olaus Magnus of this Cetacean.
The high dorsal fin has been much exaggerated in old drawings; it has been
even represented as strong and sharpened at the end, so as to be capable of
ripping open the belly of a Whale. The fact that it sometimes lies over a
little to one side is responsible for another anecdote: that an example of
this Whale was seen to retire with a couple of Seals tucked away under the
flippers, another grasped by the dorsal fin, and a fourth in the mouth!
"When an Orca pursues a whale," wrote Dr. Frangius, "the latter makes a
terrible bellowing like a bull when bitten by a dog." It is probable,
according to F. Cuvier, that this Whale is the "Aries marinus" of the
ancients, certain bands of white upon the head giving an impression of
curved horns. It may also be the "horrible Sea-satyre" of Edmund Spencer.

Allied to _Orca_, but distinguishable from it by some rather minute
peculiarities, is _Pseudorca_. It may be thus defined:--Teeth eight to ten,
much like those of _Orca_. Dorsal fin rather small, falcate. Vertebral
formula C 7, D 10, L 9, Ca 24. Six or all the cervicals united. The curious
fact about this Whale, which embraces only a single species, _P.
crassidens_, is that it was first known in the fossil condition from
remains discovered in the fens of Lincolnshire. An important day for
cetologists was that on which a whole herd entered the Baltic and furnished
material for a better study of this Whale. It is not, any more than its
near ally _Orca_, confined to northern seas; for several examples, at first
relegated to a distinct species (_P. meridionalis_), have been obtained
from the seas round Tasmania.

_Orcella_ (which has been written _Orcaella_) has fourteen to nineteen
small sharp teeth in each half of each jaw. The pterygoids are widely
separate. The dorsal fin is small and falcate. The vertebral formula is
C 7, D 14, L 14, Ca 26. Seven ribs are two-headed, and five of them reach
the sternum.

This genus contains but a single species, _O. brevirostris_, which is both
marine and fresh-water in habit; it occurs in the Indian seas, and in the
Irrawaddy even as far up as 900 miles from the sea. Some regard the
fresh-water individuals as a distinct form, _O. fluminalis_.

_Sagmatias_ is a genus known only from a skull, which is remarkable for the
elevation of the premaxillae into a crest; the {377} pterygoids are short,
and there are thirty-two teeth in each half of each jaw.

_Feresia_ is known from two skulls which are provided with ten to twelve
teeth in each half of each jaw. It is intermediate between _Globicephalus_,
_Grampus_, and _Lagenorhynchus_, according to Sir W. Flower.

The genus _Delphinus_ contains the Dolphin, _D. delphis_.[259] The genus
may be characterised as follows:--Teeth small and numerous, forty-seven to
sixty-five. Vertebral formula C 7, D 14 or 15, L 21 or 22, Ca 30 to 32. The
atlas and axis are fused, the rest free. The palatal border of the maxillae
is deeply grooved. The fins are falcate; the beak long and distinct.

The Common Dolphin of the Mediterranean shows so many variations of colour,
slight differences in the proportions of the bones of the skull, and in the
number of the teeth, that it has been divided up into at least seventeen
"species." But M. Fischer, who has studied many of these forms, does not
admit them, and most students of this group of mammals follow him in the
matter. The Dolphin is and has been the most familiar of Cetaceans; in
consequence it has accumulated much anecdote of a mythical character. The
extreme intelligence and goodwill towards man assigned to this creature by
the ancients are possibly due to the anomaly of a creature ostensibly a
fish showing many of the characters of higher animals. Its unfishlike
intelligence baffled the early observers, who at once endowed it with
especially advanced attributes. Hence the stories of Arion and others. The
leaping of the Dolphin out of the water is exemplified in many
Mediterranean coins and coats of arms; the heraldic dolphin is represented
with an arched back as in leaping. The Dolphin reaches a length of some 7
feet, and appears to be world-wide in range. Possibly distinct is _D.
longirostris_, characterised, as the name denotes, by the very long beak;
it has also more teeth and is a native of Malabar. _D. roseiventris_ again
may be a third species of _Delphinus_. It comes from Torres Straits, and
has the under parts rosy in colour.

The genus _Prodelphinus_ has, like _Delphinus_, a distinct beak; but it has
not the grooved maxillaries. No other character of importance appears to
separate it from _Delphinus_. {378}

The genus consists of some eight widely distributed species, which are none
of them large Dolphins.

_Lagenorhynchus_ has the following assemblage of characters:--Head with
short, not very distinct beak. Dorsal and pectoral fins falcate. Teeth
small, twenty-two to forty-five in each half jaw. Vertebrae ranging in
number from seventy-three to ninety-two. Pterygoid bones either in contact
or separate. There are fifteen or sixteen pairs of ribs, of which six are
two-headed. Of this genus Mr. True allows eight species, which have been
increased by a ninth since the publication of his "Revision."[260]

Two species of _Lagenorhynchus_ are known from our coasts; the rest are
mainly southern in range. The British species are, firstly, _L.
albirostris_, a Dolphin of some 9 feet in length. It has a large number of
vertebrae, ninety-two in number. _L. albirostris_ is a rare species, the
first record of its occurrence on these shores being in 1834. Since that
date some eighteen individuals have been shot or stranded on the shores of
the British Isles. The second British species, _L. acutus_, differs in
colour from the first. As in the last, the upper parts are black and the
under parts white; but in _L. acutus_ there is also a stripe on the flanks,
brownish in colour. It has fewer vertebrae, not more than eighty-two.

The next genus of Dolphins, _Sotalia_, is characterised by--Teeth tolerably
large, twenty-six to thirty-five. The vertebral formula is C 7, D 11 or 12,
L 10 to 14, Ca 22. The pterygoids are not in contact in the middle line. It
has a distinct beak.

Of this genus there are some six species (the exact number, as in so many
other genera, cannot be positively asserted), most of which are fluviatile
or estuarine in habit. They are also on the whole characterised by their
pale, if not actually white, coloration. _S. sinensis_ of the Amoy is white
with pinkish fins. _Sotalia guianensis_ is American as its name denotes. It
is figured by van Beneden as of a pale brown colour. It is very abundant in
the Bay of Rio de Janeiro, and has the reputation of being a friend of man
like some other Dolphins. The natives hold that it will bring to shore the
bodies of drowned persons. The most singular species of the genus is that
recently described by Professor Kükenthal as _S. teüszii_.[261] This animal
is purely fresh-water, being found in {379} the Camaroon river, where it is
extremely rare. The nostrils (blow-hole) are prolonged into a snout-like
process, a fact which is of interest in connexion with the assertion that
in _Balaenoptera_ the blow-hole is puffed out during spouting. What is
temporary in the Rorqual appears to be permanent in the _Sotalia_. More
remarkable still, perhaps, is the assertion that it is a vegetable-feeding
Dolphin. This is not a mere assertion except that it may not apply
universally; for in the stomach of a specimen nothing but vegetable débris
was found. But in the stomachs of other Whales (e.g. _Rhachianectes_)
vegetable matter has also been found, which may perhaps have been taken in
accidentally with the food.

_Steno_ comes near _Sotalia_, and Dr. Blanford has transferred to it (under
the one name of _Steno perniger_) the two species, _Sotalia gadamu_ and
_Sotalia lentiginosa_. It is, however, to be distinguished from _Sotalia_
by the following characters:--Teeth large and few, twenty to twenty-seven
on each side of each jaw, with furrowed surfaces to crowns. Vertebrae C 7,
D 12 or 13, L 15, Ca 30 to 32. Pterygoids in contact. There are but two
species apparently (not counting Dr. Blanford's).

_Tursiops_ is not a very easily definable genus. These are its chief
features:--Teeth large, twenty-two to twenty-six in number in each half of
each jaw. Vertebral formula C 7, D 12 or 13, L 16 or 17, Ca 27. Pterygoids
in contact. Beak distinct. Some five species are allowed; but it seems to
be difficult to differentiate the others from _Tursiops tursio_. This, the
best-known form, is quite or nearly world-wide in range, and occurs, though
not abundantly, on our own coasts. Mr. True has observed that the eyelids
of this Whale, which is largely hunted on the American coast, are as mobile
as those of a terrestrial mammal. The name "tursio" is derived from Pliny.
Belon would also derive from this word the French vernacular "marsouin."
The latter term is sometimes regarded as a corruption of "Meerschwein," but
it would seem to be more probably derivable from "marinum suem," from the
Latin direct. _T. tursio_ has the back black to lead-colour; the under
parts white. In the reputed species, _T. abusalam_, from the Red Sea, the
back is a dark sea-green. _T. tursio_ reaches a length of 12 feet, but is
more usually smaller.

The genus _Tursio_ must be carefully distinguished from {380} _Tursiops_.
It has no dorsal fin, the teeth are small and numerous (forty-four), and
the pterygoids are separate. There are two species, _T. borealis_ and _T.
peronii_, the former being northern and the latter more widely spread.

The genus _Cephalorhynchus_ has for its chief characters the
following:--Teeth twenty-five to thirty-one, small and sharp. Pterygoids
widely separated. Dorsal fin not falcate, but triangular or ovate in form.
Beak not well marked off from the head. The species of this genus are all
southern in range; four are perhaps to be allowed.

FAM. 3. PLATANISTIDAE.--This family of Odontocetes may be distinguished
from the Dolphins by the following assemblage of structural
features:--Cervical vertebrae all free, and each one of some length (for a
Cetacean). Jaws long and narrow, with a considerable length of symphysis.
Teeth very numerous.

This very meagre series of differential characters is largely due to
_Pontoporia_ on the Platanistid side, and to _Monodon_ and _Delphinapterus_
upon the Delphinid side. Otherwise the family Platanistidae would be
extremely distinct. The two last-named genera have separate cervical
vertebrae, and in the Beluga at any rate this is expressed externally by a
quite distinct neck. Moreover, as Mr. True has pointed out, the pterygoid
bones have not the involuted cavity below which characterises other
Dolphins; and they have, what other Dolphins have not, an articulation
outwards with the roofing bones of the skull. Sir W. Flower described the
fact that in Inia (and the same occurs in Pontoporia) the palatines are
separated from each other by the intervention of the vomer. In this feature
they resemble certain Ziphioids, _Berardius_, _Oulodon_ (= _Mesoplodon_)
_grayi_, and _Hyperoodon_. The true Dolphins also appear to show the same
intervention of the vomer in a few cases. There is nothing, therefore,
distinctive from the Delphinidae in this feature.

The existence of cartilaginous sternal ribs in _Inia_ and _Platanista_
shows affinity between these two genera and the Physeteridae. _Pontoporia_
is Dolphin-like in this particular, as it is also in the mode of
articulation of the ribs with the vertebral column. But this last matter
has already been dealt with. The principal reason for placing _Pontoporia_
with the other two genera is the close resemblance which its skull bears to
that of _Inia_.

The first genus of this family which will be noticed is _Platanista_. {381}
The following are its main characters:--Dorsal fin absent. Eyes
rudimentary. Pectoral fins large and truncated at the extremity. Teeth,
about twenty-nine in each half of each jaw. Scapula with the acromion
coinciding with its anterior edge. Skull with enormous maxillary crests,
and with the palatines entirely concealed by the pterygoids. The length of
the above definition will serve to indicate how anomalous in many
particulars is the structure of this "Dolphin."

There is apparently but one species, _P. gangetica_, the "Susu." The Indian
vernacular name is derived from the sound that the animal makes when
spouting. It is an inhabitant of the Ganges and the Indus, together with
their tributaries, and ascends very high up its streams. It is also thought
to be purely fluviatile and never to desert the rivers for the sea.
_Platanista_ lives chiefly by grubbing in the mud for prawns and fish.
Grains of rice have also been found in the stomach, but this would seem to
be accidental. The long snout of the Susu has been compared to the long
snout of the Gharial, a native of the same region. This Whale grows to a
length of over 9 feet, but this length is exceptional. Its anatomy has been
elaborately described by Dr. Anderson.[262]

The next genus, _Inia_, is thus to be characterised:--Dorsal fin
rudimentary; pectorals large and ovate. Teeth, as many as thirty-two on
each side, often with an additional tubercle. Skull without large maxillary
crests; palatines not hidden by pterygoids, but divided by vomer. The
vertebrae of this genus are few in number, only forty-one in all, which are
thus distributed: C 7, D 13, L 3, Ca 18. The peculiarities of the vertebral
column are several. In the first place, as has been mentioned in the
definition of the family, all the cervicals are separate and individually
of some length. Secondly, the axis has a better trace of an odontoid
process than in any other Whale except _Platanista_, where it is even more
obvious. The lumbar region is remarkable on account of its restriction to
three vertebrae. The sternum, by what we must regard as convergence, is
somewhat like that of the Whalebone whales. It consists of one piece only,
of a roughly-oval form, to which apparently only two pairs of
(cartilaginous) sternal ribs are attached. In the fore-limb the proportions
between the humerus and the radius are more like {382} those of terrestrial
mammals; _i.e._ the humerus is distinctly the longer, the converse usually
obtaining among Whales. But _Platanista_ again agrees with _Inia_. The
teeth are remarkable for the fact that the hindermost ones of the series
have an additional lobe; they are not purely conical as are those of Whales
generally.

There is but one species, _Inia geoffrensis_, which inhabits the Amazons,
and grows to a length of 8 feet. Its colour variations are rather
extraordinary, unless they can be set down to sex, which has been denied.
Some individuals are wholly pink; others are black above and pink beneath.
This Whale is believed by the Indians to attack a man in the water, and it
is added that the _Sotalia_ of the same streams will defend him from these
attacks! Naturally, therefore, superstitious reverence attaches to this
Dolphin, which is tiresome to the naturalist who wants specimens, as
Professor Louis Agassiz found.

In the genus _Pontoporia_[263] the dorsal fin is well developed and
falcate. The teeth are very numerous, 200 in all. The ribs articulate as in
Dolphins. The skull closely resembles that of Inia, and the scapula is, as
in that genus, "normal."

The proper name for _Pontoporia_ is really _Stenodelphis_, which name was
first used by Gervais a month or two before Gray, who separated it from the
vague _Delphinus_ of its original discoverer, Gervais himself. It has a
longer snout than _Inia_, which, being bent towards the extremity in a
downward direction, curiously suggests the skull of a Curlew. In details,
however, the skull is exceedingly like that of _Inia_. It is nearly
symmetrical. The vertebral formula appears to be the following:--C 7, D 10,
L 5, Ca 20 = 42, just one over the number of the vertebrae in _Inia_. The
sternum is in two pieces. Of the ten pairs of ribs the first three are
double-headed. These and the next have sternal moieties joining the
sternum, of which the first three are ossified, the last being apparently
merely a ligament.

There is a single species of the genus, _P. blainvillii_. This Whale is
described by Mr. Lydekker as being of a clear brown colour, harmonising
with the waters of the estuary of the Amazons and the La Plata which it
inhabits. The same colour characterises _Sotalia pallida_ of those parts of
the world, and {383} may be a colour adaptation. But the extant accounts of
the colour of this Dolphin vary--quite possibly in accordance with real
variations, such as are exhibited by _Inia_ already spoken of. _Pontoporia
blainvillii_ is a smallish Dolphin some 4 feet in length.

FOSSIL ODONTOCETES.--Several of the existing genera of Dolphins are also
known in a fossil condition, as well as Ziphioid Whales closely related to
existing forms. We shall deal here only with a few genera of fossil
Odontocetes which depart in their structure from existing forms.

The genus _Physodon_ is Miocene, and has been found in Patagonia. It
appears to be most nearly allied to the Physeteridae, but should probably
form a distinct family. _Physodon_ was not so large as _Physeter_, the
skull measuring only some 10 feet. It thus comes nearer in point of size to
_Kogia_, and it is interesting to note that its relatively-shorter snout is
also suggestive of the dwarf Cachalot. The general outline of the skull is,
however, more like that of _Physeter_, and there is the same deep cavity
for the lodgment of spermaceti. The main feature of interest in the skull
is the presence of teeth in both jaws, and the fact that two or three are
lodged in the premaxillae. This is precisely what is found in the most
ancient Whales, the Zeuglodonts.

Extinct Dolphins, apparently referable to the Platanistidae, are the most
numerous among the earlier forms of Cetaceans, and it is significant that
the earliest known forms of these go back to the Eocene.

The genus _Iniopsis_ of Mr. Lydekker,[264] with one species, _I.
caucasica_, comes from rocks which seem to be of that age. The back part of
the skull of this animal, the only part of the skull known, has the same
squarish excavation of the maxillaries that characterises _Inia_ and
_Pontoporia_. Its lower jaw was slender and possessed numerous teeth.

The long snout and jaws of Platanistids, especially exaggerated in
_Pontoporia_ among living forms, are constantly found in these Tertiary
Platanistids.

_Eurhinodelphis_ had a beak three and a half times the length of the
cranium, whereas in _Pontoporia_ the proportions are as 2:1. The teeth too
were very numerous.

The genus _Argyrocetus_, from Patagonian Tertiary strata, was an animal
about as large as the existing Dolphin. It had the {384} slender rostrum
and numerous teeth of the Platanistids and the squared excavations of the
maxillaries. _Argyrocetus patagonicus_ possessed also archaic characters,
suggesting earlier affinities still. The two condyles of the skull instead
of being closely adpressed to the skull stood out in a way more like that
met with in terrestrial mammals. The nasal bones instead of being
abbreviated rudiments are well developed as in the archaic Zeuglodonts. The
cervical vertebrae of this Whale are all perfectly free from each other and
individually long. The skull is on the whole bilaterally symmetrical; this
again is a feature more pronounced among the Platanistidae than among other
Odontocetes. Accompanying these generalised Cetacean characters are some
which show that the animal was too specialised to be the direct ancestor of
any existing forms. The end of the mandible was upturned and without teeth,
its form being quite unique among Cetacea. Other allied forms, such as
_Zarrhachis_ and _Priscodelphinus_, showed the same length of the cervical
vertebrae.

A very distinct family of extinct Whales is that of the SQUALODONTIDAE.
They to some extent bridge over the gap between the existing Odontoceti and
the Eocene Archaeoceti (Zeuglodonts).

The skull of these Whales was on the whole Dolphin-like. But they possessed
teeth which were distinctly specialised into incisors, canines, and molars.
The molars have a coarsely-serrated cutting edge as in the Zeuglodonts, and
are also to some extent two-rooted. But they are more numerous, and so far
approximate to the conditions which characterise the more typical modern
Odontocetes. _Squalodon_ was a long-beaked form, and _Prosqualodon_ had a
skull whose proportions are nearer those of _Kogia_.

SUB-ORDER 3. ARCHAEOCETI.

This division of the Whale tribe embraces but a single family,
ZEUGLODONTIDAE, of which but a single genus, _Zeuglodon_, can with
certainty be discriminated.

_Zeuglodon_ is an Eocene form of large size, with teeth which are limited
in number and disposed in three series as incisors, canines, and molars.
The molars are double-rooted, a fact which has given to the genus its name.
The nasal bones being long {385} instead of rudimentary like those of other
Whales, the blow-hole lies more in the middle of the face. The skull, too,
is not Whale-like in a number of other points. Thus the premaxillaries take
their fair share in the outline of the upper jaw; and, furthermore, bear
the incisor teeth. The parietals meet above in a crest and are not excluded
from the roof of the skull. The vertebrae of the neck are in no way
shortened; neither are they fused together. The ribs are double-headed, and
the sternum is made up of several pieces. Some naturalists, particularly
Professor D'Arcy Thompson,[265] have assigned a relationship to the Seals
to these ancient Cetacea; but others[266] have disputed this view chiefly
on the grounds that the characters which appear to be Seal-like are simply
characters which are generalised and so far at most not Whale-like. Thus
the long neck and the serrated character of the teeth may be accepted as
Seal-like on the one hand; but on the other, a simple serrated tooth and a
long neck are not by any means features of organisation which we should
consider out of the way in an ancient form of Cetacean which probably
preyed upon fish. The humerus of _Zeuglodon_, according to Mr. Lydekker,
puts out of court any possible near relationship to the Seals. But the
matter under dispute can be further studied by reference to the three
memoirs quoted below.

       *       *       *       *       *


{386}

CHAPTER XIII

CARNIVORA[267]--FISSIPEDIA

ORDER VII. CARNIVORA

This order may be thus defined:--Small to large quadrupeds, terrestrial,
arboreal, or aquatic, of usually carnivorous habits. The teeth have
generally sharp and cutting edges, and the canines are well developed; the
incisors are small, and four to six in number. The number of toes is never
less than four. There are usually strong and sharp claws. The clavicles are
incomplete or absent. In the hand the scaphoid and lunar bones are always
united. The brain is well developed, and the hemispheres are well
convoluted. The stomach is always simple, while the caecum, if present, is
always small. The members of this group have a deciduate and zonary
placenta.

The fewness of the characters used in the above definition is chiefly owing
to the fact that the Seals and Sea-lions, although they are referable
without a doubt to this order, have undergone in their metamorphosis into
aquatic animals so many changes that some of the main features in the
structure of their terrestrial relatives have been lost. This group will,
however, be again characterised. We shall deal at present with the land
division of the Carnivora, the CARNIVORA FISSIPEDIA as they are generally
termed. The name is of course given to them to distinguish them from the
corresponding division of the PINNIPEDIA. In the latter group the feet and
hands are modified into "fins"; in the other the fingers and toes are
cleft, as with terrestrial beasts generally. {387}

SUB-ORDER 1. FISSIPEDIA.

[Illustration]

FIG. 190.--Under surface of the cranium of a Dog. × ½. _apf_, Anterior
palatine foramen; _AS_, alisphenoid; _as_, posterior opening of alisphenoid
canal; _BO_, basioccipital; _BS_, basisphenoid; _cf_, condylar foramen;
_eam_, external auditory meatus; _ExO_, exoccipital; _flm_, _flp_, foramen
lacerum medium and posterius; _fm_, foramen magnum; _fo_, foramen ovale;
_Fr_, frontal; _fr_, foramen rotundum; _gf_, glenoid fossa; _gp_,
post-glenoid process; _Ma_, malar; _Mx_, maxilla; _oc_, occipital condyle;
_op_, optic foramen; _Per_, mastoid portion of periotic; _pgf_,
post-glenoid foramen; _Pl_, palatine; _PMx_, premaxilla; _pp_, paroccipital
process; _ppf_, posterior palatine foramen; _PS_, presphenoid; _Pt_,
pterygoid; _sf_, sphenoidal fissure or foramen lacerum anterius; _sm_,
stylomastoid foramen; _SO_, supraoccipital; _Sq_, zygomatic process of
squamosal; _Ty_, tympanic bulla; _Vo_, vomer. (From Flower's _Osteology_.)

A very marked feature of the terrestrial Carnivora is to be found in the
structure of the teeth. The incisors are nearly always six, and are
somewhat feebly developed in many cases. The canines are almost invariably
very large strong teeth, and are always present. In some of the extinct
Cats they reached enormous dimensions. The number of cheek teeth is not
always identical; but the last premolar in the upper jaw and the first true
molar in the lower jaw, known as the "carnassial" or "sectorial" teeth,
mark a difference in structure between the anterior and the posterior
crushing teeth; those in front of the carnassial tooth have cutting edges,
and are often merely small, conical teeth; those behind have broader crowns
and are tuberculate; those of simpler forms often trituberculate; those of
others {388} with numerous tubercles. The carnassial tooth is often, but by
no means always, very much larger and especially longer than the rest of
the molar and premolar series. It is less pronounced in some of the
omnivorous Arctoidea. The skull of the Carnivora is longer in the more
primitive types, such as the Canidae, and shorter in the more specialised
Felidae. The orbit is hardly ever completely shut off by bone, though the
postorbital process of the frontal sometimes approaches the corresponding
upward process of the zygomatic arch. The palate, which is completely
ossified, sometimes reaches back for some distance behind the teeth; it
always extends as far as the last molar. The tympanic bulla is often very
inflated, and if flatter, as in the Bears, is at any rate large and
conspicuous. The lower jaw has a high coronoid process, and the condyle is
transversely elongated, this part of the bone being rolled into an almost
cylindrical form; it fits very closely into the glenoid cavity, and the
articulation is thereby very strict--an obvious advantage in a creature
with so great a need for power of jaw.

[Illustration]

FIG. 191.--A, Atlas of Dog. Ventral view, × ½. B, Axis of Dog. Side view, ×
2/3. _o_, Odontoid process; _pz_, posterior zygapophysis; _s_, spinous
process; _sn_, foramen for first spinal nerve; _t_, transverse process;
_v_, vertebrarterial canal. (From Flower's _Osteology_.)

In the vertebral column the atlas always has large wing-like processes; the
spine of the axis vertebra has a long antero-posteriorly elongated form.
The transverse processes of the fourth to the sixth cervicals are, as a
rule, double. These features, however, though characteristic of the
Carnivora are not by any means distinctive. The true sacrum consists of but
a single vertebra to which the ilia are attached; but at most two other
vertebrae are fused with this. The clavicle is always small and sometimes
quite rudimentary, or even absent. The spine of the scapula is well
developed, and almost equally divides the {389} surface of that bone. The
digits of the Carnivora are mostly five, and are never less than four. The
mode of progression may be digitigrade or plantigrade, and the intermediate
semidigitigrade mode of walking also occurs. The brain in all Carnivora is
large and well convoluted. The arrangement of the convolutions is
characteristic. There are three or four gyri disposed round each other, of
which the lowest surrounds the Sylvian fissure. The stomach in these
creatures is always simple in form, without {390} subdivisions. The caecum
is never large, and may be, as in the Bear tribe, completely absent.

[Illustration]

FIG. 192.--Brain of Dog. A, Ventral; B, dorsal; C, lateral aspect. _B.ol_,
Olfactory lobe; _Cr.ce_, crura cerebri; _Fi.p_, great longitudinal fissure;
_HH_, _HH_^1, lateral lobes of cerebellum; _Hyp_, hypophysis; _Med_, spinal
cord; _NH_, medulla oblongata; _Po_, pons Varolii; _VH_, cerebral
hemispheres; _Wu_, middle lobe (vermis) of cerebellum; _I-XII_, cerebral
nerves. (From Wiedersheim's _Comparative Anatomy_.)

The distribution of the Carnivora is world-wide, excluding only the
Australian region, if, as seems probable, the Dingo of that region is an
introduced species. The most striking features in their distribution are
perhaps the following:--There are no Bears in the Ethiopian region or in
Madagascar, and but a single species in the Neotropical. The only Carnivora
in Madagascar are the Viverridae, and of the seven genera there found six
are peculiar. The Procyonidae are nearly entirely New World in range; out
of sixteen genera of Mustelidae only five are New World, and only two of
those are peculiar to the American continent. The Hyaenidae are limited to
the Old World.

The classification of the Carnivora is a matter which is difficult, and
which has therefore been very variously effected. It is unfortunate that
the classification of Flower (based upon the researches of H. N. Turner as
well as his own, and accepted by Mivart) should fail when applied to fossil
forms. For it separates with great clearness the existing genera into three
great divisions, the Cynoidea, Aeluroidea, and Arctoidea, definable by
visceral as well as by osteological characters. The apparent anomaly, too,
of a single supposed Viverrine genus, to wit _Bassariscus_, existing in
America, while all the rest of its kin are Old-World forms, was shown by
his characters to be neither an anomaly nor a fact. It will be better,
therefore, to divide the Carnivora into the families, Felidae,
Machaerodontidae, Viverridae, Hyaenidae, Canidae, Ursidae, Procyonidae, and
Mustelidae, indicating at the same time the reasons for and against
retaining the three divisions of Sir W. Flower.

FAM. 1. FELIDAE.[268]--This family includes only the Cats (_i.e._ Lions,
Tigers, "Cats," Hunting Leopard, etc.), and is to be distinguished by the
following characters:--In the skull the auditory bulla is much inflated,
and there is an internal septum; the paroccipital processes are flattened
against the bullae. There is no alisphenoidal canal. The dental formula is
I 3, C 1, Pm 3 to 2, M 1. The carnassial tooth of the upper jaw has three
lobes to the blade; that of the lower jaw is without an inner cusp. {391}
The digits are five on the fore-feet, four on the hind. The caecum is
present and small. This family contains but two genera, _Felis_ and
_Cynaelurus_.

[Illustration]

FIG. 193.--Section of auditory bulla of Tiger. _am_, Auditory meatus; _BO_,
basioccipital; _e_, Eustachian canal; _ic_, _oc_, two chambers of bulla
divided by _s_, septum; *, their aperture of communication; _Pt_, periotic;
_Sq_, squamosal; _t_, tympanic ring. (From Flower's _Osteology_.)

The genus _Felis_ is very wide in its distribution, being common to both
the Old and the New Worlds. Its distinctive characters, as opposed to
_Cynaelurus_, are mainly the following:--The claws are retractile, and the
retractility is more markedly developed than in the Cheetah. The molar is
not so nearly in a line with the other teeth; the upper carnassial,
moreover, has an inner tubercle. The legs are relatively shorter.

The complete retractility of the claws is a very distinctive feature of the
true Cats. It is brought about in this way: the terminal joint of the toe,
which is clad with the claw, folds back into a sheath by the outer side of
or above the middle phalanx. It is held in this position by a strong
ligament. The flexor muscles straighten the phalanx which bears the claw,
so that the natural position for the animal is to be in a state of
retracted claws, which of course preserves them from friction; when wanted
for aggressive purposes, they are pulled into sight by the action of the
muscles already mentioned.

[Illustration]

FIG. 194.--The phalanges of the middle digit of the manus of the Lion
(_Felis leo_). × ½. _a_, The central portion forming the internal support
to the horny claw; _b_, the bony lamina reflected around the base of the
claw; _ph_^1, proximal phalanx; _ph_^2, middle phalanx; _ph_^3, ungual
phalanx. (From Flower's _Osteology_.)

Much has been written as to the shape of the pupil of the Cat's eye. Some
careful observations upon the matter have been {392} made by Dr. Lindsay
Johnson,[269] who found that out of 180 Domestic Cats 111 had round pupils,
and that in 19 the shape was a pointed oval, intermediate conditions being
offered by the rest. These 180 comprised males and females of many
varieties. When the pupil of the Cat's eye contracts, it forms a vertical
slit with two pin holes, one at each end, through which alone light appears
to enter. In the Genet and the Civet the contraction of the pupil is as in
the Cat. In the Lion, Tiger--in fact apparently in all the large Cats--the
pupil retains its circular shape even when contraction is fully effected.
Dr. Johnson has, furthermore,[270] made some interesting experiments upon
the Seal's eye--a creature which has, of course, to exert its powers of
vision in two media, and from one to the other. This is effected by
dilatation of the pupil when in the water, and its contraction to a
vertical slit with parallel margins and rounded ends when in the air, the
contraction being to some extent at least under the influence of the
animal's will.

The coloration of these creatures is very varied: spots of black, or
bordered with black upon a more or less tawny ground-colour, is the
prevailing pattern. Stripes are also met with, as in the Tiger, but these
are usually cross stripes,[271] while in the related Viverridae there are
many examples of longitudinal stripes. Finally, many Cats, as for instance
the Puma and the Eyra, are "self-coloured"--have, that is to say, a uniform
tint. Just as the unstriped Horse sometimes shows traces of the former
existence of stripes, so the self-coloured Cats are occasionally spotted
when young; this is markedly so in the case of the Puma; while the Lion is
spotted as a cub, and in the adult--particularly in the lioness--there are
distinct indications of these spots. It is evident, therefore, that there
are grounds for regarding a spotted condition to be antecedent, at least in
some cases, to a uniform colour. There are divers explanations of these
hues and of these changes. It is held by many that the coloration has a
relation to the habits of the creature: the spotted Cats, it is pointed
out, are largely arboreal; this is eminently so with the Jaguar at any
rate; and in an arboreal {393} creature the spots, it is said, give the
impression of flecks of sunlight broken up by foliage. On the other hand,
the self-coloured Cats of a sandy to earthen hue assimilate in tint with a
sandy or stony soil. The stripes of the Tiger, it is thought, approximate
to the tall parallel stems of grasses and other plants in the dense cover
in which it lives. In favour of these views is undoubtedly the fact that in
other mammals and other animals belonging to quite different groups the
same four plans of coloration are met with. Spots and cross stripes are
found in the Marsupials; the young Tapir is spotted while the adult is
self-coloured, and so forth. This last fact, however, serves to illustrate
another view which has been put forward in explanation of these
characteristic markings of the Felidae. Eimer has come to the conclusion
that there is and has been a regular series of steps in the evolution of
these markings. The primitive condition was, he thinks, a longitudinally
striped one; the stripes then broke up into spots, and the spots rearranged
themselves as transverse stripes; the self-coloured Puma and Lion are a
final stage in this gradual evolution. In support of this is the fact that
spots precede self-coloration in the individual growth of these animals.
The exact sequence of these markings is, however, contradicted by Dr.
Haacke's observations upon a certain Australian fish which is cross striped
when young and longitudinally striped when adult, a precise reversal of
what ought to occur on Eimer's view.

The Felidae are almost universally distributed with the exception, of
course, of Australia and a good deal of the Australian region; the
headquarters of the group are undoubtedly in the tropics of the Old World.

The characteristics of a few species of the Cat tribe will now be given. As
there are at any rate forty-five species, this survey will have to be
somewhat incomplete.

The Lion, _F. leo_, differs from all other species by the mane of the male.
It is an inhabitant of Africa, India, and certain parts of Western Asia.
Within the historic period it ranged into Europe. According to Sir Samuel
Baker those of us who have not seen the Lion in his native haunts have
never seen a really magnificent specimen of the brute; but other travellers
disagree, and state that a captive Lion is often a finer animal--by reason,
of course, of good feeding. Unlike the majority of Cats, the Lion {394}
cannot climb. His roar (which is so suggestive, towards its end, of that
animal who once dressed himself up in his skin) is literally _after_ his
prey. The Lion, it is stated, does not roar except upon a full stomach. The
Lion is mainly nocturnal in its habits, and is said to be not in the least
dangerous if unprovoked in the daytime; but here again opinions differ. The
tail of the animal is provided at the extremity with a slight claw, but it
can hardly be sufficient for the animal to lash itself into a fury with it.
A Lion will live for thirty or forty years, and will breed freely in
captivity. The Gardens of the Zoological Society of Dublin have been famed
for their success in breeding Lions; but more surprising still, this has
been successfully accomplished in travelling menageries. The "desert"
colour of the Lion is familiar to all. It is stated that the likeness to
the parched soil of certain parts of Africa is greatly heightened by black
patches in the mane, for in certain regions of that continent the arid
yellow of the general environment is diversified by pieces of black lava.
It is apparently a popular delusion to speak of the Maneless Lion of
Guzerat. No doubt maneless Lions do come from there, but so do young and
maneless Lions from other places; in short, it is simply a question of age,
and old Lions from the Asiatic continent are as fully maned as those from
Africa.

The Tiger, _F. tigris_, is an animal of about the same size as the Lion,
distinguished, of course, by the stripes. The skeletons are much like those
of other Cats; but the skull of the Tiger may be distinguished from that of
the Lion by the fact that the nasal bones reach back beyond the frontal
processes of the maxillae. The Tiger is an exclusively Asiatic beast,
ranging northward into icy Siberia. The northern individuals have a closer
fur, and have been quite unnecessarily separated as a distinct variety.
Nine feet six inches is the size of the average full-grown Tiger; but the
skins will stretch, a fact of which the sportsman will sometimes take
advantage. A "man-eater" is a Tiger which has discovered "that it is far
easier to kill a native than to hunt for the scarce jungle game." As with
the Lion, the accounts of travellers differ enormously, particularly with
regard to the strength of the creature. Some have said that a Tiger can
easily lift a full-grown bullock and leap with it in the mouth over a
considerable obstacle, a statement which is ridiculed by Sir Samuel Baker.
Unlike the Lion, the Tiger can climb trees; {395} it will also voluntarily
enter the water, and can swim considerable rivers.

Mr. H. N. Ridley[272] observes that Tigers "habitually swim over to
Singapore across the Johore Strait, usually by way of the intermediate
islands of Pulau Ubin and Pulau Tekong. They make the passage at night,
landing in the early morning. As so much of the coast is mangrove swamp,
and the animals do not risk going through the mud, they are only able to
cross where the shores are sandy, and thus they have regular starting- and
landing-places."

The Tiger is mainly nocturnal, but begins its depredations towards five
o'clock in the afternoon, before which it remains sleeping in shady
thickets. If the weather is rainy and windy it becomes restless and wanders
about earlier. Under the provocation of extreme hunger it will hunt during
the daytime. Hunger, too, naturally produces extreme boldness. Mr. Ridley
relates a story of four Tigers who walked up the steps of a house in search
of the master of the house or his dog, and broke into it, the inhabitants
retiring in their favour. The Malays have superstitions about Tigers, which
are precisely paralleled by the man-and-wolf stories of Europe. "Certain
people are supposed to have the power of turning into tigers for a short
time, and resuming their human form at pleasure. The transformation
commences tail first, and the human tiger is so completely changed that not
only has it all the actions and appearance of the tiger, but on resuming
its human form it is quite unconscious of what it has been doing in the
tiger state." Mr. Ridley disputes the common stories as to man-eaters. If a
Tiger has once tasted human flesh it does not always confine itself
afterwards to that article of diet, nor is it only aged and comparatively
toothless animals which hunt man. That they do take a large toll of coolies
is an undoubted fact, and many are the artifices to prevent the rest from
knowing the fate of one of their fellow-workmen, or of becoming acquainted
with the presence in the neighbourhood of one of the dreaded beasts.

The Leopard or Panther, _F. pardus_, is, like the Lion, African and Asiatic
in range. The animal is spotted with rosettes of black spots surrounding a
central field of the tawny colour of the body generally. Some of the spots
are solid and black. "The {396} pantere like unto the smaragdyne" seems to
be an inapt description of this Cat, unless indeed the eyes be referred to.
The ancients ascribed to it a most fragrant odour. As with the Tiger, a
northern variety of this Carnivore has a closer and longer fur. There is a
tendency towards melanism in this animal, the black Leopard being
comparatively common, particularly, it appears, in high lands. Several
other variations in colour are known. These have received different
specific names; but it seems that there is in reality but one species of
Leopard. The Leopard can climb with the agility of any Cat. Sir S. Baker
reserves the name Panther for large Leopards, which reach a length of 7
feet 6 inches. But there is no valid distinction between any two such
varieties. The Leopard is as ferocious as the Tiger; and Sir Samuel Baker
advises that the power of the human eye be not experimented with when
meeting unarmed one of these brutes.

[Illustration]

FIG. 195.--Snow Leopard. _Felis uncia._ × 1/20.

The Snow Leopard or Ounce, _F. uncia_, is a beautiful creature, confined to
the highlands of Central Asia. The ground-colour is white, and the spots
are larger than those of the ordinary Leopard. Two examples of this rather
rare Carnivore have been recently on view in the Zoological Society's
Gardens, London. The Clouded Leopard, _F. nebulosa_, is an animal of
considerable size (6 feet total length). {397}

The Fishing Cat, _F. viverrina_, of India and China, is about 3 feet 6
inches including the tail. Its black spots upon a grey-brown ground have a
tendency to form longitudinal lines. It is in fact, on Eimer's theory, a
case of longitudinal stripes breaking up into spots. It differs from the
bulk of Cats by preying upon fish, though it is not known how it catches
them. It also feeds upon the large snail _Ampullaria_. In addition to these
there are twenty-four species of Cats found in the Old World, mainly in the
Oriental region, of small to moderate size.

[Illustration]

FIG. 196.--European Lynx. _Felis lynx._ × 1/12.

The European Lynx, _F. lynx_, has rather long legs, a short tail, and
tufted, pointed ears. It has only two premolars in the upper jaw instead of
the usual three. It seems to be doubtful whether the Asiatic Lynx can be
distinguished from the European, but the Spanish form, _F. pardina_, does
appear to be distinct. The Common Lynx, sometimes called _F. canadensis_,
also ranges into America, where some other forms exist, known by the
specific names of _F. rufa_ and _F. baileyi_.

In America there are altogether sixteen species of Cats, if we allow three
species of Lynx, none of which, however, does Dr. Mivart allow to be
different from the European and Asiatic Lynx (_F. lynx_). {398}

The largest of American Cats is the Jaguar, _F. onca_. This is an arboreal
creature with a long, heavy body and short limbs. Its pelage is much like
that of the Leopard, but the spots are larger and more definitely arranged
in groups. There are a number of distinct rows of spots. The length of the
body alone is not greater than 4 feet. They prey very largely on the
Capybara, and upon turtles, which they surprise upon the sand when about to
lay their eggs; the reptiles are turned upon their backs, so as to be
incapable of escaping, and the Jaguar then easily devours them. The Jaguar
will even pursue the turtle into the water, and will devour its eggs and
the newly-hatched young.

[Illustration]

FIG. 197.--Jaguar. _Felis onca._ × 1/15.

The Ocelot is another spotted American Cat. _F. pardalis_[273] ranges from
Arkansas in North America southwards, its range corresponding with that of
the Jaguar. Although small for one of the "larger cats," the Ocelot
inspired with considerable respect Captain Dampier, who remarked of it:
"The Tigre-cat is about the bigness of a bull-dog, with short truss, body
shaped much like a mastiff, but in all things else, its head, the colour of
its hair, the manner of its preying, much resembling the {399} tigre, only
somewhat less.... But I have wisht them farther off when I have met them in
the woods; because their aspect appears so very stately and fierce."

[Illustration]

FIG. 198.--Ocelot. _Felis pardalis._ × 1/10.

The Puma, _F. concolor_, the American Lion as it is called in the north, is
a rather smaller animal than the last, and of a uniform tawny colour,
tending to white on the abdomen and to a dark stripe along the back. The
young, as already mentioned, are very distinctly spotted. Like the Tiger,
the Puma can endure extremes of heat and cold; it is equally at home in the
snow of North America and among the tropical forests and swamps of the
south. It is a ferocious creature so far as concerns Deer, Lamas, Raccoons,
even Skunks and Rheas, but, according to Mr. W. H. Hudson, will not attack
man, and will even defend him against the Jaguar.[274] In captivity the
Puma will purr like a Cat.

The Eyra, _F. eyra_, is another self-coloured American cat, which has a
curious likeness to the totally distinct _Cryptoprocta_ of Madagascar.

The Wild Cat of Europe, _F. catus_, is found over the greater part of
Europe, and also in Northern Asia. It was undoubtedly common at one time in
this country, though it appears never to have extended its range into
Ireland. But the real Wild Cat is now rare in this island, and is confined
to certain districts in {400} Scotland. Plenty of alleged wild Cats have
been seen and even shot; but these are too frequently merely feral Cats,
_i.e._ domestic tabbies which have reverted to a hunting life. The real
Wild Cat differs from the domestic races by the proportionately longer body
and limbs, the shorter and thicker tail; the pads of the toes are not quite
black. The period of the gestation of the Wild Cat, according to Mr. Cocks,
is a week or so longer than that of any domestic Cat.

The Domestic Cat is in fact regarded as the descendant of the Eastern _F.
caffra_, or (perhaps _and_) the closely-allied _F. maniculata_. It is
highly probable, however, that after introduction into this country as a
domestic animal it has interbred with the Wild Cat. Many allied species of
Cats will interbreed, even two so far apart as the Lion and the Tiger.
There are interesting archaeological and linguistic reasons for regarding
the Domestic Cat as an importation. The legend of Dick Whittington's Cat
points to it being a rare and valuable animal, which a tamed _F. catus_
would not at that time have been. There was an enactment in Wales of a
penalty against him who should kill the king's Cat, again suggestive of its
rarity and consequent value. The very name "Puss" is a hint of a foreign
origin. Some would derive it from Perse, and upon this is based the notion
that the Cat is from Persia. But it seems that Puss is the same as Pasht
and Bubastis, showing so far an Egyptian origin for the animal. The
ancestral Cats mentioned above are natives of Egypt.[275]

The genus _Cynaelurus_, which includes but a single species, _C. jubatus_,
the Cheetah or Hunting Leopard, is separated from _Felis_ by a number of
characters. In the first place the claws are non-retractile, or at least
less retractile than those of the true Cats. It is, moreover, longer
legged. The molar is more in a line with the other teeth of the jaw, and
the upper carnassial tooth has no inner tubercle. Messrs. Windle and
Parsons have lately pointed out many Dog-like features in the muscles. This
animal is about as large as a Leopard, but has plain black spots. As its
vernacular name implies it is used for sport, and is quite easily tameable.
It will purr like the Puma. The Cheetah occurs in India, Persia, Turkestan,
and also in Africa; the latter {401} form is sometimes, though quite
unnecessarily, separated as _C. lanigera_. The genus occurs fossil in the
Siwalik deposits of India, the species being known as _C. brachygnatha_.

FAM. 2. MACHAERODONTIDAE.--This is a family of totally-extinct Cats which
range from the Eocene down to the Pleistocene. Their general structure is
like that of the Felidae; but they differ in a number of skeletal features.
Thus there is an alisphenoid canal, and, as in Bears, there is a
postglenoid foramen. There is also a distinct carotid foramen, which does
not occur in the true Cats. The teeth are often distinguished by the huge
size of the superior canines, which are "weapons for penetrating wounds,
without rival among carnivorous animals." These must have been displayed at
the sides of the chin when the mouth was closed, and it has even been
suggested that the animal possessing these exaggerated canines could hardly
have properly closed its mouth. The lower canines were often on the
contrary much reduced, and in fact incisor-like. In tracing the series of
these Cats we find a gradual reduction of the teeth from a more nearly
complete number down to the specialised dentition of the existing Cats. The
genus _Proaelurus_, Miocene in range, had four premolars in each jaw, and
two molars in the lower and one in the upper. This is the greatest number
of teeth found in any member of the group.

The resemblance of this genus to _Cryptoprocta_ has been insisted upon.
_Archaelurus_ has suffered a reduction, since one premolar in the lower jaw
has disappeared, its formula being thus I 3/3 C 1/1 Pm 4/3 M 1/2. The next
stage is shown by _Dinictis_ with three premolars in both jaws. There are a
good many species of this genus which are all American and Miocene. This
genus has five toes upon the hind-feet, and was probably plantigrade. It
had retractile claws.

In the genus _Nimravus_ the dental formula is still further reduced.
Another premolar of the lower jaw has gone, the formula being thus I 3/3
C 1/1 Pm 3/2 M 1/2. _Nimravus gomphodus_ was a Carnivore about the size of
a Panther. It has no third trochanter upon the femur, which process is
present in the corresponding bone of _Dinictis_. _Pogonodon_ was an equally
large animal in which the premolars were three in each jaw, but the molars
have become reduced to one in the lower, as they have in this and other
genera in the upper {402} jaw. Finally, _Hoplophoneus_ has acquired the
dentition of existing Cats.

The Machaerodons, however, show examples with a yet more reduced dentition
than that of the most reduced existing Cat, viz. the Lynx, which has only
two premolars in each jaw and one molar. In _Eusmilus_ the molar in both
jaws is single, and there is but one premolar in the lower jaw.

The genus _Machaerodus_ itself, which appears to include _Smilodon_, is
referred by Cope to the true Cats, and not to the Nimravidae, as he terms
the family which we have called here the Machaerodontidae. These creatures
are known as "Sabre-toothed Tigers," and were of very wide distribution,
occurring in South America as well as in Europe and North America. "As
nothing," remarks Professor Cope, "but the characters of the canine teeth
distinguished these from typical felines, it is to these that we must look
for the cause of their failure to continue. Professor Flower's suggestion
appears to be a good one, viz. that the length of these teeth became an
inconvenience and a hindrance to their possessors. I think there can be no
doubt that the huge canines in the Smilodons must have prevented the biting
off of flesh from large pieces, so as to greatly interfere with feeding,
and to keep the animals in poor condition. The size of the canines is such
as to prevent their use as cutting instruments excepting with the mouth
closed; for the latter could not have been opened sufficiently to allow any
object to enter it from the front. Even when it opens so far as to allow
the mandible to pass behind the apices of the canines, there would appear
to be some risk of the latter being caught on the point of one or the other
canine, and forced to remain open, causing early starvation. Such may have
been the fate of the fine individual of the _S. neogaeus_, Lund, whose
skull was found in Brazil by Lund, and which is familiar to us through the
figures of de Blainville."

_Machaerodus_ is placed among the Felidae on account of the fact that the
condyloid and carotid foramina unite with the foramen lacerum posterius.
But as in at least one species, _M. palmidens_, there is an alisphenoid
canal, which, however, has disappeared in the more recent American forms,
it seems permissible to retain the genus in the family Machaerodontidae
though its existence reduces the differential character of that family to a
minimum. The genus goes back to the Eocene. {403}

FAM. 3. VIVERRIDAE.--The Civets, Genets, and their kind differ from the
Cats in a number of points. They form, however, by no means so uniform an
assemblage as do the Cats; so that the difficulty is, as Dr. Mivart has
remarked, not to divide them into sub-families, but to avoid making too
many. But before proceeding to subdivide the family we shall describe the
characters of the family and contrast them with those of the Felidae.

All the Viverridae are comparatively small creatures. The head and body are
more elongate than in the Cats. The fingers and toes are generally five;
but there are some (e.g. _Cynictis_) where the formula of the toes is as in
the Cats, _i.e._ four on the hind-foot. In the Suricate the fingers are
also reduced to four. The claws are perhaps never completely
retractile,[276] and often are not at all so. The dental formulae of the
genera differ considerably; but in the majority there are more teeth than
in the Felidae. The well-known sharp-pointed, conical papillae of the Cat's
tongue are not present. The majority have a scent gland beneath the tail,
from which the perfume civet is derived. There are a number of osteological
characters which differentiate the two families; thus the alisphenoid canal
is sometimes present. The bulla is divided, as in the Cats, but is
externally constricted.

It seems clear from some at any rate of the characters, _i.e._ the more
complete dentition, the five-fingered hands and feet, the non-retractile
claws, etc., that the Civets are on a lower level of specialisation than
are the Cats.

SUB-FAM. 1. EUPLERINAE.--The genus _Eupleres_ is in many ways the most
aberrant type of Viverrid, and is placed in a sub-family, Euplerinae. Its
salient feature is the very peculiar dentition: peculiar in the small size
of the canines, the canine-like character of the anterior premolars, and
the resemblance of the premolars to molars. In some of the characters of
the teeth, _Eupleres_ is Insectivore-like, and was formerly grouped with
that family. There are four premolars and two molars in each jaw on each
side. It has five toes upon both fore- and hind-limbs; the skull is very
slender. It has no alisphenoid canal. The only species, _E. goudotii_, is
of an olive-grey colour, with dark bands across the shoulders in the young.
The nose and upper lip are grooved. There are no scent glands. It appears
to burrow in the ground, and possibly contents itself with a diet of worms.
_Eupleres_ is a {404} native of Madagascar, where all the most peculiar
Viverridae live.

SUB-FAM. 2. GALIDICTIINAE.--Mivart has placed in this sub-family the three
Mascarene genera, _Galidia_, _Hemigalidia_, and _Galidictis_. In them the
orbit is not enclosed by bone; there is no alisphenoid canal, and there are
five toes and fingers.

_Galidia_ consists of but one species, _G. elegans_, of a chestnut brown
colour, with a tail ringed with black. The claws are not retractile. The
scent gland is absent. There are five digits upon both hand and foot. There
are three premolars and two molars on each side of each jaw. The caecum is
(for an Aeluroid) long, and pointed at the apex; it is quite twice the
length of that of _Genetta_.

Closely allied to _Galidia_ is the genus _Hemigalidia_, of which there are
two species. It is distinguished from the last genus by the non-annulated
tail. It also differs in the dental formula, which is for the molars Pm 4/3
M 2/1. This animal is termed by Buffon the Vansire. He correctly enumerates
its grinders, and distinguishes it from the Ferret!

_Galidictis_ is a third genus from Madagascar containing two species, one
of which has been unfortunately named _G. vittata_, leading perhaps to some
confusion with the totally distinct _Galictis vittata_. As in the last two
genera the digits are five. The dental formula is that of _Galidia_. It is
distinguished from the other two genera of its sub-family by the
longitudinal brown striping of the upper part of the greyish body.

SUB-FAM. 3. CRYPTOPROCTINAE.--_Cryptoprocta_[277] represents a special
sub-family, Cryptoproctinae, and includes only a single species, the Fossa
(_C. ferox_) of Madagascar. It is the largest Carnivore of Madagascar,
being about twice the size of a Cat, but with an elongated body; the colour
is a tawny brown with no striping. The animal is active and lithe in its
motions, and is said to be of almost unexampled ferocity in disposition.
Its exact systematic position has been much discussed. By Zittel it is
placed in a sub-family (including the extinct _Proaelurus_ and
_Pseudaelurus_) of the Felidae. Mivart and Lydekker, on the other hand,
regard it as a genus of the Viverridae. The dental formula of the molars,
Pm 3/3 M 1/1, is {405} more like that of the _Felidae_ than of the
_Viverridae_, and the teeth are more Feline in structure. The claws of the
feet are retractile. As to internal structure the Fossa agrees largely with
the Viverridae, but then this family has no very marked points of
difference from the Felidae; but where the anatomy does diverge from that
of the Felidae it approaches the Viverridae, especially in the muscular
system.

[Illustration]

FIG. 199.--Fossa. _Cryptoprocta ferox._ × 1/6.

The remaining and by far the larger number of genera of Civets are grouped
by Professor Mivart in two sub-families: the VIVERRINAE, including the
genera _Viverra_, _Viverricula_, _Fossa_, _Genetta_, _Prionodon_, _Poiana_,
_Paradoxurus_, _Arctogale_, _Hemigale_, _Arctictis_, _Nandinia_, and
_Cynogale_; and the HERPESTINAE, including the genera _Herpestes_,
_Helogale_, _Cynictis_, and probably _Bdeogale_ and _Rhynchogale_. In the
Viverrinae the digits are always five, the claws are more or less
retractile, the prescrotal scent glands are usually present, and the anus
does not open into a sac. On the other hand, the Herpestinae are
characterised by the non-retractility of the claws, the absence of the
glands in question, and the fact that the anus does open into a terminal
sac.

SUB-FAM. 4. VIVERRINAE.--_Viverra_ includes the true Civets. The genus,
save for one African species, is Oriental in range. The molar formula is
the complete one for the Viverridae, viz. {406} Pm 4/4 M 2/2. The secretion
of the prescrotal gland of _V. civetta_ yields the civet of commerce.

The "Rasse," genus _Viverricula_, has been separated generically from the
true Civets. It is, remarkably enough, common to both Madagascar[278] and
many parts of the Oriental region. It is, moreover, capable of climbing
trees, which its relatives are not. It has no mane like _Viverra_ and is of
slighter build.

[Illustration]

FIG. 200.--Civet Cat. _Viverra civetta._ × 1/6.

_Prionodon_ or _Linsang_ differs from the last two genera in the loss of an
upper molar. It thus approaches the Cats, with which it also agrees in the
furry feet. It is a purely Oriental genus. It also resembles the Cats in
that the claws are apparently quite retractile, a feature not common among
the group. There are three species of the genus. _P. pardicolor_ has large
black spots and a ringed tail. Its body is some 15 inches in length. Dr.
Mivart has commented upon the particularly small caecum, which, like that
of _Arctictis_, seems to be on the verge of disappearance.

_Genetta_, including the Genets, is almost purely African. It has the full
tooth formula of _Viverra_; but is to be distinguished by the absence of a
scent pouch, and by a naked strip of skin running up the metatarsus. These
animals are all brownish yellowish to greyish with darker spots. The Common
Genet, _G. vulgaris_, is South European, and just gets into Asia; it is
also North African. The Genet, an animal "with an appetite for petty
carnage," is one of those smaller Carnivora which are possibly to be
regarded as meant by the word [Greek: galê], and appear to have
"functioned" as Cats among the Greeks. So recently as {407} the times of
Belon we are told (by him) that Genets were common and tame at
Constantinople.

_Poiana_, containing a single African species, a spotted and entirely
Genet-like animal, has been separated as a distinct genus. Dr. Mivart,
however, holds it to be a _Prionodon_ which has acquired a Genet-like
tarsus.

_Arctictis_, containing but one species, _A. binturong_, the Binturong, is
in some ways an exceptional form. It is a black arboreal creature of not
very wide range in the Oriental region, with a fully prehensile tail. This
feature and its plantigrade foot with naked sole have led to its being
regarded as more allied to the Arctoidea. It is, however, undoubtedly an
ally of _Paradoxurus_. The caecum is small, or may be quite absent. The
dentition is I 3/3 C 1/1 Pm 4/3 M 2/2. The structure of the animal has been
investigated by Garrod.[279]

The genus _Fossa_ is a Viverrine confined to Madagascar. There is but one
species, _F. daubentoni_, the "Fossane." It is distinguished from _Viverra_
by the presence of two bare spots on the under surface of the metatarsus in
the hind-limb, and by the absence of a scent pouch. The animal is not much
spotted and striped, but the striping in the young is much more marked.

Of the genus _Paradoxurus_ there are some ten or a dozen species, belonging
entirely to the Oriental region. The teeth are as in _Viverra_, but
occasionally the molars are reduced to one. The pupils are vertical. The
tail though long is not prehensile, "but the animal appears to have the
power of coiling it to some extent, and in caged specimens the coiled
condition not unfrequently becomes confirmed and permanent" (Blanford).
This fact accounts for the name _Paradoxurus_; for a prehensile tail is
hardly to be expected in an animal of the zoological position of the Palm
Civets, and yet its occasional twisting led originally to the view that it
was so. The genus has scent glands. The dentition is I 3/3 C 1/1 Pm 4/4
M 2/2. _P. niger_, the Indian Palm Civet, is, like other species, not often
to be seen in a wild condition. It is arboreal, and, like other members of
the genus, feeds upon a mixed diet, consisting of all kinds of small
Vertebrata and insects, varied by fruit. Another species, _P. grayi_, is so
distinctly vegetarian in its habits that it makes considerable havoc in
pine-apple beds in the Andaman Islands.

{408}

_Arctogale_ is another Oriental genus with very small teeth, those of the
molar series being hardly in contact. The soles of the feet are more naked
than in the last genus, and the scent glands, if present, appear to be
small and ill developed. It has also a long tail, and is arboreal in way of
life. There is "nothing particular recorded" as to its habits. The species
are _A. leucotis_ and _A. stigmatica_.

[Illustration]

FIG. 201.--Hardwicke's Civet Cat. _Hemigale hardwicki._ × 1/5. (From
_Nature_.)

Closely allied to both the last genera is _Hemigale_, also an Oriental
genus. It is to be distinguished from _Paradoxurus_ by having the soles of
the feet much less naked, though they are more so than in _Viverra_ or
_Prionodon_. The coloration of the species, _H. hardwicki_ (a Malayan
animal), is very peculiar. The body is banded with five or six broad
transverse stripes, and the basal portion of the tail is also ringed, an
uncommon feature in the group. A second species of this genus is _H.
hosei_, from Borneo. It is blackish in colour, but is not a melanic variety
of the last.

_Nandinia_ appears never to possess a caecum.[280] It is also peculiar
among Carnivora in the non-ossification of the hinder {409} part of the
bulla. It is an African genus, containing two species which are spotted.
The tail is ringed.

_Cynogale_ is at any rate a partially aquatic, short-tailed, web-footed,
reddish brown-coloured Civet, which lives upon fish and Crustacea, and
inhabits the Malay Peninsula, Sumatra, and Borneo. It has long
"moustaches," and is said to have a head bearing a singular resemblance to
the head of the Insectivorous "Otter" _Potamogale_. The metatarsus is bald,
and the pollex and hallux are very well developed.

SUB-FAM. 5. HERPESTINAE.--There are over twenty species of _Herpestes_
(Mongooses) divided between the Ethiopian and Oriental regions, one
species, _H. ichneumon_, being also found in Europe. The fur has a "pepper
and salt" appearance; the feet are plantigrade. There are five fingers and
toes. The pollex and hallux are small; the tail is long. The tarsus and
metatarsus are usually naked. The Egyptian species "has been injudiciously
denominated the Cat of Pharaoh." It is perhaps better known as Pharaoh's
Mouse. The beast is so far Cat-like that it will destroy Rats and Mice; and
it has been exported to sugar plantations for that very purpose. More
famous are its combats with venomous serpents. According to Aristotle and
Pliny the Ichneumon first coats its body with a coating of mud, in which it
wallows, and then with this armour can defy the serpent. Topsell tells the
tale better. The Ichneumon burrows in the sand, and "when the aspe espyeth
her threatening rage, presently turning about her taile, provoketh the
ichneumon to combate, and with an open mouth and lofty head doth enter the
list, to her owne perdition. For the ichneumon being nothing afraid of this
great bravado, receiveth the encounter, and taking the head of the aspe in
his mouth biteth that off to prevent the casting out of her poison." In the
West Indies the animal has been described as fearlessly attacking the
deadly Fer de Lance and receiving its bites with impunity; it is also added
that it will eat the leaves of a particular plant as an antidote! The real
explanation of the result of these encounters is of course the agility of
the Ichneumon[281]--_fort cauteleuse beste_, as Belon says.

Another species, _H. albicauda_, is distinguished, as the name denotes, by
its white tail. A species of this genus, _H. urva_, {410} sometimes raised
to generic rank as _Urva_, is partly aquatic in habit; it feeds upon crabs
and frogs, but is quite willing to take to poultry and their eggs.

_Helogale_ is a genus whose validity appears doubtful (to Dr. Mivart). It
is African, and contains two species.

[Illustration]

FIG. 202.--White-tailed Ichneumon. _Herpestes albicauda._ × 1/5.

_Cynictis_ is an African genus, with five digits on the fore-limbs and four
on the hind. As in _Herpestes_, the orbit is completely encircled by bone.
There is but a single species, _C. penicillata_, which is of a reddish
colour and has a bushy tail.

_Bdeogale_, also African, has the toes still further reduced; there are
only four on both limbs. The tarsus is hairy and the tail bushy. They are
"very rare animals, and nothing is known of their habits." It is known,
however, that they will kill poisonous snakes, for Dr. Peters took a
Rhinoceros Viper out of the stomach of one.

_Rhynchogale_[282] differs from all other genera of Viverridae, except
_Crossarchus_ and _Suricata_, in having no groove upon the muzzle. There
are five digits. There is the full Viverrine dentition, with five premolars
in the upper jaw; but this may be an abnormality.[283]

_Crossarchus_ differs from the last in only having three premolars on each
side of each jaw. It is also African, and there are several species.

_Suricata_ is the last genus of Viverridae; it is also African, and
contains a single species, _Suricata tetradactyla_, the "Meerkat" of the
Cape. The Suricate has but four toes on each foot; the tarsus and the
metatarsus are naked below. The body is banded posteriorly. There are
fifteen dorsal vertebrae, and the orbit is {411} closed by bone. The
Suricate lives in caves and rock crevices, and will dig burrows. It is
distinctly a diurnal animal, and sits upon its hind-legs after the fashion
of a Marmot. As Buffon noticed in a tame specimen (thought by him to be a
native of Surinam), the animal barks like a dog. The Suricate is largely
vegetarian, living upon roots.

[Illustration]

FIG. 203.--Suricate. _Suricata tetradactyla._ × ¼.

FAM. 4. HYAENIDAE.--Unlike though the Hyaenas appear to be to the last
family--mainly perhaps on account of size--they are, nevertheless, very
nearly akin to them, more so than to the Cat tribe. It will be remembered
that the striping and spotting of the Hyaenas is very Genet- and
Suricate-like.

There are admittedly two genera among the Hyaenidae, _Hyaena_ itself with
three species,[284] and the Aard Wolf, _Proteles_, with but one. But Dr.
Mivart considers that the Spotted Hyaena should form a genus apart,
_Crocuta_--a proceeding which was initiated by the late Dr. Gray of the
British Museum. The Hyaenidae are to be distinguished by the following
characters:--There are generally four toes, always so in the hind-foot. The
claws are non-retractile. The nose and upper lip are grooved. The molar
formula is Pm 4/3 M 1/1. The soles of the feet are covered with hairs upon
the tarsus and metatarsus. No scent glands. Tail short. Dorsal vertebrae
more numerous than in other Aeluroids, _i.e._ fifteen. The bulla is divided
by a rudimentary septum only.

{412}

[Illustration]

FIG. 204.--Spotted Hyaena. _Crocuta maculata._ × 1/12.

The genera _Hyaena_ and _Crocuta_, the Striped and Spotted Hyaena
respectively, are African and Asiatic in range, _Crocuta_ being limited to
South Africa. There is neither hallux nor pollex.

[Illustration]

FIG. 205.--Striped Hyaena. _Hyaena striata._ × 1/12.

The Hyaenas, stigmatised by Sir Samuel Baker as "low-caste creatures," are
mainly carrion feeders. Much Arab superstition is associated with them.
Certain peculiarities in the structure {413} of the organs of reproduction
have led to the belief that a Hyaena changes its sex every year. Its almost
human-sounding howls are supposed to be a deliberate trap for the unwary
traveller. There is also a legend that in the eye of the Hyaena is a stone
which if placed under the tongue of a man endows him with the gift of
prophecy.

_Proteles_ presents many resemblances to the Hyaenas, but also certain
differences; by many it is placed in a separate family. There is but one
species, _P. cristata_, the Aard Wolf of South Africa. In outward aspect it
is very Hyaena-like, the coat being striped, and the ears, though longer,
resembling those of a Hyaena. There is also a mane. There are, however,
five toes on the fore-feet. The teeth are feebler, particularly the molars,
which are also reduced in number. The skull, as in _Hyaena_, has no
alisphenoid canal, but the bulla tympani is divided by a septum. The animal
seems to feed largely upon insects, particularly Termites, and also upon
carrion.[285]

Of extinct Hyaenoids _Ictitherium_ seems to be transitional between them
and the Viverridae. Its dentition, 3/3, 1/1, 4/3, 2/1, is that of a
Viverrid, and the feet are five-toed. The upper carnassial tooth, however,
is like that of _Hyaena_ in having a strong inner cusp. Other extinct
genera of Hyaenas are _Lycyaena_ and _Hyaenictis_. The genus _Hyaena_
itself goes back as far as to the Miocene, and occurred in Europe until the
Pleistocene. The Cave Hyaena of this country seems to be indistinguishable
from _Crocuta maculata_, though it has received the name of _H. spelaea_.

FAM. 5. CANIDAE.[286]--This family cannot be divided into more than five
genera, and is universally distributed with the exception of New Zealand.
The auditory bulla is smooth and rounded, and has internally a very
incomplete septum, extending through about one-fourth or one-third of the
cavity. The meatus has a fairly prominent under lip. The paroccipital
process is long and prominent. The mastoid is distinct, though but slightly
developed. The glenoid foramen is large; the condyloid foramen is
conspicuous, and the carotid canal is deep within the foramen lacerum
posterius. The last three characters are Bear-like; the {414} form of the
bulla is Aeluroid. The teeth vary somewhat in number, and the following
table will serve to indicate the gradual reduction observable in the number
of molars:--

  _Otocyon_           I 3/3 C 1/1 Pm 4/4 M (3 or 4)/4
  _Canis_ generally   I 3/3 C 1/1 Pm 4/4 M (3 or 2)/(4 or 3)
  _Cyon_              I 3/3 C 1/1 Pm 4/4 M 2/2
  _Icticyon_          I 3/3 C 1/1 Pm 4/4 M (2 or 1)/2

All the Dogs have a caecum[287] of simple cylindrical form. In _C.
cancrivorus_, _C. jubatus_, and _Nyctereutes procyonides_ this organ is
straight or only very faintly curved; in other Dogs it is coiled into an
[288]-like form, sometimes with an additional twist. The Dogs have, as a
rule, five toes, one being dropped in _Lycaon_. The tail is fairly long and
distinctly bushy. There is in a number of species a gland at the root of
the tail, the presence of which can frequently be detected by the wet
appearance due to the oozing secretion. The great majority of existing
Canidae belong to the genus _Canis_. But certainly three, and more
doubtfully four, other genera can be distinguished.

The genus _Icticyon_ contains but one recent species, the Bush Dog (_I.
venaticus_, Lund) of British Guiana. The animal has a somewhat
Paradoxure-like, at any rate a distinctly un-dog-like, aspect, being
longish in the body (some 2 feet long), shortish in the legs, and
big-headed. It is blackish in colour, verging towards golden brown on the
head and back. Sir W. Flower, to whom we owe our chief knowledge of its
structure, characterises it as like a young Fox, and with the playful
manners of a puppy. The animal appears to hunt in packs and by scent, and
has a reputation for ferocity. _Icticyon_ differs from _Canis_ and agrees
with the Indian _Cuon_ in having but forty teeth, the last molar having
disappeared from the upper and lower jaws. The caecum, unlike that of the
majority of Canidae, is only slightly curved. The brain, oddly enough,
shows a Cat-like peculiarity. It has been pointed out that in their long
bodies and short legs the genera _Cuon_ and _Icticyon_ resemble the
primitive dogs.[289]

A genus _Nyctereutes_ is usually separated from _Canis_ for the inclusion
of _N. procyonides_ only. The separation is based upon {415} the strikingly
unusual coloration of this Dog. It is a small animal, with numerous long
white hairs dorsally. The face, chest, and much of the belly are black. Its
aspect distinctly recalls that of a Raccoon,[290] especially in the black
patches below the eyes, whence of course the scientific name and the
pseudo-vernacular "Raccoon-like Dog." It inhabits China and Japan. As to
structure, there is hardly anything that justifies its exclusion from the
genus _Canis_. Garrod, however, mentions the unusually large size of the
Spigelian lobe of the liver.

[Illustration]

FIG. 206.--Raccoon-like Dog. _Nyctereutes procyonides._ × 1/6.

Wortman and Malkens[291] have instituted a genus _Nothocyon_ for Dr.
Mivart's species _C. urostictus_[292] and _C. parvidens_, which are both
South American forms.

The genus _Otocyon_ contains but one species, _O. megalotis_, an African
species, ranging pretty widely in that continent (from the Cape to
Somaliland, in sandy districts), and sometimes confused with the Fennec on
account of its long ears. Its principal structural difference from other
Dogs is that there is an additional molar in each jaw, the molar formula
being thus M 3/4 or even 4/4. Moreover the carnassial teeth are not so
pronounced, and Professor Huxley laid especial stress upon the {416}
likeness of some of the cheek teeth to those of the more primitive
Arctoids. The angle of the lower jaw is inflected, a character, however,
which seems to be more general than is usually allowed among animals not
referable to the Marsupials. It is possible that _Otocyon_ is a persistent
Creodont-like form which has developed in a direction curiously, and in a
most detailed fashion, parallel to the Dogs. If, however, we may assume the
addition of the molar, then this anomalous but not necessarily untenable
conclusion is obviated.

The genus _Cuon_, or _Cyon_, has been instituted for the two or three
species of Eastern Dogs (_C. primaevus_, _C. dukkunensis_, etc.) which
agree with each other in the constant loss of a molar in the lower jaw, or,
it should be said, almost constant loss, for the missing tooth is
occasionally represented. The latter of the two species mentioned, the
Dhole, is, like its congeners, an animal which hunts in packs; it is said
to hunt even the ferocious Tiger, and to be thus one of the few animals
which can face the largest and fiercest of the Carnivora.

The genus _Lycaon_ is a very distinct type, being differentiated from other
Dogs by the possession of only four toes on both fore- and hind-limbs, and
by the dental formula, which is Pm 4/4 M 2/3. The one species is _L.
pictus_, the Cape Hunting Dog. It is singularly like a Hyaena[293] in
general appearance; the ochraceous grey ground-colour with black markings
and the long ears produce this likeness. The animal has got its vernacular
name from the habit of hunting in packs. Its range is over a good part of
Africa. The occurrence of this species (or at least genus, for the name _L.
anglicus_ has been used) in caves in Glamorganshire seems to show that it
is a comparatively recent immigrant into Africa. As to its visceral
structures, _Lycaon_[294] does not differ widely from other Dogs. It has,
however, no lytta beneath the tongue. The intestines are thus divided:
large, 9 feet 1 inch; small, 1 foot 3 inches. This contrasts with the
proportions observable in some other Dogs. While other Dogs have but a
cartilaginous rudiment of the clavicle, _Lycaon_ has a considerably larger
representative of this bone.

[Illustration]

FIG. 207.--Fennec Fox. _Canis zerda._ × 1/5.

[Illustration]

FIG. 208.--Prairie Wolf or Coyote. _Canis latrans._ × 1/8.

The bulk of the Dogs, Wolves, Foxes, and Jackals are thus left over for
inclusion in the genus _Canis_. But the numerous {417} members of this
genus can, according to Professor Huxley, be sorted into two series by
certain cranial characters. The two series he termed the "Alopecoid" or
Fox-like, and the "Thooid" or Wolf-like. It was suggested that the generic
name _Vulpes_ be used for the former, and _Canis_ for the second. The
characters which will be dealt with immediately are also to be noted among
{418} the Dogs belonging to genera that have already been separated off.
Thus _Lycaon_ is distinctly Thooid. The characters in question are
these:--In the Fox series, the frontal air-sinus of the Thooids is absent;
the cranial cavity is pear-shaped, without an abrupt angle coinciding with
the supra-orbital sulcus, such as exists in the other group; the coronoid
process of the mandible is rather higher and more turned back in the Foxes,
while the depth of the mandible at the level of the first molar is greater.

[Illustration]

FIG. 209.--Japanese Wolf. _Canis hodophylax._ × 1/8 (From _Nature_.)

To the Fox series belong among others the species _C. lagopus_ (Arctic
Fox), _C. zerda_ (the Fennec), _C. chama_ (the Silver-backed Fox of
Africa), _C. virginianus_ (the Virginian Fox), _C. velox_ (the Kit Fox),
and of course the Common Fox of this country. On the other hand, the Dogs
proper (such as _C. dingo_), the Wolves (_C. lupus_, _C. pallipes_, _C.
niger_), the Japanese Wolf (_C. hodophylax_), the Red Wolf of America (_C.
jubatus_), the Jackals (_C. aureus_, _C. anthus_, etc.), the Prairie Wolf
(_C. latrans_), and a number of American forms, such as _C. azarae_, its
close ally _C. cancrivorus_ ( = _C. rudis_), _C. antarcticus_, _C.
magellanicus_, etc., are decidedly Wolves rather than Foxes. {419}

The Arctic Fox, _Canis lagopus_, is known by its bluish summer and pure
white winter dress as "Blue Fox" and "White Fox" respectively. It is an
inhabitant of the Arctic north; but in former days, as its remains show, it
descended to such southern latitudes as Germany and this country. The most
southern point which it now inhabits is Iceland. This small Fox is well
known as being one of the few animals which change their dress to a
complete white in winter. This change is, however, not absolutely
universal; and M. Trouessart has even stated that the supposed change does
not exist, but that the colours are a question of age and sex. This Fox
feeds on birds and cast-up carcases of Whales and Seals; it is also said to
devour shell-fish, and actually to store up food when abundant for seasons
of scarcity. A Fox has been observed to "carry off eggs in his mouth from
an eider duck's nest, one at a time, until the whole were removed"; and in
winter to "scratch a hole down through very deep snow to a _cache_ of eggs
beneath." These anecdotes are told by Sir Leopold McClintock; but others
have also asserted the storing habits of this Fox, which really has only a
short time of the year in which it can catch suitable living food.

_Canis vulpes_, the Fox, is not only a native of England, but extends as
far to the east as Egypt, the so-called _C. aegyptiacus_ being at most a
mere variety. Varieties indeed occur in these islands; the English Fox
being redder, the Scotch greyer. Not only is the Fox a truly indigenous
English beast, but its remains go back a very long way into past time. Its
bones occur in the Red Crag, a deposit of Pliocene times. Its prevalence
now is no doubt due to its preservation as a beast of chase. It lives in
burrows, either excavating them itself or taking possession of those of
some other animal; the Badger suffers in this way, and is said to be
vanquished not by the teeth of the burglarious Fox, but by its far fouler
habits! It is curious that the expression "foxing" is not so suitable to
this animal as to many others. The habit of "shamming death" is a
widely-spread one in the animal world, but at least not common with our
Fox. The sagacity of the Fox appears to be a little more proverbial than
actual; literature teems with its accomplishments. The worthy Archbishop of
Upsala, Olaus Magnus, figured Foxes dipping their tails in the streams, and
then pulling out inquisitive crayfishes {420} which had seized upon them.
"It is a crafty, lively, and libidinous creature," observed a writer of the
last century.

Of Jackals there are many species, both African and Oriental. Mr. de Winton
allows the following list of African species[295]:--_C. anthus_, _C.
variegatus_, _C. mesomelas_, _C. lateralis_. _C. mesomelas_ is
distinguished by the broad black patch in the middle of the back. These
animals do not appear to go in packs as so many Canidae do; they live upon
carrion, but also rob hen-roosts, and commit other depredations upon the
live stock of farmers. The "Quaha," _C. lateralis_, is distinguished from
the last by its sharp bark, and by the obvious side stripe which has given
to it its name. It is curious that it should live in apparent amity with
_C. mesomelas_, since the habits of the two are identical and would lead,
one might suppose, to a severe struggle for existence, in which one of the
two would disappear. Of Indian Jackals _C. aureus_ is the most familiar
type.

[Illustration]

FIG. 210.--Wolf. _Canis lupus._ × 1/8.

The European Wolf, _Canis lupus_, was once, but is no longer, an inhabitant
of the British Islands. Their former prevalence is indicated by many names
of towns and villages, such as Ulceby and Usselby in Lincolnshire, the town
of Wolverton, and Woolmer Forest. In Saxon times Wolves were very abundant;
and even so recently as the reign of Elizabeth they were to be seen on
{421} Dartmoor and in the Forest of Dean. In the New Forest they were
hunted in the twelfth century. It would seem that the last English Wolf was
slain some time during the reign of Henry VII. In Scotland, however, they
persisted very much longer. So recently as 1743 was the last killed. But
before this period they had begun to get exceedingly scarce, for the price
of a skin in 1620 is quoted at £6:13:4. In Ireland Wolves lingered yet
longer; about 1770 is believed to be the date of their final extinction in
that island. The Wolf nowadays is distributed over the greater part of
Europe, Northern Asia, and North America, the American form not being
considered to be distinct from its European ally. Much legend has collected
round this fierce Carnivore. Aristotle, usually accurate in the main, still
"states more of wolves than experience warranted." Pliny, unable to sift
truth from falsehood, was in this matter "an eager listener to all old
women's tales." Aelian added to his marvels and asserted that the Wolf
cannot bend its head back; if it should happen to tread on the flower of
the squill it at once becomes torpid. So the wily fox, fearing his more
powerful enemy, takes care to strew his path with squills! The conversion
of men into Wolves was a well-known superstition, dating from Grecian and
Roman times; it formed the basis of much of the witchcraft persecutions of
the Middle Ages and onwards, and has left its mark in folklore, _e.g._ the
Wolf in "Red Riding Hood."

The Indian Wolves, _C. pallipes_, _C. chanco_, and _C. laniger_, are
hardly, if at all, different from _C. lupus_. Professor Huxley has remarked
upon the likeness of _C. pallipes_ to a Jackal, thus bridging over the very
inconsiderable gap that may be held to divide Jackals and Wolves.

The Dingo, _Canis dingo_, is an interesting and somewhat mysterious species
of Dog or Wolf. As is well known, it is an Australian species; but it does
not seem to be certain whether it was tamed and brought over to Australia
by the native races, or is a true and indigenous Australian species.

The colour of this species varies, but is usually of a reddish brown; it
is, however, often grey and indeed almost black. Whether indigenous or
introduced, the Dingo is a plague to Australian settlers, devouring Sheep,
which it generally destroys by tearing out the paunch. It does not as a
rule hunt in packs. The Dingo is stated to feign death with so much
persistence that {422} an individual has been known to be partly flayed
before moving. Dingo remains have been found in river-gravels in Australia
where no human remains have been detected. This argues for its indigeneity;
but, on the other hand, it has been pointed out that man himself in the
Australian continent goes back a very long way into time, and may thus
still have imported this companion with him. Anyhow it is quite a wild
creature now. Dr. Nehring, an expert investigator into the subject of
domestic animals, has stated that the skeleton of the Dingo does not
suggest a feral animal at all but a purely wild race.

[Illustration]

FIG. 211.--Dingo. _Canis dingo._ × 1/8.

The Domestic Dog is usually spoken of as _Canis familiaris_; but to remains
in bone caverns the name of _C. ferus_ or _C. mikii_ has been given. There
seems to be no doubt that the Dog was the "friend of man" in very early
times. Its remains have been met with in Danish kitchen-middens, in the
lake-dwellings of the Swiss lakes, and during the Bronze Age in Europe
generally. But "there are few more vexed questions in the archaeology of
natural history than the origin of the dog." Its remains already referred
to may in many cases have argued its use as food. But in a Neolithic barrow
a Dog was found buried with a woman, the {423} skeletons of both being _in
situ_; this animal was about the size of a Shepherd Dog. The actual Dog of
to-day is divisible into more than 180 different breeds; but in a work upon
"Natural History" it would seem out of place to enumerate and characterise
these artificial products. Authors vary in their opinion as to what stock
gave rise to the domestic races of the past and of to-day. The Jackal, the
Bunasu (_C. primaevus_), the Indian Wolf (_C. pallipes_), have been
proposed as likely ancestors. It is more probable that there is much
admixture, and that various wild types have been selected by man in various
countries.

EXTINCT CANIDAE.--Many of the existing species of Canidae are also to be
found in Pleistocene deposits of the countries which they now inhabit. A
few show a wider range in the immediate past than in the present. Thus
_Lycaon_ (_L. anglicus_) has been met with in caves in Glamorganshire,
while _Icticyon_ of South America appears to be congeneric with _Speothos_
of the Brazilian caves. The African _Otocyon_ seems to occur in deposits in
India. There are also numerous extinct species belonging to the genus
_Canis_, which extend as far back as the Pliocene.

The earlier types of Dogs have been placed in different genera.
_Cynodictis_ is an Eocene form from European strata. The skull is decidedly
Civet-like, with a short snout. The fore- and hind-feet were five-toed,
with well-developed pollex and hallux. The dentition was that of modern
Dogs, the molars being two in the upper and three in the lower jaw. The
general aspect of the creature and the form of the skeleton was much like
that of the Viverrine genus _Paradoxurus_, of which, as well as of the
Dogs, _Cynodictis_ might have been an ancestor.

_Simocyon_ of the Upper Miocene serves as the type of a separate sub-family
of Dogs, Simocyoninae. The skull is short, broad, and high; the shortening
of the skull affecting the jaws has reduced the teeth greatly; the first
three premolars are very small, fall out soon, and are thus often
deficient. There are only two molars in each jaw. This type is of course
nowhere near the ancestral Dog. It is a much-specialised branch of an early
type. _Cephalogale_ is less specialised; there are the usual four
premolars. _Enhydrocyon_ is an intermediate form; it has lost one premolar
in each jaw.

_Amphicyon_, forming the type of another sub-family, Amphicyoninae, though
usually placed among the Dogs, presents us with {424} many Bear-like
features in its organisation. The feet, for instance, were plantigrade and
five-toed. The ulna and the radius are specially compared with the same
bones in the Bear tribe. The skull on the other hand is as distinctly
Dog-like in form. The molars are large, broad, and crushing, and Bear-like.
The largest known species, _A. giganteus_, is of about the size of the
Brown Bear. _Amphicyon_ is a Miocene genus. Eocene and allied to it is
_Pseudamphicyon_. This genus has, like _Amphicyon_, the complete dentition
of forty-four teeth. In the Amphicyoninae generally the feet are five-toed,
the humerus has an entepicondylar foramen and the femur a third trochanter.
The upper molars are large.

The closely allied and American genus _Daphaenus_ has also plantigrade
feet, and has in its structure many reminiscences of the Creodonts. So,
too, has the Eocene _Uintacyon_.

_Cynodesmus_ is closely allied to _Cynodictis_. It has ancient features
combined with quite modern ones. The skull is described as being
Creodont-like, but the dentition is that of the microdont modern Dogs. In
accordance with its age the cerebral convolutions of this Dog are much
simpler than in existing Dogs, and the hemispheres do not cover the
cerebellum so much.

THE BEAR-LIKE CARNIVORA OR ARCTOIDEA.--That division of the Carnivora which
is typically represented by the Bears embraces three recent families, which
are united by a number of characters. These Carnivora are always
plantigrade or nearly so. They have nearly always five toes. The claws are
not retractile, or at most semi-retractile as in the Panda. In the skull
the tympanic bulla is often depressed, and is not so globular and obvious
as in the Cats. Its cavity is not divided by a septum. The paroccipital
processes are not applied to it. The carnassial tooth is less emphasised in
this group than in the Cats.

These characters, however, have to be used with caution, as they are hardly
universally applicable. A fairly typical Arctoid bulla is seen in such a
form as _Cercoleptes_. The bulla itself is a little more swollen than in
_Ursus_, but it is flattened off in the same way towards the bony meatus.
The paroccipital processes, slightly developed, are at a distance of ¼-inch
from the posterior margin of the bulla. In the Raccoon the bullae are much
more swollen, and the paroccipital processes are closer to them. In the
Marbled Polecat, _Putorius sarmaticus_, the bullae are fairly {425}
swollen, and there is but little flattening towards the meatus: the
paroccipital processes, though slight, are in contact with the bullae
basally, though their free tips are turned away from them. Finally, in
_Ictonyx_ the bullae are much swollen; there is but little flattening
towards the meatus, and the paroccipital processes, themselves much
swollen, are pressed closely against the bullae. The Mustelidae, therefore,
in this as in other characters, approach the Aeluroids.

[Illustration]

FIG. 212.--Section of the left auditory bulla and surrounding bones of a
Bear (_Ursus ferox_). _am_, External auditory meatus; _BO_, basioccipital;
_Car_, carotid canal; _e_, Eustachian canal; _g_, glenoid canal; _Sq_,
squamosal; _T_, tympanic; _t_, tympanic ring. (From Flower, _Proc. Zool.
Soc._ 1869.)

There is no caecum, a feature which marks off the Arctoidea from all
Carnivora except the Viverrids _Nandinia_ and _Arctictis_ (occasionally).
The brain is characterised by the possession of what Dr. Mivart has
described as the "ursine lozenge," a tract about the middle of the
hemispheres, defined posteriorly by the crucial sulcus, and formed by the
emergence on to the surface of the brain of the hippocampal gyrus.

The Arctoidea are very widely distributed. But there are some curious
exceptions. Thus there are no representatives of the group (as might be
expected) in the Australian region; they are completely absent from
Madagascar; while the true Bears (family Ursidae) are totally absent from
Ethiopian Africa, and are only represented by a single species, _Ursus
ornatus_, in the Neotropical region.

It is noteworthy that the Arctoidea never show spots or {426} cross stripes
(save rings on the tail), which are so common a feature of the coloration
of the Cat-like forms.

In bracketing together the three families which are described in the
following pages, emphasis is laid upon a number of undoubtedly common
features. Palaeontology seems, however, to suggest that the Mustelidae come
nearer to the Viverridae. That the Bears and Dogs are connected by extinct
annectent genera does not interfere with their present distinctness.

The systematic arrangement of these Carnivora is not easy. It may be
useful, however, to give a method of arrangement for the convenient placing
of the genera.

The most primitive group is perhaps that of the true Bears, family Ursidae;
for in them the molars are two above and three below, and have thus not
become diminished in number as in some of the other members of the order.
Moreover, the Bears have lobate kidneys, which character, often occurring
in the young of animals which when adult have smooth kidneys, may be looked
upon as a primitive character. The feet furthermore are completely
plantigrade. This family will contain only three genera, _Ursus_,
_Melursus_, and _Aeluropus_.

Next comes the family Procyonidae, in several members of which one molar is
lost below, though in others the more archaic formula is retained. The
kidneys are simple. This family contains the American genera _Procyon_,
_Nasua_, _Bassariscus_, _Bassaricyon_, _Cercoleptes_, and the Old-World
form _Aelurus_.

The third family, Mustelidae, has the molar formula reduced to 1/2 or 1/1.
The kidneys are simple except in the Otters. To this family are assigned
the following genera:--_Arctonyx_, _Conepatus_, _Meles_, _Mephitis_,
_Taxidea_, _Mydaus_, _Mellivora_, _Helictis_, _Ictonyx_, _Mustela_,
_Galictis_, _Grisonia_, _Putorius_, _Gulo_, and the aquatic _Lutra_,
_Enhydris_, and _Aonyx_.

FAM. 6. PROCYONIDAE.--This family is mainly American in range, the genus
_Aelurus_ alone being a native of the Old World. But Zittel would include
with the genera of this family the Viverrine and Oriental genus
_Arctictis_, a proceeding which is perhaps hardly admissible, though the
occasional absence of a caecum in that animal is so far in favour of such
an alliance. The largely vegetable nature of its food and its arboreal
habits cause a certain amount of likeness to some of the members of the
present group of Carnivores. The Procyonidae have two {427} molars in
either half of each jaw. The carnassial teeth are not typically developed,
and the molars are broad and tuberculate. The tail is long, often
prehensile, and often ringed in the disposition of its colour pattern. The
alisphenoid canal is absent save in the aberrant _Aelurus_. Both condyloid
and postglenoid foramina are present. The members of this family are
plantigrade.

[Illustration]

FIG. 213.--Raccoon. _Procyon lotor._ × 1/5.

The genus _Procyon_ includes at least two species of Raccoon, the northern
form, _P. lotor_, and the South American, _P. cancrivorus_. To these may
possibly be added a third, _P. nigripes_. This genus is characterised by
the length and the mobility of the fingers, and indeed it uses its hands
greatly. It has no median groove upon the muzzle, which is found in many
other Arctoids; the ears are moderately large; the tail is not long, being
about one-third of the entire length of the animal, including the tail. The
soles of the feet are naked. Its limbs are very long (for an Arctoid), and
this gives to the animal a bunched-up appearance when walking. There are
four premolars and two molars on each side of each jaw. There are fourteen
pairs of ribs, of which ten pairs reach the sternum. The latter is composed
of nine pieces.

The first-named species has received its name from the fact--of which there
is abundant proof--that it dips its food into water. As a matter of fact,
the animal frequents the margins of streams, and hunts in the shallow water
beneath stones for {428} crayfish, and it also captures fish. Not only is
this animal partially aquatic, but it can climb well--"they make their
homes in trees, but carry on their business elsewhere." The animal can be
readily tamed, but is a tiresome pet on account of its insatiable curiosity
and its skill in the use of its hands, which enables it to unlatch doors
and generally to pry about everywhere. The Raccoons are mostly nocturnal
creatures.

The genus _Bassaricyon_[296] includes two species, both American, _B.
alleni_ being from Ecuador, and _B. gabbii_ from Costa Rica. They have so
much the aspect of a Kinkajou that a specimen, which arrived at the
Zoological Gardens, was presented and entered as one of those animals.
Nevertheless there are many differences between the two genera. The tail of
_Bassaricyon_ is not prehensile, and the animal, as will be seen from Fig.
214, has a sharper snout; the brain is more like that of _Bassariscus_. The
likeness to _Cercoleptes_ can hardly perhaps be regarded as an example of
"mimicry" since the forms are so nearly related, and the advantage of such
an imitation remains to be proved. The muzzle of _Bassaricyon_ is grooved;
the ears are fairly large; the soles of the feet are naked; there is but a
single pair of teats. There are two molars and four premolars to each half
jaw.

[Illustration]

FIG. 214.--Bassaricyon. _Bassaricyon alleni._ × 1/5.

The dorsal vertebrae are thirteen in number; nine of the ribs reach the
sternum. The slenderness and convexity of the lower margin of the lower
jaw, as well as the feeble angular process, distinguish this genus from its
undoubtedly near ally _Cercoleptes_. The dental formula also is different.

_Bassariscus_ has a ringed tail like a Raccoon, and is also American in
range; it furthermore agrees with the Raccoon in {429} being nocturnal and
mainly arboreal in habit. There are apparently three species, of which _B.
astutus_ is the best known, having been on several occasions exhibited at
the Zoological Society's Gardens, the last examples so lately as 1900. The
animal was for a long time believed to be allied to the Oriental
Paradoxures, and its occurrence in America was therefore puzzling. The real
affinities of the creature were, however, definitely set at rest by Sir W.
Flower, and later accounts of its anatomy have confirmed this opinion.[297]
The vertebrae are more numerous than in _Procyon_, and the teeth are
slightly different; otherwise it presents many likenesses to its nearest
ally. The ears are long; the nose is grooved; and the palms and soles are
naked.

[Illustration]

FIG. 215.--Cunning Bassarisc. _Bassariscus astutus._ × 1/5. (From
_Nature_.)

The Kinkajou, _Cercoleptes_, is likewise an American Arctoid. It ranges
from Central Mexico down to the Rio Negro in Brazil. It was at one time
confounded, and, considering its external appearance, not unnaturally, with
the Lemurs. Sir R. Owen dispelled this view by a careful dissection of the
creature. Nevertheless, there are certain anatomical features in which it
differs {430} from Carnivora and resembles Lemuroids.[298] It has been
pointed out that the form of the lower jaw "much resembles that of the
Lemuroid _Microrhynchus_." There is, however, no doubt that it is rightly
placed in the present group. The tail is very prehensile, and the animal is
therefore, as might be supposed from this circumstance, purely arboreal. It
has some twenty-eight vertebrae. This genus has a median groove upon the
nose. The claws are long and sharply pointed, and the palms and soles of
the feet are naked. The premolars are three, the molars two. There are
fourteen dorsal vertebrae, of which nine are united to the nine-jointed
sternum by ribs. There is but one species, _C. caudivolvulus_, of a uniform
yellowish-brown colour.

[Illustration]

FIG. 216.--Kinkajou. _Cercoleptes caudivolvulus._ × 1/6.

[Illustration]

FIG. 217.--Coati. _Nasua rufa._ × 1/6.

_Nasua_, the Coati, ranges from Texas to Paraguay, and has two species. In
Guatemala it reaches a height of 9000 feet on the mountains. The nose is
produced into a short and very {431} mobile proboscis, hence its name. The
native Mexican name for the creature is "Quanhpecotl."

The Coati is largely arboreal, and hunts iguanas in large bands, some of
them being on the trees and some on the ground beneath. It also grubs up
worms and larvae, for which purpose its long snout is suited. The molars of
the genus resemble those of _Procyon_.

There is not a median groove upon the nose. The palms and soles are naked.
Six teats occur. There are thirteen dorsal vertebrae. _Nasua nasica_[299]
and _N. rufa_ are the best known and perhaps the only species. The colour
of the fur varies a good deal, and has led to the use of other names for
supposed species.

_Aelurus_, the Panda, is a largish animal found in the south-eastern
Himalayas up to a height of 12,000 feet. It has a glossy fur of a reddish
colour, and a "white somewhat cat-like face." The molar formula which
distinguishes it from the New-World Arctoids belonging to the Procyonidae,
as well as from its possible ally _Aeluropus_, is Pm 3/4 M 2/2. The anatomy
of the animal has been described by Sir W. Flower.[300] Dr. Mivart has
pointed out that the muzzle though short is upturned in a way distinctly
recalling that of _Nasua_. The animal inhabits forests, and feeds almost
entirely upon vegetable food. It eats eggs, however, and insects. Though
living to a great extent upon the ground, it is also arboreal, and has
sharp semi-retractile claws. It is said to be dull of sight, hearing, and
smell, and yet with these disadvantages is also unprovided with cunning or
ferocity. Its habits have been compared with those of a Kinkajou.

FOSSIL PROCYONIDAE.--In addition to several of the existing genera, the
remains are known of various extinct forms of Procyonidae. _Leptarctus_,
with one species, _L. primaevus_, is of Pliocene age, but is known only by
one ramus of the lower jaw. It appears to "offer a number of transitional
characters between the more typical Procyonidae and the aberrant
_Cercoleptes_."[301]

FAM. 7. MUSTELIDAE.--Contrary to what has been stated with regard to the
habits of the Procyonidae, the Mustelidae are for the most part
"bloodthirsty robbers," and are spread over the {432} whole surface of the
world, with the exception of Australia and Madagascar. The molar teeth are
generally reduced to one in the upper jaw, and sometimes to one in the
lower jaw, which thus gives "a sort of _prima facie_ resemblance to the
feline dentition." There is no alisphenoid canal; postglenoid and condyloid
foramina are found.

SUB-FAM. 1. MELINAE.--Of this sub-family there are representatives both in
the Old and New Worlds.

[Illustration]

FIG. 218.--Badger. _Meles taxus._ × 1/6.

_Meles_, the Badger, is exclusively Palaearctic in range.[302] Dr. Mivart
says that _Meles_ has a relatively longer dorsal region than any other
Carnivore, and that it is most nearly approached by its allies _Ictonyx_
and _Conepatus_. The molar formula is, as in _Arctonyx_, _Mydaus_, and
_Helictis_, Pm 4/4 M 1/2. The molars differ from those of any other
Carnivore in the much greater size of the first molars than of the last
premolars. The nose is not grooved; the soles of the feet are naked. The
claws of the fore-feet are much longer than those of the hind-feet.

The genus _Arctonyx_ is a "pig-like badger" from Hindostan, Assam, and
North China. The epithet "pig-like" is derived from the long and mobile
snout, which is truncated and has terminal nostrils. It is remarkable for
having a part of the palate formed by the pterygoids, as in Whales and
certain Edentata (e.g. _Myrmecophaga_). There are sixteen dorsal vertebrae.
_A. collaris_ lives in {433} fissures of rocks, or in holes dug by itself.
It is a purely nocturnal beast.

The singular genus _Mydaus_, containing the species _M. meliceps_, the
Teledu or Javanese Skunk, is an inhabitant of Java and Sumatra. It
frequents the mountains of these islands, into the soil of which it burrows
in search of worms and larvae. There is but one species, which is "like a
miniature badger, of rather eccentric colours." It is blackish brown, with
a yellowish-white top to its head, and a stripe of the same colour down the
back. It may be distinguished by its elongated snout, obliquely truncated,
and with inferiorly-placed nostrils. As to osteological characters, it has
a more oblique symphysis of the mandible than in any other Carnivore. The
secretion of the anal glands is said to rival that of the Skunk in
offensiveness and in the distance to which it can be propelled.

SUB-FAM. 2. MUSTELINAE.--Representatives occur in both the Old and New
Worlds; but the genera and even the species are in one or two cases common
to both.

[Illustration]

FIG. 219.--Tayra. _Galictis barbara._ × 1/7.

_Galictis barbara_,[303] the Tayra, is a brown, elongated, and Weasel-like
animal from Mexico and South America. As is the case with the Weasel, it is
sometimes gregarious, a herd of twenty having been observed. The soles of
the feet are naked, and the molar formula is Pm 3/3 M 1/2. In these
characters the Grison (_G. vittata_) agrees with _G. barbara_; but it has
been referred to a different genus, _Grisonia_.

The Grison, "this savage and diabolical-looking weasel," as {434} Mr. Aplin
terms it,[304] is known also as the "Hurón." It almost rivals the Skunk in
the power of the odour which it can emit when enraged. A trapped specimen
was placed in a cage 50 yards or so from the house, and even at this
distance it was disagreeably easy to tell when any one visited the
animal--at least when the wind set in the right direction. It is greyish
yellow above and blackish beneath, presenting, as has been remarked, a
curious similarity to the Ratel. The nose of this animal is destitute of a
median groove, which is present in the Tayra; the soles of the feet,
however, are naked as in that animal, and it is nearly plantigrade in walk.
It differs also from _Galictis_ in having sixteen[305] instead of fourteen
dorsal vertebrae. Eleven of the ribs reach the sternum. Considering the
differences that exist between some other genera of Arctoids, it may be
fairly allowed that a genus _Grisonia_ is tenable.

[Illustration]

FIG. 220.--Grison. _Grisonia vittata._ × 1/7.

_G. allamandi_ is darker coloured than the Grison, with a white band from
the forehead to the neck. Mr. T. Bell described a tame individual as eating
eggs, frogs, and even a young alligator.

A third genus of this group has recently been founded by Mr. Oldfield
Thomas[306] for a small African animal, which is Grison-like in its
coloration. The name given to the genus, _Galeriscus_, is intended to
suggest its likeness to the Grison (_Galera_ or _Grisonia_). The chief
distinctive feature of this genus, whose skeleton is not yet known, is the
presence of only four digits on each limb; the pollex and the hallux being
entirely absent. The ears of this Grison are short. {435}

The genus _Mustela_ includes the Martens and Sables, which are
distinguished from the following genus by the molar formula, which is
Pm 4/4 M 1/2. The same character separates them from _Galictis_, and also
the generally hairy under surface of the feet. In more southern latitudes,
however, the palms are sometimes naked. The nose is grooved, and the ears
are short and broad. The genus is widely distributed, being common to the
Old and New Worlds. In the Old World it extends from Europe to Java,
Sumatra, and Borneo. The largest species of the genus is the American
Pekan, an animal which may be 46 inches in length, including the tail.
There are two species of Sable, one European (_M. zibellina_), the other
American.

The only British species of the genus is the Pine Marten, _M. martes_. It
is dark brown, with a brownish-yellow throat, and reaches a length of some
17 inches, with an eight-inch tail. It is getting rare, but is still fairly
common in the Lake country. The animal is largely arboreal in habit, whence
the vernacular name. It is also called Marten Cat. The allied _M. foina_,
the Beech Marten, has been stated to be, but apparently is not, an
inhabitant of these islands. The colour of the animal is a rich brown. It
has small eyes and ears and a short tail. The palms of the hands and the
soles of the feet are hairy; the muzzle is naked, and has a groove as in
_Cercoleptes_, etc.

The Glutton, _Gulo_, is a well-marked genus, containing but one species,
which is circumpolar in range. The dentition is Pm 4/4 M 1/2. The ferocity
but not the voracity of this animal appears to have been exaggerated. It
mainly feeds on carcases, and is not really a successful hunter. As to the
carcases, Olaus Magnus tells in straightforward language the way in which
the animal dilates in size during a meal, and presently, after following
the practice of the ancient Romans, returns to the banquet: "Creditur a
natura creatum ad ruborem hominum qui vorando bibendoque vomunt redeuntque
ad mensam"!

This is one of the few land animals which ranges completely round the pole.
There is no difference to be noted between the Old-World and the New-World
specimens. It is now an entirely northern form, but in Pleistocene times it
reached as far south as this country. The fossil species seems to be _Gulo
luscus_, and to be quite indistinguishable from the living forms.

_Putorius_, the genus which embraces the Weasel tribe, contains {436} many
species known popularly as Weasels, Ermines, Stoats, Ferrets, Polecats,
Minks, and Vison. Not only is the genus common to both Old and New Worlds,
but in a few cases the species (e.g. _P. erminea_) range from Asia to
America. The molar formula is Pm 3/3 M 1/2. The form of the body is an
exaggerated one, the length of the trunk to the limbs being very great. The
feet are more or less hairy beneath, and the animals are digitigrade. The
nose is grooved. The dorsal vertebrae vary from thirteen to sixteen.

[Illustration]

FIG. 221.--Polecat. _Mustela putorius._ × 1/6.

There are four British representatives of this genus:--

The Polecat, _P. foetidus_, is a dark brown-coloured animal. Its total
length is about 2 feet, of which the tail occupies some 7 inches. It is a
species banned by the gamekeeper, and hence is approaching extinction in
this country. It is excessively bloodthirsty, as are apparently all the
members of this genus, and kills out of mere wantonness. The Ferret is
simply a domesticated variety of the Polecat.

The Stoat or Ermine, _P. erminea_, is reddish brown above, white beneath.
In winter, in certain localities, it becomes white with the exception of
the black tip of the tail. This colour-change bears some relation to the
degree of latitude. It is universal in the north of Scotland, rare in the
south of England. As is the case with some other animals that generally
change {437} their colour in the winter, there are individuals which seem
to have lost the power of change, and others which change in an apparently
capricious manner, not influenced by season or cold. Like so many other
animals, the Stoat appears at times to migrate, which it does in large
parties. Such parties are said to be dangerous, and will attack a man who
crosses their path.

The Weasel, _P. vulgaris_, has much the same colour as the Stoat, but is a
smaller animal; it differs also by undergoing no seasonal change. It is
equally agile and ferocious, and ought to be encouraged, as it vents its
ferocity largely upon Voles and Moles, which it can pursue underground.
Like other species of _Putorius_, it seems to kill its prey by biting
through the brain-case.

The fourth British species is the recently-described Irish Stoat, _P.
hibernicus_. It is somewhat intermediate between the last two.

_Poecilogale_ is a genus recently instituted by Mr. Thomas for a small
South African Weasel, _P. albinucha_, coloured like the Zorilla, _i.e._
with whitish stripes upon black, but differing in its reduced molar
formula, which is Pm 2/2 M 1/1 or 1/2.

_Lyncodon_[307] is thought to be more doubtful; it is South American
(Patagonian), with the same molar formula as the most reduced forms of the
last genus, _i.e._ Pm 2/2 M 1/1. The ears are short and almost invisible;
the claws of the anterior limbs are long, those of the hind limbs short. It
is not quite certain that it is not "an aberrant southern form of _Putorius
brasiliensis_." That its distinction is justifiable appears to be shown by
the discovery in the same region of a fossil species, _L. luganensis_.
Matschie places it near _Galictis_.

The Ratel, _Mellivora_, is common to India and West and South Africa. It is
a black animal with a grey back and grey on the top of the head, the
contrast of colour suggesting a dorsal carapace. It runs with a swift trot.
The animal lives much on the ground, but can climb trees. It is exclusively
nocturnal in its habits. It has the reputation in India of feeding upon
dead bodies, a view which has probably no foundation in fact save that it
can burrow. The molar formula is Pm 3/3 M 1/1. There are fourteen dorsal
vertebrae. The African and Indian species are {438} hardly to be
distinguished from each other. The ears are very minute. The tail is short.
The muzzle is rather pointed, and the soles and palms are naked.

[Illustration]

FIG. 222.--Ratel. _Mellivora capensis._ × 1/8.

The structure of _Helictis_ has been described by the late Professor
Garrod,[308] as well as by Sir W. Flower in his general account of the
Carnivorous skeleton. The animal, which is a native of East Asia, is
sometimes gaily coloured. _H. subaurantiaca_, the species dissected and
figured by Garrod, is a varied black and orange. The genus is arboreal, and
the tail may be moderately long and bushy. The ears are small; the nose is
grooved; the palms are naked, but the soles of the feet are hairy. There
are fourteen dorsal vertebrae. The molar formula is Pm 4/4 M 1/2.

The Zorilla, _Ictonyx_, is the last of the Old-World genera of Melinae. It
is African, ranging from the tropical parts of the continent to the Cape.
"In colour and markings," remarks Dr. Mivart, "as well as in the odour of
the secretion of its anal glands, the one or two species which form this
genus resemble the skunks; so much so that did they inhabit the same
region, and were they devoid of an offensive secretion, they would
certainly be said to mimic the skunks." The molar formula of the genus is
Pm 3/3 M 1/2. There are fifteen dorsal vertebrae. The nose is grooved and
the soles partly hairy.

The American Badger, _Taxidea_, is a burrower of omnivorous tastes, and
correlated with the former habit are the immense {439} claws of the
fore-paws. It is North American, but gets into Mexico. The molar formula is
as in the American genera _Mephitis_ and _Conepatus_, and as in the
Old-World _Ictonyx_, and it thus differs from that of _Meles_. Besides the
great size of the claws upon the hand, which are larger relatively than
those of any other Carnivore, the genus _Taxidea_ is to be distinguished
from all Arctoids (indeed, from all Carnivora) except _Mydaus_, by the fact
that the pelvic limb is of the same length as the pectoral. The muzzle is
furry except at the very extremity; this is grooved. The animal is
carnivorous, subsisting upon the following very varied kinds of
food--"Spermophiles, Arvicolas, birds' eggs, and snails, also honey-comb,
wax, and bees."

The Skunk, _Mephitis_, is an American animal with several species, which
range from North to Central America. The black-and-white colour
distinguishes the genus, which is furthermore marked by the fact that the
third digit of the hand is relatively longer than in any other Carnivore
except _Taxidea_. The soles are partly hairy. It is a terrestrial fossorial
animal with well-known powers of protecting itself from aggression. But
nevertheless the Skunk has its enemies, and is not quite so unmolested as
is sometimes popularly supposed. The Puma, Harpy Eagle, and the Great
Horned Owl will at least occasionally attack and devour it. The molar
formula is Pm 3/3 M 1/2. There are sixteen dorsal vertebrae.

_Conepatus_ is a more southern form of Skunk, extending down into South
America. Its dentition is like that of _Mephitis_ save for the loss of an
upper premolar. This genus, which has been further subdivided, differs from
_Mephitis_ in the fact that the soles of the feet are wholly naked, whereas
in Mephitis those of the hind-limbs are partially hairy. It has no groove
on the nose. Its tail is shorter than that of _Mephitis_. This Skunk has
the same habits as the last. In certain parts of South America the animals
are so abundant and their odour so powerful that in the evening there is
generally a recognisable smell about. This is said to be good for the
headache!

SUB-FAM. 3. LUTRINAE.--Of this sub-family there are at least two genera.
_Enhydris_ (_Latax_),[309] the Sea-Otter, is confined to the shores of the
North Pacific. It is more purely aquatic than are {440} other Otters.
Specimens have been seen swimming fifteen miles from land. The gait of the
creature when on land is suggestive of a marine animal; the webbed
hind-feet are doubled back upon the knuckles during progression upon land,
and locomotion is effected by a series of short springs from these feet;
the Otter does not walk "in ordinary acceptance of the term." The tail is
flattened, being twice as broad as it is thick, and ends in a bluntish
point. _Enhydris_ feeds mainly upon crabs and sea-urchins, but also upon
fish. Its dental formula is peculiar by reason chiefly of the reduction of
the lower incisors. The formula runs as follows: I 3/2 C 1/1 Pm 3/3 M 1/2.

The molar teeth of this creature, in accordance with its diet, have lost
the sharp points of the Mustelidae in general; the crowns are flattened,
and the tubercles very blunt. In this it contrasts with _Lutra_, and
presents some resemblance to the Crab-eating Raccoon, _Procyon
cancrivorus_; but the teeth are still further blunted. _Enhydris_ feeds
largely upon sea-urchins and shell-fish, and needs blunt teeth for the
crushing of the hard shells of its prey. It is interesting to notice that
the habits of this animal have been altered by the interference of man. The
creature has been hotly pursued for a long time on account of its valuable
fur. Instead of feeding and breeding upon the shore in places readily
accessible to its pursuers, the Sea-Otter has now taken to the open sea in
a greater degree. It utilises masses of floating seaweed for those
purposes, and hunts for its food in the deeper water at a greater distance
from the shore. In conjunction with the increasing rarity of the Sea-Otter
the price of its skin has enormously increased: whereas in 1888 the average
price per skin was £21:10s., the value of a fine skin now is at least £100,
and as much as £200 and even £250 has been given. The animal is captured by
netting and by clubbing and spearing.[310] From the Miocene Siwalik beds
remains of an allied form, _Enhydridon_, have been obtained, whose teeth
are somewhat intermediate in their crowns between _Lutra_ and _Enhydris_.

_Lutra_, including the Otters, is widely distributed. Both manus and pes
are webbed. The ears are small and hairy. The nose is not grooved, and the
naked part is very circumscribed; {441} the claws upon the hind-feet are
flattened and somewhat nail-like. There are about ten species, but of
course, as is so universally the case, a great many more names have been
given. The molar formula is like that of _Enhydris_ save that there is an
extra premolar in the upper jaw. There are fourteen pairs of ribs, of which
eleven pairs reach the ten-jointed sternum. The caudals are twenty-three.
The Cape Otter, the "clawless" Otter, has been separated as a genus
_Aonyx_. So too has the South American _Pteronura brasiliensis_. But in
neither case is the separation allowed by Mr. Thomas in a recent revision
of the genus.[311] The latter species has the reputation of being very
fierce, and is known in Uruguay by the name of "Lobo de pecho blanco." The
British species, _L. vulgaris_, reaches a length of 2 feet or so, with a
tail of 16 inches; it ranges over the whole of Europe and a large portion
of Asia. This Otter often burrows in the banks of the streams which it
frequents; and in the burrow in March or April the female brings forth her
young, three to five in number. It will also frequent the sea-coast.

[Illustration]

FIG. 223.--Otter. _Lutra vulgaris._ × 1/6.

FOSSIL MUSTELIDAE.--Besides a number of the existing genera there are
fossil members of this family which cannot be referred to existing genera.
These latter extend back into time as far as the Eocene. _Stenoplesictis_,
one of these Eocene forms referable to the sub-family Mustelinae, is to be
distinguished {442} from living Mustelines by its comparatively long legs.
In this genus as in several others there are two upper molars.

FAM. 8. URSIDAE.--This family is nearly universal in distribution, and
consists of but three genera, _Ursus_, _Melursus_, and _Aeluropus_.

_Ursus_ has the palms and soles naked except in the Polar Bear, which needs
a furry sole to walk with ease upon ice surfaces. The ears are fairly
large, and the nose may or may not be traversed by a median groove.[312]
The molar formula[313] is Pm 4/4 M 2/3. The brain is naturally (because of
the size of the animals of this genus) richly convoluted. The lobate
kidneys have already been mentioned in defining this family (see p. 426).

[Illustration]

FIG. 224.--Himalayan Bear. _Ursus tibetanus._ × 1/15.

A very large number of species of Bears have been described. But it is the
opinion of Mr. Lydekker[314] and of others that many of these are really to
be referred to the European Brown Bear; in this event the Grizzly of North
America, the Isabelline Bear, the Syrian Bear, a Bear from Algeria, the
Kamschatkan and Japanese Bears, besides the extinct _Ursus fossilis_ of
Pleistocene caves, are to be regarded as slight modifications of _Ursus
arctos_. On the other hand, the great Cave Bear, _U. spelaeus_, {443} and
the Thibetan Blue Bear (_U. pruinosus_) are distinct species, not to be
confounded with _U. arctos_. Neither, of course, are the Peruvian _U.
ornatus_ and the Sun Bear, _U. malayanus_.

[Illustration]

FIG. 225.--Malayan Bear. _Ursus malayanus._ × 1/12.

The Polar Bear has even been placed in a separate genus, _Thalassarctos_, a
proceeding which is quite unnecessary. The white colour of this Bear tends
to become browner with age. It is one of the few mammals which extend right
round the pole; the Polar Bear is of course a purely Arctic animal. The
chief food of the Polar Bear is Seal. Out of thirty Bears examined, Mr.
Koettlitz found that only fifteen had animal remains in their stomachs, and
these remains were invariably Seal. The animal apparently hunts by scent
rather than by sight or hearing, both of which senses seem to be somewhat
dull. The males and females wander separately, except of course during the
breeding season. The Bears dig holes in which they may remain for some
time, but there is no hibernation. In Pleistocene times, the Polar Bear
extended as far south as Hamburg. The female has four mammae, pectoral in
position.

_Melursus_ includes only _M. labiatus_, the Sloth Bear of India. This
animal has an upturned snout, which is described as closely resembling that
of _Mydaus_, the Teledu. The snout has no groove. {444} All Bears are
largely vegetarian and insect feeders; but this Bear is especially so. It
delights in the nests of Termites, and its energy in destroying these hills
for the sake of their inhabitants is so great that the name of "sloth"
appeared to Sir Samuel Baker to be an entire misnomer.

_Aeluropus_, a rare Carnivore with but one species, _A. melanoleucus_, is
not inferior in size to the Brown Bear, and is distinguished by its largely
white coloration. It was discovered in the mountains of East Thibet by Père
David, and described by Milne-Edwards[315] as a distinct and new genus, the
discoverer himself having named it as a species of _Ursus_. It is a
vegetable-feeding creature and bulky in form, with a rudimentary tail and a
short broad head; in fact, more like a Bear than a Procyonid (with which
group it is placed by some). The width of the head, however, is greater
than in any other Carnivore; it is most closely approached in this by
_Aelurus_ and by _Hyaena_. The molar formula is Pm 4/3 M 2/3. The soles are
hairy. There is no alisphenoid canal. The molars are especially large and
multicuspid.

[Illustration]

FIG. 226.--_Aeluropus melanoleucus._ × 1/12.

FOSSIL URSIDAE.--The genus _Ursus_ itself goes back to Pliocene times. The
well-known Cave Bear, _Ursus spelaeus_ of {445} Pleistocene times, was one
of the commonest of Carnivorous creatures during the very early times of
the present era. It was as huge as a Polar Bear or a Grizzly. The skull is
remarkable for the fact that the first three premolars, which are small in
all Bears, dropped out early in life. An immense number of names have been
given to what are in all probability the same species as this Cave Bear of
remote antiquity.

_Hyaenarctos_ is the oldest genus of true Ursidae. It goes back into Middle
Miocene times, and ranged over Europe and North Africa.

_Arctotherium_ is an American genus of Pleistocene times. The likeness of
some of the extinct Canidae to Bears has been already commented upon.

       *       *       *       *       *


{446}

CHAPTER XIV

CARNIVORA (_CONTINUED_)--PINNIPEDIA (SEALS AND WALRUSES)--CREODONTA

SUB-ORDER 2. PINNIPEDIA

This group includes the Seals, Sea-Lions, and Walruses,[316] all aquatic
and, for the larger part, marine creatures. Being aquatic they have to some
extent acquired a fish-like form, though not so completely as have the
Whales and even the Sirenia. This is most complete so far as the group is
concerned in the Seals, where the hind-limbs have become soldered to the
tail and are inefficient as walking legs, where the external ears have
vanished, and where the general shape of the body is tapering and thus
fish-like. The Walruses and Sea-Lions are less modified in this direction;
in the latter (not in the former) the external ear, though small, is
persistent, and the hind-limbs are capable of being used as organs of
progression upon dry land. The general characters applicable to the
Carnivora, given upon a previous page, apply to the Pinnipedia.

[Illustration]

FIG. 227.--Skeleton of Seal. _Phoca vitulina._ (After de Blainville.)

The characters confined to the Pinnipedia as a whole are mainly these:--The
greater part of the limbs are enclosed within the skin, the hands and feet
are fully webbed, and there is a tendency for the nails to disappear, and
for the phalanges to increase in number--characters which are clearly not
diagnostic of the order but correlated with an aquatic life, since they
reappear, and are indeed exaggerated, in the Cetacea. The teeth are
peculiar in that the milk dentition is feeble and is early shed. This, as
it were, undue emphasis upon one of the two sets of teeth is another
likeness to the Whales, {447} where, however, it is the milk dentition that
is most pronounced, the "permanent" being feeble and very early shed. But
the dentition of the Pinnipedes presents other likenesses to the Cetacea,
which are, it must be remembered, regarded by some as a modification of the
Carnivorous stock, in which case, of course, the likenesses may be genetic
rather than due to adaptation in the two cases. There is a distinct
tendency towards a homodont series, the grinding teeth being often very
simple, and the very distinct carnassial tooth of many terrestrial
Carnivores being absent. Finally, the number of the back teeth shows some
signs of being on the increase; and Professor Kükenthal has found that this
increase is due to the division of existing teeth. Here is a point of
likeness to the many teeth of the typical Toothed Whales. Dr. Nehring found
in several examples of _Halichoerus grypus_ the normal five back teeth
increased to {448} six, and the additional molar was at the end of the
series, thus suggesting a lengthening of jaw coupled with an increase in
number of teeth.

The incisor teeth of the Pinnipedia differ from those of the land Carnivora
in that there are nearly always fewer than 3/3, at least in the adult
animal. In possessing lobulated kidneys the Pinnipedia differ from all
terrestrial Carnivores except the Otters and Bears--a significant fact.

In the characters of the skeleton the Pinnipedia show many peculiarities.
The cranial part of the skull is proportionately to the facial part greater
than in terrestrial Carnivora; there is no lachrymal bone, and the orbit is
to some extent defective in ossification. The alisphenoid canal, so
important a feature in the Carnivora, may be present or absent. It is
present, for example, in _Otaria jubata_.[317] This genus also has the more
primitive small and rugged tympanic bullae, which are inflated and more
Cat-like in others. The vertebrae show an interesting Creodont peculiarity
in the complex interlocking arrangements of the zygapophyses of the dorsal
vertebrae. The ossicula auditus differ from those of their terrestrial
allies in their large size and massive growth. In this they have come to be
like those of the Whales and Sirenians.

[Illustration]

FIG. 228.--Patagonian Sea-Lion. _Otaria jubata._ × 1/20.

There is no doubt about their close resemblance to the {449} terrestrial
Carnivora, but the question is, to which group of Carnivora have they the
most likeness. The semiaquatic Otter, and the still more thoroughly aquatic
(marine) _Enhydris_, suggest an affinity in that direction. The long body
and short legs of the Otter, which is more thoroughly at home pursuing fish
in the streams than in waddling clumsily upon the banks of the streams,
seem to require but little external change to convert it into a small Seal,
while the long and completely webbed hind digits of _Enhydris_ are even
more like those of a Pinniped. The Sea-Lions, in which the external ear has
been preserved, and in which the limbs have not become so entirely useless
for progression on the land as they have in the Seals, seem to be the
intermediate step in the evolution of the latter. This, however, is not the
opinion of Dr. Mivart, who, without definitely committing himself on the
point, presents some evidence for the assumption that the marine Carnivora
are diphyletic. This double origin, however, is not from two groups of the
terrestrial Carnivora. Dr. Mivart, in common with many others, holds that
the Pinnipedia as a whole are undoubtedly nearer to the Arctoidea than to
either of the two remaining sections of the sub-order. One of the most
striking structural characters in which they show this resemblance is the
brain; the peculiar Ursine lozenge, already treated of as so distinctive a
character of the Arctoidea, is repeated in the Pinnipedia.

There are, however, other points of likeness which seem rather to point to
a Creodont origin. _Patriofelis_ is a genus that from more than one side
may be looked upon as a possible ancestor of these animals. The Creodont
peculiarity of the vertebrae has already been referred to. It may be added
that the facial part of the skull is small in _Patriofelis_, which appears,
moreover, to have had an alisphenoid canal. A very remarkable resemblance
lies in the structure of the astragalus. This is not deeply grooved on the
tibial facet as it is in Fissiped Carnivora. This might be held to be an
instance of degeneration in the aquatic Seals, which do not use their limbs
as walking organs. But Professor Wortman[318] has pointed out that in the
Sea-Otter, which is entirely aquatic, the groove exists and is plain. The
likeness offered to the Seals by the spreading feet of _Patriofelis_ is
noticed under the description of that genus.[319]

{450}

[Illustration]

FIG. 229.--Cape Sea-Lion. _Otaria pusilla._ × 1/16.

FAM. 1. OTARIIDAE.--The family Otariidae[320] is no doubt the least
modified of the aquatic Carnivora. It is rational, therefore, to commence
the survey of the group with this family. They have preserved, as already
noted, the independence of the hind-limbs; the external ear is present,
though small; there is an obvious neck, and the nostrils are at the end of
the snout, as in terrestrial creatures generally. The nails are small and
rudimentary, save those upon the three middle digits of the foot. It is a
singular fact that among the Otaries the angle of the lower jaw is
"inflected as much as in any Marsupial." The literature relating to this
family is great, and it seems difficult to reconcile the very varying
opinions as to how many genera ought to be admitted. Mr. Allen arranged the
nine species which he allowed {451} in six genera; but more generic names
have been proposed. At the other extreme stands Dr. Mivart, who speaks of
only one genus, _Otaria_; of this genus the number of species is by no
means agreed upon. There can, however, be no doubt of the distinctness of
the Northern Fur Seal, _O. ursina_ (the "Seal" of commerce and the cause of
international complications), of the Patagonian Maned Sea-Lion, _O.
jubata_,[321] of _O. pusilla_ of the Cape, of the Californian _O.
gillespiei_, of _O. hookeri_ from the Auckland Islands, and of four or five
others. The range of the genus is wide, but is mainly Antarctic. It is
usual to speak of "Hair Seals" and "Fur Seals," the latter being the
species which produce the "sealskin" of commerce. The difference is that in
the Fur Seals there is a dense, soft under-fur, which is wanting in the
other group. It is, however, impossible to make this character the basis of
a generic subdivision. There is a Fur Seal, _O. nigrescens_, in South
America as well as the more widely-known northern form.

FAM. 2. TRICHECHIDAE.--This family contains but one genus, _Trichechus_,
the Walrus or Morse, or _Odobaenus_, as the more correct term seems to be.
It is a tiresome result of accurate conformity with the rules of priority
in nomenclature that the name _Trichechus_ should be applied to the
Manatee. There is but one species of Walrus, though it has been attempted
to show that the Pacific and Eastern forms are different. The animal is
Arctic and circumpolar. The Walrus is characterised by the enormous canines
of its upper jaw, which form the well-known tusks and reach a length of 30
inches. The animal can progress on land like the Sea-Lions; but, as in the
Seals, there are no external ears, though there is a slight protuberance
above the meatus auditorius. The strong bristles upon the upper lip are as
thick as crow quills. The pectoral limb has nails, but these are small, as
in the Sea-Lions. The under surface of the manus has a warty pad, which
cannot but assist[322] in maintaining a foothold upon slippery ice. The
hind-limbs have longer nails, which are still diminutive and subequal in
size. There is no free tail. The liver of this animal is much furrowed, but
not so much so as in _Otaria_, though more so than in _Phoca_. The kidneys
are of course lobulate, as in the other aquatic Carnivores. The milk dental
formula appears to be I 3/3 C 1/1 Pm + M 5/4. In the adult the formula[323]
is I 1/0 C 1/1 M 3/3.

{452}

[Illustration]

FIG. 230.--Common Seal. _Phoca vitulina._ × 1/8. (From Parker and Haswell's
_Zoology_.)

FAM. 3. PHOCIDAE.--The true Seals have no external ears, and the nostrils
are quite dorsal in position as in other aquatic animals, such as the
Crocodile. There is obviously an approach to the conditions characteristic
of the Whales. The hind-limbs are useless for locomotion on land. They are
bound up with the tail, and form functionally merely a part of the tail. In
this family there are, at any rate, eight genera.

_Phoca_ and _Halichoerus_ are not very wide apart from each other. In both
there are five well-developed claws on feet and hands. They are British,
and generally Arctic and temperate in range. For some reason or other the
late Dr. Gray placed _Halichoerus_ in the same sub-family with the Walrus!
_Phoca_ is not only marine, but is found in the Caspian and in Lake Baikal.
Their existence in those inland seas is believed to be a vestige of a
former connexion with the sea. _Halichoerus grypus_ is a large seal 8 feet
in length when full grown. Its colour is yellowish grey, with darker grey
spots and blotches. It is not uncommon on the shores of our islands,
particularly of the Hebrides and Argyllshire. The commonest Seal is _Phoca
vitulina_, not more than 4 to 5 feet long, and of the same spotted
coloration as the last. This Seal has, however, a much wider distribution,
being Arctic as well as British, American, and North Pacific. A curious
fact about this Seal is that it is not impatient of fresh water; not only
will it ascend rivers, but it will live in inland lakes. It is said to be
especially sensitive to musical sounds. _P. hispida_ is British, but a rare
visitor to our islands. It is essentially an Arctic species. The Harp Seal,
_P. groenlandica_, is so called on account of a harp-shaped black bar in
the males, which starts at {453} the shoulders and extends to the thighs.
Like the other Seals mentioned, the young are white when first born. As may
be inferred from its scientific name this species is also Arctic in range.
It is also a rare visitor to these shores.

The genus _Cystophora_ is the only other genus of which there is a British
representative. It is called the Hooded Seal on account of an inflatable
sac upon the face, with which it is said to attempt to terrify its enemies.
The genus has an incisor less in each half of each jaw than _Phoca_ and
_Halichoerus_. Its formula is I 2/1 while these genera are both 3/2. _C.
cristata_ is a large species reaching a length of 10 feet. The colour of
the back is dark grey with deeper coloured spots. A few individuals only
have been recorded from our coasts.

_Stenorhynchus_ ( = _Ogmorhinus_) is an Antarctic genus. The hind-feet are
clawless. The incisors are 2/2. The molars have an additional cusp, _i.e._
three in all.

The genus _Leptonyx_ with but one species, _L. weddelli_, is purely
Antarctic in range. Like the last genus it has two incisors, and has but
rudimentary claws upon the hind-feet; the first and fifth toes moreover are
the longest. The genus chiefly differs from the last in the simple conical
crowns of the molars, which have not the additional cusps of
_Stenorhynchus_.

_Ommatophoca_ is another Antarctic genus with but a single species, _O.
rossi_. In this genus the hind-feet have no claws, and the first and fifth
toes are longer than the others. The claws of the fore-feet are
rudimentary. The immense size of the orbits gives the name to the genus.
There are two incisors, and the molars are all very small.

_Monachus_ is a northern genus inhabiting the Mediterranean and the
Atlantic in the vicinity of Madeira and the Canary Islands. It has
rudimentary nails upon both pairs of feet. The first and fifth toe of the
hind-feet are longer than the others. As with the preceding genera, the
incisors are two in each jaw. The species are _M. albiventer_, the
Monk-Seal, and _M. tropicalis_, the Jamaica Seal.

Allied to _Cystophora_ is the genus _Macrorhinus_, with (possibly) two
species, of which one is Antarctic, the other frequents or frequented the
coast of California. The incisors are two in the upper jaw, and but one in
the lower. The premolars are four and the molar one; all the teeth are
small and simple, but {454} have long roots. The nose of the male has a
dilatable proboscis. The southern Elephant Seal is _M. leoninus_, and
reaches a length of some 20 feet. It occurs on the shores of Kerguelen and
some other more or less remote islands. Its habits have been studied and
described by several observers, beginning with Anson in the last century.
The late Professor Moseley gave a good account of this marine monster in
his book on the voyage of the "Challenger." When the animal is enraged, the
end of the snout is dilated; but when this happens there is no long and
hanging proboscis such as has sometimes been described. The inflation
affects the skin on the top of the snout, which thus rises rather upwards
during inflation. The inflated region, according to Mr. Vallentin, quoted
by Mr. J. T. Cunningham, is about 1 foot long in an individual of 17 feet.
It has been stated that this proboscis is a temporary structure, only
appearing in the breeding season; but recent observations have shown that
this statement is inaccurate; it persists all the year round. The males
fight greatly during the breeding season, and produce a roar which has been
compared to the "noise made by a man when gargling." The females and the
young males bellow like a bull. The males fight of course with their teeth,
literally falling upon one another with their whole weight. Mr. Cunningham
thinks that the use of the proboscis is to protect the nose from injury; or
that it may be merely the result of "emotional excitement." In any case the
Bladder-nosed Seal, _Cystophora_, is undoubtedly protected from injury by
the possession of a corresponding hood. The nose is the most vulnerable
place, and the existence of this hood would stave off the effects of a blow
in that region. Moseley, however, has said of _Macrorhinus_ that it cannot
be stunned by blows on the nose as other Seals can; but he attributes this,
not to the dilated snout, but to the bony crest on the skull, and to the
strength of the bones about the nose. This Seal crawls with difficulty on
the land, and as the animals move "the vast body trembles like a great bag
of jelly, owing to the mass of blubber by which the whole animal is
invested, and which is as thick as it is in a whale."[324] When lying on
the shore, these animals scrape sand and throw it over themselves,
apparently to prevent themselves from being {455} incommoded by the direct
rays of the sun, to the effects of which they are very susceptible. The
Elephant Seal is mild and inoffensive, unless enraged, and, of course,
during the breeding season.

ORDER VIII. CREODONTA.

This entirely extinct group of Mammalia may be thus characterised:--Small
to large carnivorous mammals, with skull on the whole like that of the
Carnivora and with trenchant teeth; digits with unguiculate phalanges; tail
long; extremities usually with five, sometimes with four digits. In the
carpus a centrale is present, and the scaphoid and lunar are separate.
Interlocking of posterior dorsal and lumbar zygapophyses very perfect.
Brain small but convoluted.

This group, which corresponds with the CARNIVORA PRIMIGENIA of Mr.
Lydekker, is not easy to separate absolutely from the existing and more
especially from some of the extinct members of the CARNIVORA VERA. They
also come exceedingly near the Condylarthra, the presumed ancestors of the
Ungulata, and like them begin in the earliest Tertiary deposits. Their
likeness to the carnivorous Marsupials has also been insisted upon; but it
would seem that the succession of teeth in the Creodonta is typically
Eutherian.

The characteristics of the group may be exemplified by an account of the
genus _Hyaenodon_, after which some of the more important deviations in
structure shown by other genera will be referred to.

_Hyaenodon_ is both American and European, and ranges through the Eocene
and the Upper Miocene. It is a much-specialised Creodont, and therefore
exhibits well the distinctive characters of the group. About a dozen
species have been described. One of the best-known is the American _H.
cruentus_, and the following description refers to it. The back part of the
skull is low and broad, and is compared by Professor Scott (who has
described this and other species) as being "somewhat like that of an
opossum."[325] The whole skull is {456} long, and the top has a great
sagittal crest. The paroccipital processes are short and are closely
applied to the mastoid processes. The mesethmoid is larger than in the
carnivorous Marsupials, and the frontals are very large. The palate has a
peculiar structure; in most species the hinder ends of the palatines are
separated by a narrow fissure which broadens gradually, thus forming the
posterior nares. In _H. leptocephalus_ the posterior nares are brought very
far back by the meeting of the alisphenoids. The presphenoid, contrary to
what we find in the Dog, for example, is chiefly concealed by the vomer,
which covers it. The mandible has a long and strong symphysis, and its
angle is not inflected. The fore-limb is described as being "weak when
compared with the modern Carnivora." The scaphoid and lunar are separate,
and there is a centrale. The teeth present us with nearly the typical
formula. There is only one molar missing in the upper jaw. The canines are
enlarged. It has been suggested from a consideration of its palate that
_Hyaenodon_ was a semiaquatic animal; the deep cleaving at the extremities
of the phalanges seems to point in the same direction, since they resemble
in this the genus _Patriofelis_, which there are other reasons to regard as
aquatic. This latter genus has a fore-limb which is very like that of the
Pinnipedia, the digits are much spread out, and would seem to have
supported a kind of paddle. In any case it certainly fed upon aquatic
tortoises, for their remains have been found in its coprolites. The name
_Limnofelis_, also applied to what appear to have been members of this
genus, is suggestive of their habits. _Patriofelis_, at least one species,
seems to have been of about the size of a Lion.

_Mesonyx_ has a brain case which is actually smaller than that of the
Marsupial _Thylacinus_. The lachrymal bone is very large, and extends a
little way over the face, as is also the case with _Hyaenodon_; this
condition is also found in Insectivora and in _Thylacinus_. The axis
vertebra has a curiously-shaped spine, which is very different from the
hatchet-shaped process of that vertebra usual in the Carnivora, but is not
unlike what exists in the Arctoid genera _Meles_ and _Mydaus_. The limbs
show much disparity in length, and seem to argue a much-arched back when
the creature progressed. The carpus is stated to be strikingly like that of
the Insectivora. There is as in other Creodonts a separation between the
scaphoid and lunar; {457} the centrale appears to be present. The pelvis
"is most like that of the bear," the metacarpals and the tibia, and some
other bones, resemble those of the Hyaena. In fact this animal shows those
combined characters which are common in archaic forms.

       *       *       *       *       *


{458}

CHAPTER XV

RODENTIA--TILLODONTIA

ORDER IX. RODENTIA[326]

Small to moderately large animals, furry, sometimes with spines. Toes with
nails of a claw-like character, or sometimes approaching hoofs. Usually
plantigrade, and only occasionally and partly carnivorous. Canine teeth
absent; incisors long and strong, growing from persistent pulps, and with
enamel only or chiefly on the anterior face, producing a chisel-shaped
edge; molars few (two to six), separated from the incisors by a wide
diastema. Caecum (nearly always present) very large, and often complicated
in structure. Brain, if not smooth, with few furrows, the hemispheres not
overlapping the cerebellum. Surface of skull rather flat; orbits not
separated from temporal fossae; malar bone in middle of zygomatic arch;
palate very narrow, with elongated incisive foramina; articular surface for
lower jaw antero-posteriorly elongated. Clavicles generally present. Testes
generally abdominal. Placenta deciduate, and discoidal in form.

The Rodents are a very large assemblage of usually small, sometimes quite
minute, creatures, embracing an enormous number of living generic types.
They are distributed all over the world, including the Australian region,
and, being small and often nocturnal, and by no means particular in their
diet, have managed to thrive and multiply to a greater extent than any
other group of living mammals. They are chiefly terrestrial creatures, and
often burrow or live in ready-made burrows. {459} Some, however, such as
the Voles, are aquatic; others, _e.g._ the Squirrels, are arboreal, and
there are "flying" Rodents exemplified by the genus _Anomalurus_. Their
range of habitat is in fact as wide as that of any other Order of mammals,
and wider than that of most.

[Illustration]

FIG. 231.--Side view of skull of Cape Jumping Hare (_Pedetes caffer_). ×
3/5. _AS_, Alisphenoid; _Ex.O_, exoccipital; _Fr_, frontal; _L_, lachrymal;
_Ma_, malar; _Mx_, maxilla; _Na_, nasal; _OS_, orbito-sphenoid; _Pa_,
parietal; _Per_ points to the large supratympanic or mastoid bulla; _PMx_,
premaxilla; _Sq_, squamosal; _Ty_, tympanic. (From Flower's _Osteology_.)

The most distinct anatomical characteristic of the Rodents concerns the
teeth. They are without exception entirely deprived of canines. Thus there
is a long diastema between the incisors and the molars. Another peculiarity
is, that in many cases the dentition is absolutely monophyodont. In such
forms as the Muridae there seems to be no milk dentition at all. In that
family there are only three molars; but in other types where there are
four, five, or six molars, the first one, two, or three, as the case may
be, have milk predecessors, and may thus be termed premolars. This has been
definitely proved to be the case in the common Rabbit, which has the
unusually large number of six grinding teeth in each half of the upper jaw
when adult. The first three of these have milk forerunners. On the other
hand the existence of four molars does not apparently always argue that the
first is a premolar; for Sir W. Flower found that in _Hydrochoerus_,[327]
none of the teeth had any forerunners, at any rate so far as could be
detected from the examination of a very young animal. The Rabbit appears to
be also exceptional, in that the second incisor of the upper jaw and the
incisor of the lower jaw have milk forerunners. In any case the tendency
towards monophyodontism is peculiarly well-marked in this group of mammals.
The incisors of Rodents are as a rule in each jaw a single pair of long and
strong teeth, which grow from persistent pulps, and {460} grow to a very
great length, extending back within the jaw to near the hinder part of the
skull. These teeth are reinforced in the upper jaw by a small second pair
in the Lagomorpha only. The incisors are chisel-shaped, and often brown or
yellow upon the outer face, as is the case also with some Insectivores.
This peculiar shape, and their strength, renders them especially capable of
the gnawing action which characterises the Rodents. It has been pointed out
that where the incisors are wider than thick, the gnawing powers are feebly
developed; and that on the contrary, where these teeth are thicker than
wide, the animals are good gnawers. The incisors have often an anterior
groove, or it may be grooves.

[Illustration]

FIG. 232.--Molar teeth of Rodents. A, of Capybara (_Hydrochoerus_); B, of
Squirrel (_Sciurus_); C, of _Ctenodactylus_. (After Tullberg.)

The cheek teeth vary in number from two (_Hydromys_) to six (Rabbit) on
each side of the two jaws. Four is the prevailing number outside the large
division of the Rat-like Rodents. They are often set at an angle to the
horizontal plane of the jaw, looking outwards and obliquely to its
longitudinal axis; the individual teeth too are not unfrequently bowed in
form, reminding us of those of _Toxodon_. This of course only occurs in
those genera which have hypselodont teeth. The pattern of the teeth varies
much, and the different forms recall the teeth of more than one other group
of mammals. They are either bunodont or lophodont. In many cases the tooth
is encircled with a ridge of enamel, which is either almost simple or has a
more complicated contour; such teeth are by no means unsuggestive of the
Toxodonts. Some of the lophodont molars are by no means unlike those of the
Proboscidea. In _Sciurus vulgaris_ the {461} encircling ridge is broken up
into tubercles, which gives to the tooth a striking likeness to those of
_Ornithorhynchus_. Other genera have teeth like those of many Ungulates. It
has been shown by Sir J. Tomes[328] that the minute structure of the enamel
differs in different groups of Rodents.

The skull shows certain primitive characters. In the first place there is
no distinction between the orbital and the temporal fossa.[329] The sutures
between the bones retain their distinctness for very long. Other
characteristic features are the following:--The nasals are large, and so
are the paroccipital processes. The palate in front of the molars is not
distinct from the sides of the skull, its edge gradually becoming rounded
off above. It is also very narrow. The premaxillae are large in relation to
the great incisors. There is often a very much enlarged infra-orbital
foramen through which passes a part of the masseter muscle. The jugal bone
lies in the middle of the zygomatic arch, which is complete and enormously
enlarged in the Spotted Cavy (_Coelogenys paca_). As in many Marsupials,
the jugal bone sometimes extends backwards to the glenoid cavity, where the
lower jaw articulates. It is usually said with an absolute want of accuracy
that the cerebral hemispheres of the Rodents are smooth and without
convolutions. This error has been repeated again and again in text-books.
As a matter of fact the cerebral hemispheres of many forms are quite well
convoluted,[330] the degree of furrowing corresponding, as in so many
groups of mammals, with the size of the animal. This at any rate is
generally true, though the large Beaver with its scant convolutions is an
exception. The smaller forms, such as _Mus_, _Sciurus_, _Dipus_, and
_Cricetus_ are quite smooth-brained. The best furrowed brain of any Rodent
which has been examined is that of the huge _Hydrochoerus_. The Sylvian
fissure is very generally not pronounced; but is particularly well-marked
in _Lagostomus_. In all, or in most, Rodents the hemispheres are separated
by an interval from the cerebellum, the optic lobes being visible between
the two.

The mouth cavity of this group of mammals is divided into two chambers by a
hairy ingrowth behind the incisors; this arrangement is useful for animals
which use their strong incisors {462} as gnawing and excavating tools as
well as for the purposes of alimentation; for it allows of substances being
gnawed away without the products of the chisel-like action being taken into
the hinder cavity of the mouth. The Rodents have for the most part a simple
stomach of normal form; but in a few this is complicated by a marked
constriction, which divides the cardiac from the pyloric portions. The
Hamster, for example, is thus characterised. In all the members of the
order, with the exception of the Dormice and some allied forms, the caecum
is large and often sacculated. In some forms (e.g. _Arvicola_, _Myodes_,
_Cuniculus_) the large intestine is coiled upon itself in a spiral way--a
state of affairs strongly suggestive of Ruminants.

The Rodents are primarily divisible into two great groups, the
Simplicidentata and the Duplicidentata, characterised mainly by the upper
incisor teeth. In the former there is but one pair of these teeth; in the
latter a second smaller pair lie behind the former.

SUB-ORDER 1. SIMPLICIDENTATA.

SECTION 1. SCIUROMORPHA.

The Anomaluri are separated by Thomas and others from this section as an
equal section, while by Tullberg they are grouped with _Pedetes_.

FAM. 1. ANOMALURIDAE.--The genus _Anomalurus_ suggests at first sight the
Flying Squirrels of Asia, _Pteromys_. It is, however, an entirely African
genus, and is to be distinguished from the Asiatic Rodents by a series of
scales at the root of the tail, imbricated, keeled, and forming possibly a
"climbing organ." This character serves also to distinguish the present
genus from _Sciuropterus_. The cartilage, moreover, which supports the
patagium springs from the elbow. There are four molars in each half of each
jaw. The eyes and ears are large. There are five fingers and toes, but the
thumb is small, though provided with a nail. The sternum has seven joints,
and nine ribs reach it. The clavicle is strong. Huet, who has recently
monographed the genus,[331] allows six species. The species vary in size.
{463}

_Anomalurus peli_ appears, according to Mr. W. H. Adams,[332] to be a
common species on the Gold Coast; it is coloured black and white, but in
spite of the warning which this colour should convey, is considered by the
perhaps rather omnivorous native as "the greatest delicacy." The animal is
nocturnal, but affects only bright moonlight nights. Their "flying"
consists of a jump from a high branch to a lower one, after which they
reascend the tree to a point of vantage for another jump. They are said to
feed upon nuts; but Tullberg only found the remains of leaves in the
stomach.

_Idiurus_ is a lately-described genus allied to _Anomalurus_. There are at
any rate two species, _I. zenkeri_ and _I. macrotis_. The thumb is more
reduced than in _Anomalurus_, and the fibula, contrary to what is found in
that genus and in most Sciuromorphs, is fused with the tibia below.

A third genus, very recently described and allied to both the foregoing, is
_Aëthurus_. It is a native of the French Congo,[333] and differs by the
absence of flying membranes. It has, however, the pad of large scales.
There is but one species, _A. glirinus_. It has a black bushy tail. The
postorbital processes of the frontals are totally wanting--there are not
even the traces to be seen in _Anomalurus_. The thumb has vanished. If we
are to compare _Anomalurus_ with the Squirrels then, thinks Mr. de Winton,
the present genus is probably diurnal by reason of the want of flying
membranes.

FAM. 2. SCIURIDAE.--The Squirrels, genus _Sciurus_, are world-wide in
range, the Australian region and the island of Madagascar being alone
excepted.

The eyes and the ears are large; the tail is of course long and bushy. The
fore-feet have an inconspicuous thumb; the hind-feet have four toes. The
soles of the fore-feet are naked or furry, those of the hind-feet are
hairy. There are twelve or thirteen dorsal vertebrae, and in correspondence
seven or six lumbars. The caudal vertebrae may be as many as twenty-five.
In the skull the frontals are broad, and there are long {464} postorbital
processes. The infra-orbital foramen is, as a rule, not large, but is
increased in size in a few forms. The number of separate pieces of bone in
the sternum is five. The molars of the upper jaw are five, but the first is
very small and soon drops out.

The Squirrels are often rather brilliantly coloured. The Chinese _Sc.
castaneiventris_ has grey fur with a rich chestnut-coloured under surface.
The Malabar Squirrel, _Sc. maximus_, as its name implies, a large animal,
has a deep reddish or chestnut-coloured fur above, which becomes yellow
below. The "Common Squirrel," "the lytill squerell full of besynesse,"
which is the Squirrel of this country, is brownish red on the upper parts
and white below. It ranges from this country as far east as Japan. Like
many other Rodents the Squirrel likes animal food and will eat both eggs
and young birds. "Camel's hair" brushes are made from this animal. The
genus _Tamias_, almost exclusively North American in range, is included by
Dr. Forsyth Major[334] in this genus, which then consists of considerably
over one hundred species.

The Ethiopian Ground Squirrels, genus _Xerus_, have a more elongated skull
than _Sciurus_, and the postorbital processes are shorter. The feet are not
hairy.

_Nannosciurus_ forms a perfectly distinct genus of Squirrels. These "Pygmy
Squirrels" differ in possessing a very elongated "face" and in the very
broad frontal region. The teeth are unlike those of _Sciurus_ in certain
features, and have been especially compared by Forsyth Major to those of
the Dormice. Four species of this genus are Malayan; one is West African.

The Bornean _Rheithrosciurus macrotis_ is the only species of its genus.
The genus may be distinguished by the exceedingly brachyodont molars, this
feature being more marked in this genus than in all other Squirrels. It is
called the "Groove-toothed Squirrel," from the "seven to ten minute
parallel vertical grooves running down the front face of its
incisors."[335]

The genus _Spermophilus_ includes a large number (forty or so) of
Palaearctic and Nearctic animals known as Sousliks. The ears are small;
there are cheek pouches as in _Tamias_. The general aspect of the animal is
like that of a Marmot, and they bridge over the exceedingly narrow gap
which separates the Marmots from the true Squirrels. Anatomically the skull
is like that of {465} _Arctomys_; the molars are five in the upper and four
in the lower jaw. The caecum is relatively speaking very small; the
measurements in a specimen of _S. tredecimlineatus_, dissected by Dr.
Tullberg, were: small intestine, 580 mm.; large intestine, 170 mm.; and
caecum, 27 mm. In _Tamias_ also the caecum is not greatly developed. These
animals are burrowing in habit.

The Prairie-dogs, genus _Cynomys_, of which the best-known species is
perhaps _C. ludovicianus_, are very like the Squirrels, but they are not
arboreal creatures; they live in burrows on the ground, as their vernacular
name denotes. The genus is entirely North American, and four species have
been differentiated.

The Prairie-dog or Prairie-marmot is some 10 inches to one foot in length.
The tail is no more than 2 inches. The ears are very small; the thumb is
fully developed and bears a claw. The measurements of the various sections
of the intestine are the following:--Small intestine, 860 mm.; large
intestine, 690 mm.; caecum, 75 mm. Thus the caecum is not large
comparatively speaking. These animals dig burrows on grassy plains which
they share with the Ground Owl (_Speotyto cunicularis_) and with
Rattlesnakes, all three species appearing to live in perfect amity.
Probably the Owls use the conveniently-constructed burrows, and the
Rattlesnakes come there to look after the young of both.

[Illustration]

FIG. 233.--Long-tailed Marmot. _Arctomys caudatus._ × 1/7.

Closely allied to the last are the Marmots, genus _Arctomys_. They differ
in the rudimentary character of the thumb and in the longer tail. The eyes
and ears are small. The distribution of the genus is Nearctic and
Palaearctic. There are ten species of {466} the genus. The Alpine Marmot,
_A. marmotta_, is familiar to most persons. The animal lives high up in the
Alps, and when danger threatens it gives vent to a shrill whistle. It
hibernates in the winter, and as many as ten to fifteen animals may be
found closely packed together in a single, carefully-lined burrow.

The only other European species is _A. bobac_, the Siberian Marmot, which
occurs in the extreme east of Europe, and is also Asiatic. There are four
North American species, including the Quebec Marmot, _A. monax_.

[Illustration]

FIG. 234.--Flying Squirrel. _Pteromys alborufus._ × 1/5.

The genus _Pteromys_ (of which the proper name, antedating _Pteromys_ by
five years, appears to be _Petaurista_) is confined to the Oriental region,
where there are a dozen species or so. The limbs are united by a parachute
extending to the toes, and supported anteriorly by a cartilage attached to
the wrists. There are also membranes anteriorly uniting the fore-limbs to
the neck, and posteriorly uniting the hind-limbs to the root of the tail
and a trifle beyond. The skull and the dental formula are as in Sciurus,
but the pattern of the molars, which is much complicated, seems to argue a
different mode of nutrition. There are twelve pairs of ribs. The large
intestine (in _P. petaurista_) is very nearly as long as the small, and the
caecum is also "colossal"; the measurements in an individual of the species
named were: small intestine, 670 mm.; caecum, 320 mm.; large intestine, 650
mm. {467} The caecum is disposed in a spiral. The teats are three pairs,
non-inguinal in position.

The size of these squirrels is 16 to 18 inches exclusive of the tail, which
is longer. These animals can make an exceedingly long jump with the help of
their flying membrane. Nearly eighty yards is the longest distance given
for these aerial excursions. It is stated that they are able to steer
themselves to some extent while in the air. As appears to be the case with
so many Rodents, these animals feed largely upon beetles and other insects,
besides bark, nuts, etc.

The allied genus _Sciuropterus_ has a much wider range. It extends into the
Palaearctic region and into North America, besides being found in India.
There is here no membrane reaching to the tail. The palms and soles are
furry. The caecum is very much shorter, and so is the large intestine. The
latter, in _S. volucella_, is not more than one-third of the length of the
small intestine. In other features there are no remarkable differences in
structure, save that the mammae, always three pairs, may be inguinal.

Of the genus _Eupetaurus_[336] but a single species is known, which is
limited to high altitudes at Gilgit and perhaps in Thibet. Its principal
difference from the other genera of Flying Squirrels is that the molars are
hypselodont instead of brachyodont. The interfemoral membrane is
rudimentary or wanting. The one species is _E. cinereus_. It is thought to
live "on rocks, perhaps among precipices." Dr. Tullberg attributes the
hypselodont teeth to the fact that the mosses upon which it is believed to
feed may have much sand and earth intermingled, which would naturally lead
to a more rapid wearing away of the teeth, and hence a need for a good
supply of dental tissue to meet this destruction.

FAM. 3. CASTORIDAE.--This, the third family of the Sciuromorpha, contains
but one genus, _Castor_, the Beaver, with at most two species, one North
American, the other European. This large Rodent has small eyes and ears, as
befits an aquatic animal, and the tail is exceedingly broad and covered
with scales; the transverse processes of the caudal vertebrae, in order
better to support the thick tissues lying outside them, are divided in the
middle of the series into two. The hind-feet are much larger than the
fore-feet, and are more webbed than in any other aquatic Rodent. {468}

In the skull the infraorbital foramen is small as in Squirrels. The
postorbital process has practically vanished. The four molars stand out
laterally from the jaws. The incisors, as might be surmised from the
habits, are particularly strong. The stomach has near the entrance of the
oesophagus a glandular patch, which seems to be like that of the Wombat
(see p. 144). In both sexes the cloaca is very distinct and comparatively
deep.

The two species of the genus are _C. canadensis_ and _C. fiber_. The latter
is of course the European species, which is now found in several of the
large rivers of Europe, such as the Danube and the Rhone. But it is
everywhere getting scarce, and limited to quite small and isolated
colonies.

In this country it is absolutely extinct and has been since before the
historic period. There is apparently no documentary evidence of its
survival down to this period. But the numerous names of places which are
called from this animal illustrate its former prevalence. Examples of such
names are Beverley in Yorkshire, and Barbourne or Beaverbourne in
Worcestershire. In Wales, however, Beavers seem to have persisted longer.
But they were rare in the Principality for a hundred years or so before the
Norman Conquest. The king Howel Dda, who died in 948 A.D., fixed the price
of a Beaver skin at 120 pence, the skins of Stag, Wolf, and Fox being worth
only 8 pence apiece. The Beaver was called by the Welsh "Llost-llyddan,"
which means "broad-tail." Its existence in the country is handed down in
the name of Llyn-ar-afange, which means Beaver lake. The last positive
record of the Beaver in Wales seems to be the statement of Giraldus
Cambrensis that in 1188 the animal was still to be found in the river Teivy
in Cardiganshire. In Scotland the Beaver is said to have continued down to
a later date. Ireland it never reached. The remains of this animal by their
abundance show the former prevalence of _C. fiber_ in this country. It is
known from the fens of Cambridgeshire, and from superficial deposits
elsewhere. The Thames formerly had its Beavers, and apparently it was
widely spread through the country generally.

The Beaver not only furnishes collars and cuffs for coats; it was used, as
every one knows, to provide hats. But the usefulness of the animal by no
means ended here in the eyes of our {469} forefathers. The Rev. Edward
Topsell observed that "for giving great ease unto the gowt the skinnes of
beavers burned with drie oynions" are excellent. Castorein as a drug, if
not in actual use, has quite recently been a part of the pharmacopoeia. It
is derived from the anal glands common to this and other Rodents, and
indeed many other mammals.

A large extinct form of Beaver is _Trogontherium_,[337] found in the
"Forest-bed" of Cromer. The skull is about one-fourth longer than that of
_Castor_. It has a less inflated bulla, and slightly more pronounced
postorbital processes than _Castor_. The third molar (fourth grinding
tooth) is relatively larger than in _Castor_, and has a rather more folded
crown. The foramen magnum is more triangular.

FAM. 4. HAPLODONTIDAE.--A separate family seems to be required for the
genus _Haplodon_, whose characters will therefore be merged with those of
its family. It is to be distinguished from most other Squirrel-like
creatures by the fact that there is no postorbital process to the frontal.
The molar teeth are five in the upper and four in the lower jaw. The
Sewellel, _H. rufus_, like the other species of the genus (_H. major_), is
found in North America west of the Rocky Mountains. It has the habit of the
Prairie-marmot, and has a short tail, only moderately long ears, and
five-toed feet. Tullberg is of opinion that this animal nearly represents
the ancestral form of the Squirrel tribe.

SECTION 2. MYOMORPHA.

This subdivision of the Rodents contains, according to Mr. Thomas's recent
estimate,[338] no less than 102 genera. It is therefore obviously
impossible to do more than refer to some of the more interesting of these.
This group is again divided into the following families:--

(1) Gliridae, including the Dormice.

(2) Muridae, the Rats, Mice, Gerbilles, Australian Water-rats, Hamster.

(3) Bathyergidae, Cape Mole, etc.

(4) Spalacidae, Bamboo Rats. {470}

(5) Geomyidae, Pouched Rats.

(6) Heteromyidae, Kangaroo Rats.

(7) Dipodidae, Jerboas.

(8) Pedetidae.

The Gliridae have no caecum, so usual in the Rodentia. It is true that all
the genera have not been dissected, but it is known that in the true
Dormice, as well as in the genus _Platacanthomys_, a caecum is absent.

Apart from these few exceptions the Mouse-like Rodents all possess a
caecum, though it is often not very large. They are all smallish animals,
and are modified to a great variety of habit and habitat. There are
burrowing, swimming, and climbing forms. The group is universal in range,
even including the Australian region, in which they are the only Rodents.

FAM. 1. GLIRIDAE.--This family, also called Myoxidae,[339] includes the
Dormice, and is entirely an Old-World family, absent only from the Malagasy
region. Its most important differential character is the total absence of
the caecum and of any sharp boundary between the small and large intestine.
The molars are usually four. The eyes and ears are well developed.

The genus _Muscardinus_ includes only the Common Dormouse, _M.
arellanarius_. This small creature, 3 inches long with a tail of 2½ inches,
is, of course, a well-known inhabitant of this country. It is also found
all over Europe. It is not particularly abundant in this country, and a
good specimen is said to be worth half a guinea. As the specific name
denotes, it lives largely on hazel nuts; but it will also suck eggs and
devour insects. The animal makes a "nest" in the form of a hollow ball. Its
hibernation is well known, and has also given rise to the German name
("Schläfer") of the group. It was well known to Aristotle, who gave or
adopted the name [Greek: Eleios] for the animal. Its winter
sleep--suggestive of death--and its revivification in the spring gave the
Bishop of Salamis, Epiphanius, an argument for the resurrection of man. The
fur was reckoned in Pliny's time a remedy for paralysis and also for
disease of the ears.

The genus _Myoxus_ includes also but a single species, _M. glis_, the
so-called "Fat Dormouse" of the Continent. It has no {471} glandular
swelling at the base of the oesophagus, such as occurs in the last genus
and in _Graphiurus_. Of _Graphiurus_ there are thirteen species, all
African in range. The genus does not differ widely from the last. There is,
however, a glandular region of the oesophagus. _Eliomys_ is the last genus
of typical Dormice. It is Palaearctic in range.

_Platacanthomys_, of a Dormouse-like form, has like other Dormice a long
tail, on which the long coarse hairs are arranged in two rows on opposite
sides towards the tip; it is represented by a single species, _P.
lasiurus_, from the Malabar coast. It is arboreal in habit. The fur is
mingled with flattened spines. The molars are reduced to three on each side
of each jaw. This form has been bandied about between the "Mice" and the
"Dormice"; but Mr. Thomas's discovery of the absence of the caecum argues
strongly in favour of its correct location among the Gliridae. _Typhlomys_
is an allied genus, also from the Oriental region. This and the last are
placed in a special sub-family of the Gliridae, Platacanthomyinae, by Mr.
Thomas.

FAM. 2. MURIDAE.--This family, that of the Rats and Mice in a wide sense,
is the most extensive family of Rodents. In it Mr. Thomas includes no less
than seventy-six genera. The molars are generally three. The tail is fairly
long, or very long, and the soles of the feet are naked.

SUB-FAM. 1. MURINAE.--The true Rats and Mice may be considered to form a
sub-family, Murinae. The genus _Mus_, including the Rats and Mice in the
limited sense of the word, contains about 130 species. They are exclusively
Old World in range, being only absent from the Island of Madagascar. In the
New World there are no species of the restricted genus _Mus_. The eyes and
the ears are large; the pollex is rudimentary, and bears a nail instead of
a claw. The tail is largely scaly. All the members of the genus are small
animals, some quite minute. In this country there are five species[340] of
the genus, viz. the Harvest Mouse, _M. minutus_, which has a body only 2½
inches long with an equally long tail. It is the smallest of British
quadrupeds with the exception of the Lesser Shrew. The Wood Mouse, _M.
sylvaticus_, is about twice the size; it differs also from the last species
in that it {472} frequents barns, and is thus sometimes mistaken for the
Common Mouse, from which, however, it is to be distinguished by its
coloration and longer ears. The latter, _M. musculus_, is too familiar to
need much description. A curious variety of it has occurred. This has a
thickened and a folded skin like that of a Rhinoceros, and the hair has
disappeared. The Black Rat, _M. rattus_, is like a large Mouse, and is
smaller and blacker in colour than the "Hanoverian Rat." It is sometimes
called the "Old English Rat," but seems nevertheless to be not a truly
indigenous Rodent. It has been so defeated by competition with the
Hanoverian Rat that it is now not a common species in this country.

The Hanoverian or Brown Rat, _M. decumanus_, is a larger and a browner
animal than the last. It is very widely distributed through the globe, no
doubt largely on account of the fact that it is readily transported by man.
The same is the case with the Common Mouse, whose real origin must be a
matter of doubt. The original home of the Brown Eat is thought by Dr.
Blanford to be Mongolia. There is so far a justification for the name
"Hanoverian Rat" that the animal seems to have reached this country about
the year 1728. But there is no reason for calling it, as is sometimes done,
the Norway Rat.

Some members of this genus, whose fur is interspersed with spines, or which
are quite spiny, have been separated as a genus, _Leggada_, which, however,
is not generally allowed.

Closely allied again is _Chiruromys_, which has a strongly prehensile tail,
a feature which is not common among the Myomorpha, though _Dendromys_, a
tree-frequenting form, and _Mus minutus_, already spoken of, show the same
character. Many Mice seem to have prehensile tails, which they can curl
round branches; but it is not so fully developed as in the species just
named.

A number of other genera are referable to the true Mice, the sub-family
Murinae of Thomas's classification. The Syrian and African _Acomys_ has
very spiny fur, so much so that "when it has its spines erected it is
almost indistinguishable at the first glance from a diminutive hedgehog."
The genera _Cricetomys_, _Malacomys_, _Lophuromys_, _Saccostomus_,
_Dasymys_ are restricted to the Ethiopian region. _Nesokia_ is Oriental,
reaching {473} also the Palaearctic region. _Vandeleuria_, _Chiropodomys_,
_Batomys_, _Carpomys_ are Oriental, the last two being confined to the
Philippines.

Another peculiar Philippine genus is _Phlaeomys_, of large size, and allied
to it is _Crateromys_, originally confounded with it. _Batomys granti_ is
also confined to Luzon. Its molars are three, like those of the also
restricted and Philippine _Carpomys melanurus_, which is an arboreal form.
There is a second species, _C. phaeurus_.

_Phlaeomys_ is placed, however, by Mr. Thomas in a distinct sub-family of
its own, PHLAEOMYINAE, and is removed from the Murinae.

_Hapalomys_, with but one species, is Burmese. _Pithecochirus_ is Javanese
and Sumatran. _Conilurus_ (also known as _Hapalotis_) is a genus containing
species which are termed Jerboa Rats, on account of their mode of
progression. They are desert and Australian forms. There are sixteen
species.

[Illustration]

FIG. 235.--Spiny Mouse. _Acomys cahirinus._ × ½.

_Mastacomys_, with one species, is limited to Tasmania. _Uromys_, with some
eight species, is from Queensland, and inhabits also the Aru Islands and
the Solomon Islands. The Celebesian _Echiothrix_, or _Craurothrix_ as it
should apparently properly be called, is another genus containing but a
single species. _Golunda_ is both Oriental and Ethiopian, one species
occurring in each region. The beautiful little striped Barbary Mice,
_Arviacanthis_ (or _Isomys_), are African, north as well as tropical.

The genus _Saccostomus_ resembles the Hamsters in the presence of cheek
pouches. Its teeth, however, are Murine. It agrees with _Steatomys_ in the
comparatively short tail. The caecum is rather long. {474}

SUB-FAM. 2. HYDROMYINAE.--The genus _Hydromys_,[341] of which there are
several species, the best known being _H. chrysogaster_, is an exclusively
Australian form, and is aquatic in habit. It is a foot or so in length, and
has a fairly long tail. The fore- and hind-limbs are webbed, in
correspondence with its habits. The Australian Water-Rat is black, with an
admixture of golden-coloured hairs dorsally and golden colour below, with a
lighter median stripe. The thumb is small, and the webbing of the hands is
not so marked as is that of the feet. The molars are only two in each half
of each jaw. The caecum is rather small, the measurements of the alimentary
canal being: small intestine, 895 mm.; large intestine, 278 mm.; caecum, 70
mm. Allied to the last is _Xeromys_, a genus which is also Australian, but
limited to Queensland. It has been established by Mr. Thomas,[342] who
discovered that it has the same reduced formula as _Hydromys_. _Xeromys_,
however, is not an aquatic animal, and has unwebbed feet.

In the Luzon highlands Mr. Whitehead has discovered, and Mr. Thomas quite
recently described,[343] a number of peculiar Rodents. Of these the genera
_Chrotomys_, _Celaenomys_, and _Crunomys_ are allied to the Australian and
New Guinea _Hydromys_.

_Chrotomys whiteheadi_ is unusual among Muridae, in its coloration being
marked by a pale stripe down the back. The creature is the size of the
Black Rat (_Mus rattus_). It is terrestrial not aquatic in habit, in spite
of its likeness to _Hydromys_. The molars, however, are 3/3.

_Crunomys fallax_ is more like _Hydromys_. It has, however, three molars,
as in the last genus. But the skull has the flattened form characteristic
of _Hydromys_ as opposed to _Mus_.

Like _Batomys_, _Celaenomys silaceus_ is also somewhat intermediate between
_Hydromys_ and _Mus_. It is described as very Shrew-like in appearance, and
has a very pointed muzzle. Its habits Mr. Whitehead is "quite unable even
to guess at." Like _Hydromys_ and _Xeromys_ this Rodent has but two molars.

SUB-FAM. 3. RHYNCHOMYINAE.--The genus _Rhynchomys_, containing but one
species, _Rh. soricioides_ (of Thomas), is also, as both its generic and
specific names imply, a somewhat Shrew-like form in external aspect. The
skull, too, is Insectivore-like in its {475} elongation, and the lower
incisors are worn to needle-like points. The two molars are excessively
minute, and thus the always large gap in the jaws is greatly exaggerated.
It is suggested that this Rat is an insect-eater, but nothing positive is
known.

SUB-FAM. 4. GERBILLINAE.--The Gerbilles form another sub-family,
Gerbillinae, of the Muridae, or a family, according to some. The best-known
genus is _Gerbillus_, including the Gerbilles proper. These animals are Old
World in range, belonging to the three regions of that part of the world.
There are a large number of species in the genus, over thirty. They have a
Jerboa-like form, with rather long hind-limbs and a long and hairy tail.
But the hind- as well as the fore-feet are five-toed. The molar teeth have
no trace of tubercles, but only transverse lamellae of enamel. The incisors
are orange; they are white in _Dipus_. _Gerbillus pyramidum_ is 90 mm.
long, with a tail of 125 mm. The ears are long, 13 mm. The tail has longer
hairs at the tip.

[Illustration]

FIG. 236.--Gerbille. _Gerbillus aegyptius._ × ½.

_Psammomys_ is in some respects different. The tail is shorter than in
_Gerbillus_; its length in an individual of 165 mm. was 130 mm. As in
_Gerbillus_ there are four pairs of teats, two pectoral and two inguinal.
This genus is exclusively Palaearctic in range. _Meriones_ has a range
co-extensive with that of _Gerbillus_.

_Pachyuromys_ is an Ethiopian genus with a short tail. As the generic name
denotes, the tail is not only short but thick and fleshy.

SUB-FAM. 5. OTOMYINAE.--The allied genera, _Otomys_ and _Oreinomys_, are
Ethiopian. _Otomys unisulcatus_ has a tail shorter than the body, the
measurements of a female of this species being 137 mm. with a tail of 87
mm. The ear is long, whence the name; it measured in this specimen 20 mm.
{476}

SUB-FAM. 6. DENDROMYINAE.--The genus _Deomys_ is an African form,
consisting of only one species from the Congo region. _D. ferrugineus_ has
a reddish colour as its name implies; the soles are quite naked and the
tail is long and slender. It is considerably longer than the body,
measuring (minus a fragment of the tip) 172 mm., while the body is 125 mm.
long. The characters of the molar teeth, which are three, are intermediate
in their form between those of the true Rats and those of the Hamsters.

_Dendromys_ is also Ethiopian in range. There are several species. _D.
mesomelas_ is a smallish creature, 60 mm. long, with a tail of 90 mm.

_Steatomys_ is another African genus, allied to the last. Its tail,
however, is only half the length of the body. The two remaining genera are
_Malacothrix_ and _Limacomys_. Their range is African.

SUB-FAM. 7. LOPHIOMYINAE.--Allied to the Hamsters is the singular East
African genus _Lophiomys_, with only one species, _L. imhausi_, of
Milne-Edwards.[344] The size is between that of a Rabbit and of a
Guinea-pig. The stomach is curved and somewhat intestiniform. It has been
termed the Crested Rat on account of the "prominent crest of stiff hair
running down the back." The fingers and toes are five, and the very long
tail is clad with hair longer than that upon the body generally. The pollex
is rudimentary, and the hallux is opposable.

The most remarkable structural feature in this genus concerns the skull,
and on account of this it has been regarded as the type of a separate
family. The temporal fossa behind the eye is covered over by a complete
bony plate, formed by a downgrowth of the parietal, meeting an upgrowth
from the malar; this singular arrangement of the bones recalls the
conditions which obtain in turtles. The whole skull, moreover, is covered
with symmetrically disposed granulations, such as are found in no other
mammal; it suggests rather the skull of certain fish. It is believed that
the bony plate already referred to is not really a portion of the bones of
which it appears to be a prolongation, but merely an ossification of
fasciae in this region. The atlas is granulated like the skull; there are
sixteen pairs of ribs and a feeble clavicle. The molars are three, and of a
peculiar form. {477} They have, in the case of the first three, transverse
ridges, from which stand up two sharp and long tubercles. The other teeth
have two ridges. The incisors are pale yellow. The shape of the teeth and
the smallness of the caecum suggest that this Rodent is not so purely a
vegetarian as others, and that it nourishes itself largely upon insects.

SUB-FAM. 8. MICROTINAE.--The Voles or Water-Rats form a distinct group of
Murine animals, to which the sub-family name of Microtinae has been applied
from the genus _Microtus_ (more generally known as _Arvicola_), a genus
which includes the Water-Rat and Field-Voles of this country. This genus
has short ears, and a short and hairy tail. Its build is stouter and
clumsier than that of the Rats. The genus is confined to the Palaearctic
and the Nearctic regions. In this country there are three species. The best
known is the Water-Vole or Water-Rat, _M. amphibius_, which has been seen
by most people, and which frequents streams, ponds, and canals. The feet,
curiously enough, are not webbed, which seems to argue the recent adoption
of an aquatic life. Mr. Trevor-Battye has remarked that this animal, when
swimming at leisure, uses its hind-limbs only, carrying the fore pair at
the sides like a Seal. The Bank-Vole, _M. glareolus_, is rather a local
species in this country. It is a terrestrial Vole, and burrows. The
Field-Vole, _M. agrestis_, has become notorious on account of the
"plagues," to which its immense numbers have on occasions given rise. It is
the smallest species, and has a greyish-brown fur like the Water-Vole, the
Bank-Vole being redder. To give an idea of the cost of the depredations of
this animal, Mr. Scherren quotes[345] a farmer who gave evidence before the
Agricultural Commission to the effect that, putting the damage of one Vole
at two pence, the amount of loss suffered on a farm of 6500 acres in two
years would be £50,000!

The genus _Fiber_ comes very near the last. It is a North American genus.
The hind-feet are slightly webbed; the tail is a trifle shorter than the
body, and is compressed and scaly, with scattered hairs. The thumb is
short, but with a fully-developed claw. As in the last genus, the small and
large intestines are roughly of the same length, and the caecum is about
one-fourth of the length of either. It is known as the "Musquash." {478}

Of _Fiber zibethicus_, or rather a closely-allied form, _F. osoyoosensis_,
from Lake Osoyoos near the Rockies, Mr. Lord writes[346] that it constructs
for itself a house of bulrushes built up from the bottom in 3 or 4 feet of
water. It is dome-shaped, and rises about a foot out of the water. "If a
dead or badly-wounded duck be left on the pool, it is at once seized on,
towed into the house, and doomed." Thus it appears that this Rodent, like
so many others, is largely carnivorous. It has also been asserted that it
eats fish.

_Neofiber_ is an allied genus, North American in range. The species, _N.
alleni_, is compared, as regards outward form, with the Water-Vole, _M.
amphibius_. It has, however, a shorter tail.

Another very well-known member of this sub-family is the Lemming. The name,
however, applies to two quite distinct genera. The genus _Cuniculus_,
including the Banded Lemming, _C. torquatus_, is an inhabitant of North
America, Siberia, and Greenland. The tail is short, its length being 12 mm.
as against a body length of 101 mm. The feet are furred beneath, a not
unusual state of affairs in Arctic mammals. The ears are very slight. The
thumb is well developed, and bears a claw.

In _Myodes_, on the other hand, which is not so markedly an Arctic animal,
though occurring in both Palaearctic and Nearctic regions, the ears are
rather bigger, though still smaller than those of _Microtus_. The under
surfaces of the feet are similarly furred. The tail is also short. It is
commonly said that the two genera are to be distinguished by the furred
feet of _Cuniculus_, and by the absence of fur in the present genus. That,
according to Tullberg, does not appear to be the case. The differences are
thus so much reduced that it seems almost unnecessary to retain the two
genera. The best known species of _Myodes_ is of course the Scandinavian
Lemming, _M. lemmus_. This animal used to occur in this country in
Pleistocene times (as did also _C. torquatus_), and recently Dr. Gadow has
found remains with skins attached in caves in Portugal. It may still
survive in the mountains of the Peninsula.

The actual habitat of the Lemming in Scandinavia is the great tablelands,
3000 feet high in the centre. The migrations do not take place with
regularity; even twenty years may elapse before the appearance in
cultivated lands of those countless {479} hordes so familiar (as far as
their description is concerned) to everybody. The Lemmings do not return
from their exodus. They die from various causes, including combats with one
another. Their chief foes, however, are Wolves and Gluttons, Buzzards and
Ravens, Owls and Skuas, which batten on the migrant hordes. Their sudden
increase in numbers recalls the similar increase at times of the
Field-Vole, to which reference has already been made.

_Ellobius_ is an Old-World genus, which leads a "Talpine" life, and has in
consequence rudimentary external ears and very small eyes. The tail is
short. Contrary to what might be expected from its mode of life, the claws
upon the digits are not strong.

The remaining genera of Vole-like Murines are _Phenacomys_ and _Synaptomys_
from North America, and Siphneus from Palaearctic Asia. _Evotomys_ is one
of those genera which are common to both the Palaearctic and the Nearctic
regions, but the bulk of the species are North American.

SUB-FAM. 9. SIGMODONTINAE.--This is the name given to another sub-family of
Murine Rodents, a group which includes the Hamsters in the Old World as
well as a large number of South American genera of Rat-like animals. Of
these latter there are a very large number, the bulk of the group being
American.

The Hamsters, genus _Cricetus_, as it is usually called, although
apparently the correct name is Hamster, are Old-World forms of Pouched
Rats. The Common Hamster, _C. frumentarius_, is about 210 mm. long, with a
tail of 58 mm. It has cheek pouches. The small and the large intestines are
not very unequal in length, and the caecum is fairly large, being about
one-sixth to one-seventh of the length of either. It is a purely
vegetable-feeding creature, and in Germany where it occurs (and from which
language its vernacular name is derived), hibernates during the winter in
its burrow, having previously surrounded itself with a great accumulation
of food carried thither.

To North America are peculiar the genera _Onychomys_, _Sigmodon_, and
_Peromyscus_. The genus _Sigmodon_, the Cotton Rats, reaches Central
America, and even gets a little farther south. The other two genera, though
mainly North American, also extend their range to the south. _Onychomys_
has hairy {480} foot-pads, a state of affairs which characterises a number
of these Rodents.

The genera _Megalomys_, _Chilomys_, _Reithrodontomys_, _Eligmodontia_,
_Nectomys_, _Rhipidomys_, _Tylomys_, _Holochilus_, _Reithrodon_,
_Phyllotis_, _Scapteromys_, _Acodon_, _Oxymycterus_, _Ichthyomys_,
_Blarinomys_, _Notiomys_ are South American forms. _Oryzomys_ and
_Rheithrodontomys_ are common to both parts of the New World.

The genus _Ichthyomys_ is remarkable on account of its un-Rodent-like
habits and of certain associated structural changes. _I. stolzmanni_ was
obtained from Mount Chanchamays in Peru at an altitude of 3000 feet; it is
a habitual fish-eater, and lives in streams. Another species, _I.
hydrobates_, was formerly referred to _Habrothrix_. The skull shows
likenesses to that of the Australian _Hydromys_; but the most marked
characters of adaptation are those of the teeth and caecum. The cutting
edges of the upper incisors form a reversed [347] of obvious use in holding
a slippery fish. The caecum is much reduced, short, and narrow. The general
Otter-like shape of the creature is largely due to its flattened head,
though its "size and general proportions are much as in the common Black
Rat."[348]

This sub-family contains a number of genera from Madagascar, viz.
_Brachytarsomys_, _Nesomys_, _Hallomys_, _Brachyuromys_, _Hypogeomys_,
_Gymnuromys_, and _Eliurus_.

SUB-FAM. 10. NEOTOMINAE.--The last sub-family of the Muridae is that of the
Neotominae, containing the North American genera _Neotoma_, _Xenomys_,
_Hodomys_, and _Nelsonia_.

FAM. 3. BATHYERGIDAE.--This family contains several genera which consist of
subterranean forms. All these Rodents agree in a number of characters, of
which the principal are as follows:--

The eyes are very small, and the external ears are reduced to the merest
fringe of skin round the aural aperture. The legs are short, as is the
tail; the hair-covering is reduced--a reduction which finds its culmination
in the nearly nude _Heterocephalus_. Being burrowing creatures, a number of
other modifications in accordance with this mode of life are to be seen in
their structure. The upper incisors stand out in front of the closed lips,
and prevent the entrance of earth. For the same reason {481} the nostrils
are small, and the forehead but little expanded between them.

The genus _Bathyergus_ contains but a single species, the Cape Mole-Rat,
which is found in Southern Africa; it is of moderate size, not exceeding a
small Rabbit in dimensions. On the fore-limbs are exceedingly long claws,
of which that borne by the second finger is the longest, and the claw of
the thumb the shortest. The hind-feet have by no means such long claws. The
scratching and burrowing is naturally chiefly effected by the fore-limbs.
The small and large intestines are of equal length, and each is rather more
than six times the length of the caecum; in these measurements the present
genus differs from the next.

_Georhychus._--Of this African genus there are about ten species. The claws
are not so long as in the last genus, but there are, as in _Bathyergus_,
four molar teeth on each half of each jaw. The intestinal measurements in
an example of _G. capensis_ were: small intestine, 25 inches; caecum, 4
inches; large intestine, 15 inches.

The genus _Myoscalops_ or _Heliphohius_ (also with an African range) has
six back teeth on each side. A number of species sometimes referred to the
last genus are placed here by Mr. Thomas. The claws are small.

One of the most remarkable genera of this family is the little
_Heterocephalus_ from Abyssinia and Somaliland. As Mr. Thomas justly
remarks,[349] it "is a peculiar-looking little creature, about the size of
the Common Mouse, but looking almost more like a tiny hairless puppy on
account of its nearly naked skin, small eyes, and peculiar physiognomy."
Though apparently naked, there are numerous scattered hairs over the entire
body, and the toes are fringed with stiffish hairs, which must be
advantageous to a burrowing animal. There are two species, _H. glaber_
(originally described by Rüppell), and _H. phillipsii_, of which our
knowledge is due to Mr. Thomas. The length of the entire creature including
the tail is not more than 134 mm., both species being approximately of the
same dimensions. Mr. Lort Phillips, the discoverer of the species which
bears his name, writes "that this little creature, called 'Farumfer' by the
Somali, throws up in places groups of miniature craters, which exactly
resemble volcanoes in active eruption. When the little beasts were at {482}
work, I used frequently to watch them, and found that the loose earth from
their excavations was brought to the bottom of the crater, and sent with
great force into the air in a succession of rapid jerks, and that they
themselves never ventured forth from the shelter of the burrows."[350]

FAM. 4. SPALACIDAE.--"The Spalacidae," observes Dr. Blanford, "are
sometimes called rodent moles, and resemble a mole in general aspect,
having cylindrical bodies, short limbs, small eyes and ears, large claws,
and a short or rudimentary tail." The existence of a spiral valve in the
caecum may perhaps characterise this family; but it has at present only
been found in the two genera _Spalax_ and _Rhizomys_.

_Spalax_ has inconspicuous eyes and external ears. The tail is totally
absent. The lower incisors are more developed than in other Rodents; they
project in a bony sheath beyond the posterior end of the ramus of the lower
jaw. The scapula is long and narrow. The large intestine is half the length
of the small intestine. The animal seems to have only two pairs of teats,
one pectoral the other inguinal.

_Spalax typhlus_ of Egypt, which is probably not different from the
European form, makes extensive burrows, some of the branches being even 30
to 40 yards in length. In a "domical chamber," situated along the course of
one of these burrows, Dr. Anderson found no less than 68 bulbs stored up.
Its eyes are mere black specks among the muscles, but they appear, however,
to have a proper organisation. There are altogether eight species of the
genus, which is entirely Palaearctic in its range.

The genus _Rhizomys_, including a number of species known as Bamboo Rats,
is purely Oriental in range. _Rh. sumatrensis_ reaches a length of 19
inches; the better-known species, _Rh. badius_, is at most only 9 inches in
length--in both cases the measurements are exclusive of the tail, which is
a quarter to one-third of the length of the body, and is not scaly but
nearly naked, with a few scattered hairs. The molars are three, and the
incisors usually orange in colour; but sometimes the upper incisors are
white as in _Rh. badius_. There are thirteen dorsal vertebrae. In _Rh.
pruinosus_ the large intestine is considerably longer than the small
intestine; the lengths of the two sections of the gut are 42 and 30 inches
respectively. In another {483} species the large intestine is slightly
shorter than the small intestine. In _Rh. badius_ the two parts of the gut
are almost exactly equal in length. There are three pairs of inguinal and
two pairs of pectoral teats. The name _Rhizomys_ appears to have been given
to the animals of this genus for the reason that they feed largely on
roots. They burrow, and, like many other burrowing animals, feed in the
evening. As is the case with other forms, _Rhizomys_ is said to burrow with
the assistance of its teeth as well as of its claws.

[Illustration]

FIG. 237.--Bamboo Rat. _Rhizomys badius._ × ¼.

_Tachyoryctes_ is an African genus closely allied to the last. There are
three Ethiopian species. It is mainly to be distinguished by the different
pattern upon the grinding surface of the molars.

FAM. 5. GEOMYIDAE.--This family of burrowing Rodents is limited to North
and Central America. The animals have cheek pouches, and small eyes and
ears, in accordance with their mode of life. The claws of the fore-limbs
are very strongly developed.

The genus _Geomys_ contains some eight species, which are Central and North
American, not extending, however, far north. The incisors of the upper jaw
are grooved with two grooves. There are three pairs of teats--one axillary,
and the two remaining inguinal.

_Thomomys_, without grooves on the incisors, reaches to Canada in the
north, and does not extend as far south as the last genus. {484}

Allied to this family, and indeed united with it by Tullberg, but kept
separate by Thomas, is the

FAM. 6. HETEROMYIDAE.--The members of this family are also American, but
are not confined to the northern-central regions of that continent, for the
genus _Heteromys_ extends into South America.

The genus _Dipodomys_, with twelve species, is of a Jerboa-like form, as
the following measurements of an example of _D. merriami_ will show. The
length of the head and body was 85 mm.; of the tail 127 mm.; the hind-foot
is 32 mm. It has but four toes. The hind-limb is longer than the
front-limbs.

In _Perodipus_ the same form is exhibited. There are, however, five toes,
and the sole of the foot is hairy. The axis vertebra and the two following
vertebrae are fused together.

_Perognathus_ is a third genus. It has the same general slender form, but
the tail is not so long, being but little longer than the body. The
hind-limbs, too, are shorter. The teats of this and of _Perodipus_ are as
in _Geomys_. The two remaining genera of the family are _Heteromys_ and
_Microdipodops_.

[Illustration]

FIG. 238.--Jerboa. _Dipus hirtipes._ × 1/3. Eastern Europe.

FAM. 7. DIPODIDAE.--This family consists of small, plain-living, and
leaping or arboreal creatures, commonly known as Jerboas. The main
anatomical characters of the family are the following:--There is a large
infra-orbital foramen. The molars are always reduced, the premolar being
either absent in the lower jaw alone or in both jaws. This family presents
an obvious likeness to _Dipodomys_ (hence the name of the latter) and to
some other members of the American family Heteromyidae {485} There is even
the same ankylosis of the neck vertebrae. We find, moreover, the same
association of long-legged and shorter-legged forms that characterises the
Heteromyidae.

[Illustration]

FIG. 239.--Bones of right pes of Jerboa, _Dipus aegyptius_. × ¾. _a_,
Astragalus; _c_, calcaneum; _c_^2, middle cuneiform; _c_^3, outer
cuneiform; _cb_, cuboid; _n_, navicular; I-IV, first to fourth toes. (From
Flower's _Osteology_.)

The typical genus _Dipus_ is a smallish quadruped with long naked ears and
a long tail. The ten species are all Palaearctic in range. The fore-limbs
are short and five fingered, and the short pollex has no claw; the
hind-limbs are excessively long and only three-toed. The bony structure of
these limbs is remarkable. The three metatarsals are elongated almost like
those of a bird, and are ankylosed together. The digits have long phalanges
which alone reach the ground as the animal hops. It is a curious fact, and
one not so easily identifiable with the way of life, that the neck
vertebrae of this genus are ankylosed together with the exception of the
atlas, which is free; the arrangement is precisely like that of the Sperm
Whale. The last vertebra is, however, sometimes free. The Jerboas not only
leap but they burrow, and their strong incisors are said to be used in
burrowing through stony ground. They are eaten by the Arabs, and are, or
have been, called Daman Israel, _i.e._ Lamb of Israel. In _D. hirtipes_ the
body and tail measure respectively 4½ and 7 inches. The hind-feet have a
tuft of long hairs below. Mr. W. L. Sclater's newly-founded genus
_Euchoreutes_[351] is somewhat more primitive in its characters than is
_Dipus_. The general form is the same, with long ears and a long tail. But
there are five toes to the hind-limb, the two lateral ones though nailed
being much shorter than the middle three. It has a "long pig-like snout,"
and the tail is cylindrical as in most other Jerboas, with a tuft of longer
hairs at the end. The incisor teeth, grooved in _Dipus_, are here smooth,
as in _Alactaga_. The species was probably obtained "in the sandy plains
round the city of Yarkand." {486}

_Alactaga_ is much like _Euchoreutes_; it has five toes, a cylindrical
tufted tail, the hairs at the end distichous, smooth incisors, and a
premolar present in the upper jaw. It also differs from _Euchoreutes_ by
the much smaller auditory bulla as well as in the fact that the
infra-orbital foramen has no separate passage for the nerve, which passage
is to be distinguished in both _Dipus_ and _Euchoreutes_. The best-known
species is the Siberian Jumping Rabbit, _A. jaculus_. Beneath the ends of
the three main toes of the feet are remarkable fan-shaped pads. In _A.
decumana_ the body and tail measure 7 and 10 inches respectively, the ears
2 inches. _Platycercomys_, a fourth genus of the family, is much less known
and is to be differentiated from the last three genera by the fact that it
has no premolars at all, the grinding tooth formula being thus 3/3. The
tail too is flattened and "lancet shaped." It extends from Siberia to
Nubia, and thus just enters the Ethiopian region.

The above are the more typical Jerboas. There remain several forms which
are not at all Jerboa-like in their way of life, but are nevertheless, on
anatomical grounds, placed with them. _Zapus_, an American genus, with the
exception of one Palaearctic species, is transitional in that its hind-legs
are rather long, but there is not so much difference between them as in the
typical Dipodidae. _Sminthus_ is at the opposite extreme to _Dipus_. Its
feet are short and of equal length; it climbs in trees, and may perhaps be
looked upon as nearest of all Dipodidae to the ancestral form of the group.

FAM. 8. PEDETIDAE.--The genus _Pedetes_ contains but one species, _P.
caffer_, the Cape Jumping Hare. The animal suggests a large Jerboa in
appearance on account of its jumping habits, the long hind-limbs, and the
long tail. The length of a fair-sized example is some 17 inches, with a
tail of the same length. The eyes and ears are large. The hands are
five-fingered and the feet only four-toed, the hallux being of course the
absent digit. In the skeleton it is interesting to note that the second and
third cervical vertebrae are so close together that there can be no free
movement; interesting because in _Dipus_ the cervicals are actually
ankylosed. The dorsal vertebrae are twelve. The small intestine is long,
measuring 7 feet 4 inches, while the caecum is short, being only 8 inches
long. The large intestine is 3 feet 10 inches long. The gall-bladder
appears to be {487} absent,[352] an exceptional state of affairs in
Rodents. A singular fact in the anatomy of this animal is the existence of
a septum dividing the lower part of the trachea. This is sometimes met with
in birds. As might be supposed from its large eyes, the Spring Haas, as the
animal is sometimes called, is nocturnal. Its long hind-limbs permit it to
leap enormous distances. It is a burrowing Rodent.

SECTION 3. HYSTRICOMORPHA.

FAM. 1. OCTODONTIDAE.--The Rodents of this family are of small to moderate
size, the only, relatively speaking, giant in the family being the
"Water-Rat," _Myocastor_. The toes are with but one exception not reduced;
the tail is long in the majority of the genera. The teats are placed high
up on the sides of the body. The clavicle is fully ossified. All the genera
are South or Central American in range with the exception of
_Petromys_.[353]

SUB-FAM. 1. OCTODONTINAE.--_Octodon_ has four species, which are all
Chilian, Peruvian, and Bolivian in distribution. The Degu, _O. degus_, has
a length of 160 mm., with a tail 105 mm. long. The ears are 18 mm. long. At
the roots of the claws are longish and stiff hairs which appear to serve as
"combs." The tail has long but sparsely scattered hairs. There are twelve
pairs of ribs. The lengths of the various sections of the intestine are as
follows: small intestine, 680 mm.; caecum, 90 mm.; large intestine, 390 mm.
These animals live in large companies. Closely allied is the genus
_Habrocoma_ (more correctly, as it appears, to be written _Abrocoma_), with
two species. _H. bennetti_ is 204 mm. long, with a tail of 103 mm. The ears
are long, 22 mm. The fore-feet have no outward trace of the thumb. Stiff
hairs like those that characterise _Octodon_ are found also in this genus.
The fur is very soft. The furring of the tail is much thicker than in
_Octodon_.

_Spalacopus_ with but a single species, _S. poeppigi_, is a burrowing
animal, from which indeed, and on account of its resemblance to _Spalax_,
it has received its name. The ears in accordance with the underground life
are short, only 5 mm. in length in an {488} example of 120 mm. The tail too
is reduced, being in the same example only 42 mm. in length. As in the last
two genera the large intestine is about one half of the length of the small
intestine.

The "Tuco-tuco," genus _Ctenomys_, has also short ears and tail. The claws
of the fore-feet are longer than those of the hind-feet.

A related form is _Aconaemys_ (better known as _Schizodon_), with similar
external characters; it inhabits high localities on the Andes.

_Petromys_ is the only genus of the sub-family which is not American in
habitat. It is an African form and there is but one species. Its anatomy
conforms to that of the genera already considered. The main difference in
structure is shown by the teeth. Their surface is uneven, and differs from
that of other Hystricomorphs "in that the enamel to the inside of each
upper jaw-tooth and outside on each lower jaw-tooth forms two tubercles, to
which correspond grooves in the reverse position of the applied teeth."

SUB-FAM. 2. LONCHERINAE.--The genus _Echinomys_ with thirteen species
belongs to the Neotropical region. The members of the genus are entitled
"Spiny Rats" since they have spines mixed with the fur. The tail is long
and the ears are very well developed. Both feet are five-toed. The tail is
scaly as well as haired. _Trichomys_ (also called _Nelomys_) is very close
to the above, and is also from the same part of the world.

The genus _Cannabateomys_ contains but one species, _C. amblyonyx_, which
was formerly included in the genus _Dactylomys_, but has lately been
separated by Dr. Jentink.[354] The animal is Brazilian and has a total
length of 520 mm., of which 320 mm. belong to the tail. It is a climbing
rat, and in accordance with that way of life has undergone some
modifications. The fore-feet are four-toed, the two middle toes being
markedly longer than the outer ones. The hind-feet are five-toed with the
same greater development of the two middle toes. The claws are small and
somewhat nail-like.

_Dactylomys_, also Brazilian, and with but one species, _D. dactylinus_,
differs from the last in the fact that the molars are simpler in form; they
are divided into two lobes, each of which {489} has but a single enamel
fold, whereas in _Cannabateomys_ these teeth have several enamel folds. The
tail, moreover, is but slightly hairy.

_Loncheres_ with eighteen species is another Neotropical genus allied to
the foregoing. Small spines are, as in many of these genera, intermingled
with the fur. This genus has as many as seventeen dorsal vertebrae, which
is an unusually large number. _L. guianae_ is known as the "Porcupine Rat."
Allied genera, also South American, and without spines in their fur, are
_Mesomys_, _Cercomys_, and _Carterodon_.

The South American _Thrinacodus_ is also known by one species,[355] _T.
albicauda_, which has rather more than the distal half of the long tail of
a white colour. The fore-feet have four toes. The ears are broad and short.

SUB-FAM. 3. CAPROMYINAE.--A third sub-family of the Octodontidae is formed
by the genera _Myocastor_, _Capromys_, _Plagiodontia_, and _Thrynomys_,
which are all Neotropical forms with the exception of the last, which is
African.

_Thrynomys_ (better known perhaps as _Aulacodus_) is a genus of African
Rodent, containing some four species. The best-known of these is _T.
swindernianus_, the Ground-Rat of West and South Africa. Its structure has
been investigated by Garrod,[356] by Tullberg,[357] and by myself.[358] The
fur is mingled with flattish bristles; the tail is moderately long, about
half as long as the body. The fore-feet are five-toed, but the two toes at
each end of the series are quite small. The hind-feet are only four-toed,
the hallux being absent. The claws of the hind-feet are stronger than those
of the fore-feet. The ears are not long. The limbs are decidedly short,
hence the name of "Ground-Pig" sometimes applied to this animal. The molars
are four in number in both jaws. The incisors of the upper jaw are twice
grooved. There are thirteen dorsal vertebrae. The length of the small
intestine is 60½ inches, that of the large 49; the caecum is short, being
only 8 inches long. It is a remarkable fact that the acromion is joined to
the rest of the spine of the scapula by a joint.

_Myocastor_, a name which seems to have the rights of priority over the
more familiar _Myopotamus_, applies to a large South American aquatic
Rodent. The general aspect of the animal {490} suggests a Water-Rat of
large size (it has been exhibited in shows as a phenomenal product of
London sewers!); the tail is nearly as long as the body. The ears are
small. The limbs are short. The tail is naked. The hind-feet are webbed,
but not so much so as in _Hydromys_. A small thumb is present. The animal
has thirteen pairs of ribs; the molars are four in each jaw. The large
intestine is more than three times the length of the small, and the caecum
is, as in the last genus, relatively short.

_Capromys_ is a genus[359] which is remarkable on account of its restricted
distribution. It is found only in the islands of Cuba and Jamaica. There
are four species, of which _C. melanurus_ is a dark brown-coloured animal
with a blacker tail, nearly as large as a Rabbit. The native name of this
Rodent is "_hutia_." It is also remarkable for having a stomach more
complicated than is the rule among the mammals of this group. The organ is
divided by two constrictions into three compartments. In _C. pilorides_ the
liver is occasionally divided up in an extraordinary fashion into small
lobules. _Capromys_ has the large number of sixteen dorsal vertebrae.

FAM. 2. CTENODACTYLIDAE.--For these African genera it seems admissible to
form a distinct family, though Thomas, and Flower and Lydekker, only allow
to the genera _Ctenodactylus_, _Pectinator_, and _Massoutiera_ sub-family
rank. On the other hand, Tullberg removed these genera entirely from the
Hystricomorph section and placed them as a section of the sub-tribe
Myomorphi of the tribe Sciurognathi. It was chiefly the form of the
mandible which led to this placing, for in these Rodents, as in all
Squirrel- and Rat-like Rodents, and unlike what is found in the
Hystriciform genera, the angular process of the mandible is not bent
sideways.

The genus _Ctenodactylus_ derives its name from the peculiar strong
bristles which form a comb-like structure upon the hind-feet and hide the
claws; these are stated to be for the purpose of dressing the fur. The
Gundi of North Africa, _C. gundi_, has a length of 190 mm., with a short
tail of 17 mm. The ears are only moderate in size. The dental formula of
the molars is 4/3. The incisors are white. The feet have four digits, and
the hind-limbs are the longer. The large intestine is distinctly longer
than the small intestine. {491}

_Pectinator spekii_ is the only representative of a genus not far removed
from _Ctenodactylus_; it is a smallish Rodent, 6 inches in length,
exclusive of a rather bushy tail nearly 3 inches long. It comes from
Abyssinia. It has somewhat the appearance of a Squirrel, which is
heightened by the fact that when sitting the tail is arched over the back;
when running the tail is carried out straight. There are only four toes
visible externally on both fore- and hind-limbs, but pollex and hallux
exist in the skeleton, with a single phalanx each. There is only a single
pair of mammae, and in correspondence with this but two or three young are
produced at a time. The hind-feet have bristles very much like those of
_Ctenodactylus_. The molars, however, are 4/4. There are twelve ribs, of
which six reach the sternum. The latter is made up of six pieces, and the
manubrium in its breadth anteriorly suggests that of the Vizcachas. The
clavicles are present.[360]

[Illustration]

FIG. 240.--Carpincho. _Hydrochoerus capybara._ × 1/12.

FAM. 3. CAVIIDAE.--This family, which includes the Cavies and the Capybara,
is entirely South American and West Indian in distribution. It embraces
animals of fair to large size, the Capybara {492} (or Carpincho) being the
greatest of existing Rodents. The ears are well developed. The toes are
commonly reduced, and the members of this family possess only a rudimentary
tail. The hair though rough is not spiny. Other characters had best be
deferred until the several genera are treated of. We shall begin with the
giant of the family, the genus _Hydrochoerus_. This genus contains but a
single species, _H. capybara_ of South America. It reaches a length of some
4 or 5 feet. The ears are not large; the tail is completely absent. The
fore-feet are four-toed, the hind-feet three-toed; the digits are webbed,
though not to a very great degree, and the nails have the appearance of
hoofs. There are fourteen dorsal vertebrae; the clavicle is absent. In the
skull the paroccipital processes are of great length. The infra-orbital
foramen is large. The most remarkable fact about the teeth is the great
size of the posterior molar of the upper jaw; it has fourteen folds of
enamel, more than all the anterior teeth possess collectively. The incisors
are white and grooved in front. The measurements of the alimentary tract as
given by Tullberg are: small intestine, 4350 mm.; caecum, 450 mm.; large
intestine, 1500 mm.

[Illustration]

FIG. 241.--Patagonian Cavy. _Dolichotis patachonica._ × 1/10.

The Capybara or Carpincho is largely aquatic in its habits. Their
"favourite locality," writes Mr. Aplin,[361] "is a broad laguna {493} in
the river, furnished with open water, and also beds of 'camelotes,'--a
sloping open grassy bank on one side, where the Carpinchos can lie in the
daytime in the cooler weather, sleeping and basking in the sunshine; on the
other a low shelving bank, clothed with 'Sarandi' scrub growing out into
the black reeking mud and shallow water beyond." They always take to the
water when alarmed, at a rate and with a gait which reminded Mr. Aplin of a
Pig. When in the water they swim slowly with the upper part of the head,
including nose, eyes, and ears, above the surface. But they can dive for a
considerable time and distance, and baffle their enemies by seeking the
shelter of a mass of water-plants, and lying there with their noses only
just above the surface.

The genus _Dolichotis_[362] has long ears, and generally resembles a rather
long-legged Hare in appearance. The front-feet are four-toed, the hind
three-toed. The Patagonian Cavy, as this animal is called, has twelve
dorsal vertebrae, and rudimentary clavicles.[363] The paroccipital
processes are long; the incisors are white, and are not grooved in front.
The sternum has six pieces, and seven ribs reach it.

_Cavia_, including the species _C. porcellus_, the Guinea-pig (which name
is a corruption apparently of Guiana pig), has the same number of toes on
its hind- and fore-feet as has the Capybara. The name applied to the wild
stock whence our Guinea-pig is derived is the Restless Cavy. The fur is
greyish; of the domestic animals the colour is too well known to need
description.

FAM. 4. DASYPROCTIDAE.--The genus _Coelogenys_ includes but two species.
_C. paca_, known as the "Spotted Cavy" or "Paca," has a brown body, with
white spots like those of a Dasyure; it is one of the largest of Rodents,
and has a quite short tail. The hand and foot are both provided with five
digits; but the thumb is small, and in the foot the three middle toes
considerably exceed the others in length. The hind-foot is practically
three-toed. The fibula is not nearly so reduced as in _Dolichotis_. The
skull of the animal is remarkable for the extraordinary development in
breadth of the jugal arch, which is sculptured externally. There is a large
cavity formed below, at the maxillary end of this huge {494} arch, by the
curving inwards of the bone, which lodges a cavity continuous with the
mouth. The palate has anteriorly a ridge on either side, and is thus
divided from the sides of the face in a way which is not found[364] in the
allies of _Coelogenys_. Clavicles are present. There are thirteen dorsal
vertebrae. The incisors are coloured red in front. The animal is South
American, and in that continent is limited to the Brazilian sub-region.
This, the best-known species of Paca, is called the Gualilla by the natives
of Ecuador; in the same district another form is met with which the natives
term Sachacui (signifying Forest Cavy). It is very often the case that a
different native name expresses a real specific difference; and to the
latter form M. T. Stolzmann has given the name of _C. taczanowskii_.[365]
This form, unlike the common Paca, which is fond of forests and low-lying
ground in the neighbourhood of water, is alpine in habitat, living upon
mountains of 6000 to 10,000 feet. It burrows in much the same way as its
congener, and is greatly sought after as food, its meat possessing an
"exquisite taste." It is pursued by dogs, by whose aid one of the two
entrances to the burrow is guarded, and the creature is smoked out and
killed with a stick.

The genus _Dasyprocta_, containing those Rodents known as Agoutis, is
divisible into several species, apparently about twelve, all of which are,
like the Pacas, confined to the Neotropical region. They have, however, a
much wider range within that region, and occur as far north as in Central
America and in some of the West Indian Islands. They are of rather smaller
size than the Paca, and are without spots. The colour is of a golden brown
in some forms, but usually has a freckled, grizzled, greenish kind of
appearance. The tail is stumpy, the hind-limbs are distinctly longer than
those of the Paca, and the two lateral toes have disappeared from the
feet--a concomitant as it seems of the Agouti's greater powers of running.
The three metatarsals are closely pressed together, and the foot is as it
were on the way towards the highly-modified foot of the Jerboa. The
fore-feet are, however, five-toed. The clavicle is rudimentary,[366]
whereas it is well developed in the Paca. The skull has not the peculiar
modifications of that of the last-mentioned type. The sternum has seven
{495} pieces, and eight ribs reach it. A curious difference between this
genus and the last is in the relative proportions of the regions of the
intestine. The figures given by Tullberg for the two animals are--for
_Coelogenys_, small intestine, 4800 mm.; caecum, 230 mm.; large intestine,
21,000 mm.;--for _Dasyprocta aguti_ the same author gives: small intestine,
4200 mm.; caecum, 200 mm.; large intestine, 1000 mm. The Agouti, says Mr.
Rodway,[367] is as wily as the Fox. "If chased he will run along the
shallows of a creek to hide his scent from the dogs, or swim over and back
again several times for the same purpose. He never runs straight when
pursued, but doubles, often hiding until a dog has passed, and then making
off in a different direction. Like the fox he has been hunted for a very
long period, and, like Reynard, has grown wiser with every generation."

[Illustration]

FIG. 242.--Agouti. _Dasyprocta aguti._ × 1/10.

FAM. 5. DINOMYIDAE.--The genus _Dinomys_ of Dr. Peters[368] is a very
little known and remarkable form from South America allied to the Capybara,
the Chinchilla, and other South American Rodents. It is only known by a
single example found wandering about a courtyard in a town of Peru. It is
externally like, and of about the same size as the Paca, but has a hairy
tail. The animal is four-toed and plantigrade; the ears are short, and the
nostrils are [369]-shaped. It is usually regarded as belonging {496} to a
separate family which will include but the one species, _D. branickii_.

FAM. 6. CHINCHILLIDAE.--This family, likewise South American, contains
three genera,[370] all of which agree in having long limbs, especially the
hind-limbs, and a bushy and well-developed tail. The hair is exceedingly
soft, hence the commercial value of "chinchilla."

The genus _Chinchilla_, containing but a single species, _C. laniger_, is a
small and squirrel-like creature, living at considerable heights in the
Andes. The eyes, as it is a nocturnal creature, are naturally large; and so
also are the ears. The fore-feet have five toes, the hind-feet only four;
they are furnished with feeble nails. The innermost toe of the hind-foot
has a flat and nail-like claw. There are thirteen dorsal vertebrae, and the
long tail has more than twenty. The clavicle is well developed, as in the
other genera of this family. The large intestine of this animal is
extraordinarily long; the proportions of the different regions of the gut
are shown by the following measurements: small intestine, 820 mm.; caecum,
125 mm.; large intestine, 1340 mm. Such a disproportion between the large
intestine and the small, to the advantage of the former, is a very strange
fact in the anatomy of this Rodent.

The genus _Lagidium_ (also called _Lagotis_), which includes "Cuvier's
Chinchilla," is also a mountain dweller. There are several species of this
genus, which differs from _Chinchilla_ by the complete abortion of the
thumb and of the great toe. The intestinal proportions are those of
_Chinchilla_. The ears and tail are long. _L. cuvieri_ measures 1½ feet in
length.

_Lagostomus_, again, has but one species, _L. trichodactylus_. The animal
has a tail about half the length of the body. The digits are reduced as
compared with _Chinchilla_, there being but four on the fore- and three on
the hind-feet. There are only twelve dorsal vertebrae, and seven ribs reach
the sternum. In the skull a distinguishing mark from the last two genera is
the separation of the infra-orbital foramen into two by a thin lamella of
bone. The large intestine is between one-half and one-third the length of
the small intestine, and thus differs much from that of _Chinchilla_. {497}

[Illustration]

FIG. 243.--Vizcacha. _Lagostomus trichodactylus._ × 1/10.

The Vizcacha lives in societies of twenty to thirty members,[371] in a
"village" ("Vizcachera"), a dozen or so of burrows, which intercommunicate.
They lie at home during the day and come out in the evening. Their burrows,
like those of the Prairie Marmot, harbour other creatures, which apparently
live on amicable terms with the Vizcachas; such are the burrowing owl, a
small swallow, and a _Geositta_. The Fox also affects these burrows, but
then he ejects the rightful owner of the particular burrow which he
selects. When the young Foxes are born the vixen hunts the Vizcachas for
food. The Vizcacha has a most varied voice, producing "guttural, sighing,
shrill, and deep tones," and Mr. Hudson doubts if there is "any other
four-footed beast so loquacious or with a dialect so extensive." These
animals are very friendly, and pay visits from village to village; they
will attempt to rescue their friends if attacked by a Weasel or a Peccary,
and to disinter those covered up in their burrows by man.

FAM. 7. CERCOLABIDAE.--A number of the characters which differentiate this
family from the Hystricidae or Ground Porcupines of the Old World are given
under the description of the latter. The principal external characters are
the prehensile tail, the admixture of spines with hairs, and the nature of
the sole of the foot. In these points the New-World Cercolabidae differ
from the Old-World Hystricidae. It is interesting to notice that {498} in
both families we have long-tailed and short-tailed forms. _Cercolabes_
corresponds to _Atherura_ or _Trichys_, and _Erethizon_ to _Hystrix_.

The genus _Erethizon_, the "Urson" of Canada, has a short, stumpy tail. Its
spines are almost hidden by enveloping hair. The fore-feet have four, the
hind-feet five toes. The short tail of this creature is remarkable when we
reflect upon its climbing habits. It appears, however, to be a weapon with
which it strikes sideways at the enemy.

[Illustration]

FIG. 244.--Brazilian Tree Porcupine. _Sphingurus prehensilis._ × 1/6.

Of the Neotropical genus _Cercolabes_ (sometimes called _Sphingurus_,
_Synetheres_, or _Coendou_) there are some eight or nine species, all found
in Central and South America. The animal is arboreal, and has in
correspondence with that habit a prehensile tail. The spines are not so
stout as in the Ground Porcupines, and are often coloured yellowish or
reddish. In correlation with its tree-frequenting habits the bones of
_Cercolabes_ show certain differences from those of the Ground Porcupines.
The scapula is broader and rounder in front than is that of _Hystrix_; the
phalanges of the thumb (which is rudimentary) are fused together as in the
Canadian _Erethizon_; but those of the very small hallux are also fused,
whereas in _Erethizon_, as in _Hystrix_, they are separate. In one species,
_C. insidiosus_, Sir W. Flower states that there are as many as seventeen
dorsal vertebrae and thirty-six caudals. The tail is thus very long. In _C.
villosus_ there are fifteen dorsals and twenty-seven caudals; eight ribs
reach the sternum, which is composed of seven pieces, the {499} sixth being
very small. The clavicles are well developed. A curious fact about _C.
villosus_ is that the acetabular cavity is perforate (on both sides), or at
least only closed by membrane. In many forms of Rodents the bone is very
thin in this region. This fact perhaps lessens the significance of the
perforation of the acetabulum of _Echidna_ (see p. 109).

Of the allied genus _Chaetomys_, also Neotropical, there is but a single
species, which inhabits Brazil. It has a nearly completely closed orbit, a
feature which differentiates it from the last animal, and one which also
shows it to be a more modified form. The spiny covering is less pronounced
than in its allies.

FAM. 8. HYSTRICIDAE.--This family is characterised by the fact that all its
members possess spines; but the tail, if at all long, is not prehensile,
and the soles of the feet are smooth and not covered with rough tubercles,
as in the Tree Porcupines of the next family, Erethizontidae. The clavicle
is less developed than in the arboreal forms. In the organs of digestion
there are points of a family difference between the two groups of spiny
Rodents. The tongue has serrated scales arranged in transverse rows, which
are directed backwards. A gall-bladder, though not always present, is
sometimes found; it apparently never exists in the arboreal Porcupines and
in _Erethizon_. The lungs show a great tendency to subdivision, which
appears to be especially marked in the genus _Atherura_. The caecum seems
also to be shorter in the Ground Porcupines. In _Hystrix cristata_ the
small intestine measures 15 feet 7 inches; the caecum, 8 inches; the large
intestine, 4 feet 4 inches:--in _Atherura africana_ the caecum measures 7½
inches; the large intestine, 1 foot 10 inches. The corresponding
measurements of _Synetheres villosus_ were: small intestine, 7 feet 3
inches; caecum, 1 foot 4 inches; large intestine, 2 feet 7 inches. In
_Erethizon_ the caecum is 2 feet 4 inches in length. These differences are
too large and too constant in a number of presumedly allied forms to be
overlooked.

Mr. Parsons has directed attention[372] also to a number of muscular
differences, such indeed as might be expected to occur between animals of
such different habits.

The genus _Hystrix_ embraces the better-known Porcupines. It is a genus of
wide range, extending from the East Indies to Africa, {500} and even
occurring in Europe. There are several species, of which the common
_Hystrix cristata_ is the best known, and is the one which is to be found
in Europe.

[Illustration]

FIG. 245.--Common Porcupine. _Hystrix cristata._ × 1/10.

The spines of the common form and of the others are solid in the middle of
the body, but on the tail they are expanded into hollow quills, which make
much rattling. They are as a rule black and white, the middle of the spine
being banded with black. A great crest of coarse long hairs on the head is
responsible for the scientific name of the well-known form. Sometimes in
this genus, as in the Tree Porcupines of Brazil, the spines are orange or
yellow; but it is said that the colour is soon lost in this country. As a
matter of fact it is the easiest thing in the world to wash out with
ordinary tap-water much of the yellow colour of the spines of the South
American _Sphingurus_. The same may be the case with the pigment of the
Old-World Porcupines. There are fourteen to fifteen dorsal vertebrae and
four or five lumbars. The tail varies in length, but is shorter than the
long tail of the arboreal New-World forms. It seems impossible when
mentioning the Porcupine to escape from some observations about its alleged
habit of shooting its quills. For some reason or other Buffon has got the
credit of inventing, or at {501} least promulgating, this legend, which has
even grown so in the telling that the quills are said to be capable of
penetrating planks of wood. What Buffon said _apropos_ of this matter is,
"The marvellous commonly is pleasingly believed, and increases in
proportion to the number of hands it passes through." It is of course the
rattling of the spines and the occasional falling out of loose ones which
has started the legend. They are, however, excellent weapons of offence,
and the animal charges somewhat backwards to make the best use of them
against the foe. The spines, however, are by no means an absolute
protection, since, as Mr. Ridley informs us,[373] Tigers will kill and eat
these animals just as the Thylacine is apparently indifferent to the spiny
armature of _Echidna_.

Of the Brush-tail Porcupine, _Atherura_[374] there are at any rate two
species, the West African _A. africana_ and the Malayan _A. fasciculata_.
It is interesting that the gap in the present distribution is partially
filled by the discovery of fossil teeth near Madras. The genus does not
differ widely in external appearance from _Hystrix_; it has, however, a
rather longer tail; there are fewer large spines, and there is a tuft of
them at the end of the tail, whence is derived the name of the genus. The
frontal bones project a little distance between the nasals, a feature which
does not seem to appear in the true Porcupines. There are fourteen dorsal
vertebrae and five lumbars. The twenty-four caudal vertebrae of this
Porcupine shows how much longer is its tail than that of _Hystrix_; for in
the latter twelve is about the number.

A third genus of Old-World Porcupine is the singular _Trichys_.[375] Of
this there is but one species, _T. lipura_. It is a curious fact that out
of three examples, all from Borneo, two were quite without a tail. But this
appears to be merely a mutilation, though it is singular that the natives
state it to be without a tail. One cannot help thinking of the way in which
lizards sometimes shed their tails when pecked at. The tail of this genus
is more than half the length of the body and head. _Trichys_ has sixteen
dorsal and six lumbar vertebrae. There is a tuft of quills at the end of
the tail, which are thin and compressed, {502} though truncate at the free
extremity and hollow; they represent in a more rudimentary way the much
stronger tuft at the end of the tail of other Porcupines. It is a curious
fact that this and other Porcupines possess a mechanism for warning their
foes precisely comparable to that of the rattlesnake. There are sixteen
dorsal vertebrae.

SUB-ORDER 2. DUPLICIDENTATA.

The chief feature of this group is the existence of two pairs of incisor
teeth in the upper jaw, of which the inner are very small and lie behind
the outer. In the skull the infra-orbital foramen is small; the incisive
foramina are very large. The tail is short or absent.

FAM. 1. LEPORIDAE.--This family is distinguished from the Lagomyidae by the
long ears, by the tail, which is present, though short, and by the longer
limbs. There are six teeth belonging to the molar series in the upper jaw,
and five of the same in the lower. The clavicle is imperfect.

The longest known genus of this family, _Lepus_, was, until the quite
recent discovery of _Romerolagus_, the only genus. It is of universal
range, excepting Australasia and Madagascar, and consists of about sixty
species. These are the Hares and Rabbits, to the former being assigned the
longer-limbed forms.

As every text-book of zoology contains a more or less elaborate account of
the structure of the Common Rabbit, and as there is but little structural
difference between the members of the genus, a short account of the generic
peculiarities of _Lepus_ will suffice here. The fore-feet are five-toed,
the hind-limbs four-toed. The hairy integument enters the mouth cavity, and
the inside of the cheeks have a hairy covering. The soles of the feet are,
moreover, hairy. The maxillary bones are curiously sculptured.

[Illustration]

FIG. 246.--_Lepus cuniculus._ Skull. A, Lateral view; B, ventral view.
_ang.pro_, Angular process of mandible; _as_, alisphenoid (external
pterygoid process); _aud.me_, external auditory meatus; _b.oc_,
basioccipital; _b.sph_, basisphenoid; _cond_, condyle; _cor_, coronoid
process; _fr_, frontal; _int.pa_, inter-parietal; _ju_, jugal; _lcr_,
lachrymal; _max_, maxilla; _nas_, nasal; _opt.fo_, optic foramen; _o.sph_,
orbitosphenoid; _pa_, parietal; _pal_, palatine; _pal.max_, palatine plate
of maxilla; _pal.p.max_, palatine process of premaxilla; _par.oc_,
paroccipital process; _peri_, periotic; _p.max_, premaxilla; _pt_,
pterygoid; _p.t.sq_, post-tympanic process of squamosal; _s.oc_,
supraoccipital; _sq_, squamosal; _ty.bul_, tympanic bulla; _vo_, vomer;
_zyg.max_, zygomatic process of maxilla. (From Parker and Haswell's
_Zoology_.)

The Common Rabbit, _L. cuniculus_, differs from the Common Hare in the
comparatively shorter ears and legs. The ears have not, to so marked a
degree, the black tips of those of the Hare. The animal, moreover, produces
naked young, and lives in burrows of its own excavation. A difference in
the structure of the caecum, which distinguishes the Rabbit from the Hare,
has been {504} pointed out by Professor W. N. Parker.[376] These
differences have led some to approve of its separation from the Hares into
a genus _Oryctolagus_. This animal is believed to be an introduced species,
and to have been brought by man into these islands. Its original home is
the Spanish Peninsula, the south of France, Algiers, and some of the
Mediterranean islands. Mr. Lydekker thinks that the only other species of
_Lepus_ which can be considered to be a "Rabbit" is the Asiatic _L.
hispidus_.

Of Hares there are two species in this country. The Common Hare, _L.
europaeus_ (the name _L. timidus_ seems to be really applicable to another
species to be referred to presently), extends all over Europe excepting the
extreme north of Russia and Scandinavia. It is not known in Ireland, and,
curiously enough, attempts to acclimatise this animal in that island have
failed--a state of affairs which contrasts with the fatal ease with which
the Rabbit has been introduced into Australia. Ireland has, however, the
Variable Hare, _L. timidus_ (also called _L. variabilis_), a species which
is common in other parts of Europe, and which extends as far east as Japan.
This species differs from its ally by the fact that it often turns white in
winter with the exception of the black tips to the ears. In Ireland this
change does not always occur; but Mr. Barrett-Hamilton has commented upon
the fact that Hares of this species do change on Irish mountains. It
appears that in this animal the change from the winter to the summer dress
is accomplished by the actual casting off of the white hairs and their
replacement by a fresh growth of "blue" hairs. A similar change occurs in
the American _L. americanus_.

Dr. Forsyth Major has noted the fact that the various species of Hares can
be distinguished by the condition of the furrows upon the upper incisors.
Thus two African species, _L. crawshayi_ and _L. whytei_, are to be
separated by the fact that in the former the incisors are quite flat,
whereas in _L. whytei_ the groove is more prominent and there is a second
shallow furrow.

The genus _Romerolagus_[377] is quite a recent discovery. It occurs on the
slopes of Popocatepetl in Mexico; it has the general aspect of the last
genus, and is spoken of as a "Rabbit." It inhabits runs in the long grass
which clothes the sides of the {505} mountain. Externally it is something
like the Pikas, since it has no tail visible. The ears, too, are short, and
the hind-legs comparatively short. The skull is very like that of the
Rabbit; but in other osteological details it is aberrant. Thus the clavicle
is quite complete, and only six ribs articulate with the sternum, instead
of the seven that we find in the Rabbit.

FAM. 2. LAGOMYIDAE.--The animals of this family are smaller than the Hares
and Rabbits; they have short Vole-like ears and no external tail. The limbs
also appear to be shorter. As there is but a single genus, the characters
of the family may be described in connexion with those of the genus, which
is known as _Lagomys_ (apparently more correctly _Ochotona_). Of this genus
there are about sixteen species, which are mainly Asiatic; one species
extends its range into Eastern Europe, and three are North American.

The skull has not the supra-orbital grooves of the Rabbits, and has a
well-marked backward process of the zygomatic arch. There are eighteen
dorsal vertebrae. The molars and premolars are five.

The vernacular names of "Pika" and "Piping Hares" have been applied to the
members of this genus, the latter on account of their peculiar call. They
live among rocks in companies and they burrow. They are usually found at
considerable altitudes: thus _L. roylei_, the "Himalayan Mouse Hare," is
found at elevations as high as 16,000 feet; while _L. ladacensis_ gets even
higher, 19,000 feet having been recorded. With the habits of a Marmot, so
far as concerns living in burrows and at great altitudes, the animals of
this genus, with their squat form and short ears, are not unlike those
animals. In the past this genus occurred more generally over Europe.
Species from Miocene beds have been met with in England, France, Germany,
and Italy.

FOSSIL RODENTS.--Quite a large number of existing genera of Rodents are
known from even the earlier strata of the Tertiary period. The Squirrels
(and even the genus _Sciurus_ itself) occur in the Upper Eocene. So, too,
do the genera _Myoxus_, and (in South America) _Lagostomus_.
_Spermophilus_, _Acomys_, _Hystrix_, _Lagomys_, _Lepus_, _Hesperomys_ are
known from Miocene rocks. _Rhizomys_, _Castor_, _Cricetus_, _Mus_,
_Microtus_, and some others appear to have originated so far as we know in
the Pliocene, while a still larger series of existing genera are
Pleistocene. It is interesting {506} to note that some of the extinct
genera were much larger than recent forms. At present, _Hydrochoerus_ is
the biggest Rodent; but the genus _Megamys_ from the Pampas formation of
Argentina was "nearly as large as an ox." The wider range of genera in the
past is illustrated by _Hystrix_, which, now an Old-World form, is
represented by remains in the Miocene and Pliocene of America.

It is a significant fact that of living genera _Sciurus_ is the oldest; for
it has been pointed out that in a number of features the Squirrels are
among the most primitive of Rodents. The zygomatic arch is slender, and has
thus not acquired the specialisation that is to be found in that part of
the skull in other Rodents; moreover, the "jugal bone is not supported by
any process from the maxilla exactly as in the primitive Ungulata." The
feet, too, are unspecialised, though that is the case with many other
genera. It may also be pointed out that the teeth bear not a little
likeness to those of _Ornithorhynchus_ in their multituberculate character.

Some few fossil forms have already been dealt with in the preceding pages.

The two genera _Castoroides_ and _Amblyrhiza_, from the Pleistocene of
North America and the West Indies, are usually regarded as forming a
family. The skull of the former genus indicates an animal of the size of a
Bear. It is compared to that of _Castor_, but it has a wide infra-orbital
foramen. The teeth are four in each jaw, and are formed of three to five
lamellae; the incisors of this animal are powerful but short. _Amblyrhiza_,
on the other hand, has long incisors which are longitudinally grooved
anteriorly. It has a free fibula. This latter as well as other characters
have led Tullberg to remove it from association with _Castoroides_.

ORDER X. TILLODONTIA.

This group of Eocene mammals is to be defined by a number of characters, of
which the more important are the following:--The incisors are enlarged,
grow from persistent pulps, and are coated with enamel upon the outer
surface only; they are those of the second pair only, the first and third
having disappeared or become small. The canines are reduced in the later
forms. {507}

[Illustration]

FIG. 247.--_Tillotherium fodiens._ Left lateral view of skull. (From
Flower, after Marsh.)

These animals have been regarded as ancestral Rodents, to which the tooth
characters just mentioned clearly show likenesses. The earliest known form
is _Esthonyx_. This genus shows such primitive characters, compared with
its later representatives, as the existence of all three pairs of incisors
in the upper jaw, but only two in the lower jaw. The enlarged incisors of
both jaws do not seem to have grown from persistent pulps.

_Anchippodus_, a later form, still preserves the upper pair of first
incisors in a vestigial form; the strong second incisors grew from
persistent pulps. The most recent genus, _Tillotherium_, shows the
characteristics of the group at their height. The strong Rodent-like,
chisel-shaped incisors, which are reinforced by a small additional pair in
the upper jaws only, are persistent. The grinding teeth are of the
tritubercular pattern; there are three of each kind in the upper jaw, but
in the lower jaw only two premolars on each side. This is at any rate the
case with some, while others have three. The canine, though present in both
jaws, is insignificant. As in many ancient types, there is an
entepicondylar foramen in the humerus. The feet were five-toed, and bore
sharp, laterally-compressed claws. The skull has been compared in general
aspect to that of a Bear.

       *       *       *       *       *


{508}

CHAPTER XVI

INSECTIVORA--CHIROPTERA

ORDER XI. INSECTIVORA.

The Insectivora[378] are an order of mammals to which it is (to quote
Professor Huxley) "exceedingly difficult to give a definition." They are,
however, none of them large animals, and most of them are nocturnal in
habit--two circumstances which may have had something to do with their
survival from past ages, as may have also their modification to so many and
diverse modes of life; for everything points to the antiquity of the group.
They are, for instance, more or less plantigrade. The snout is generally
long, and is often prolonged into a short proboscis.[379] There is a
tendency for the teeth to be of a generalised type, and their number is
often the typical mammalian forty-four. Moreover, trituberculate teeth,
which are certainly an ancient form of tooth, are common; and indeed the
Insectivora of the southern regions of the globe, _e.g._ Centetidae,
Solenodontidae, and Chrysochloridae, have the most prevalent
trituberculism, a fact which is of importance in considering the age of the
animal life of these regions of the world. The limbs are, as a rule,
provided with five digits. The hemispheres of the brain are usually smooth,
and do not extend over the cerebellum. The palate is often fenestrate as in
the Marsupials, and as in that group the lower jaw is sometimes inflected.
But the latter character also occurs in the Sea-lions and elsewhere.
Clavicles are present, as a rule, but not in _Potamogale_. {509}

There is, furthermore, a distinct tendency towards a disappearance of
functional milk teeth, which is best seen in _Sorex_, where there are only
seven milk teeth, none of which ever cut the gum. This suppression of the
milk dentition is like that of the Marsupials, Edentates, and Whales, all
of which appear to be--the first certainly are--ancient forms of mammalian
life.

There is also a fairly well-defined, though shallow, cloaca in many genera.
Finally, the testes are purely abdominal in some, and in none is there a
full descent into a scrotum, as in the more highly-developed Eutheria.

SUB-ORDER 1. INSECTIVORA VERA.

FAM. 1. ERINACEIDAE.--This family contains the genera _Erinaceus_,
_Hylomys_, and _Gymnura_.

_Hylomys_, considered by Dobson to fall within _Gymnura_, is kept separate
by Leche.[380] _H. suillus_ is a Malayan animal, small in size, about 5
inches long, with a short tail. Like _Gymnura_ it is spineless. The ears
are decidedly large and nude. There is one pair of inguinal and one pair of
thoracic teats. The colour above is a rusty brown with yellowish-white
under parts. The palms and soles are quite naked. In its general form it
recalls _Tupaia_ very much more than its own immediate relatives. There is
no doubt, however, of its systematic position when the skeleton and teeth
are examined. A variety has been described from altitudes of 3000 to 8000
feet on Mount Kina Balu in Borneo. It has the complete dentition of
forty-four teeth. There are fourteen pairs of ribs. As in _Gymnura_ the
tibia and fibula are united below. The genus is considered by Leche to be
the oldest existing type of Erinaceidae.

_Gymnura_[381] is also a Malayan form with the complete dentition of the
last, but with fifteen pairs of ribs and a longer tail, consisting of
twenty-three vertebrae as against fourteen. There is, as with _Hylomys_,
but one species, _G. rafflesii_. This animal has a peculiar odour,
resembling decomposed cooked vegetables. {510} The under surface of the
tail is rough, and it is thought by Dr. Blanford that it may be of use to
the animal in climbing. Its compressed terminal third and the fringe of
stiff bristles on the under surface of this indicate, according to Dr.
Dobson, powers of swimming, or at any rate a not very remote ancestry of
swimming creatures. It is purely insectivorous in diet.

_Erinaceus_, including the Hedgehogs, is a widely distributed
genus--Palaearctic, Oriental, and Ethiopian in range. There are about
twenty species. The familiar spines distinguish the Hedgehogs from their
allies, as also the fact that they possess but thirty-six teeth, the
formula being I 3/2 C 1/1 Pm 3/2 M 3/3. There are fifteen or fourteen ribs,
and the tail is very short, consisting of only twelve vertebrae. As in
_Gymnura_ there is no caecum. The upper canine has usually, as in other
Erinaceidae, two roots, but not in _E. europaeus_, which is one of the most
modified of Hedgehogs.

The Hedgehog is a more omnivorous creature than _Gymnura_. It eats not only
insects and slugs, but also chickens and young game birds, and lastly
vipers. Four, or in some cases as many as five or six, young are produced
at a birth; they are blind, with soft and flexible white spines. In hot and
dry weather Hedgehogs disappear; they come forth in rainy weather. The
English Hedgehog, as is well known, hibernates. The Indian species do not.
The Hedgehog is occasionally spineless, which condition may be regarded as
an atavistic reversion.[382]

The Hedgehog has acquired the reputation of carrying off apples transfixed
upon its spines. Blumenbach thus quaintly describes this and other habits
of the animal, whose English name he gives as "hedgidog": "Il se nourrit
des productions des deux règnes organisés, miaule comme un chat, et peut
avaler une quantité énorme de mouches cantharides. Il est certain qu'il
pique les fruits avec les épines de son dos, et les porte ainsi dans son
terrier."[383]

The Miocene _Palaeoerinaceus_ is so little different from _Erinaceus_ that
it is really hardly generically separable. _Erinaceus_ is therefore clearly
one of the oldest living genera of mammals.

_Necrogymnura_ of the same epoch and the same beds (Quercy Phosphorites) is
doubtless an ancestral form. The palate is {511} perforated as in
_Erinaceus_ (it is not so in _Gymnura_ and _Hylomys_), but on the whole it
comes nearest to _Hylomys_.

FAM. 2. TUPAIIDAE.--This family contains the genera _Tupaia_ and
_Ptilocercus_. _Tupaia_ is Oriental in range, extending as far east as
Borneo. There are a dozen or so of species, which are generally arboreal
and have the outward aspect of Squirrels. It has been suggested that this
is a case of mimicry, the animal gaining some advantage by its likeness to
the Rodent. The name Tupaia, it should be added, means Squirrel, and the
long-nosed Squirrel, _Sciurus laticaudatus_, is so extraordinarily like it
that "one has to look at the teeth" to distinguish them. Moreover this
Squirrel, like some Tupaias, lives largely on the ground among fallen logs.
_Tupaia_ resembles a Lemur in the complete orbit. The dental formula is
I 2/3 C 1/1 Pm 3/3 M 3/3 = 38. The sublingua, too, is stated by Garrod to
be like that of _Chiromys_. There is a minute caecum in _T. belangeri_,
none in _T. tana_.

_Ptilocercus_[384] has a pen-like posterior portion to the tail, a
modification which is found in other groups of animals. The tail of certain
Phalangers, for instance, shows this same modification. The rest of the
tail is scaly. The animal, as was pointed out by Dr. Gray,[385] looks very
much like a Phalanger. The orbit is entire as in _Tupaia_. The fingers and
toes are five. The one species, called after Sir Hugh Low, G.C.M.G., _P.
lowi_, is a Bornean animal.

FAM. 3. CENTETIDAE.--This family is entirely confined to the Island of
Madagascar. It includes some seven genera. The best-known genus is
_Centetes_. _C. ecaudatus_, the Tanrec, Tenrec, or Tendrac, is an animal a
foot or so in length, without a tail, and with forty-four teeth.[386] The
immature animal is so different from the parent as to appear quite a
different form. It has three narrow rows of spines along the back, which do
not wholly disappear until the permanent dentition has been acquired. Even
then the hairs are of a rather spiny character, particularly those upon the
back of the head, which are erected when the animal is {512} annoyed. The
Tanrec feeds mainly upon earthworms. It is "probably the most prolific of
all animals," since as many as twenty-one young are said to have been
brought forth at a birth. Some Opossums, however, have twenty-five teats.

[Illustration]

FIG. 248.--Skull of Tenrec. _Centetes ecaudatus._ _fr_, Frontal; _max_,
maxilla; _pa_, parietal; _p.max_, premaxilla; _sq_, squamosal. (After
Dobson.)

_Hemicentetes_[387] is a genus with two species. These have spines mixed
with the fur of the back. There is no caecum in this or in other
Centetidae. The teeth are forty in number, there being only three molars.

_Ericulus setosus_ is a small Insectivore, resembling externally a small
Hedgehog. It is covered with close-set spines which, unlike what is found
in _Erinaceus_, extend over the short tail. The total number of teeth is
thirty-six, the formula being I 2/2 C 1/1 Pm 3/3 M 3/3.

_Echinops_[388] is another spiny genus which is a stage in advance of
_Ericulus_, for still another molar has been lost, reducing the total
number of teeth to thirty-two. The dental formula is thus I 2/2 C 1/1
Pm 3/3 M 2/2. The zygomata are reduced to mere threads.

_Microgale_, a genus recently instituted by Mr. Thomas, is a small furry
Insectivore with a long tail, which is more than double the length of the
head and body. There are no less than forty-seven vertebrae in the tail,
which is relatively longer than that of any other mammal.

_Limnogale_, discovered by Forsyth Major, is an aquatic genus, also furry
and not spiny, which has departed from the Centetid type and taken to an
aquatic life. The single species, {513} _L. mergulus_, is about the size of
_Mus rattus_; it has webbed toes and a powerful laterally-compressed tail.
Clavicles are present, which is not the case with _Potamogale_.

_Oryzoryctes_ is a Mole-like Centetid. It has fossorial fore-limbs, but a
fairly long tail. This genus is furry like the last two. It is said to
burrow in the rice-fields and to do much harm. The teeth are forty in
number, three incisors and three molars in each half of each jaw.

FAM. 4. POTAMOGALIDAE.--This family contains two genera, _Potamogale_ and
_Geogale_.

_Potamogale velox_ is a West African animal, which though an Insectivore
has the habits of an Otter. It is "somewhat larger than a stoat." The upper
surface of the body is dark brown, the belly brownish yellow. It has a flat
head and a long tail like the Stoat, but the tail is laterally compressed
and very thick. The eyes are very small; the nostril has valves. The toes
are not webbed; but the second and third toes are united for the whole
length of their first phalanges. Along the outer side of the foot is a thin
extension of the integument. In swimming the feet are drawn up along the
body, hence webbing would be of no use; but the thin flattening prevents
the edge of the foot from acting as a hindrance to the motion of the
animal. M. du Chaillu describes it as catching fish, which it pursues with
extreme rapidity in the clear mountain streams it frequents; but Dr.
Dobson, remarking that no stomachs have been examined, thinks that water
insects are more probably its prey. It is not known whether the animal
possesses a caecum. The tooth formula[389] is I 3/3 C 1/1 Pm 3/3 M 3/3. The
animal is exceptional among the Insectivora in having no clavicles.[390]
There are sixteen ribs; there is no zygomatic arch, and the pterygoids
converge posteriorly.

_Geogale_, with one species, _G. aurita_, is a small representative of this
family from Madagascar. It has only thirty-four teeth. When better known it
may be necessary, thinks Mr. Lydekker, to make this animal the type of a
separate family. The tibia and fibula are distinct, not confluent with one
another as in _Potamogale_.

FAM. 5. SOLENODONTIDAE.--This family contains but a single genus. {514}

_Solenodon._ This genus, including two species, one from Cuba, the other
from Hayti, was at one time referred to the Centetidae. It offers, however,
numerous points of difference from the members of that family with some
general points of agreement. Possibly its isolation in the two West Indian
islands mentioned is comparable to the isolation of the Centetidae in
Madagascar; they are both survivors of an ancient group of Insectivores
extinct elsewhere. _Solenodon_ has nearly the complete dentition. It has
lost only one premolar, and has therefore forty teeth in all. The formula
is thus I 3/3 C 1/1 Pm 3/3 M 3/3. It also differs from the Centetidae in
having only two inguinal mammae instead of both inguinal and thoracic; the
penis of the male does not project from a cloaca, but lies forward. On the
other hand, the molars have their cusps arranged in the [391]-fashion of
the Centetidae, a fact, however, which, in the opinion of some, merely
points to an ancient trituberculism not indicative of special affinity. It
has, moreover, no zygoma in the skull, and there is no caecum. Dr. Dobson
has furthermore tabulated a number of differences in muscular anatomy
between the two families. _Solenodon_ has a long naked tail. The snout,
always developed in Insectivores, is extraordinarily long in this genus. It
is a furry, not a spiny animal. _S. cubanus_ is liable to fits of rage when
irritated, a feature which it has in common with Shrews and Moles; it is
also stated to have the ostrich-like way of concealing its head in a
crevice, "apparently thinking itself then secure." But nothing is known of
the genus in a wild state.

FAM. 6. CHRYSOCHLORIDAE.--This family contains only the genus
_Chrysochloris_, comprising some five species, all natives of Africa south
of the equator. The scientific name of the genus, and also the vernacular
name Cape Golden Mole, are derived from the beautiful iridescent hairs
which are intermingled with softer and non-iridescent fur. _Chrysochloris_
has [392]-shaped cusped teeth like those that are possessed by the
Centetidae and Solenodontidae. In the skull as in the Macroscelidae, etc.,
but not in the Centetidae, there are complete zygomata. They are Moles in
habit, and the eyes are covered with skin; the ears, moreover, have no
conches. The teeth are forty or thirty-six in number, the reduction being
caused by the losing of a molar in those forms which possess the smaller
number.[393] It is interesting to notice that the {515} adaptation to a
digging life is brought about in quite a different way from that of the
true Moles (_Talpa_). In the latter the fore-limbs are changed in position
by the elongation of the manubrium sterni, carrying with it the clavicles,
which are extraordinarily shortened (Fig. 251). In _Chrysochloris_, on the
other hand, the same need (_i.e._ that the limbs project as little as
possible from the sides of the body, while the length of the limbs is
retained, and the leverage of the muscles unaffected) is provided for by a
hollowing out of the walls of the thorax, the ribs and the sternum being
here convex inwards. The sternum and the clavicles are not modified. The
tibia and fibula are ankylosed below. In the manus, moreover, there are but
four digits, of which the two middle ones are greatly enlarged. In the
Moles there are five fingers, and all are enlarged; there is, too, a great
radial sesamoid bone, which is as good as a sixth finger (which, indeed, it
is considered to be, in common with similar structures in other animals, by
some anatomists). The foot has only four toes.

[Illustration]

FIG. 249.--Golden Mole. _Chrysochloris trevelyani._ A, Lower surface of
fore-foot. × ½. (After Günther.)

FAM. 7. MACROSCELIDAE.[394]--This family contains three genera, all of them
African in range, and mainly Ethiopian.

_Macroscelides_, the Elephant Shrews, are jumping creatures of Shrew-like
appearance, combined with a Marsupial look. Both radius and ulna, and tibia
and fibula, are ankylosed. There {516} are five fingers and toes. There is
a caecum as in but few Insectivores. The tooth formula, as revised by
Thomas,[395] is I 3/3 C 1/1 Pm 4/4 M 2/(2 or 3), the total number being
thus forty or forty-two. There are several species of this genus.

[Illustration]

FIG. 250.--_Rhynchocyon chrysopygus._ × ¼. (After Günther.)

_Rhynchocyon_ and _Petrodromus_ differ from _Macroscelides_ in not having
such long hind-legs. The dental formula of the first is I (1 or 0)/3 C 1/1
Pm 4/4 M 2/2 = 34 or 36, of the latter I 3/3 C 1/1 Pm 4/4 M 2/2 = 40. In
_Petrodromus_ the toes are reduced to four; in _Rhynchocyon_ there are only
four digits in the manus as well as in the pes. This animal, as its name
implies, has a longish proboscis, which can be bent, and is really very
like a miniature Elephant's trunk, and also like that of the Desman
(_Myogale_). It has thirteen pairs of ribs, and a well-developed caecum.
Dr. Günther has pointed out that in _Petrodromus tetradactylus_ the hairs
of the lower part of the tail are stiff elastic bristles 5 mm. long, with a
swelling at the free tip. The use of this singular modification is not at
all apparent. _Pseudorhynchocyon_, of European Oligocene, is believed to be
related to this family.

[Illustration]

[Illustration]

FIG. 251.--Sternum and sternal ribs of the Common Mole (_Talpa europaea_),
with the clavicles (_cl_) and humeri (_H_); _M_, Manubrium sterni. Nat.
size. (From Flower's _Osteology_.)

FIG. 252.--Bones of fore-arm and manus of Mole (_Talpa europaea_). × 2.
_C_, Cuneiform; _ce_, centrale; _l_, lunar; _m_, magnum; _p_, pisiform;
_R_, radius; _rs_, radial sesamoid (falciform); _s_, scaphoid; _td_,
trapezoid; _tm_, trapezium; _U_, ulna; _u_, unciform; _I-V_, the digits.
(From Flower's _Osteology_.)

FAM. 8. TALPIDAE.--This family is confined to the Palaearctic and Nearctic
regions, or practically so, being fairly equally {517} distributed as
regards genera; a Mole just gets over the boundary into the Oriental
region. The genus _Talpa_ is entirely Old World in range, and includes
several species, of which the Common Mole, _T. europaea_, is the best
known. There are forty teeth, one of the molars of the full mammalian
dentition not being represented. In the milk dentition there is an
additional premolar, not represented by a successor in the permanent
dentition. The formula is thus I 3/3 C 1/1 Pm 4/4 M 3/3. There are no
external ears, and the eyes are rudimentary; the soft silky fur is familiar
to everybody. The sternum has a strong crest, associated with a powerful
development of the pectoral muscles, so necessary to a burrowing animal.
The animal, it is hardly necessary to state, lives underground in burrows
excavated by itself, which have not, it has been stated, the elaborate and,
it appears, fanciful shape assigned to them by many writers. At times Moles
appear above ground. {518} Their principal food consists of earthworms, and
it may not be out of place to quote Topsell's quaint account of their
pursuit of the annelids: "When the wormes are followed by molds (for by
digging and heaving they foreknow their owne perdition) they fly to the
superficies and very toppe of the earth, the silly beast knowing that the
molde, their adversary, dare not followe them into the light, so that their
wit in flying their enemy is greater than in turning againe when they are
troade upon." It has lately been said[396] that Moles store up earthworms
for consumption during the winter, biting off their heads to prevent their
crawling away.

_Scalops_, an American genus, is a Mole-like creature of largely aquatic
habits, as its webbed hind-feet show; it has a short, naked tail.
Apparently, like the Shrews, it has no lower canines.

_Condylura_, another American genus, is called the Star-nosed Mole on
account of a curious radiating structure at the end of the snout.

_Myogale_, the Desman, is still more aquatic in habit, and connects the
Moles with the Shrews, though, as in many of the former, it has lower
canines. It has webbed hind-feet and a long tail. One species occurs in the
Pyrenees, the other in Russia. A few other genera (_Urotrichus_,
_Uropsilus_, _Scaptonyx_, _Dymecodon_, _Scapasius_, _Perascalops_) belong
to the same family.

FAM. 9. SORICIDAE.--The true Shrews have a much wider range than other
families of the present order. In the Palaearctic region are found _Sorex_,
_Crossopus_, _Crocidura_, _Nectogale_, _Chimarrogale_. The first is also
Nearctic, and reaches Central America. In the Ethiopian region is the
single peculiar genus _Myosorex_, but _Crocidura_ occurs there also.
_Blarina_ and _Notiosorex_ are "Sonoran" in range; _Soriculus_ Oriental.
_Crocidura_, _Anurosorex_, and _Chimarrogale_ also enter this region.
_Sorex_ has teeth tipped with reddish colour, its dental formula being,
according to Mr. Woodward's recent researches, I 3/(2 or 3) C 1/0 Pm 3/1
M 3/3 = 32 or 34.

As compared with other Insectivores, therefore, the most remarkable fact
found throughout the family is the absence of the lower canines. In
addition to this the genus may be known--the family indeed--by the large
size of the first pair of incisors. In the above formula it is possible,
thinks Mr. Woodward, that there may be errors; he is not certain whether
the supposed {519} upper canine may not be a fourth incisor, and whether
the first premolar may not be really the canine. Another peculiar feature
about the dentition of _Sorex_ is the suppression of the teeth of the milk
dentition, which are functionless, and probably uncalcified. The genus
_Sorex_ is terrestrial. The tail is long and covered with hairs. There are
two species in this country, _S. vulgaris_ and _S. minutus_. The former is
the Shrew of legend and superstition; and it is no doubt the species that
has lent its name to the more untameable members of the softer sex, though
it is the males which are especially pugnacious. As to legend, everybody
has heard of the shrew ash whose leaves, after a Shrew has been inserted
living into a hole cleft in the tree, are a specific for diseases of
cattle, caused by the Shrew itself creeping over them.

The Rev. Edward Topsell, author of _The Historie of Four-footed Beastes_,
who defends his veracity by asserting that he does not write "for the rude
and vulgar sort, who being utterly ignorant of the operation of learning,
do presently condemne al strange things," says of the Shrew that "it is a
ravening beast, feigning itself gentle and tame, but, being touched, it
biteth deep and poysoneth deadly. It beareth a cruel minde, desiring to
hurt anything, neither is there any creature that it loveth, or it loveth
him, because it is feared of all." It is probable that all this rustic
feeling is due to the powerful effluvium which the Shrew undoubtedly emits.

_S. minutus_ has the distinction of being the smallest British mammal; it
is scarcer than the last. This form is found upon the Alps, as is also the
peculiarly Alpine species _S. alpinus_, which inhabits the Alps, Pyrenees,
Carpathians, and the Hartz.

_Crossopus fodiens_, the Water Shrew, has also brown-stained teeth. It is
not uncommon in this country, and lives in burrows excavated by the sides
of the streams which it affects.

Besides these two genera, _Soriculus_, _Blarina_, and _Notiosorex_ have
red-tipped teeth. In _Crocidura_, _Myosorex_, _Diplomesodon_, _Anurosorex_,
_Chimarrogale_, and _Nectogale_ the teeth are white-tipped. These are all
the genera of the family allowed by the late Dr. Dobson in a review of that
family.[397]

_Chimarrogale_ and _Nectogale_ are aquatic genera. The former {520}
consists of a Himalayan and Bornean, and of a Japanese species, which have
not webbed feet, but have a tail with a fringe of elongated hairs.

_Nectogale elegans_ is one of the characteristic animals of the Thibetan
plateau. It has webbed feet. The teeth are as in _Chimarrogale_ I 3/2 C 1/0
Pm 1/1 M 3/3.

The other genera are terrestrial in habit.

SUB-ORDER 2. DERMOPTERA.

[Illustration]

FIG. 253.--_Galeopithecus volans._ × 1/3. (After Vogt and Specht.)

The family GALEOPITHECIDAE contains but one genus, which has been at times
referred to the Lemurs, to the Bats, or has been made the type of a special
order of mammals. It is better to regard it as an aberrant Insectivore--so
different indeed from other forms that it requires a special sub-order for
its reception. {521}

_Galeopithecus_[398] inhabits the Oriental region. It is a larger animal
than any other Insectivore, about the size of a Cat, and has a patagium
extending between the neck and the fore-limb, between the fore-limb and the
hind-limb, and between the hind-limb and the tail. This patagium is
abundantly supplied with musculature, but the fingers are not elongated as
in the Bats for its support. In the degree of its development, however, the
patagium of this creature is midway between that of _Sciuropterus_ on the
one hand, and the Bats on the other. It presents many remarkable features
in its organisation. The brain is like that of the Insectivora in the
exposure of the corpora quadrigemina by the slight extension backward of
the cerebral hemispheres; but its upper surface is marked by two
longitudinal furrows on each side, a state of affairs (in combination)
which is unparalleled among the Mammalia. The teeth are peculiar by reason
of the singular "comb-like" structure of the lower incisors. This, however,
is an exaggeration of what is to be found in _Rhynchocyon_ and
_Petrodromus_, while the same style of tooth, though not so highly
developed, characterises certain Bats. The Tupaiidae and certain Lemurs
show what Dr. Leche regards as the beginning of the same thing. As in
_Tupaia_ also there is an indication of the characteristically Lemurine
sublingua. The stomach is more specialised than in other Insectivores, the
pyloric region being extended as a narrowish tube. There is a caecum. A
peculiarity of the intestinal tract is that the large intestine is longer
than the small.

ORDER XII. CHIROPTERA.

We may thus define the Bats:--Flying mammals, with the phalanges of the
four digits of the hand following the pollex greatly elongated, and
supporting between themselves and the hind-limbs and tail a thin
integumental membrane, which forms the wing. The radius is long and curved;
the ulna rudimentary. The knee is directed backwards, owing to the rotation
of the limb outward by the wing membrane. From the inner side of the
ankle-joint arises a cartilaginous process, the calcar, which supports the
interfemoral part of the wing {522} membrane. The mammae are thoracic; the
placenta discoidal and deciduate. The cerebral hemispheres, which are
smooth, do not extend over the cerebellum.

[Illustration]

FIG. 254.--Barbastelle. _Synotus barbastellus._ × ½. (After Vogt and
Specht.)

This large order of mammals was once placed with the Primates. There is no
doubt, however, that they form a perfectly distinct order; no knowledge of
fossil forms in any way bridges over the gap which distinguishes them from
the highest mammals. The most salient feature in their organisation is
clearly the wings. These consist of membrane, an expansion of the
integument, provided with nerves, blood-vessels, etc., which mainly lie
stretched between the digits 2 to 5. These digits themselves, which are
enormously elongated, act like the ribs of an umbrella, and when the wing
is folded they come into contact. Besides this part of the flying apparatus
there is a tract of membrane lying in front of the arm, which corresponds
to the wing membrane of the bird, but which in the Bats takes quite a
subordinate place. In the bird, on the other hand, there is a metapatagium,
which is the main part of the wing of the Bat. It seems just possible that
in _Archaeopteryx_ the metapatagium was more Bat-like. Furthermore, a
steering membrane, like that which fringes the tail in some Pterosaurians,
lies interfemorally in Bats, and includes the whole or a part of the tail.
The pollex takes no share in the wing, but projects, strongly armed with a
claw, from the upper margin.

The bones of this order of mammals are slender and marrowy; they are thus
light, and subserve the function of flight. A most remarkable feature among
the external characters of the Bat tribe is the extraordinary and often
highly complicated membranes which surround the nostrils. These are at
least often {523} more strongly developed in males than in females, and may
perhaps be partly relegated to the category of secondary sexual characters.
But it seems that they have also an important tactile function, and enable
the creatures to fly without touching bodies which intrude themselves upon
their way. The ears, too, are frequently very large, and it may be supposed
that the sense of hearing is correspondingly acute. In the common
Long-eared Bat of this country, the ears are not greatly inferior in length
to the head and body of the animal combined. The ears are of every variety
of shape, and offer characters which are valuable in the systematic
arrangement of the members of the order.

[Illustration]

FIG. 255.--Skeleton of Flying Fox. _Pteropus jubatus._ × 1/8. (After de
Blainville.)

In the skull of Bats there is very rarely a complete separation between the
orbital and temporal fossae; the lachrymal duct is outside the orbit. The
tympanics are annular, and in a rudimentary condition. The centra {524} of
the vertebrae tend to become ankylosed in old individuals; the caudals have
no processes, but are like those quite at the end of the series in
long-tailed animals. The sternum is keeled for the better attachment of the
pectoral muscles, the chief muscles of flight. The ribs, which are much
flattened, are occasionally ankylosed together by their margins. There is a
well-developed clavicle. In the carpus the scaphoid, lunar, and cuneiform
are all fused together. In the hind-limb the fibula is rarely fully
developed.

The Bats are divisible into two primary groups, which are those of the
Megachiroptera and the Microchiroptera.

SUB-ORDER 1. MEGACHIROPTERA.

[Illustration]

FIG. 256.--Skull of _Pteropus fuscus_. × 3/2. (After de Blainville.)

The PTEROPODIDAE are frugivorous Bats, usually of large size. The chief
distinguishing feature is the fact that the molars are not tubercular, but
marked with a longitudinal furrow, which is, however, concealed in the
genus _Pteralopex_ by cusps. The palate is continued back behind the
molars. The index finger has three phalanges, and is usually clawed. The
ears are oval, and the two edges are in contact at the base of the ear. The
tail, if present, has nothing to do with the interfemoral membrane. This
group is entirely Old World in range. The genus _Pteropus_ embraces the
creatures known as Flying Foxes. They are the largest forms in the
sub-order, sometimes having an expanse of wing of 5 feet (this is the case
with _P. edulis_). The muzzle is long, and the face therefore "foxy" in
appearance. {525} The inner margin of the nostrils projects, a preparation
for the tubular nostrils of _Harpyia_. The tail is absent. The premolars
are three and the molars two. The pyloric region of the stomach is extended
and twisted upon itself. Of this genus there are nearly sixty species,
extending from Madagascar to Queensland. Thirty species inhabit the
Australian, twenty the Oriental region. Madagascar has seven, and one
species just enters the Palaearctic. The occurrence of this genus in India
and in Madagascar is one of those facts which favour the view supported, on
these and other grounds, by Dr. Dobson and Dr. Blanford that a connexion
between India and Madagascar must once have existed; for these slow-flying
creatures could hardly be believed capable of traversing vast stretches of
ocean by their unaided efforts.[399]

[Illustration]

FIG. 257.--Flying Fox. _Pteropus poliocephalus._ × 1/3.

_Pteropus_ is represented in the Ethiopian region by the allied genus
_Epomophorus_. Of this there are perhaps a dozen species. The teeth are
reduced to two premolars in the upper jaw, {526} three remaining below;
while there is but one molar in each upper jaw, and two in each lower. Dr.
Dobson has studied the structure of the remarkable pharyngeal sacs which
exist in the neck of the male, and are capable of inflation.

_Pteralopex_ of the Solomon Islands has shorter ears than have many
_Pteropus_, otherwise its external characters are the same. As in _Pteropus
nicobaricus_, this genus has the orbits shut off by a bony ring, an
extremely rare phenomenon in Bats. The canines have two cusps. The
characters of the grinding teeth have already been mentioned. It is
uncertain whether the only species of this genus, _P. atrata_, is, or is
not, a vegetable feeder. _Harpyia_ has shortish ears and extraordinarily
prolonged and tubular nostrils. There is a hint of the accessory cusp to
the canines mentioned above in _Pteralopex_. The incisors are reduced to
one on each upper jaw, and none below. _Cynopterus_ has also often
bituberculate canines. It is an Oriental genus with several species.

_Nesonycteris_, with one species from the Solomon Islands, _N. woodfordi_,
has the dental formula I 2/1 C 1/1 Pm 3/3 M 2/3. The index finger has no
claw; the tail is absent. The premaxillae are separated anteriorly.

_Eonycteris_, with a single cave-dwelling species from Burmah, _E.
spelaea_, has also no claw upon the index; the tooth formula is fuller by
reason of the presence of an additional incisor below. The tongue is very
long and is armed with papillae. There is a short but distinct tail.

_Notopteris_, from New Guinea and the Fiji Islands, is distinguished from
the related genera by its long tail.

The remaining genera of Fruit Bats are _Boneia_, _Harpyionycteris_,
_Cephalotes_, _Callinycteris_, and _Macroglossus_, from the Oriental
region, and _Scotonycteris_, _Liponyx_, and _Megaloglossus_ from the
Ethiopian region; finally, there is the Australian _Melonycteris_.

SUB-ORDER 2. MICROCHIROPTERA.

The members of this sub-order are mostly insectivorous though occasionally
"frugivorous or sanguivorous" Bats. The molars are multicuspid with sharp
cusps. The palate is not continued back behind the last molar. The second
finger has but one phalanx, or {527} none; occasionally there are two. It
has no claw. The ear has its two sides separate from their point of origin
upon the head. The group is of Old-World distribution.

FAM. 1. RHINOLOPHIDAE.--The Bats of this family possess the leafy
outgrowths around the nostrils. The ears are large, but have no tragus. The
index finger has no phalanx at all. The premaxillary bones are quite
rudimentary, and are suspended from the nasal cartilages. In addition to
the pectoral mammae they have two teat-like processes situated abdominally.
The tail is long, and extends to the end of the interfemoral membrane.

The genus _Rhinolophus_ has a large nose leaf, and an antitragus to the
ear. The first toe has two joints, the remaining toes have three joints
each. The dentition is I 1/2 C 1/1 Pm 2/3 M 3/3. There are nearly thirty
species of the genus, which are restricted to the Old World. Two species
occur in this country, viz. _R. ferrum equinum_, the Great Horse-shoe Bat,
and the Lesser Horse-shoe Bat, _R. hipposiderus_. The name is of course
derived from the shape of the nose leaf.

The genus _Hipposiderus_ and some allied forms are placed away from
_Rhinolophus_ and its immediate allies in a sub-family _Hipposiderinae_.
The type genus _Hipposiderus_, or, as it ought apparently to be called,
_Phyllorhina_, is Old World in range, like all the other members of the
family.

The nose leaf is complicated, and there are only two phalanges in all the
toes; there is no antitragus to the ear. A curious feature in the osteology
of the genus, and indeed of the sub-family, is the fact that the
ileo-pectineal process is connected with the ilium by a bony bridge; this
arrangement is unique among mammals.

The genus _Anthops_, only known from the Solomon Islands, and represented
there by but a single species (_A. ornatus_), has an extraordinarily
complicated nose leaf. The tail, like that of the Oriental _Coelops_,
likewise represented by a single species (_C. frithii_), is rudimentary.

_Triaenops_, Ethiopian and Malagasy, has, like the Australian
_Rhinonycteris_, a well-developed tail. _Triaenops_ has also a
highly-complicated nose leaf.

FAM. 2. NYCTERIDAE.--This family is to be distinguished from the
Rhinolophidae by the fact that the ear has a small tragus, and by the small
and cartilaginous premaxillae. In addition to {528} these two characters it
may be added that the nose leaf is well developed, but is not so
complicated as in the last family. The type genus _Nycteris_ is Ethiopian
and Oriental, nine species being African, and only one, _N. javanica_,
being, as the specific name denotes, from the East. _Megaderma_ is to be
distinguished by the loss of the upper incisors. There is no tail, and the
ears are particularly large. They are carnivorous Bats, and _M. lyra_,
called the "Indian Vampire Bat," chiefly affects frogs as an article of
diet.

FAM. 3. VESPERTILIONIDAE.--This family has not the nose leaf of other
families. The apertures of the nostrils are simple, round, or crescentic
apertures. The ear has a tragus, and the tail is not produced to any great
degree behind the interfemoral membrane. There are two phalanges to the
index digit.

This family in numbers of species is vastly in excess of any other family
of Bats. The most recent estimate, that of P. L. and W. L. Sclater, allows
190. But the generic types are by no means so numerous as in the
Phyllostomatidae. This is a significant fact when we reflect upon the
geographical range of the two families. The Vespertilionidae range over the
whole earth, while the Phyllostomatidae are practically limited to the
South American continent, only just getting into the Nearctic region. They
inhabit, therefore, a more restricted area, and, in consequence of
competition, have specialised more freely than the widely-spread and
therefore not crowded Vespertilionidae.

The genus _Vesperugo_ is by far the largest genus of this family, embracing
no less than seventy species. The tail is shorter than the head and body
together; the ears are separate, and moderate or short in size; the tragus
is generally short and obtuse. The dentition is I 2, C 1, Pm 2 or 1, M 3.
It is a remarkable fact that this genus, unlike most Bats, produces two
young at a time. The genus is universal in range, and one species, the
Serotine Bat, known in this country, even ranges from the New World to the
Old; but with so small a creature the possibility of accidental
transportation by man must not be left out of sight. The British species
are--_V. serotinus_, the Serotine already mentioned; _V. discolor_, a
single example only of which has occurred, and may have been introduced;
_V. noctula_, the habits of which were described by Gilbert White; _V.
leisleri_; and the Pipistrelle, _V. pipistrellus_, which is the best-known
member of the genus in this country.

{529}

The genus _Vespertilio_ contains some forty-five species, and is world-wide
in range. It has one more premolar in the upper jaw than has _Vesperugo_.
There are no less than six British species, of which _V. murinus_ is the
largest species of Bat recorded from this country, but is not quite
certainly indigenous.

_Plecotus_ has very long ears. The dentition is I 2/3 C 1/1 Pm 2/3 M 3/3.
The tragus is very large. There are but two or possibly three species, of
which one is North American, and the other is the Long-eared Bat, _P.
auritus_, of this country, but ranging as far as India. The shrill voice,
inaudible to some ears, of this Bat has been heard _of_ by everybody.

_Synotus_ includes the British Barbastelle, _S. barbastellus_, as well as
an Eastern form. It differs from the last genus principally by the loss of
a lower premolar. The ears, too, are not so large. _Otonycteris_,
_Nyctophilus_, and _Antrozous_ are allied genera; the last is Californian,
the others Old-World forms.

_Kerivoula_ (or _Cerivoula_) has a long, pointed, narrow tragus. The tail
is as long as or longer than the head and body. The dentition is as in
_Vespertilio_; but the upper incisors are parallel instead of divergent as
in that genus. The brilliantly-coloured _K. picta_ is, on account of this
very fact, the best-known species. The name _Kerivoula_, a corruption of
the Cinghalese "Kehel vulha," signifies plantain bat. This Bat has been
described as looking, when disturbed in the daytime, more like a huge
butterfly than a Bat, which is naturally associated with sombre hues. Other
species occur in the Oriental, Australian, and Ethiopian regions.

_Miniopterus_ has a premolar less in the upper jaw; it has a long tail as
in the last genus. One species, _M. scheibersi_, has almost the widest
range of any Bat, it being found from South Europe to Africa, Asia,
Madagascar, and Australia.

_Natalus_ is an allied form from Tropical America and the West Indies. It
is chiefly to be separated from _Kerivoula_ by the short tragus to the ear.

_Thyroptera_ is also South American. It is distinguished by the curious
sucker-like discs upon the thumb and foot. These "resemble in miniature the
sucking cups of cuttle-fishes." The Madagascar genus, _Myxopoda_, with but
one species, has also an adhesive but horse-shoe-shaped pad upon the thumb
and foot.

_Scotophilus_ has shortish ears with a tapering tragus. The tail is shorter
than the head and body, and is nearly contained within {530} the
interfemoral membrane. The dentition is I 1/3 C 1/1 Pm 1/2 M 3/3, with
another upper incisor in the young. It is African, Asiatic, and Australian.

This genus appears to be connected with _Vesperugo_ by Mr. Dobson's
proposed genus, or sub-genus as it is generally held to be,
_Scotozous_.[400] The genus _Nycticejus_, founded for the inclusion of
_Scotozous dormeri_, an Indian species, should, according to Dr. Blanford,
replace on grounds of priority the name _Scotophilus_. But as this name
(_Nycticejus_) is one introduced by Rafinesque, whose work was so uncertain
and untrustworthy, it seems preferable to retain the better-known name of
_Scotophilus_, introduced by William Elford Leach.

The genus _Chalinolobus_[401] has short, broad ears with an expanded
tragus. A distinct fleshy lobule projects from the lower lip on either side
of the mouth. The tail is as long as the head and the body. The dental
formula is I 2/3 C 1/1 Pm 2/2 or 1/2 M 3/3. The genus occurs in Africa,
Australia, and New Zealand; but the African species, with diminished
premolars and pale coloration, have been distinguished as _Glauconycteris_.

FAM. 4. EMBALLONURIDAE.--The Bats belonging to this family have no nose
leaf. The tragus is present, but often very small. The ears in this family
are often united. There are two phalanges in the middle finger. The tail is
partly free, either perforating the interfemoral membrane and appearing
upon its upper surface, or prol