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THE MAMMALIA

EN THEIR

RELATION TO PRIMEVAL TIMES.

BY

OSCAR SCHMIDT

PROFESSOR IN THE UNIVERSITY OF STRASETJRO

WITH FIFTY-ONE WOODCUTS

NEW YORK
D. APPLETOX AND COMPANY

1, 3, AND 5 BOND STREET

1886

PEE FACE.

TN the Preface to the Third Edition of my
' Doctrine of Descent and Darwinism,' which ap-
peared in 1883, I quoted the opinion of a famous
lawyer as to the worthlessness of science, not
with the intention of refuting it, but gave it as
an example of the incredible naivete with which
eminent representatives of certain pronounced
religious tendencies confront the work and results
of natural science. Not long afterwards I was
asked by a well-known man whether my lectures
on zoology, at the university, treated of Darwinism
as well. What my answer was is kno\vn to all
those who have taken any interest in the ' theory
of descent.' To those who have an understanding
of the subject, and of the aims of a scientific
interpretation of the living world (which is, in

vi PREFACE

fact, the only one possible interpretation), I offer
the present work as a supplement. It will be
found to contain proofs of the necessity, the truth,
and the value of Darwinism as the foundation
for the theory of descent, within a limited field,
and is brought down to the most recent times.
Within these limits the work is complete in itself;
for although the student of natural history may
have become acquainted with interesting fragments
of the actual science, still the subject has not
before been presented in so comprehensive a
manner, or in so convenient a form.

Together with my special studies of the zoology
of the lower animals, I have for many years past
felt myself peculiarly attracted by the advance of
our knowledge of the Mammalia in their general
relation to palaeontology and anthropology.
From year to year I have followed this advance
with increased interest, and always with a view
to the principal questions connected with the
domain as a whole. Hence I venture to offer this
work to our younger and rising scientists as, I
trust, a suggestive introduction to that portion

PREFACE vii

of the animal kingdom which stands closest to
anthropology.

My materials have heen drawn from original
works, when and wherever they were within my
reach ; hence I never give extracts from extracts.
I take it for granted that my readers, if not already
in some measure acquainted with the forms and
mode of life of the Mammalia, have at hand some
such work as Brehm's ' Thierleben,' or Martin's
' Illustrirte Naturgeschichte der Thiere.' Books
such as these, which nowadays occupy a pro-
minent place in popular literature, make us
acquainted with facts ; but, with the exception
of C. Vogt's and Specht's works on the Mammalia,
they go no farther. Now, as the theory of descent
has shown, light and interpretation are shed upon
the Present by the Past ; and thus the history of
the development of animals, the history of the
earth and geography, are made to confirm one
another. In undertaking to give an introduction
to illustrate this, I must observe that it will be
possible only by overcoming a variety of difficul-
ties, by entering upon various apparently trifling

viii PREFACE

details — for instance, the construction of the teeth ;
and these must not be regarded in themselves as
merely amusing or entertaining, for, when brought
into connection, these details often open up the
most surprising and most wonderful prospects.
By these enquiries we do not indeed arrive at the
final cause of things, or at what the philosophers
call the Thing Itself, but from an insight into the
connection of the facts we obtain a higher
arrangement for those facts. They demand an
ever deeper penetration, and transport us into that
creative state of enthusiasm which, by being the
imaginative faculty of thinking-man, raises us
above those who remain standing amid their own
surroundings either in a state of blank amazement
or of dull enjoyment.

I am only following the usual custom by men-
tioning, in conclusion, the assistance I have re-
ceived from my daughter Johanna, to whose
experienced hand I owe a series of original draw-
ings, from which my illustrations have beem made.

OSCAR SCHMIDT.

STKASBURG : September, 1884.

CONTENTS.

PAQB

PEEFACE v

I. GENERAL INTRODUCTION.

1. THE POSITION OF MAMMALS IN THE ANIMAL KINGDOM. . 1

2. PHENOMENA OF CONVERGENCE ...... 14

3. THE DISTINCTIVE CHARACTERISTICS OF MAMMALS . . . 30

4. THE EXTENSION OF PAL;EONTOLOGICAL SCIENCE SINCE

CUVIER 45

5. THE STRATA OF THE TERTIARY FORMATION . . . . 77

II. SPECIAL COMPARISON OF THE LIVING
MAMMALS AND THEIR ANCESTORS.

1. THE MONOTREMA, CLOACAL OR FORKED ANIMALS . . 86

2. THE MARSUPIALS . . 93

3. THE EDENTATA, OR ANIMALS POOR IN TEETH . . .110

4. THE UNGULATA, OR HOOFED ANIMALS . . . . . 126

PAIR-HOOFED ANIMALS.

1. The Suids3, or Pigs 137

2. The Hippopotamus, or Kiver Horse . . . . 144

3. The Kuminants 150

4. Camels 154

5. Deer and their Kindred Forms .... 158

6. Hollow-horned Animals, Antelopes and Oxen . . 173

2

CONTENTS

ODD-HOOFED ANIMALS.

PA OR

1. Tapirs and Rhinoceros

2. The Equiilffi, or Horses 201

997

5. THE ELEPHANTS ...••••

6. THE SIRENIA., OR SEA-COWS 242

7. THE CETACEA, OR WHALES

8. THE CARNIVORA, OR FLESH-EATERS 259

9. THE SEALS . .... 287

10. THE INSECTIVORA, OR INSECT-EATERS. THE RODENTS.

THE BATS .

11. THE PBOSIMIJE, OR SEMI-APES. SIMISS, OR APES. THE

MAN OF THE FUTURE

INDEX 303

ILLUSTRATIONS.

FIO.

1. Eight hand of a River Tortoise . • • • • . 36

2. A. Lower jaw of Plagiaulax minor .... 99
B. Lower jaw of Plagiaulax medius 99

3. A. Lower jaw of Neoplagiaulax ..... 101
B. Lower jaw of Bettongia penicillata . . . . 101

4. Skull of Diprotodon australis ..... 103

5. Skull of the Wombat (Phascolarctus fuscus) . . . 105

6. Skull of Nototherium, side view ..... 105

7. Skull of Nototherium, front view . . . . . 106

8. Skull of the Giant Sloth 113

9. Skull of the Three-toed Sloth 115

10. Head of Glyptodon clavipes ...... 124

11. Left fore-foot of Anoplotherium . . . . . 129

12. Left fore-foot of the Peccary ..... 130

13. Coryphodon. Bight fore and hind foot . . . . 132

14. Coryphodon. Skull with brain ..... 134

15. A Tuberculate and a Crescentic Tooth . . . . 138

16. Eight fore-foot of a Pig 140

17. Palseochcerus typus, left upper jaw . . . . . 143

18. Second lower molar of the Hippopotamus, to the right 145

19. First upper molar of the Hippopotamus, to the right . 146

20. Hippopotamus, right fore-foot 147

21. I. Eight upper cheek-tooth of a Calf, before cutting the

gum 153

II. Eight cheek-tooth of a Calf, after cutting the gum,

artificially polished, from behind and the outside 153

22. Auchenia hesterna. Second left upper cheek-tooth . 157

xii ILLUSTRATIONS

FIG.

23. Prox furcatus. Left antler 100

24. A. Left fore-foot of the Ked Deer 102

B. Left fore -foot of the Roe . . . . .102

C. Second row of tarsals and metatarsals of Gelocus . 162

25. A. Left fore-foot of Hyremoschus aquaticus . . . 108
B. Left fore-foot of Hyopotamus 108

26. Skull of a Short-horned Bull 175

27. Skull of the Gazelle 176

28. Skull of the Bison americanus . . . . . 180

29. Skull of the Anoa 181

30. Skull of Cainotherium metopias 183

31. Skull of the Tapir (Tapirus americanus) . . . 191

32. Back molar, below to the left, of Lophiodon parisi-

ensis 192

33. Skull of Elasmotherium 197

34. A. Skull of Brontotherium ingens 199

B. The same from above with a drawing of the brain . 199

35. Palfflotherium. Hipparion. Horse . . . . 202

36. Left hind-foot of Anchitherium 204

37. Right upper cheek-tooth of the Horse . ., . . 209

38. Foot of the fossil Horses of North America . . . 213

39. Macrauchenia patagonia . . . . . . . 229

40. Polished molar of Mastodon angustidens . . . 232

41. Portion of a cheek-tooth of Mastodon elephantoides . 233

42. Portion of a cheek-tooth of the Mammoth, polished

sideways 235

43. Skull of Dinotherium giganteum 237

44. Skull of Dinoceras mirabile ..... 241

45. Skull of the Delphinus lagenorhynchus, Gray . . . 249

46. Right fore-leg of Delphinus delphis .... 250

47. Tooth of Squalodon 253

48. Teeth of the Fox 261

49. Lower jaw of Icticyon . . . . . . . 206

50. Skull of Tillotherium fodiens, from above . . . 286

51. Foetal teeth of the Greenland Seal 290

THE MAMMALIA

IN THEIE EELATION TO PRIMEVAL TIMES.

GENERAL INTRODUCTION.

THE POSITION OF THE MAMMALIA IN THE ANIMAL

KINGDOM.

IT has always been considered a matter of course
that the Mammalia stand at the head of the animal
kingdom. This has been the opinion of the multi-
tude who have not given any thought whatever to
the origin of living things ; also of those to whom
the ' idea of the creation,' or rather the empty word
creation, was, and still is, the one * comforter in
need ; ' and again also of the majority of our stu-
dents of modern biology, the advocates of the theory
of descent, and their few predecessors. This agree-
ment in the opinion expressed about the Mammalia
dates from the earliest times, and is founded upon

2 THE MAMMALIA.

the high estimation in which man holds himself,
an opinion which we meet with as uniformly. Man
finds himself bound by every fibre within the group
of the Mammalia ; and as soon as he makes him-
self the standard by which to measure the value
and the position of living creatures — and this he has
every reason to do within the circle of those he is
acquainted with — he cannot, when making a com-
parative survey, do otherwise than class them as
they always have been classed.

The very obvious fact of the close affinity of
the Mammalia with man, and the consequent neces-
sity for some systematic arrangement of them, leads
to the further observation that certain groups or
classes of animals resemble the Mammalia in the
main characteristics of form and structure more than
others. Nor has there ever been any doubt as to
this close * relationship.' Ever since the days of
Aristotle men have been agreed about the group
of the Vertebrates, and about the succession of
Fishes, Amphibians, Eeptiles, Birds and Mammals.
This order was naturally meant to express the gra-
dation of perfection, and always with the supposi-
tion of the ideal to be attained in man. Hence the
vertebrates, as a whole, formed the chief main divi-
sion, the highest type of the animal kingdom.

THEIK POSITION IN THE ANIMAL KINGDOM. 3

The position of the Mammalia in their connec-
tion with the other classes of vertebrates, and their
special relationship with one class of them — taking
the word relationship without its explanation hy
descent — rendered the old system extremely ohscure,
for the facts themselves spoke very imperfectly.
The anatomical resemblance is nowhere so absolutely
distinct that the descriptive method could point to
the bird, or to any one of the vertebrates, as show-
ing the closest and most numerous affinities with
the Mammalia. That animals of the frog species
and mammals should possess two condyles at the
back of the head as the first vertebras of the neck,
and that birds, like lizards and their relatives, had
only one, always seemed surprising to comparative
anatomists. Yet what was to be done with this
and other similar facts ? We know that since the
middle of the eighteenth century the idea of descent
and development flickered up here and there. But
the theory was unable to rise above the general
conception, and even in the present century its
importance was not felt by an anatomist who, in
my opinion, nevertheless possessed the clearest
ideas of the connection between the present and the
past. I refer to the elder <T Alton. Although his
interest in the subject was aroused by Goethe, it

4 THE MAMMALIA.

was Goethe again who is indebted to d' Alton for
some of his most frequently quoted opinions.
Goethe, in order, as it were, to keep off the profanum
vulgus, gives in a mystic form what d' Alton stated
unequivocally. D' Alton's famous work on skeletons
also induced Goethe to discuss the subject of adapt-
ability, and to maintain that adaptation was one
of the most important factors in producing new
forms. * The animal is formed by circumstances
for circumstances.'

The power of an organism to accommodate
itself to the place of its abode and food — which is
an undisputed phenomenon — must be all the more
striking the more complicated the structure of the
group of animals, and can therefore generally be
more easily verified in the case of the mammal,
even by the unpractised eye. As the mammal, in
the first place, endeavours to satisfy its need of
food, the variation called forth by the adaptation
directed towards this want is expressed at first by
its instruments of locomotion and mastication. It
may also be said that mammals give more proof of
the power of adaptation in the systematic arrange-
ment of their parts than most of the other classes
of animals, but we must not forget that this
arrangement of parts, in all classes of animals, is

THEIR POSITION IN THE ANIMAL KINGDOM. 5

almost exclusively the result of adaptation. The
power of the animal to move in accordance with
the peculiarity of the place of its abode, to secure
its food, and to rear its offspring, is in most cases
so perfect (if the imperfections are concealed) that
the real purpose would seem to be the harmony of
the surroundings and means of subsistence of the
organism. The scientific novice as well as the
dualistic philosopher finds ' a purpose in nature ' —
a common purpose of connected systems of organs
— even where the scientific inquirer sees a number
of imperfections, that might more consistently
with a ' purpose ' have been avoided had the
natura naturans wished to take a more direct road.
How precarious this idea of a ' purpose in nature '
is, as regards our own bodies, might, we think,
be felt with every cold in the head. It is only
when the adaptability has become an actual con-
dition that the result appears to be a preordained
purpose.

Those who regard the Mammalia as organisms
adapted for some special purpose, and exactly in
their place when and as we find them, are satis-
fied with a systernative manual on the subject.
But, we ask, is this kind of knowledge science ?
Does this knowledge give us any real understand-

6 THE MAMMALIA.

ing of the subject? Can those who know the
Mammalia of our day, in all the various phe-
nomena of their life and the differences in their
structure, be said to be fully enlightened as to the
causes and connection of all these facts ? As this
has generally been taken for granted, zoology has
hitherto been stigmatised by the senseless appella-
tion of * a descriptive science ; ' for, in fact, it was
not considered to possess the character of a science
that inquires into a causal connection. As if a
science could exist without having an observing as
well as a descriptive part !

The descriptive zoologist need not in any way
trouble himself or be astonished at anything.
When, however, he has to take into consideration
the scientific results of recent times, he will have
to pause before a series of specially striking phe-
nomena. This will happen, for instance, when he
is about to make a preliminary comparison of the
Mammalia with the rest of the Vertebrates, for he
will want transition forms between the former and
the latter. Buffon's opinion, that by carefully
observing two organisms, however different, an un-
interrupted series of transition forms will always
be found, did not long hold good in face of our
more strict systematic arrangement. The link

THEIR POSITION IN THE ANIMAL KINGDOM. 7

between the Mammalia and the rest of the verte-
brates has scarcely been looked for anywhere,
except among the birds, owing to the obviously
high degree of mental development attained by
certain members of this class, owing to the stronger
and more perfect circulation of their blood. But
neither Buffon or any other later comparative
anatomist has undertaken to give any specific proof
of this link, because, as was said above, other
circumstances pointed to a relationship with the
Amphibians.

It will not be necessary to make other vain
attempts to bridge over the gap between the
Mammalia and the other vertebrates of the present
day. It will even be shown that this difficulty is
not at all or but little removed by our present
knowledge of primeval times.

More striking still are the numerous isolated
forms within the class of the Mammalia themselves.
The best known example of this kind of an isolated
form of mammal is the horse and its relatives, the
genus Equus. The descriptive zoologist places it by
the side of the two-hoofed animals. Yet the differ-
ence between the one-toed horse and the two-toed
oxen and stags remains completely unexplained.
Besides this, the more perfect dentition of the horse

8 THE MAMMALIA.

stands in sharp contrast with the reduced dentition
of most of the ruminants, which lack the upper
incisors ; the only point of connection would seem
to be the camel, which again has a much fuller
dentition. Nevertheless, the horse remains a phe-
nomenon so peculiar within itself, that descriptive
zoology has always classed the genus Horse— which
is limited to a few species — in the order of the two-
hoofed animals, which contains a number of different
genera and several hundred species.

It is much the same with the perfectly unten-
able order of the many-hoofed or thick-skinned
animals, for it is made to comprise entirely different
members. What a peculiar form, for instance, we
have in the elephant among the thick-skinned
animals, or, indeed, among the whole class of
Mammalia: a strict vegetarian, and yet in every
respect an oddity among the plant-eaters. The
caps of horn, somewhat like nails, which cover
the points of his toes, can scarcely be called hoofs.
The form of his skull, his teeth and his trunk, in
like manner, separate him from all the other plant-
eaters in whose society he has figured since the
days of Linnaeus. But even among the rest of the
so-called many-hoofed animals there is no unity,
even according to the interpretation of a later,

THEIK POSITION IN THE ANIMAL KINGDOM. 9

post-Linnsean system ; for the various genera differ
more from one another in structure, feet and teeth,
than do the members of other orders. That the
pig shows more affinity with the rhinoceros or with
the hippopotamus than with the ox, is anything
but self-evident as soon as it is clearly perceived
that the connecting link cannot be in the number
of hoofs. "We may mention as isolated genera also
the camel, the giraffe, and the fingered-animals ;
and as isolated families all those animals which, on
account of their defective dental arrangement, may
be classed as animals poor in teeth (Edentata),
such as sloths, girdled animals, ant-eaters, and
scaled ant-eaters; for even as groups they show
among one another a want of harmony similar to
that of the heterogeneous divisions of the class of
the many-hoofed animals. If, further, we draw
attention to the contrast in which the Marsu-
pials stand to all the other orders of mammals,
while they differ very widely among themselves,
we shall have pointed out a large number of
phenomena that are wholly unintelligible by them-
selves.

In addition to this we meet with the many
geographical difficulties ; for instance, the geo-
graphical distribution of animals which, by itself,
3

10 THE MAMMALIA.

is inexplicable.1 Certainly all the phenomena here
referred to are intelligible when the supposition of
migration does not stumble upon contradictions
and surmountable obstacles, and when the capacity
of the organism to acclimatise itself — using the
word in its widest sense — is taken into account as
a long since established fact; but the question as
to the origin of species in general is left as a point
to be considered apart. Without doubt that which
tends to the widest distribution of an animal form
and to the intercourse between the most different
species, is the sea. Since recent scientific investi-
gations have made us as intimately acquainted
with the ocean-currents as with the systems of
rivers, with the range of cold currents and tongues
of water in the southern seas and conversely, and
has marked the different depths of the ocean
currents, and given us charts of the bottom of
the sea, with maps showing its elevations and
depressions — it would seem that, with an account
of the animals in the sea, the possibilities and
causes of their occurrence would likewise be ex-
hausted.

The state of the matter is very different -as
regards the distribution of animals on land, in

1 Wallace, The Geographical Distribution of Animals.

THEIR POSITION IN THE ANIMAL KINGDOM. 11

lakes and rivers. Of a large number of inland
lakes we know that it is only within a period
scarcely separable from the present that they have
become detached from the sea. A large portion of
the inhabitants of these lakes is accounted for by
this very fact. In regard to the rivers we have
here specially to consider fishes and mussels. Now
it is well known that a number of fishes— for
instance, the salmon, smelt, eel, and certain kinds
of plaice — spend their life partly in fresh and partly
in salt water, according to the season of the year,
for the sake of propagation ; and further, that they
can be transferred from the one to the other kind
of water without injury. Hence we may assume,
in the case of all purely fresh-water fishes and
mussels, that their progenitors could also at one
time live in either kind of water : we have thus a
perfectly satisfactory explanation of the occurrence
of the same genera, partly also of the same species,
in rivers situated very far apart. Examples of
this kind in the group of mammals are not fre-
quent, but instructive. The sea-cow, discovered
by Vogel in the Benue, is the only species of the
order of the Sirenia which, it would seem, has
never attained a fuller development, and — to use
an expression of Kiitimeyer's — has completely taken

12 THE MAMMALIA.

leave of the sea. On the other hand, the American
lamantin is still undergoing the transition, and
feels as comfortable in the sea as it does in the
lowest currents of large streams. The dugong of
Eastern Africa has, however, remained perfectly
faithful to its old, habitual element. An interest-
ing example of the occurrence of a mammal in an
inland lake is the dog-fish of the Caspian Sea. It
was, in fact, simply left there. That this large
sheet of water was at one time connected with the
sea is a long since established fact.

By this remark, and a return to the geological
past (even though it be to a most recent past), we
have again entered the only path which leads to
the understanding of all the geographical configu-
rations of the present, more particularly to the
distribution of the organisms, and above all to that
of the land animals. The difficulty of meeting
with closely related species, orders, and larger
groups, in regions lying far apart and separated
by high chains of mountains or impassable oceans,
has, since Buffon's days, been quietly settled with
the word ' vicariate,' which proves anything but a
true understanding of the matter. When it is said
that the Marsupials ' vicariate ' in Australia for the
other groups distributed on the other continents,

THEIR POSITION IN THE ANIMAL KINGDOM. 13

this expression denotes nothing but the bare fact,
nothing but the mere statement, that in America
we do not meet with the camel but with the llama,
which in a few main characteristics shows some
affinity with it. The one * vicariates ' for the
other. Why ? we ask. What is the meaning of
such ' vicariating ' ? We get no answer.

Now, in raising the study of zoology from the
stage of a mere descriptive method to the height
of a true science, we demand an explanation of
connections and agreements. Every endeavour
to comprehend the animal world, from a scientific
point of view, makes modern geology the basis of
its operations, and its testimony — which is of fifty
years' standing — is that the present condition
of the earth's surface, the distribution of land and
water, has proceeded from the most gradual and
primeval processes, except in cases of purely
locally interrupted transformations. Scientific
study must, secondly, accept the phenomenon of
the power of adaptability in organisms, that ver-
satility of the organs with which plants and
animals meet the variability of their external
circumstances, and adapt themselves to changes
that are taking place, by habit and by the gradual
changes of their own bodies which are connected

14 THE MAMMALIA.

with it. Whoever believes in the unity of the
human race must be a decided advocate of this
variability, even though it be but in the crude
notion of regarding the negroes as sun-burnt
white men, and the latter as bleached black men.
Those, however, who feel convinced of the contrary
maintain the variability to be the result of the un-
doubted mixing of the races and species.

If we look upon the dog as having been created,
then the assumption of an extraordinary capacity
of adaptation is unavoidable, but it is equally so
to those who see in the domestic dog a number
of different species of tamed jackals.

THE PHENOMENA OF CONVERGENCE.

Even Goethe early recognised the fact that ex-
ternal influences — ' the four elements ' — to which
the animal has to submit and to adapt itself for
the necessity of self-preservation, change the form
and mode of life to so great an extent that re-
semblances have been produced between creatures
wholly different at first. But Goethe did not give
unequivocal expression to this thought till d'Alton
had very clearly emphasised the transformation
and development of organisms, as the result of
'elementary conditions.' A number of Goethe's

PHENOMENA OF CONVERGENCE. 15

remarks, which are continually being quoted since
Haeckel's enthusiastic advocacy of Goethe as the
precursor of Darwin, are mere transcriptions of
passages from d' Alton.1 The phenomenon that
different animals, very divergent in their struc-
ture, and hence not related to one another, can,
when placed in the same circumstances, develop
certain similarities, did not escape his thoughtful
mind. He writes : ' The Eodents in form show
affinity with various orders ; the rat resembles
the beast of prey ; and the hare in its mode
of life and food, even in form and characteristics,
resembles the Kuminants.' This sentence Goethe

1 Goethe's poem, the MetamorpJiosis of Animals, where we
find the lines —

Hence, each form conditions the life and acts of the creature,
And each fashion of life, with reflex forcible action,
Works on the form ;

• ••»••*

Also hestimmt die Gestalt die Lebensweise des Thieres,
Und die Weise des Lebens, sie wirkt auf alle Gestalten
Machtig zuriick —

belongs to the year 1819. D'Alton, in his work on the Skeletons
of the Rodents in 1823, says : ' Thus it can no longer appear
doubtful that the tendency of development in the organism is as
dependent upon outward circumstances, as the mode of life of
animals is determined by their organisation.' This thought,
like others, is reproduced by Goethe when discussing this
classical work in 1824. In this ' intellectual discourse ' he may
have found to his great satisfaction what he had himself long
since perceived and pondered over.

16 THE MAMMALIA.

transcribes in his own way with a seemingly unim-
portant alteration, which, however, changes the
matter itself essentially. He says : ' However much
the form of the Kodent may vary to and fro,
apparently knowing no boundary, still in the end
it is found confined within the general animal
type, and must approximate either the one or the
other group of animals ; and thus it inclines both
to the beasts of prey as well as to Euminants, to
apes as well as to bats, and even to other inter-
mediate groups.'

These similarities and parallelisms did not
receive much attention until Darwin's day. Darwin
himself speaks of convergence only casually, and by
way of pointing out the great improbability of its
occurrence as the cause of agreements in organisms
not related by blood. But for the last ten years
or more, zoologists have so often been forced to
account for the existence of similarities and agree-
ments— not as inherited peculiarities of race, but
as transformations and assimilations, the result of
outward circumstances upon the same or similar
original forms — that this agency must be taken
into consideration, and will be specially necessary
in our present inquiry, for it seems to have played
no small part in the group of the Mammalia. A

PHENOMENA OF CONVERGENCE. 17

few remarks upon the origin of the idea of con-
vergence will, therefore, not be out of place.

As soon as the idea has been grasped that
mechanism governs an organism with the same
regularity as it does an inorganic body, the ques-
tion must naturally arise how far the living sub-
stratum can be influenced by outward circum-
stances, and how far the same results — independent
of one another — may be attained under the same
and similar conditions. The genius of Diderot
comprehended the problem in its widest applic-
ability. In a conversation with d'Alembert in 1769,
he makes the latter start the supposition that
after the destruction of all life by the extinction of
the sun, a repetition of the development of the
plants and animals that formerly existed would
recommence with the rekindling of the heavenly
body which diffuses force and life. For, he adds,
nothing else is conceivable but that the causes,
once again set in motion, should produce the same
effects as they had already done. According to the
Linnaean and Cuvier's interpretation of species,
this idea could scarcely expect to find acceptance,
and it is self-evident that any agreement was made
to rest upon the same origin of the individuals of
the species, and further upon the same fundamental

18 THE MAMMALIA.

form, that is, upon the inexplicable sovereignty of
the idea of type. Even though parallel groups —
such as the repetition of different orders of the
Mammalia within the group of Marsupials, the
repetition of the habitus of the Rodents in the
Insectivora — were observed and discussed, still the
contented zoologist did no more than enter these
observations into his book; and remarks such as
those made by Goethe and d' Alton remained with-
out result. What position Darwin took as regards
the idea of convergence, has already been stated.
His school, too, endeavoured at first to account for
the homologies exclusively by inheritance, and, on
the other hand, regarded the effects of adaptation
almost wholly as differentiation. Even that
extremely interesting adaptation as a means
of defence — mimicry — and, moreover, the ease
where the species in danger finds immunity and
protection in feigning a resemblance with the
species not endangered, did not lead to any
generalisation of the inquiry. Still, some striking
phenomena of convergence were observed, and
others that had long since been known, but not
carefully considered, were inquired into more
particularly. Among these is Fritz Miiller's
admirable analysis of the arrangements by which

PHENOMENA OF CONVERGENCE. 19

the land crabs of the most different families con-
verge in their mode of life and physiology of
breathing. The transition from life in water to
life on land has commenced in the one and the
other species, here and there, and they meet in the
most different stages of capacity for life on land ;
no form is so far changed that its relation to some
definite family is not unquestionably evident. The
transition from a life in water to one on land has
transformed both feet and gills, but has not gone so
far as to show agreement or apparent homology.
In this case of convergence the mode of life has
remained the same as that in which the Eodents
resemble the Insectivora and the Cetacea the
Sirenia. They were judged differently without
principle or consistency. The agreements in the
Insectivora and the Eodents had always been
considered as accidental and purely external,
whereas the Cetacea and Sirenia were classed
together in one order as close relatives.

We must here mention an attempt made by
Kolliker,1 an eminent German scientific man, to

1 Kolliker's Alcyonarien in the Abhandlungen der SencJcen-
bergischen naturforschenden Gesellschaft, vii., viii. Published
separately under the title of Morphologic- und Entivickelungs-
geschichte des Pennatulidenstammes nebst allgemeinen Betrach*
tuncjen zur Descendenzlelire. Frankfurt a.M., 1872.

20 THE MAMMALIA.

prove the theory of descent as improbable and un-
necessary, by assuming in its place a general law
of development by which the different species origi-
nated side by side without blood-relationship. His
fundamental idea, as he himself says, is that with
the first origin of organic matter and of organisms
a plan of development was also given, a whole
series of possibilities (by whom ? we ask), but that
various outward influences acted determinatively
upon individual development and produced a dis-
tinct character. That organic nature is the result
of some grand plan of development and of universal
laws, and that the explanation of the processes of
development is nothing more than that they take
place according to internal causes, according to
laws by which the organisms are most distinctly
forced to an ever higher form of development. In
like manner eggs and germ cells are said to pass
into new forms from internal causes : indepen-
dent, living, youthful forms are said to begin a
development different to the typical one, while out-
ward influences affect the process in various modi-
fying ways, and transformations ensue which,
although contained in the general plan, did not all
necessarily need to be fulfilled. Every different
species is said to have originated in this way by it-

PHENOMENA OF CONVERGENCE. 21

self: further, that it would even seem probable that
one and the same species appeared in different pedi-
grees ; for, owing to the unavoidable assumption of
universal laws of formation, it cannot be denied
that the same primary forms might, under certain
conditions, be able to lead to the same final form.
Where individual species have been found in places
widely separated, Kolliker even considers it more
appropriate to assume an independent origin for
them.

In the remarks just quoted there is clearly a
question about development, even of a plan of
development, but there is no mention whatever as
to how we are to conceive those laws and effects
which have produced the numerous branches of the
animal kingdom; for what are these internal causes
which so distinctly force things towards an ever
higher form of development ? Nothing is to be
gained from this idea, which scarcely deserves
the name of an hypothesis. It is a complete re-
habilitation of dualism and teleology. Kolliker's
supposition does certainly touch upon our present
views of convergence, but it goes no further ; for,
in the first place, it takes for granted the existence
of some plan which cannot be accurately defined,
a tendency — i.e. a purpose ; and, secondly, it does
4

22 THE MAMMALIA.

not consider the difficulties arising from the endless
recurrence of the agreement of thousands of cir-
cumstances which are necessary for the production
of a definite organism, but declares this highly
improbable combination to be a law. That a sea-
feather of the southern ocean should * originate '
spontaneously without ancestors, and be precisely
like an individual in the northern ocean, which
owes its existence to the same unknown processes
without ancestors, shows such a degree of improba-
bility that it amounts to an impossibility. It is, in
fact, as improbable as that Adam originated out of
a clod of earth. The prophecy that the whole
edifice of the Darwinians would collapse, while the
theory of a universal law of development (which
assumes a number of independent pedigrees as its
basis) would rise up triumphantly instead, has not
yet been fulfilled.

However, convergencies and repetitions have
been observed in abundance since then. In my
work on the Sponges, I have adduced special proofs
of how a series of convergencies — the formation of
water-channels, form and disposition of microscopic-
bits of skeleton and entire skeletons, root-like off-
shoots, tensions and other formations— which are
defensive arrangements against the intrusion of

PHENOMENA OF CONVERGENCE. 23

foreign bodies, in short, characteristics which would
seem to justify the conclusion of relationship, are
merely the result of mechanical contrivances, of
the effects of outward circumstances upon hetero-
geneous organisms.

That outward circumstances have co-operated
helpfully and determinatively in the development
of symmetrical animal forms, cannot be doubted
by any except those who cling to their belief in the
type theory. It follows from this that, to a certain
extent, all organs appearing in pairs owe their
origin to convergence. "We should further have to
weigh those circumstances where, in nearly related
organisms, the same organs vary on one side ; this,
for instance, occurs frequently in the pincers of the
Crustacea. It is only when starting from conver-
gencies of this kind — which may be called homceo-
genetic, and, according to general supposition, are,
as it were, self-evident — that we can pass on to
those phenomena to which the idea of approxima-
tion is specially applied in our day, the heteroge-
netic cases of convergence. A shell-less tropical
snail, Onchidium, has eyes on the numerous wart-
shaped protuberances on its back. Semper ] makes

1 Semper, Ueber Sehorgane vom Typus der Wirbelthieraugen
auf den Rticken von Schnecken. Wiesbaden, 1877.

24 THE MAMMALIA.

it appear extremely probable that these eyes — of
different species and individuals— originated inde-
pendently of one another. By connecting this
development with the general characteristics of the
cells of the upper skin and of the protoplasm, he
shows that this repeated formation of eyes must be
regarded as arising from a simple foundation. This
is one form of convergence, repetition in the indivi-
dual. The other is contained in the fact that the
eye of the onchidium shows an advance towards
the eye of the vertebrate, inasmuch as its structure
and the retina differ essentially from the eye of the
other molluscs.

A few years ago a great fuss was made about a
case of convergence which scarcely deserved this
name, and when inquired into dwindled down to
certain superficial resemblances, such as have been
observed times without number since we have had
descriptions of natural objects. I refer to the re-
semblance of certain primeval reptiles to mammals,
the so-called Theriodonta. The case was this.1 In
the Trias formation of the southern extremity of
Africa there were found, in addition to the colossal
plant-eating reptiles of the group Dinosauria, a
series of other animals, hitherto unknown, which,

1 Owen, Fossil Rcptilia of South Africa. London, 1876.

PHENOMENA OF CONVERGENCE. 25

upon the very first examination of the teeth, proved
to be flesh-eaters. Now the teeth of the modern
flesh-eaters are characterised by being definitely
separated, and by the peculiar formation of the
incisors, the canines, and the molars. The canines
above and below and on either side of the jaw are
powerful weapons, and admirable instruments for
tearing off flesh and for the gnawing and the
breaking up of bones. They separate the incisors
from the molars in a distinctive manner.

In the case of the above-mentioned South
African reptiles also, the teeth, which from their
position we know to have been incisors, are sepa-
rated from the molars by a large canine tooth. The
lower one rises in front of the upper one, yet when
the mouth is closed ifc lies close to the inside of the
upper jaw. The molars are certainly small and
cone-shaped ; however, when drawing a comparison
we can recall similar instances of this in seals.
Owen, to whom we owe the description of these, in
any case, very remarkable animals, also draws
attention to the formation of the upper part of the
arm, which, apart from the difference in the form-
ation of the extremity of the upper joint, shows an
approximation to the cat-type in the construction
of the extremity of the lower joint, for the ulna

26 THE MAMMALIA.

and the second bone of the lower arm — the radius.
Owen accordingly makes the names of the new
genera remind us of the dog, wolf, tiger, &c.,
Cynodracon, Lycosaurus, Tigrisuchus. He then
speaks of the importance of the discovery and says :
' If the gap in the series of animals between the
Mesozoic and Psychozoic air-breathers had not been
filled up otherwise than by reptiles, the remnant of
that class which has survived and reached our
times would have testified to the total loss of such
gains of organisation as had enriched the ancestors
and predecessors of modern tortoises, lizards, and
crocodiles.

' We know now that not one of these gains has
been lost, but has been handed on, continued and
advanced through a higher type of vertebrates, of
which type we trace the dawn back to the period
when reptiles were at their best — grandest in bulk,
most numerous in individuals, most varied in spe-
cies, best endowed with kinds and powers of loco-
motion, and with the instruments for obtaining
and dealing with both animal and vegetable food.

* Has the transference of structures, it may be
asked, from the reptilian to the mammalian type
been a seeming one, delusive, due to accidental
coincidence in animal species independently and

PHENOMENA OF CONVERGENCE. 27

thaumatogenously created ? Or was the transfer-
ence real, consequent on nomogeny, or the incoming
of species by secondary law, the mode and way of
operation of which we have still to learn ? Certain
it is that the lost reptilian structures specified, are
now manifested by quadrupeds with a higher con-
dition of cerebral, circulatory, respiratory, and legu-
mentary systems — a condition the acquisition of
which is unintelligible to the writer on either the
Lamarkian or the Darwinian hypothesis.'

It is unintelligible to us also, for we do not
in the slightest degree imagine that those coinci-
dences, which are neither great nor astonishing,
have to be understood by means of Darwin's hypo-
thesis. There is, in fact, no question whatever
about transferred conditions of organisation, for the
coincidence is confined to mere adaptations, and>
in part, very superficial ones ; adaptations which,
in some cases, are * intelligible ' without any diffi-
culty. With the help of our present prototypes
and the above fossil material, we can imagine all
kinds of substitutes for our wolves and the other
beasts of prey. It is extremely probable that many
of the earlier, and to us unknown mammals, in-
herited a uniform set of teeth (perhaps somewhat
like the dolphin's) direct from their ancestors of

28 1HE MAMMALIA.

the amphibian or reptile species. Now the fact
that direct descendants of reptiles, with a uniform
set of teeth, should acquire distinctive corner teeth
(canines) in consequence of their tearing their vic-
tims, as is the habit of beasts of prey, and that
certain mammals have acquired these teeth also,
owing to their having taken to flesh-eating, is a
convergence that can be most satisfactorily ex-
plained as the result of the same activity upon
similar or the same developments in the earlier
forms of teeth. It is, as we have already said,
a case of convergence of the most superficial kind.
Among living reptiles — in the Hatteria, Uromastix
spinipes, and also a species of agama — we meet
with advances towards the dentition of the Car-
nivora. But even when the canine is followed at
first by small pointed teeth, and then by broader
ones, there is nothing, either here or in the case of
the fossil African reptiles, that can be pointed out
as * peculiar molars with broad crowns ' (Wieders-
heim).

It is self-evident that given a like beginning
and like circumstances, we will more readily meet
with similar and the same phenomena than where
there was inequality to start with. In other
words homceogenetic convergences occur most fre-

PHENOMENA. OF CONVERGENCE. 29

quently. The Linnaean conception of things, to-
gether with the idea of type, and finally the move
recent idea of homology as agreement by reason
of derivation, have, however, been the cause that
approximations in general, especially within the
given ' natural group,' were more or less neglected,
or, at least, that merely surmised homologies-
sucli as the breathing apparatus of the lung-snails
— turned out to be convergencies. Within the
group of mammals we meet with a very evident
series of convergencies which have already been
spoken of above. Still, all circumstances con-
sidered, convergence can explain only the smallest
portion of the phenomena. That the Marsupials
should show agreements with certain orders of the
higher mammals is, at least, in part approxima-
tion. That they form an unity among one another
is another thing. Why are cats and dogs classed
together as beasts of prey ? Why are pigs, oxen,
and deer classed as hoofed-animals ? In short,
setting aside the above instances, in the other cases
of agreement convergence is improbable a priori,
and the explanation of all the other, the main por-
tion, must be looked for in the doctrine of descent.
It contains the greater amount of probability, a
probability which often borders upon certainty.

30 THE MAMMALIA.

And hence every class of the Mammalia of the
present day can be understood only from its con-
nection with its geological ancestors. But are we,
by admitting true agreement in organisms and their
parts, and by only allowing what is inherited to be
real honiologies, are we entering a domain wholly
distinct from that of convergence ? On the con-
trary. Inheritance is only a case of repetition
under the same conditions, a case of universal
law. The whole Darwinian principle of selection
and progress finds its application also in the
generalisation of the doctrine of repetitions.

THE DISTINCTIVE CHARACTERISTICS OF THE

MAMMALIA.

The earlier zoologists, with Linnaeus, classed
together as one species all those individuals * that
agree in essential points and have been descended
unchanged from the same ancestors.' The later
zoologists replace this supposed straight line of
descent, which involves the miracle of creation
and also the future invariability of organisms, by
including the agency of variability dependent upon
time and circumstances. As long as animal beings
of a supposed or proved common descent agree in
form and structure, we leave them together as one

DISTINCTIVE CHARACTERISTICS. 31

species : the idea is one of most uncertain limit,
and differs according to the views of each investi-
gator. We know of many species of such stability
that the earlier definition would seem to find its
application in their case ; but there are others
again whose variability, indefiniteness, and inde-
finability have baffled all attempts at a more
accurate limitation.

Species of this kind, consisting of a mere suc-
cession of forms, are now met with principally
among the lower orders of animals ; for instance,
the Sponges consist almost entirely of such a
succession of forms which seem to merge one into
the other. The Mammalia, on the other hand,
have in the course of the later geological periods
settled down more quietly. The days when they
were undoubtedly much more varied in form than
now, and — like the lower orders— developed almost
entirely into varieties, are passed. In the grand
sifting process of thousands of years, numerous
forms have dropped off and vanished, and the
majority of the mammals of the present day might
lead one to assume the stability of species.

The Mammals of to-day are sharply separated
from the other vertebrates by a series of pecu-
liarities in structure and development. Even the

32 THE MAMMALIA,

entirely changed mode of life of the Cetacea has
not ohscured, or only superficially obscured, these
characteristics ; for even the loss of the hind limbs
is of subordinate importance compared with other
significant peculiarities of the class, and moreover
the loss of limbs is met with in other classes, and
only shows to what extent the members of one
group may diverge.

We will mention one characteristic in the
skeleton which distinguishes the whole group of
existing mammals from all other vertebrates : their
lower jaw is directly attached to the skull, and
not by means of the so-called * quadrate bone.'
This bone is met with from the fish to the bird,
mostly as one of considerable size. Indications
of it occur also among mammals. The substance,
however, does not harden into bone and become'
the stalk of the lower jaw so easily recognised
in the heads of birds, but is employed in forming
one of the small bones of the ear. Further, in all
of the Mammalia the chest and abdomen are sepa-
rated by the diaphragm or midriff, a muscle which
is exceedingly important for the mechanism of
breathing. All the Mammalia have lacteal glands,
and in the case of most mammals the foetus is
attached to the mother by a placenta, so that the

DISTINCTIVE CHARACTERISTICS. 33

nutrition and growth of the embryo do not require
to be restricted to the comparatively small amount
of yolk in the egg, but, as a rule, are derived
directly from the blood of the mother.

We know of the * quadrate bone ' -which in the
Mammalia has to a certain extent become dis-
placed and slipped into the skull — from the Fishes ;
we see the beginnings of a diaphragm in the
Amphibians ; we find various kinds of skin-glands
(to which the lacteal glands belong) in all of the
Vertebrates ; there is but one step from the distri-
bution of the embryonal blood-vessels on the so-
called allantois of reptiles and birds, up to the
formation of the placenta : these characteristics of
the Mammalia are all prepared or begun in the
lower classes of animals. But the placenta came
into existence only with the actual mammals, and is
an acquisition towards a higher degree of progress.
But although these characteristics are obviously
inheritances — apart from the last-named arrange-
ment, which was acquired only subsequently — still
we are absolutely without any transition forms. It
can only be said that the Mammalia must have de-
veloped from one stock, where the characteristics
of the present Amphibians (for instance, the two
occipital condyles at the back of the head) were

34 THE MAMMALIA.

allied with those of the present reptiles (e.g. the
allantois). The earliest traces of mammals from
the Triassic rocks lead us to suppose a long series
of predecessors, and direct our thoughts to further
unfathomed depths of the earth's development.

It is a different matter as regards those charac-
teristics which the systematic zoologist makes use
of, first of all in distinguishing the subdivisions of
the group, the differences of the instruments of
locomotion, more especially of the outer limbs,
hands and feet, and also of the dentition. The
function of propagation exercises universally a
more subordinate influence upon the outward
appearance and the general habitus of the animal,
than does nutrition. The manner in which its
food is acquired gives the organism its peculiar
stamp, apart from the outer covering that acts as
a protection against its enemies and climatic
changes, and varies accordingly; and this stamp
is expressed chiefly in the formation of the limbs
and the dentition of the mammal. Cuvier's words,
* Give me a tooth, and from it I will build up the
whole animal,' are to be taken seriously ; they
may be applied to almost every other individual
part of the skeleton, and above all to the extremi-
ties of the limbs. The last portion of a finger will

DISTINCTIVE CHARACTERISTICS. 35

often suffice to determine the order. A whole toe
will give a complete idea of the mode of life and of
the appearance of the primeval or still living
animal. In order, therefore, to obtain an insight
into the relationship and social position of a
mammal form, we must first of all become ac-
quainted with the foot of the vertebrate in its
simplest accessible form, and then examine the
different variations of the mammal foot under the
supposition of direct transformation. This study
was undertaken for the first time with perspicuity
and success by Gegenbauer ; and thus later modifi
cations — which became specially necessary, owing
to the primeval form of fin of the Australian
Ceratodus — could perfectly well be explained in
connection with Gegenbauer's conclusions both by
himself and others.

The simplest form of hand and foot is met with
in the four-fingered and five-toed Amphibians and
various reptiles, e.g. the tortoises. Among the former
the rudiments of a sixth, sometimes even of a seventh,
toe are met with ; but with the exception of these
few indications, and the sixth finger of some
amphibian-like primeval animals, there are no
fossils relating to the early history of hand and
foot, or their transformation from the fish's fin.

36

THE MAMMALIA.

On the other hand, the five-toed limb extends from
the salamander to man. Together with this we

have the most
various kinds of
disappearances
and. coalescings
till we reach the
one-toed foot of
the horse, and
find, in fact,
that a diminu-
tion in the num-
ber of fingers
and toes takes
place ; never do
we meet with
a restoration
after the de-
crease, and
never with an
addition to the

FIG. 1.— Eight hand of a river tortoise, number of toes.

Nat. size. T ^

In order to

illustrate the fundamental form, which we shall
follow in its most varied and interesting changes,
let us take the right hand of a fresh-water tortoise

DISTINCTIVE CHARACTERISTICS. 37

(Chebjs fimbriata) in its connection with the lower
arm (fig. 1). The two hollow bones of the fore-
arm running parallel with each other are the
radius (s) on the thumh-side, and the ulna
(E). Then comes the root of the hand, consisting
of nine separate little bones, to know which in
detail is part and parcel of the A B C of the study
of the Mammalia. The first, r (radiale), lies close
to the radius, a second, u (ulnare), stands in the
same relation to the ulna. Between the two is a
connecting bit i (intermedium), and in the curve
formed by the three is the little central bone c
(centrale). The five other parts of the root of the
hand, 1, 2, 3, 4, 5 (carpalia), belong each to one of
the fingers, or rather to the five parts belonging to
the middle hand (metacarpus), i, n, in, iv, v, before
the actual fingers. The foot with the shank shows
precisely the same construction in number and
position of the parts.1 There would be no need
to give these names in the example chosen, had not
the inquiry and naming proceeded from the anatomy

Hand Foot

1 Radius, Spoke Tibia, Shinbone

Ulna, Ell Perone, Fibula
Carpus, Root of the hand Tarsus, Root of the foot

Metacarpus, Middle of Metatarsus, Middle of the

the hand Foot

Digits, Fingers Toes.

38 THE MAMMALIA.

of the human subject, where the contrast between
hand and foot has advanced in a very striking
manner. Our foot has remained an organ of sup-
port, our hand has become the organ for grasping.
The fibula, which corresponds to the ulna, is
reduced, the tibia is the principal bone. The parts
of the fore limb called the radiale and intermedium
(r, i) have generally coalesced into the spring-
lone (astragalus), and the bone of the root of the
foot attached to the fibula — the ulnare of the hand
— becomes the heel-lone (calcaneus), and is distin-
guished by a strongly-developed continuation at
the back ; the centrale exists as the skiff-lone
(naviculare). The first three bones of the middle
foot are called the wedge-shaped bones (1, 2, 3,
cuneiforme), the fourth and fifth bones of the
middle foot have united and form the cube-lone
(cuboideum).

In accordance with this scheme we shall find
that the different mammals show a similar contrast
in hand and foot — less in the fingers and toes
than in the roots of the hand and foot. It will be
our endeavour to bring this subject prominently
forward in the course of our discussion.

It will also be shown that the dentition stands
in as close a relation with the whole organisation

DISTINCTIVE CHARACTERISTICS 39

as regards form as well as the mode of life. The
study of the teeth has acquired an entirely new
interest since Gegenbauer has proved that the teeth
of sharks and rays are perfectly identical with the
scale and plate formations of their outer skin ; and
thus in the case of these fishes we can at once
see the transition of the outer body-skin into the
mucous membrane of the mouth-cavity, also the
direct transition of the hard formation of the skin
into movable teeth. Oscar Her twig has given us
a supplement to and a further application of these
fundamental inquiries. Accordingly, teeth have
originated from skin developments having been
used for the purpose of seizing and crushing food.
In the higher vertebrates we are no longer reminded
of this first origin of the teeth. "VVe there find
the adaptation to the new activity completed,
the organ has long since come to stand in a closer
relation to the skeleton as a whole. In the case of
every mammal the tooth, in its development, can be
traced to have proceeded from the membranous
covering of the mouth. And while the capacious
mouth and gullet of fishes has been able in almost
every case to cover itself with teeth, the Amphibians
and Eeptiles show a reduction in the number of
teeth and of the bony supports, and finally in the

40 THE MAMMALIA.

mammals we find only the actual jaw-bones fur-
nished with teeth.

By this a concentration of the tooth-material
has been accomplished, and connected with it we find
that concentration of force by which the mammal
more readily and surely overpowers its living prey,
and prepares it for use in the intestines, by mastica-
tion. In the dentition of the mammal we have not
a retrogression but an advance in the organisation,
and a further diminution in two directions may be
expected. What has taken place with numerous
fishes has also happened in the case of some
of the Mammalia : under certain conditions of
nutrition teeth have become useless and have dis-
appeared ; and, secondly, the fuller number of
teeth of the geologically older species has given
place to a dentition less numerous but more
specialised in form and action, and therefore more
advantageous. As an instance of the one direction,
we may take the jaw of a Euminant, which shows
a want of the upper incisors ; of the other direction
the jaw of the Cat species.

In order to understand the manifold forms of
teeth, we must have some knowledge of the develop-
ment of the various substances that form the tooth,
the origin of the hard bright enamel (ebur), of the

DISTINCTIVE CHARACTERISTICS. 41

tooth-bone (dentine), which constitutes the principal
portion of the tooth, and of the somewhat softer
cement (cementum), which serves in various ways
as material for covering and filling. A general
account will suffice for our purpose. The mem-
branous covering of the mouth-cavity — like that
of the outer skin — consists of two layers, the epi-
thelium (the upper skin), formed of several layers
of cells, and the membrane of the cutis (leather
skin), consisting partly of cells and partly of fibres.
The first sign of a tooth is a knotty protuberance
of the cells of the epithelium rising into the cutis.
Again, into this protuberance upwards there rises
from the cutis a cone-shaped elevation, upon which
there then appears the first formation in the shape
of a cap ; this is the enamel-germ or the enamel-
membrane which produces the enamel. The other
portion belonging to the cutis — i.e. the membranous
tissue of cells which rises up into the epithelium
and is termed the dentine-germ— becomes calcinated
into tooth-bone. But, in addition, the mem-
branous tissue of cells directly connected with the
dentine-germ produces — in various measures and
extent — the fewer-celled and softer cement round
about all the immediate surroundings of the tooth.1

1 Baume, Odontologische Forschungen, I. Th. ; published also

42 THE MAMMALIA.

The first indications of teeth are met with at
a very early stage of the embryo in the gums that
are still in the process of forming, and these be-
ginnings of teeth are then gradually enclosed by
the gums. In man and most of the other Mam-
malia during the first years of life we do not find
the whole set of teeth of their later years, of their
mature age, nor indeed any such teeth as are to
serve them throughout life ; there is at first a
temporary set of teeth, the so-called milk teeth.
These teeth are very like those that replace them
subsequently, the permanent teeth, but are smaller
and weaker. It was an extremely interesting and
important discovery when Eiitimeyer proved in
detail that the milk teeth of many of the Mammalia
show a greater agreement with their historical — i.e.
their geological ancestors — than do the permanent
teeth. As a rule, for instance, in man the first
set of incisors, canine teeth, and front cheek-
teeth are replaced by a second set, and thus con-
stitute the milk teeth. The teeth which replace the
milk cheek-teeth are called premolars, and these

under the title of Versuch einer Entwickelung&geschichte des
Gebisses (Leipzig, 1882). This work may be recommended as an
excellent one on the subject and full of suggestive thoughts,
even though we may, at times, feel disposed to dispute some of
the views put forward.

DISTINCTIVE CHARACTERISTICS. 43

are accompanied by the other back cheek-teeth, the
molars. But apart from the fact that in several
groups of mammals — the whales and armadilloes —
milk teeth do not occur at all (Owen's Monophy-
odonta), there are among those which do show a
change of teeth (Diphyodonta), so many deviations
and exceptions to the rule that, as Baume has
proved, the prevailing idea of change of teeth as
a succession of two distinctly different sets, can
scarcely hold good. The origin of the so-called
milk teeth can be traced back to the fact that with
the shortening of the facial portion of the skull,
the place for the incoming of the tooth-germ
naturally became smaller as well, and the germs,
in place of lying side by side, came to lie one above
the other. Hence those placed uppermost had to
be used first, before the lower ones had developed
and could uproot and finally expel their prede-
cessors by pressure. The weakening of an indi-
vidual milk tooth or of the whole set of milk teeth
will, accordingly, in general be a question of time,
and depend upon the delay in the development of
their successors. The milk teeth are at a disad-
vantage, owing to the inevitably hostile position
which their successors must sooner or later assume
towards them ; and they have to face a certain

44 THE MAMMALIA.

defeat, even though, in most cases, this takes place
with the utmost slowness. Instances of the loss of
milk teeth are met with among the Marsupials and
seals. The whole phenomenon belongs to the
chapter of ' abbreviated development.' It was our
intention here merely to point out this view of the
subject, in order to make use, in what follows,
of the designations given to different parts of the
jaw, according to position and time, since Cuvier's
and Owen's classical investigations.1

Let me here repeat that the specialisation of
the dentition frequently runs parallel with a speciali-
sation of the limbs. Thus, in comparison with its
geological ancestors, the dentition of the horse is
very specialised, and this is equally evident as
regards its foot, the transformation of which, from
a five-toed member — not specially suited either for
running, grasping, or climbing — into a one-hoofed
member, so admirably adapted for running, has

1 Example. — In man the milk teeth, the denies decidui, con-
sist of the cutting teeth (incisors), the canine or eye teeth, and
the two front cheek-teeth. In addition to these there are the
three back cheek-teeth that have no predecessors. The teeth of the
full-grown man are indicated thus : — i | c \p \ m f , i.e. on either
side above and below two incisors, one canine, two premolars
and three molars. Although Cuvier of course knew the dents
de lait and the dents de remplacement, still Owen was the first
rigorously to carry out the designation.

PALAEONTOLOGY SINCE CCVIER. 45

been accomplished step by step. Thus we very
often, and justly, hear of generalised and specialised
animal forms, which show their characteristic and
contrasting peculiarities chiefly in those organs, the
extremities and the dentition. These differences
were perceived even by the earlier observers, and
were compared with the embryonal conditions, with
the development from the general state of the early
indications through all the details of the ripening
offspring. The significance of this point must be
borne in mind when we term the geological and
earlier forms as general and embryonal forms, and
the later ones as the specialised forms.

THE EXTENSION OF PAL^ONTOLOGICAL SCIENCE

SINCE CUVIER.

The fact that the theory of descent appears less
prominent during the first half of our century, and
is so frequently and justly connected with Cuvier's
opposition to it, makes it necessary for us to allude
to his position in regard to this great question.
Cuvier's almost autodidactic manner of working
and viewing things comprised, as is well known,
the whole animal kingdom, with the exception of
some groups of microscopic and other lower ani-
mals. But he was a specialist, above all things, in

6

46 THE MAMMALIA.

the osteology of the living and fossil Mammalia,
and thus stands as the founder of palaeontology and
its comparative method. It was no small advan-
tage to Cuvier that in his immediate neighbourhood
were to be found deposits of the Paris Eocene, lime
and gypsum, containing the remains of the earliest
forms of mammals. It is astonishing what he accom-
plished in his ' Recherches sur les ossements fossiles,1
where his principle of correlation is so brilliantly
proved. The imperfectly observed geological facts
and the imperfect discoveries led him, nevertheless,
to the conviction that from time to time sudden con-
vulsions, catastrophes, had transformed the earth's
crust, and destroyed the living creatures, either
completely or with the exception of a small re-
mainder ; he further thought that those which sur-
vived were obliged often to seek a new home far
from their original abodes. The question as to
whence came the new inhabitants of the succeeding
peaceful period, after each of the great murderous
catastrophes, Cuvier settles in a somewhat cursory
manner. ' I do not maintain that a new creation
was required to produce the present species ; I say
only that they did not live in the same regions, and
that they must have come from elsewhere.'1 This

1 The quotation is from Cuvier's book referred to above— his
Ttcchcrches sur les ossements fossiles (1821).

PALAEONTOLOGY SINCE CUVIER. 47

vagueness remains in spite of his admitting the
fact that at one time life began on earth. For,
according to Cuvier, the varieties that are depen-
dent upon time, climate and domestication, remain
within a given boundary, while the species show
certain characteristics which resist every kind of
influence, and are as little affected by time as by
climate and domestication. Hence he directly
opposes Lamarck's theory of descent, i.e. that the
fossil forms are the ancestors of those of the present
day. His main argument is the want of fossil
intermediate forms, * for,' he adds, ' if the species
had changed gradually, we should find traces of
these gradual transformations ; we should find some
transition-forms between the PalaBotherium and the
species of the present day, and these have mean-
while not been met with.'

Cuvier therefore did not, as many have sup-
posed, hold fast to the belief in a supernatural cre-
ation from any preconceived opinion ; he was more
disposed to leave the problem as to the origin of
animal forms in uncertainty, as facts did not seem
to admit, meanwhile, of any safe conclusion. It is
therefore very intelligible that one of Cuvier's last
and still living pupils — the eminent palaeontologist
and zoologist, Eichard Owen — should straightway
have accepted the theory of natural descent (under

48 THE MAMMALIA.

a special Divine direction, it is true), after having
satisfied himself personally as to the existence of
intermediate forms between the Palseotherium and
Horse. Cuvier, his teacher, had, however, not
the desired knowledge of these forms.1

Since Cuvier's day, i.e. within the last fifty
years, and more especially within the last twenty
and twenty-five years, our palaeontological know-
ledge as a whole, and particularly as regards the
Mammalia, has been so immensely extended, that

1 Owen, in his Anatomy of Vertebrates, General Conclusions,
says : * With this additional knowledge, the question whether
actual races may not be modifications of those ancient races
which are exemplified by fossil remains, presents itself under
very different conditions from those under which it passed before
the minds of Cuvier and the Academicians of 1830. If the
alternative— species by miracle or by law — be applied to palaso-
therium, paloplotherium, hipparion, equus, I accept the latter
without misgiving, and recognise such law as continuously opera-
tive throughout tertiary time.' By law (natural law or secondary
cause), however, we understand nothing but a regular and re-
curring phenomenon where the acting cause is not touched upon.
This, according to Owen, is the Will of the Creator ; for he adds :
' I believe the horse to have been predestined and prepared for man.'
Hence natural law is in this case not opposed to miracle, but denotes
merely the manifestation of an Almighty Will working towards
a definite purpose. The same view is expressed also by Gaudry
in his Considerations sur les Mammi feres (Paris, 1877), where
he says: 'A mesure que j'ai cherche a comprendre 1'histoire
des gtres fossiles, il m'a paru de plus en plus probable que
1'Auteur du monde n'a pas cree isol£ment les especes succes-
sives des ages geologiques, mais qu'il les a tiroes les unes des
autres.'

PALEONTOLOGY SINCE CUVIER. 49

had Cuvier been able to make use of our present
material his conclusions would have been entirely
different. I have no doubt also, that our great
German teacher and master, Johannes Miiller,
would likewise have set aside his mystic ideas of
the origin of animals and of creation, in view of
the rising sun of Darwinism.

We have, of course, no intention here of giving
an account of the gradual extension of palaeonto-
logical science itself. Our object is rather to
explain how palaeontology and zoology inter-pene-
trate and correlate with each other. And it is
self-evident that in doing this the newer period
stands prominently forward, since the revival of
the theory of transformations. One of the condi-
tions of this theory of development is the overthrow
of Cuvier's theory of catastrophes, and indeed it
was finally overthrown for all time to come when
Lyell, in 1832, published his famous * Principles
of Geology.' Lyell there proved that the earth's
crust does not condense and change suddenly, and
that the geological periods of peaceful life have
not been separated from each other by general
convulsions extending .over whole continents, but
that the continuity of lands and seas has never
been entirely interrupted, even though they have

50 THE MAMMALIA.

often been disturbed by mighty upheavings and
sinkings.

The connection of the oceans must, in fact,
never be altered to account for the migration and
distribution of the animals. For instance, it is
now an established fact — from deep-sea investiga-
tions— that, since the chalk period at least the
bottom of the sea has experienced only unimportant
changes, changes that are almost imperceptible in
their slowness and their effect upon the animal
world ; its petrography has, in fact, undergone such
small changes that it may be said that we are still
in the chalk period, and that the formation of
chalk is still proceeding. And further, we may
assume the process to have been the same with all
the other and earlier geological periods. This
theory may, moreover, with certain limitations,
be applied to the main land. Larger accumula-
tions of land of some consistency are probably first
perceived in the Coal formation, and there can be
no question of continents, in our present sense of
the word, till the Jura and Chalk periods. At all
events, however, temporary connections of large
Jura islands — probably also the accumulations of
land belonging to the Trias — must have also existed.
For, not merely have we to date the individual

PALAEONTOLOGY SINCE CUVIER. 51

origin of the Mammalia as far back as the Trias at
least, and probably even further back, but we have
to assume that the class was one of pretty consider-
able extent. And, with the beginning of the
Tertiary period we already stand on the threshold
of the present. Whether or not there was ever a
Sahara ocean,1 or Europe ever half under water or
encrusted with ice, or England torn away from
the mainland by an inroad of the sea, or again
whether or not North Africa could exchange land
animals with South Europe by means of two
isthmuses — these and other incidents on a grand
scale would in no way affect the truth of an
uninterrupted development. There remain, it is
true, a series of ammo-geographical problems un-
solved, problems which are geological as well ; for
instance, the case of Madagascar, the distribution
of wingless birds, the Edentata, the isolated cases
of the Australian fauna, &c. These difficulties
must simply be accepted as such. They do not
hinder our recognising the natural connection of
the living world which is forced upon us by other
facts, and they do not oppose our present concep-
tion of the universe, which is already a very old

1 This conjecture may be said to be altogether refuted by the
latest investigations.

52 THE MAMMALIA.

one, although in its modern form it has the new
name of monism.

However, our intention was to speak of some of
the work that had been accomplished in our day in
the domain of palaeontology, which is intimately
connected with that of zoology. In the first place,
then, we must mention Kutimeyer's works, and
can, in fact, mention only some of his most eminent
and comprehensive publications. When Darwin's
grand work on the origin of species, the derivation
of domestic animals, and the influence of domes-
tication on the transformation of the original
species first appeared, and was being universally
talked about, as much interest was simultaneously
aroused by the discoveries of the Swiss lake-dwell-
ings. They gave the greatest impetus to the study
of modern anthropology, and also called forth
Butimeyer's work on the fauna of the lake-dwell-
ings,1 a masterly performance, and one precisely
such as was required by the new theory with its
very imperfect evidence. The manner in which he
explains the prehistoric discoveries by the races of the
present day in connection with the diluvial forms,
pointing out certain primary forms as the ancestors

1 Eiitimeyer, Die Fauna der Pfahlbauten in der Schweiz.
Basel, 1861.

PALAEONTOLOGY SINCE CUVIER. 53

of our domestic animals, more especially of the
oxen, the accurateness of his account of the actual
facts, the subtlety and carefulness of his combina-
tions— everything, in fact, makes Kiitimeyer's
work appear as if it had been ordered for a given
purpose. Soon after this, in 1863, he published
a work on fossil horses.1 This work, which was
undertaken by way of explaining the relation of
the genus Horse to its primeval ancestors, is, in
reality, a treatise on comparative odontography, or
the study of the teeth of the whole class of hoofed-
animals. The precision with which he points cut
the significance of the characters of the teeth, the
relation of the milk teeth to the permanent teeth,
the transitions in the geological successions of the
genera and species, and traces them back to uni-
versal principles and laws, can be compared only
to the sagacity of a Cuvier. I must confess
that I have never felt my interest so thoroughly
aroused in a subject, wholly distinct from my
own special study, as it has been by these two
works of the Basle zoologist.

Unfortunately, our greatest authority on do-
mesticated animals, Herman von Nathusius, wrho
died a few years since, and was always vehemently

1 Beitrage zur Kenntniss der fossilen Pferde

54 THE MAMMALIA.

opposed to the doctrine of descent, has left us a
fuller report only of the Pig family as regards what
he had to say in opposition to Eiitimeyer. He
never published a full account of his valuable com-
parative investigations respecting the domestic ox.
But Eiitimeyer has published a later and admirable
paper on this very subject, his object being to show
the connection between the living oxen and all
those belonging to the Diluvial and Tertiary periods.1
We shall presently have to quote from Eiitimeyer,
and may here supplement our remarks on his works
by mentioning his treatise on the genus Deer,2 which
is carried out in the same spirit. All of these con-
tributions are masterpieces as regards method, for
although starting from a limited horizon, they
extend over the whole earth, according to space
and time, and the claims of a practical speculation
are set forward in opposition to a system of phi-
losophy, according to which our investigations in
natural science would not have advanced beyond
the scheme of Plato's Ideas and Aristotle's Ente-
lechiae.

Eiitimeyer's investigations are not confined

1 Rutimeyer, ' Versuch einer natiirlichen Geschichte des
Rindes ' in the Beports of the Swiss Palceontological Society,
xxii. 1877.

2 Die natiirliche Geschichte der Hirsche I.e. 1880.

PALEONTOLOGY SINCE CUVIER. 55

merely to the objects found in the lake -dwellings,
the pea-ore and molasse strata of his native country,
for in his monographs, referred to above, he gene-
rally makes use of all the available material in the
European collections.1 We would mention together
with Eiitimeyer two French naturalists, Albert
Gaudry and Filhol, both of whom have, as it were,
been forced by their important discoveries to come
forward with imposing proofs for the theory of
descent. It is more than twenty years since the
publication of Gaudry 's work on the fossils of
Pikermi.2 Pikermi is the name of a hamlet on the
road between Athens and Marathon, near which,
in the deposits of a mountain stream which at one
time rushed along there, are found an incredible
accumulation of vertebrates, more especially of
mammals belonging to the upper Tertiary period.
In summing up the results of his investigations
Gaudry gives his readers a picture of a tertiary
landscape and its forms of life, which we cannot
resist quoting word for word, as an example of how
our imagination should, in all cases, weave single

1 We must also mention here his extremely instructive paper
on Die Herkunft unserer Thierwelt (1867), although for us nowa-
days it certainly presents considerable gaps.

2 Animaux fossiles et geologic de VAttique (1862).

£6 THE MAMMALIA.

dry observations into a picture full of colour and
life.

' The province of Attica has undergone great
changes since the far off times when these animals
existed, the remains of which are accumulated
round about Pikermi. At the present day it is
a strip of hilly country twenty miles (lieues) long
and ten broad. That this locality should have
been considered the abode of the gods, and should
have witnessed the glory of the most eminent
minds of antiquity, is quite intelligible. But the
numerous and gigantic four-footed creatures of
primeval times required a wider area, and they are,
moreover, too like the present species from the
interior of Africa for it to be possible that they
could have lived in Greece under the same con-
ditions as exist at present. Without doubt at one
time Europe was connected with Asia by un-
interrupted plains that are now covered by sea.
We must also imagine these plains to have been
provided with a more luxurious vegetation. The
marble hills of Pentelicus, Hymettus, and Lau-
rium produce now only small plants upon which
the bees find their food. At one time valleys with
a rich vegetation must have run along by the
side of those barren hills, and grassy meadows

PALEONTOLOGY SINCE CUVJEE. 57

alternated with splendid forests. For an abundance
of animal life demands a corresponding fulness of
vegetation.

' Those landscapes were enlivened by the most
varied forms of mammals, by the two-horned
rhinoceros and the gigantic boar ; also by monkeys
leaping from rock to rock ; carnivora — from the
families of the civet-cats, martens and cats — all on
the hunt for prey ; the caves of the Pentelicon hills
were inhabited by hyaenas. In the same way as
quaggas and zebras now inhabit Africa in enormous
numbers, immense herds of Hipparion must have
there careered across the plains. Not less fleet in
their movements, and of an even lighter build, were
the antelopes, also in great numbers. Every troup
of a distinct species would be distinguished by the
form of their horns : those of the Palreoreas had a
spiral twist like those of the eland of the Cape ; the
horns of the Antidorcas were curved in the form of
a lyre ; in the Palaeoryx they were long and bent.
The horns of the antelopes resembled those of the
gazelles, those of the Tragoceras were placed like
those of goats. Palaeotragus wras distinguished by
a slighter build and a narrower skull, with horns
situated immediately above the eyes. But Hella-

dotherium and another species somewhat akin to
7

58 THE MAMMALIA.

the giraffe towered above all of the Kuminants.
And Ancylotherium also — one of the Edentata —
was a creature of considerable size with bent toes.
The most gigantic of all the animals, however, was
the Dinotherium. What a magnificent sight it
must have been to see it marching about, accom-
panied by two species of mastodon ! In those
plains was heard the roaring of the frightful
Machairodus with its sabre-shaped canine teeth ;
and many other species associated with those
named above. Their cries were intermingled with
the songs of birds, and in the concert raised by
all these creatures the voice of man alone was
wanting.

1 Nowhere does the earth now present a similar
scene, as we may be convinced by a glance at our
present fauna. In the virgin primeval forests of
America, where plant life is met with in the full
majesty of development, we might expect to find an
equally full development of animal life. But the
four-footed animals are less powerfully developed
there than in the Old World, and are even less so in
Australia. In Europe and Central Asia they have
decreased in numbers by having been hemmed in
between the civilisation of the temperate zones and
the ice of the north. The largest mammals of the

PALAEONTOLOGY SINCE CUVIER. 59

present day are found in India and more particularly
in Africa. Delegorgue, in his account of his explora-
tions in Africa, describes a lake which was inhabited
by a hundred hippopotamuses, and within a space of
3,000 (?) he found more than six hundred elephants.
On one occasion he met with from three to four
hundred hygena-dogs, and again with troups of from
four to five hundred quaggas. Livingstone relates
that he frequently saw herds of more than four
thousand antelopes passing. One of his descriptions
of this wild part of the earth runs somewhat thus :
" hundreds of zebras and buffaloes were seen
crossing the plains ; numbers of elephants were
seen feeding, and their trunks alone showed any
signs of movement. I should have liked to have
photographed the picture, for scenes like this will
vanish when firearms are brought into use, and
will then be forgotten. It is perfectly marvellous
what immense numbers of animals are to be seen
crossing the country. I could fancy myself trans-
ported back to the days when the giant sloth
roamed about the primeval forests."

Gaudry goes on to say : ' However splendid
such pictures may be, old Greece could offer even
grander scenes. In fact, while the whole of Africa
is the home of but one species of elephant, Pikermi

GO TtiE MAMMALIA.

had two different forms of Mastodon and the
Dinotherium, the principal giants among the
four-footed animals. Africa has only one kind of
giraffe. Attica possessed a giraffe surpassing all
the living antelopes in size, and the Helladothe-
rium, an animal with short legs, it is true, but
larger than the giraffes in bulk. Among the living
Kuminants there are none that can be compared
with the Helladotherium ; the camel is much
inferior in size. Africa has but one species of
rhinoceros, distinguished by its rudimentary
incisors, whereas in Pikermi are found a rhino-
ceros of the African type, another of the Asiatic
species, and in the Acerotherium, probably also a
genus related to the rhinoceros. The huge thick-
skinned animal, the Chalicotherium, which is said
to have been discovered in Greece, is unequalled
by any in our day. The skull of the Eryman-
thian boar exceeds that of the wild boar by
one third ; and among the latter are some larger
than the wart-hog and the masked boar of South
Africa. The earth-hog (Orycteropus), the largest
of the Edentata in the Old World, is a miserable
creature compared with the Ancylotherium of
Attica. Lastly, the lion is surpassed by one of the
Carnivora of Attica, the panther by another.

PALEONTOLOGY SINCE CUV1ER. 61

' It is unjustifiable to dispute the existence in
the Greece of that period, of aquatic animals — such
as the river-horse, sea-cow, crocodile, which are of
frequent occurrence in Africa — simply because their
remains have not yet been discovered there. For
the stratum of Pikermi is essentially the result of a
mere landslip, inasmuch as the layer of mud which
surrounded the bones was washed down from the
heights, where there could be no waters inhabited
by those gigantic animals. As little does the
absence of anthropomorphous apes prove that they
never existed among the fauna of Southern Europe ;
the gorilla, for instance, inhabits silent forests
where scarcely any other four-footed animals are
met with.

* In Attica, therefore, more species of large
mammals are met with than in any other part of
the present world. I have no means of determin-
ing the number of the individuals of the different
species, but there is no reason to suppose that
this number was smaller than those of the present
species. Notwithstanding the great number of
animals observed in different parts of Africa, no-
where could a greater quantity of individuals be
found, on a space of the same size, as where I made
my excavations. This space — only a small portion

62 T1IE MAMMALIA.

of the entire stratum containing the bones— was
300 paces in length and sixty in breadth. The
quantity of bones all mixed up together, which a
fortunate excavation at times brought to light,
presented a remarkable sight. When I remind
my readers of the fact that I brought back with
me 1,900 pieces of Hipparion, more than 700
pieces of Khinoceros, 500 of Tragoceras, &c., it
will readily be understood that I was obliged to
leave behind me on my last journey the remains of
the commoner species of animals, to collect which
would only have delayed my examination of the
rarer pieces.'

Gaudry was able in every direction to deter-
mine the position of the different species which
had lived together on the ancient ground of
Pikermi, midway between the Miocene and Pliocene
deposits. One main result of his comparisons was
the proof that almost all belonged to that sort of
intermediate form of which Cuvier had so greatly
felt the want. * If,' says Gaudry, ' with all the
eminent palaeontologists of to-day, we add all the
other known fossils and living species to those
found at Pikermi, we feel convinced that the gaps
would disappear in the same proportion as new dis-
coveries are made.' Thus he found himself obliged

PALEONTOLOGY SINCE CUVIER. 63

to set up pedigrees — those systems of the probable
geological connection — which are ridiculed only by
persons who lack the preliminary knowledge for
forming a judgment.

Yet Gaudry, like other of his countrymen who
maintain the incontestability of the theory of
descent, is not a disciple of Darwinism— i.e. of
finding a proof for the theory of descent in the
hypothesis of natural selection in the struggle for
existence. He, like E. Owen, remains within the
realm of miracles, and supposes a personal Creator
to have directed the countless forms of develop-
ment towards definite and pre-ordained purposes.
With this conception of things — which at a certain
point sets sober inquiry aside — the assumption of
accident has to be met, and accident, in the
opinion of Darwin's opponents, is raised to the
rank of principle. We do not, of course, intend
here to enter into any further polemics while
speaking of the great achievements of a man who
admits his belief in such things, but still we must
again remark that even that which is called
accident is not beyond the pale of legitimate occur-
rence. We leave it to the reader to decide whether
it appears more reasonable to assume that the
absolute intelligence of a personal Creator should

64 THE MAMMALIA.

break off, for no result, millions of commenced
series, than that so-called accident should prevail
within the absolute laws of Nature.

Gaudry, in a very admirable work,1 has given
an account of the main substance and the results
of all the palseontologico-zoological inquiries.

Of even greater importance to the question
of transition- and intermediate forms are the
works of Filhol, a young compatriot of Gaudry's.
We refer to his papers on the 'Phosphorites of
Quercy,' 2 which appeared in 1876 and 1877 ; also
his article on the ' Fossil Mammals of St. Gerard le
Puy,' and his comprehensive treatise on the * Fossil
Mammals of Horizon,' which appeared in 1882.

Phosphorite belongs to the Upper Eocene for-
mation of South-western France, deposits of non-
crystallised phosphated lime. It is found in cracks
and hollows which have been filled up from above.
The deposit, Filhol says, was no doubt the result
of warm springs, which from time to time caused
extensive inundations, and drowned or suffocated

1 Gaudry, Les enchalnements du tnonde animal dans les
temps geologiques. Mammiferes tertiaires (1878).

2 Filhol, Bccherches sur les Plwsptorites du Quercy. Etudes
sur les fossiles qiCon a rencontres, et specialcment les mammiferes.
Annales des sciences geologiques, vii., viii. ; Mammiferes fossiles de
St.-Gerard le Piiy> Ibid. x. ; Mammiferes de Ronzon, xii.

PALEONTOLOGY SINCE CUVIER. 65

all living things. Pachyderms, Ruminants, Eo-
dents, Carnivora, all met with a rapid death to-
gether; frequently the animals were buried while
their skeletons were still intact. The deposits at
Quercy have furnished the most important facts
that have yet been discovered for the study of
the fossil Mammalia in Europe. They are as im-
portant as the more recent discoveries in America.
The characteristics of the animals met with in
France are perhaps less remarkable and conclusive ;
they are not striking at first sight, and it is only by
a very careful study of them that we perceive their
true value. The transitions are extremely delicate ;
we have there to do with shades of difference, not
with differences clearly expressed. Hence the
period of Phosphorite witnessed great changes, and
the types now existing were giving signs of appear-
ing. The influence of natural circumstances, which
we are not able to define more narrowly, but the
traces of which have been discovered, changed the
species in various ways and gave rise to varieties
which became fixed, and thus passed over into a
new species. Thus far Filhol.

Of the incredible wealth of forms among the
higher classes of animals in the South-western
Europe of those days, we have proofs in the fact

66 THE MAMMALIA.

that Filhol distinguishes, among the beasts of prey
alone, some forty-two species. In this abundance
of forms, in the occurrence of these most varied
kinds of flesh- and plant-eaters — which cannot be
imagined without a struggle for existence — we can,
as it were, quietly watch the gradual, very gradual,
process of transformation, the origin of species. The
inestimable value of Filhol's researches, like those
of Gaudry, is that they could extend over thousands
of objects. His investigations are peculiarly valu-
able, owing to the fact that three of the most im-
portant deposits of France and of Europe (Quercy,
Eonzon, and Gerard le Puy— the rich outcome of
which he was able to work upon), belong to three
closely connected geological horizons. And Filhol
has compared — in a way that scarcely any other
palaeontologist has done — the changes and advances
of the animal world from one of these periods to
the other, in their specialisations, and has placed
these in the foreground as the general result of his
most careful and detailed accounts.

Another investigator of great enterprise, Wol-
demar Kowalewsky,1 has unfortunately died at

1 W. Kowalewsky, Sur V Anchitlierium Aurelianense Cuv.
(Acad. de St. Petersbourg, 1873) : Osteology of the Hyopotamidts
(Philoso. Transact. 1873) ; Versucli einer natiirlichen Classifies,-

PALAEONTOLOGY SINCE CUVIEE. 67

too early an age. His works also belong to the
seventh decade and treat more especially of the
Hoofed animals ; they contain the most important
supplements to Eiitinieyer's works, for he, at
times, takes up entirely new standpoints for deter-
mining the connection between the present and
the remote periods. He has not done so much in
bringing to light new forms, as in carefully com-
paring those long since known. Certain opinions
about primary and fundamental forms, such as
Palaeotherium, Anoplotherium, Dichobune, and
others, which had become traditional since Cuvier's
day, he has finally corrected, and has in a masterly
way clearly defined the essential differences be-
tween odd-hoofed and pair -hoofed animals ; he has
also endeavoured to explain the disappearances of
forms, and the continuance and transformation of
others by very careful examinations, more particu-
larly of the hand and foot. Accordingly he has
set up pedigrees which do not indeed differ in
many points from the results given by Kutimeyer,
but they are certainly proofs of the extremely sug-
gestive and ingenious manner in which he con-
templates the primeval world, in its continuity with

tion derfossilen Huftliiere. Monographie der Gattung Anlhra-
cotherium (Palaeontographica, 1876).

68 THE MAMMALIA.

the earth as it is nowadays. Specially ingenious
I consider his distinction between the adaptive
and inadnptive reduction of the limbs, which we
shall have to consider more in detail when discuss-
ing this point.

Having now pointed out the direction in which
these investigators have worked, and their con-
ception of things in general as distinguished from
those of their numerous fellow-workers in the
domain of the higher animals, and having further
referred to the stimulus which their studies have
given to the theory of descent, I may now confine
myself to mentioning them only in so far as they
concern the palaeontology of the Old World.

Within the last fifteen years a series of sur-
prising discoveries have been made concerning the
palaeontology of America ; these discoveries have
almost subverted, at all events completely modified,
the opinions that had hitherto prevailed as to the
distribution and derivation of animals, in so far as
they concern the exchange and succession between
the Old and New World. We have a summary of
the zoo-geographical inquiries into those primary
periods in a work of Eiitimeyer's,1 not very com-
prehensive but rich in substance. He there says :

die Hcrkunft unserer Thierwelt, 1803.

PALAEONTOLOGY SINCE CUVIER. 69

' The whole surface of the earth of the Old World
during the Tertiary, as far as is known, formed one
single natural domain for the mammal fauna ; it
was more extensive, but the same as that which had
previously sustained the animal world of the Eocene
formation.' From here the primeval Mammalia
proceeded not only southward into Africa, but had
also, as it seems, found their way into the New World
by an isthmus of land connecting Europe with
North America ; partly also — as is shown by the
fossil elephants of Japan — from Northern Asia in
the direction of the Aleutian Islands. The fauna of
North America, the principal portion of which, to
all appearances, was not indigenous to the country,
then wandered southwards, following the course of
the principal mountain ranges, where they met
members of a foreign fauna coming northwards
from the south, and which in the more recent
periods even crossed the isthmus. At all events,
the Mammalian fauna of North America appeared
as inferior and dependent upon that of the East,
and immigration from the New to the Old World
seems a doubtful matter and even a question of
secondary importance. As Eutirneyer goes on to
say: * The Miocene fauna of Nebraska is the offspring

of the Eocene formation of the Old World. The
8

70 THE MAMMALIA.

Pliocene fauna of Niobrara, which lie buried in the
same ground as Nebraska, but in a later stratum
of sandstone, prove this in an even greater mea-
sure. Elephants, tapirs, and various species of
horses differ scarcely at all from those of the Old
World: the boars, to judge from their dentition,
are descendants of the Palaeochoerus, &c., of the
European miocene deposits.'

Even when these remarks of Eutimeyer were
written, we possessed an eminent work on the
Tertiary fauna of North America by Leidy.1 But
since those days the discoveries made have been
so extraordinarily numerous, and the immense
variety of animals that lived there has proved so
much more varied than the European fauna, that
American investigators, headed by Cope and
Marsh, have come to the conclusion that America
was not colonised with Mammalia from the Old
World, but that the former gave Europe some
of its original superfluity ; even the theory ac-
cepted by Kiitimeyer, that the Tertiary strata
of America were in part somewhat more recent
than ours, is proved to have been the reverse.
Marsh writes in 1877 : * These natural divisions
(of the American Tertiary) are not the exact

1 The Ancient Fauna of Nebraska, 1853.

PALAEONTOLOGY SINCE CUVIER. 71

equivalents of the Eocene, Miocene, and Pli-
ocene of Europe, although usually so considered
and known by the same names ; but, in general,
the fauna of each appears to be older than that of
its corresponding representative in the other hemi-
sphere—an important fact not hitherto recognised.'

The area of the life which extended throughout
the Tertiary period, and showed, in part, a closer
connection than can be proved in the case of
Europe, lies along both sides of the Eocky Moun-
tains. To the west — more especially in the region
of the Green Eiver — it extends up to the height
of the Great Salt Lake. It is more extensive
still to the east, where the so-called Bad Lands
(Mauvaises terres) in the state of Dakota are the
most productive centre.

Leidy's work on the ancient fauna of Nebraska,
which marks an epoch in the palaeontology of the
United States, has been completed by his investi-
gations on the extinct vertebrates of the Western
Territories.1 Since then not a year has passed
without Cope, and Marsh especially, bringing to
light new branches of this rich tree of knowledge.2

1 Leidy, ' Contributions to the Extinct Vertebrate Fauna of
the Western Territories,' United States Geographical Society.
Washington, 1873.

2 We do not yet possess any detailed account of this incom

72 THE MAMMALIA.

No less magnificent than these discoveries
relating to the Tertiary mammals, are the disclo-
sures concerning the Diluvial mammals that have
been made since Cuvier's day. But it is chiefly
South America that attracts our attention as
regards these. Most remarkable of all are the
discoveries of fauna from the Upper Tertiary and
Diluvial, which were found mainly in the caves
of the Brazilian province of Minas Geraes, and
also in the deposits of Argentinian! and Bolivia.
Fossil remains from the Eocene are very rare, and
of these remains those of the Palseotherium and
Anoplotherium from Europe, point to connections
of which geology has as yet heen unable to give
any explanation. Testimonies from the Miocene
are altogether wanting. On the other hand, the
later deposits show an extremely peculiar character,
owing to numerous, and in part colossal forms of
Edentata. Whether some of their most wonderful
representatives, such as the giant sloth, were

parably valuable material. We have to refer to the short papers
contributed to the American Naturalist, Stillman's Journal,
also to the Proceedings of the Amcr. Philos. Society. Marsh
gives a survey in the paper on the Introduction and Succession
of Vertebrate Life in America, 1877 ; also Cope's article, ' Mam-
malia Bunotheria,' in the Report upon United States Geogra-
phical Survey West of the One Hundredth Meridian , vol. iv.
Palaeontology, 1877.

PALAEONTOLOGY SINCE CUV1ER. 73

driven northwards when the isthmus was restored,
or whether, according to Marsh, the north was
the original home of this animal likewise, does
not seem to be a settled point. This Megathe-
rium was already known to Cuvier. But most of
the Edentata were not discovered till later, and
Lund's discoveries l in the cave-deposits of Brazil
may be said to mark an epoch; in more recent
times, Burmeister,2 a veteran in zoological research,
has in a masterly way described the gigantic
Argentine armadilloes and other animals.

A comparison of our present fauna, both of
Europe and Asia — as well as of the two Americas
— with that of the Diluvial period in these same
regions, will show the present at a very great
disadvantage; Wallace might well say that we
live in a world which is zoologically very im-
poverished, and from which the hugest, wildest,
and strangest forms have now disappeared. This
disappearance of numerous races of animals, in the
eastern and western hemispheres, almost makes
the impression as if it had been the result of some
such catastrophe as we have declared ourselves

1 Lund, Brasiliens Dyrverden. Copenhagen, 1841-45.

2 Burmeister, Annales del Museo ptiblico de Buenos Aires,
1864, p. 9.

74 THE MAMMALIA.

unable to admit. At all events, the period within
which the European mammoths and their asso-
ciates, the American mastodons, the giant sloths
and giant armadilloes, rapidly died out, must have
been very short in a geological sense of the word.
But there was no general destruction or dying out,
only a portion of the species became altogether
extinct, e.g. the horses of America: one portion
found means of differentiating, to adapt themselves
to a new locality, or returned at a later period to
their old home when the hindrances to their ex-
istence no longer prevailed. Among those inhabit-
ants of the earth able to cope with the existing
difficulties was Man, who may, with positive
certainty, be seen struggling through the whole
Diluvial period. All these signs of life succumbed,
or had partially to withdraw, before the great ice
formations which took place during the sub-
divisions of the Diluvial age. The cloak of ice —
evidently of many thousand years' duration — which
still persistently envelops Greenland, while Norway
and Sweden, in the same latitudes, enjoy the most
splendid green summers, gives us a vivid picture
as to how we have to conceive the enormous
glacial formations in Europe and America during
the Diluvial period.

PALAEONTOLOGY SINCE CUV1EE. 75

An extremely interesting question in palaeon-
tology, and one which is at present engaging the
attention of geologists, is, whether North Germany
was under water or encrusted with ice during
one division of the Diluvial. Nehring l has come
forward in support of the latter hypothesis. He
adduces weighty arguments against the drift theory,
i.e. against the generally accepted supposition that,
during one subdivision of the Diluvial, North Ger-
many was under water, and that the Scandinavian
blocks of granite scattered over the land were
deposited by icebergs from the north. His chief
argument against this theory is the utter want of
any remains of marine animals, the want of every
trace of shore fauna. Some few discoveries in
East and West Prussia, in Holstein and about
Hamburg, which have been examined by Berendt
and Jentzsch, ' prove only,' says Nehring, * that
certain limited portions of North Germany were,
during the ice period, covered by the sea perma-
nently, or perhaps only for a time.' For, he adds,
it was not sea but glaciers which covered the low-
lying plains of Germany, as far as the Hartz and
the other mountain ranges to the south. Where

1 Nehring, « Faunistische Beweise fur die ehemalige Verglet-
schemng von Norddeutschland,' Kosmos, vii. 1883.

76 THE MAMMALIA.

the glaciers themselves lay there are absolutely
no remains of animals, but remains are found in
those localities where the edges of the former
glaciers must have been situated. And all of these
remains belong to an Arctic Alpine fauna, such as
now live round about the North Pole — the reindeer,
musk ox, arctic hare, lemming, arctic fox, arctic
hen, arctic owl. The occurrence of all these animals
is carefully pointed out by Nehring, for instance,
at Tiede in Brunswick, and at Wester egeln. The
nature of the bones, and the discovery of young
specimens by the side of the older animals, shows
that the conclusion must be that the animals lived
there. It is still uncertain whether there was only
one, or two, or even several ice periods. The
Glacial period with its fauna was followed by one
with an improved climate, which, however, did not
as yet permit the growth of forests. A new fauna
appears corresponding with that of the steppes of
South-western Siberia — jerboa, suslik, lagomys,
saiga-antelopes. Gaudry, too, has shown that the
latter were also very widely distributed in France.
If Northern Europe had only one Glacial age, then
the period of the steppe fauna marks the retreat of
the glaciers in the very different configuration of
the land. If, however, there were two Glacial
periods — as seems very probable at least in the case

STEATA OF THE TERTIARY FORMATION. 77

of Switzerland — then those periods during which
the steppe fauna might have dispersed must have
been the intermediate epochs. However, we still
require much enlightenment on this point, and much
also remains to be explained as regards the causes
of all these ice formations.

It is not known how far back Man extends into
the Tertiary period. In the central and northern
latitudes of the Old World as well as of America
he could, of course, not gather into communities,
or rise above his origin, till the Glacial period (as
may be assumed) gave way to incalculably long ages
of assured order in the later geological period.
And Man's distribution over the earth is accom-
panied by a diminution of the animals.

THE STRATA OF THE TERTIARY FORMATION.

Air-breathing animals are met with first in the
Coal formation. Thereupon we have in succession
the Dyas formation (in Germany, Kupferschiefer
and Eothliegendes), the Trias (hunter Sandstein,
Muschelkalk, Keuper), the Jura with its numerous
divisions, and the Chalk. We possess a few fossil
remains of Mammalia even from the Trias and
Jura formations. Nothing is preserved in the
Chalk. On the other hand, the subdivisions of the
Tertiary are unusually rich in fossil remains of

78 THE MAMMALIA.

mammals. By way of pointing out the position
and succession of the formations, we will here add
a tabular view of the more important strata ; first
those of the Old World, where Central Europe is,
of course, the part that has been longest and best
known, and then a comparison of the divisions of
the Tertiary of North America. At the same time
the names of the more important species are given
by the side of the different strata in which they are
found. All that lies above the Tertiary formations
is considered as Diluvium, the lowest strata of
which are frequently also called Quartary or Quar-
ternary. It need scarcely be stated that there is
no sharp boundary between the uppermost Tertiary
strata and the lower Diluvial, and that the separa-
tion of the upper Diluvial from the later Alluvium
is equally indefinite. Owing to this difficulty
in distinguishing the different formations, most
palaeontologists prefer speaking merely of a lower or
an upper stratum of the Tertiary, in place of sub-
dividing it into Lower, Middle, and Upper Tertiary,
Miocene or Pliocene. The following arrangement is
partly taken from a tabular view given by Gaudry ; l
in the case of America we have followed Marsh.

1 Gaudry, Considerations sur Us Mammifdres qui out v6cu en
Europe a la fin de V&poqiie, miocdne. Paris, 1873.

STRATA OF THE TERTIARY FORMATION. 79

A. TEETIAEY FORMATIONS OF THE OLD

WORLD.

PLIOCENE.

19. Perrier. Crag of Nonvich. Val d'Arno. — Numerous deer.

Antelopes rare. Elephants. Mastodon.
18. Marl of Montpellier. Lignite of Casino. —Both deer and

antelopes. Hyaenarctos.

VIENNA BASIN II.

UPPER MIOCENE.

17. Pikermi. Baltavar. Mont-Leberon. — Helladotherium.

Ictitherium. Hyaena.
16. Siivalik Hills,
15. Eppclsheim. Oeningen. — Hipparion. Sus. Dorcatherium.

Tapir. Dinotherium. Simocyon.

MIDDLE MIOCENE.

14. Sansan. Georgsmiinde and Giinzberg. Eibiswald. — Ante-
lopes. Mastodon.

VIENNA BASIN I.

13. Limestone of Montabnzard. Sand of Orleans. Lignite of
Monte-Bamboli. — Palaeochoerus. Cainotherium. Dremo-
therium. Dicroceras. Dinotherium. Mastodon.

LOWER MIOCENE.

12. St. Gerard le Puy (on the Allier). — Anchitherium. Dremo-

therium.

11. Sand of Fontainebleau. Lignite of Cadicona. — Bhinoceros.
10. Lime rocks of Eonzon. — Gelocus.

UPPER EOCENE.

9. Phosphorite of Quercy.

8. Lignite of Debruge.

7. Paris Gypsum. Hampshire.

6. Sands of Beaiicliamp.

80 THE MAMMALIA.

6. Paris Coarse Limestone. — Characteristic are entelodon, hyas-
noclon, pterodon, dichobune, palaaotherium, anoplotherium,
xiphodon. In the upper strata are found also among
others anthracotherium, cainotherium.

MIDDLE EOCENE.
4. Mauremont. Pea-ore. Egerkingcn.

LOWER EOCENE.

3. London clay. — Hyracotherium. Pliolophus.

2. Lignite of Soissonnais. — Coryphodon. Palasonictis.

1. Sandstone of La Fere.— Arctocyon.

STRATA OF THE TERTIARY FORMATION. 81

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n,

SPECIAL COMPARISON OF THE LIVING
MAMMALIA AND THEIR ANCESTORS.

IN entering now upon an examination of the
different groups of the living Mammalia according
to their historical or palseontological past — an ex-
planation of that which has come to be out of that
which has been — the method to be followed is self-
evident : a systematic arrangement, proceeding
from the lowest to the highest forms, comprising
the result of anatomical as well as of palseonto-
logical considerations. The lower groups of Mam-
mals are, of course, those which have retained the
inherited qualities of their ancestors most distinctly,
and have changed least. This does not necessarily
include the certainty that they inhabited the earth
at an earlier period than all those whose skeleton,
brain, and foetal development show a pre-existence
of the lower forms, but end with a higher result.
The lower Mammals may have remained as a rem-
nant of a group whose nearest relatives — at first,

LIVING MAMMALIA AND THEIR ANCESTORS. 83

by scarcely noticeable deviations - -- raised them-
selves above their cousins by making use of the
advantageous changes and adaptations in their
organisations. And yet the probability is that the
lowest animal forms were, in general, also the
oldest geologically.

Although even Cuvier had prepared the down-
fall of Buffon's indefinite idea of arranging the
animal kingdom into one series, still it was not till
our own day that it became generally admitted that
the conception of a figurative expression for the
system could only take the form of an immense
tree, with hundreds of branches and thousands of
twigs. The animals we see living to-day are the
tips of the twigs and shoots ; those that preceded
them must be looked for down towards the branches,
and from these again down towards the trunk. The
comparison of a tree, howrever, serves only as a
means of arrangement. On our grand tree of life,
the branchings are all unlike one another, and
show resemblances only where they are in close
proximity ; the farther they have branched off from
the tree the more different do they become.

From another point also the figure of a tree
will give us a distinct idea of the actual state of
things. The farther we go back into the history

84 THE MAMMALIA.

of the existing animal forms the nearer we come
to their origin. In cases where to-day no connec-
tions seem to exist except the characteristics of the
class and order, in going back we find more definite
and ever clearer resemblances, till finally the com-
mon original forms are discovered. These have
often been called ' mixed forms,' which term, how-
ever, does not properly indicate the nature of the
matter. For in most cases the question is much less
about a combination of marked characteristics which,
in earlier times were, and at present are distributed
over different branches, than about a still undifferen-
tiated basis that has in various directions proved
itself transformable. For instance, the Hoofed
Animals, which when first met with are unfortu-
nately already very marked in character, possess
the full number of toes and a good supply of teeth.
Of the teeth it might indeed be said that they show
a ' mixed character,' inasmuch as the front ones
are more adapted for attack and defence, while the
rest are specially adapted for munching vegetable
substances. But if the earliest forms of Hoofed
Animals and the earliest forms of Carnivora point
to animals resembling the Insectivora in structure
and form, as their common ancestors, and these
again point to the Marsupials, we can assuredly

LIVING MAMMALIA AND THEIR ANCESTORS. 85

not call these mixed forms, but forms bearing the
impress of different circumstances.

But when brought into this connection with
the primeval world, the systematic arrangement of
the Mammalia — made in accordance with their
present state— must above all things appear alto-
gether unsatisfactory. The Mammals, as the most
highly developed animals, not only, of course,
stand farthest from the beginnings of animal life,
but they have also — at all events the Vertebrates
— diverged more from one another than any
other class. For even the Eeptiles, whose day is,
in every respect, long since past, are behind them
in this. However adaptable their limbs were to
circumstances (their teeth were less so), their brain
remained stationary. It was only with the charac-
teristic advance in the organisation of the Mam-
malia that scope was given to a progressive brain.
The attempts which have repeatedly been made to
make use of this point also for a systematic arrange-
ment of the Mammalia, have either been too one-
sided, or could not show any satisfactory result,
owing to the large gaps in our palaeontological
knowledge. It is reserved for the future to make
the systematic classification of the Mammalia a
really ' natural ' one, and one which shall attain the

86 THE MAMMALIA.

goal towards which Cuvier and Lamarck paved the
way with their grand beginnings, although starting
from such different points of view. Meanwhile
we must content ourselves with following the old
tracks.

1. THE MONOTREMA, CLOACAL OR FORKED ANIMALS.

An example as to how the animal form should
not he conceived is given by Giebel, a man of vast
knowledge but yet opposed to the theory of descent.
He says of the two well-known species of this group,
the Ant-eaters (Echidna), and the Duck-moles (Orni-
thorkyncha) : ' If there is anything marvellous about
any series of animal forms, the Cloacal animals ap-
pear the strangest of all ; for the irregularities and
wondrous shapes in the variously formed organisa-
tions of the Edentata are far surpassed by those
met with in the Cloacal animals.' Brehm also
does not carry us much farther ; he says : ' The
Ant-eater and the Duck-mole are still classed
sometimes with the Marsupials and sometimes
with the Edentata. And, in fact, they combine
not only the peculiarities of the one and of the
other class, but also the most varied and opposite
characteristics of the whole first-named class (the
Mammals) ; indeed, they seem, to a certain extent,

THE MONOTKEMA, OR CLOACAL ANIMALS. 87

to be the connecting links between the Mammals,
Birds, and Reptiles.' That he should regard
them as connecting links is certainly somewhat to
the point, only the Birds must be left out of the
question. A direct connection between Bird and
Mammal there is not ; they are allied through
their ancestors, and the latter stand widely sepa-
rated, although within the extremely comprehensive
order of Amphibio-reptiles.

Their beak-shaped jaws do not possess any
teeth ; only in the case of the Duck- mole do wre find
a few horny plates. This want of teeth has per-
haps been inherited from reptile-like ancestors, and
must have been distinct from the ancestors of the
toothed mammals ; hence it wrould be a case of
convergence. The possible case of the common
origin of Duck-moles and of Toothed mammals from
primary forms of toothless animals, and of the
acquisition of teeth by Mammals independent of
toothed ancestors, is in the highest degree im-
probable ; or else the loss of the teeth may have
occurred only at a later period, after a common
origin on the line of duck-moles, as in the case of
Birds and various Edentates, partially also in the
upper jaw of the Hoofed Animals, and in all cases
of the reduction in the number of teeth. We take

88 THE MAMMALIA.

all these possibilities into consideration without
gaming anything for the point in question.

It is, however, a different matter with the
following characteristics. The Cloacal animals are
the only Mammals where the collar-bones have
become united into one piece by means of the
breast-bone, as in the case of the well-known fork-
bone in birds. In all other Mammals, including
Man, we find, in place of this free os coracoideum,
a short hook, the crow-beak bone. This circum-
stance, in and of itself, might lead to the supposition
that the Duck-moles were more fully developed than
the other Mammals. However, from the course of
the development as a whole, it is obvious that
this portion of the shoulder of the higher Mam-
mals must be regarded as a case of reversion.
Another peculiarity of the skeleton of the Mono-
trema is a couple of bones which, turned towards
the front, rise above the pubic bones at the
abdomen side of the pelvis. These bones exist also
in the Marsupials. As, however, we are uncertain
about their origin and significance even in the case
of the Marsupials, nothing much can be made out
of the agreement. Still, the occurrence of these
bones in the two classes points to a close relation-
ship.

THE MONOTREMA, OR CLOACAL ANIMALS. 89

All the more characteristic is another peculiarity
of the Monotrema : the urinary and genital appa-
ratus have no separate openings, but one opening
in common with the intestinal canal, called the
cloaca. This stage of development at which the
Monotrema, like the lower Vertebrates,1 remain all
their life, is an embryonal stage in the case of all
the other Mammals, and not, as Giebel says, an
irregularity or singularity, but a perfectly normal
inheritance. In the other Mammals the peculiarity
exists normally as a transition form, but after
the embryonal life it is a condition that has been
overcome.

That the Monotrema possess actual lacteal
glands is a long-established fact. There are a
number of separate glands from which the milk
issues, not, however, from a teat or nipple, but
from flat, perforated patches of skin. These were
formerly held to be mucus- or perspiration glands,
but are now recognised as an actual proof for the
irrefutable supposition that the secretion of milk
was acquired only gradually. Those of our readers
who may consider this idea — of the common skin-
glands of the reptile-like animals having in the
course of time developed into the important

1 In most Fishes these arrangements are different.

90 THE MAMMALIA.

mammary glands — as very strange and but little
pleasant one, we would remind of the case of the
pigeons. Pigeons do not indeed possess glands
on the outer skin, but have glands developed in
their crops which provide the young with food ;
whereas in the other birds we find at most only
secretions for softening the food and preparing it
for digestion.

Owing to the fundamental importance of the
mammary glands, we must enter somewhat more
fully upon the subject here, while discussing the
lowest known forms of Mammals. The simplest
arrangement is that of the Duck-mole, such as was
perhaps inherited from unknown ancestors, but
which probably also represent a stage of reversion.
It is different with the Echidnas, porcupine ant-
eaters. We here find the perforated glandular
patch lying somewhat deeper and surrounded by a
circular wall of skin. In this so-called mammary
pouch the imniaturely-born offspring finds admis-
sion and protection, and by sucking forms for itself
probably a temporary pointed teat. The most
important matter is that the formation of the teat
or nipple begins in all the other Mammals and in
Man with the indications of this kind of mammary
pouch. The form and more delicate structure of

THE MONOTREMA, OB CLOACAL ANIMALS. 91

the outer milk apparatus does not appear to have
been directly transmitted only to the Marsupials ;
thus the various formations of teats, which can be
traced, from those first beginnings, amid all sorts
of modifications, through the whole series of the
higher Mammals, also corroborate the inductive
proof of the relationship of the whole mammal
world including Man.1 And even in this case the
history of the development of the living repre-
sentative of an animal group, supplements the want
of observations on conditions and processes that
have played a part in the remote period of the
earth's history.

A separate origin for the Monotrerna cannot be
unconditionally rejected, but is exceedingly im-
probable, if only on account of the perfect agree-
ment of the embryonal mammary apparatus of the
Marsupials and of the other orders, with the mar-
supial pouch of the Echidnas. The suppositions
favouring the possible independence of the Mono-
trerna do not, of course, possess any actual
foundation as long as we do not know the
amphibio-reptile forms where the mammal charac-
ter shows the first signs of incoming and of

1 Klaatsch, ' Zur Morphologie der Saugethierzitzen ' (Mor-
pholog. Jahrbuch, ix. 1883).

92 THE MAMMALIA.

becoming established. On the other hand, to
take a very obvious case, when competent au-
thorities emphasize the possibility that birds of
the ostrich species (the Ratitae) are of a different
reptile origin to the other birds — e.g. those with
a keel-shaped breast-bone— the supposition of a
convergence would, in fact, be established ; for bird-
like peculiarities are met with in the skeleton of
several fossil groups of reptiles, hence the trans-
formation to the real bird would in various respects
be absolutely no wonder at all.

The geographical distribution of the Monotrema
is confined to South Australia and Tasmania. But
a few years ago a new species of Ornithoryncha
was described from a perfect skull found in New
Guinea. This does not really make the range of
their distribution any larger, as New Guinea was
clearly at one time connected with the continent of
Australia, and consequently belonged to the same
zoological province. Not a trace of any fossil
discovery leads us from the present living Mono-
trema back to the primeval world, to which never-
theless they stand in such palpable relation. They
are, moreover, widely different from the other
groups of living Mammals. Even admitting the
debatable supposition that they were directly allied

THE MARSUPIALS, OR POUCHED ANIMALS. 93

to the Marsupials — hence derived from common
primary forms — their separation from these must
have taken place before the Trias period.1

2. THE MARSUPIALS, OR POUCHED ANIMALS.

The Marsupials stand in a remarkable position
between the Prototheria (the Monotrerna) and the
Eutheria (the ' higher Mammals '), but obviously
their relation to the latter is more direct, whereas
the gap between the Monotrerna and the Mar-
supials is left to the free play of the imagination.
It is not readily intelligible how the marsupial
pouch of the Echidna — which serves to protect
the helpless offspring — could have originated by
natural selection. Here the two bones rising from
the pelvis, the ossa epipubica, transmitted to them
by their ancestors of the monotreme species, have
been brought into connection. The openings of
the urinary and genital organs have remained
at a low stage and show resemblance to the

1 For the sake of clearness and simplicity we intend in the
following pages, with Huxley, to call the Monotrema, as the lowest
Mammal form, Prototheria. They are followed by the Marsupials
as Metatheria ; and all the other orders comprised as the 'higher
Mammalia ' then follow as Eutheria. Zoologists will know that
the two last designations stand for the more general terms
Didelphia and Monodelphia, which, however, require a special
explanation.

10

94 THE MAMMALIA.

arrangement in the Monotrema. The young leave
the maternal womb in a very immature state, i.e.
the nourishment, the renewal of blood in the
uterus which, in the case of the Eutheria (the
high Mammals) is regulated by means of the
placenta for the advantage of the offspring, must,
owing to the absence of this foetal organ, be
accomplished at an early stage by mammary
glands. The further development of teats, in ac-
cordance with a beginning corresponding to the
marsupial pouch of the Echidna, has already been
mentioned.

A fresh feature by which the Marsupials are
brought into direct connection with the higher
Mammals is their dentition. And, moreover, with
their dentition they extend back beyond the Mono-
trema to primary amphibian forms, and at the
same time the great variety of the forms prove,
in a most obvious way, that they have differen-
tiated from the simpler beginnings of their ancestors,
in so far as they were obliged to do so owing to
the generally more uniform surface of the earth.
One peculiarity affecting the whole group of Mar-
supials is this, that only one pair of teeth in either
jaw is changed during the lifetime. The succes-
sion of the teeth with the incoming of the one

THE MARSUPIALS, OR POUCHED ANIMALS. 95

deciduous tooth, is not a safe starting point for
making a satisfactory comparison of their denti-
tion with that of the Eutheria (the higher Mam-
mals).

In an interesting paper on the classification of
the Mammalia, Huxley l says : ' As Professor
Flowers has pointed out, the question arises
whether we have here a primary dentition with
only one secondary tooth, or a secondary dentition
with only one tooth of the primary set left. I
have no douht that the answer given to this ques-
tion hy Prof. Flowers is correct, and that it is
the milk dentition of which only a vestige is left
in Marsupialia. Among existing Eodents, in fact,
all conditions of the milk dentition exist from a
number equal to that of the permanent incisors and
premolars (as in the rabhit) to none at all. The
same thing is observed in the Insectivora, where
the Hedgehog, and probably Centetes, have a full
set of milk teeth while none have yet been found
in the Shrews. In these cases it is obvious that the
milk dentition has gradually been suppressed in
the more modified forms ; and I think that there

1 ' On the Application of the Laws of Evolution to the Arrange-
ment of the Vertebrata, and more particularly of the Mammalia '
(Kosmos, ix. 1881).

96 THE MAMMALIA.

can be no reasonable doubt that the existing Mar-
supials have undergone a like suppression of the
deciduous teeth in the course of their development
from ancestors which possessed a full set.' If this
is the right explanation, the suppression of the
milk teeth in Marsupials must be transferred to
a comparatively more recent period when the
branching off of the Eutheria, which still possess
the milk teeth, had not yet taken place. A proof
of this is that some groups of Mammals do not
show this succession of milk teeth and permanent
teeth, or rather that they have lost it notwith-
standing a relationship marked by a change of
teeth.

As regards teeth and limbs, the Marsupials
of to-day bear testimony to no small amount of
adaptability. It may be compared with that
adaptability which is evident in the whole class of
the higher Mammals, if we are not to admit that
the Eutheria have originated separately in groups
from the already modified Metatheria. True, the
most useful and docile Hoofed Animals are looked
for in vain among the Marsupials, and notwith-
standing the great diversity in the formation of
their teeth — which goes hand in hand with their
mode of life— the types of the insect-, flesh-, grass-

THE MARSUPIALS, OK POUCHED ANIMALS. 97

and root-eating Marsupials are far more alike in
structure than are the Eutheria among one another.
The largest numbers of teeth — fifty — is found in
the opossum, Didelphys. The marsupial pouch —
the characteristic feature of the class — has, it is
true, become reduced to a few unimportant folds on
the abdominal skin. Still, because of the number
of their teeth, and because the earlier fossil Mam-
malia show most affinity to them, they must be
regarded as the least modified members of the
family.

The Didelphida?, or Marsupial Eats, are now
confined to southern and central America. Neither
geology nor palaeontology gives us any clue as to
how this has happened: whether and when this
branch separated from the main group confined to
Australia : whether the agreement of the Didelphidas
with the other Marsupials is a matter of converg-
ence : or whether the Australian Marsupials are of
American origin. However, we shall have to return
to this latter supposition owing to an anatomical
peculiarity. The dentition of the Marsupial Eat
shows most resemblance to our Insectivora, and they
also agree with them in many ways as regards mode
of life and food. Even Cuvier discovered their fossil
remains in the Eocene strata of Paris. It was only

98 THE MAMMALIA.

at a much later date that K. Owen l traced similar
animals back to the Trias formation.

In the so-called Ehaetic beds, one of the sections
of the Trias, a few minute teeth were found which
probably belonged to an Insectivorous Marsupial ;
these teeth have given rise to the genus Microlestes.
Again, in the Lower Lias (of the Jura formation),
fragments of lower jaws have been found that must
be regarded as belonging to small Insectivorous
Marsupials. Phascolotherium is most frequently
mentioned. Similar remains are found in the strata
directly below the Chalk formations, and among
these we have Plagiaulax, very remarkable on
account of the reduction and specialisation of its
dentition. In Fig. 2 we have the lower jaw of PL
minor (A) in natural size. Hence it was an animal
of the size of a mouse. In the enlarged jaw of
another species (Fig. 2, B) the premolar (?), marked
by number 4, and followed by two molar- shaped
teeth, shows the very marked character of the
genus, which is less distinct on the preceding
teeth — i.e. the deep diagonal grooves.

Owen looks upon all these imperfect remains as
' generalised forms,' whereas Huxley asks, what are

1 Owen, ' Monography of the Fossil Mammalia of the Mesozoio
Formation ' (Pal&ontological Society^ 1871).

THE MARSUPIALS, OR POUCHED ANIMALS. 99

the peculiarities of the more embryonal or less
specialised type of the Phascolotherium as compared
with the Opossum of to-day. Upon the whole Owen
seems to us to be right, as regards the dentition,
in coming to the conclusion that from Phasco-
lotherium to Didelphys we have an advance from
the generalised to the specialised form. This sup-
position cannot, however, be extended to Plagiaulax.

FIG. 2.

A. Lower Jaw of Plagiaulax minor. Natural size.

B. Lower Jaw of PI. medius. Tour times enlarged.

This animal appears rather to be already so far
specialised that it advanced but little farther in
subsequent times ; nay, if the line were carried
down to the actual present, it might even be said
to have become effaced.

The remains found of Plagiaulax show the
following connection with the living Marsupials.

100 THE MAMMALIA.

An animal allied to the European Plagiaulax is
described by Marsh from the Jura of Wyoming —
Ctenacodon - - without the above-mentioned deep
grooves on the premolars, but they are jagged on
the upper edge.1 In addition to this, in 1883
a discovery of great interest was made, by which
the connection between the primary and the exist-
ing Marsupials has been almost directly restored.
In the Lower Eocene, in the neighbourhood of
Eheims, Lemoine found the jaw of an animal which
shows a remarkably grooved tooth as the only pre-
molar, and behind it two low tuberculate molars
(Fig. 3, A). Owing to its close resemblance Lemoine
called it Neoplagiaidax, and classes it by the side of
the existing dwarf-kangaroo of Australia, the Bet-
tongia penicillata (Fig. 3, B). This latter also has
a grooved tooth, even though somewhat less deeply
marked.

As the Eocene animal has two, and Bettongia
three teeth behind the grooved tooth, we cannot, of
course, speak of any direct relationship, but we
may assume a lateral connection between the two.

1 We shall here use the words premolars and molars (as most
palaeontologists do), although according to the conditions of the
living Marsupials, we are not absolutely certain whether we are
right in distinguishing the teeth of the fossil forms as milk and
permanent teeth, premolars and molars.

THE MARSUPIALS, OR POUCHED ANIMALS. 101

Lemoine also finds agreements between Plagiaulax
and Microlestes, and has thus lengthened the series
from the Present to the Trias formation. The
French zoologist further discovers in the upper
cheek-teeth of the Brown Eat similarities with
teeth which, found isolated, probably belong to

FIG. 3.

A. Lower Jaw of Neoplagiaulax.

B. Lower Jaw of Bettongia penicillata. After Lemoine.

Plagiaulax. All this points to the primeval stock
where Marsupials, Insectivora, and Eodents meet.
But we cannot imagine that Plagiaulax was an
insect-eater ; I should be inclined rather to assume
that Bettongia lived upon vegetable food.

The scientific dispute regarding the mode of

102 THE MAMMALIA.

life of Plagiaulax — as expressed by its dentition —
which has been carried on with much animation,
more particularly by English enquirers, also affects
a Marsupial of the Diluvium ; and Owen has ex-
pressed his conviction as to the carnivorous habits
of the animal (which is almost the size of a lion)
by the name he gives to it, i.e. Thylacolco carnifex.
Its skull, like that of many of the Marsupials,
shows the peculiarity of strongly developed middle
incisors. The canines and front cheek-teeth are very
insignificant. But both above and below follows
a huge, compressed premolar which involuntarily
reminds us of the canine of the large cats of our
day. The rest of the back teeth, also, do not op-
pose the supposition of its being carnivorous, hence
here again we do not understand Owen's learned
opponent who would characterise Thylacoleo as a
plant-eater. We agree with Owen's opinion that
none of the existing Carnivorous Marsupials show
a similar concentration of the dentition — such a
good or serviceable set of teeth— as Thylacoleo^ in
whose case this direction of development has ex-
hausted itself. But does our Marsupial Lion show
affinity with Plagiaulax^ as Cope would have us
believe ? Quite apart from the question of food,
we consider a transition from the dentition of

THE MARSUPIALS, OR POUCHED ANIMALS. 103

Plagiaulax to that of Thylacoleo as exceedingly
improbable ; besides this, the discovery of the
Neoplagiaulax leads us to an entirely different
track from Plagiaulax.

The Marsupial Lion of the Australian Pleisto-
cene takes us back to the time when the group had

Fio. 4. — Skull of Diprodon Australia. One-tenth natural size.

After Owen.

reached its fullest development (followed by a some-
what rapid decline), and which presupposes a similar
and contemporaneous abundance of plant-eaters
necessary for the sustenance of the huge flesh-
eaters. And there exists at least one species of
those theoretically required— the colossal Dipro-

104 THE MAMMALIA.

todon australis, whose skull is one metre in
length. It was obviously a plant-eater with a
specialised dentition, as is proved by the peculiar
incisors and the compressed cheek-teeth, which are
separated from the incisors by a considerable gap.
According to Owen's masterly comparisons, in
Cuvier's style, Diprotodon was a gigantic kangaroo,
but without the power of leaping. Like most of
the primeval species which attained an unusual
development of strength and a certain monstrosity
of form, it has not left any direct descendants, but
together with it there lived, in those days, powerful
creatures closely related to the kangaroos, such as
Palorchestes, with a skull 40 cm. in length.

Wombats also (Phascolomys), of which there
exist only a few species, find then- fossil com-
pletion in numerous species of this genus, and
partly corresponded with them as regards size, and
partly far surpassed them. They appear all to
have been root-eaters, and, as is well known, the
habitus of the Eodents is repeated in a remarkable
manner within the group of Marsupials. The one
that can most readily be compared with them is
the Nototheriumy which again is a creature that far
exceeds the living species in size, with a skull of
the most ugly description imaginable. While the

THE MAESUPIALS, OR POUCHED ANIMALS. 105

FIG. 5. — Skull of the Wombat (Phascolarctus fuscus). One-half

natural size. After Owen.

FIG. 6. — Skull of Nototherium, from the side. Oue-sixth natural

size. After Owen.

11

106

THE MAMMALIA.

Phascolarctus fuscus of the present day (Fig. 5)
shows a skull of 19 cm., the skull of Notothe-
rium Mitchelli (Figs. 6 and 7) is 46 J cm. long, to
40£ cm. broad. The breadth is caused by the
enormous arch of the cheek-bone. The cheek-teeth

FIG. 7.— Skull of Nototherium, front view. One-sixth natural

size. After Owen.

are very like those of Diprotodon, and are likewise
furnished with transverse ridges, the whole dental

O f\ K

formula being the same : i c m ~. The struc-

105

ture and form of the teeth point to a plant-eater,
and not to the habits of a wombat that grubs for
roots.

THE MARSUPIALS, OH POUCHED ANIMALS. 107

All of the above-mentioned fossil Marsupials,
which have been described by Owen in his
masterly work,1 belong to the most recent geological
past. They are found principally in Eastern and
South-eastern Australia, partly in river-beds —
as for instance in that of the Condamine and
its tributaries — and in the dried-up deposits of
fresh waters, partly also in caves. The so-called
Darling Downs, not far from the Condamine, have
yielded a great number of these fossils. It was
here that Leichhard, among others, collected at
the commencement of his journey the remains of
the Diprotoclon, and considered them so little like
fossils, that he expressed the hope that he would
meet with living specimens of the same animals in
the interior of the continent.

In conclusion, we come again to the question
as to the relation between the American and the
Australian Marsupials, with regard to which, as
has already been said, the primitive earth gives
us no clue. Several peculiarities, more particu-
larly the completeness of the dentition, point to
the Didelphidse as the earlier branch. But there
is also another circumstance. According to Bar-
Owen, Extinct Mammals of Australia (London, 1877), with
131 plates.

108 THE MAMMALIA.

delcben's recent observations on the structure of
the tarsus or root of the foot in mammals and in
Man,1 the Didelphidae herein show most agreement
with the Lower Vertebrates. All the American
Marsupials (the number of which has been con-
siderably increased by the researches of Hensel, who
died at too early an age) possess the determining
bones which, it is true, are not altogether wanting
in the Australian species, but are very much modi-
fied, and thus point to a later differentiation. All
of the American species, says Bardeleben, are five-
toed. The larger forms, also those without the
isolated bony intermedium, and finally those with
a reduced metatarsus, are all found in Australia.
For this reason Bardeleben thinks himself justified
in maintaining it to be probable that America, and
not Australia, was the primeval home of the Mar-
supials. Hence, that the Australian Marsupials
differentiated after the continent became separated
from the rest of the earth, and that they there be-
came to a certain extent fixed forms.

If the enormous area of the Australian con-
tinent— of which Tasmania, New Zealand, and New

1 Bardeleben, ' Ueber das intermedium tarsi ' (Sitzungsbe-
richte der Jenaischen GesellscJiaft fur Medicin und Naturwissen-
schaft, 1883).

THE MARSUPIALS, OR POUCHED ANIMALS. 109

Guinea form a part, and which is so poor in Mam-
mals— be compared with any other corresponding
latitudes, the contrast in the fauna will appear most
striking. The eminent German naturalist Carl
Eitter, in his lectures on Australia,1 was, if I am not
mistaken, the first to describe this continent — not,
as is usually done, as the ' latest,' but as the * sta-
tionary ' continent, and as old-fashioned both as
regards fauna and flora. This uniformity resulted
in an entire absence of the most important outward
inducement to the formation of varieties : with a
moderate struggle for existence, a consequently
smaller progress in the functions of the organisms.
No Marsupial has shown itself suitable as a
domestic animal ; neither work, nor protection,
nor milk has been obtained from them. Their
flesh only, which is unpalatable to a refined taste,
was made use of by the nomadic primeval
inhabitants ; the latter were a very low race of
men who, in fact, could not advance beyond the
threshold of civilisation, because neither the neces-
sity for settling in certain localities (which goes
hand in hand with the taming and training of
animals), nor any inducement to cultivate the land,
was ever brought before them.

1 Which lectures I had the good fortune to attend.

110 THE MAMMALIA.

3. THE EDENTATA, OR ANIMALS POOR IN TEETH.

Gaudry tells us that the famous brain-anatomist,
Gratiolet, compared the Sloths to old men crawling
along heavily, with hands that had become im-
movable, and as having lost their teeth all but
a few pieces of cheek-teeth. Now if we take
these sloths in connection with the Ant-eaters,
Arrnadilloes, and scaly ant-eaters (which call forth
similar comparisons), and then endeavour to de-
termine the common character of the strange
company from a scientific point of view, we shall
find it easier to ask the question than to give a reply.
It is true that, as their systematic name indicates,
all are poor in teeth — i.e. have an impoverished
set of teeth, some even no teeth at all, and in most
cases only pointed, regularly formed cheek-teeth
without enamel; again, all possess limbs with
large claws; further, the brain is in all cases of
very moderate size, the surface of the larger hemi-
sphere being flat. However, this latter peculiarity
is met with in other of the lower orders of the
Mammalia, and upon a closer examination not
much importance can be attached to the certain
amount of uniformity of the toes mentioned above.
One sloth has three, another two, the Giant Sloths

THE EDENTATA, OR ANIMALS POOR IN TEETH. Ill

three and four toes, the Ant-eaters and Armadilloes
mostly five on the front limbs ; some are burrowers,
some climbers, some walk upon the soles of their
feet, others on the outer sides of their feet; the
Sloths and Ant-bears have hairy coverings, whereas
the Armadilloes and Scaly Ant-eaters are covered
by an armour of bone, horn, or scales. The
armadilloes and ant-eaters live on worms and
insects, the sloths are decided plant-eaters.

Even from a superficial consideration like this,
it is evident — and a careful study of the question
only corroborates the remark — that the living Eden-
tata stand in a wholly different relation among one
another from that of the members of other orders
of animals, with the exception, perhaps, of the Mar-
supials and Semi-apes. The certain something by
which they are connected, but which our system
of arrangement cannot specify in a few brief or
clear words, could not be definitely stated unless
we were acquainted with the early history of the
group.

Unfortunately, we do not know their early
history. Even the geographical distribution of
the few existing species points to a very remote
period. Were we to assume that the ancestors of
the Asiatic and African Armadilloes, the African

112 THE MAMMALIA

Ground-pig, and the American Ant-bears, Sloths,
and Girdled-animals were at one time allied, we
should also have to assume a connection between
the three continents. There has been no lack of
very bold combinations to bridge over the gap to our
undiscoverable friends — who, it is to be hoped, were
better equipped for a wandering life than they are
nowadays, and have been since the Tertiary, at
least — and also to the ostriches, which, owing to a
similar geographical distribution, are equally enig-
matical. But geology has, as yet, not been able to
say her yea to this. America alone shows a rich past
for the Edentata of the earth's most remote periods.
In Europe traces, at least, have been found which
justify the conclusion that where single individuals
of the modified forms lived, others also of the same
group must have existed contemporaneously or in
the preceding periods.

The comparatively large variety of Edentates
in South America is accounted for by the still
larger number of Diluvial species, some of which
were of gigantic size. Many inhabited the same
tracts of land which are at present the abode
of their evident successors, if not descendants.
Others we find pushed farther northwards, but we
cannot with certainty determine whether their

THE EDENTATA, OR ANIMALS POOR IN TEETH. 113

nearest relatives, in those days, lived in the southern
centre of distribution — where they continue to live
up to the present time — or whether the migration

Fio. 8. — Skull of the Giant Sloth. One-tenth nat. size.

After d'Alton.

from the north southwards was the origin of the
present distribution.

The limbs of our present leaf-eating Sloths are
most perfectly adapted for clutching hold of the

114 THE MAMMALIA.

branches of trees, and the animals are, by a peculiar
arrangement in the circulation of their blood, en-
abled to remain hours and days in the most un-
comfortable positions ; hence they have almost com-
pletely lost the faculty of moving along level ground.
The nearest relatives of the Sloth — i.e. of the
genera Bradypus and Clwlcepus — are the colossal
Megatherium and Mylodon, found in the Diluvial
deposits of North and South America. Of the
former we have an account, with illustrations, in
E. d' Alton's * Classic Monographies,' where it is
called ' the giant sloth.' He there says, that, com-
pared with its skeleton of fourteen feet in length and
seven feet high, that of the rhinoceros appears grace-
ful, the elephant light and slim, and the hippo-
potamus of good proportions. Its unusually broad
and bulky body has a very small skull (Fig. 8), and
is remarkably like that of our present Sloth. True,
the cheek-bone, which in the case of the Giant
Sloth is firmly attached to the temporal bone, is
not thus joined in our present Sloth (Fig. 9), but
in the case of both the cheek-bone shows a strongly
developed continuation that points downwards. The
teeth of the fossil animal, sixteen in number, are
compressed within the actual region of the cheek ; in
the existing species they stand more apart ; but in

THE EDENTATA, OK ANIMALS POOR IN TEETH. 115

both they bear witness to the peaceful habits of a
plant-eater, and the unmistakable agreement in the
type of skull leaves but little space for a brain,
even in the Giant Sloth.

But what a difference in the limbs! Of the
character of these limbs in the two species, Mega-

FIG. 9.— Skull of the Three-toed Sloth. Nat. size.

therium and Mylodon, and of the mode of life of
these animals as it has to be imagined from the
limbs, Owen gives an admirable account. We will
here quote his description of the Primeval Sloths
which supplements our knowledge of the nature
and habits of the living species, even though it
may not give any direct explanation of them.

116 THE MAMMALIA.

After a detailed account of the various parts of the
limbs, he says : ' The principle of viewing structures
and instruments, in reference to the work that they
do, is shown to be good in gaining insight into the
mode of life of extinct animals, in a striking degree
through its application to the skeletons of the
Megatheriods (Giant Sloths). The teeth of these
conform so closely in all characters with those of
the Sloths as to suggest leaves rather than roots to
have been their food. In the light, slender Sloths
the modifications of structure for climbing, cling-
ing, and living altogether in trees are carried out
to an extreme. In the colossal extinct kinds, the
foliage was obtained in a different way. The huge,
single claw on the hind foot l would be applicable
as a pickaxe to clear away the soil from between
the ramifications of the roots : a second claw 2 would
have interfered with such work. The foot is
organised to give great strength to that claw ;
dislocation of its toe is specially guarded against ;
the rest of the tarso-metatarsal structure relates
to the power of the foot to sustain superincumbent
pressure, with a position of the claw bringing its

1 This is the claw of the middle toe. The other toes appear
to have been furnished with a kind of hoof.

2 The reader who finds this explanation somewhat too odd
not forget that Owen is a decided teleologist.

THE EDEJSTATA, OR ANIMALS POOR IN TEETH. 117

side instead of its point in contact with the ground.
The bones of the thigh and leg are remarkable for
their massive proportions, for their thickness, and
especially their breadth in proportion to their
length : the femur in both Mylodon and Megathe-
rium would rank rather with the " flat " than with
the " long ' bones. These osseous columns were
needed to support the huge, heavy, expanded
pelvis. The iliac expansions are the chief con-
ditions of the other characteristics of this part ;
and they are unintelligible save in relation to ade-
quate extent of powerful muscles, especially those
arising from the crista ilii, the chief of which
muscles concentrate their force upon the fore
limbs. This indicates that these limbs were put
to some unusual work ; and the inferences from the
teeth and the hind claw lead to its recognition as
the pulling down trees and wrenching off their
branches ; but for these operations the pelvis must
have adequate fixity, and to the weight and strength
of itself and its supporting limbs there is added a
tail so developed as to serve as a third support and
give the pelvis the basis of a tripod. Without this
view of the function of the hind parts of the
skeleton, we can only see that the pelvis is so great
and, with its caudal appendage, so weighty as to

12

118 THE MAMMALIA.

require the massive proportions and structure of
the hind limbs, and, reciprocally, that these be-
speak a proportionate size and weight of the parts
to be sustained ; but why such development of
sustaining limbs and parts to be supported in
reference to any other action and way of life is
inconceivable. The excess of bone in the hind
part of the skeleton once recognised as relating to
the fixed point of attachment of muscular forces
working the fore limbs — to the exertion of power
adequate to prostrate a tree — arid the rest of the
bony organisation becomes intelligible. That of
the hind foot has been explained : the concomitant
extent of the muscular origin afforded by the broad
scapular plate, with its many ridges, crests, and
processes, is thereby accounted for. The necessity
of the firmness imparted to the shoulder joints by
the perfect clavicles abutting at one end against
a large " manubrium," at the other end against the
conjoined acromion and coracoid, becomes obvious.
The fore foot retained three huge claws to effect an
adequate grasp of the trunk or bough : for their
due and varied application the fore arm enjoys all
the variety and freedom of movements which an
arm terminated by a hand possesses. A tree being
prostrated and its foliage thus brought within

THE EDENTATA, OR ANIMALS POOR IN TEETH. 119

reach, every indication in the skull of the size,
strength, flexibility, and prehensile power of the
tongue harmonises with the foregoing teleological
conclusions. The Megatherioids, like the giraffe,
thus plucked off the foliage on which they fed.
In the ridged crowns of the grinders of the Giant
Ground- Sloth we discern the power of crushing
coarser parts — a greater proportion of twigs and
stems, e.g. of the foliage, than the diminutive Tree-
Sloths take. It needed only evidence of the occa-
sional occurrence of what might happen to a beast
in the fall of a tree which it had uprooted, to seal
the foregoing physiological inferences with the
stamp of truth : and the skeleton of the Mylodon
in the Hunterian Museum shows that evidence
above the right orbit and at the back part of the
cranium.'

Those who can agree with Owen's whole deduc-
tion as to the tearing down of trees will also accept
his ingenious explanation of the cracks in the skull
of the famous specimen in the Hunterian Collection
of the College of Surgeons.

But although this account and our observations
concerning the existing Bradypodae throw light
on the structure and habits of the fossil group,
they do not tell us anything about the real an-

120 THE MAMMALIA.

cestors of the living Brazilian Sloths. The ex-
pression so frequently used in illustrating the
relation, that the sloths of the present day are the
pygmean remains of the family which attained a
colossal development in the Diluvium, would be
wholly misunderstood were we to regard the
Bradypodae as crippled Megatherioids which had
taken refuge in trees. In both cases the limbs
have attained extreme formations which exclude
every thought of their having been transmitted the
one to the other ; and we are again referred to a
primary form that lies beyond all the palseonto-
logical discoveries yet made.

The existing Girdled-animals and the Diluvial
Glyptodons resemble one another less in structure
than in size. But also in the group of the burrow-
ing and grubbing Armadilloes (which live on worms
and insects) one is tempted to set too little value
upon the length of time necessary for their origin
than a careful consideration of the divergences
would warrant. Thus the Girdled-mouse, Chlamy-
dophoms, a native of La Plata, differs so much
from the girdled-animal proper, the Dasypus, in
spite of the most obvious relationship, that there
must be between them a whole series of transitions ;
and hence probably one or two geological periods

THE EDENTATA, OR ANIMALS POOR IN TEETH. 121

between them are necessary for the development
of these transitions.

In order to arrive at a right estimation of this
and of all the other similar cases which we
shall have to allude to later, it will he well to
explain our views by a graphic example. Let us
suppose that there existed by the side of our
present one-toed horse, a three-toed form — like
that of Hipparion — which possessed, in addition
to the middle toe (corresponding with the horse's
toe), other two toes, smaller, withdrawn from the
ground and which had reached a stage of entire
disuse. This is by no means a capricious idea.
For, in the same way as ' circumstances ' led to
the disappearance of the one-toed horse in America,
circumstances might have preserved the three-toed
form in Asia or Europe, somewhere by the side of
the races that were being transformed into a one-
toed family. But even granting the existence of a
three-toed animal, a non-scientific person would
scarcely realise the length of time necessary for the
deviation and for the formation of the existing form
of horse. Hipparion disappeared from the scenes as
early as the Upper Miocene, and yet our horse was
not what he now is, immediately before our present
geological formation, as is proved by the order for-

122 THE MAMMALIA.

merly considered identical with, it, and described
under the name of Equus Stcnonis. This matter
we shall have to enter upon more fully in a subse-
quent chapter. Although not extending farther
back than to the Miocene, the period necessary for
this reduction of the two toes and of the meta-
tarsals to last rudiments (splint bones), was one of
enormous length. And yet the modifications that
took place during that period in the horse's foot,
and the transformation of the dentition that accom-
panied the modifications of the foot, were but
trifling compared with the differentiations in the
group we are at present discussing (the Edentata).
There is one other point to consider as regards
the approximate length of the period. In the case
of the horse, the question was less about a new
formation than about parts that lapsed into dis-
use ; now such parts are transmitted with in-
credible tenacity through long periods of the earth's
history. It is evident that more rapidity is
shown in transformations where adaptation does
not create entirely new organs, but merely modifies
those already existing ; thus, for instance, where it
changes running feet into climbing feet, and in-
significant skin-ossifications into huge shields and
plates.

THE EDENTATA, OR ANIMALS POOR IN TEETH. 123

If, accordingly, we require a very considerable
length of time — one certainly extending back into
the Tertiary — for bringing the Armadillo and Gir-
dled-mouse back to one family, we shall require at
least as long a period for the development of the
branch of Glyptodons from the common stock.
Almost precisely the same latitudes in South
America where the existing Girdled-animals find a
home, gave shelter during the Diluvial period to
the various species of the gigantic Glyptodons.
Buenos Ayres possesses the richest collection of
these very perfect fossils. They have been
admirably described by Professor Burmeister,1 for-
merly of Halle, who some thirty years ago went
to reside in South America ; and the descriptions
could be made as complete as if he had been
describing the skeletons of some common existing
animal.

Glyptodon davipes measures 2*80 m. from the
snout to the end of the tail. Of these 1'50 go to
the huge shield which covers its back and sides,
forming one piece. The skull shows an unmis-
takable resemblance to that of the Sloths, not
only as regards dentition, but also in the pecu-

1 Burmeister, Annales del Museo ptiblico de Buenos Aires.
1864.

124

THE MAMMALIA.

liar formation of the cheek-bone; however, as
regards the structure of its limbs it keeps wholly
within the limit of the Armadillo group. The
animal obtained its food by burrowing and scraping,
probably hid in caves, and protected itself from
the attacks of the not very powerful Carnivora, by
drawing its head under its breast like the arma-
dillo, its back being protected by a shield similar

to that of a gigantic
tortoise, its head by a
helmet of bony plates,
while the bony rings
of its tail were anchy-
losed, and formed a
kind of tunnel or
arched bridge of bone.
The Ant-bears of
South America have
an ancestor in the

Glossotlterium. Another giant of Diluvial South
America — but without any living representatives
-is Toxodon, known to us by its skull, which
measures 0*60 metre; it possessed a more com-
plete dentition, but nevertheless shows affinity
to the Edentate type. Toxodon, owing to its
isolation, does not account for the existence of

FIG. 10. — Head of Glyptoclon cla-
vipes. One-tenth natural size.
After Burmeister.

THE EDENTATA, OR ANIMALS POOR IN TEETH. 125

any of its contemporaries or any portion of the
living animals, and only asks us to imagine round
about him, and back to his own clay, a wealth of
forms that cannot be conceived in too great a variety.
From the Tertiary strata of South America-
our knowledge of which, however, is very meagre
— we have no Edentates. In North America a few
forms, such as the Moropus (of the size of a tapir)
have been traced back to the Miocene. This fact,
and the frequent occurrence in Nebraska of the re-
mains of Giant Sloths from the transition period of
the New Tertiary to the Diluvium, induces Marsh
to dispute the prevailing idea that the Diluvial
Edentata spread from the area of their distribution
in the south, northwards ; he maintains that it is
more probable that they migrated from the north,
southwards.

•

Fossil remains of Edentata have only rarely
been discovered in Europe. We have the Macro-
therium from the Middle Miocene of Sansan
(France) with its peculiar retractile claws. To
judge from the character of its limbs, it might
have been a climber, but can scarcely have been
this, for, as Gaudry says, it cannot often have
come across trees strong enough for such exercises.
The inexhaustible beds of Pikermi (Upper Miocene)

126 THE MAMMALIA.

have furnished one huge Edentate, Ancylotherium.
Finally a few remains from the Upper Eocene of
Quercy corroborate what is demanded by our theory
and common sense. With this division of the
living world, we may be said, upon the whole,
to stand utterly helpless as regards geological
antiquity, in so far as the question refers to a
special proof for the origin of species, and the
perfectly justifiable proof of a general deduction is
not accepted.

4. THE UNGULATA, OR HOOFED ANIMALS.

The usual classification of the living mammals
furnished with hoofs into many-hoofed, double-
hoofed, and single-hoofed animals appears as
natural and self-evident as convenient. However,
it becomes utterly inapplicable and proves alto-
gether incorrect when tested by our present
scientific principles, and when we further consider
the palseontological material that has gradually
been acquired. Of no other group have such
numerous fossil remains been found, and in no
other have so many lines been evolved from the
earliest Tertiary periods, partly up to the present ;
hence the remark of a recent writer, that ' the
genus Horse is the true " show horse " of the theory

THE UNGULATA, OK HOOFED ANIMALS. 127

of evolution,' may truly be applied to the whole
order. All the animals of the present age have be-
come what they are, but in scarcely any other case
is the process of becoming so obvious, or the transi-
tion more perfect : the transition, that is, from the
less specialised dentition of the Omnivora to the
peculiar jaw of our horses and ruminants, the
disappearance of the toes of the five-fingered
primary-hoofed animals down to our two-toed
ruminants and one-toed horse.

The basis of the correct classification has long
since been given by Owen, who divided all the
Hoofed animals into odd-hoofed and pair-hoofed.
It is not the number of toes that is the characteris-
tic feature, but the distribution of the weight of
the body upon the outer parts of the legs, or, what
is the same thing, the relation of the lengthened
axis of the leg to the middle toe. The Odd-hoofed
animals (Perissodactyla) are those with either five,
four, or one toe, but where the lengthening of the
axis of the upper and lower arm, and upper and
lower leg, passes through the middle toe, whereby
the middle toe has to bear the main weight even
where we have a three, four, or five-toed animal.
And Paired-hoofed animals (Artiodactyla) are those
where the axis passes between the middle and the

128 THE MAMMALIA.

fourth toe ; hence these two toes are more active
than the side toes, and have an almost equal
amount to do in bearing the weight. They ac-
quire strength by this function, while the less active
toes gradually become useless and finally disap-
pear. We have already referred to the importance
of the specialisation of the teeth, and to the sim-
plification of the limbs produced by the reduction
and disappearance of the toes, as an advance for
certain functions. And it is self-evident that the
disappearance of the toes must, in a lesser or
greater degree, affect the middle part of the hand
and foot, the roots of the hand and foot, the bones
of the lower arm and leg, and also the muscles and
other soft parts of the limbs.

Kowalewsky has pointed out an exceedingly in-
teresting circumstance connected with the bones of
the hand and foot, and distinguishes inadaptive and
adaptive forms among the Hoofed animals, where
the toes are either partly rudimentary or have
completely disappeared. This explanation of Kow-
alewsky's throws some light upon the question
why so many lateral branches of the Mammalia
have died out, whereas previously we had to be
satisfied with the general supposition that these
were the very branches that had not survived in

THE UNGULATA, OE HOOFED ANIMALS. 129

the struggle for existence. The case is this : the
original five-toed extremity (compare above Fig. 1,
p. 36) has, in the second row of tarsals, one bone
for every toe. If the side toes become reduced,
one of two cases may then happen to the bones of
the second row : either
they become reduced
with the toe, or they
are retained for the
remaining toe ; i.e.
they adapt themselves
to the circumstances
of the limb which
changes with the toes
and add to its strength
and agility. The ex-
amples adduced by
Kowalewsky are, in Flo 1L__Left Fore-foot of the

Anoplotherium. After Kowa-
lewsky.

fact, very instructive.
In the case of the
Eocene Anoplotherium (Fig. 11), the first digit is
wanting up to the carpals, but the carpal bone
(1) belonging to it exists, only it is reduced and
is of no further use. Of the second digit the
shortened metacarpal (n) exists, as also the carpal
(2), but both are useless.
13

130

THE MAMMALIA.

Now if we compare the same part of the foot
of the Peccary (Fig. 12), the first carpal has
vanished with the first toe. The second toe, of
which our illustration shows the metacarpal (n),
is withdrawn from the ground as the lateral

toe, hence becom-
ing reduced, but its
carpal (2) has not be-
come a superfluous
appendage, as in the
case of Anoplothe-
riurn, it has entered
the service of the
third, one of the two
principal toes (in,
iv) ; it has adapted
itself to the new con-
ditions of its organisa-
tion that have gradu-
ally been acquired.

The illustration
shows that both animals are essentially the same
as regards the fourth and fifth carpals. In the
peccary the fifth toe is still attached to the fifth
metacarpal, as in the case of the second reduced
toe of the Anoplotherium, which has dwindled

FIG. 12.— Left Fore-foot of the
Peccary. After Kowalewsky.

THE UNGULATA, OR HOOFED ANIMALS. 131

down to a mere remnant of the fifth meta-
carpal. But it is of use almost exclusively to
the fourth toe, and has grown into one piece with
its neighbour, 4. Kowalewsky thinks that he may
safely affirm that the inadaptive forms like the
Anoplotherium had, as a rule, a very short term
of existence, and differentiated within narrower
limits ; and that the adaptive forms possessed the
more advantageous predisposition of being further
developed, as is shown by their preservation and
transformation up to the present time.1

The first incomings of the Hoofed animals are
as yet lost in the same obscurity as those of the
other orders ; they are found variously developed
as early as the Lowest Eocene strata. A single
genus, indigenous both to the Old and the New
World, possesses five toes on the fore and hind
limbs, but already showing an inclination to odd-
hoofedism, if we may use the rather strange ex-

1 Filhol has uttered a decided protest against the genus
Anoplotherium. It is said to be plentifully represented in the
Upper Eocene by a number of sub-genera and species. Filhol
asks us to consider that the sudden disappearance of the Ano-
plotheridae, without leaving identifiable descendants, may as well
be the result of emigration as of a general dying out. Still
Kowalewsky's opinion has the advantage of being not merely a
supposition, but one based upon a very plausible scientific
deduction.

132

THE MAMMALIA.

A

FIG. 13.— Corypbodcn. Eight Fore and Hind-foot. One-sixth
natural size. After Cope.

THE UNGULATA, OR HOOFED ANIMALS. 133

pression. The animal is called Coryphodon, and is
somewhat the size of a rhinoceros. The toes are
all complete (Fig. 13) ; but i and iv are strik-
ingly weaker, and in decidedly the strongest,
corresponding with the lengthening of the axis of
the shank. The form of the skull of this earliest
known Hoofed animal does not make any strange
impression, any more than do the limhs. The
full dentition (forty-four teeth) leads to the con-
clusion of its having lived upon different kinds of
food. But the brain — the circumference of which
can be gathered from well-preserved impressions —
shows an inferior type of organisation, owing to its
insignificant size and the smallness and the fiat sur-
face of the larger part of the brain. It is, in fact, the
lowest and most reptile-like brain known to us. The
diameter of the larger portion scarcely exceeds that
of the spinal marrow, the middle brain being the
broadest section. Further, the form and position
of the olfactory lobes remind one of the lower
vertebrates. The length of the hemispheres mea-
sures one fifteenth of the skull, their volume one
twenty- seventh of that of a tapir of the same size.
Hence the brain of the Coryphodon has more the
appearance of that of a lizard than of any existing
mammal. But, nevertheless, this and similar

134

THE MAMMALIA.

forms leave us very far from a proper knowledge
of the primary Hoofed animal. And the connection
between Coryphodon and the colossal Dinocerata

14.— Coryphodon. Skull with Brain. One-fifth nat. size.

After Marsh.

(which are confined to the west of the Eocky
Mountains) also appears very indefinite. We shall
again have to return to the Dinocerata.

THE UNGULATA, OR HOOFED ANIMALS. 135

The palaeontologist, therefore, meets with Odd-
hoofed animals (Perissodactyla) as early as in the
Lower Eocene strata, and distinct from the Pair-
hoofed animals (Artiodactyla). He can, in both
groups, follow a few lines up to the present, and
can thus construct the pedigrees of the existing
families, at all events in very probable outlines.
In addition to the above-mentioned general form of
specialisation — which received its fullest expression
in the ruminants and horses — we have a very
marked change as regards the predominance and
the variations of the group in the New Tertiary as
compared with the Post Tertiary periods. The
tapir-shaped and pig-shaped Thick-skinned animals,
which at one time swarmed among the moist
forests and marshy banks, decrease in number,
while deer, antelopes, and oxen become more and
more the inhabitants of the newer formations
of forest lands and of the grassy plains — or at
least the drier steppe-lands — which became possible
with the greater consistency of the newer con-
tinents. Deer, antelopes, and oxen have, since the
Pliocene up to the Present, steadily and very
strikingly increased in number of species, whereas
the Odd-hoofed animals have as steadily decreased.
As late as 1869 Rutirneyer — in special reference

136 THE MAMMALIA.

to the Hoofed animals — was able to maintain, there-
fore, that, 'in spite of our as yet knowing with
certainty only a very small portion of the fossil
animals, still it has come to seem at least probable
that not only the variety and very marked character
of the forms, but that the number of the species
also has continuously increased.' However, this
opinion requires modification since the discoveries
made in America during the last fifteen years,
which discoveries may, to a certain extent, be
classed with Filhol's discoveries in France. The
Hoofed animals teach us above all things, as has
already been said, that we live in a world zoologi-
cally very impoverished.

The fossil species which have not left any
living representative of their former existence will
receive only our second consideration ; but as this
very class contains most of the genera that must
be the primary forms of the present species, we
shall best attain our object by showing the links
which connect the mammals we have around us
with those of the primordial world, by starting in
a general way from the known Hoofed animals — as
a few of the highest and still blossoming off- shoots
of a mighty tree — and thence take a survey back
towards the roots.

THE UNGULATA, OK HOOFED ANIMALS. 137

Artiodactyla, or Pair-hoofed Animals.

The two main groups of the living Pair-hoofed
animals are the Pigs and the Ruminants. We have
an approximation to the pigs (above all in the form
of the molars) in the hippopotamus, which con-
stitutes a side group. The characteristic feature,
which is met with even in the earliest known
forms, is the peculiar formation of the crowns of
the molar teeth ; and we shall accordingly desig-
nate the Pigs as tuberculate-toothed animals or
Bunodonta ; the Euniinants as crescentic-toothed
animals or Selenodonta. In animals of the pig
species the enamel of the surface of the crowns
shows elevations. The almost four-cornered crown
(Fig. 15, to the left) shows a front and a back wall
(v, h), an outer and inner side, an outer and an
inner front tubercle (AI), and an outer and an
inner back tubercle (ai). The tooth varies in
accordance with this scheme. Elevations of the
enamel are met with also in the ruminant type,
but present the form of a crescent (Fig. 5, on the
right), and much deeper folds.

1. THE SUID.E, OR PIGS.

The Pigs are represented in Europe by the
widely distributed genus Sus, and a few others of

138

THE MAMMALIA.

lesser importance, in America simply by the
Peccary, Dicotyles. From Sv-s we can most directly
follow the series in its earlier forms, whereas the
hog-deer of Celebes (Babirussa) and the African wart-
hog (Phacochoerus) show peculiarities of dentition
which, in the Babirussa, have proceeded from new
and special adaptations ; and the Phacochoerus
seems to owe its existence to an unknown lateral
branch.

FIG. 15. — Representation of a Tuberculate Tooth and of a

Crescentic Tooth.

The head of the Pig is remarkably long. Its
mode of life has played a great part in forming
this elongated shape. This is evident from a com-
parison of the Wild Boar with the Domestic Pig, or
of an animal kept in a sty with an individual — even
of the same litter — that has had to seek its food
in meadows. The more the pig has to work with
its head, by burrowing, the more it stretches the

THE SUID^:, OK PIGS. 139

muscles of the neck attached to the back of its
head, and the more is the plastic part, which is
specially soft in the young animal, affected by
the mechanical influence and becomes elongated.
Further, the shape and length of the snout is the
result of the pressure experienced while the pig
is obtaining its food, but is especially connected
with the larger number and full series of teeth.

The dental formula ! is: i - c pin \ m --. The

lower incisors stand out almost horizontally, as
in the case of some of the plant- eaters, and are
adapted for cropping grasses in which the tongue
takes no part. The canines of the male animal de-
velop into fearful weapons, especially in the case of
the wild boar. The premolars are of an indefinite
character and of subordinate importance, both as
regards taking food and for chewing it. The
molars, on the other hand, both in form and
action, occupy a middle position between the cheek
teeth of the Carnivora and those of the decided
grass-eaters ; yet in structure, in spite of their
affinity to the latter, they show a closer resem-

1 The milk-teeth of the Pig consist of four cheek-teeth. The
first one is not replaced, but remains in its position for some
length of time, till after the three permanent premolars have
appeared.

140

THE MAMMALIA.

blauce to those of the Carnivora. They are adapted

not only for chewing but
for crunching food. Their
dentition is, in fact, that
of an animal living upon a
mixed form of food — one of
the Ornnivora.

In the structure of its
foot the Pig is very closely
allied to the Peccary, which
we have already mentioned
as an example of the so-
called adaptive animal form.
However, the Peccary has
advanced farther in the
adaptation of its tarsal bones
to the two principal toes
than the Pig, in whose case
both the second and the fifth
toe still almost wholly claim
the support of the carpals,
without thereby accomplish-
ing anything particular in
FIG. 16.— Right Fore-foot the way of standing and

of the Pig.

running. From the relation

between the carpals and rnetacarpals it is evident

THE SUTD^, OR PIGS. 141

that the Peccary (Dicotyles), by the simplification of
its limbs — which is advantageous for running — has
advanced farther than Sus ; it is, in fact, a better
runner than the Pig, and we are fully justified in
supposing that both animals will make still further
progress in this direction. They are, without doubt,
swifter runners than were their ancestors with their
less reduced feet, and a further advantageous re-
duction will depend only upon circumstances. The
inward disposition towards this exists, but I must
beg the reader not to confound the simple word ' dis-
position' with the dangerous word 'tendency,' the
play-wcrd of philosophers and one apt to lead over
to the idea of purpose. If, after many thousands
of years, the foot of the American Peccary and the
European Sus should have lost every vestige of its
second and fifth toes, this would be a perfectly in-
telligible, nay, a most obvious case of hornceogenetic
convergence. If, however, our Pig and Peccary
should no longer exist for the zoologists of the
future, they would most probably regard the anti-
cipated and distinctly two-toed feet of both animals
as having been inherited.

This consideration may now lead us to the ques-
tion as to the primary forms of our living Suidte.

The genus Sus is found only in the Old World, even
14

142 THE MAMMALIA.

as fossils, and extends back as far as into the
Middle Miocene. A powerful Boar is one of the
numerous fauna found in Pikermi. Its discoverer,
Gaudry, has given it the name of S. Erymanthius.
The line is continued through the strata of the
Eocene by the genus Palceoclmrus and Ghoerotherium,
still with, or rather already with, a dentition of the
Pig species, but still with less reduced, or, more
correctly speaking, still with a full number of toes.
Even Palceochoerus typus from the Lower Miocene of
southern France shows the characteristic teeth of
the genus Pig (Fig. 17) : on either side three incisors,
a good-sized canine (c), four premolars and three
molars. A still earlier form of the tuberculate-
toothed animal is Choerotherium, which still has four
toes almost equally developed. The ' ancestral line '
of Primeval Pigs is thus evident enough for those
who choose to follow it, and is more distinct than
many a human pedigree.

Among the cousins of this family who could not
maintain an existence, and whose position is, in fact,
somewhat doubtful, are Cliceropotamus, and also the
colossal animal Antliracotherium, from the Coal for-
mation, which attained the size of a rhinoceros.

America likewise possessed a line of pig-shaped
animals which may be traced from the Eocene up

THE

, OR PIGS.

143

to the present living Peccary, and, with the exception
of a few species, is one different from that of the
primordial world. In this series we find repeated
the transformations and reductions which we have
just followed. Marsh makes out the line from
the Eocene thus : Eohyus, Helohyus, Perchcerus,
Tinohyus, Dicotyles. Hence we still stand before
the unanswered questions, whether, to what extent,

FIG. 17. — Pala?ochcerus typus, Left Upper Jaw. Nat. size.

After Gaudry.

and in which direction (from Europe westwards?
from Asia ? or from America ?) the exchange took
place, as affecting the formation of the differences
of the species ? or whether the development was a
parallel one ; Choeropotamus to the Pig, Eohyus to the
Peccary? Geologists are pretty well agreed that
during the Earlier Tertiary period, up to the Lower
Miocene, the Old and New World were connected by

144 THE MAMMALIA.

land, and during the Later Tertiary as well. An
exchange, therefore, may have taken place, and
certainly must have taken place up to the Eocene
period, as is proved by the occurrence of Coryphodon
in Europe and America, and of Palaeotherium and
Anoplotherium in Europe and South America. But
for a long period, during the Miocene, there was no
connection either between North and South America
or between America and the Old World. Hence
during this period there must, in any case, have
been a further parallel development upon the same
basis, a parallel development of Pair-hoofed animals
with tuberculate teeth, where the reduction of the
toes, discussed above, was an advantage ; and the
supposition of an even wider case of convergence is
perfectly admissible from a scientific point of view.

2. THE HIPPOPOTAMUS, OR RIVER-HORSE.

The Hippopotamus has to be traced back to a
similar primary form, for it is the only living
representative of the Hoofed animals with tuber-
culate teeth which has preserved the old structure
of the limbs pretty well unchanged. • The still
uncut, rootless cheek-tooth (Fig. 18) somewhat
resembles a double mitre with a basal setting, which
in front and at the back passes over into a three-

THE HIPPOPOTAMUS.

145

sided shield, and has a wart-shaped protuberance
between the two halves both out and inside. Each
half consists of two almost three-sided tubercles,
which lie flat against the inner sides that are
turned towards one another. From this it is
evident that the enamel outline of the used tooth

Fio. 18. — Second Lower Molar of the River-horse, to the right.

Nat. size.

(Fig. 19) consists originally of two pairs, with the
basal line of the three corners turned towards one
another, and which do not coalesce till they have
been used for a long time.

The Hippopotamus has become almost an
amphibian in its mode of life; its skull and

146

THE MAMMALIA.

dentition show very little modification, and the
formation of its foot has remained very faithful to
the primary type from the Eocene, the lineal
descendants of which, unfortunately, cannot be
pointed out singly. The Eocene animals with
tuberculate teeth, and likewise the Early Tertiary
ancestors of the Euminants, had to dwell prin-

Fro. 19. — First Upper Molar of the Hippopotamus, to the right.

But little worn off.

cipally in waters and on marshy ground. Their
descendants adapted themselves gradually to life
on dry ground, and this is connected with the
advantageous reduction of the toes. The Hippopo-
tamus family has taken an opposite course, from
being an animal that liked the marshy soil of
the primeval forests, it has become almost an

THE HIPPOPOTAMUS.

147

aquatic creature, and accordingly has preserved
the completeness of hand and foot, the four toes
almost fully developed. In Fig. 20 we have the
root and middle portion of the right fore-foot, and
we will here use the terms generally given to this
part of the skeleton in Man and the higher

FIG. 20.— Hippopotamus, Eight Fore-foot. After

vertebrates : s (scaphoideum) = radiate ; I (lunatiun)
= intermedium ; p (pyramidale) = ulnare ; t (trape-
zoideum) = carpale 2; m (magnum or capitatum) =
carpale 3 ; u (uncinatum) = carpalia 4 + 5.

A one-toed hippopotamus in the natural course
of development is an impossibility. The gradual
reduction of the toes, as already said, can be con-

148 THE MAMMALIA

nected only with the drying up of marshy lands.
And if, by some extravagant flight of the imagina-
tion, we could conceive the existence of a one-toed
leviathan, the very fact of its possessing a one-toed
foot would be the cause of its speedy extinction.
As regards dentition also the hippopotamus shows
signs of being geologically very old. The skull of
the unwieldy creature reminds one of a clumsily-
formed box. The breadth and height of the muzzle
are produced by the enormous development of the
middle incisors and of the canines. All of these
teeth are furnished with roots that are not closed,
but open wide apart. It is certainly not impossible
that these teeth assumed this form first among the
nearer ancestors of the river-horse. But it is more
probable still that the disposition to assume this
form was a remote inheritance, and that it was
only by accommodating itself to feed on aquatic
plants that, as regards position and size, the teeth
have grown into such ugly but useful tusks.

It has been already stated that the river-horse
is the only representative of its family. This
remark requires some explanation ; for we have
not only the well-known and so-called Nile-horse,
which is distributed over a large portion of central
Africa, but there is a second species, only 5 feet

THE HIPPOPOTAMUS. 149

in length, which, among other things, is distin-
guished by the remarkable shortness of the face as
compared with the total length of the skull. This
animal, which is met with in Siberia, has been
classed apart from the hippopotamus as a distinct
species under the name of Chceropsis. As, more-
over, the dentition is not quite the same, this
separation may be allowed to pass ; but both
species are and remain ' river-horses,' and all that
has been said above applies to the smaller species
as well.

It is only quite recently that we have become
more intimately acquainted with a third species,1
the Hippopotamus madagascariensis, which, as re-
gards size — it became some 7 feet long while the
Nile horse attains 11 feet — fills the gap between
the two African species, and as regards skull and
dentition approaches very close to the Hippopot-
amus amphibius. Its occurrence is extremely in-
teresting, inasmuch as it leads from Africa over to
Madagascar, where its remains were found in
marshy deposits together with those of the colossal
bird JEpyornis. Its having been found in company

1 Goldberg, ' Undersogelser over en subfossil flodhest fra
Madagascar,' Christiania Videnskabs selskabs ForhandUngar,
1883, No. 6.

150 THE MAMMALIA.

with this bird, and the nature of the locality where
it was discovered, justify the expression of ' sub-
fossil ' which is given to the species. It lived on
the threshold between the Diluvium and the Pre-
sent. And even granting that Madagascar and
Africa were at one time connected by land, their
separation must, nevertheless, have taken place
early in the Tertiary, and accordingly the stability
of the genus Hippopotamus is also proved from a
geological point of view. It is not only the form-
ation of the foot that points to very ancient pri-
mary forms to be looked for beyond the Tertiary
period ; but the dentition also — which had special-
ised even before the separation of the family into
the African and the Madagascar species — has varied
only to a very small extent.

3. THE RUMINANTIA, OR CUD-CHEWING ANIMALS.

After setting aside the, at present, very subor-
dinate group of pig-shaped Pair-hoofed animals,
and the Hippopotamus, all the remaining forms
of this division belong to the Ruminants. As all
are, for the most part, lively and nimble animals,
they do not, while grazing, take proper time to
masticate their food sufficiently, but hurriedly stuff
their paunch full of provision and then retire to

THE EUMINANTS. 151

some safe retreat, where they assist the digestive
process by giving the grasses and leaves consumed
a subsequent crunching and chewing. The Rumin-
ants do not bite off the plants, but tear them off,
in doing which the tongue plays an important part
as an organ for grasping, especially when long
grasses and branches have to be dealt with. In
this mere tearing off of grasses, &c., the incisors of
the upper jaw can be dispensed with ; it may be
said that with the development of meadow plants
and pastures, these teeth have in course of time
become superfluous. Only animals of the Camel
species show rudiments of the upper incisors, and
in addition to this case, canines have been pre-
served by the musk-deer. The crowns of the molars,
as a rule, show two transverse ridges, and, moreover,
the upper and lower molars fit in such a manner
that they can glide over one another from right to
left and also in a horizontal manner, as may be
seen in any ox or sheep * chewing the cud.' This
movement of chewing is rendered possible by the
condyle of the lower jaw not being sunk into a
transverse socket of the temporal bone, as in the
case of the Carnivora, or into a furrow running
parallel with the axis of the skull so as to move
backwards and forwards, as in the Rodents, but by

152 THE MAMMALIA.

being allowed free play upon an almost level, or
even a somewhat raised surface.

All Ruminants possess the above-mentioned
typical molars with the enamel crescents running
in the direction of the longitudinal axis of the
skull, which, of course, present a very different ap-
pearance— within the boundaries of the generic
characteristics — according to age and wear. Fig.
21 shows an, as yet, uncut fourth right molar of
a calf as seen from the front and the inner side.
It seems to consist of two almost quadrilateral
prisms, both terminating on the outer and inner
side, in two curved flaps (A-I and a-i). All the
surfaces, which pass over into various curves and
folds, one within the other, and are lost in the interior
of the tooth, consist of the, as yet, imperfect and
still somewhat soft layer of enamel. Below it is
the dentine, which is likewise just beginning to
develop, and round about in the depressions, between
A and i and a-i, we find the incomings of the
cement which is still a membraneous formation.
Now, if we take this embryo tooth and compare
it with the polished edge of one of the already cut
front teeth (Fig. 21, n), we shall at once obtain a
clear idea of the relation of the enamel folds and
edges of the molar of a full-grown animal. The

THE KUMINANTS.

153

transverse ridges, which fit into the depressions or
transverse valleys of the opposite row of teeth,
remain throughout life, even though, at a later age,
they may become more and more rubbed off and
level. The crescents, which become filled with
cement and are encased on the outside by enamel,
on the inside by dentine (tooth-bone), A, i, a, i, are

FIG. 21.

I. Right upper molar of a calf before it has cut the gums; i, inner sMe ;

A, a, the outer lobes of enamel ; /, i, the inner lobes.

II. The right molar of a calf that has cut the gums, artificially ground; from
behind and the outer side.

the transverse sections of the flaps of the same
name ; B and b are the arched-shaped spaces which
likewise become filled with cement, and were ob-
viously larger in the thin-walled, uncut tooth. If
we weigh the different possibilities of the folds of
the outer walls, the form of the crescent, the develop-
ment of the side folds and pillar-shaped processes,
15

154 THE MAMMALIA.

we come to understand the great variety which dis-
tinguishes the Selenodonts among one another, and
which becomes all the more marked, the more ob-
stinately the characteristic form is preserved.

But since Kowalewsky's classic works there can
be no question that the peculiarities, connected with
the reduction of the limbs, are testimonies at least
as distinctive and trustworthy for the Present and
the Past.

The majority of the living Ruminants are divided
into the large families of the Deer, the Antelopes,
and the Oxen. The last two, as horned animals,
are more closely allied to one another than to the
deer. The goats and sheep are closely allied to
the antelopes. Apart from all these we have the
Camels, to which we shall first direct our attention,
for, at least as regards dentition, they have pre-
served a higher geological antiquity than the others.

4. THE CAMELID^, OE CAMELS.

When Riitimeyer calls the llama ' a late offshoot
of the Eocene Anoplotherise, and as originating first
in America,' he gives a proof of the utter uncer-
tainty which prevailed about ten years ago as to
the position and historical development of the two
species which, since Buffon's day, had been regarded

THE CAMELS. 155

as belonging to one another. Of the two species of
camels the one with two humps is assigned to Cen-
tral Asia; the other has been distributed over a
large portion of Africa by Asiatic nomads, and
represents a peculiar mode of life. The llama
'vicariates' for them. The hoofs are small, but
the foot has a broad horny sole ; the skeleton of
the foot is that of a true Ruminant. The camels
differ from all the living Ruminants by the total
absence of horns and by a fuller dentition ; for
they not only possess strong sharp canines, but an
incisor in the mid jaw-bone, somewhat to the side.
All the other Ruminants, without exception, have
lost their upper incisors. On this account, and
because of the superficial resemblance in the form
of the skull with that of the horse, camels were
formerly classed as a group standing midway be-
tween the horses and the two-hoofed animals ; this,
however, is an unwarrantable conjecture. American
investigators have, on the other hand, now made
us acquainted with a wThole series of primeval
forms, according to which the camel appears to be
a very old branch of the Selenodonts.

Marsh gives us the result of his own and of
Leidy's observations thus : * A most interesting
line, that leading to the camels and llamas, sepa-

156 THE MAMMALIA.

rates from the primitive selenodont branch in the
Eocene probably through the genus Parameryx. In
the Miocene, we find in Poebrotherium and some
nearly allied forms, unmistakable indications that
the cameloid type of Ruminant had already become
partially specialised, although there is a complete
series of incisor teeth, and the metapodial bones
are distinct. In the Pliocene the camel tribe (in
America) was, next to the horses, the most abun-
dant of the larger mammals. The line is continued
through the genus Procamelus, and perhaps others,
and in this formation the incisors first begin to
diminish and the metapodials to unite. In Post-
Tertiary we have a true Auchenia represented by
several species, and others in South America, where
the alpacas and llamas still survive. From the
Eocene almost to the present time North America
has been the home of vast numbers of the Camelidae,
and there can be little doubt that they originated
there and migrated to the Old World.' *

1 Cope, in 1877, gave a fuller account of these opinions. The
Miocene Poebrotherium possesses of grinders p. 4, m. 3. The two
elongated metapodials have not coalesced ; seven tarsals. Then
comes Protolabos still with p. 4, m. 3 ; the last molar is more
prismatic. The incisors also are still there in full number, but
fall out readily. Procamelus is the first to show incisors like
our present camel, yet still p. 4, m. 3. The side rudiments
of the metatarsals of Po&brotherium have disappeared, hence the

THE CAMELS.

157

Nothing can well be said in opposition to this.
Our illustration below (Fig. 22), gives the upper

FIG. 22.— Auchenia hesterna. Second Molar of the Left Upper
Jaw. Nat. size (after Leidy).

molar of one of those Diluvial llamas, the Auchenia
hesterna, in the natural size.

trapezoid. The metatarsals have coalesced and become the

A Cf q

' canon-bone.' Then comes Pliaiiclienia with - . cheek-teeth,

o — o

o _ q o Q

Camelus, , Auchenia \ ' .

2 — o 1 — o

A more and more con-

tinuous delay in the formation of the teeth is observed ; tho
teeth eventually no longer cut the gum, and finally disappear
completely, a process which is repeated in many other lines.
The occurrence of the llama in South America shows that the
causes which led to its extinction in North America did not
exist in the southern continent.

158 THE MAMMALIA.

5. THE CERVID.E. — DEER AND THEIR KINDRED FORMS.

Kiitimeyer, in his ' Natural History of the Deer,'
when speaking of the characteristic features that
distinguish the various forms of deer, maintains
that the antlers are periodical, and that they are
attributes confined to the males of the species.
In looking for the relationship between the forms —
principally in the female skull, as in the case of the
Kuminants — he finds the character of the deer (as
compared with the antelopes and oxen) to consist
in the very elongated, almost cylindrical shape of
the skull. This is caused by the great length of
the olfactory tube with a lesser height of the toothed
portion of the upper jaw. The skull is elongated
and, as compared with the facial part, is less
voluminous than in the case of the horned animals ;
the brow is less of an abrupt incline, the axis of the
skull straight. The character of the head of the deer
may, of course, be thus described, and Eiitimeyer
has endeavoured also to characterise the antelopes
and oxen. Still, it cannot be denied that the
antlers, nevertheless, play a very great part, and
that their existence is of decided importance in
the classification of the deer.

The common Eoe and Eed Deer furnish us with

THE CEPVID^E, OR DEER. 159

two examples of very different degrees of develop-
ment in the antlers of single species; and by
observing the annual changes of the antlers we can,
with almost certainty, trace the different stages
attained by the various species with less fully
developed antlers. The first sign of the coming of
th3 antlers in the calf, is a thickening and pro-
truding of the frontal bone, the incomings of the
permanent base of the horn. Between it and
the upper layer of skin are then formed the
beginnings of the actual antlers — ossifications of
the skin — which soon coalesce with the frontal
process, dry up after completing their growth, and
fall off after pairing time. The antlers of the first
year — the stem or beam — consist of a pair of simple
stumps with the circular ridge of bone called the
burr. The following years furnish the branches or
tynes.

This development of the antlers in the indivi-
dual case of the red deer, Eiitimeyer compares with
the antlers in the historical and geological succes-
sion of stag- shaped animals, which in the Lower
Miocene are still without antlers. In the Middle
Miocene of Sansan and Gtinzburg, and in the
Upper Miocene of Eppelsheim, we first meet with
an animal that is almost, but still not completely,

1GO

THE MAMMALIA.

il

a stag. Frontal protuberances very elongated,

beams with single branches are
there, but no burr (Fig. 23).
The genus has been described
under various names, as Dicro-
cerus, Prox, Procervulus. The
tynes are often found broken off,
and it cannot be said with cer-
tainty where accident ends, and
the regular periodical casting off
has begun. It would seem as if
the casting had become estab-
lished from the irregular occur-
rence— partly the drying up of
the skin and the brittleness con-
nected with this.

Eiitimeyer observes that it
is difficult to distinguish the
primary stags from the primary
antelopes, and that perhaps the
North American prong-horned
antelope which, curiously enough,
casts its horns annually, must be
traced back to those indefinite

One-half nat. size. primary forms> Cope had made

the same observation in 1877 when he wrote : ' The

FIG. 23.— Prox fur-
catus. Left antler.

THE CEKVIDJE, OR DEER. 161

genus Antilocapra is related to the Dicrocerus by
its pronged horns and the hairy covering of skin
which constitutes the immature stage of the horn-
sheath.' The Procervulus mentioned ahove was a
widely distributed genus in the Miocene period, as
is proved by the discoveries in New Mexico and
Nebraska. The genus Cervulus, which is dis-
tributed over both the Old and the New World in
about eleven different species, must be regarded as
a diluvial remnant of the genus Procervulus, by
the side of the more modern family of the Deer,
which show a further advance in the development
of their antlers. The best known representative of
the genus is the Muntjak (Cervulus muntjac) in
India and the Sunda Islands.

In the Deer, as in the case of most of the living
pair-toed animals, the two metatarsals which sup-
port the two fully developed toes have coalesced
into the so-called cannon-bone. Their limit is
indicated by a more or less distinct longitudinal
furrow on the front side, frequently also by a
deeper indentation in the lower joint. We never
meet with complete metatarsal bones for the two
outer toes that are removed from the ground. The
modifications which prevail in this respect, within
the group, appear of very little importance and

162

THE MAMMALIA.

interest when considered by themselves, but when
taken in connection with the geographical distribu-
tion of the animals, are of great significance. As

FIG. 24.

A. .Left fore-foot of the Red Deer. B. Left fore-foot of the common Roc.
c, Cannon-bone; m, metacarpals ; p, upper phalange. C. Second row of
tarsal and metatarsal bones of the Gelocus. After Kovvalewsky.

examples of this we may take the red deer and the
common roe (Fig. 24). The rudimentary toes in
both cases consist of three phalanges. In the red

THE CERVIDJE, OR DEER. 163

deer the first of these is smaller than the other
two, whereas in the roe the first one is of the pro-
portionate size. Now this arises from the fact that
the rudimentary digits of the deer have become
entirely detached from the metacarpals, and that
only the rudimentary upper end of it remains
(A, m). The roe still possesses the lower portion
of this bone (B, m) and, moreover, in connection
with the first phalange. The red deer is a * plesio-
metacarpal ' cervide, the common roe a ' tele-meta-
carpal ' cervide. All the thirty-nine known species
of Cervidae, confined to the Old World, are con-
stituted like the deer with the exception of the two
species of roe and the hornless Hydropotes in
China, with which we have only recently become
more intimately acquainted. These three latter
species, however, as regards the construction of
foot, are allied to the American deer. Of the
twenty American species with tele-metacarpals, one,
however, the Wapiti (Cervus canadensis), is not
related to the others, but to the Europe-Asiatic
group.

From the formation of the foot, therefore, we
find an almost perfect means for distinguishing the
specise. And this leads to the very natural supposi-
tion that the American deer developed in the New

164 THE MAMMALIA.

World, and the Europe- Asiatic species in the Old.
It is only the ancestors of the Roe and the Hydro-
potes that must not be looked for in the Old World ;
they are scattered members of the group from the
other side of the ocean, like the Canadian species
which, in the days when the two continents were
connected by land, separated entirely from their
Europe- Asiatic cousins. It is found in the Qua-
ternary strata of Europe, e.g. in those of Louverne,
near Le Mans, where it lived as a separate family
by the side of the red deer, but soon afterwards,
for some unknown causes, vanished from this
locality and reappeared in the New World.

The reduction of the side toes and the dis-
appearance of the one or the other ends of the
metacarpals took place after the still four-toed and
geologically older stag-shaped animals had acquired
antlers. This may have been the course taken
by their development, unless we are to assume
that the antlers appeared in different localities as
a parallel formation, yet not till after the separation
of the older hornless Euminants, which likewise
showed a reduction of the limbs spoken of above.
The latter case is very probable, and must be
drawn into the circle of combinations, for in Gelocus
we have become acquainted with a very ancient

THE CERVID^E, OK DEEI*. 165

Ruminant of this kind, out of which both plesio-
metacarpals as well as tele-metacarpals forms might
have developed. Gelocus is an adaptive species of
Euminant from the Eocene. The skull as yet
scarcely shows the character of the ruminant, hut
the molars are already reduced to J- , whereas other
genera of the same age show \. The two principal
metatarsals (Fig. 24, c, in, iv) have coalesced
along almost their entire length ; the metatarsals
of the side toes have, however, disappeared in the
centre (Fig. 24, n, v), and only the lower and
upper ends remain (111). Animals of this kind
might have descendants with feet of the Deer
species, another with feet like the Eoe. At all
events, deer and roe, both of these well-known
denizens of our forests, have been strangers to one
another from very remote times, strangers as
complete as the Canadian stag (the Wapiti) is to
all the other American Cervidse.

An intermediate position between them is occu-
pied by the Elk and Eeindeer. Both are circurnpolar
species, and both, as regards construction of the
foot — as tele-metacarpal species — are allied to the
deer of the New World, the reindeer, moreover, by
the form of the nasal cavity. Our material is at
present too fragmentary to enable us clearly to

16

1G6 THE MAMMALIA

survey both sides. But all of these observations,
which we owe principally to Sir Victor Brooke,1
confirm Biitimeyer's remark that the form and
development of the antlers can only very cautiously
be made use of as a means for a strict classification
of the Cervida3.

Even though animals with antlers are met with
as early as the Miocene, still the more complete
development of true Deer belongs to very recent
periods, and this explains their geographical dis-
tribution in the main. In addition to the circum-
polar reindeer and elk, Eiitimeyer, agreeing with
Brooke, reckons twenty species to America and
thirty-nine to the Old "World, many of which are
certainly doubtful. An exchange between East
and West seems evident, and yet, as we have seen,
it was extremely limited. The remarkable want of
deer in Africa beyond the desert, would have to be
explained, with Wallace, by the fact that there must
have existed obstacles almost insurmountable to
the animals when they first began to distribute ;
on the other hand, antelopes and even giraffes
had either already passed the open road south-
wards, or, owing to their organisation, had gra-

1 Brooke, ' On the Classification of the Cervidas,' Proc. Zool.
SOG. 1878.

THE CERVIDJE, OR DEER. 167

dually overcome the difficulties presented by the
desert.

Zoologists have always classed the Musk Deer
and the Dwarf Musk Deer (Traynlidce) with the true
stags, although they are hornless animals. In
doing this they have allowed themselves to be led
by the general impression that the possession of
antlers is not determinative of the relationship ;
this had already been affirmed by Alphonse Milne-
Edwards in 1864, and has been proved by their
connection to the fossil forms that have now been
brought to light. From these annexed groups the
Hycemosclms aquaticus, which lives on the west
coast of Africa, is of great importance as the con-
necting link between the present and the remote
past. Our Figure 25, A, gives the left fore-foot of
this animal. Hycsmoschus is also a decided two-
hoofed animal, although the two middle metacarpals
(in, iv) are entirely separate, and although the
two outer metacarpals (n, v) are perfectly com-
plete and the two lateral toes are developed and
connected. Hycemosclius thus proves itself an
adaptive form, inasmuch as the two toes that are
no longer of use have ceded their right to the
tarsals, to the principal toes, and thus increased the
strength of the latter. The skeleton of the fore-

168

THE MAMMALIA.

foot of the Hyamoschus appears a slight modifi-
cation of that of the Miocene Hyopotamus (Fig.

FIG. 25

A. Left fore-foot of Hyjemoschus aquations.

b. Same foot of Hyopotamus. After Ko wale \vsky.

THE CERVID^:, OR DEER. 169

25, B). There both outer toes are still somewhat
longer and stronger. Trapezoid and os magnum
have not yet coalesced ; the metacarpals n and v
are still connected with the carpals. Upon the whole,
however, the differences between the living and the
Miocene representatives of the pair-hoofed group
are so slight that Hycemoschus may be called a
surviving form of primary ruminant.

The hind limbs of the Hycemosclms are more
changed than the front limbs, owing to the two
principal metatarsals having almost completely
coalesced. A greater reduction of the hind limbs
is often met with : for instance, the peccary has
only one rudimentary toe on its back foot, whereas
there are two on the fore-foot. This difference in
the construction of the front and back limbs is, we
think, to be explained by the greater amount of
work which the hind legs have to accomplish ; for,
as was said above, we look upon a reduction of this
kind as an advance in the power of the adaptation.
But, while we are naturally led back from our
present Deer and TragulidaB to those early four-
toed Hyopotamidaa, we do not in any way mean to
affirm that up to the Middle Tertiary all animals of
the Ruminant group without horns or antlers
possessed the full number of four toes. On the

170 THE MAMMALIA.

contrary, it is found that the Anoplotherium from
the Eocene vof the Paris limestone, which has left
no descendants, shows scarcely any traces of the
second and fifth toes ; and by the side of the
Hyopotamus, with four-toed feet, there existed the
distinctly two-toed Gelocus,1 whose extremities are
almost as much reduced as the Deer ; and the same
is the case with Diplopus. It would be rash to
attempt to determine, among all these varied forms,
which was the actual and definite primary form for
the Deer or any other living group of the Rumi-
nants ; still, any attempt to explain the striking
relation between the past and present forms, other-
wise than by means of the theory of descent and
in accordance with Darwin's principle, cannot be
expected from us. The share which homoeogenetic
approximation may have taken in this connection
has already been discussed.

The same result is obtained by the condition of
the teeth; and, as in the case of the limbs, the
teeth must not be examined in the Deer by them-
selves, the whole group of Ruminants must, first
of all, be compared with the fossil forms.

Among our living Hoofed animals the Giraffe

1 Filhol, ' Mammif&res fossiles de Konzon, 1882,' Gelocus,
Ancodus, and others ; their Relation to Hyopotamus.

THE CERVIDJE, OR DEER. 171

occupies a perfectly isolated position. Apart from
its strange shape — the result of a lengthening of the
vertebrae of the neck— and of the different lengths
of its fore and hind limbs, descriptive zoology
has very rightly laid stress upon the frontal deco-
rations which adorn both sexes, and which have
been said to be neither horns nor antlers. The
two horn-like unbranched protuberances are
covered with a hairy skin which never dries up as
in the case of the deer, and hence they do not fall
off periodically. These skin-covered bony protuber-
ances cannot, however, be compared to the bony
protuberances of the Oxen, as might be supposed,
that is, to the processes of the frontal bone covered
by the horn sheath. On the contrary, like the
antlers proper, they begin as ossifications of the
skin, and grow precisely in the same manner as
antlers, but never become perfectly attached to the
frontal bone. In order briefly to distinguish the
character of the formations it may be said that —

Hollow-horned animals have frontal processes
without antlers,

The Deer processes with antlers,
The Giraffes antlers without processes.
Hence Eiitinieyer calls the giraffes ' a most fantastic
form of deer.'

172 THE MAMMALIA.

Like the lions and gazelles, the giraffes of
Africa are probably immigrants from the South of
Europe. Among the Mammalia buried at Pikermi
is a species, Camelopardalis attica, almost the same
size as the African variety. Unfortunately its skull
is not known. The disproportion between the
hind and fore limbs seems to have been even
greater in the fossil species. Further traces lead
us to the Siwalik hills in India. Numerous re-
mains have enabled Gaudry to restore the com-
plete skeleton of a genus closely allied to the
giraffe — the Hclladotherium — which lived in herds
in Miocene Attica, and owing to their great size
must have been characteristic figures in the land-
scape of the primeval world.

It was customary to class with the above the
colossal Indian Sivatherium, which possessed a pair
of simple horns in front, and a second branched
pair. And yet our conjectures with regard to its
affinity with the Giraffe are uncertain, and Biiti-
meyer thinks that the Sivatherium points as much
to the Antelopes, as the Giraffes to the Deer. Our
knowledge of two other Indian species, the Brama-
therium and Hydaspitherium, is as yet so fragmen-
tary that it is wiser not to make any conjecture
as to their relationship.

THE ANTELOPES AND OXEN. 173

The Giraffes stand close to the Deer, not because
they have branched off from the deer, but because
the unknown ancestors on both sides showed a
disposition to certain reductions and convergences
of a similar kind.

6. CAVICORNIA, HOLLOW HORNED ANIMALS. — ANTELOPES

AND OXEN.

The horned Ruminants, which are grouped
round the Chamois, Sheep, and Oxen — and hence
furnished with horn-cores rising from the frontal
bones, and a horn sheath — would appear to any-
one to form a natural group. And even those who
have not studied the subject would undertake to
distinguish a Gazelle, as the representative of the
Antelopes, from an Ox. The gracefulness of its whole
appearance, more particularly of the horns, the
smallness of the head, the slender shape of the legs,
sharply distinguish the Antelopes from the Oxen,
whose horns stand at the outermost point of the
brow, whose skull is unwieldy in form, and whose
legs (in keeping with the rest of the skeleton) are
anything but graceful. However, when we examine
the different families in any good collection, we
shall find that by the side of the prevailing type
of the slim antelope, there are various kinds of
cow-shaped forms, with head and limbs in no way

174 THE MAMMALIA.

resembling the Gazelles, yet almost all with horns
strikingly different from those of Oxen. Finally,
the gnu completely breaks down any systematic
boundary, for by the form of its hindquarters and
tail it resembles the horse. And into this group
sheep and goat have to be brought. We can, it
is true, distinguish them among one another by
the characteristic traits of the family ; for instance,
by the peculiar form of the skull. The ram, owing
to the form and solidity of the nasal, lachrymal,
and frontal bones, is able to give and to receive
those tremendous blows of forehead against fore-
head which would break the skull of the male
goat. But there are sheep with goat-like horns;
and an animal that is clearly a sheep from the
form of its skull has up to within recent times
been called the musk ox.

These resemblances — it may positively be as-
serted— do not proceed from recent derivation or
crossings, but must be traced back — except in the
case of the closely allied Sheep and Goats — to con-
vergences. Moreover, the Antelopes — the most
varied group of the living Euminants — have not
been so carefully studied in connection with their
nearest fossil relatives as the Oxen.1

1 Kiitimeyer's valuable investigations of this group may here
be mentioned.

THE ANTELOPES AND OXEN.

175

The distinguishing feature in the skull of the
ox is most strongly developed in our domestic

FIG. 26.— Skull of a Short-horned Bull.
/.Froutal bone ; «, nasal bone ; o, upper jawbone ; z, mid jawbone.

176

THE MAMMALIA.

animal belonging to the genus Bos (Fig. 26). Here
the parietals are pushed completely back from the
top, or all but a small portion, to the abrupt
incline at the back of the head. From a front
view, or looked at from above, they cannot be
seen at all. On the other hand, the frontal
bones (Fig. 2G) form great plate- shaped cover-

Fm. 27. — Skull of the Gazelle (Antelope arabica).
t, Parietal ; /, frontal bone ; z, mid jawbone.

ings to the forehead, and the bony processes rise
upon their outer edge. As compared with the
skull of an antelope (Fig. 27), the skull of our
domestic ox has reached the extreme of a formation
which is still repeated pretty perfectly in the
individual development of the calf to the cow. It
consists in this : that in the calf the skull is still

THE ANTELOPES AND OXEN. 177

rounded, the frontal part is not, as yet, elongated,
and the crown portion still forms actually a part of
the upper covering of the skull. Only upon the
appearances of the horn-cores and the lengthening
of the frontal bones do we find the first indication
of the abrupt rising up of the main back wall.
The calf is therefore still antelope- shaped as
regards the formation of its skull, as is shown in
Fig. 27, where the whole length of the parietal
bones are still to be seen from above, and the horn-
cores do not occupy the backmost or outermost
corner of the frontal bones. Sheep and goats also
keep within the boundary of this type of the Ante-
lope family. Calf and cow, therefore, again corro-
borate the most important proposition of our doc-
trine of descent : that the individual development
is an abridged repetition of the historical develop-
ment of the species.

On the accompanying table of Eiitinieyer's we
have the sub-families of the Oxen classed according
to the form of their skulls. It begins with the
buffaloes, which, as regards skull and the position
of their horns, have deviated least from the Ante-
lopes, and closes with the domestic ox, which has
differentiated the most. We gather from this

table — which contains the quintessence of all the
17

178

THE MAMMALIA.

TABULAR VIEW OF THE FOSSIL AND LIVING OXEN
(AFTER RUTIMEYER).

Miocene ? .
Pliocene

Pleistocene

Living

I. Bubal ina

Bubalus

caffer

antiquus

brachyceros

Buffelus

sivalensis

indicus (domestic

ox)

sondaicus

Pallasii

Probubalus

triquetri-

rostris

Amphibos

acutiformis

antelopinus

(Anoa) celebensis

II. Portacina

Leptobos

Falconer!

Strozzi

Frazeri

[II Bibovina

Bibos

etruscus

PalfEO-

Gaurus

Gaurus

? GavaBus

sondaicus

indicus

grunniens (Yak)

[V. Bisontia

Bison

sivalensis

priscus

europaeus

latifrons

americanus

V. Taiwina

Bos

planifrons

namadicus

primigenius

taurus f. primi-

genius

f. trochocerus

investigations made on the subject — that our know-
ledge is still meagre enough, inasmuch as at the
Pliocene stage — where true oxen are first met with
— we already find the transition from the buffalo
to the ox in its narrower sense. The different

THE ANTELOPES AND OXEN, 179

European oxen * have all, perhaps, to be traced back
to the Diluvial Urus, or wild. bull (Bos primige?iius),
and the races which branched off as early as the
Diluvial period.2 If, in accordance with the above
standpoints, the skull of the domestic ox, of the bison,
the yak, and the Indo-European buffalo, be com-
pared with that of the antelope, it will be found that
the resemblance to the antelope will become more
and more apparent. Thus the bison (Fig. 28) is
still so like the ox that, as we shall see, it might
be doubted whether one of our races, the Dux
cattle of Eastern Tyrol, is to be traced back to the
wild bull or to the bison. On the other hand, the
Anoa of Celebes, which Eiitimeyer calls the Probu-
balus celelensis, is indeed still an ox in all its out-
ward characteristics (' the dwarf of the ox family '),
but is a complete antelope as regards the position
of its frontal and parietal bones (Fig. 29). This
agreement in the outward parts must scientifically

1 The three most important races of oxen which have to be
traced back to Bos primigenius are :

Brachyceros race . . . Appenzell cattle
Primigenius race . . . Holland cattle
Frontosus race .... Bern cattle

2 A good survey of the investigations and opinions as to the
origin of the domestic ox is given in Friihling's Landwirth-
schaftlicher Zeitung, Feb. 1878; Pagenstecher, Studien zum
Ur sprung des Bindes.

180

THE MAMMALIA,

be regarded as a convergence, in the skull as an
homology.

Fir,. 28.— Skull of the Bison americanus. After Wilckens.

It has been stated that the separation of the

THE ANTELOPES AND OXEN.

181

antlered from the horned animals is met with first
in the Miocene, or, in other words, that deer and
antelopes are difficult to distinguish before that
period. Later we have the branching off of the
oxen, but we cannot closely define the point of

FIG. 29.— Skull of the Anoa. After Riitimeyer.
*, Parietals ; /, frontal bone.

attachment. In the Lower Miocene and Eocene,
the Ruminants are represented by distinctly pair-
hoofed and crescentic-toothed animals, which,
although absolutely without horn-cores on the
frontal bones, are distinguished by a very full
dentition without gaps, some being without the

182 THE MAMMALIA.

prominent canine teeth which serve the others as
weapons. An early Selenoclont (crescentic-toothed)
animal of this kind for the primeval pair-hoofed
group — one which, like the Hyopotamus, does not
belong distinctly to any special type — is the genus
Cainotherium, an animal of the most graceful shape ;
we have probably a correct picture of its appear-
ance in the living dwarf musk-animals (Fig. 30).
That Cainotherium and its relatives, e.g. Xiplio-
don, Xiphodontherium, were Euminants, cannot be
doubted from the position and nature of the
tranverse ridges of their molars, also from the
character of the joints of the jaw upon which
depends the peculiar action of the grinders. The

dental formula is i -, c-, p -, ra -, and in most

o 1 4 o

specimens they stand in closed rows in both jaws.
Now our present hollow-horned animals have no
incisors in the upper jaw, and no canines either in
the upper or lower jaw, and, moreover, they occur
in the upper jaw only in some species of deer. The
diminution of the teeth — a very general pheno-
menon— must, therefore, have taken place gradu-
ally in the course of ages. How and when this
occurred, Filhol ' has very clearly pointed out with

1 Compare p. 64, note 2.

THE ANTELOPES AND OXEN.

183

respect to the above-mentioned animals. The
Cainotheria, to judge from the quantities of their
remains, must have lived in herds after the
manner of the Antelopes ; hence hundreds of skulls
and thousands of lower jaws could be compared.
Further, an extraordinary variability was found

FIG. 30. — Skull of Cainotherinm metopias. Nat. size (after

Filhol).

in the canine tooth (Fig. 30, c), and in the front
premolars. The normal row of teeth, i.e. the teeth
inherited from early times, begins to show gaps ;
a small gap occurs between the canine and the
first prernolar ; the latter then moves towards the
canine ; frequently the second premolar follows ;
both thus obviously become useless, and the next

184 THE MAMMALIA.

stage is their total disappearance. Further, we
then see indications of the brow weapons, in
correlation with the loss of the canines. Filhol
here reminds us of the proposition expressed
even by Aristotle, and formulated again at the
beginning of this century by Etienne Geoffrey St.
Hilaire with regard to the balancing of the organs
(balancement des organes). With the loss of the
front premolars, the permanent molars become
more regularly developed, and it is thus that the
now typical ruminant jaw has been farther and
farther developed ; the ancient form — owing to
complete rows of teeth and the more marked
canines— still, in some measure, resembled the
jaw of the Omnivora and the Bunodonts (animal
with tuberculate teeth).

From Filhol' s observations we find that this
process of the gradual formation and the fixing of
the gap in the dentition of the Euminaiits has
repeated itself — that, at first, individual modifica-
tions became established by inheritance, and led
to the formation of races. And although we
cannot, in every instance, trace the given advan-
tages connected with the modifications, and that
led to the selection, still, as was shown above, we
have some idea, as well as some explanation, of

THE ANTELOPES AND OXEN. 185

the advantages, and they account for the gradual
disappearance of the primary groups and for the
origin of new species.

In America we find the same circumstances.
Antelopes and oxen have, it is true, decreased in
a remarkable manner among the present American
fauna, but the abundance of the fossil forms is so
great that we can scarcely find fault with the
patriotism of the American naturalists, when we
find them, in this case also, claiming their country
to have been the cradle of this group of Hoofed
animals. Of purely American types we will name
only the very numerous family of the Oreodonta,
which combines traits of the pig-shaped pair-
hoofed, or thick-skinned animals, i.e. the large
canines as weapons, and molars of the ruminant
type. They were so numerous in the Middle Eocene
that one stratum has been called after them, and,
together with this force of numbers, they show
' that tendency to differentiate into races and
species which seems to be characteristic of pri-
mary forms.

Although America was rich in the still indefinite
precursors of our present Kurninants, it has re-
mained absolutely unproductive as regards Oxen.
For even the Diluvial ancestor of the North Ameri-

186 THE MAMMALIA.

t

can bison might be disputed as belonging to America.
This naturally touches upon extremely important
points in anthropology and the history of civilisa-
tion, particularly in connection with the other cir-
cumstance that the line of horses was broken off
precisely at the point where the American Man first
appeared on the scene ; and moreover when he was
still in so rude and helpless a state that he could
not have brought either one or the other of his
fellow- workers with him from his Asiatic home, to
aid him in his further advance in civilisation.
Hence the same phenomenon, as was shown above
to have occurred in Australia, has been repeated
here, even though in a less striking manner. Even
at the beginning of our century, buffaloes (Bison
americanus) crossing the prairies were to be counted
by hundreds of thousands. Nothing points to the
fact that the American aborigines ever made any
attempt to tame these wild creatures. It would
seem rather that throughout the whole of North
America the Indian was, in a manner, chained to
the buffalo, and that from year to year he had to
pass from one pasture to another with the animal.
Hence it was impossible that the higher civilisation
of a settled life could take the place of a huntsman's
career. Only those tribes which wandered from

THE ANTELOPES AND OXEN. 187

the north southwards, to central and to one part of
South America, could attain any comparatively high
development of civil life ; and this was owing to the
more favourable climatic circumstances, and to
various species of llamas having been made use of
as domestic animals.

The introduction of oxen and of horses from
Europe was the beginning of the end of the Ameri-
can bison. The bison has found its biographer in
Professor Allen,1 who has clearly pointed out its
relation to the Diluvial races ; and as regards this
relation Allen arrives at a somewhat different con-
clusion to what Biitimeyer2 does. The earliest form
is the gigantic Bison latifrons from the Diluvial strata
of North America, where also are found the remains
of mastodon, megalonyx, mylodon, and others. It
produced species (races?) not very different from
one another, the Bison antiquus of the New World,
and the B. pnscus of the Old World. The latter
is the progenitor of the Europe-Asiatic urus or
wild bull ; the Bison antiquus, which lived contem-
poraneously with the Elephas primigenius, is the
progenitor of the Bison americanus.

It is very probable, as already remarked, that

1 Allen, The American Bison. Cambridge, Mass., 1876,

2 See above, p. 178.

188 THE MAMMALIA.

the original inhabitants of America did not make
any attempts to tame the buffalo. At all events,
they did not succeed in doing so. Very different
have been the results of the attempts of the Euro-
pean immigrants, who have repeatedly been engaged
in this task since the middle of last century. They
have succeeded pretty easily in obtaining a cross
between the wild and the domestic animal, by
allowing the captured young ones to grow up in the
herd ; and it seems certain that this will produce
a strong cross-breed. A Mr. Thompson, who, ac-
cording to Allen, had watched the attempts at
domestication of the unmixed species during fifty
years, has expressed his conviction that the animal
is capable of being employed for work as well as
for yielding milk, while the earlier attempts at cross-
breeding were made principally with a view to the
horns and skins of the animals.

Under these circumstances, it seems natural that
the question should arise as to whether one or the
other race of the European ox must not be traced
back to the bison. All those who have carefully
studied the question declare the bison to be unfit
for domestication, and have referred all the different
races of the domestic ox — with the exception of
the yak — to the genus Bos distinguished by the

THE ODD-HOOFED ANIMALS. 189

characteristic formation of the forehead. Wilckens
alone1 has drawn attention to the resemblance
between the skull of the short-headed cattle of
Eastern Tyrol (Dux) and that of the bison, and
thinks that further investigations would furnish a
complete proof for this derivation.

Peris sodactyla, or Odd-hoofed Animals.

The Odd-hoofed animals are at present repre-
sented by three groups : Tapir, Khinoceros, and.
Horse, all of which are poor in species. The re-
duction in the fore and hind- foot has advanced
farthest in the horse ; the middle toe, owing to the
complete disappearance of the others, has become
the sole support for the weight of the body. There
exist only the mere rudiments of the metatarsals
of the second and fourth toe. The tapir comes
first with four toes on the fore-foot, and three on
the hind-foot; the rhinoceros has three toes on
both the fore and the hind limbs, and both these
groups have preserved very ancient characteristic
features. But in spite of its transformation having
advanced so far, no other mammal of the present

1 Wilckens, ' Ueber die Schadelknochen des Eindes aus den
Pfahlbauten des Laibacher Moores, 1877 ' (Communications to
the Anthropological Society of Vienna).
18

190

THE MAMMALIA.

day can show as distinct or regular a pedigree as
the horse. By means of the accompanying table
we will endeavour to solve our problem. The con-
nections are, upon the whole, so simple and clear
that, although palseontologists may differ in the
explanation of the relationships, these differences
refer merely to subordinate points.

TABLE SHOWING THE CONNECTION BETWEEN THE ODD-HOOFED ANIMALS.

Rhinoceros Horse

Elasmotherium Pliohippus '

Hipparion Protohippus

Present Time Tapir
Diluvium

Miocene

Eocene

Tapir

Lophiodon

Rhinoceros
Aceratherium

Anchitherium Miohippus

Mesohippus

Palasotherium med. Orohippus
Palseotherium Eohippus

Palasotheridse (four and three toed)

Anti-Eocene odd-hoofed animals
1 American line of horses.

1. TAPIR AND RHINOCEROS.

Of Tapirs we have two or perhaps three species
in South America, and one in India. Their
favourite haunts are moist forests. Their dentition
is very complete in spite of a considerable gap
between the canines and molars. The dental for-

.3 1 4.3
mula is : i -, c -, m -_.
o 1 o . o

THE TAPIE AND RHINOCEROS.

191

The incisors and canine teeth are, as usual, not
of any special form or construction, whereas the
cheek-teeth show a very peculiar type by the
marked character of two transverse ridges, the tops
of which, both inside and outside, become tolerably
sharp tubercles (Fig. 32). The ridges of the upper
teeth are situated on the front and in the middle

FIG. 31.— Skull of the Tapir (Tapirus americanus).
n, Nasal bone ; t, bony wall separating the nasal cavities.

of the crown ; they fit into the grooves of the lower
molars, where the back ridge rises from the back
wall of the tooth. The grinding movement peculiar
to the Euminants can be accomplished by the tapirs
only in a very slight measure ; on the other hand,
their teeth are specially adapted for crushing vege-
table substances, which can also be roughly cut by

192 THE MAMMALIA.

the sharp ridges of the crowns of their teeth.
Although the fore-foot of the tapir possesses four
perfect toes, still, from an examination of the
skeleton of the foot, it hecomes evident at once that
the second toe from the inner side, corresponding
with the middle toe of the five-toed limb, is more
strongly developed than the rest, and that it stands
in that peculiar position which we have shown to

CD

FIG. 32.— Back Molar of the Lophioclon parisiensis, on the left

from below.
A, a, Front and back outer tubercle ; /, i, front and back inner tubercle.

he the distinguishing feature in the Odd-hoofed
animals. A five- toed genus with the middle toe in
this position has, as we have seen, been preserved
in the Coryphodon from the Eocene formation.
Now, as the lowest known tapir-shaped animals
possess at most four toes, the unknown primary
forms must, of course, be looked for in the secon-
dary divisions. The tapir, in addition to having
lost the inner toe, has also lost the fifth toe ; this

THE TAPIR AND RHINOCEROS. 193

is another instance of the law laid down on p. 169,
that the hind extremities are more readily and
more frequently reduced than the fore limbs.

In the tapir we have an animal from the Early
Tertiary period that has remained almost wholly
unchanged, one of those species which have been
called permanent, and which are more frequently
met with in the lower animal world. They do not
prove the invariability of the species, but prove
only that under certain circumstances the stability
of the species can be of an extremely long duration.
In the Miocene the genus is represented by several
good species. In the Middle Eocene, we have in its
place the Lophiodon, which is characterised by a
still greater simplicity of the ridges of the teeth,
and, as regards appearance generally, may have
been scarcely distinguishable from the tapir. The
European Lophiodonts naturally, in the first place,
lead over to the Indian caparisoned tapir. The
American ancestral line of the tapirs is more com-
plete. Two genera, Helaletes and Hyrachyus,
closely related to Lophiodon, belong to the Eocene.
They may be called tapiroid forms. At a somewhat
later period appears Lophiodon, one of the few
genera we have in common. Still more tapiroid
in form is the Miocene Tapiravus, which in the

194 THE MAMMALIA.

Post Tertiary is followed by the tapir itself. That
the animal migrated to its present home in South
America is probably certain. Now Eocene races
existed in the Eastern as well as in the Western
Hemisphere, whose origin and separation is in-
deed unknown, but the form and character of
the feet and teeth would require but small
changes to produce the genus Tapir. Hence it is
here again merely a matter of opinion (owing to
the present state of our knowledge) whether, with
Marsh, we consider it more likely that the original
home of the tapirs is assigned to the New World,
and that they are supposed to have migrated to
Asia, or vice versa ; or again, if, with Carl Vogt, a
parallel development is considered the more prob-
able hypothesis.

By the side of our present tapirs, and unmistak-
ably allied to them in the formation of foot and
dentition, stand the Rhinoceroses, which are dis-
tributed over Southern Asia, with its large islands,
and Africa. The head weapons are solid horny
projections of the nasal bone, which rise into a
fiat hump within equalities of the bone substance.
From this characteristic feature it can in most
cases be determined whether the fossil animals of
the Khinoceros species possessed horns.

THE TAPIK AND EHINOCEHOS. 195

Throughout the whole of the Diluvium and the
Tertiary period up to the Palaeotheriae and Lio-
phodons, there existed rhinoceroses, or hornless
animals closely related to them. Midway in the line
stands the hornless Aceratherium. Its connection
with the Palaeotheridae and the Tapiridae becomes
at once apparent from an examination of the skull ;
still, a diminution of the front and canine teeth
has taken place. In fact, the whole family of the
Rhinoceridse, up to the present day, shows more
variability of the incisors and canines than any
other group. The dental formula of the Acerathe-

2*0*7

rium is ' — . Also by possessing four toes on

the fore-limbs it stood closest to its five-toed an-
cestors. Aceratherium is followed upwards by the
true rhinoceros with enlarged nasal bones capable
of supporting heavy horns. In several of the
Diluvial species — above all, in Rhinoceros ticho-
rhinus,1 which ranged across Central Europe as far
as the Asiatic Polar Ocean — the otherwise gristly

1 A rhinoceros, with a bony partition between the nostrils,
lived in Europe with the mammoth up to the period of Man, and
its fossil remains, like those of its contemporary, helped our fore-
fathers in their conception of giants and dragons. On the market
place in Klagenfurt is a very old stone image of a dragon, the
head of which has most unmistakably been modelled from the
skull of Rhinoceros tichorhinus.

196 THE MAMMALIA.

partition between the nostrils became a firm bony
support for the horn, an ossification, which is not
unfrequently met with in the tapir, as was shown
on Fig. 31.

America, too, had its family of Ehinoceroses,
which seem to have branched off from the Middle
Eocene Tapiridae, and comes forward distinctly in
the Upper Miocene as Aceratherium. Forms similar
to it are found in the Pliocene, but did not leave
any descendants to the following period. The
causes of its extinction in the New World are not
clear. But the reason of the dying out of the
Diluvial species in the Old World, or its withdrawal
from the temperate zones to tropical regions, seems
to be pretty obvious. For even though individual
forms — such as the rhinoceros with the bony par-
tition between the nostrils — were, like the mam-
moth, able to endure a rougher climate, still they
were not able to face the coming of the Glacial
period. What prevented them withdrawing before
it we certainly do not know ; still we may, at all
events, look upon them as having been the victims
of climatic changes. Others, which were able to
avail themselves of the land bridges for with-
drawing southwards, survived.

An animal of the rhinoceros type, which was

THE TAPIR AND KHINOCEROS.

197

perhaps a contemporary of Man, and one of the
most gigantic phenomena of the primeval world, is
the Elasmotherium. It likewise possessed a bony
partition between the nostrils, and was armed with
an immense horn, as is proved by the rough and
huge elevation on its forehead. Its skull is over
three feet in length. The form of the molars, with
elaborately folded plates of enamel, is another

FIG. 33. — Skull of the Elasmotherium. One-twelfth nat. size.

After Brandt.

peculiarity. This giant of the Diluvial period was
also unable to preserve its existence. The few
remains — among which is an almost complete
skull — have scarcely been found anywhere except
in the southern basin of the Volga.

The size of the present animals of the Khinoceros
species, and of most of the primary species, will
seem less striking if we take into consideration the

198 THE MAMMALIA.

smaller species of bygone days, for instance, the
Rhinoceros minutus.

Before passing on to the most docile and
important group of the Odd-hoofed animals, the
horses, let us first turn our attention to a few of
the American forms, which are distinguished partly
by their size and partly by the, in most cases, very
unusual form of their skull ; in the struggle for exist-
ence these animals, however, neither changed nor
left descendants which adapted themselves to cir-
cumstances. Their existence reminds us of the
Elasmotherium, inasmuch as they neither explain
the present (hence in reality stand apart from our
subject here), nor do they awaken in us other ideas
for understanding the organic world ; but they
bear witness to the incredible exuberance, we may
almost say the capriciousness, of organic produc-
tivity during the Late Tertiary and Diluvial periods
while the animals were becoming extinct, and
which periods were followed by our Present age,
with a certain stability of the inorganic and
organic worlds. In this stability of forms, moreover,
we see one of the preliminary conditions of the
morphological and social development of mankind.

The lowest strata to the east of the Eocky
Mountains contain the remains of the Brontotherida,

THE TAPIR AND RHINOCEROS.

199

gigantic animals, whose bodies exceeded that of the
elephant in bulk, but they had shorter limbs with t

FIG. 34.

A. Skull of Brontotherium ingens. One-tenth nat. size, n, Nasal bone ;

i, mid jawbone ; m, upper jaw ; j, cheek bone ; /, frontal bone ;
p, parietal bone ; c, condyle.

B. The same looked at from above, with the brain given in outline. After

Marsh.

four toes on the front feet and three behind. The
skull (Fig. 34), which is elongated after the manner

200 THE MAMMALIA.

of the Rhinoceros species, shows a pair of bony
protuberances (the supports for mighty horns) on
the upper jaw, in front of the eye-cavities, and prob-
ably the nasal bones and the intermediate space
between the horns permitted the addition of a
proboscis.

Both in the case of Brontotherium as well as
in some members of the family of the gigantic
Dinocerata, to be spoken of presently, the relative
size of the brain to the skull is known from fossil
impressions. According to these the size of the
actual brain substance must have been extremely
small (Fig. 34, B.). Its extent reminds one of the
relative proportions of the reptile brain, and points
to an incongruity which must certainly have had
its effect upon the dying out of this and of similar
species. It was in this manner that all the huge
reptiles of the middle geological periods became
extinct, especially as land animals. The few huge
but small-brained reptiles of the present day, such as
the crocodiles, clearly owe their existence to the fact
that they have continued to live in water, also to
their marked stability. A transition to life on land
would lead to their extinction.

From the circumstance that one of the more
recent strata of Oregon contains the remains of a

THE EQUID^E, OH HORSES. 201

perhaps kindred genus, the Chalicotherium — which
is discovered also in Western America, in China,
India, Greece, Germany, and France — Marsh con-
cludes that the places where these remains were
found were the stages by which, in this and other
cases, the so-called * Old World ' received its animal
forms.

2. THE EQUIDJE, OR HORSES.

On Fig. 35 we have a drawing, made by Owen in
1857, to explain to his audience the derivation of the
one-hoofed animal from its three-hoofed ancestor, a
drawing which has been made use of countless times
since then by recent writers. The three-hoofed
animal is the Palceotherium medius discovered by
Cuvier ; in outward appearance the foot is precisely
like that of the tapir, but possesses four toes on
its fore-foot, and thus represents an earlier form.
The Palaeotheridae are essentially Eocene ; to judge
from their teeth, they obtained their food like the
tapirs, and (with a numerous kindred) inhabited
the marshy forests which had originated with the
upheaval of the weird depths of the Jura and Chalk
oceans. They, too, had found their way to
Southern America. It is, we know, perfectly use-
less, at the present state of our geological know-
ledge, to endeavour to determine by means of
19

202

THE MAMMALIA.

which land-bridges this migration took place ; all
that can be done meanwhile, is to trace the line
of the descendants of the Palseotheridae, which, it
seems, soon came to an end in South America, but
became very numerously and continuously de-
«M

jr MIV

VT77

FIG. 35. — Palaeotherium. Hipparion. Horse (after Owen).
p, First premolar ; m, first molar.

veloped in North America ; and in tracing this line
we must do so independently of those branches
which run parallel with them in Europe and Asia.
Palaeotherium is a distinctly three-hoofed animal.
Certainly the middle toe is somewhat larger than

THE EQUIM:, OK HORSES. 203

the two side toes, which, although shortened a
little, and accordingly somewhat more perpen-
dicular, yet fully touch the ground, and take
their share in the work as bearers of the weight
of the body. Now in the genera which gradually
arose in the course of time — Palaotherium, Anchi-
tlieriuiiiy Hippo/lion, and Horse — we can trace how
the two side toes, n and iv, were more and more
withdrawn from the ground, and became rudi-
mentary, whereas the middle toe increased in size,
stretched out, and finally became that of the Horse,
the incomparable runner and fellow- worker of man.
Owen looks upon this as a providential transforma-
tion designed for the benefit of mankind ; we look
upon it as an adaptation to the formation of the
ground, to the incoming of plains, which originated
during the Tertiary period. Thus in Anchiiherium
aurelianense (Fig. 36), which is still met with even in
the Eocene, the tips of the outer toes are scarcely
withdrawn from the ground, hence might still have
been of use to the animal in walking through a less
firm soil.

The Hipparion also, from the Middle Tertiary,
possesses the lateral toes (Fig. 35), but these are only
rudiments of the original toes. They have become
wholly useless, and in accordance with this inaction

204

THE MAMMALIA.

the bones of the middle foot
have also become shortened, and
are on the way of becoming
rudimentary. In Hipparion the
adaptation of an animal once
accustomed to marshy ground,
to one which lived on firmer
ground with extensive meadow
lands has become completed;
we have, in fact, the transforma-
tion from a slowly-moving into
a swift animal. It ranged from
Central Europe as far as Central
Asia, and in both countries lived
in enormous herds, as we learn
from Gaudry's graphic picture of
the Miocene uplands of Pikermi.
The transition from Hip-
parion to the Horse is a very
natural one. The two side toes
— which are no longer of use to
the organism, and
yet had to be

Fio. 36.- Left hind-foot
of the Anchitherium.
One-half nat. size.
After Kowalewsky.

THE EQUID.E, OR HOUSES. 205

nourished — have been eliminated as ballast. They
are not yet quite cast off. The metatarsals, or
so-called ' splint bones,' are still attached to the
middle toe. The horse of the future will certainly
have cast off these rudiments, even though it may
take a few millions of years to accomplish this,
owing to the extraordinary perseverance with which
organisms drag about with them these useless in-
heritances. The Hipparion has not even yet
wholly disappeared from the scenes of life.

Now and again horses have been met with, with
more than one toe, which must not rashly be
considered as a malformation ; it is simply a proof
of that repetition of or reversion to the original form
which in scientific language is called atavism.
This kind of Hipparion-horse, which is looked upon
by the common run of people as a curiosity and
monstrosity, has, as Siebold1 has shown, been
repeatedly exhibited at horse-markets. The fol-
lowing is a description of an animal of this kind
given by Frank, Principal of the Veterinary College
of Surgery at Munich : ' The so-called splint bones
(the metacarpals and metatarsals of the second
and fifth toes) are not reduced to the same extent.
On the fore-foot the mediale (M c 2) is the least

1 Siebold, Hipparion auf Jahrmarkten. Miinchen, 1881.

206 THE MAMMALIA.

reduced, on the hind- foot the lateral (M c 4) is the
least reduced, as even Hensel pointed out. Now
cases of atavism are not unfrequently met with in
the horse, where the medial splint hone on the
fore- foot has a digit more or less distinctly de-
veloped. And as the hoof of this second digit never
touches the ground, and, accordingly, is not worn
off in any way, the horn- substance becomes long
and irregular, precisely as in the case of the lateral
toes (the second and fifth) in old cows. Atavisms
of this kind on the hind- foot are of extremely rare
occurrence.

' When it was said above that the horse no longer
shows any trace of rudimentary toes, this is not
altogether correct ; the rudimentary hoofs do still
exist. Thus the so-called " chestnut," a flat horny
wart on the skin above the carpus, seems to corre-
spond to the hoof of the lost thumb ; at all
events, I found it in cases where a second digit
existed. Another formation that must be included
here, is the so-called " spur." This spur is a small
cylindrical horny substance, which in our present
horse is concealed by the hairy tufts of the fetlock.
It seems to represent the coalesced horn- shoe of
the rudimentary second and fourth toe of the
horse.

THE EQUID^E, OR HORSES. 207

k During the sixth decade of the present century,
there was exhibited in Munich a horse under the
name of a " stag-horse," which had veritable hip-
par ion feet. The splint bones of the four extrem-
ities had digits, that is, toes. The so-called
" chestnuts " existed on all the four limbs, and were
strongly developed, whereas all the four " spurs '
were wholly wanting.1 On the fore-feet the medial
side-hoof (second digit) was most fully developed,
on the hind-feet it was the lateral or fourth toe. As
the side-hoofs of all the extremities did not reach
the ground, and hence were not worn, they had
grown to a considerable length, and were bent like
horns. Such cases are of great rarity ; still they
had been observed even in earlier times. The
famous Bucephalus of Alexander the Great is said
to have been an animal of this kind. Moreover,
the atavism is said in some instances to have been
transmitted to the offspring, which of course is very
probable. It is more than probable that from a
single animal of this description a breed of Hip-
parion-horses might be reared. There would,

1 This observation would certainly support the opinion, which
we are inclined to doubt, that the ' chestnuts ' and ' spurs ' were
rudiments of the first, second, and fifth hoofs. If, nevertheless,
I hold to my doubt, at all events as regards the atavism of the
thumb, I do so because it would be a unique phenomenon.

208 THE MAMMALIA.

however, be absolutely nothing to be gained by
such reactionary measures.'

The same indications of the transformation
from Palseotherium to our present Horse — in an
uninterrupted line from the Eocene to the present
— are manifested by the teeth. In connection
with this point we must first of all mention
Riitimeyer's classic studies on this question,1 which
have been admirably supplemented by Forsyth-
Major. Owen had already recognised the change
in the formation of the jaw that accompanied the
transformation of the organs of locomotion. The
teeth of the Pal&otheridae, which show less com-
plicated folds of enamel, and are adapted for
crushing juicy plants, gradually change into the
pillar-shaped molars of the horse, which, owing to
their strength and the foldings of enamel, are
suitable both for grinding corn and for chopping
gritty grasses. The principal parts of the crowns
are given on the accompanying drawing (Fig. 37).
Even from Owen's illustration it is evident how the
complicated enamel lines of the horse's tooth
originated from the simple tracings on the tooth
of the Eocene animal. The much more careful

1 Kiitimeyer, Bcitrage zur Kcnntniss tier fossilen Pferde,
1863.

THE EQUID^E, OR HORSES.

209

comparisons of recent times have shown us these
changes down to the minutest detail ; and from the
geological series, which is being made more com-
plete year by year, the complex formation of the
horse's molars becomes perfectly intelligible from
the outlines on those of the Palaeothermm. Kiiti-

FIG. 37. — Right Upper- jaw Molar of the Horse.

a, t, r, h. Outside, inside, front, back ; M, m, front, back crescent ; P, p, larger
and smaller inner pillar ; F,f, inner main- and side-fold. After Branco.

meyer further gives special proofs that the species
in question transmitted the relative peculiarities of
their molars to the milk-teeth of their offspring
and descendants, whereas the descendants trans-
mitted the new inheritance specially to the molar
teeth.

210 THE MAMMALIA.

It is only in its historical connection that the
peculiarity of the horse's dentition acquires a
peculiarly significant interest, and — as in the case
of the three- toed foot — when viewed apart from the
historical course of its development, seems simply
an incomprehensible peculiarity, of no importance
either to the horse itself or to the horse fancier,
Palaeotherium, Anchitherium, and Hipparion pos-
sess, when full grown, seven cheek-teeth above and

4 3

below on both sides of the jaw, p -, m - . On the

other hand the normal formula in the horse's den-
tition is p -, m ; it changes only three of its
o o

milk-teeth, and gets three other molars. Now it
has long since been known to breeders and veterinary
surgeons that, pretty frequently, the horse's row
of cheek-teeth begins with one stump too many,
the so-called ' wolfs tooth ' (on Owen's drawing
marked by the letter p). This most perfectly ex-
presses the fact that it occupies the place where,
in Palaeotherium among others, we have the first
premolar. When it appears in the horse, however,
the ' wolf's-tooth ' is not deciduous. It is most
obviously a tooth in the last stage of disappear-
ance, an irregularly appearing descendant from the

THE EQUID^E, OR HORSES. 211

days of a full dentition, and its disappearance
probably stands in causal connection with the
increased strength of the other teeth.

Before discussing the American line of horses,
let me here quote W. Kowalewsky's opinion regard-
ing the connection between the genera mentioned
above ; his remarks are as careful as they are con-
vincing: * Nothing is further from my intention
than to maintain that the animal which we call
Pal&otlierium medium directly produced an Anchi-
theriurn, the latter an Hipparion, and so on. But
among the number of individuals which we call
Palseotheridge, there must always have been some
forms which would incline more towards the Anchi-
therium than the others. In the same way I have
been able to determine — owing to the large number
of species I was fortunate enough to be able to com-
pare— that among the Anchitherida3 a few still
remained completely within the limits of the species,
although they showed some characteristics by which
they resembled the Horse on the one hand, and the
Palaeotherium on the other. A few trifling flattenings
of the bones, certain peculiarities of a joint which
are met with in some individuals, are not to be found
in others. Without doubt there was at one time a
transition between two individuals which resembled

212 THE MAMMALIA.

each other most; but to expect, as is generally
asked by those who believe in the invariability of
species, that we should be able to show the last
Palaeotherium, and his descendant the first Anchi-
therium, is to demand an impossibility. An origin-
ally normal characteristic sometimes begins not to
occur, then it becomes unimportant, i.e. is found
wanting as often as it occurs, then it appears rarely,
and finally disappears completely. Thus, for in-
stance, the small front premolar of Palseotherium
is smaller still in Anchitherium, but still occurs
regularly ; in the Hipparion it is met with as often
as it is found missing, and in our present Horses
it is extremely rare (as the "wolf's tooth").' This
very careful comparison of the differences in the
dentition has been further worked out by Kowa-
lewsky.1

We have now again to turn to America, to the
well-known fields of discovery to the right and left
of the Eocky Mountains, where to all appearances
a group of Odd-hoofed animals lies buried, much
more numerous in members than the group in the
Old World, showing no gaps, and terminating with
the horse. Compare the table on page 190. The

1 W. Kowalewsky, ' Sur 1'Ancliitherium Aurelianense Cuv.,'
Mtm. de I' Academic imp. de St. Pelersbourg, 1873.

THE EQUID^E, OR HORSES.

213

line begins in the Early Eocene with, the Eoliippus
of the size of a fox, which possessed, in addition to
the four well-developed toes of the fore-foot, the
remnants of a fifth. According to a remark of
Marsh's, this animal, in foot and dentition, al-
ready shows unmistakably that with it commenced
the branching off of the progenitors of the horse

d

rA

nr m

FIG. 38.— Foot of the Fossil Horses of North America.
a, Orohippus ; 6, Mesohippus ; c, Miohippus ; d, Protohippus ; e, Equus.

from the other Odd-hoofed animals : * in the next
higher division of the Eocene, another genus
(Orohippus, Fig. 38) makes its appearance, replacing
Eoliippus , and showing a greater though still dis-
tant resemblance to the equine type. The rudi-
mentary first digit of the fore-foot has disappeared,

and the last premolar has gone over to the molar
20

214 TUE MAMMALIA.

series. Orohippus was but little larger than
Eohippus, and in most other respects very similar.

* Near the base of the Miocene we find a third
closely allied genus (Mesohippus), which is about as
large as a sheep and one stage nearer the horse.
There are only three toes and a rudimentary splint
bone on the fore-feet and three toes behind. Two
of the premolar teeth are quite like molars. The
ulna is no longer distinct, or the fibula either, and
other characters show clearly that the transition is
advancing. In the Upper Miocene Mesohippus is
not found, but in its place a fourth form (Mio-
hippus) continues the line. The genus stands
close to the Anchitherium of Europe, but presents
several important differences. The three toes in
each foot are more nearly of a size, and a rudi-
ment of the fifth metacarpal bone (of the second
series) is retained. All the known species of this
genus are larger than those of Mesohippus, and
none pass above the Miocene.

* The genus Protohippus of the Lower Pliocene is
still more equine, and some of its species equalled
the ass in size. There are still three toes on each
foot, but only the middle one, corresponding to the
single toe of the horse, comes to the ground. This
genus resembles most nearly the Hipparion of

THE EQUIPS, OR HORSES. 215

Europe. In the Pliocene we have the last stage of
the series before reaching the horse, in the genus
Pliohippus, which has lost the small hooflets and
in other respects is very equine. Only in the
Upper Pliocene does the true Equus appear and
completes the genealogy of the horse, which in the
Post-Tertiary roamed over the whole of North and
South America, and soon after became extinct.
This occurred long before the discovery of the
continent by Europeans, and no satisfactory reason
for its extinction has yet been given.' 1

So far Marsh, and, owing to the quantity of his
discoveries, he proclaims the horse, above all the
other hoofed animals, to be clearly a native of
America. That the European line discussed above
is more incomplete is very evident ; however, it must
be assumed that with further discoveries the differ-
ence will be equalised. And, indeed, an important
beginning has already been made during the last
few years. The gap between Hipparion and Equus,
which clearly existed, and was filled up in the Ame-
rican line by Pliohippus, no longer exists in the Euro-
pean series either. For Forsyth-Major 2 has pointed

1 Marsh, The Introduction and Succession of Vertebrate Life
in America (1877).

2 Forsyth-Major, ' Rivista scientifica industrials, 1876,'
Kosmos, ii.

216 THE MAMMALIA.

out that the races from the Quaternary period of
Upper Italy, classed together as Equus stenonis,
include all the required intermediate stages between
Hipparion and our present Equus caballus. It is
of the utmost interest to be able to prove that in
Equus stenonis the reduction of the side meta-
tarsals preceded that of the tarsals : for while the
metatarsals do not differ from those of our present
horse, the tarsals show all the intermediate stages
between Hipparion and Equus caballus ; they have
not yet had a sufficient length of time to accom-
plish the complete change which renders the foot
of our horse so eminently more suited to the
activity of the one-hoofed animal than was the
Equus stenonis. In fact, it may be affirmed that
in the case of the Diluvial horses, the splint bone
(i.e. the rudiments of the metatarsals n and iv)
had not yet coalesced with the mid-foot, which
coalescing of the bones occurs in our present horse
with its seventh or eighth year.1

1 Nehring remarks, on the other hand, that in our present
horse, the splint bones do not coalesce nearly as often as is sup-
posed, and that, for instance, among the skeletons in the Berlin
collection, the coalescing is the exception, the non-coalescing the
rule. That, therefore, the supposed difference between the Dilu-
vial and the present horse is not an essential one, and that it
need only be admitted that the coalescing of the splint bones
occurs more frequently in the domestic horses of the present

THE EQUIM:, OR HORSES. 217

That the two groups, the European and the
American, run parallel, perhaps without any inter-
course during the longest of the Mid-tertiary
periods, must not only be admitted as probable,
but be granted as possible. The probable coloni-
sation of America by the original inhabitants of
Asia took place before they had learned to make
use of the horse as a domestic animal. In
America the Horse no longer existed then. It
may be that the long-continued ice-formations
of the Diluvium had forced it to leave the high-
lying plains to which it had been accustomed,
and driven it to regions where it succumbed in
the struggle for existence. The Spaniards re-
introduced the horse to the New World, and now it
there also fulfils its mission as a companion to
man — if we may for once use a teleological ex-
pression. In addition to all this, however, it must
also be stated that the American members of the
genus Horse have never advanced as close to our
present horse as the Diluvial members of the Euro-
pean family ; hence, that the true horse of our

than in the Diluvial horses. Now, as Nehring, among other
things, proves that the splint bones of the Diluvial horse, of
Westeregel, are considerably larger and longer than they are
usually found in the domestic horse, the circumstances we en-
deavoured to prove above remain essentially the same.

218 THE MAMMALIA.

day — Eqiius caballus — never existed in America
before its importation. Branco l has lately pub-
lished a very remarkable treatise on this subject.
He has shown that in the Equus anclium — which
lies buried in the volcanic tufa of Ecuador, and is
of the same age as the Diluvial Pampas horses and
the species found in the caves of Brazil — the eye
is placed considerably deeper, whereas in the Equus
caballus it has moved considerably farther back.
Here, again, it is our grand Goethe — a naturalist
not nearly often enough quoted, in spite of what
an eminent Berlin orator may say — who sixty
years ago pointed out this ideal character of the
horse from an artistico-scientific point of view, and
thus anticipated the wearisome labours of palseon-
tology. Goethe's words are2 : ' In the horse's head
of the Elgin Marbles (of the Parthenon), one of the
most splendid relics of the grandest period in art,
the eyes stand out freely and are placed near the
ears, whereby both senses, sight and hearing, seem
to act together directly, and the sublime creature
is enabled to hear as well as to see what is happen-
ing behind it. It looks so majostic and spirit uel,

1 Branco, Die fossile Saugethier fauna von Punin und Ecua-
dor, von Reiss und Branco. Berlin, 1883.

2 Goethe, Ueber die Anforderungen an naturhistorische
Zeichnungen (1823).

THE EQUID.E, OK HORSES. 219

almost as if it had been formed contrary to nature,
and yet the artist has, in reality, given us a pri-
meval horse, whether he saw it with his own eyes
or conceived it in his mind ; to us, at all events,
the animal seems depicted in the spirit of the
highest form of poetry and reality.'

The horse, in all its various forms of develop-
ment, from the dwarfish pony to the Percheron
and the huge English cart horse, has been regarded
as a single species ever since it was found in the
service of man. We talk only of different races
of Equus caballus. The taming and breeding of
horses may be said certainly not to have taken
place for thousands of years after the time when
man first came into contact with the animal. The
period during which prehistoric Man, in Europe,
fed chiefly upon horse flesh is that which has also
been called the Reindeer period, owing to the wide
distribution of that animal. This division of time
follows the period of the fullest development of the
mammoth, and was in many localities — e.g. in
Central France — extremely favourable for the in-
crease of the genus Horse, in spite of an evidently
rough climate. Nowhere in the world are such
accumulations of remains found as near Solutre in
the neighbourhood of Macon to the north of Lyons.

220 THE MAMMALIA.

The lower stratum of this remarkable deposit con-
tains a whole fauna of larger and smaller mam-
mals— mammoth, cave tiger, lynx, cave bear, brown
bear, cave hyena, wolf, fox, polecat, marten, bad-
ger, Canadian deer, primeval ox, horse, hare, and
saiga-antelope. All the bones are broken and
mixed up together ; and the rude flint implements
likewise found there, also point to the fact that the
grass-eaters fell victims not only to the teeth of the
beasts of prey, but to the hand of huntsmen as
well. In the upper strata the mammoth and his
huge flesh-eating contemporaries disappear from
the scenes. Primeval Man entered the Eeindeer
period from the Mammoth period, and thereupon
horses were slain by the thousand.

The opinion which found favour in France that
the horse of Solutre had been tamed and domes-
ticated is untenable, as has again lately been
pointed out by Pietrement, who has carefully con-
sidered the question in all its bearings.1 Never-
theless, the horse from Solutre is of great interest,
as we most probably have in it one of the races
which subsequently became domesticated, and which
left descendants that probably still exist. The pieces

1 Pietrement, Les chevaux dans les temps prchistoriques et
Mstoriques. Paris, 1883.

THE EQUID^E, OR HORSES. 221

of skeletons found at Solutre point to the so-
called Ardennes horse, one of the long-headed races
of the domestic horse. One feels tempted to look
round and see whether there are not other
horses that approach as close to the Solutre branch.
In doing this we think, in the first place, of the

small horse that lives in a semi-wild state on the

•

Carmargue, in the delta of the Rhone. There also
exist in Alsace the last offshoots of an old race of
this kind. In stature and proportions these ani-
mals resemble large ponies. The head, in the
specimens wrhich seem most purely to represent
the race, is large and ugly, but the body, in spite of
the want of actual care, is well formed ; the limbs
very powerful. The animals, which are good-
natured and easy to manage, perform extraordinary
feats in the way of drawing weights. At times,
when there is little work doing, they are kept for
weeks in the meadows to the east of Schlett-stadt,
and are met with, in fact, in other districts besides
Schlett-stadt as far as the Rhine.

To throw proper light upon this possible con-
nection, it would be necessary to make the most
careful examination and measurements of the
various parts of the skeleton, and this has not yet
been done. How this would have to be done has

222 THE MAMMALIA.

been shown very recently by the distinguished
authority on the Diluvial mammals of Central
Europe, Professor Nehring of Berlin, in his ex-
ceedingly interesting studies on the fossil horses of
the German Diluvial deposits, and their relation to
the living horses.1 The Italian paleontologist,
Forsyth-Major, had, somewhat previously, in an
admirable manner, compared the Diluvial horse in
Italy with the present animal. In order to obtain
a good starting-point for an investigation of this
kind, it is necessary first to understand a few of the
principal species of the domestic horse. Of these
we require only the two groups in which, according
to French investigators, the domestic horse appears,
and into which, moreover, the eight races may be
subdivided. In the horses of the principal Oriental
race, the portion of the skull covering the brain is
strongly developed, the facial part of the head is
smaller, which circumstance is expressed mainly
by the breadth of the forehead. The inner side of
the crescents of the molars of the upper jaw
(Fig. 37) has a covering of enamel with but few
folds; the bones of the limbs are graceful, but
of a very firm structure. An admirable represen-

1 Nehring, Fossile Pferde aus deutschen Diluvialablagertmgcn
und ihre Beziehungen zu den lebenden Pferden. Berlin, 1884.

THE EQUID.E, OR HORSES. 223

tative of these qualities is found in the Arabian
horse.

' The Occidental Horse, says Nehring — following
Frank of Munich, who was the first to distinguish
this main race — ' shows itself, as regards the two
first mentioned points, to be the exact reverse of the
Oriental horse ; for its distinguishing character is
the much larger development of the facial portion
of the skull, as compared with the part covering
the brain. The skull seems to be comparatively
long and narrow with a small breadth of forehead.
The rims of the eye-cavities stand somewhat for-
ward. The enamel folds of the so-called crescents
of the molars of the upper jaw are very complicated.
The bones of the limbs of the Occidental horse are
of a thick and massive build, while in structure
they are less substantial and hard than in the case
of the Oriental horse.'

To this Occidental race, in Germany, belongs
our common-middle-sized horse, which of late years
has been more and more set aside to make room
for a mixed race ; for the State and private persons
have taken the breeding of horses into their own
hands and introduced foreign animals, more par-
ticularly of the Oriental species. Thus, for example,
during some decades, crossings from the Arabian

224 THE MAMMALIA.

breed, especially with the famous stud at Graditz
near Torgan, was systematically encouraged in the
districts on the Elhe in Saxony.

The heavy horse of Central Germany has been
termed the Equus cdballus germanicus by Sanson,
and by Pietrement after him. There were only
uncertain conjectures as to its origin, yet the
general opinion appeared to be that, like all the
medium-sized and larger European races, it was of
Asiatic origin, and that it had been tamed and
introduced by different nomadic tribes in prehistoric
times.1 This question, which claims our whole
interest, for it affects the history of the noblest of
our domestic animals, has advanced one stage in
clearness. Nehring has undeniably proved that a
Diluvial horse of Central Germany — numerous re-
mains of which have been discovered at Westeregeln

1 ' The Roman authors, Caesar in particular, distinguish in
Gaul and Germany between a native race of horses, which was
small and unremarkable although hardy, and between foreign
breeds that were larger and nobler in appearance. And many
other writers of ancient and later times speak of foreign horses
in contradistinction to the native breeds, so that there is, pro-
bably, no doubt that there existed in those days, in Germany,
two races strikingly different in outer appearance. That the
small native race must be traced to the tamed wild horse of
Europe, may probably be considered as certain, so that the only
remaining question is, of what origin was that foreign horse, and
whence did it come to us ? '— Al. Ecker.

THE EQUID.E, OR HORSES. 225

near Magdeburg, and at Tliiede in Brunswick —
tallies in all characteristic features with the heavy
Occidental horse. Hence it had not been introduced,
but had been tamed and reared by our ancestors
from the wild race which they found there. This
narrow-browed animal lived also on the Rhine, in
the neighbourhood of Remagen ; ' in the form of
its skull and the rims round the eye-cavities it
resembles our old medium-sized lowland races.'

Nehring sums up his views regarding the Ger-
man Diluvial horse and its relation to the present
tamed and wild races, in the following passage of
general interest : ' The Diluvial horse of our
country, like that of the neighbouring European
lands, was an untamed, wild animal which roamed
about, and seems to have lived in especially large
numbers in the districts round the Hartz Moun-
tains. ' These districts, during one distinctly longer
division of the Diluvial period, possessed a vegeta.-
tion of the steppe species and a corresponding
climate. The forest had become greatly reduced
during the Ice period (i.e. the first ice period, if we
are to admit of there having been two). On these
steppe-like tracts wild horses lived in large herds,
together with jerboas, steppe-susliks, loganiys, hare-
rats, numerous wild mice, and other characteristic
21

226 THE MAMMALIA.

inhabitants of the present steppes beyond the
Volga.1

* Their existence was now and again endangered
by a few isolated lions, also by wolves, whereas
hyenas (remains of which are not unfrequently
met with at Westeregeln) probably seized only the
carcases and scarcely ventured to attack the live
horses.

' The worst enemy of the Diluvial horse was
man. We know by numberless investigations, that
the human inhabitants of Central and Western
Europe in those days lived almost entirely upon
the hunting of horses ; the bones and teeth — very
probably the skins, hair, and sinews also — were made
use of iii a variety of ways.' Nehring, whom we
have been quoting, goes on to say how all this was
done, what proofs we have of the occasional visit
of nomadic tribes to certain localities, and how a
regular system of breeding arose gradually from
single attempts, and then adds :

* Those of my readers who are accessible to
scientific proofs will, I hope, find my detailed com-
parisons sufficient to convince them that an essen-
tial portion of our so-called heavy (common) horses
must be traced back to the heavy, thick-boned
Diluvial horse.'

1 Compare above, p. 76, i'oi.

THE PROBOSCID^E, OR ELEPHANTS. 227

The horse from Solutre, and the thick-boned
animal of Central Germany, are two local races
very nearly related, but yet distinguishable. There
is another race which has been found most com-
plete round about Schussenried in south-western
Wiirteinberg ; it has been described by the eminent
man of science, Fraas, who also gives an account of
many of the other Diluvial inhabitants of that dis-
trict. This horse is distinguished by its compara-
tively broad forehead and by the gracefulness of its
limbs, and hence agrees in important points with
the Oriental domestic horse. Now there have been
discovered in many of the prehistoric deposits of
the Bronze period, the remains of a tamed, thin-
boned horse, which has universally been supposed
to be of Asiatic origin. It cannot well be doubted
that this horse was imported by the tribes that
overran Europe from the East; yet it is equally
possible and probable, that a portion of the slimmer,
tamed horses of the Bronze period had been pro-
duced through the taming of the broad-browed
Diluvial horse of South Germany.

5. THE PROBOSCID^, OR ELEPHANTS.

The circumstances of nutrition which determine
the general character of the dentition and of the

228 THE MAMMALIA.

structure of the feet of animals, account for the
fact that the trunked-animals have always been
classed with the genuine hoofed animals ; but any
attempt at a closer definition of the older system,
with its many-hoofed animals and thick-skinned
animals, always led to the isolation of the ele-
phants. Their dentition shows no link whatever
with those of the present animals. And in causal
connection with the dentition we have the strange
shape of the skull, and again connected with the
latter the development of the proboscis, which in a
wonderful manner counterbalances the weight and
awkwardness of the head and neck. Probosces are
met with in other mammals : thus we have the
lip-finger of the rhinoceroses and the prominent
lip and nose of the tapirs and of the saiga-antelope.
Moreover, our excellent anatomist Burmeister
(whether rightly or wrongly I do not venture to
say) has equipped the Macrauchcnia, probably one
of the horse family from the Pliocene deposits of
Patagonia, with an appendage resembling an ele-
phant's trunk (Fig. 39).

Be that as it may, at all events our present Ele-
phant is one of the strangest and most enigmatical
forms, which, moreover, must have impressed
uncivilised nations in an extraordinary manner.

THE PROBOSCID^:, OK ELEPHANTS.

229

"\Ye do not put much faith in the Indian legend,
according to which the monsters which the
Great Spirit destroyed by lightnings, and which
died without leaving offspring, were Mastodons
(which existed in America as the earliest contem-

FIG. 39. — Macrauchenia patagonla. After Burmeister.

poraries of man), still, A. W. Schlegel as early as
1883 ! pointed out in one of his classic inquiries
that the influence exercised by the elephants upon
the imagination of the Hindoos was positively all-

1 A. W. Schlegel, Indische Bibliothek, 1823.

230 THE MAMMALIA

powerful. The Hindoos marvelled at everything in
the animal, not only at its sagacity, which made it
seem to them the embodiment of the god Ganesa,
but also — and more justly than we — they admired
the neatness of its feet.

Its zoological singularity is, as already stated,
mainly centred in the character of its head. To-
gether with an unusually small breadth of head,
the facial portion shows a remarkable height. The
narrowness is caused by the very limited number
of teeth. In the upper jaw there are only the two
tusks (incisors) and one molar on either side ; in
the lower jaw there are molars only, powerfully
developed, it is true, but, as regards length, show
comparatively far less dimension than is seen in
the full dentition of a grass-eater. All the more
powerful and higher are the roots, not only of the
tusks but of the molars. The latter are changed
six times, so that the succeeding teeth from be-
hind and below claim a position in the inside of
the jaw till the animal is tolerably advanced in
years. The structure of the molar, even when
worn smooth by use, shows it to be an exceedingly
perfect apparatus for crushing leaves and grasses.
Zoology terms it * complex.' It appears to be
formed of a large number of high and narrow

THE PROBOSCIDJE, OR ELEPHANTS. 231

cases of enamel which are filled with dentine and
joined into one mass by cement. This account of
the formation of the tooth, which is universally
accepted by descriptive zoology, is, however, as we
shall see, not correct, and very unnecessarily makes
the gap — which does exist between the Elephants
and the other plant-eaters — appear greater than
need be.

Even Cuvier distinguished among the Elephants
a group of fossil trunk-bearers, perfectly of the
elephant type, but with a more complete dentition ;
the molars, although less large than those of the
elephants, being characterised by nipple- shaped
eminences or tubercles in pairs, forming a number
of transverse ridges. Cuvier called the genus
Mastodon.1 A mastodon tooth of this kind (Fig.
40) presents nothing specially striking apart from
its often remarkable size. The crown, however, is
distinguished by the extraordinary strength of the
connecting layer of enamel which does not pene-
trate in folds into the interior. Now, as three
molars of this kind with huge tuberculated crowns

1 The most important contributions on this subject are :
Vacek, ' Ueber osterreichische Mastodonten und ihre Beziehungen
zu den Mastodonten Europa's,' Abhandlungen der geologischen
Reichsanstalt, vii. : most admirable also is the chapter on the
' Elephantoides ' in Gaudry's Mammiferes iertiaires.

232

THE MAMMALIA.

are met with in a row at the same time (for
instance, in the widely distributed Mastodon angus-
tidens) ; and as, moreover, they follow upon one
another as milk teeth and permanent teeth ; and,
further, as several typical mastodons of this kind

FIG. 40.— The used Molar of Mastodon angustidens.
a a', b b1, cc', Transverse ridges ; one-half nat. size.

have, besides the upper tusks, lower ones as well,
and between them other two smaller incisors,
this species of dentition moves wholly within
the limits and forms known to us. The mastodons
referred to are those of the Middle and Upper

THE PROBOSCIM:, OK ELEPHANTS.

233

Miocene, which survived longer in America than in
the Old World, and one of which continued to exist
up to the period of the Diluvial deposits and turf
formations, most probably even up to the prehis-
toric times of the human race. This is the so-
called Ohio animal, the Mastodon giganteum.

FIG. 41. - Portion of a Molar of Mastodon elephantoides.
One-half nat. size. After Clift.

As early as the Upper Miocene we meet with
animals of the Mastodon species, with molars, the
ridges of which are much more sharply denned and
resemble rows of miniature roofs (Fig. 41), inas-
much as they consist of numerous small tubercles,
which almost coalesce with one another. The tops

234 THE MAMMALIA,

of these tubercles become more or less rubbed off
with age. Only in some cases are the furrows
between the ridges of the tooth somewhat filled with
cement. These differing varieties and intermediate
forms have obviously proceeded from the earlier
mastodons, and in order to simplify the arrange-
ment have been classed as the genus Stegodon.
Their home was chiefly in Italy, whence they
spread abroad as far as Japan.1 The discovery of
their remains in the Japanese Archipelago is a
proof that these islands did not lose their connection
with the continent till comparatively recent times.
These teeth prepare us for the molar of the
true elephant, the latest form of the group. It
originates — and indeed not in theory but in the
actual transition forms up to the living species —
by the ridges continuing to become steeper, drawing
closer to one another, and sinking down almost to
the root of the tooth, and by these furrows be-
coming filled with cement, which thence covers the
whole outward surfaces of the tooth. The enamel
parts of the still unused tooth — although in form
and extent extraordinarily changed— nevertheless
show the same connection as in the species from

1 Naumann, Ueber japanische ElepJianten der Vorzcit
Palceontographica, vi. 1882.

THE PROBOSCID^:, OR ELEPHANTS.

235

which we started. A comparison of Figs. 40, 41,
42 will make the homology of the spaces a a', b b',
c c' perfectly clear.

Europe, before the appearance of the Glacia

Fio. 42.— Piece of a Molar of the Mammoth, cut longitudinally,

Nat. size.
e, Enamel ; d, dentine ; c, cement.

period, possessed several elephants, and Britain,
which at that time had not yet been rent asunder
from the continent, possessed the Elephas antiquus,
and Italy the Elephas meridionalis. The Mammoth

236 THE MAMMALIA.

also — the Elcplms primigenius, the most frequently
mentioned and most widely distributed animal of
the group — had heen driven from Asia into Central
Europe, whether as far as England is still uncer-
tain. It had an associate in the Elephas antiquus ;
but in any case the mammoth survived it up to the
period of man. Yet it can scarcely be said whether
— at the time the human immigrant took possession
of Europe, and the struggle began between the
tamed and the wild races, between man and the
wolf in England, and the lion in Thessaly — the
mammoth was exterminated in this kind of
struggle, or whether it succumbed to climatic, i.e.
to natural influences unknown to us.1

In entering upon a discussion of the elephants
as a class, it was our wish to do away with what
mystery seemed to encompass the existence of the
present animal, and we have done so by pointing
out their undoubted descent from the Miocene
mastodons. There is but one other step backwards
that we can take in explanation of the connection,
by bringing forward another of the colossal, thick-
skinned animals, the Dinothcrium. Up to within
very recent times only its skull was known (Fig.

1 Dawkins, ' The British Pleistocene Mammalia,' Palczonto-
fjraphical Society, 1878, xxxii. ; Adams, ' Monograph on the
British Fossil Elephants,' Ibid. 1877.

THE PEOBOSCID^E, OR ELEPHANTS. 237

48), from which it was supposed to be a footless,
aquatic animal, and that, by means of its two
tusks which projected from the lower jaws and
curved downwards, it probably moored itself to the
shore while resting or sleeping. No whole skeleton
of this animal has, it is true, yet been discovered
in connection with
the skull, but to
judge from various

remains of bones,

i • -u • 11 »»— i -- M t

which in all pro- m5r ^ : E? >

bability belonged to
it, it seems certain
that the structure
of the Dinotherium
was of the Elephant
species, and that

Some kind of pro- FIG. 43.— Skull of Dinotherium gigan-

boscis must be sup- teum" One twenty-fourth nat- size-
posed to have been suspended from the elongated
nasal bones. It is restored thus in our most eminent
works on palaeontology, and the correctness of the
supposition is confirmed by a comparison of the
molars with those of the early mastodons. The
form and manner of succession of these molars, five
being able to be in use at the same time, lead to
22

238 THE MAMMALIA.

the conclusion that the molars of the older masto-
dons originated from those of the Dinotherium by
the loss of one or more of the front milk-teeth as the
result of the strengthening of the true molars. But
as the known DinotheridsB and the earlier masto-
dons occur in almost the same geological horizons,
the supposed descent cannot, of course, signify that
Dinotherium giganteum had changed into the Mas-
todon angmtidens, hut only indicates the way-
where and how — the mastodons have originated
from ancestors of the Dinotherium species.

As is evident from Weinsheimer's classification l
— our latest authority for the species — remains of
the Dinotherium, and more especially molars and
lower jawbones, are found in various parts of the
Old World ; but in all cases, only in the Tertiary
deposits, and in no case higher than in the Upper
Miocene strata ; it ranged from France as far as
India. In England no traces of it have been
found, and its southern limit in Europe is Greece
(Pikermi). Notwithstanding the different forms
and sizes of the teeth — according to which fifteen
species have been distinguished — still, owing to
the transitions met with everywhere, we are in-

1 Weinsheimer, Ueber Dinotherium giganteum, K, Berlin,
1883.

THE PROBOSCID2E, OR ELEPHANTS. 239

clined, with Weinsheimer, to assume only one
species, the Dinotherium ; we are also glad to be
reminded by him of Suess' words : ' We can readily
convince ourselves that physical changes occur
without the mammal of the district being much
affected by them, but we find no change in the
animal world without a change in the outward
circumstances, without some recognisable episode.'
The changes in the dentition of the Dinotheriae
(which appear somewhat earlier than the masto-
dons) to the elephants proper, correspond with the
gradual change in their food and mode of life.
The Dinotheriae and the older mastodons had to
subsist mainly upon the roots and stalks of water-
plants, which they tore up with their lower tusks
in the morasses of tropical climes, like the rhinoce-
roses. Harder grasses demanded and produced
the transformation of the simple ridged tooth,
the tuberculate teeth of the mastodons, the fall-
ing away of the front milk-teeth, and finally a
concentration of the material force, and more
especially the peculiar conformation of the molar
of the later and present elephants.1 They certainly

1 ' All the changes of the organisation which we may observe
in the later forms of Mastodon as compared with the earlier
ones — for instance, the different forms of the incisors, the re-
duction of the symphysis (i.e. the connecting parts of the lower

240 THE MAMMALIA.

have differentiated much more from the original
form than the other plant-eaters ; hut even in the
case of these latter, a similar course from the
general disposition to the specialised form of to-day
has heen pointed out. Thus, at the close of this
short chapter, our elephants cannot any longer he
said to stand as inexplicable wonders of creation.

In the Middle Eocene deposits westwards of the
Rocky Mountains, there have heen discovered, among
many other animal forms, numerous remains of
powerful plant-eaters of the size of elephants ; their
skull possessed two or three pairs of horns, and
the upper jaw showed gigantic canines (Fig. 44).
These Dinocerata are believed by Marsh and Cope
(and with some degree of probability) to be de-
scendants of the Coryphodonta (see above, p. 199),
and although the possibility of their being related
to trunked-animals is not excluded, still meanwhile
it is a mere vague analogy. The Brontotheriae
from the Lower Miocene eastwards of the Rocky
Mountains, which are likewise colossal creatures,

half of the jaw), the increased slowness in the succession of the
teeth, and the corresponding increase in the number of ridges,
in short, the dentine which by degrees becomes worn off— point to
the fact that the later mastodons had discontinued the mode of
life practised by their ancestors, and had adapted themselves to
a life on land.'

THE PKOBOSCID^:, OK ELEPHANTS.

241

but less striking as regards the formation of their
skull, may, with somewhat greater certainty, be
classed as a branch of the Bhinoceros tribe (see
above, p. 199). Both groups, however, strike us
nevertheless as somewhat strange, chiefly because
their brain can be compared only with that of
certain fossil reptiles, considering the size of the

FIG. 44.- Skull of Dinoceras mirabile. One-nineteenth.

After Marsh.

skull and the thickness and mass of the spinal
marrow. It would seem to be a lower form even
than that of the Marsupials and the Monotrema.

Two other small groups are allied to the Hoofed
Animals, but in regard to one of these, the genus
Hyrax (rock conies) , no more can be said to-day

242 THE MAMMALIA.

than what was known to Cuvier. Although the two
groups, in their outward appearance and mode of
life, show affinity to the Rodents with claw-like
hoofs, their molar teeth are singularly like those of
most of the Ehinoceros trihe. There is absolutely
no safe starting point for their historical descent.1
We are more fortunate as regards the class next
to be considered, the Sirenia.

6. THE SIRENIA, OR SEA-COWS.2

Of this group the dugong (Halicore dugong)
lives in the Ked Sea, the Manatus frequents the
West Coast of Africa, and another species the

1 Cope is inclined to think that the arrangement of the
carpals in the Hyrax is a sign of very ancient descent. His
main reason for this supposition is the fact that the bones form-
ing the several rays of the fingers still lie one behind the other
simply and regularly, as in the case of the lower vertebrates ;
whereas in other mammals— not, however, in the elephant — the
two rows of carpals have been displaced and lie side by side.
The cause of this displacing or twisting must, without doubt, be
looked for in the loss of the thumb, which again is connected
with the cases of adaptive and inadaptive transformations of the
carpals mentioned by Kowalewsky. As, however, in the elephants
the row of carpals is not displaced, while in the Coryphodons a
very marked displacement has taken place in spite of the thumb
having been retained, it seems to me that Cope's attempt to
arrange and determine the general relationships of the Hoofed
Animals, more particularly of the earliest Eocene fauna, from
these circumstances, is much too unsafe.

- Lepsius, HalitJierimn Schinzii. Darmstadt, 1881.

THE SIRENIA, OR SEA-COWS. 243

eastern shores of America. Another and fourth
species of very remarkable form, the Pihytina
stelleri, belonged to our present period, but owing
to the smallness of the range of its distribution,
seems to have become extinct between the years
1741-48.

The earlier systems of zoology considered the
want of hind legs in Whales and the Sirenia, the
paddle-shaped form of their front limbs, and the
formation of the end of the body into an horizon-
tally extended fin, to constitute the characteristic
features of a distinct order of animals, compared
with which other very marked differences in their
skull and dentition seemed of little importance.
However, nowadays we are so well acquainted
with the disappearance of the front or back
limbs, or of both extremities (in the case of
reptiles) as phenomena of convergence, without
this being considered a proof of any near blood-
relationship, that we no longer think of classing
the Sirenia with the Whales simply because of the
want of the hind limbs. The Whales are flesh-
eaters, the Sirenia plant- eaters ; the former, by
their relationship to the seals, belong to the order
of the Ferce, flesh-eaters in the narrower sense of

244 THE MAMMALIA.

the word ; the latter are a very ancient branch of
the Hoofed Animals.

Of the living Sirenia the Manatus shows the
fullest dentition with a change of teeth. It points
to an old Tertiary group found in Jamaica, the
Prorastomus sirenoides, whose molars are genuine
ridged teeth.

The other and more perfect line ends in the
present period with the so-called Steller's Sea-Cow
(Rhytina stelleri), which has recently become ex-
tinct. It had no true teeth for masticating pur-
poses, but, in place of molars, had large fibrous
structures on the gums, one on each side of each
jaw. These structures occur also in two of the
living species, but are less large. The dugong
already shows a considerable loss of teeth, but by
possessing them stands nearer to the earlier form
of Sirenia, which leads in a direct line back to the
Eocene Halitherium. The dental formula is :

.1 1? 3 4

i — — , p — , m -.
4 ?, c 1 ?' 3' 4

When comparing the genuine Hoofed Animals
with their ancestors, it was seen that the loss of
one or two toes took place as early as in the first
Tertiary division. It was only single genera, such

THE SIREXIA, OR SEA-COWS. 245

as Coryphodon, that still showed the old five-toed
extremity, an inheritance from Pre-Tertiary times.
However all the living Sirenians possess a five-
fingered hand. When, therefore, it is said that the
molars of Prorastomus are genuine ridged teeth,
these do not point to the true Lophiodonta and
tapirs, with their already reduced hand, but to
earlier ancestors on both sides. Thus things no
longer existing point to that very distant past,
which extends back beyond our actual observa-
tions. Even in the case of Halitherium all that
is left of the hind limb is the thigh-bone. This
bone, however, is still attached to the pelvis,
which is tolerably reduced, but has a socket. The
earliest Sirenians, therefore, had a less striking
form of skull, but, nevertheless, in their whole
appearance were already like the present living
species. From this it follows that the four*
footed mammals changed their abode for the sea,
and lost their hind limbs, before the Tertiary
period.

The living Sirenians have experienced a still
farther reduction of the pelvis ; it has become de-
tached from the vertebral column ; and even the
above-mentioned remnant of the hind limb, the
rudimentary thigh-bone, has wholly disappeared.

246 THE MAMMALIA.

7. THE CETACEA, OR WHALES.

Up to about the year 1840, our scientific
knowledge of the larger Whales was based almost
exclusively upon the dissection of a few stranded
animals made in most cases in a very superficial
manner. Skeletons of the animals could, of course,
be procured, and some complete specimens had been
set up in some of the museums. Their ribs, lower
jaws, and vertebrae had also been collected, and,
like the bones belonging to fossil elephants, were
chained to town-halls and churches, where they
were gazed at as the remains of giants, and pro-
bably also (as was the case with a mammoth's
thigh bone in Spain) were worshipped as the
reliques of saints of giant stature.

Owing to this manner of acquiring scientific
material, a fatal confusion had arisen in the names
given. It was about this time that Eschricht,
professor of physiology in Copenhagen, applied the
well-known lines — ' If thou the poet would' st under-
stand, Then must thou go to the poet's land,' —
to the Cetaceans. He did not visit them himself,
it is true, but his friend Holboll, who was for many
years inspector of the Danish colonies in Green-
land, under Look, at Eschricht 's request, to make

THE CETACEA, OR WHALES. 247

collections and observations on the shores of the
Arctic Ocean. Holboll furnished the museum of
Copenhagen with excellent material in the way of
skeletons, together with the softer portions of the
body, also whole animals of various ages, with
detailed accounts of the biological observations he
had made. All this information Eschricht1 made
use of in a classic work, where he traces the trans-
formation of the skull of the foetus (only some few
feet in length altogether) to that of the full-grown
giant, that framework which strikes the on-looker
at first as perplexingly strange. He cleared up the
relation between the bearded and the toothed Whales
by following up Geoffrey's discovery more minutely,
i.e. by showing that the foetus of the Bearded or
Whalebone wrhale possesses a number of small teeth,
which never cut through the gums, and subsequently
become completely re-absorbed, when the huge
sieve-like apparatus on the mucous membrane of
the gum appears. The rudimentary teeth of the
Whalebone whales, which never come into use, are

1 Eschricht, Zoologisch-anatomiscli-pliysiologisc'he Unterstich-
ungen ilber die nordischen Walthiere (Leipzig, 1849), of which
work there is an English translation ; also Brandt, ' Untersuch-
ungen iiber die fossilen und sub-fossilen Cetaceen Europas,'
Mem. Acad. Petersb., 1873 ; Van Beneden et Gervais, Osteographie
dcs Cetacts. Paris, 1868-80.

248 THE MAMMALIA.

final links in the chain of evidence that the Whale-
bone whales are the last members of a transformed
group which commenced with animals with four
toes and numerous teeth, and which by the gradual
diminution of the dentition have become Whale-
bone whales.

Still, the skull of the Whalebone whales shows so
much resemblance to that of the Dolphins and all
of the other toothed whales, that, were it not for
the discovery of teeth in the fetal animal, we should
be in doubt as to the unity of the two groups.
From the head of a dolphin only a few feet in
length, we may learn all about the peculiar trans-
formations just as well as from the head of a
Greenland whale. The mid jawbones (Fig. 45)
do not appear in front between the upper jaw-
bones, but are very much elongated, and fre-
quently lie somewhat irregularly, projecting beyond
the upper jawbone. The most striking changes,
however, are those of the middle head, and all this
can be traced to the rising up of the nasal cavities
— in all other mammals these lie horizontally or
obliquely towards the front — which form perpen-
dicular blow-holes close to the crown of the head.
Not only has the olfactory bone become raised,
but the nasal bones also, in most cases, have
been completely displaced from their position as

THE GET ACE A, OR WHALES.

249

coverings, and stand as perpendicular back walls to
the nose, while the frontal and parietal bones are
compressed and pushed aside in the most remark-
able manner. However, it would certainly not re-
quire a practised osteologist to construct the skull
of a whale from any certified bone. There is
nothing in the skull of the whale that could, in the

FIG. 45.- Skull of Delphinus lagenorhynchus. Gray.

z &, Mid-jawbones ; o 1; upper jawbone ; j, cheek-bone ; p, parietal ; s, frontal
bone ; », nasal bone ; e, olfactory bone. One-fifth nat. size.

slightest degree, lead to a connection between it
and the Sirenians (p. 243). Nevertheless, their hind
limbs, like those of the Sirenians, have disappeared
externally without leaving a trace of their former
existence ; the rudimentary pelvic bones that are
concealed in the flesh — sometimes with the last rem-
nant of the thigh-bone, very rarely with the shank
23

250

THE MAMMALIA.

— bear witness, however, to
their having possessed an-
cestors with four legs.1
The front limbs remain
wholly within the known
structure of the mammal
leg, as may be seen by
that of the dolphin on Fig.
46. The toothed whales
are almost without excep-
tion five-fingered, even
though in most cases the
thumb and the little finger
appear very much reduced.
This, moreover, shows them
to be geologically older than
the Whalebone whales ; for
of these only the smooth
whales (Balcend) possess five
fingers ; in the others the
thumb has completely dis-

1 The modifications which the
whales have experienced as mam-
mals in water, have been admir-
FIG. 46.— Eight Fore-limb of ably described by Prof. Flower,
Delphinus delphis. After ' Whales in the Past and Present,'
van Beneden and Gervais. Kosmos, vii. 1883.

ff

THE CETACEA, OR WHALES. 251

appeared. That the Whalebone whales are geologi-
cally younger than the smooth whales is likewise
proved by their generic characters, the furrow which
extends from the throat to the belly, and the
humped or fin-shaped protuberance on the back.
Hence not only does the preserved skull of one of the
most important group of the Whalebone whales
(the Cetotherium) oblige us to maintain the animal
to have been one of the smooth wlmles, but we are
also enabled, from this circumstance and the geo-
logical period, to conclude that these whales did not
possess either furrows on their breast or fins on
their back.

The time of the fullest development of the
Cetacea belongs to the Miocene period, when they
had associates in the large and also numerous small
Whalebone whales, for instance, the Cetotherium
just mentioned, which is closely related to the
present Bearded or Whalebone whales (from two to
ten feet long), and also the Dolphins and the Zeu-
glodonta. The last-mentioned group is formed of
the two entirely extinct genera, Zeuglodon and
Squalodon.

Brandt has in detail urged it as improbable
that Zeuglodon, as is often supposed, can be
regarded as an intermediate form between the

252 THE MAMMALIA.

seals and whales, the shape of the skull and
the strong nasal bones covering the nasal cavity
having been thought to indicate this. Their length
varies between twelve to seventy feet. They belong
in America to the Eocene, in Europe to the Mio-
cene period.

Squalodon approaches closer to the Dolphins
than does Zeuglodon, more particularly by the
position of the nasal bones and the corresponding
displacement of the other bones. Its teeth (Fig.
47), like those of the Zeuglodonta, remind one of

31 4

the Seals. The dental formula is : i — , c -, pin ,

7
ra -. The compressed molars, which are pyra-

midical in form, show a certain external resemblance
to the teeth of the Sharks.

As the Zeuglodonta — including the Squalodonta
— are not yet as far advanced in the transformation
of their skull as the Delphinidae, it has never oc-
curred to anyone to regard the Dolphins as ances-
tors of the Zeuglodonta. Such a supposition would
be as irrational as if we were to imagine the
Antelopes descended from Oxen. On the other
hand, however, as great a difficulty would have to
be faced were we to suppose that animals of the
Squalodon species had left descendants of the

THE CETACEA, OE WHALES.

253

Dolphin species. We do not speak of the dolphin-
like whales with reduced dentition — e.g. the Nar-
whales ; these are side branches of the main stem,
the members of which are distinguished by numer-
ous teeth of the same shape. The teeth are always
growing and have no closed roots, wherein they
resemble those of many of the reptiles. Now
Baume, for various
good reasons, has
made it seem probable
that the ever-growing
teeth of mammals are
an ancient inherit-

a

FIG. 47.— Tooth of Squalodon.

a, From the outside ; b, from the side.
After Suss.

ance, and that rooted
teeth, on the other
hand, are a new ac-
quisition. If Baume
is right in this, we
have no connecting
link for the Dolphins,
and naturally none either for the Whalebone whales.
All the three subdivisions — Zeuglodonta, Dolphins,
and Whalebone whales — are found side by side in
the Early Tertiary period, and the vertebrae of
whales have even been found in the Jura. How-
ever, all that can be said with certainty is that we

2-54 THE MAMMALIA.

have no idea in what period or under what circum-
stances whales came to he developed. What is
improhable is that they were descended directly
from reptile-like ancestors, independently of the
other mammals. None of their peculiarities point
directly to the Keptiles, and are all intelligihle as
modifications which were effected hy the land
animal in its transition to a life in water.

But of what kind were these ancestors ? Our
first thought turns to the Seals, which, of course,
have likewise adapted themselves to an aquatic
life. However, in their case, the hind limbs have
not in any way become reduced, and have only
changed their position to the pelvis ; whereas the
upper and lower parts of the leg are shortened, and
the feet have become broad and lengthened paddles.
Hence it cannot be imagined that these animals,
which are so admirably equipped for swimming,
could have struck out a new kind of adaptation.
There could not have been any use or necessity
for this. Hence a certain resemblance in the
teeth can only have been the result of convergence ;
and Prof. Flowers reminds us that this had long
pince been pointed out by Hunter,1 who says :

1 John Hunter, ' Observations on the Structure and Economy
of Whales,' Philoso. Trans. 1787.

TUE CETACEA, OR WHALES. 255

* There are numerous points in the structure of
whales which bring them much closer to the hoofed
animals than to the beasts of prey — for instance,
the complex stomach, the simple liver, the respi-
ratory organs, but mainly the reproductive organs,
and the stages relating to the development of the
foetus. Even the skull of Zeuglodon, which we
admitted shows a certain likeness to that of the
sea dog, shows as much agreement with that of the
earliest pig- shaped ungulates, except in the purely
adaptive character of the form of the teeth.' The
objection raised that whales are flesh-eaters, while
most of the Hoofed Animals are true plant-eaters,
has been very properly refuted by Prof. Flowers,
who points to the former predominance of omni-
vorous animals, and shows that, with the exception
of the Pigs, which have remained most faithful to
the ancient type, the Omnivora became more and
more true grass-eaters, while the others developed
a taste in an opposite direction. Piegular flesh-
eaters can either not accustom themselves to
vegetable food at all, or only in cases of emergency
— as we ourselves see daily with the cat or dog-
whereas we not unfrequently find instances of
the contrary. Cattle eat dried fish with evident
relish during a northern winter, as is well-known ;

256 THE MAMMALIA.

and, therefore, the whales may, in the widest
sense of the word, be classed with the primary
Hoofed Animals, which still possessed five toes and
differed as much, and even more, from the present
group as the primeval horses from the horses of
our day.

The period when whales were most abundant
was that of the Middle Tertiary, when, as already
stated, the present Europe- Asiatic continent was
for the most part under water. Brandt gives a
very graphic description how the Cetacea of those
temperate zones may have ceased to exist with the
disappearance of that ancient ocean. And as the
account is of general importance we will quote his
words : ' The dying out of marine animals appears
at first sight more strange than the dying out of
land animals. We are apt to imagine that the in-
habitants of the sea — in their far-reaching element
animated everywhere more or less by living creatures
— have a better opportunity of withdrawing from
such external influences as affected them injuriously,
without thereby experiencing a want of food, par-
ticularly if the hurtful changes were not sudden.
As an example of an earlier ocean of this kind,
extending from Western and Southern Europe to
Central Asia, we may take the immense ocean

THE CETACEA, OR WHALES. 257

which existed in the Miocene, and probably lasted
beyond that period ; when largest it extended to
the Arctic ocean, and also communicated with the
tropical seas in the south. An ocean of this kind
would not only confer a higher temperature upon
the central zones, but would also essentially con-
tribute to the warmth of the northern regions,
and further, would not merely favourably affect the
flora, but likewise give the fauna a very different
character to what it shows nowadays. This con-
dition was, however, by no means a permanent
one. The gradual rising of the land led to a
separation of the southern, sub-tropic or tropic
seas, and to a lessening of the extent of the great
ocean itself, and its temperature would likewise
decrease. This was still more the case, however,
with the great connecting sea in the north, more
particularly when its separation, and gradual dis-
appearance, resulted in its becoming more or
less detached basins. The former luxuriant and
fuller vegetation and animal life on the continent,
which had been favoured by a warmer and moister
climate, changed their character and became less
exuberant. Less organic matter being produced
on the land, less was carried to the ocean, where
it served numerous small marine animals as iood,

258 THE MAMMALIA.

while, at the same time, the afflux of fresh water
exercised a greater influence upon the lessened
amount of sea water. These circumstances, which
reduced the food of marine animals — nay, which
was obviously detrimental to their existence —were
accompanied, moreover, by the gradual separation
of the great ocean into numerous basins, occasioned
by the rising of the land already alluded to ; this
prevented the animals from migrating, and the
altered condition of the water increased even
further owing to the separation. As a proof of
this we have the Black Sea, the Caspian, and the
Aral Sea, which remained longest in connection,
and several other seas in Central Asia. Those
species of invertebrates and fishes which, owing
to their peculiar organisation, could exist only in
large, open seas, and not in an inland sea with a
lesser amount of salty substances, and were unable
to accommodate themselves to the change in the
physical, thermal, and biological conditions, died
out together with the Cetacea. Those that sur-
vived and were able to adapt themselves to circum-
stances, like some of the molluscs, &c., decreased
in size/

THE CANUTE, OK DOGS. 259

8. THE CARNIVORA, OR FLESH EATERS.

The group of our present flesh-eating mammals
which has been most carefully examined as regards
specialisation of the dentition, and whose geological
appearance has perhaps left most traces and points
of connection — is that of the Dogs, or Canidce. We
shall, therefore, take this group as the starting-
point for our comparative examination.

The dog, like all the other Carnivora, possesses
five toes on its front feet and four on the hind feet,
with non-retractile claws. Those who wish to
obtain even a limited view of the relationship
between the main genus Canis and some of the
sub-species, and various other forms allied to
these, their geographical distribution, &c., in the
hope of finding some indications of the lines
which partly vanish into primeval times with-
out leaving any trace, but again in many in-
stances showing a connection with definite palae-
ontological facts, must first of all make them-
selves acquainted with the dentition of the group.
One tooth more or less unmistakably determines
the date of one or more of the geological periods.
The position, size, and disappearance of the teeth in-
dicate, with almost the same certainty, the relation-

260 THE MAMMALIA.

ship between the species which ranged separated
over half of the earth's surface, or they point to
the different origin of those which live almost
within the same range of distribution. The
certainty with which a palaeontologist works — by
making use of means which appear absolutely
valueless to an unscientific person — can be appre-
ciated only by those who have acquired at least
some knowledge of the way in which the work is
accomplished. This again shows what little weight
can be placed in the perpetual assertions of un-
scientific persons, that the followers of the theory
of descent are not in the position to prove the
transformation of species.

Everyone knows that the dentition of the fox
(Cams vidpes) consists of very differently formed
teeth (Fig. 48), which, however, agree in so far
that the crowns show an unbroken covering of
enamel ; in this the molars, more especially, differ
strikingly from those of the Hoofed Animals and
many of the Eodents, where the crowns have com-
plicated folds of enamel. The dental formula

31 12

is: — i , c -, pm , in -. For our purpose here

3 1 4 3

it is the molars almost exclusively that come into

4 2

consideration, hence - : - . Thus the genus Dog

4 o

THE CANID^, OR DOGS.

261

has in the upper jaw four premolars or ieeth that
have replaced the milk-teeth, and two molars. Of
the premolars the fourth Q)4)is remarkable owing
to its size, compressed form and sharp edge, also
by possessing an inner process in front ; this is the
carnassial or ' flesh-tooth.' Corresponding with it

FIG. 48. — Jaw of the Fox. After Huxley.

below we have not the p*, but the first of the three
molars or grinders, m1. The connection and origin
of the different species of Dogs is determined by
the, in some cases, undistinguishable shades of
difference in the tubercles and processes, by the

distances of these points from each other, and by
24

262 THE MAMMALIA.

the length and breadth of the teeth, the measure-
ments of which have to be made by the tenths
of millimetres, and thus we finally have an
animal of the dog species of the present day not

2 4

with but with - molars, and we may there-
fore draw the very probable inference as to the
Eocene ancestors of the present Canidse. In the
above remarks we have principally followed an ex-
tremely clear account given by Huxley.1

If several small differences are taken into con-
sideration, the various species of the genus Dog
(Canis) may be formed into two groups, the one
represented by the Common Fox, the other by the
Brazil fox (Canis azarce). These differences relate
to the frontal depressions — which are entirely want-
ing in the fox and are strongly developed in the
other group — and to the form of the front part of
the brain. By the side of the fox we have Canis
fulvv£fargentatus, littoralis,zerda, lagopus and others;
on the other hand the Jackals and Wolves, all varie-
ties of the Domestic Dog, Canis anthus, latrans, an-
tarcticus, magellanicus, cancrivorus, varieties of the
Dingo. In both groups subdivisions have again to

1 Huxley, ' Cranial and Dental Characters of the Canidae,'
Proc. Zool Soc., 1880.

THE CANID.E, OE DOGS. 263

be made in accordance with the form and strength
of the carnassial tooth. However, even when a
good idea of the Fox and Wolf type has been ob-
tained, the differences finally merge one into the
other, and thus here again comes an end to al)
systematic arrangement.

In all the above-mentioned animals of the dog

2

species the dental formula of the molars is -. The

o

agreement of the lobes, processes, and tubercles of
the teeth is such, that blood-relationship appears
certain if the alternative of convergence or inherit-
ance is properly considered.

We must now refer to the question of the origin
of the domestic dog.1 That the whole line of foxes
has nothing to do with the dog has long been an esta-
blished fact. On the other hand, Darwin endea-
voured to prove that various wild tribes of men in
different parts of the globe tamed native wolf-like
animals, and that the crossings of these species and
breeding of various kinds produced the domestic
dog of our day. This opinion of Darwin's has been
somewhat modified by L. H. Jeitteles, a careful
authority on the domestic animals. According to

1 Darwin, The Variation of Plants and Animals under
Domestication ; Jeitteles, Die Stammvater unserer Hunde-Rassen.
Vienna, 1877.

264 THE MAMMALIA.

him the wolf (Canis lupus) has no connection with
the European and west-oriental races of Dogs, the
connection being mainly through the Jackal and
the Indian Wolf (Canis pallipes). The races partly
lead back into prehistoric times. Closest to the
Jackals we have the so-called Turf-dog, known
from the turf deposits of the lake dwellings, and
which is probably the ancestor of our Pomeranian
dogs. Allied to it we have the terriers and turn-
spits. From Canis pallipes is descended the so-
called Bronze-Dog, which most probably came to
Europe with human immigrants from Asia, and
with it the sheep-dog of Central Europe, the larger
sporting dog, the poodle, cur-dog, and bull- dog.
The ancestor of a third group may perhaps be
found hi the large jackal (Canis lupaster) of North
Africa, to which we should also have to refer the
ancient Egyptian dog, the Oriental street dog, and
the wild dog of Africa.

This does not as yet settle the question as to
which fossil forms may be concealed among the
numerous races of the domestic dog. Various con-
jectures have been made, none of which, however,
are based upon any special reasons. According to
Blainville's opinion, a Diluvial species of a gentle
and sociable nature — no longer existing in a wild

THE CANIM;, OR DOGS. 265

state — must have been the primeval form of the
domestic dog ; but after "what has been said above,
this general way of settling the question must be
regarded as one that no longer holds good. Wold-
rich's * views show a greater amount of probability,
and have lately been taken up again ; he maintains
that our domestic races are descended from several
wild forms of the Canidse of the Diluvium, and
herein he agrees with what Darwin and Huxley
have stated regarding the relation between the
Domestic Dog and the living Jackals and Wolves.

It may with certainty be maintained that the
direct ancestors of the European Wolf are to be found
in the Diluvial deposits. Formerly a huge animal
of the wolf species was distinguished as the Cave
Wolf, without there being any distinct character to
separate the two forms. A third form of wolf —
Canis suessii, from the Loss near Vienna — is de-
scribed as a slim but powerful animal, strong
enough even to pursue and overpower the larger
species of plant-eaters. It is, in fact, one of the
eight species of wolves which can be distinguished
during the Diluvial early ages of man. And in
addition to these there are about five kinds of foxes.

1 Woldrich, ' Wilde Caniden des Diluviums,' Wiener Denk-
schriften, 1879.

2G6

THE MAMMALIA.

In now returning to the living Canidse, several
species demand our attention, one of which is
described as Icticyon venations, a native of Brazil,
the other under the generic name of Cyon, inhabit-
ing the countries to the north and north-east of the
Altaian mountains. These dogs do not possess the
third molar in the lower jaw, and the m in the upper
jaw is so small that a reduction appears to be immi-

FIG. 49. — Lower Jaw of Icticyon. After Huxley.

nent there as well. It is in the natural course of
things that one or both of the first premolars, or
the last molar, should become useless and forced to
disappear, by the neighbouring teeth being specially
taken into requisition, although in most cases we
do not know the immediate reason of this.1 The

1 Any of our readers who can examine the head of a dachs-
hund may convince themselves of the fact that the first pre-
molar above and below can scarcely be of any use to the animal ;

THE CANHLE, OR DOGS. 267

other circumstances of the structure of this group
do not lead us to expect anything special from this
concentration of the dentition. In former times,
however, as we shall soon see, a most varied develop-
ment of new genera of Beasts of Prey began with
dog-like animals.

Much more interesting for the purpose of our
investigation here is the Otocyon lalandii, the spoon-
dog of South Africa, so called from the peculiar
formation of the skull. Its habits show an approxi-
mation to the Foxes, yet as regards dentition it does
not show this affinity, inasmuch as it possesses

4 4

- : - molars, and also shows the most remarkable
4 4

differences in the relative size of the single teeth.
As already said, the spoon-dog is in many ways,
and as regards dentition, shaped after the fashion
of the dog type, and can thus scarcely be dragged
out of this connection, and we are compelled to
look upon it as a still existing primary form of dog.
The whole palaeontology of the Vertebrates shows
that the many-toothedness of Mammals is an
inheritance from their lower ancestors, and that

it is a little stump which does not come in contact with the
opposite row of teeth, and is frequently wanting altogether. If
the dachshund is not forcibly suppressed as a species, its denti-
tion will one day inevitably be reduced by one premolar.

268 THE MAMMALIA.

any increase of the teeth within a class has prob-
ably never taken place.

2 2
As our dogs, with their - : - molars, have no

doubt been descended from fuller-toothed animals,
Otocyon must be regarded as the still Irving
representative of the early type of dog, which in
other characteristics shows more affinity to the fox
family. But as there also exist species of the group
Canis azarce with very small frontal depressions, it
is, as Huxley says, very difficult not to imagine that
these too must be traced to ancestors of the Otocyon
type. From this species, therefore, we should have
to derive the two lines which diverge into the fox
on the one hand, and the wolf on the other. We
are supported in this view by the observation that
the South American Canis cancrivorus often pos-
sesses the ??i4, and thus shows itself to be another
remnant of the primary form. A fourth super-
numerary molar of this kind is not a monstrosity
or pathological phenomenon, but an atavism or
reversion of the same sort as the so-called wolf's
tooth in Horses, which was explained as a pre-
molar which existed in the primary genus Anchi-
therium.

Hence the key to the derivation of all the Dog

THE CANIDJE, OR DOGS. 269

tribe is to be found in their relation to the spoon-
dog. What Huxley states regarding the simi-
larity between its dentition and that of the lower
bear-like genera is certainly well worth conside-
ration, but is of less importance than the con-
clusion he draws from a discovery of his own. In
several hundred different species of Dogs he
found fibrous formations which are said to corre-
spond with the marsupial bones (ossa epipubica), the
distinguishing feature of the Marsupial group. If
this observation becomes an established fact, the
direct descent of dogs from Marsupials would seem
in the highest degree probable. However, as one
of our first comparative anatomists has maintained,
we still require further proofs for Huxley's observa-
tion. In imagining the Dogs connected with the
Marsupials we should not, in the first instance,
have to consider our present carnivorous Marsu-
pials (Thylacmus, Dasyurus), whose row of molars
consist of one tooth less than that of Otocyon,

and are generally characterised as p -, m -. The

'± 4

Marsupial Eats would more likely have to be taken
into consideration. They are the only known
animals from the Eocene with four molars. More-
over, by using the flat part of their hands and feet,

270 THE MAMMALIA.

and possessing pointed, tuberculate molars, they
point to the Insectivora. For another circumstance
to be considered is, that various peculiarities in the
teeth of the lower Canidae show approximation to
the dentition of the Insectivora ; and the occurrence
of rudimentary clavicles and the rudiment of a
fifth toe on the hind limb, also clearly point to
ancestors with well-developed clavicles, and the full
number of five toes. All this is found united in
the Insectivora : hence our present dogs have been
traced back to the Eocene and Pre-Eocene Insect-
eaters with certain peculiarities of the Marsupials.
This derivation of the Dog tribe — which is based
mainly upon deductions from the present nature
and distribution of the group — goes back, therefore,
into that dim twilight which, in the opinion of
Cuvier and his followers, could alone precede the
dawn of true light in the mammal world. We
shall have to dwell a little in this Eocene period
and look around among the incredible wealth of
mammal forms, which seem, as it were, to have been
re-animated by Filhol's graphic descriptions (see
above, p. 64). We shall obtain some idea of the
vigour of that exuberant, plastic life if, in place of
the few Carnivora that are now inhabiting France,
and indeed Southern and Central Europe, we ima-

THE CANID^E, OR DOGS. 271

gine in one part of South-western France, of Carni-
vora alone, some forty species from the size of the
marten up to that of the most powerful wolves and
bears. They lived, as the vast quantities of their
remains testify, partly in herds ; and of food there
was an abundance in the corresponding numbers
and varieties of plant-eaters.

First of all comes the Viverrine Dog (Cynodictis),
which, although possessing the dental formula of
the Dog

.31 4 2

(of which, in the upper jaw the fourth premolar, in
the lower jaw the first molar stands for the carnas-
sial tooth) had a very narrow skull, with broad,
strong cheek-bones — an admirably developed beast
of prey between the size of a fox and a wolf.
These animals, Filhol says, are curious and very
peculiar forms, in which, after a very careful ex-
amination, certain points are at length discovered
by which they show affinity with our present
Carnivora. But in spite of every effort to bring
them under one head, it cannot be done. And
hence we have to assign to them an essentially
distinctive character, a position outside the cus-
tomary classification, and one, in fact, which

272 THE MAMMALIA.

approximates the living families. The French
investigator means to say that they are dog-like
animals, but not dogs ; that, in fact, they cannot
be classed with any one of the present families
of Carnivora, although showing the character-
istics of the class in the various parts of their
skull with which we are very well acquainted — the
mid jawbone, gums, alar processes, tympanic bones
— as well as the form of the skull as a whole. We
should not exactly say that the animals stand be-
yond our system of arrangement, but that they do
away with existing gaps. This is most obviously
the case with their dentition. In most of these
forms of Cynodictis — which can be denned as
species — the teeth are all well marked and developed
according to their position. But in Cynodictis inter-
medius, the last lower molar, ??i3, is so small that it
is evidently of not much use, and we may rely upon
its gradual disappearance. Were this to happen
we should then have the dental formula of the
Viverrae. And it does happen : the race named
Cynodictis intermedius viverroides from the C. inter-
medius has become a Viverra.

With the loss of that molar there arises a small
modification, p*, hence one connected with the im-
portant carnassial tooth of the lower jaw; and

THE CANIDJE, oil DOGS. 273

what is most remarkable, the same loss is met with
in two other species (C. crassirostris, leptorhynchus),
the same modification of the carnassial tooth. It
is not known what change in the mode of life
caused these same changes in the teeth in several
different species. We are content with knowing in
what manner so-called new species and genera
appear on our earth ; in fact, not suddenly, but
by imperceptible shades of difference, which in-
crease in the course of thousands of generations,
until, finally, what seemed at first an exception to
the rule becomes the prevailing state of things.
The objection so frequently brought forward
that these ' accidental ' deviations would always
again be neutralised by crossings with unchanged
members of the species — if geographical isolation
did not come to assist them — have no founda-
tion whatever ; for our discoveries in palaeonto-
logy prove the contrary. It must be remembered
that the expression ' accident ' applies only in so
far as it conceals our ignorance of causes and
occasions. In many cases — for instance, in the
transformation of Mastodons into Elephants-
we can with some certainty determine the altered
conditions of food to which the teeth had to adapt

themselves.
25

274 THE MAMMALIA.

And in the present case we have only to deal
with an established fact, that the Viverrce are the
descendants of the Viverrine Dog, Cynodictis.
There can be no dispute about this. Hereupon
commences a new series of modifications, and from
the Viverrse are descended the Weasels.

We now pass from the Upper Eocene of the
phosphate of Quercy to a somewhat later period,
which produced the Lower Miocene deposits of
Saint Gerard le Puy, on the Allier. Here is found
the Plcsictis, a carnivorous animal distinguished
from the Viverrse mainly by the form of its head.
Filhol points out that a ' comb ' (crista) of the
sagittal suture not previously existing, has been
formed by a contracting of the temporal ' combs '
of the Cynodictis; in other words, that we
have the perfectly justifiable conclusion that
smaller species of Cynodictis passed over into the
form of Plesictis under the influence of natural
causes.

In the races directly descended from Cynodictis
a change takes place in the nature of the teeth, and
the dentition assumes more and more the character
of that of the weasel, while, on the other hand, the
peculiarities of the Yiverrae disappear ; thus the line
Plesictis — Stenoplesictis — Palaoprionodon leads in

THE CANIM:, OR DOGS. 275

gentle modifications to Mustela, and henceforth
there exist weasels.

Equally distinct are the intermediate forms
by which is accomplished the transition from the
weasel's dentition to that of the Cats. The genus
Procelurus appears likewise with two tuberculate
teeth in the upper jaw behind the carnassial tooth.
But single species of the genus sometimes show a
loss of the hack molar, and herein approach the
cats ; the back edge of their carnassial tooth, more-
over, loses a tubercular heel or process. By this
small modification Pro&lurus has become Pseud-
(elurus, inasmuch as the modification was general and
continued for some length of time. In comparing
the following statement of the simplification of the
molars of the lower jaw :

Premolars Carnassial Tubercular teeth

411 — PI mt
410 — p4 ml
310 — 233 mi

which have actually been observed, and which
shows, moreover, that the front premolar p* has
also become reduced — it becomes clear that the only
distinction between a Pseud&lurns of this kind, for
example, Ps. Edu-ardsii and our present cats, is that
it possesses a minute premolar. Hence the great
simplification in the number of teeth which Filhol

276 THE MAMMALIA.

was able to establish in these animals, justifies
the supposition that this small piece will disappear
later, in the same manner as has happened
previously to the one that existed in front of it (p}),
and had previously happened to the tuberculate
tooth (??i2). The genus Felts herewith appears upon
the scenes.

The concentration of the dentition did not re-
main stationary at the stage acquired by the cats,

P 5' m T » ^ie high^t degree of specialisation was
'_ 1

attained by the so-called Sabre-toothed tiger (Ma-
chairodus) with the dental formula :

.3 1 20

i - , c -, p — , m —

8 1 2' 1

with 26 teeth against 30 in the cats. Machairodus,
an animal somewhat the size of a tiger, possessed
in its upper jaw a powerful sabre- shaped canine
tooth w'hich projected from the mouth downwards
extending beyond the lower jaw. This lower jaw
shows an indentation obviously produced by the
pressure of the huge upper canine teeth as they
became more and more developed and endeavoured
to make room for themselves. The cause of the
dying out of this most definite of all the Carnivora
of the period, has been attributed to the extra-

THE CANID.E, OR DOGS. 277

ordinary development of these tusks, the length of
which finally may have prevented their opening
their jaws sufficiently. In answer to this it can
only be said that a bad hypothesis is better than
none. The sabre-toothed tiger appears and dis-
appears in the Miocene deposits both of the Old
and the New World.

Pseudizlurua was shown above to be an inter-
mediate form between the weasel and the cat.
This does not exclude other intermediate forms.
One of these is the sElurogale, also the size of a
tiger and found in great abundance in the phos-
phate of Quercy. Its upper jaw resembles that of
Cats, the lower jaw shows the teeth of the Muste-
lidse (weasels and otters). The races arrange them-
selves in such a manner that, notwithstanding the
extraordinary variations in the size of the teeth-
in those which deviate most from the primary
form — the lower jaw also has preserved the Cat
formula.1

1 We shall not refrain from pointing out the difficulty
which is met with in this apparently simple line of descent.
Of all the living Carnivora the Cats possess the most perfect
rudimentary clavicles, the others have either smaller traces of
these or none at all. All the ancestors of the Cats must at least
have possessed clavicles such as are still met with in the Cats.
And it is quite intelligible that the clavicles should have con-
tinued to exist in Cats, owing to their have retained the habit of

278 THE MAMMALIA.

In order to illustrate our remarks we have
drawn up the following piece of pedigree : —

Yiverrine dogs (Cynodictis)
VIVERK.E
Plesictis
Stenoplesictis

Premiums Palffioprionodon

I i

Pseudaslurus WEASELS

CATS

Sabre-toothed tiger

The above is the shortest way of expressing the
result of a long series of the most careful com-
parison of facts, and has as much right in claiming
to be credited as any other conclusion deduced from
scientific investigations, in whatever province the
facts have been gathered. When it is admitted that
the philologist can arrange the age, connection, and
succession of manuscripts, in a tabular form, from
the character of the writing, from the use of signs

climbing, while in the other animals they would become more
and more reduced. Naturally enough we do not know the
particulars connected with this reduction. But should we suc-
ceed in establishing the want or a greater reduction of the
clavicle in one of the branch families in the above pedigree
(arranged according to the development of their dentition) our
whole arrangement would of course collapse.

THE CANID.E, OR DOGS. 279

and word-forms, &c., and that the literary historian
may conclude that a certain work was written by
a certain author, from the style of the composition
and certain modes of expression, &c. ; and further,
when it is admitted that a lawyer, by the com-
bination of passages, all of -which are obscure, can
throw light upon a case of Koman law, then I
maintain our procedure also — a zoologico-palae-
ontological method of investigation and drawing
conclusions — must be granted as a matter of
course.

The descent of Weasels and Cats from those
changing forms of Cynodictis, therefore, presents a
great degree of probability but no actual certainty ;
for different animals that appear geologically almost
as contemporaries, may occur parallel with one
another with precisely similar dental formulas and
reductions in the jaw. However, we come to the
certain conviction that the transformations actually
took place, and that our present animal could and
must have originated in that natural manner.
And as it is mainly our wish merely to pave the
way for this opinion, it will be almost superfluous
to enter any more fully into the primary and tran-
sition forms between the present and the primeval
Carnivora.

280 THE MAMMALIA.

It may, however, be remarked that our B ars
had representatives in the Miocene. In those times
there existed the Amphicyon, of the size of a wolf,
but in reality a dog with _p4, w3, the broad crowns
of the first two molars showing the incomings of
tubercles which point to a definite form of food.
This characteristic is even more marked in a later
form of bear-dog, Hycenarctos (_p3, w2), and has
preserved its full development in the bear (Ursus)
from the Pliocene up to the present period. How-
ever, the fewer number of teeth of the Hyamarctos
again forbids its being classed with the actual
ancestral line of the Bears. The latter with their
flat tuberculate molars, which point to a fixed food,
and their tolerably blunt carnassials, are compara-
tively a late modification, to a certain extent a
reversion to the beast of prey. This character
has, however, been retained by the polar bear,
which has again become a pure flesh- and fish-
eater.

Gaudry has pointed out an ancestor for Hyaenas
in the genus Ictitherium from among the fauna
discovered at Pikermi. All that was required in
this animal to give its dentition the formula and
structure of that of the Hyaena, was the disappear-
ance of the second molar above and below (and the

THE CANID.E, OR DOGS. 281

upper one already shows signs of reduction), also
an extremely small difference in the carnassial
tooth. Indications even existed in the Ictitherium
of the peculiar strength of the premolars of our
present hyaenas, which show a predilection for
gnawing and crunching bones. Animals of the
Viverra type seem to have been the ancestors of
this branch.

In the Lower Eocene strata of Europe, but more
particularly in the corresponding deposits of North
America, numerous Carnivora have been found
which differ more from the living families than
most of the fossil genera that were brought into
connection with them above, and which, moreover,
can be brought into this connection, although,
taken as a whole, they prove to be but the first
stages of very highly developed beasts of prey from
the Upper Eocene. The characteristic which most
distinctly indicates the low position of the Early
Eocene beasts of prey, is the small development of
their brain, which is known to us from the form of
the skull, and from natural fillings and castings. In
their case the olfactory lobes appear as broad pro-
cesses of the fore end of the larger division of the
brain, the mid-brain being scarcely covered by it,
the back part not at all. As regards Europe, the

282 THE MAMMALIA.

Arctocyon (Palaocyon blainville) ' has long since
been known as an animal with a brain approaching
that of the Marsupial type ; whereas its dentition,
which resembles the earlier form of pig-shaped
animals, Entelodon, points to the Omnivora, while it
has also something of the bear as a flesh-eater.
Further, we must mention the Hyanodon and
Pterodon, so often referred to, and usually denned
as ' mixed forms ' ; they appear somewhat later, it
is true, but, nevertheless, show resemblances to the
Marsupials — for instance, in the form of their teeth
they are closely allied to the Thylacinse, though not
as regards their change of teeth.

"With these animals — which are partly also
found in America — Cope classes a whole series of
American genera of doubtful position mostly from
the Eocene ; he gives them the name of Creodonta,
and regards them as the ancestors of the subsequent
Carnivora proper. In their case the row of molars
is not separated definitely by a carnassial tooth, or
but imperfectly so : the jaws are lengthened, and
the muscles for chewing are placed in such a man-
ner that only a smaller degree of power can be
developed than in the subsequent true Carnivora ;

1 Lemoine, ' Kecherches sur les ossements fossiles dea
environs de Reims,' Annales des sciences nat., 1879.

THE CANID^E, OR DOGS. 283

these latter, by the shortening of their jaw and the
reduction of their dentition, were all the better able
to overpower their prey.

One of the most important forms of these Creo-
donta — because extremely numerous in New Mexico,
and found in three species in the phosphate of
Quercy — is Oxyana. The species vary in size
between a badger and a jaguar. The dental for-
mula is : i -, c -, pin -, m -. Herein, therefore,

the Eocene fauna of the Old and the New World
again show connection.

We are the less inclined to enter upon an
account of the five families of Creodonta,1 because
the grouping, the assumed connection, and, above
all, the derivation of our present large group of Car-
nivora, the dogs and cats, often seem to be in want
of those safe foundations pointing from case to
case, from genus to genus, which Filhol's investi-
gations and deductions have made so incontestable.

In order, however, to give those of our readers
specially interested in the subject some suggestions
for further enquiry, we may here mention the

1 Arctocynoidaa, Miacidas, Oxyamidas, Amblyctonidae, Meso-
nychidse.

284 THE MAMMALIA.

systematic relationship into which Cope ' has place
the Creodonta.

The mammals from the Wasatch beds of Utah
and of New Mexico have been divided into fifty-
four species, most of which are distinguished by a
very small and evidently low form of brain, to
judge from the structure and position of its pa.rts.
That of Coryphodon (Fig. 14) appears almost like
that of a reptile, and in this character the Hoofed
and Clawed Animals agree. They also agree in the
structure of their joints, the different parts of their
limbs, and also in the number of their toes, of
which five were observed in from forty-one to fifty-
four species. In the flesh-eaters there is no car-
nassial tooth ; in the plant-eaters no teeth with
crescentic crowns ; all the molars belong to the
type of tuberculate teeth, either in primitive sim-
plicity, or of that form where the tubercles are
compressed to the side, and coalesce into imperfect
transverse ridges. On this account the animals
have been named Bunotheria, and are arranged in
the following manner : —

Insectivora, Treniodonta, Tillodonta, Creodonta, Mesodonta

Bunotheria.

There can be no doubt that these Early Eocene

1 See p. 72, note.

THE CANIByE, OR DOGS. 285

animals — owing to the above-mentioned peculiari-
ties— show a certain necessity for being classed
together, and it is self-evident that they must stand
nearer to one another, were it only on account of
the smaller period of time since their separation
from the primary stock, which must be assumed to
have been common to them all. However, in our
opinion, the characteristics specified above go no
further than to indicate a most general form of con-
nection. When Cope maintains that the different
groups of Bunotheria are related to one another,
somewhat in the same way as are the orders of
Marsupials, it seems to us that this scarcely applies
to the case. To give an example : what has Tillo-
therium from the Eocene of Wyoming (Fig. 50) in
common with the flesh-eaters Arctocyon and
Oxy&na? By the smallness of its brain most
certainly nothing ; nor by its five toes, and the cir-
cumstance that the whole sole of the foot is applied
to the ground. The resemblances in the molars are
not remarkable, while the decidedly rodent- like form
of the incisors only proves the peculiarity of the
animal. Any typical feature — such as the marsupial
pouch or the marsupial bones, or the openings of
the urinary and genital organs peculiar to the Mar-
supials— is not met with in any of these animals,
26

286

THE MAMMALIA.

as far as can be judged from the often great paucity
of their remains.

Only one point stands out in this attempt to
throw light upon the relationships between the

Fia. 50. Skull of Tillotherium fodiens, from above. One-fourth

nat. size. After Marsh.

mammals of that early period ; the indrawing of
the Insectivora, of that type which has been pretty
faithfully preserved from the earliest traces of

THE SEALS. 287

Marsupials or Insectivora in the Trias down to the
present day, and which seems to have gradually
sent out off-shoots in the most different directions,
till at length they became unrecognisable.

9. THE SEALS.

According to the form of their skull, dentition,
and mode of life, Seals are * carnivorous animals
that have adapted themselves to a life in water,'
and in this way they are generally described. In
order to make the theory acceptable, it is customary
to point to our Sea-otter, which, unlike its nearest
relative that thirsts for warm blood, has become a
pure fish-eater. The Sea-otter uses its hind limbs
after the manner of seals, and its skull shows a
depression of a similar kind to that which has
proved advantageous to the Seals. Hence, so it
is said, we have to imagine the ancestors of the
Seals on that line which has led them farther and
farther from their original forms, which very gra-
dually changed their limbs into fin- shaped rudders
(while perfectly retaining the pelvis and the articu-
lation of the skeleton), and whose skull became a
light, thin-walled box not burdened with strong
teeth. Only the Walrus (Trichechus) has developed
a couple of heavy tusks, corresponding with its

288 THE MAMMALIA.

entirely different mode of life, inasmuch as it
burrows in the ground for certain kinds of mussels.
All the others hunt for fish, which they can readily
tear to pieces with their sharp canine teeth and
pointed molars, which are compressed somewhat to
the side.

Of fossils that might illustrate the gradual in-
coming of Seals there are none. We conclude that
the process must, at one time, have begun with
carnivorous land-animals. The idea that the re-
verse might have been the case by their having, as
sea-animals, taken to a life on land, has as little
value here as in the case of the Cetaceans, which
are mammals, and have never been anything else.
The period during which they changed their element
lies at an immeasurable distance in the far past,
but is probably less distant than that in which the
ancestors of the whales took to the sea while re-
ducing their hind limbs.

There can be no question about making the
Whales (of course only the toothed group) the
primary parents of the Seals. If any comparison of
the kind is thought of, the Eocene Zeuglodonta could
alone be taken into consideration. But even these
latter do not show any points of connection ; their
skull would have to be retro-metamorphosed to form

THE SEALS. 289

the skull of the seal, and their dentition would have
to be fuller ; hence the supposed points of connec-
tion would be confined to a superficial resemblance
in the crowns of the molars, as there was very
probably an essential difference in the formation
of the hind limbs.

As we are absolutely without any clue to the
origin of Seals, we may here mention one other
circumstance which seems to speak in favour of
the great age of this side-branch of the primary
Carnivora. What we yet know of the change of
teeth in Seals shows that the change takes place at
an extraordinarily early stage of life.1 In most
cases the change takes place before birth ; the milk-
teeth never come to be of any use whatever, and the
permanent teeth are cut when the young animal is
but a few weeks old, and while making its first
feeble efforts to join its parents in their repasts.
Fig. 51 shows the teeth of a probably still unborn
Greenland seal (Phoca gronlandica). The shading
shows the limit of the gums. It will be seen
that the milk-teeth have already vanished, all but

a few unimportant remains; d ^ have wholly

1 J. Steenstrup, ' Maelkestandsaettet hos Eemmesaelen,'
Naturhistorick Foreningens Vidensk. Hcddeleser. 1880.

290

THE MAMMALIA.

disappeared, the first and only permanent molar
of the lower jaw has already cut the gum.

Teeth of the same kind as these milk-teeth,
which are wholly without any significance to the
individual as functional organs, but of the highest
interest for the history of the group, we became
acquainted with when discussing the Whales (p. 247).

FIG. 51.— Foetal Teeth of a Greenland Seal.

The embryonal teeth of the Whalebone whales — even
though there were no Dolphins or Sperm whales-
are an irrefutable proof that the Whalebone whales
are descended from toothed animals. In the same
way the case before us shows, that the milk-teeth
of Seals which have in our day become of utter

THE SEALS. 291

insignificance to the organism, were of actual
service to their ancestors, just as the deciduous
teeth of most of our present mammals are of use for
several years. None of these milk-teeth have the
prospect of being preserved like the one remaining
deciduous tooth of the Marsupials (p. 94) ; accord-
ingly the Seals of future periods will undoubtedly
not show a trace of milk-teeth.

The Seals belong to the physically weaker groups
of mammals, and it is certainly most remarkable,
and as yet not explicable, that the other mammals
also, which have already been discussed, and are
allied to the Seals as regards the suppression of the
change of teeth, belong, on the whole, to the less
favoured or less strongly developed orders. For,
as we have repeatedly remarked, the main feature
that runs through the whole world of mammals is
the concentration of strength upon a shortened
jaw, at the cost of the disappearance of teeth. This
is most evident in the case of true Carnivora, where,
however, the milk-teeth still play an important part.

10. THE INSECTIVOEA, OB INSECT-EATERS. RODENTIA,

OR RODENTS. CHEIROPTERA, OR BATS.

Of these three orders the Insect-eaters have
already been mentioned from time to time. They

292 THE MAMMALIA.

existed in very early times, and had, at the begin-
ning of the Tertiary, already attained a stage of
development which has been transmitted to the
present members of the group, with but trifling
modifications ; and it is probable that a transi-
tion into hoofed and carnivorous animals had
shown signs of incoming as early as the so-called
Mesozoic period. The question as to why all the
group did not join in the transformation is as
obvious as the answer to all similar questions : that
the special conditions of life for these animals
must have existed uninterruptedly, and that, in
addition, they possessed a great amount of adap-
tability. Thus we find the order of Insect-eaters-
which is represented in Central Europe only by
the hedgehog, mole, and shrew, but more numer-
ously in other parts — in many ways similarly
adapted to the most varied conditions of existence
as the Kodents. In fact, their variability, even in
primeval times, explains the fact of their having
been able to adapt themselves to entirely new
organisations, and Huxley specially traces to them
the hoofed and carnivorous animals.

The same remarks apply to the Rodents, except
that in all of the periods known to us through
fossils, they were far more numerously represented.

INSECT-EATERS, RODENTS, AND BATS. 293

The Eoclent type is likewise found perfected at the
beginning of the Tertiary period. It may be said
that it was then less specialised, that most of the
Rodents of those days were more carnivorous than
the majority of our day, or, at least, more omni-
vorous ; however, little is to be gained from this for
our present enquiry.

The dentition of the Eodents appears to be
prepared, and almost perfectly attained, by the
Marsupials ; l and thus in following their tracks
we are again referred to the Jura period, and even
further back, where the separation of an already
developed mammalian fauna had taken place : into
Marsupials (as the main group), Eodents, and
Insect-eaters.

The latter order, no doubt, gave rise to the Bats,
which have fluttered about in their present shape
since the Eocene period. Two of our most common

1 A comparison of the very different shapes of the molars in
the Rodents among one another, and the approximation of many
of the genera — not as yet decided Rodents — to the Rodent type
(for instance, the wombat, the fmgered-animal, and rock coney)
renders it extremely probable that even our present Rodents are
not of one and the same origin. ' The fact remains, animals of
different derivation have attained a similar exterior, succeed
extremely well in the struggle for existence, or even better in
their endeavour to obtain food. Unlike as they may be, in one
point they are incontestably alike, i.e. in the development of
continuously growing incisors.' — BAUME.

294 THE MAMMALIA.

genera, Vesi^ertilio and Rhinolophus, were contem-
poraries of the PalseotheridaB and the Cynodictis of
South-western France. As regards their origin we
can only confess our ignorance on the subject, even
though we can perfectly well imagine the transfor-
mation of a climbing insect-eater into a flying one.
The elongation of the fingers of the fore limb, and
the expansion of the flying membrane to the hind
limbs, took place in those early periods from which,
as far as our knowledge of the Mammalia is con-
cerned, only a few dim rays of light have found
their way to us.

11. THE PROSIMIJE, SEMI- APES. SIMI^, APES.

THE MAN OF THE FUTURE.

The opinion of zoologists of the Linnaean school,
and those belonging to the first half of our century,
that the whole class of Semi- apes were, in fact, half
apes has generally been abandoned ; the opinion
was based upon the occurrence of hands on the fore
and hind limbs, upon the formation of the face, and
upon the peculiar dentition, which in most cases
shows no gaps. The more recent theory does not ex-
clude the supposition that among the very differently
formed genera of so-called Semi-apes, one or other
species might claim a closer relationship with the

SEMI-APES AND APES. 295

Apes, but neither the result of any anatomical or
palaeontological investigation allows us to draw
even a plausible inference of any such probability.

As there are only a small number of genera of
Semi-apes, and these are confined to Madagascar
(Africa and Southern Asia possess only a few aber-
rant members of the group), we had to conclude
that they are but the remnant of a group. Their
dentition and brain point to thelnsectivora, of whose
morphological capacities we have had such important
instances in the course of our discourse.

A true semi-ape — and, as regards skull and
dentition, a lemur of our day — was discovered by
Filhol among the varied accumulation of mammals
in the phosphate of Quercy, and was named Ne-
crolemur antiquus. By its side there lived several
species of a genus already discovered by Cuvier, the
Adapis, an animal whose dentition points to a re-
lationship with the Pig-shaped tribe, but still may
have been a creature of arboreal habits. Another
animal has had its position assigned to it by the
name of Cebochcerus, i.e. Hog-ape, owing to its
very characteristic molars, the crowns of which
show four tubercles. America has also furnished
its contingent to this group, which combines the
characteristics of the thick-skinned animals with

296 THE MAMMALIA.

those of semi-apes, a combination which has not
shown much capacity for resistance or of adapta-
bility to new conditions of life.

That forms of this kind gave rise to the Apes has
been conjectured by different palaeontologists and
also by Gaudry. The Apes found in the Miocene
of the Old World belong already partly to the still-
existing group — we dare not say family — and have
been called ' Anthropomorphse ' (man-like apes)
owing to various peculiarities in different genera.
If we hold by the present arrangement of the
order, and agree to the opinion — based upon facts
that have never seriously been doubted, and are
founded upon substantial reasons in the history of
the individual development as well as of anatomy —
that the apes of to-day form a kindred unity, other
considerations will present themselves. It is true
that lowest species of South American apes, the
clawed apes, have thirty-two teeth like those of the
Eastern hemisphere, but the form of these teeth and
the structure of the hands and feet point to a
decidedly close proximity with the Insectivora.
Further, they are allied to the Apes of the New
World by the fact that they do not, like the Apes
of the Old World, possess two, but show three
premolars. And all the other American apes show

SEMI-APES AND APES. 297

n n K £

cheek-teeth, not -^. Even the earliest
6 — 6 5 — 5

Miocene apes of Europe and Asia show a reduction
in the dentition, hence the American apes stand
nearer to the primary forms. Further, the genera
with six cheek-teeth, it seems to us, point more
probably to ancestors of the Insectivorous species
than to the Pachyderma. It is, therefore, not
only possible, but has come to seem probable, that
our present apes, in regard to their descent, have
met from two entirely distinct origins : the American
group from the Insectivora, the Europe- Asiatic line,
with the Anthropomorphge, from ancestors of the
Pachydermata species.

This would lead up to the question as to whether
our own ancestors belonged to the thick-skinned
group. But the very title of our book withholds us
from entering upon this subject, and we are all
the more justified in postponing any such discussion,
as the study of anthropology can in no way boast
of having made any definite progress during the
last ten years.1

1 The relation between the Anthropomorphoid Apes and Man
has been admirably discussed by Hartmann, ' Die mensch-
ahnlichen Affen.,' Internat. wissenschaft. Bibliothek, 60 Bd.
Leipzig, 1883. For further accounts of this subject we would
refer the reader to Schlosser and Seler, Die ersten Menschen und
27

298 THE MAMMALIA.

However, we may be permitted to cast a glance
at the future. Our discussion has repeatedly
proved that any advance in the animal groups was
connected with a reduction of the jaw or of the
limhs. It would seem that any reduction in the
fingers or toes of the human hand or foot would be
neither desirable nor advantageous in any way;
moreover no such loss is to be feared, although it
may be, as Darwin says, that baldness is in prospect
for men of the English race. It is a different
matter as regards our dentition, and we are not
so certain of its continuing in its present state,
although the human race would seem to have com-
menced with it as it is, and found it sufficient for
the most varied conditions of existence. But never-
theless a few gentle warnings seem to shake the
belief in this supposed unalterable stability.

The alternative as to whether Man was created
or developed can no longer be raised, now that we
are exercising the free use of our reason. Man's
dentition has to be judged from our experiences
made in the mammalian group. Hence, first of
all, it is a reduced dentition. True, we do not
know the definite stages by which it was attained

die prahistorischen Zeiten. According to a work of the same
name by the Marquis de Nardaillac. Stuttgart, 1884.

SEMI- APES AND APES. 299

in Man, any more than we do in the case of the
Anthropomorphoids and all the other Apes of the
Old World, but we shall not hesitate to maintain
that the ancestors of Man possessed a fuller number
of teeth, as long as deductions are justified from the
observation of facts. Our teeth have decreased in
number during the course of our geologico-zoolo-
gical development ; we have lost on either side,
above and below, two incisors, two premolars, and
one molar. By this we transfer ourselves back to
those periods from which the jaw of the Otocyon
has been preserved (see p. 267). Baume, our
eminent odontologist, in a recent work which we
have repeatedly referred to, has successfully fol-
lowed and pointed out cases of atavism or reversion
in the human jaw, by tracing cases of ' surplus '
teeth — and certain dental formations met with in
the jaws in a large percentage of cases — back to
those portions of the jaw in the animal ancestors
of Man which have disappeared in the course
of ages.

If, in former times, more teeth were met with in
the group which was perfecting itself into Man, we
must be permitted to ask — nay, we are compelled in
a purely scientific spirit to ask — whether things
have come to a standstill in this part of our

300 THE MAMMALIA.

organisation, or whether a further reduction is to
be anticipated ? Man is certainly one of the so-
called * persistent species,' but he is not uncon-
ditionally stationary. He varies as regards
dentition. Imperfect as are our statistics on this
point, this much is certain, that the cases of dis-
appearance or loss of teeth most frequently concern
the so-called wisdom teeth and then the outer
incisors. We do not of course know how often the
question has applied to the actual and complete loss
of the teeth, or only to some interference with the
teeth cutting the gum, occasioned by a limitation
of the necessary space. However, it must be re-
membered that the shortening of the jaw stands in
direct correlation with the reduction of the den-
tition. A prediction of the Man of the Future is
given us by Cope : the lower races of men will

2 1
retain the dentition of the present day, i -, c -,

O Q

p ~, m -, while the intellectually higher races
2 o

will be distinguished by the dental formulas :

. 1 123

1 V C1'P* m 3

• , . I 1 2 Z
and i ~, c j, p -, m ~.

THE MAN OF THE FUTURE. 301

We agree with this in so far that, as a rule, the
reduction of the dentition — where the disappearance
does not affect the whole set of teeth — can he brought
into connection with the idea of progress, and many
proofs of this have been given in the course of our
discussion. Still this higher faculty of resistance
and of acquiring food is not necessarily accom-
panied by an increase in the power of the adapta-
bility and a perfecting of the intellectual faculties.
In the Cat we have a more powerful, and hence a
higher development of the nature of the rapacious
animal than in the Dog, with its more old-fashioned
form of dentition. Yet who would think of placing
Cats as intellectually higher than Dogs ? It is
the same with the prospects of the human races.
Modifications in the human dentition are sure to
take place, as surely as man cannot rid himself of
his animal ancestors, even though they may be felt
to be inconvenient. But progress in the intellectual
and moral domain — and here our well-founded
idealism steps in — is not dependent upon the
possession or the loss of our wisdom teeth. The
correlation is not wanting, but it makes itself felt
in an opposite direction. The man who is engaged
in making inventions and in scientific pursuits, and
is advancing and encouraging all the nobler and

302 THE MAMMALIA.

more refined enjoyments of life, is not improving
the instruments for the acquisition of his food ;
they deteriorate in his hands — a condition which
first began to make its appearance with the inven-
tion of cooking. The reduction of the human
dentition — which has been of advantage to the
species in its struggle for existence — has further
increased and changed to a kind of atavism or
reversion, since reason, acquired with speech, has
made Man more and more independent of the direct
effects of his natural surroundings.

Hence it is not merely from a purely zoological
point of view that an inference is formed regarding
the future change of the human race. Moreover,
we cherish the hope — which is justified by scientific
experiences — and the belief, which rests upon the
same foundation, and these convince us of the
sure advance of humanity, and of the gradual and
general diffusion of morality, culture, and well-
being among the various races of Man.

INDEX

ACTS
ACERATHERIUM, 81, 190, 195

Adapis, 295

^Elurogale, 277

Amblyctonidse, 283

Amphibos, 178

Amynodon, 1

Anchitherium, 79, 190, 203,

210

Ancodus, 170
Ancylotherium, 126
Animals, Crescent-toothed, 137

- Odd-hoofed, 189

— Ohio, 233

- Pair-hoofed, 137
Anoa, 179

Anoplotherium, 80, 129
Ant-bears, 124
Antelope arabica, 176
Antelopes, 79, 173

— Saiga, 76

Anthracothermm, 80, 142
Anthropomorphae, 297
Antilocapra, 161
Appenzell, cattle of, 179
Arctocyon, 80, 282, 285
Arctocyonidas, 283

Arno, Val d' (Pliocene), 79
Auchenia, 157

CAI

BABIRUSSA, 138

Balaena, 250

Baltavar (Upper Miocene), 79

Bear, 280

Bearded Whale, 247

Bear-dog, 280

Bern cattle, 179

Bettongia, 100

Bibos, 178

Bibovina, 178

Bison, 178, 179, 187

Boar, wild, 138

Bos, 176, 178

Bradypus, 114

Bramatherium, 172

Brontotherium, 81, 199

Bronze-dog, 264

Bubalina, 178

Buffalo, 186

Buffelus, 178

Bull-dog, 264

Bunodonta, 137

Bunotheria, 284

CADICONA Lignite (Lower Mio-
cene), 79
Cainotherium, 79, 182

304

INDEX

CAM

Camargue, house of, 221
Camels, 154
Camelus, 157
Canidae, 259
Canis, 259

— antarcticus, 262

— anthus, 262

— argentatus, 262

- azarae, 262, 268

— cancrivorus, 262

- fulvus, 262

- latrans, 262

- littoralis, 262

- lupaster, 264
— * lupus, 264

- magellanicus, 262

- pallipes, 264

— suessi, 265

- vulpes, 260

— zerda, 262

Cattle of Appenzell, 379

- 173, 178

- Dutch, 179

- of Bern, 179

— Short-headed, 189

- Tyrolese, 189
Cats, 275

Cave Wolf, 265
Central German Horse, 224
Cervulus, 161
Cervus canadensis, 163
Cetotherium, 251
Chalicotherium, 201
Chelys fimbriata, 37
Chlamydophorus, 120
Cho3ropotamus, 142
Chcerotherium, 142
Choloepus, 149
Colonoceras, 81
Coryphodon, 80, 81, 132, 284

DUO

Creodonta, 282, 283, 284
Crescentic-toothed animals,

137

Ctenacodon, 100,
Cynodictis, 271
Cyon, 266

DASYPUS, 120

Dasyurus, 269

Debruge, Lignite (Upper

Eocene), 79
Deer, 79

— Eed, 162

— Rein, 165

— Telemetacarpal, 163
Diceratherium, 81
Dichobune, 80
Dicotyles, 138, 141
Dicrocerus, 79, 161
Didelphia, 93
Didelphys, 97, 99
Diluvial Horse, 224
Dingo, 262
Dinoceras, 81, 241
Dinocerata, 240
Dinotherium, 79, 236
Diphyodonta, 43
Diplopus, 170
Diprotodon, 103, 104
Diptacodon, 81

Dogs, races of, 259

— Bear- dog, 280

— Bronze-dog, 264

— Bull-dog, 264

— Viverrine dog, 271

— wild dogs of Africa, 264
Dolphins, 248
Dorcatherium, 79
Dremotherium, 79

Duck Mole, 86

INDEX

805

DTJT

Dutch cattle,179
Dwarf musk deer, 167

ECHIDNA, 86

Egerkingen (Middle Eocene),

80

Eibiswald (Middle Miocene), 79
Elasmotherium, 190, 197
Elephants, 79, 228, 235
Elk, 165

Entelodon, 80, 282
Eohippus, 81, 190, 213
Eohyus, 143
Eppelsheim (Upper Miocene),

79

Equus caballus, 218
• — stenonis, 216
Eutheria, 93

FELTS, 276

Fingered animal, 293

Fontainebleau, sand (of the

Lower Miocene), 79
Fox, 260
Frontosus race, 179

GELOCUS, 79, 164, 170

Georgsmiinde (Middle Eocene),
79

Gerard-le-Puy, St. (Lower Mio-
cene), 79

Giraffe, 170

Girdled animals, 120

Glossotherium, 124

Glyptodon, 123, 124

Greenland seal, 290

Giinzberg (Middle Eocene), 79

JER

HALICORE, 242
Halitherium, 242
Hampshire (Upper Eocene), 79
Hatteria, 28
Helaletes, 81, 193
Helladotherium, 79, 172
Helohyus, 143
Hipparion, 79, 190, 203
Hippopotamus, 144, 145, 140,

203
Hog-deer, 138

- wart, 138

Hollow-horned animals, 173
Horse, 190, 201

Diluvial, 224

— occidental, 223

— of the Camargue, 221

— of Solutre, 220

— oriental races of, 223

- wolf-toothed, 210
Hyaemoschus, 167, 168
Hyaena, 79, 280
Hvamarctos, 280
Hyamodon, 80, 282
Hydaspitherium, 172
Hydropotes, 163
Hyopotamus, 168
Hyrachyus, 81, 193
Hyracodon, 81
Hyracotherium, 80
Hyrax, 241

ICTICYON, 266
Ictitherium, 79, 280
Insectivora, 284, 286

JACKAL, 264
Jerboa, 76

306

INDEX

LAP

LA FERE, Sandstcin (Lower

Eocene), 80
Lama, 155
Leberon (Upper Miocene),

79

Leptobos, 178
Lignite of Cassino (Pliocene),

79
London clay (Lower Eocene),

80
Lophiodon, 190, 192

PITA.

MACHAIRODUS, 276
Macrauchima, 228
Macrotherium, 125
Mammoth, 235
Manatus, 242
Mastodon, 79, 231
Mauremont (Middle Eocene),

80

Megatherium, 81, 114
Mesodonta, 284
Mesohippus, 81
Mesonychidse, 283
Metatheria, 93
Miacidse, 283
Microlestes, 98
Miohippus, 81
Monodelphia, 93
Monophyndota, 43
Montabuzard (Middle Eocene)

79

Montpellier, marl of, 79
Moropus, 125
Muntjak, 161
Musk deer, 167
Mylodon, 114

NECROLEMUR, 295
Neoplagiaulax, 100
Norwich crag, 79
Nototheriurn, 104

OCCIDENTAL HORSE, 223
Odd-hoofed animals, 189
Oenigen (Upper Miocene), 79
Ohio animals, 233
Oreodon, 81
Oriental races of the horse,

223
Orleans, sand of (Middle

Miocene), 79
Ornithorhyncha, 86
Orohippus, 81, 190
Otocyon, 268
Oxyama, 81, 283, 285
Oxyrenidse, 283

PAIR-HOOFED ANIMALS, 137

Palaeochcerus, 142

Palaeocyon, 282

Palseonictis, 80

Palseoprionodon, 274

PaL-eotherium, 80, 190, 201

Palorchestes, 104

Parameryx, 156

Paris gypsum (Upper Eocene),
79

Paris coarse limestone (Up-
per Eocene), 80

Pea ore (Middle Eocene), 80

Peccary, 130, 140

Perchcerus, 143

Phacochcerus, 138

Phascolomys, 104

INDEX

307

PHA

Phascolotherium, 99
Pigs, 70, 137, 141
Pikermi (Upper Miocene), 79
Plagiaulax, 99, 100
Plesictis, 274

Plesiometacarpal deer, 1G3
Pliauchenia, 157
Pliohippus, 81, 190, 215
Pliolophus, 80
Pcebrotherium, 159
Poodle, 264
Portacina, 178
Primigenius bos, 179
Proaelurus, 275
Probubalus, 178, 179
Procamelus, 156
Procervulus, ICO
Prorastomus, 244
Protohippus, 81, 190, 214
Protolabos, 156
Prototheria, 93
Prox, 160
Pseudaslurus, 275
Pterodon, 80, 282

QUERCY PHOSPHOEITE (Upper
Eocene), 79

RED DEER, 162

Rein deer, 165

Rhinoceros, 79, 81, 190, 194

• — minutus, 198

Rhinolophus, 294

Rhytina, 243

River horse, 144

Ronzon, lime rocks of (Lower

Miocene), 79
Ruminants, 150

TiTK

SABRE-TOOTHED TIGER, 277

Saiga antelope, 76

Sand of Orleans (Middle Eo-
cene), 79

Sansan (Middle Miocene), 79

Selenodonta, 137

Short-headed cattle, 189

Shorthorn bull, 175

Simocyon, 79

Sivalik hills (Upper Miocene),
79

Sivatherium, 172

Sloth, giant, 113

Smooth whale, 250

Soissonnais, lignite of (Lower
Eocene), 80

Solutre, horses of, 220

Squalodon, 251

Stegodon, 234

Stenoplesictis, 274

Strata, tertiary, of N. America,
81

T^NIODONTA, 284

Tapir, 79, 189, 190
Tapiravus, 81, 193
Taurina, 178
Telemetacarpal deer, 163
Tertiary strata of N. America,

81

Thylacinus, 269
Thylacoleo, 102
Tillodonta, 284
Tillotherium, 81, 286
Tinohyus, 143
Toothed whales, 247
Tragulid®, 167
Trichechus, 287
Tyrolese cattle, 189

308

INDEX

T7110

UlttWASTlX, 28

Ursus, 280

VAL D'AKNO (Pliocene), 79
Vcspertilio, 294
Vienna basin, 79
Viverraj, 274
Viverrine dog, 271

WALRUS, 287
Wapiti, 163
Wart-hog, 138
Whales, toothed, 247
— bearded, 247

ZETT

Wild boar, 138

Wild dog of Africa, 2G4

Wolf, 2G5

— Indian, 264

Wolf-tooth of horse, 210

Wombat, 104, 293

XJPHODON, 182
Xiphodontheiiurn, 182

YAK, 179

ZEDGLODON, 251