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“KNOWLEDGE” SERIES.

LIFE AND ROCK:

a COLLECTION OF ZOOLOGICAL AND
GEOLOGICAL ESSAYS.

\

By R. LYDEKKER, B.A. Cantab, F.GS., F.ZS,

AUTHOR OF ‘‘ PHASES OF ANIMAL LIFE” AND ‘‘ HORNS AND HOOFS”’3
JOINT- AUTHOR OF ‘‘THE STUDY OF MAMMALS” AND
‘( ’ MANUAL OF PALAONTOLOGY”; EDITOR AND
CHIEF AUTHOR OF ‘‘THE ROYAL NATURAL
HISTORY,” ETC., ETC.

NUMMULITE.

London:
TITE UNIVERSAL PRESS, 326, HIGIT HOLBORN, W.C.

1894.

A

PREFACE.

In presenting to the public the following series of essays,
which have already appeared in serial form, the Author
has but few words to say by way of preface.

It will be seen from the chapters themselves that the
greater portion of the work relates to Zoology—and
especially its paleontological branch—while only a small
section is devoted to Geology proper.

While some of the zoological chapters treat of the
natural history of particular groups or species of
animals, others are more especially devoted to some of
those problems connected with the evolution, development,
and mutual relationships of animals which at the present
day are attracting so much attention on the part of
students of the science.

Although necessarily somewhat technical in places, the
Author hopes that the popular style, which he has
‘endeavoured to preserve throughout the work, will render
it acceptable to those lovers of Nature who are too often
repelled by the number of hard words they meet with in

the books professedly written for their edification.

HARPENDEN,

March, 1894.

XII.
XIII.
XIV.

XV
XVI

XVII.
XVIII.
XIX.

XX.
XXII.

CONTENTS.

Elephants, Recent and Extinct
Tusks and their Uses

Moles and their Like

Spiny Animals

Parallelism in Development

Toothed Whales and their Ancestry

Whalebone and Whalebone Whales
Runinants and their Distribution
The Tallest Mammal

Lemurs

Armadillos and Aard-Varks

The Oldest Mammals

Crocodiles and Alligators

The Oldest Fishes and their Fins
Living Fossils

The Extinction of Animals
Protective Resemblance in Animus
Sea-Urchins

Nummulites and Mountains

A Lump of Chalk and its Lessons
A Flake of Flint and its IJIistory

LIST OF ILLUSTRATIONS.

African Elephant
Skeleton of Mammoth
Foot of Elephant

Tooth of Mastodon
Indian Elephant .

Teeth of Elephants
Skeleton of Mastodon
Tusks of Babirusa
Narwhal

Skull of Chinese Water-Decr
Skull and Tusk of Uintathere
Cape Golden Mole
Long-clawed Mole-Vole .
Marsupial Mole .
Common Porcupine
Hedgehog

Spiny Anteater

Foot of dArtionyx

Skull of Protoceras
Bridled Dolphin

Teeth of Killer

Indian Porpoise .

Pacific Black-Fish

LIST OF ILLUSTRATIONS.

Section of Skull of Greenland Whale
Skeleton of Extinct Irish Deer
Cheek Tooth of Antelope

Bones of Foot of Ruminant

Horns of Gazelle

Skull of Sivathere

Antlers of Red and Sambar Deer
Giraffe

Slender Loris

Tarsier

Three-banded Armadillo
Pichiciago

Six-banded Armadillo

Ethiopian Aard-Vark

Jaw of Stonesfield Mammal

Jaw of American Jurassie Mammal
Jaw of Triconodon

Jaw of Plagiaulax

Jaws and Teeth of Rat-Kangaroo
Skull of South African Secondary Mamunal
Side view of Skull of Crocodile
Skull of Crocodile

Skull of Extinet Crocodilian

The Bichir

An Extinct Ganoid

Skeleton of Perch .

Skeleton of Fin of Extinct Shark
Skeleton of Extinct Shark

Tooth of Extinct Lung-Fish

LIST OF ILLUSTRATIONS,

Shell of Pleurotomaria

A Pentacrinid

Skeleton of Northern Sea-Cow
Leaf Butterfly

Test of Common Sea-Urchin
Test of Secondary Sea-Urchin
Test of Paleozoic Sea- Urchin
Test of Cretaceous Heart-Urelun
A Nunmulite

Flint Implement

Cone of Flint

xi

PAGE,

154
158
168
178
186
189
190
191
197
210

212

LIFE AND ROCK:

A COLLECTION OF ZOOLOGICAL AND
GEOLOGICAL ESSAYS

CHAPTER I.
ELEPHANTS, RECENT AND EXTINCT.

SSUREDLY of all the mammals now inhabiting this
A earth elephants are those most justly entitled to the
epithet “antediluvian,” since they remind us, far more
vividly than any of their modern contemporaries, of the
gigantic extinct mammals of various kinds which flourished
in that latest epoch of geological history when man was but
a comparatively new comer. A long acquaintance has,
indeed, made us so familiar with the appearance of
elephants that we are too apt to forget what altogether
strange and uncouth creatures they really are. If, however,
they had happened to be included among those animals
which disappeared from the face of the earth before the
historic period, and were known to us solely by their
skeletons, there can be no doubt that they would be
regarded as among the most remarkable of mammals.
Moreover, if elephants were only known to us by their
skeletons it would be more than doubtful if we should ever
have attained a correct idea of their true form; since
although the conformation of their jaws and teeth would
clearly indicate that they must have had some very peculiar
method of feeding, yet it would have required a very bold,
not to say a very imaginative man to have conceived the
idea that these creatures were furnished with that unique
organ which we term the trunk or proboscis.

At the present day, it need scarcely be said, there are
but two living species of elephants, differing remarkably
from one another not only in external characters, but
also, as we shall notice later on, in the structure of their

B

2 ELEPHANTS, RECENT AND EXTINCT.

teeth; these two species being respectively confined to
Africa, and to India and the adjacent regions. These two
kinds of elephants are, however, merely the last survivors
of a vast host of extinct forms, some of which were closely
related to their living cousins; while others differed so
markedly in the structure of their teeth as to have
received the distinctive appellation of mastodons, although

lephant.

Dj

1.—Young African I]

Fia.

MASTODONS. 3

Fre. 2.—Skeleton of Mammoth in the St. Petersburg Museum.

they are really nothing but very generalized elephants,

These so-called mastodons carry us backwards to the

middle portion of that_division of the Tertiary period of
B2

A ELEPHANTS, RECENT AND EXTINCT.

the earth’s history known as the Miocene; but when we
have reached to that stage all below is dark as regards the
elephantine pedigree. And it is, indeed, one of the most
remarkable circumstances in paleontology that although
we know that elephants belong to the great group of
Hoofed or Ungulate Mammals, of which they form a
well-marked division, yet we have practically no sort of
knowledge of the many extinct forms which we presume
must have connected them with Ungulates of a more
ordinary type.

Although the trunk and tusks of elephants form their
most striking external features, yet it is not to these that
the naturalist looks at first when inquiring into the true
affinities and general structure of these animals, since
these come under the category of specialized and acquired
structures, which tell but little of an animal’s past history;
he looks rather to the structure of the internal skeleton,
which is always of especial value, as being that part of the
organism which is usually alone preserved ina fossil state.
Let us then first turn our attention to the skeleton of these
animals, of which we may see examples in our larger
museums. The most remarkable feature noticeable in such a
skeleton is that the various long-bones of the limbs are
placed almost directly one above another, so as to form
nearly vertical columns of support for the body ; whereas in
ordinary Ungulates, such as a horse or an ox, these bones
are set very obliquely to one another. Moreover, as a
similar vertical position of the limb-bones occurs in several
old extinct Ungulates which are known to be of extremely
primitive organization, we may take it that an elephant’s
limbs are likewise of a primitive type. We have, however,
further evidence in confirmation of this primitive structure.
Thus elephants differ from all other living Ungulates in
having five complete toes to all their feet (Fig. 3).
Moreover, whereas in other living Ungulates (except the
little hyrax) the bones of the wrist are not situated in
vertical rows immediately over the metacarpal bones of
the foot, but, on the contrary, cross and overlap one
another, in elephants they have the former relation, with
the single exception that the bone marked 1 overlaps the

STRUCTURE OF FEET. 5

one lettered td to a certain extent. This difference may
be illustrated by saying that if we were to take a hatchet
and chop vertically up-
wards between the third
and fourth toes of an
elephant’s foot there
would be nothing to resist
the passage of the blade
till it reached the bones
of the leg, whereas in all
other living Ungulates, iy

except the hyrax—the pig oS

for instance — the blade
could not pass through
the wrist without cleaving
solid bone. Again, where-
as ordinary Ungulates Fie. 3.—Bones of the Left Fore Foot
walk solely on the tips of of an Elephant, one-eighth natural
their toes, and are thus size. The lettered bones are those

«tgs : f the wrist or carpus, an
termed digitigrade, while aioe ones the ae
the bones of the toes them- }elow which are the bones of the
selves are more or less toes. (After Osborn.)
elongated, elephants walk
on the soles of their feet im the so-called plantigrade
fashion, and have very short toe-bones. Now, since
all the large extinct Ungulates of the lower Eocene,
or earliest Tertiary period, also have five-toed feet,
very similar to, but still shorter and of even simpler
structure than those of elephants, there can be no
doubt as to the extremely primitive plan on which the
entire limbs of the latter are constructed. As regards,
therefore, its limbs and feet, an elephant may be said to
be an essentially old-fashioned animal.

If, however, we turn to their teeth we shall find that
elephants are very far indeed from being of a primitive or
old-fashioned type; the truth being that they are, on the
contrary, very peculiar and specialized in this respect.
The first and most obvious peculiarity in regard to their
dentition is to be found in their tusks, which correspond
to one of the pairs of upper front teeth in man, and

6 ELEPHANTS, RECENT AND EXTINCT.

also to the single pair of such teeth in the Rodents
(rats, hares, &c.). Moreover, these teeth, like the incisors
of the Rodents, grow continuously throughout the life
of the animal,
owing to the cir-
cumstance that
the pulp-cavity
at their base
always remains
open, and has a
permanent con-
nection with the
soft structures
of the gum. In
our own teeth,
on the contrary,
the pulp-cavity
closes at a cer-
tain period, after
which there is a
total cessation of
growth. These
ever-growing
tusks of the
elephants are
preceded in the
young animal by
a pair of small
milk-tusks, with
a closed pulp-
cavity, which are
shed at an early
period of life.
In both of the
living species of
elephant the
tusks are con-
fined to the
upper jaw; but whereas they occur in both sexes in the
African elephant, in the Indian species large permanent

aS

Fia. 4.—Last or Sixth Upper Molar Tooth of
a Mastodon; half natural size.

TUSKS AND MOLARS. 7

tusks are restricted as a rule to the male, and are not,
indeed, invariably present in all individuals of that sex.
In the female Indian elephant the tusks are usually very
small, and soon shed. The primitive elephants, or masto-
dons, frequently, however, had tusks in both the upper
and lower jaws; and since these did not generally attain
the huge dimensions which they reach in many true
elephants, it is evident that in this respect the mastodons
departed less from the ordinary type of mammals, where
the front teeth are not greatly larger than the hinder ones,
and those of the upper and lower jaws correspond with
one another in size and number. Before leaving the
subject of tusks, it may be mentioned that the ivory of
which they are composed differs from the so-called ivory
of other teeth in a manner which renders it always easy
to determine whether a reputed ivory article is genuine.
This peculiarity consists in the circumstance that a trans-
verse section of a tusk exhibits a series of fine, decussating,
curved lines radiating from the centre to the circumference,
and forming curvilinear lozenges at their intersections.
This remarkable structure is in fact precisely similar to
the “engine-turning”’ on the back of a watch; and in an
ivory knife-handle it should be distinctly visible at the
butt.

We turn now to the grinding or molar teeth, which
present far more remarkable peculiarities. So peculiar,
indeed, and unique are the structure and mode of suc-
cession of the molar teeth of elephants, that they are often
very imperfectly understood, even by those who have spent
half their lives among these animals. For instance, we
find the late veteran elephant-hunter, Sir 8. Baker, in his
“Wild Beasts and their Ways,” making a statement in
regard to elephants that ‘“ both the Indian and the African
varieties have only four teeth,” whereas, as a matter of
fact, every elephant has, in the course of its life, six
molars on each side of both the upper and lower jaws.
Instead, however, of all these teeth being in use at one
and the same time, as are those of a cow or ahorse, in
existing elephants there are never more than portions of
two teeth in use at any one time, although, in the extinct

8 ELEPHANTS, RECENT AND EXTINCT.

mastodons, portions of three may co-exist. In all
elephants, the more anterior of these six teeth are smaller
and of simpler structure than the hinder ones, and the

whole series is protruded in an are of a circle from back
to front, the larger hind teeth being pushed up and
gradually coming into use as the small anterior ones are

Fie. 5.—The Indian Elephant.

MOLAR TEETH. 9

worn away and finally discarded. The hinder ones of
these teeth (Fig. 6) are so large that while the front
portion is being worn away, the back is still bedded in the
gum. In the earlier elephants, or mastodons, these molar
teeth are composed of a series of relatively low and widely
separated transverse.ridges, more or less completely divided
into inner and outer moieties, and with large open valleys
between them. Moreover, in all the teeth, except the last,
these ridges do not exceed four in number, although in
the sixth tooth (Fig. 4) there may be as many as five or
six. Such a molar tooth can be easily derived from the
ordinary type of tooth presented by the molars of the pig,
in which the crown carries four columns, severally placed
at its corners. When a tooth like the one represented in
Fig. 4 becomes worn down by use, the enamel coating each
of the columns would be cut through, so as to expose a
series of more or less trefoil-shaped surfaces of ivory,
each surrounded by a ring of the hard enamel. And it
will be obvious that a tooth thus constructed of alternations
of substances of different degrees of hardness would act
as an efficient millstone. Elephants do not appear,
however, to have been by any means satisfied with this
comparatively simple kind of tooth, for as we pass upwards
in the geological scale we find that there has been a gradual
increasing complexity in the structure of the molar teeth
of these animals, this being due to a graduated increase
in the height of their transverse ridges, accompanied
by an increase in the number of the ridges themselves.
There is, indeed, an almost perfect structural gradation,
now known to exist between the mastodon tooth, repre-
sented in Fig. 4, to the teeth of true elephants shown in
Fig. 6. Both the latter examples are in a somewhat worn
condition, but it will be readily seen that the lozenge-
shaped surfaces of ivory, surrounded by enamel, in the
tooth of the African elephant, correspond to the transverse
ridges of the mastodon’s tooth. In the true elephants,
however, the open valleys between these ridges (which
have now assumed the form of tall, thin, and nearly
parallel laminz) have been completely filled up by a third
constituent of the tooth, known as the cement. The

10 ELEPHANTS, RECENT AND EXTINCT.

grinding surface of the tooth of such an elephant con-
sequently consists of a solid mass, made up of alternating
vertical transverse layers of various substances, arranged

Fic. 6.—Molar Teeth of Indian (a) and African (4) Elephant.
In athe anterior half is worn, and the remainder unworn.
Much reduced. (After Owen.)

in the order of cement, enamel, ivory, enamel, cement;
and since each of these constituents differs in hardness, it
will be obvious that the millstone-like apparatus is now of
a far more efficient type than it was in the mastodon.
Moreover, since the crowns of the molars of the true
elephants are very much taller than are those of the
mastodons, it is evident that they will require a longer
period of time before they become worn away, and that
they will therefore allow a longer life to their owner.
Tiven, however, among true elephants there is a con-
siderable amount of difference in regard to the number
and narrowness of the component plates of their molar
teeth, and it will be seen from Fig. 6 that in this respect
the African elephant departs far less widely from the
mastodon than does its Indian cousin. Since the food of

EVOLUTION. 11

the latter consists to a large extent of boughs and twigs,
while that of the former is composed more of juicy leaves,
fruits, and roots, the necessity of a more complicated
masticating apparatus in the one than in the other is
apparent.

In modern elephants, the six molar teeth on either side
of each jaw are all that are ever developed. This is,
however, by no means the case with some of the earlier
elephants, and with most of the mastodons. In these
animals, when the second and third molars became worn
out, they were succeeded vertically by much smaller teeth,
from which we learn that the first three molars of the
modern elephants really correspond to the milk-teeth of
other mammals, which, as we all know, are succeeded
vertically by some of the teeth of the permanent series.
This succession of the teeth shows us, therefore, another
point in which mastodons tend to connect modern
elephants with ordinary Ungulates.

We might go further and enter upon the consideration
of some of the structural peculiarities presented by the
soft parts of elephants. Enough has, however, been
stated to show that while these animals have preserved
a very ancient type of structure in their limbs, they
have acquired a very special modification in the structure
and mode of succession of their teeth. And it is highly
probable that it is owing to this particular specialization
that elephants have survived to our own day, while all
the other plantigrade and five-toed primitive Ungulates
have completely passed away; while it is almost certam
that it is this feature alone which has enabled them to
attain the gigantic bulk which forms one of their most
striking features. In regard to their evolution, perhaps
no group shows more clearly than that of the elephants
how exceedingly important is the study of fossils to eluci-
date the relations of existing animals. Had we only the
two living species of elephants to deal with, we should
never have had the least mkling of the manner in which
they were related to other Ungulates, imperfect as our
knowledge of the relationship still is. Moreover, from
the distribution of these two species, it would have been

12 ELEPHANTS, RECENT AND EXTINCT.

naturally inferred that elephants were creatures suited
solely to tropical or sub-tropical climates. The discovery
of frozen carcases of the mammoth—a species closely
related to the Indian elephant—in the Siberian “tundras”’
shows, however, that this animal was suited to dwell in at
least comparatively cold regions, although it is probable
that the climate of Siberia was formerly not so rigorous
as at present. To withstand the cold of these northern
regions, the mammoth was protected by a coat of long
reddish hair, beneath which was a shorter covering par-
taking more of the nature of wool. Along the borders
of the Arctic Ocean for hundreds of miles mammoth
remains are met with in incredible quantities ; and it is
still one of the puzzles of geology to account adequately
and satisfactorily for the manner in which these creatures
perished, and how their bodies were buried beneath the
frozen soil before decomposition had begun its work, for
it is hardly possible to believe that they lived in a climate
so rigorous that their bodies would have been frozen on
the surface of the ground immediately after death.

Another rude shock to our common ideas of elephantine
nature is afforded by the extinct elephants of Malta,
which show us that gigantic size is not a necessary
concomitant of the group; and that when the area in
which a species dwelt was small, the size of the species
itself was proportionately reduced. These little Maltese
elephants were very closely allied to the livmg African
species, but whereas “Jumbo’’ attained eleven feet in
height, and wild specimens of the African elephant may
be still larger, the smallest of the Maltese species was
scarcely taller than a donkey. So small, indeed, are the
bones and teeth of this species exhibited in the Natural
History Museum, that it is sometimes difficult to convince
people that they really belong to elephants at all.

As regards their distribution, elephants and mastodons
formerly roamed over the whole world with the exception
of Australia; true elephants ranging over the whole of
the Northern Hemisphere, while mastodons extended as
far south in the New World as the confines of Patagonia.
It isin the north-east of India, Burma, and the islands of

DISTRIBUTION. 13.

the Malayan region that the fossil elephants connecting
the living species with the mastodons are alone found ;
and it is thus probable that from these regions the true
elephants migrated westward into Europe and Africa,
while the mammoth in later times crossed from Asia into
Alaska by way of Behring Strait. That the mammoth,
which ranged from the Arctic regions to the Alps and
Pyrenees, was a contemporary of the primeval hunters of
Europe is now a well-established fact, but it appears that
throughout the Old World mastodons had utterly died
out before the advent of man. In the New World,
however, the continuity between the old and the new
fauna was more fully sustained, the Missouri mastodon
having survived well into the human period, so that we
have in this survival a good instance of the vast changes
that have taken place in the fauna of the globe within
what we may metaphorically call the memory of man,

14 TUSKS AND THEIR USES.

CHAPTER II.

TUSKS AND THEIR USES.

Many mammals, such as the elephant, hippopotamus, and
walrus, are furnished with one or two pairs of pointed
conical or compressed teeth largely exceeding all the
others in length, and to which the term “tusks” is usually
applied. Lions and wolves likewise have two pairs of
somewhat similarly enlarged teeth in the fore part of their
jaws; and although these are proportionately smaller than
in the animals above named, it will be obvious that in
popular language it is difficult not to include them under
the same general title. Using, then, the term “tusks”
for all such enlarged simple teeth, it may be of interest to
note the groups in which these attain their greatest
development, and also endeavour to learn something
regarding their uses. An especial interest attaches,
indeed, to the subject, on account of the extreme beauty
of many of these teeth, and also from the circumstance
that it is these alone which yield the various descriptions
of ivory.

In a great number of instances such tusks comprise a
pair in both the upper and lower jaws, which are situated
immediately behind the front, or incisor teeth, and,
from their marked development in the dog tribe, are
scientifically designated canine teeth; the name “eye-
teeth” being also not unfrequently applied to them in
popular language. Tusks of this sort are characterized
by the circumstance that the lower one on each side bites
in front of the upper one ; while the latter is always the
first tooth situated in the true upper jaw-bone, the incisors,
or front teeth, heimg implanted in a more anteriorly
situated bone known as the pre-maxilla. In any ordinary

NATURE OF TUSKS. 15

carnivorous mammal, such as a lion or a wolf, the upper
tusks are considerably larger than the lower, although
neither project beyond the edges of the muzzle when the
jaws are closed. If we examine such tusks in a dried
skull we shall find that their roots (which, as in all tusks,

Fie. 7.—Skeleton of Missouri Mastodon.

are simple) are completely closed ; thus indicating that
their growth ceased at a certain period of life. Moreover,
we may notice that the upper and lower pairs of tusks do
not abrade against one another to any marked extent, and
that consequently their summits are only subject to the
ordinary wear and tear necessarily undergone during use.
In many other mammals the form and structure of these
tusks is, however, very different. Take, for instance, a
wild boar, in which the upper tusks are short and curved

16 TUSKS AND THEIR USES.

upwards, while the larger and more slender lower pair
abrade against their outer surfaces, and are thus worn to
sharp, cutting edges. Obviously such tusks, if they were
incapable of growth like those of the lion, would soon be
worn away to mere stumps and become useless to their
owners. To prevent this, the bases of the tusks remain
permanently open (as shown in Fig. 10), and contain a soft
pulp connected with the vascular structures of the jaw, in
consequence of which the teeth continue to grow through-
out life; their rate of growth thus keeping pace with that
of the abrasion to which they are subject. Tusks may
accordingly be divided into two classes, which we may
designate hollow and solid. The open tusks referred to
above are prevented from attaining any very great length
by the abrasion of the lower against the upper pair, but in
other cases, as in those of the remarkable pig of Celebes
known as the babirusa (Fig. 8), no such abrasion takes
place, and both pairs then attain enormous dimensions,
projecting in this particular instance far above the upper
surface of the head, and the down-curving points of the
upper pair sometimes even penetrating the skull. A
babirusa may in fact be compared to a wild boar in which
one pair of tusks having been broken, the other cont‘nues
to grow without any abrasion by wear; only that in these
animals both pairs are thus developed. In the wild boar
and its allies the tusks—more especially those of the
1ower jaw—are purely offensive and defensive weapons ;
but it is hard indeed to imagine the use of those of the
babirusa. Probably Mr. Wallace is right in regarding
them as an ultra-development of organs originally useful,
but which have now, from some reason or another, become
of no functional advantage to their owner, and have thus,
so to speak, run riot.

The babirusa presents us with an instance of a mammal
in which both pairs of tusks have acquired their enormous
development owing to the cessation of the mutual attri-
tion between those of the upper and lower jaws, character-
izing all its allies. On the other hand, in the mastodons
and elephants we have examples where the development
ig normal, and either one or both pairs attain a vast size.

TUSKS OF ELEPHANTS. 17

In both species of existing elephants, as in many of the
mastodons (Fig. 7), only the upper pair of tusks is thus
developed; but in other mastodons these organs were
present in both jaws, the upper pair being, however,
always much larger than the lower. In the pigs and
babirusa the tusks, of which the upper pair are implanted
in the true jaw-bone, correspond severally with those of

Fie. 8.—Fore part of Skull and Tusks of Babirusa.

the lion and the wolf, and are accordingly reckoned as
canines. This, however, is not the case with those of the
elephants and mastodons, which grow in great part from
the pre-maxillary bone, and thus correspond with one
pair of the front or incisor teeth of other mammals.
Consequently, much as they resemble them in general
appearance, the tusks of an elephant are not homologous
with those of a pig or a babirusa. As we have entered

Cc

18 TUSKS AND THEIR USES,

in some detail into the structure of the tusks of tke
elephants in the previous chapter, it will be unnecessary
to recapitulate the facts here; although we may mention
that in modern elephants these organs consist wholly of
ivory, without any investing coat of enamel. The tusks
of these animals, which belong to the hollow type, are the
largest developments of dental structure to be met with
in the whole animal kingdom. To a great extent they are
weapons of defence and offence, but in the African species,
where they are common to both sexes, they are also largely
used in grubbing up roots and overturning trees ; while
in an extinct species from India their length is so great
that they must have quite ceased to be useful, and were
probably an actual encumbrance. Another allied extinct
animal, known as the dinothere, is unique in having a
large pair of downwardly-bent tusks in the lower jaw and
none in the upper; the use of these being very difficult to
conjecture.

A still more remarkable condition obtains in the
hippopotamus, in which not only are the canine teeth
developed into an enormous pair of hollow, ever-growing
curved tusks in each jaw, but the central pair of lower
front or incisor teeth are so enlarged as likewise to merit
the title of tusks. These incisor-tusks—which thus cor-
respond to the lower pair of the four-tusked mastodons—
are hkewise of permanent growth, and project forwards
from the front of the jaw in the form of two elongated
cones. In thus possessing three pairs of tusks the
hippopotamus is quite peculiar among animals. Largely
employed for tearing up the erasses, on which these
monsters feed, the tusks of the hippopotami are also most
effectual offensive weapons.

In the land carnivores, of which more anon, the tusks
are always of the closed type; but in their aquatic ally,
the walrus, we again meet with a huge pair of ever-
growing tusks directed downward from the upper jaw.
On comparing the head of a walrus with that of au
elephant, most persons would say at once that the tusks
of the two animals were homologous. In this, however,
they would be wrong, since, as we learn from the con-

TUSK OF NARWHAL. 19

dition in the young animal, those of the walrus are true
canines, whereas, as we have seen, the tusks of the
elephant are incisors. We have here, therefore, a well-
marked instance of the parallel development of severally
dissimilar structures to attain a marked general simi-
larity. The tusks of the walrus, which in old animals
attain a great length, are mainly employed in digging
up molluses and crustaceans from the sand and shingle,
and also, it is said, to enable their owners to clamber up
on the ice.

Although the whalebone-whales are entirely deficient in
teeth, and many of the dolphins and their allies have these
organs but poorly developed, there are two cetaceans
which exhibit a most remarkable development of tusks.
The first of these creatures is the well-known narwhal,
of the Arctic seas, in which, as a rule, there is one huge
spirally-twisted cylindrical tusk projecting from the left
side of the upper jaw of the male, which continues to grow
throughout life. Whether this solitary tusk is a canine
or an incisor, is not very easy to determine ; but it is

Fie. 9.—The Narwhal. (After True.)

remarkable that its fellow of the opposite side generally
remains concealed in the jaw-bone, like the kernel of a nut
in its shell, while in the female both teeth are thus rudi-
mentary. Occasionally, however, male narwhals are met
with in which both the right and left tusks are developed ;
and it is somewhat curious that in such cases the direction
of the spiral in the two tusks is the same, instead of being,
as in the horns of antelopes, opposite. Although narwhals
have never been known to charge and pierce ships with
their tusks, after the manner ‘of sword-fish, it is still
uncertain whether these formidable weapons ( which may
attain a length of from eight to nine feet) are normally
c2

20 TUSKS AND THEIR USES.

used for purposes of attack, or for procuring food.
Doubtless, however, the narwhal’s tusk is of some use to
its owner; but in another cetacean, known as Layuard’s
mesoplodon, the tusks appear not only useless, but actually
harmful. In the whale in question, which is a rare species
from the southern seas, there is but one large strap-like
tusk on each side of thie. middle of the lower jaw, both of
these curving upwards and inwards over the snout, so as
actually to prevent the mouth from opening to its full
extent. The only possible use we could suggest of such a
structure would be to prevent the creature dislocating its
jaw by yawning; but as other animals manage to get on
without such an arrangement, this is scarcely likely to be
a solution of the problem. It is more probable, indeed,
that we have here to do with another instance of ultra, or
monstrous development.

Other examples of hollow or permanently-growing tusks
occur among the hoofed mam-
mals, other than the pigs, in all
of which these teeth are found
only in the upper jaw, and are
developed chiefly or solely in
the males. Among recent forms
these tusks attain their greatest
development in the little musk-
deer of the Himalaya, where
they are frequently over three
inches in length, and project
considerably below the lower
Fie. 10.—Extremity of the jaw. In form they are sabre-

Skull of a young Chinese like, and recall the upper tusks

Water-Deer, withthe base of the feline carnivores, only

o ie ces being more slender, and grow-

ae “ine permanently. Similar but
smaller tusks are met with in the Chinese water-deer
(Fig. 10), in the Indian muntjac, and the little deer-like
animals known as chevrotains. The latter belonging
to a totally distinct group from the others, it is
evident that these scimitar-like tusks have been inde-
pendently acquired in the two groups; while it is quite

TUSKS OF UINTATHERES. 21

probable that those of the musk-deer and Chinese water-
deer are likewise of separate origin. With the exception of
the muntjac, in which they are very small, all these deer-
like animals are devoid of antlers; and it is thus evident
that their tusks have been developed in lieu of those
weapons. It is true, indeed, that the males of some of
the antlered deer have small tusks, but these are of no
use for offensive purposes, and are evidently organs in
process of degeneration. Moreover, in the hollow-horned
ruminants, such as oxen and antelopes, where the horns
are permanent and generally present in both sexes, not a
vestige of tusks remains.

Although the Asiatic rhinoceroses have procumbent
tusks of considerable size in the lower jaw, none of the
odd-toed hoofed mammals, such as horses and tapirs,
have upper tusks of any size. In past times there were,
however, in North America a group of somewhat allied
creatures known as uintatheres, in which an enormous
pair of upper tusks, somewhat like those of the musk-deer,
was developed (Fig. 11). Like those of the latter, these
tusks grew permanently, and they were also protected by
a descending flange of the lower jaw, which was often
deeper than in the figured example. As these animals had
front teeth only in the lower jaw, we have here, therefore,
another curious instance of the parallel development of
similar conditions in totally unconnected groups. What
use these creatures could have made of their tusks is,
however, not very clear, as in the living condition they
could have projected but little below the lower jaw, while
they were too long to have been effectual when the mouth
was open. These uintatheres were also noteworthy on
account of having a number of bony projections on the top
of the skull, which in life may have been sheathed in horn;
and it is not a little remarkable that another extinct
creature—Protoceras (Fig. 19)—belonging to the even-toed
eroup of hoofed mammals had a skull with very similar
bony projections and also similar upper tusks.

Our last instance of animals furnished with per-
manently-growing upper tusks is afforded by the reptilian
class, in which the extinct South African creatures

22 TUSKS AND THEIR USES.

described many years ago by Sir R. Owen, under the
name of Dicynodon, are thus armed. In these reptiles,
some of which attained gigantic dimensions, the jaws were
mainly sheathed in horn like those of a turtle ; the single
pair of tusks curving down-
wards and forwards from
near the middle of the upper
one. Possibly these tusks
were capable of being em-
ployed when the mouth was
open like those of lions or
tigers; but otherwise it is
difficult to see their use.
Certain allied reptiles from
the aforesaid formations,
known as anomodonts,
had a full series of teeth,
with a large pain of tusks
in the upper jaw, which
may or may not have been
rooted, but are exceedingly
f like those of certain car-
Fre. 11.—Extremity of the Skull Mivores. As these reptiles
and Tusk of a Uintathere. are not the direct ancestors
of mammals, we have
thus evidence of the acquisition of tusks in two distinct
classes.

As regards solid tusks, or those in which the lower end
is closed at a certain period coincident with the cessation
of growth, almost the only mammals, save the rhinoceroses
(where, as we have seen, there may be a forwardly-directed
pair in the lower jaw) and some of the marsupials, in
which they attain any marked development are the carni-
vores. Among these, the maximum size of tusks at the
present day is attained in the larger felines, such as the
lion, tiger, and leopard. In these animals the tusks are,
however, never so much elongated as to bar the front of
the open mouth; while very frequently their tearing
power is increased by the hinder cutting-edge being
finely serrated. Their terrible effect in tearmg and

GENERAL CONCLUSIONS. 23

rending the animals upon which these fearsome carnivores
prey is too well known to need further mention. During
the Tertiary period there existed certain carnivores nearly
allied to the modern cats, but exhibiting a much greater
development of the upper pair of tusks, with a corre-
sponding reduction of those of the lower jaw. In these
creatures, which are known as macherodonts, or sabre-
toothed tigers, the upper tusks were greatly compressed
and flattened, with serrations on one or both cutting-edges;
their length in a species of the approximate size of a tiger
being upwards of seven inches. As in the uintatheres,
the anterior end of the lower jaw had a descending flange
to protect the end of the tusk. Manifestly, such enormous
weapons would completely bar the sides of the open
mouth, and consequently they could not be used in the
manner of the tusks of a lion or tiger. It is still more
difficult to imagine that these animals could have struck
with their tusks projecting from below the closed mouth ;
and it would consequently seem that in this instance also
the tusks attained a development which was harmful
rather than advantageous—this conclusion being confirmed
by the fact, for what it is worth, that the sabre-toothed
tigers have become totally extinct, while their less
specialized allies continue to flourish.

Finally, as regards tusks in general, it appears that
while in the land carnivores these are always canines, are
present in both jaws, and have closed roots, in the other
orders of mammals their development is apparently some-
what capricious, while they are very frequently present in
only one jaw—almost invariably the upper—and continue
to grow permanently. Moreover, they are almost as
frequently incisors as they are canines; so that tusks
apparently similar may be in nowise homologous with one
another. Never developed to any size in animals with
large cranial appendages in the form of antlers or horns,
tusks are frequently wanting in those lacking the latter.
Primitively their use was undoubtedly as weapons of
attack and defence, or to aid in procuring vegetable food ;
but in many cases they have subsequently undergone a
(frequently sexual) development beyond the needs of such

24 TUSKS AND THEIR USES.

purposes, and are thus in this respect analogous to the
antlers of many stags. In other instances, however—and
this in all the groups in which they occur—they have
undergone a still further semi-monstrous development,
rendering them if not actually harmful, probably in some
cases inconvenient to their owners. Lastly, the independent
acquisition in closely allied or widely separated groups of
mammals of tusks of very similar structure and appearance,
shows how little reliance is to be placed on external
characters as indicative of relationship.

MOLES AND THEIR LIKE, 25

CHAPTER III.
MOLES AND THEIR LIKE.

Iv is probably well known to most of our readers that in
the evolution of organized nature two great factors have
constantly been working against each other—the one being
the adherence to a particular type of structure, while the
other is the adaptation to a special mode of life. The
usual resultant of these two forces has been that, in any
assemblage of animals specially adapted for a certain
peculiar kind of existence, while internally its different
members have preserved their essential structural
peculiarities more or less intact, externally they have
become so much like one another that it often requires
the aid of the professed zoologist to point out their
essential distinctness. Perhaps in no case is this adaptive
similarity in external characters better displayed than
among certain of the smaller mammals which have taken
to a more or less completely subterranean burrowing
existence, of which the common mole is the best known
example. In the British Islands we have, indeed, only
this one creature which has adopted this particular mode
of life; and it is to this animal alone that the name
“mole” properly belongs. Other parts of the world
possess, however, several more or less closely allied animals
to which the same name must clearly be also applied. If,
however, we happen to have friends from the Cape, we
may hear them applying the name “moles” to certain
burrowing mammals from that district, which upon exami-
nation would be found to differ essentially in structure
both from the ordinary moles and from one another.
Then, again, if we were to travelin Afghanistan or some
of the neighbouring regions, we should meet with another
mole-like burrowing animal to which we should likewise
feel disposed to apply the same name, although it has not

26 MOLES AND THEIR LIKE.

the most remote kinship with our English mole. Finally,
the deserts of central South Australia are the dwelling-
place of the “marsupial mole,” which, although mole-like
in general form, differs from all the animals yet mentioned
in belonging to the marsupial order.

We thus arrive at the conclusion that in the popular
sense the term “mole” now serves to indicate a number
of widely different animals, whose sole or chief bond of
union is to be found in their adaptation to a similar mode
of life, and their consequent assumption of a more or less
similar outward form. Hence, in order to avoid confusion,
it will be necessary to prefix the epithet ‘“‘true”’ to those
species which belong to the same family group as the
“little gentleman in black velvet,” while the remainder
must be designated by other distinctive epithets. It might
have been thought that such an expanded application of
the name “mole’’ was restricted to popular language.
This, however, is not the case, as naturalists have found it
convenient to adopt the names “ sand-mole,” ‘ golden
mole,” “marsupial mole,” etc., as the distinctive titles of
different members of this purely artificial assemblage of
animals; and the reader will accordingly understand that
when we speak of “moles and their like,” we merely
refer to a similarity in habits, and a more or less marked
external resemblance between the animals under consider-
ation.

The general bodily form of the common mole is so
thoroughly well known and familiar, that the term “ mole-
like”? has been introduced into zoological, if not into
popular, literature as a definite descriptive epithet. Since
it is perfectly obvious that this peculiar form is the one
best adapted for the needs of the creature’s subterranean
existence, no explanation is necessary why most of the
other members of the assemblage have conformed more or
less closely to the same type. We may especially notice
the flat, tapering, and sharp-nosed head, passing backwards
without any distinctly defined neck into the long and
cylindrical body ; the comparative shortness of the limbs,
and the immense strength of the front pair, which are
placed close to the head, and have their feet expanded into

TRUE MOLES. 27

broad, shovel-like organs. We shall also uot fail to
observe the absence of any external conchs to the ears,
and the rudimentary condition of the deeply-buried
eyes. A long tail would also be useless to a burrowing
animal, and we accordingly find this appendage reduced to
very small dimensions ; while the close velvety hair is
most admirably adapted to prevent any adhesion of earthy
particles during the mole’s subterranean journeys. Equally
well-marked adaptive peculiarities would also present
themselves were we to undertake an examination of the
mole’s skeleton. While the majority of the assemblage
conform more or less closely to the true moles in appear-
ance, there are others in which such resemblance is but
slightly marked, if apparent at all, from which we may
probably infer some minor differences in their mode of life.

Proceeding to the consideration of the different groups
of mole-like animals, it will be convenient to divide the
mixed assemblage into insectivorous moles, rodent moles,
and marsupial moles. The term “insectivorous moles,” it
may be premised, does not primarily indicate carnivorous
habits in the species thus designated, but merely refers to
the fact that they are members of the order Insectivora.
It would of course be impossible, not to say out of place,
to attempt a definition of that order ; but it may be men-
tioned that it includes small mammals, like shrews, moles,
and hedgehogs, which differ from the rodents in not pos-
sessing a pair of chisel-like teeth in the front of the jaws,
and also have their molar teeth surmounted by a number
of small sharp cusps.

The insectivorous moles include not only our common
mole (Talpa europea), but also many other species belong-
ing to the same genus, as well as certain others which are
referred to distinct genera, all of which, for our present
purpose, may be collectively spoken of as true moles. Of
these, two genera (Talpa and Scaptonyx) inhabit Europe
and Asia, while the other three are North American ;
Africa having no representative of the group. It may be
well to mention that all the true moles have very broad
naked hands, each furnished with five toes carrying lone
flattened nails, in addition to which there is a sickle-like

28 MOLES AND THEIR LIKE.

extra bone internally to the thumb. In burrowing, most
of them throw up the well-known molehills at certain
intervals from the tunnels driven in search of worms—
their chief food.

In addition to these trae moles, North America also
possesses certain other species known as shrew-moles,
which, while belonging to the same family (Zalpide), are
distinguished by the absence of the sickle-like bone in the
hand and the less expanded form of the bones of the upper
part of the fore-limb. They are thus clearly seen to be
less specialized creatures than our own mole, to which
they closely approximate in general appearance.

Although belonging to the insectivorous order, the mole-
like creature represented in the accompanying figure
indicates a totally different family group. If we were to
examine the upper molar teeth of a common mole, we
should find that they had broad crowns, carrying cusps
arranged somewhat after the manner of the letter W. On
the other hand, in the Cape golden mole (as the animal

Fie. 12.—The Cape Golden Mole.

here represented is termed) the corresponding teeth have
triangular crowns carrying three cusps arranged in a V.

f=)

RODENT-MOLES. 99

Moreover, if we look at the fore-limb, we find instead of
the five-fingered hand of the mole that there are but four
digits, of which the lateral pair are small, while the two
middle ones are enlarged and furnished with triangular
claws of great power. As in the true moles, all external
traces of ears and eyes are concealed by the fur; this
latter, it may be added, having a peculiar golden-green
metallic lustre, from which the name of the animal is
derived. The golden moles, of which there are several
species, are much smaller than our English mole, and are
widely distributed in South Africa ; in which continent
they, in conjunction with the under-mentioned sand-mole
and its allies, take the place occupied in the northern
hemisphere by the true moles. In tunnelling, the golden
moles come so close to the surface as to leave a ridge
marking their course. The true moles and the golden
moles aftord us, therefore, an instance of two entirely
distinct groups belonging to the same order having
assumed a perfectly similar mode of life, and, con-
sequently, having acquired a superficial general similarity
in external appearance.

With the rodent-moles, of which there is likewise more
than a single group, we come to animals of a totally
different order, which have assumed a mole-like form aud
habits, and are popularly confounded with the true moles.
In common with the other members of the order Rodentia,
all these rodent-moles are characterized by the presence
of a pair of powerful chisel-like incisor teeth in the front
of each jaw, while their molars have broad and flattened
crowns adapted for grinding. Moreover, instead of driving
their tunnels in search of worms, these rodent-moles
burrow for roots and bulbs. All of them have very small
or rudimentary ears and eyes, large and powerful claws,
and short tails.

One of the best known of these rodent-moles is the great
mole-rat (Spalax), ranging from south-eastern Europe
to Persia and Egypt, in which the eyes are completely
covered with skin; allied to which are the bamboo-rats
(Rhizomys) of north-eastern Africa and Asia, distinguished
by having minute uncovered eyes and small naked ear-

30 MOLES AND THEIR LIKE.

conchs, and thus departing more widely from the mole type.
In the ‘sandy soil of Eeypt the mole-rat constructs tunnels
of great length in search of bulbs. In South Africa these
forms are replac ‘ed by the huge sand-mole (Bathyergus),
which attains a length of about ten inches; and also by
certain smaller animals known as Georychus and Myose alops ;
differing from the former by the absence of grooves in
their incisor teeth. The sand-mole is commonly met with
in the flats near the shore, while the smaller forms
generally frequent land at a higher elevation. Sometimes,
lowever, both are found together, and the country is then
covered in all directions with hillocks precisely resembling
those made by our English mole. Although the sand-mole
has uncovered eyes, these are not bigger than the heads
of large pins, and can have but little visual power. Still,
however, their presence serves to indicate that these
animals have not become so completely adapted to a
subterranean life as is the common mole, and this is
confirmed by the fact that if their burrows are opened,
the sand-moles after a few minutes usually protrude their
noses from the aperture with a view to discover the cause
of the disturbance, whereas an ordinary mole would under
similar circumstances remain below.

All the foregoing belong to one family of rodents; but
in addition to these certain members of the vole group
(a sub-division of the Wuridw) have also taken to a subter-
ranean burrowing life, with the assumption of a mole-like
hodily form. These may be termed mole-voles, and range
from Russia to central and northern Asia, where they are
represented by the two genera Hllobius and Siphneus. ‘They
all have mole-like heads and bodies, short limbs and tails,
rudimental external ears, very minute eyes, and powerful
fore-paws. In the Russian mole-vole (Ellobins) and the
allied Quetta mole from Afghanistan the claws of the front
paws are short; but, as shown in our figure, they become
oreatly elongated in the members of the genus Siphneus.
All of ‘bean agree with the ordinary Peg in the peculiar
structure of shale molar teeth, which consist of a number
of triangular prisms placed edge to edee; and all are
described as driving subterranean tunnels and throwing

RODENT-MOLES, 31

out at intervals heaps of earth precisely after the fashion
of the common mole.

The foregoing are the only rodents which have assumed
amore or less distinctly marked mole-hke external form
while retaining all the characteristic structural features of

Fie. 13.—The Long-clawed Mole- Vole.

the order to which they belong. There are, however, two
other members of the same great order which, while having
acquired mole-like habits, have not assumed a distinctly
mole-like form. One of these is the tuco-tuco (Ctenomys)
of South America, belonging to the same great family as
the capivara and the coipu. This animal is rather
smaller than a rat, with a relatively shorter tail, pale grey
fur, and red incisor teeth. Its general form is also not
unlike that of a rat, the limbs being of fair length, and the
front paws not markedly enlarged, while the eves are of
considerable size. The external conchs of the ears have,
however, been greatly diminished in size. The tuco-tuco
derives its name from its voice, which resounds day and
night from its subterranean dwellings, and is compared by
Mr. W. H. Hudson to the blows of u hammer on an anvil.

32 MOLES AND THEIR LIKE.

It frequents loose and sandy soil, although occasionally
found in moist heavy mould, through which it pierces its
way as readily as the mole. Darwin, who states that the
tuco-tuco is even more subterranean in its habits than the
mole, was told by the Argentines that blind examples were
often captured. This, however, is not the experience of
Mr. Hudson, who lays stress on the relatively large size
of the creature’s eyes. From the soft nature of the soil in
which it tunnels, it is not difficult to understand why it has
been unnecessary for the tuco-tuco to assume a mole-like
bodily form; but the reason for the retention of fully-
developed eyes—which we should have thought exceedingly
prone to injury—is hard indeed to divine.

The other rodents with mole-like habits are two tiny
little creatures from the sandy districts of Somaliland,
locally known by the name of farumfer, and scientifically
as Heterocephalus. They are about the size of a mouse,
with large heads, moderately long tails, long powerful
fore-feet, no external ear-conchs, minute eyes, and the
whole skin naked, save for a few sparse bristly hairs.
About as ugly a creature as can well be conceived, the
farumfer, if clothed with a thick coat of fur, would be not
very unlike a rather long-tailed, long-limbed, and narrow-
handed mole. For tunnelling beneath the hot sand of
the Somali desert the naked skin of the farumfer is most
admirably adapted; and as the creature is allied to the
South African Georychus, it may be recarded as the member
of this group most specially adapted fora subterranean
existence. Mr. E. L. Phillips, who was the first to observe
these curious rodents in the living state, writes that they
threw up in certain districts groups of elevations in the
sand which may be compared to miniature volcanic craters.
When the animals are at work, the loose sand from their
tunnels is brought to the bottom of the crater and sent
with considerable force into the air with a succession of
rapid jerks, the rodents themselves remaining concealed
in the shelter of their burrows, from which they appear
never to venture forth.

The extensive assemblage of pouched or marsupial
mammals contains groups corresponding to several of

MARSUPIAL MOLE. 33

those of the placental or higher mammals. Thus, for
instance, the kangaroos in Australia play the same réle as
the deer and ruminants in other parts of the world, while
the Tasmanian wolf takes the place of the ordinary wolf,
the wombats act the part of the marmots, the phalangers
of squirrels, and the bandicoots of the civets and weasels.
Till recently, it was thought that the place of the moles
(whether insectivorous or rodent) was unoccupied in the
Antipodes, and that no marsupial had adapted itself to a
tunnelling subterranean existence. Within the last few
years it has, however, been discovered that the sandy
deserts of south Central Australia are inhabited by a small
burrowing creature belonging to the pouched group, which
has been fitly termed the marsupial mole (Notoryctes) ;

Fia. 14.—Under-surface of the Marsupial Mole, two-thirds
natural size. (After Stirling.)

and it is not a little remarkable that in general appearance
this tiny animal is even more mole-like than are some of
the above-mentioned burrowing rodents, thus showing how
all-powerful is adaptation to environment, and of how
little import is internal structure in modifying the external
form of an animal. The general mole-like appearance of
the Australian burrower will be apparent from the accom-
panying figure; the most striking mole-like features being
the elongated and depressed body passing imperceptibly
into the bead, the absence of external ear-conchs, the
rudimentary pin-like eyes, the small tail, and the short
limbs, of which the front pair are armed with claws of

D

34 MOLES AND THEIR LIKE.

great power. The marsupial mole stands alone, however,
in having the front of the muzzle protected by a leathery
shield ; while its short and blunt tail is also covered with
a peculiar naked leathery skin. In the fore limbs the
structure of the feet recalls the golden moles rather than
the true moles, the third and fourth toes being greatly
enlarged at the expense of the others, and furnished with
huge triangular claws of enormous digging power. In its
pale, sandy-coloured hair, with a more or less golden
tinge, the marsupial mole departs widely from our sable
European friend; but it must be remembered that the
difference in this respect is really not so great as it at first
sight appears, seeing that cream-coloured varieties of the
common mole are far from rare. In the Australian form
the pale coloration is doubtless adapted to harmonize with
the natural surroundings of its native desert, since it has
been ascertained that the creature makes its appearance
from time to time above ground. That the resemblance
of the marsupial to the golden mole in the structure of
the fore-paws is a purely adaptive one, there can be no
reasonable doubt; but whether the identical structural
conformation of the molar teeth of the two animals
indicates any real genetic affinity, or is merely inherited
from an old ancestral type which may have been common
to many groups, is far less easy to answer.

The marsupial mole, or ur-quamata, as it is termed by
the aborigines, inhabits a very limited area lying about a
thousand miles to the interior of Adelaide; and even there
appears to be of extreme rarity. According to observations
supplied to its describer, Dr. E. C. Stirling, the creature
is generally found buried in the sand under tussocks of the
so-called porcupine-grass (T'riodia), and its food appears to
consist of insects and larve. The animals appear only to
move about during warm, moist weather ; and as they are
extremely susceptible to cold, it is probable that they lie
in a more or less torpid condition during the winter
months, when the surface of the ground is often white with
frost. When on the move, the marsupial mole is said to
enter the sand obliquely, and to travel for a few feet or
yards beneath the surface, when it emerges, and after

CONCLUSIONS. 35

traversing a short distance above ground, once more
descends. As it seldom tunnels at a depth of more than
two or three inches below the surface, its course may often
be detected by a slight cracking or movement of the
surface as the tunnel proceeds. Both in this respect, and
in the nature of its food, the ur-quamata therefore exhibits
a further analogy with the golden mole. In burrowing,
the leathery shield of the head is said to be brought into
play as a borer in the soft sand.

As regards the advantages obtained by those mammals
which have taken to a burrowing subterranean existence,
it will be manifest that these are twofold. In the first
place, the creatures are secure from all foes, except those
which, like the weasel and the snake, are able to follow
them into their underground labyrinths ; while, secondly,
they tap a food-supply (whether animal or vegetable)
inaccessible to most other animals. In the case of the
mole at least, whose habitations are generally made in
comparatively hard ground, the life must be an incessant
round of labour; and to our thinking, at any rate, the
existence of all these burrowing creatures must be so dull
and monotonous as to leave no question as to whether it
is worth living.

36 SPINY ANIMALS.

CHAPTER IV.

SPINY ANIMALS.

In the preceding chapter it was shown how the adapta-
tion to the necessities of a particular mode of life has
produced a marked general external resemblance in certain
burrowing mammals belonging to several more or less
completely distinct groups. We now propose to point
out the resemblances existing between certain other
members of the same class of animals, owing to the
assumption of a protective coat of spines. Although
this resemblance is in some instances not so striking as
among the creatures noticed in that chapter, yet it is
quite sufficient to have obscured in popular estimation
the real affinities of some of the spine-bearing mammals,
as it is by no means uncommon to hear the hedgehog
spoken of as the ‘British porcupine,’ while certain
Madagascar spiny mammals are frequently alluded to as
hedgehogs, and the Australian echidna is commonly
alluded to as a porcupine. Moreover, the names “ sea-
urchins’’ and “sea-hedgehogs,”’ applied to animals
belonging to totally different classes, shows the important
estimation held by spines in popular zoology. It is almost
superfluous to add that the acquisition of the coat of spines
in all the mammals here alluded to is solely for the pur-
pose of protection : and how sufficient is this protection in
most cases, is evident to all who have seen how the
hedgehog, when rolled up, sets most dogs at defiance.
Still, however, this panoply is by no means invariably
proof against all attacks, as it appears to be well ascer-
tained that leopards and pumas will kill and eat porcupines
without the shghtest hesitation, and with a total disregard
of their formidable spines, which may be found sticking in
all parts of the bodies of the devourers. As we found to be
the case with the mole-like mammals, all the spiny
mammals belong to the lower orders of the class, their

THEIR VARIOUS KINDS. 37

several representatives being distributed among the in-
sectivores, rodents, and egg-laying groups, and the
majority pertaining to the two former of these. In fact,
in this respect an exact parallelism may be drawn between
the mole-like and the spiny mammals, each assemblage
having several representatives among the insectivores and
rodents, while the former has a solitary marsupial type,
and the latter two members among the egg-laying
mammals. Some of these spiny mammals, such as the
true porcupines and the echidnas, are burrowing creatures,

Fig. 15.—The Common Porcupine.*

and thus have a double means of defence against their
enemies ; others, however, like the hedgehog, rely on their
power of rolling themselves up into a ball, and thus pre-
senting a chevauz-de-frise on all sides. Some again, like
the tree-porcupines, are more or less completely arboreal
in their habits; and the whole of them, like the mole-like
mammals, indicate how urgent has been the need for the
lowly-organized rodents, insectivores, and egg-laying

* We are indebted to Messrs. F. Warne and Co. for the loan of
the three figures illustrating this chapter.

38 SPINY ANIMALS,

mammals to acquire some special means of protection in
order to be able to hold their own among the higher
forms. As our readers are doubtless aware, in mammals
spines are nothing more than specially modified hairs, and
in a poreupine the transition from a spine to an ordinary
hair can be easily seen. There are many rodents in which
a certain number of scattered spines are mingled with the
fur of the back, but our remarks will be confined in the
main to the forms in which the spines predominate suffi-
ciently to render them the most striking feature in the
external appearance of their possessors. ;
Commencing with the rodents, our first representatives
of the spiny mammals will be the true porcupines (Hystriz),
which are such well-known creatures as to require but
brief description. These animals conform, of course, to
the ordinary rodent type in having a single pair of large
chisel-like incisors in each jaw ; and their spines are most
developed on the middle line of the head and back,
the hinder part of the body, and on the short tail.
Whereas, however, those on the body are solid throughout
and pointed at each end, the spines at the extremity of
the short tail are in the form of hollow quills inserted by
narrow stalks. It is these hollow quills that make the
loud rattling sound heard when a poreupine is walking ;
and it appears to us not improbable that they may have
given rise to the old legend of the porcupine ejecting its
spines whev attacked, as such hollow quills might well
have been thought to be receptacles for the ordinary
spines. Although their owner is unable to voluntarily eject
the latter, their pointed bases render them easily detached,
and leopards which habitually feed on porcupines are
found to be actually bristling with their quills. In attack-
ing its foes, the porcupine rushes at them backwards, and
thus gives full effect to its weapons. All the members of
the typical genus are characterized by their large size,
short tails, and highly convex skulls, and are confined to
the warmer regions of the Old World. The brush-tailed
porcupines (Atherura) from West and Central Africa and
the Malayan region are, however, of much smaller size,
and also distinguished by their much longer tails, which

PORCUPINES AND SPINY MICE. 39

terminate in a brush of flattened spines, and are thus
evidently less specialized creatures.

America is tenanted by a group of porcupines easily
distinguished from their Old World cousins by having
the soles of their feet covered with rough tubercles, instead
of being perfectly smooth, and also by their comparatively
short spies being mingled with a number of long hairs,
by which they may be partially concealed. The Canada
porcupine (Hrethizon) ditters from all the other American
species in having a short stumpy tail, and also in its non-
arboreal habits ; its spines being almost hidden by the
hairs. In parts of North America these porcupines are so
abundant as to be a positive nuisance, and an enterprising
engineer, with true American “cuteness,” hit upon the
original idea of utilizing their bodies as fuel for his engine
—apparently with the most satistactory results. The
lighter-built tree-porcupines (Synetheres), which are mainly
characteristic of the southern half of the American conti-
nent, are easily distinguished by their long tails, which,
as in so many South American mammals, are prehensile.
These porcupines are thoroughly arboreal in their habits,
and it is therefore easy to understand why their spines
are so much shorter than those of their terrestrial Old
World cousins, who have to rely solely on these weapons
for their protection.

In addition to the members of the porcupine family,
there are several other groups of rodents which develop
a more or less complete coating of spines. Among the
most remarkable of these groups are the spiny mice
(Acomys) of Syria and Eastern Africa, one of which, when
it has its spines erected, is almost indistinguishable at the
first glance from a diminutive hedghog. The spiny rat
of Celebes (Echinothrix) is another member of the mouse
family having the fur thickly intermingled with spines.
In a third rodent family (Octodontide), nearly all the
members of which are South American, there is also a
genus (Hchinomys), taking its name from the number of
flattened spines mingled with the fur of the back charac-
terizing all its representatives. It will thus be obvious
that even in a single mammalian order we have several

40 SPINY ANIMALS.

instances where a protective coat of spines must have
been acquired quite independently. te

This independent origin is still more clearly indicated
when we come to the consideration of the hedgehog and its

Sr eer ar sce ea Nass

Fic. 16.—The Hedgehog.

allies, which bear precisely the same systematic relation-
ship to the poreupines as 1s presented by the true moles to
the mole-voles, as described in our last chapter. That is to
say, whereas the hedgehogs and true moles belong to the
insectivorous order, the porcupines and the mole-voles
are herbivorous rodents. In spite, then, of the general
similarity of appearance between a hedgehog and a porcu-
pine, or, still better, a spiny mouse, we shall find, as
already mentioned, that whereas the two latter have the
ordinary chisel-like rodent teeth, the former has several
narrow and somewhat irregularly-shaped teeth in the
front of the jaws, while its back teeth are crowned with
numerous sharp cusps, instead of having nearly smooth
grinding surfaces. Accordingly, from the purely systematic
point of view there is no justification for calling the

HEDGEHOGS. 41

common hedgehog the “ British porcupine”; but, on the
other hand, if we allow similarities in external appearance
to be our guide in nomenclature, there are just as good
grounds for applying the latter title to the hedgehog as
there are for giving the names of golden or Cape mole,
sand-mole, mole-vole, and marsupial mole to four of the
creatures noticed in the last chapter. Our ancestors, to
whom the hedgehog was commonly known as the “ urchin,”
went, however, a step further than this, and, from the
resemblance of its spine to those of the mammal, gave
the name of sea-urchin to the Hehinus, a title which has
stuck to it ever since. Systematic zoologists need not
then wax so wroth as we have known them do when the
name of “ British porcupine” is applied to the urchin,
seeing that the analogies of nomenclature are sufficient
to justify its use. As the sea-urchins come most dis-
tinctly under the title of spiny animals, it may be
mentioned here that, although the spines of the common
British species are net unlike those of the hedgehog, yet
their structure is totally different. Thus, whereas the
spines of the mammal are of a horny nature, those of
the invertebrate owe their solidity to the presence of
carbonate of lime, and always break with the characteristic
oblique fracture of the mineral calcite. Moreover,
whereas the spines of the hedgehog are implanted in its
skin, those of the sea-urchin are entirely external, being
movably attached by their hollow bases to knobs on the
surface of the shell or “test.” Whether our worthy
ancestors believed that the land and sca-urchins were
connected by ties similar to those which in their estimation
affiliated barnacle-geese to barnacles, or how the name
“urchin”? came also to indicate a child, we are quite
unaware.

In place of terminating in sharp points, by which they
are but loosely attached to the skin, like those of the por-
cupine, the spines of the hedgehog terminate interiorly in
small knobs, which are placed beneath the skin, and may
thus be compared to pins stuck through a piece of soft
leather. Beneath the skin lies a layer of muscle known
as the panniculus carnosus; and it is by the action of this

42, SPINY ANIMALS.

muscle on their heads that the spines are raised from a
recumbent to a vertical position when the creature rolls
itself up into a ball—an action of which all porcupines are
quite incapable. Not only does the hedgehog differ from
the porcupine in this respect, but it is likewise peculiar in
using its spines as a means of protection when throwing
itself down a vertical bank or precipice, and by this means
is able to accomplish a vertical descent of over a dozen
feet without the sightest harm. As regards the develop-
ment of its spiny armour, the hedgehog is perhaps the
most highly specialized of all the spiny mammals, in spite
of the inferior length of its spines as compared with those
of the porcupine. Hedgehogs are now represented by
about a score of species ranging over Europe, Africa, and
a considerable portion of Asia; while the existing genus
dates from the middle portion of the Miocene division of
the Tertiary period. That the spines characterizing the
existing forms have been independently developed within
the limits of the group is pretty conclusively indicated by
the close affinity of the hedgehogs to the long-tailed and
spineless Malayan insectivores known as gymnuras; fossil
types apparently indicating an almost complete transition
from the gymnuras to the hedgehogs. In case anyone
should suggest that the latter, and not the former, might
be the ancestral stock, it may be mentioned that while the
gymnuras have a generalized type of dentition and long
tails, the hedgehogs have the teeth much reduced in
number and specialized in character, and short tails.

In Madagascar the place of the hedgehogs is taken by
an entirely different group of insectivores known as the
tenrecs, all of which have a certain number of spines
mingled with the fur, at least in the young condition,
and some of which are so hedgehog-like in general
appearance that by the non-zoological observer they
would certainly be regarded as members of the Erinaceidee.
The tenrecs differ, however, from the hedgehogs pre-
cisely in the same manner as the golden moles differ
from the true moles. That is to say, whereas in
the latter the crowns of the upper molar teeth are
quadrangular, with their cusps arranged in a somewhat

TENRECS. 43.

W-like manner, in the former these teeth are triangular,
with their cusps arranged in a V. There are five
species of tenrecs, classed under three generic headings,
and all characterized by the absence or small size of the
tail. The largest, and at the same time the most generalized
of all, is the common tenrec (Centetes ecaudatus), which
attains a length of from twelve to sixteen inches, and is
characterized by the absence of a tail, by the rows of spines
on the back being shed in the adult state, and also by
certain peculiar features in the dentition which appear to
indicate relationship with the pouched mammals. The
spiny tenrecs ( Hemicentetes) are much smaller avimals, of
the size of moles,in which the longitudinal rows of spines
on the back are retained throughout life. They have the
same number of teeth as fully adult individuals of the
common tenrec; but whereas in the latter there are four
upper molars and two upper incisors, in the spiny tenrecs
there are three of each of these teeth. In the loss of the
last molar these tenrecs are evidently more specialized
than the common species, but the presence of the third
incisor shows that they are descended from a still more
generalized type. Lastly, we have the hedgehog-tenrecs
(Ericulus), in which the whole upper surface of the body,
as well as the short tail, is thickly beset with spines,
thus giving the hedgehog-like appearance from which the
creatures derive theirname. The dentition is more reduced
than in either of the upper groups, thus indicating the
greater specialization of the genus; although the presence
of a short tail indicates direct descent from a tailed
ancestor. Although it is quite clear that the three genera
of tenrecs are divergent branches from a common stock,
yet it is not impossible that they may indicate the
manner in which the complete coat of spines characterizing
the third group has been gradually evolved. Against this
view it may, however, be urged that if the common tenrec
indicated the first commencement of the spiny coat, it
would be more likely to find the spines in the adult rather
than in the young. Be this as it may, the wide difference
between the hedgehogs and the tenrecs, coupled with the
affinity of the former to the gymnuras, leaves no doubt

44 SPINY ANIMALS.

that the spines have been acquired independently in the
two groups.

As we found the last representative of the mole-like
animals among the pouched mammals, so we observe that
spiny animals are represented among the still lower egg-
laying mammals by the spiny anteaters, or echidnas, of

Australia and New Guinea. The two kinds of echidnas
differ, however, externally from all the spiny animals
hitherto mentioned in the production of the muzzle into a
long, toothless tubular beak; and their spines are short,
and in some cases largely concealed by the fur. Neither
of them have the power of rolling the body into a ball;
and, whereas the Australian echidna has five toes to each

EVOLUTION OF SPINES. 45

foot, in the Papuan species the number is generally reduced
to three. The wide structural differences separating the
egg-laying mammals from all other members of their class
render it almost unnecessary to observe that the spines
of the echidnas are an entirely independent development.
Like so many of the spined mammals, the echidnas have
extremely short tails and thick bodies, with the neck
indistinctly marked. We have thus decisive evidence
that a more or less complete coat of spiny armour has
been independently acquired in the following groups of
mammals, viz., in the porcupines, mice, and octodonts
among the rodents; in the hedgehogs and tenrecs among
the inmsectivores; and in the echidnas among the ege-
layers. From the perishable nature of these appendages
we have, unfortunately, no evidence as to the existence of
spines among fossil mammals; but from the foregoing
considerations, we are strongly inclined to think they may
be mainly characteristic of later epochs.

In this connection it is interesting to notice that the
spiny globe-fishes (Diodon, &c.), often termed ‘ sea-
hedgehogs,” in which the spines are bony and therefore
capable of preservation, do not date back below the
Tertiary, and that spiny fishes are unknown in earlier
epochs. Moreover, some—although by no means all—of
the paleozoic sea-urchins appear to have had very minute
spines. Hence it would rather seem as though the
history of spines has been exactly the opposite of that of
bony armour, which has tended gradually to disappear with
the advance of time.

Finally, we have to notice the general similarity in
appearance of so many of the more specialized spiny
mammals, due not only to their bristly coat, but likewise
to the general shortness or absence of the tail, and the
rounded, plump form of the whole body. The bearing of
this independent development of spines in so many groups
of mammals, together with the acquirement of a general
external resemblance in the creatures thus clothed, on
questions of wider import, forms the subject of the next
chapter, in which we shall also have to take into considera-
tion the conclusions reached in the previous one.

46 PARALLELISM IN DEVELOPMENT.

CHAPTER V.
PARALLELISM IN DEVELOPMENT.

In the course of the three preceding chapters, it has been
to a great extent our aim to show. that certain animals
may resemble one another very closely in general external
appearance, or may possess certain peculiar structural
features in common, without being in any way intimately
related; thus rendering it evident that such similarities of
form or structure have been independently acquired, and
are not inherited from a common ancestor. It has been
shown, for instance, that mammals belonging to several
distinct orders, or to different families of the same order,
may assume such a marked external resemblance to the
common mole as to be designated in popular language by
the same general title; while in other cases a more or less
striking approximation to the type of the ordinary hedge-
hog has resulted from the independent development of
very similar spines in totally distinct groups. Furthermore,
it has been pomted out in the first of the three chapters
that large tusks of very similar form may be independently
developed in the jaws of totally different distinct groups
of mammals; and even that certain extinct reptiles have
acquired tusks which are almost indistineuishable from
those of some of the carnivorous mammals, there being no
direct relationship between the members of these groups.
With regard to the external similarities of form in the
above-mentioned instances, we have seen reason to believe
that their inducing cause has been either similarity of
habit or the need of protection; while in the case of the
tusks the similarity may in certain instances be due to
the necessity for efficient offensive weapons. Be their
causes, however, what they may, it is evident that such
resemblances among animals, which are, so to speak,
accidental, indicate what may be termed a kind of parallel

NATURE OF PARALLELISM. 47

development ; and as such parallelism in development, or
shortly ‘‘ parallelism,” has recently attracted a good deal
of attention among biologists, we propose in this chapter
to present to our readers some of the more striking
instances of this feature. In the instances above alluded
to, the parallelism is either to a great extent shown in
external characters, or in structures which are easily
modified ; but, as we shall indicate in the sequel, in other
cases it affects deeply-seated structures ; and its inducing
cause is then very difficult to surmise on any of tbe
ordinarily accepted doctrines of evolution. It will, more-
over, be obvious that the acceptation of parallelism in
development—and accepted to a certain extent it must
undoubtedly be—throws a new difficulty in the inter-
pretation of the affinities of animals, since before saying
that an identity in some structural feature between the
members of any two groups indicates their relationship,
we have first of all to determine whether such similarity
of structure is due to parallelism, or is inherited from a
common ancestral type. As is so generally the case when
any new theory is started, a host of enthusiastic writers
have welcomed parallelism with acclamation, and have
attempted to apply it im a number of instances where
there is not at present sufficient evidence of its existence.
We have been told, for instance, that the American
monkeys have no relationship with their reputed cousins
of the Old World; that whalebone whales are not allied
to the sperm-whale and dolphins; that cats have no
kinship with civets or other modern carnivores; and that
the egg-laying mammals have been evolved from a reptilian
or amphibian stock, quite independently of all other
members of the mammalian class—their resemblances
being solely due to parallelism. At present, we confess,
we are totally unable to accept any of these conclusions,
and we think it somewhat improbable that if the members
of either of the above-mentioned pairs of groups had an
independent origin, they would have presented such a
similarity, both externally and internally, as we find to be
the case. Still, however, it must be borne in mind that
there is a considerable amount of evidence that the modern

48 PARALLELISM IN DEVELOPMENT.

horses of the Old World and their extinct cousins of the
New have been independently derived from earlier horse-
like animals; and if this be confirmed, it will be one of
the most remarkable known instances of parallelism, and
will tend to show that many others may exist. Turning
from these more or less problematical cases, we proceed to
notice seriatim certain well-marked instances of parallel
development as to the existence of which there can be no
doubt; commencing with those displayed in external
features, and then referring to such as are more deeply
seated.

As regards external resemblances, it is, of course—and
more especially so far as the lower animals are concerned
—not always easy to distinguish between parallelism and
mimicry. The above-mentioned instances of mole-like and
hedgehog-like animals belong, however, clearly to the
former category. The external resemblances existing
between swifts and swallows, which have no sort of
relationship to one another, likewise comes under the same
head. Another striking instance is to be found in the
assumption of a snake-like form, accompanied by abortion
of the limbs, by certain lizards, such as the familiar
English “blind worm,” it being very doubtful, to our
thinking, if this can be explained by mimicry. Still more
remarkable is the external resemblance presented by
whales and dolphins to fishes, and by the extinct fish-
lizards (Ichthyosaurs) to both; such resemblances being
clearly due to parallel development induced by the needs
of adaptation to a purely aquatic life. If, moreover, it
should prove that the whalebone whales have no connection
with the dolphins, we should then havea far more remark-
able instance of this feature, and one extending to internal
structures as well as to external form. A similar remark
will also apply to the case of the true seals and the eared
seals, which it has been suggested may be of independent
origin. The independent acquisition of wings by birds,
bats, and the extinct flying dragons, or pterodactyles, may
likewise certainly come under the heading of parallel
development, so far as external form and the adaptation
to a particular mode of life are concerned ; although here,

IN TEETH. 49

as in the instance of whales and fishes, the structural
features, by the aid of which the adaptation has been
brought about, are very different in the respective groups.
In respect to the teeth and dentition, many very well-
marked instances of parallelism may be adduced. We
have already referred to the similarity of the tusks in dif-
ferent groups of mammals; while in a previous chapter
we noticed the loss of upper front teeth, not only in the
modern ruminants, but likewise in the peculiar even-toed
ungulate known as Protoceras, of which the skull is figured
on page 53. The rhinoceroses likewise show a gradual
tendency to the loss of front teeth, resulting in the African
forms in the disappearance of the whole series from both
jaws. More remarkable, however, is the tendency to a
complete loss of the whole of the teeth in certain groups
of all the higher classes of vertebrates, as exemplified by
all modern birds, by turtles and tortoises, as well as certain
of the extinct flying dragons and fish-lizards among
reptiles, and by the great anteater, the scaly anteater,
and the echiduas, or spiny anteaters, among mammals ;
in all of which teeth are completely lacking. Moreover,
in many of these animals, such as birds, tortoises, and
probably the toothless flying dragons, the beak-like jaws
thus produced were sheathed in horn, thus showing a
kind of double parallelism, viz., the loss of teeth coupled
with the acquisition of a horny sheath to the jaws.
Another instance of parallel development afforded by
teeth relates to the gradual heightening of the crown and
the production of a flat plane of wear not only among
several distinct groups of hoofed mammals, such as the
elephants, horses, and ruminants, but likewise among the
rodents. It is evident that these high-crowned teeth
have been independently evolved in the three great groups
of hoofed mammals, of which the above-named creatures
are typical representatives ; and it may be added that the
molars of horses and ruminants present a further evidence
of parallelism in their assumption of a more or less
decidedly crescent-like (selenodont) structure, the essential
peculiarities of which are described in the eighth chapter.
This resemblance between the molars of horses and
E

50 PARALLELISM IN DEVELOPMENT.

ruminants is, however, comparatively remote, but in the
latter croup and the camels these teeth are so alike as to
require an expert to distinguish between them. Never-
theless, there is good evidence to show that the camels and
the ruminants, if not also the chevrotains, have acquired
their crescent-like molar teeth quite independently of one
another, and it therefore yet remains for those writers
who explain evolution by some mode of what they are
pleased to call natural selection to account adequately for
the similarity thus existing between structures of such
totally different origin, when they could have been made
equally efficient if unlike.

Passing from the consideration of teeth to that of limbs,
we may mention the remarkable similarity displayed in the
mode by which the lower segments of the limbs of the
even-toed and odd-toed hoofed mammals have been gradu-
ally elongated by the formation of a cannon-bone and the
disappearance of either three or four of the lateral digits ;
the cannon-bone in the horse consisting of but a single
element carrying one digit, while in the ruminants it
comprises two united elements supporting a pair of toes.
This is clearly a case of parallelism in development
attained by a shghtly different modification of principle.
The parallelism does not, however, stop here, since an
essentially similar type of cannon-bone has been produced
in birds; only that im that group (with the exception of the
ostrich) three long bones enter into its composition, which
is further complicated by the addition of a bone from
the ankle above. Sveing that in all these groups the
parallelism has been arrived at by a different structural
modification, the explanation of its mode of evolution is
much less difficult than in the case of the molars of the
camels and ruminants, where, as we have seen, the struc-
ture is practically identical.

Recent discoveries in North America have brought to
light the existence of a kind of secondary parallelism
among certain peculiar mammals which may be included
among the hoofed or ungulate division of that class. In
the even-toed group of that division, as exemplified by
the pigs and ruminants, it is the third and fourth digits

IN LIMBS. 51

which are symmetrical to one another, and tend to
develop at the expense of the others ; while in the odd-
toed group it is the third or middle digit which is
symmetrical in itself and undergoes an ultra development.
Now there are certain extinct creatures, which, while
having claws instead of hoofs at the ends of their toes,
yet are so closely related to the hoofed mammals that

Fie. 18.—Front and side views of the Hind Foot of Artionyz.
(After Osborn.)

their separation therefrom is almost impossible. In one
of these, which has long been known in Europe as the
chalicothere, the third digit, as in the odd-toed hoofed
mammals, is symmetrical in itself, and larger than
either of the others; whereas in the newly-described
animal known as Artionyx the third and fourth digits
resemble those of the even-toed division of the hoofed
mammals in being larger than the others and symmetrical
to a line drawn between them. While, therefore, we have
clearly a parallel development on different lines between
the odd and even-toed hoofed animals im the development
of a cannon-bone, these extinct clawed, hoof-like mammals
(for want of a better expression) show a parallel parallel-
ism (to coin another expression) which, if it had continued,
might have resulted in the development of a two-clawed
£2

52 PARALLELISM IN DEVELOPMENT.

ruminant and a two-clawed horse. To our thinking, this
is indeed one of the most curious phases of development
yet discovered.

In addition to the parallelism in the evolution of their
molar teeth and limbs, the hoofed mammals likewise
exhibit the same feature in regard to the second vertebra
of the neck. As many of our readers are probably aware,
the first, or atlas vertebra of the neck, turns with the
head when the latter is moved sideways, the axis of
rotation being formed by a process—the odontoid process
—arising from the second or axis vertebra, and projecting
into the central hollow of the atlas. Now in pigs and
likewise all the primitive hoofed mammals, the so-called
odontoid process is (as in ourselves) in the form of a
flattened peg. On the other hand, in the ruminants, the
modern horses, and the camels, which, as we have seen,
represent three distinct phyla of the order, this peg has
become modified into a spout-like half-cylinder, which
must clearly have been separately evolved in each of these
three groups. It is true that such a half-cylinder affords
a far better basis of support for a heavy skull than does a
mere peg; but the curious part of the matter is why these
half-cylinders should be so exactly alike in the different
groups, seeing that, as it would not be difficult to design
some other structural modification by which the same end
might have been attained, there is no necessity for their
similarity.

Our last example of parallelism will be drawn from two
groups of extinct North American hoofed mammals, to
which brief allusion has already been made in the chapter
on “Tusks and their Uses” ; the one group being known as
uintatheres, while the second is represented by a single
species to which the name of Protoceras has been applied.
Now, although the uintatheres have five-toed feet approxi-
mating in structure to those of elephants, while in Proto-
ceras each foot approximated to the ruminant type, in both
groups the skull, as shown in the accompanying figure,
was armed with several pairs of large, irregular, bony
processes, which during life may have been sheathed in
horn ; while in each case a pair of long tusks projected

IN THE TAIL. 53

from the upper jaws, which were totally devoid of front
or incisor teeth. Had such skulls been discovered without
any indication as to the nature of the limbs with which
they were associated, they would inevitably have been
assigned to the same group of animals. The resemblance
existing between thei, is, however, clearly due to parallel
development, and we are thus shown another striking
instance of caution necessary in endeavouring to determine
the affinities of extinct animals from the evidence of in-
complete remains.

Fie. 19.—Skull of Protoceras. (After Osborn.)

Our last instance of parallelism is alluded to in a later
chapter, entitled ‘‘'The Oldest Fishes and their Fins,” in
the course of which it is shown that while both the most
ancient birds and the oldest fishes had long tapering tails
with the joimts of tue backbone gradually diminishing in
size, and each carrying either a pair of feathers or a pair
of fin-rays, in all the modern representatives of the former
group, and in a large section of the latter, the end of the
vertebral column has been aborted into a composite bone,
from which either the feathers or the rays of the tail
diverge in a fan-like manner.

In conclusion, we may say that although there is no
very great difficulty in satisfactorily accounting for external
parallelism obviously due to the necessity for adaptation
to a particular mode of life, or in explaining those instances
where a particular result has been brought about by

54 PARALLELISM IN DEVELOPMENT.

different methods, yet when we find precisely similar
structural modifications in different groups of animals
which clearly cannot be traced to a common ancestry, and
for which equally efficient substitutes could be readily
suggested, we are fain to confess that the ordinarily
accepted explanations of evolution appear to us altogether
inadequate. Putting this aspect of the matter aside, our
readers will, however, see from the imperfect sketch given
above, what an important factor in evolution parallel
development really is, and how largely it is likely in the
future to modify our present views as to the mutual
relationships of animated nature.

TOOTHED WHALES AND THEIR ANCESTRY. 55

CHAPTER VI.
TOOTHED WHALES AND THEIR ANCESTRY.

Wiruiw the entire limits of the great mammalian class,
there are, perhaps, no creatures which arouse a larger
amount of interest—both among the general public and
among naturalists—than those included under the names
of whales, dolphins and porpoises, and collectively known
as cetaceans. One reason for this universal interest is,
doubtless, that among these denizens of the deep are com-
prised the largest animals, not only of the present day,
but likewise, so far as our information allows us to speak,
of all epochs. Then, avain, the fact that such apparently
fish-like creatures are really warm-blooded mammals,
suckling their young in the manner distinctive of all other
members of the class, and being under the necessity of
coming to the surface at certain intervals for the purpose
of breathing, cannot fail to strike even the most unobser-
vant mind as being something quite beyond the ordinary.
Moreover, the momentary glimpses which in general are
all we obtain of these animals, and the halo of mystery
which still to a great extent enshrouds their mode of life,
are likewise important elements in generating the wide-
spread interest they arouse. To the zoologist, cetaceans
are indeed not only of prime importance as being the sole
mammals which have assumed a purely fish-like form, and
have become so thoroughly adapted to a completely pelagic
life as to be unable to exist on land, but their study gives
rise to many problems as to their origin and relationships,
and the mode in which they attained their present con-
dition.

Into the consideration of the leading external features
of cetaceans we need not enter very fully, merely pointing
out that while the general contour of the body is fish-
like, the tail-fin, or flukes, differs essentially from that
of a fish in being horizontal instead of vertical; while

56 TOOTHED WHALES AND THEIR ANCESTRY.

in place of the two sets of paired fins characterizing a
fish, a whale has but a single pair of flippers representing
the greatly modified fore limbs of other mammals.
The hind limbs have, indeed, been completely lost
externally, although more or less imperfect traces of
them may still be detected deeply imbedded among the
muscles of the body. In the great majority of the group
the back is furnished with an upright fin, very similar in
appearance to the unpaired back-fin of a fish. Whereas,
however, such a back-fin is constantly present in fishes,
in cetaceans it may be absent or present in different species
of the same genus; while if we were to cut through such a
fin we should find a total absence of the slender spine-like
bones characterizing those appendages in a fish ; a similar
condition also obtaining in the flukes. In marked contrast
to the scaly armour of the majority of modern fishes, the
skin of a cetacean is for the most part completely naked ;
although the frequent presence, in the young state at
least, of a few scattered bristles in the region of the mouth
is of itself sufficient to indicate the derivation of these
strangely modified creatures from more ordinary mammals.
As regards their coloration, we may again, however, note
a similarity to most pelagic fishes, in that while the upper
parts are generally dark, the lower surface of the body is
of a light hue; this arrangement being, of course, designed
to render all these animals as inconspicuous as possible
when viewed in the water either from above or from below.
Although the flippers show no external indications of
toes, and are unprovided with nails, yet their internal
skeleton comprises the same elements as occur in the
limbs of any ordinary mammal, and is thus quite different
from that of a fish. This structural similarity is, however,
to a certain degree obscured by the alteration in the form of
the bones, and also by the circumstance that the number
of joints in the skeleton of the individual toes is increased
beyond the normal. As external ears would be mere
useless incumbrances, these appendages are absent ; while
the aperture of the ear itself is reduced to an extremely
minute size. To prevent the ingress of water during the
periods of submergence, the apertures of the nostrils, which

CLASSIFICATION. 57

may be either double or single, can be completely closed
at will, and are only opened at such times as the creatures
come to the surface to breathe, when a column of water is
generally thrown up by the rush of expired air let loose

Fig. 20.—The Bridled Dolphin. (From True, Bull. U.S. Nat. Museum.)

shortly before the head reaches the surface. In all their
internal structures, as well as in the mode of production
and nourishing of their young, cetaceans conform strictly
to the ordinary mammalian type; and we accordingly see
that their assumption of a fish-like form is, with the
exception of the loss of the hind limbs and the modifi-
cation of the front pair into flippers, mainly superficial.
In departing from the fish-type in having the expansion
of the tail-fin horizontal instead of vertical, the necessity
of having an organ capable of bringing them rapidly
to the surface has been the inducing cause; while in
order to prevent their blood from being reduced below
the proper temperature by the chill of ‘the surrounding
water, the whole body is invested with a thick layer
of oily fat, commonly known as the blubber, beneath the
skin.

Existing cetaceans are divisible into two great groups,
distinguished as the whalebone whales and the toothed
whales ; the latter group including sperm-whales, together

58 TOOTHED WHALES AND THEIR ANCESTRY.

with the grampuses, porpoises, and dolphins. The most
obvious distinction between these two groups, as the terms
applied to them indicate, relates to the presence or absence
in the adult condition of true teeth.

Confining our attention in the present chapter to the
toothed cetaceans, of which the dolphins and their allies
are the least specialized representatives, we find that the
two jaws may be in some cases provided with a full series
of teeth, while in other forms the number of teeth may be
reduced to a single pair, or even, as in the male narwhal
(Fig. 9), to a solitary tusk. Whether, however, the teeth
be many or few (and in the female narwhal there are
none of any functional importance), the structure known
as whalebone is never developed in the mouth; while all
the members of the group are further distinguished from
the whalebone whales by the circumstance that the
nostrils invariably open by a single external aperture,
which is very frequently in the form of a transverse
crescentic slit, closed by an overhanging valve. In the
latter respect these cetaceans are more specialized than
are the whalebone whales; and as the presence of teeth
in the former indicates that they could not have been

Fria. 21.—The last six Upper Teeth of the Killer. (After Sir
W. H. Flower.)

derived from the latter, it is evident that the two groups
are of extreme antiquity, and have undergone a parallel
development. Till recently, it has indeed been considered
that they were divergent branches from some common
ancestral type; but, as mentioned in the chapter on
‘‘ Parallelism in Development,” it has been lately suggested

NATURE OF TEETH. 59

that each may have had a totally distinct origin, although
the evidence in favour of such a view is, at present at
least, far from conclusive.

In the structure of their teeth, the modern toothed
whales differ very widely from the generality of mammals.
In the first place, their teeth are always of the simple
structure shown in Fig. 21, having conical or compressed
crowns, and undivided roots; while, secondly, there is
only one single series developed, the replacement of the
anterior ones characterizing the majority of mammals
being wanting. From this simple structure of their teeth
it has been argued that these cetaceans are among the most
primitive of all mammals; but, altogether apart from the
conclusive evidence that all whales (as proved by their
breathing air) are derived from land mammals, it has
recently been shown by the researches of Dr. Kiikenthal, of
Jena, that this view is quite untenable. By examining em-
bryos of young cetaceans of this group, that observer has
demonstrated that there are actually rudiments of a second
series of teeth, which, although never coming to maturity,
serve to show that there were once two complete sets, and
that the permanent teeth correspond, in part at least, to
the milk-teeth of other mammals; thus indicating that the
present state of the cetacean dentition is a degraded one.
Hitherto it has not, indeed, been shown by embryology
that the teeth of this group were originally of a complex
type (although in the case of the whalebone whales this
has been demonstrated), but, fortunately, here paleontology
comes to our aid. Thus in the middle of the Tertiary
period there occur remains of what may be termed shark-
toothed dolphins (squalodonts), in which the permanent
teeth are differentiated into distinct series, corresponding
to the incisors, canines, premolars, and molars of other
mammals; while, for all we know to the contrary, there
may also have been a regular replacement of the more
anteriorly placed teeth. In these shark-toothed dolphins
the molar teeth, instead of being of the simple structure
of those represented in our illustration, were severally
implanted in the jaws by two perfectly distinct roots ;
while their large, laterally compressed, and somewhat fan-

60 TOOTHED WHALES AND THEIR ANCESTRY.

shaped crowns were furnished with a number of cusps on
their hinder cutting-edges. Indeed, these teeth much
resemble the premolar teeth of a dog or the molars of a
seal; and they obviously serve to indicate a transition from
the modern toothed cetaceans towards ordinary mammals.
This, however, is by no means all, since in a still earlier
portion of the same division of the Tertiary period there
occur other cetacean-like animals known as zeuglodonts,
which have still more complicated teeth, and otherwise
depart further from the modern cetacean type—so much so,
indeed, that they have been regarded by some writers as
more nearly allied to the seals. In our own opinion they are,
however, undoubtedly primitive cetaceans, and thus serve,
not only to connect the present group with other mammals,
but also, in conjunction with the shark-toothed dolphins, to
show that the simple teeth of the former are clearly pro-
duced by degeneration from a complex type. As regards
the particular group of land mammals from which whales
were derived, it has been thought that their nearest allies
are with the ancestors of the pig-like hoofed mammals.
This, indeed, is the view of Sir W. H. Flower; but we
confess that from the nature of the teeth of the two extinct
groups above mentioned, coupled with certain resemblances
of the skeleton of the zeuglodonts to those of seals, we
are rather more inclined to look among flesh-eating land
mammals for the lost ancestors. Still, however, it must
be remembered that in the early Eocene period, which is
probably the very latest epoch at which cetaceans could
have originated, the distinction between carnivorous and
hoofed mammals was but imperfect, so that, after all, the
ancestral cetacean stock may well have been of an
extremely generalized type. At present, however, we are
almost completely in the dark in all that concerns this
interesting subject.

By far the largest of all the toothed whales is the
gigantic sperm-whale, the typical representative of a family
characterized by the absence of teeth in the upper jaw of
the adult, while those of the lower jaw are very variable
both as regards form and number. In the sperm-whale, of
which the male attains a length of between fifty and sixty

SPERM-WHALES, ETC. ~ 61

feet, the lower teeth vary in number from fifty to sixty on
each side, and are characterized by their large size and
pointed crowns, upon which there is not a trace of enamel.
Another characteristic feature of this animal is the
enormous size of the head, which terminates in an abruptly
truncated muzzle of great depth, and in a cavity of which
is contained a peculiar oily substance, yielding when
refined the well-known spermaceti. An even more valuable
product of this animal is ambergris, which, while accumu-
lated as a concretion in the intestine, is generally found
floating on the surface of the sea ; in appearance it is an
amber-coloured substance, containing a number of the
horny beaks of the squids on which the sperm-whale
subsists.

Omitting mention of the lesser sperm-whale—the only
other member of the first division of the family—we pass
on to mention the bottle-nosed and beaked whales,
characterized by having all the lower teeth, with the
exception of a single pair, rudimentary, and concealed in
the gum. In the bottle-noses—so named from the extreme
convexity of the crown of the head of the adult males,
which rises suddenly above the short beak—there is but a
single pair of teeth, situated in the front of the lower jaw,
and even these are invisible during life. These whales,
of which there is but a single well-defined species.
(Hyperoédon rostratus), although not exceeding some thirty
feet in length, are valuable on account of their oil,
as well as from yielding spermaceti from their skulls. In
contradistinction to the sperm-whale, they carry, in
common with the beaked whales, a large back-fin.
In the beaked whales, of which there are three existing
genera, the skull is produced into a long beak, of which
the upper half is formed by a solid bone of ivory-like
density ; while in the lower jaw there are either one or two
pairs of teeth, which, although variable in position, are
generally of large size, Itis one of these whales (Mesoplodon
layardi) which is alluded to in the chapter on ‘‘ Tusks and
their Uses,” as being provided with teeth of such a size
as actually to impede the free opening of the mouth.
From their general avoidance of the neighbourhood of

62 TOOTHED WHALES AND THEIR ANCESTRY.

coasts, and their apparently somewhat solitary habits,
extremely little is known of the life-history of the beaked
whales, of which the skeletons are but poorly represented
in our museums. At the present day very rarely seen in
the English seas, during the Pliocene period these whales
must have been extremely numerous in the North Sea,
since their fossilized beaks are amongst the most common
vertebrate fossils obtained from the crags of Suffolk and
Essex. The same deposits, together with others of corre-
sponding age on the Belgian coasts, havealso yieldedremains
of a number of extinct whales, more or less closely allied
to the sperm-whale, thus indicating that the latter is the
last survivor of a once numerous group. The teeth of
many of these fossil sperm-whales differed, however, from
those of their living cousins in having their crown capped
with enamel.

Fre, 22.—The Indian Porpoise. (From True, Bull. U.S. Nat. Museum.)

In the general presence of numerous teeth in both the
upper and the lower jaws, the dolphins and their allies
the porpoises, killers, and white-whale differ from all the
above-mentioned forms, and thus constitute a second family
—the Pelphinide. The group is a numerous one, which is
split up into a number of genera, some of which are by no
means easy to distinguish. They may, however, be roughly
ranged under two main divisions, in one of which the
muzzle is short and rounded, as in the porpoises and black-
fish, while in the other, as represented by the dolphins
(Fig. 20), it is produced into a longer or shorter beak, of
which the base is marked off from the main portion of the
head by a distinct re-entering angle. The most aberrant
member of the first group is the spotted Arctic narwhal, of
which a brief notice, accompanied by a figure, was given

PORPOISES AND KILLERS. 63

in the chapter on “‘ Tusks.” Allied to the narwhal is the
beautiful white-whale (Beluwya), which is likewise a
northern species, distinguished by its glistening white
skin, the absence of any tusk, and the presence of
numerous well-developed teeth in the fore part of the
jaws ; neither of these species having a back-fin.
Although the name “porpoise” is applied indiscriminately
to several members of the family, it should properly be
restricted to a few comparatively small-sized species
characterized by the presence of some twenty-five small
and flattened teeth with spade-shaped crowns on either
side of each jaw. Porpoises are among the most common
and familiar of all cetaceans, their rolling gambols being
well known to all who have made a voyage; but
whereas the common porpoise has a distinct back-
fin, in the species represented in our illustration that
appendage is lacking. Less familiar, on the other
hand, are the much larger and handsomely coloured
killers, or grampuses (Urea), differing by the great size
of their teeth (Fig. 21), which are usually twelve in number
on each side, and the great development of the back-fin.

Fie. 23.—Pacific Black-Fish. (From True, Bull. U.S. Nat. Jus.)

Attaining a length of about twenty-five feet, the killer
derives its title from its rapacious habits; a single specimen
having been known to swallow several whole seals in
succession, while not unfrequently several individuals have
been observed to combine their forces to attack and kill the
larger members of the order. Killers may always be
easily recognized while swimming near the surface by the

64 TOOTHED WHALES AND THEIR ANCESTRY.

great height of their nearly vertical back-fins. Allied
cetaceans with smaller teeth (Orcella) frequent the Bay of
Bengal and ascend some distance up the Irrawadi. Another
well-marked type is the black-fish (Fig. 23), characterized
by its remarkably short and rounded head, the uniformly
black hue of the skin, and by the eight or twelve small
and conical teeth being confined to the front portion of the
jaws.

There are other less well-known representatives of this
eroup which we have not space to notice; and we
accordingly pass on to say a few words about dolphins—a
term which should be restricted to those forms having a
distinctly marked beak. Since, however, sailors will
persist in speaking of dolphins indifferently, either as
bottle-noses or porpoises, the inexperienced landsman
must be on his guard not to confound them when
thus spoken of either with the bottle-nosed whales
or the true porpoises. Dolphins, which are divided into
numerous genera, according to the number of their teeth,
the length of the beak, and other characters, are all
comparatively small species, seldom exceeding some ten
feet in length ; and while the great majority are marine, a
few ascend some of the larger tropical rivers, such as the
Amazon. Fish of various kinds constitute their usual
prey ; but one peculiar species recently described from the
Cameruns district is believed to subsist on sea-weed. Of
the better-known types, the common dolphin represents
the genus Delphinus, the bottle-nosed dolphins constitute
a distinct genus (Tursiops), while the long-beaked dolphins
are separated as Steno.

To the foregoing group of beaked dolphins the ordi-
nary observer would, doubtless, be disposed to refer three
peculiar species severally restricted to the larger rivers of
India, the Amazon, and the mouth of the La Plata river,
but as these differ more or less markedly from other
dolphins in certain structural features they are referred to
a distinct family. Moreover, since these peculiarities
approximate to a more generalized type, while their fresh-
water habits and scattered distribution indicate extreme
antiquity, it is not improbable that these three dolphins.

FRESH-WATER DOLPHINS. 05

are the most primitive of all existing cetaceans. At
present we have, indeed, no evidence of fossil forms allied
to the susu or Gangetic dolphin (Platanista); but in the
older Tertiary deposits, both of the United States and
Europe, there occur the remains of dolphins evidently
nearly allied to the two existing South American species
(Inia and Stenodelphis), and thus clearly proving the
antiquity of those types. It may be added that it is
probable that the ancestors of the cetaceans which first
took to an aquatic life were inhabitants of fresh-water,
and it is therefore only what we should expect that the
most primitive of the existing representatives of the order
were likewise of fluviatile habits. On the other hand, it
must be confessed that the similarity in structure of the
widely separated existing fresh-water dolphins is some-
what difficult to account for on this hypothesis.

Te

66 WHALEBONE AND WHALEBONE WHALEg.

CHAPTER VII.
WHALEBONE AND WHALEBONE WHALES.

Sreine that the substance so-called has nothing in common
with true bone, many zoological writers object to the use of
the term ‘‘ whalebone”; and they have accordingly proposed
the substitution of the word ‘‘ baleen,’’ which has been
specially coined for the purpose. To our thinking, there is,
however, no necessity for this substitution of a word of
foreign origin for such a well-known English name, any
more than there is for replacing the native term ‘ black
Jead”’ by its foreign equivalent ‘‘ graphite.” Everybody
knows what is meant by whalebone or black lead, while
comparatively few are familiar with the terms “ baleen”
and ‘graphite’; and as the two former are every bit as
good as their foreign substitutes, we prefer to employ them.
If, indeed, there should exist any persons so misguided as
to imagine either that whalebone is equivalent to the bone
of whales, or that black lead has any sort of affinity with
load, we fear that the substitution of the terms ‘‘baleen”’
and “graphite” would not much aid in removing their
ignorance.

The substance which we accordingly take leave to call
whalebone is one of the chief essential characteristics
by which the whalebone whales are distinguished from
the toothed whales forming the subject of the preceding
chapter. As our readers are probably aware, this
substance is attached to the upper surface of the mouth
of the whale, from which it depends in the form of
a series of parallel, narrow, elongated, triangular plates,
placed transversely to the long axis of the mouth,
with their external edges firm and straight, but the
inner ones frayed out into a kind of fringe. The
longest plates of whalebone are situated near the middle
of the jaw, from which point the length of the plates
gradually diminishes towards the two extremities, where

ARRANGEMENT OF WHALEBONE. 67

they become very short. There is, however, whalebone and
whalebone, and whereas in the Greenland whale the length
of the longest plates varies from some ten to twelve feet,
while the total number of plates in the series is about 380,
in the great rorquals or fin-whales the length is only afew
inches, while the number of plates is considerably less.
To accommodate the enormous whalebone plates of the
Greenland whale, the bones of the upper jaw are greatly
arched upwards, while the slender lower jaw is bowed out-
wards, thus leaving a large space both in the vertical and
horizontal directions, the transverse diameter of the space
being much wider below than above. When the mouth is

Fia. 24.—Section through the Skull of the Greenland Whale, with
the outline of the soft parts. he arrows indicate the position of
the nasal passage and aperture.

closed, the plates of whalebone are folded obliquely back-
wards, with the front ones lying beneath those behind
them ; but directly the jaws are opened, the elastic nature
of this wonderful substance causes it to spring at once into
a vertical position, and thus form a sieve-like wall on both
sides of the mouth, the thin ends of the plates being pre-
vented from pushing outwards by the stiff lower lip which

F2

68 WHALEBONE AND WHALEBONE WHALES.

overlaps them. By elevating its enormous fleshy tongue
within the cavity thus formed, the whale causes the
enclosed water to rush out between the plates, leaving such
small creatures as it contained lying high and dry on the
surface of the tongue ready for swallowing.

In structure, whalebone (which, by the way, although
black in the Greenland whale, is white in some of the
other species) is of a horny nature, and grows from
transverse ridges on the mucous membrane of the roof of
the mouth ; being, in fact, nothing more than an ultra-
development of the ridges on the palate of a cow, hardened
and lengthened by an excessive growth of a horny super-
ficial or epithelial layer. The whole of this stupendous
horny growth takes place, however, after birth, young
whales having smooth palates, with no trace of the horny
plates. Although at birth young whalebone whales show
no traces of the substance from which the group derives
its name, they equally exhibit no evidence of the
presence of teeth. If, however, their jaws be examined at
a still earlier stage of development, it will be found that
there are a number of small teeth lying within a groove
beneath the gum on each side of both the upper and the
lower jaws. Previous to birth these teeth become absorbed,
and thus never cut the gum. Their presence in this
transitory stage is, however, of the deepest interest to
the evolutionist, since they unmistakably indicate the
derivation of the whalebone whales from ancestors
provided with a full series of functional teeth. This,
however, is not the whole of the story these rudi-
mentary structures have to tell. From the recent
investigations of Dr. Kikenthal, it appears that in addition
to the above-mentioned tooth-germs, the jaws of very
young whales likewise exhibit traces of a still earlier
deciduous series of milk-teeth; thus showing that the
former correspond to the permanent series of other
mammals. Accordingly, these tooth-germs do not represent
the functional teeth of the toothed whales, which, as we
have seen in the chapter on that group, correspond to the
milk-teeth of ordinary mammals. Even more remarkable
are certain observations relating to the structure of these

CHARACTERISTICS. 69

tooth-germs. It has been shown, indeed, that the teeth in
the latter part of the series, when first formed, consist of a
number of adjacent cusps, and that as development
proceeds these cusps become completely separated from
each other so as to constitute distinct individual teeth of
a simple conical form.

This discovery is of the very highest import, since it
serves to indicate how the numerous simple conical teeth
of the dolphins and other toothed whales have probably
been derived by the splitting and subdivision of originally
complex cusped teeth more or less closely resembling
those of the extinct zeuglodonts referred to in the last
chapter.

Being primarily distinguished from the toothed whales
vy the total absence of teeth after birth and the presence
of whalebone in the adult condition, the whalebone whales
present certain other distinctive characters to which we
may now briefly allude.

In the first place, the whales of this group differ
externally from all those furnished with teeth in that their
nostrils open externally by two distinct longitudinal slit-
like apertures ; while, if we cut into the head, we shall find
that there is a distinct organ of smell, of which all traces
have disappeared amcng the toothed whales. Moreover,
instead of the skull being invariably unsymmetrical in the
region of the nose, as it is in the latter group, it retains
the normal symmetry ; while, instead of the mere nodules
which in the toothed whales represent the nasals of other
mammals, in the whalebone whales these bones are fairly
well developed. Then again, the lower jaw of any member
of the present group may always be distinguished from
that of a toothed whale not only by the absence of teeth,
but likewise by the circumstance that each of its branches
is much bowed outwards in the middle, while their anterior
extremities are connected together merely by ligamentous
tissue, instead of by a bony symphysis of greater or lesser
length. Many other points of difference between the two
groups might be cited, but we have especially referred to
those mentioned above, for the reason that while the
presence of whalebone indicates that in one respect the

70 WHALEBONE AND WHALEBONE WHALES.

members of this group are more specialized than their
toothed cousins, in regard to the structure of the skull in
the region of the nose and the retention of an organ of
smell, as well as in the double apertures of the nostrils,
they depart less widely from the ordinary mammalian
type. And it is from this evidence that zoologists regard
the two main groups of whales as being widely divergent
branches from a common ancestral stock, if, indeed, they
do not go so far as to consider that each has had a totally
independent origin.

With regard to the number of forms by which they are
represented, the whalebone whales are far less numerous
than the toothed group, the whole of them being included
within a single family. What the group lacks in number
is, however, amply made up by the great bodily size of
its various representatives. Among the toothed whales,
the sperm-whale alone attains gigantic dimensions;
whereas in the present group there are several species,
such as the Greenland whale, which nearly equal that
enormous creature in bulk, while two of the rorquals far
surpass it. This, however, is by no means all, for whereas
the great majority of the dolphins and porpoises are
relatively small cetaceans of less than twenty feet in
length, the smallest member of the present group is the
southern pigmy whale, which attains a length of twenty
feet, while next to this comes the lesser rorqual, whose
length is frequently close on thirty feet.

Of the various genera of this group, the most specialized
are the typical or right whales (Lalena), in which the
black whalebone is far longer and more elastic than in any
of the others, except the pigmy whale; while, in order to
accommodate it in the mouth, the skull has the
palate narrower and much more highly arched, and
the two branches of the lower jaw more outwardly
bowed than in the other members of the group. Ex-
ternally, these whales—which are commercially of far
greater value than the undermentioned rorquals—are
characterized by the inordinately large dimensions of the
head, by the smooth throat, the moderate length of the
flippers, and the total want of a back-fin. So gigantic

RIGHT WHALES. 71

indeed, is the size of the mouth in these whales that its
capacity actually exceeds that of the whole of the other
cavities of the body; and yet the size of the throat is so
smallas almost to justify the common nautical saying that
a herring will choke a whale. There are but two well-
defined species of right whales, viz., the Greenland or
Arctic whale (B. mysticetus), and the southern right
whale (B. australis), the latter of which was nearly
exterminated some centuries ago in the Atlantic by the
Basque whalers, while the former is only too likely to share
the same fate at the hands of their modern successors in
the Arctic seas. Of the two, the Greenland whale is
decidedly the more specialized, having a much larger head
and longer whalebone, and is in this respect facile princeps
among its tribe ; although, as it only measures from forty-
five to fifty feet in length, it is inferior in point of size to
the rorquals. The skeletons of both these whales are cha-
racterized by the whole of the vertebre of the neck being
welded together into a solid mass; and the same feature
is exhibited by those of the pigmy whale (Neobalena) of the
southern seas, which, as already mentioned, is a mere
dwarf among giants, asitdoes not exceed some twenty feet
in total length. Agreeing also with the right whales in
its smooth throat, the pigmy whale differs by having a
small hook-like fin on the back, while its long and elastic
whalebone is white instead of black. Far larger than
the last, the great grey whale of the Pacific (Rhachiancctes)
forms a kind of connecting link between the right whales
and the rorquals, having the smooth throat and finless
back of the former, while its whalebone is even shorter
and coarser than in the latter; the palate consequently is
but little vaulted, and the entire head smaller in proportion
to the body.

The remaining whales of this groupare divided into hump-
backs (Megaptera) and rorquals or finners (Balenoptera) ;
both of which are characterized by the presence of a
number of parallel groovings or flutings in the skin of the
throat, as well as of a back-fin (whence their name of
finners or fin-whales), and also by the shortness and
coarseness of their whalebone, which is generally of a

va WHALEBUNE AND WHALEBONE WHALES.

yellowish colour. Their flukes are, moreover, less expanded
than are those of the right whales ; while, as already said,
their heads are relatively smaller and lower, with the
cavity of the mouth much less vaulted. In their skeletons,
the vertebre of the neck differ from those of the night
whales in being longer and completely disconnected from
one another; and in this respect the Pacific grey whale
holds a position intermediate between the two groups.
Hump-backs, of which there is but a single species, are
specially characterized by the shortness and depth of
the body, which behind the shoulder rises above the level
of the back-fin, and by the exceeding elongation and
slenderness of the flippers, which are about equal to
one-fourth the total length of the animal. The female
hump-back, which somewhat exceeds her partner in size,
attains a length of from forty-five to fifty feet, or about the
same as that of the Greenland whale. An enormous whale,
believed to belong to this species, became some years ago
entangled in the telegraph cable line off the coast of
Baluchistan with three turns of the cable round its body.
On the other hand, in the rorquals, the body is long and
slender, while the flippers are small and pointed. Of the
four well-established species of this genus, the blue or
Sibbald’s whale (Bb. sibbaldi)—the “ sulphur-bottom ” of
the American whalers—enjoys the proud distinction of
being the largest of all known animals, whether living or
extinct, attaining the enormous length of from eighty to
eighty-five feet; while the common rorqual (B. musculus)
comes in a good second with a length of from sixty-five
to seventy feet. Both the others are, however, con-
siderably smaller.

As regards their distribution in time, whalebone whales
have left their remains commonly enough in the Plio-
cene strata of all parts of the world, and they likewise
oceur in those of the Miocene period; but, although a
single vertebra from the Eocene beds of Hampshire has
been assigned to a member of this group, there is at
present no decisive evidence that they had come into
existence at such an early date. Since most of the Pliocene
species are of smaller dimensions than their living repre-

DESTRUCTION BY MAN. 73

sentatives, it appears that these marvellous creatures had
only attained their maximum size shortly before the time
when their very existence was to be threatened by the
relentless hand of man.

Formerly the only members of this group of whales
which were thought worthy of general pursuit were the
right whales; the shortness of their whalebone, coupled
with their relatively small yield of oil, and their tre-
mendous speed, rendering the rorquals scarcely worth the
trouble and risk of hunting. Of the two right whales, the
Greenland species, as being the more abundant, received
the greatest share of attention ; and so relentless has been
its pursuit, that it is now either well-nigh exterminated
from many of its ancient haunts, or has retreated still
farther north to regions almost impossible of access. As
showing how the constant persecution in the Greenland
seas has told upon the size of the comparatively few
remaining individuals of this species, it may be mentioned
that the eleven specimens killed there during the season
1890-91 yielded an average of less than 8 cwt. of whale-
bone, whereas in five taken during the same season in
Davis Strait the average yield was more than double this
amount. In consequence of this diminution in the number
and size of the Greenland whale, the value of whalebone
has of late years gone up enormously; and whereas
some time ago whalebone of over six feet in length sold at
£1000 per ton, in 1892 it had reached the enormous price
of upwards of £2800 per ton. The southern right whale
yields a smaller quantity of rather shorter and less valuable
bone, now selling at from £1600 to £1800 per ton; the
quantity obtained from a well-grown example varying from
800 to 1200 pounds. The amount of oil produced by a
whale of the same species averages from eight to fourteen
tons, of which the present market value is about £28 per
ton. If the unfortunate animals are not allowed some
vespite, it is only too probable that the supply will before
long cease altogether.

As another result of this growing scarcity of the Green-
land whale, attention has been directed to the previously
despised rorquals and hump-backs; the employment of

74 WHALEBONE AND WHALEBONI WHALES.

steam whaling vessels, and the use of explosive harpoons.
having enabled the whalers easily to cope with the greater
speed of these cetaceans. At Hammerfest, a special
‘‘ fishery” has, indeed, been established for the capture of
rorquals, where the take of these animals is now large.
The products of these whales are, however, nothing like
the value of those of the Greenland species; and if the
latter, together with the southern right whale, be so nearly
exterminated as to render pursuit no longer profitable,
the supply of long whalebone will absolutely come to an
end.

Postscript.—Since the foregoing was written, the author
lias discovered that certain fossil toothed whales from
Patagonia had their nasal bones nearly as well developed
as in the whalebone whales ; this discovery removing one
of the difficulties in regarding the latter as the descendants
of the former,

RUMINANTS AND THEIR DISTRIBUTION. ras

CHAPTER VIII.
RUMINANTS AND THEIR DISTRIBUTION.

From early times we find the function of ruminating, or
“chewing the cud,” recognized as a peculiarity of the
group of mammals known in semi-popular language as
ruminants. In ‘“ Deuteronomy,” for instance, the animals
permitted for food are those that “ chew the cud and part
the hoof” ; while the swine, “ which part the hoof but do
not chew the cud,’ are forbidden. On the other hand,
the camel, which chews the cud but has not paired hoofs,
is in the forbidden list. In the permitted animals we
thus have a recognition of the group of ruminants as
represented by oxen, sheep, and deer; of which no better
short definition can be given than that they chew the
cud and have each foot furnished with a pair of hoofs
symmetrical to a vertical line between them. The want of
the paired hoofs in the camels, which are also cud-chewers,
show, however, that these two characteristics will not hold
good for the entire group. As we proceed, we sball find
that there are structural features, common to the group,
in addition to the peculiarity of rumination; but before
going further, we may observe that the recognition of
their paired hoofs, coupled with the absence of rumination,
is an exact statement of the relationship of the swine to
the true ruminants.

The word “ruminant”? comes from the Latin rumen,
which was applied both to the “cud” and to that part of
the stomach in which the latter is contained previous to
chewing. The Greeks had a word meruko or merukizo
(from meruo, to revolve), to express this action of cud-
chewing, and a derivative from the former was used
by Aristotle to designate ruminants, who thus first
distinguished the group by a definite name. This early
recognition of the ruminants as a group is probably due
to their importance to man, the Biblical record showing

76 RUMINANTS AND THEIR DISTRIBUTION.

that they yielded the only mammalian food permitted to
the Hebrew, and this pre-eminence as a source of food has
scarcely decreased tothe present day. They are, moreover,

Vic, 25.—skeleton of the Extinct Irish Deer—a typical Ruminant.

now the dominant type of larger mammals, as witness the
herds of bison which lately roamed over the American

NATURE OF RUMINATION, Gils

prairies, and the droves of antelopes on the African
veldt.

Commencing with the function of rumination, we may
observe that it is a re-mastication of grass or other
vegetable food, swallowed almost as soon as plucked, and
transferred to a special receptacle in the stomach. From
this it is regurgitated into the mouth by a reversed action
of the muscles of the throat, and, after having undergone
mastication,—or rumination—is transferred to the digesting
part of the stomach. Now, it is evident that this compli-
cated arrangement, so different from that of other animals,
must be of some special advantage to the ruminants. As
a matter of fact, these animals, like other large herbivores,
are obliged to consume a vast quantity of food to obtain
sufficient nutriment; and itis obvious that if this food had
to be masticated as soon as plucked, the operation of
feeding would be very protracted; but by the arrangement
mentioned the requisite amount of food can be gathered
within a comparatively short time, and the animals can then
retire to ruminate in concealment. It is superfluous to
comment on the advantage of this arrangement to creatures
which, like many ruminants, have but little means of
defending themselves against carnivorous foes; but we
may mention that many still further increase this advantage
by feeding only at dawn or evening, when they are far
less conspicuous than in the mid-day glare. There is,
moreover, evidence that when ruminants first appeared,
this rapid feeding was of more importance than at the
present day, since while many of the modern larger forms,
like oxen, antelopes, and deer, are provided with formidable
weapons in the shape of horns or antlers with which they
can keep foes at bay, in earlier times such weapons were
either absent or but feebly developed.

Seeing, then, that the function of rumination is
correlated with a special compartment of the stomach for
the temporary reception of the freshly-gathered food, it
would be expected that animals thus provided would also
possess an efficient masticating arrangement for reducing
their food to the condition in which it yields the fullest
nutriment. Such, indeed, is the case, the grinding-teeth

78 RUMINANTS AND THEIR DISTRIBUTION.

of ruminants being of a complex structure, unknown
elsewhere ; the last three of these teeth in the upper Jaw
(Fig. 26) being composed of four columns, of varying
height, of which the two inner ones
are crescent-shaped; such a type of
tooth being termed selenodont. The
lower grinding-teeth having their
crescents directed the opposite way to
those of the upper jaw, and both
upper and lower teeth consisting of
layers of different hardness, we can
scarcely imagine a better masticating
machine than is presented by the
opposition of the two series of
erinding - teeth of these animals.
Bearing in mind this structure, the
definition of cud-chewing, selenodont
mammals will suffice to distinguish
the ruminants from all other animals.
When, however, we say that these characteristics dis-
tinguish them from all other mammals it must be added
that this refers only to those of the present day, for a
transition can be traced through extinct forms to the more
simply constructed orinding-teeth of the swine. We have
already seen how the Mosaic law recognized the similarity
in the structure of the hoofs of the ruminants and the
swine, and it is curious that while under the Cuvierian
system of zoology these two groups were widely sundered,
modern paleontological researches have shown that they
are really closely related, the want of the power of chewing
the cud, with the correlated absence of the selenodont
structure of the teeth, being the chief essential features
in which the latter differ from the former.

Here a curious problem is presented to those who put
their faith im a mode of evolution dependent only upon
so-called natural causes, in that it’is impossible to give
any adequate explanation of what advantage would be the
development of an incipient selenodont structure in the
teeth of the early swine-like ungulates, or at what precise
stage the function of chewing the cud, with the con-

Fic. 26.—A left
Upper Cheek-Tooth of
an Antelope.

STRUCTURE OF FEET.

79

comitant development of a separate compartment in the
stomach, was superadded to the normal mode of feeding

characteristic of the swine.

Here we must say a few words as to the structure of

the ruminant foot. The “cloven
hoof” of ruminants and swine has
become such a proverbial expression
that the idea may still linger that
this is due to the fission of a single
hoof, like that of a horse. Nothing
could, bowever, be further from the
truth ; the two hoofs of a ruminant
(Fig. 27) corresponding to the
terminal joints of our own middle
and ring-fingers (or the correspond-
ing toes), which are the third and
fourth of the typical series of five.
The lateral or spurious hoofs (not
shown in Fig. 27) of the ruminants
represent our own index (second)
and little (fifth) fingers, or toes. It
is a further peculiarity of the true
ruminants and camels that the two
separate bones which in the swine
connect the two large digits with
the wrist or ankle are fused into a
single cannon-bone (Fig. 27); the
primary dual origin of which is
indicated by the two distinct pulley-
like surfaces at the lower end,
which carry the bones of the digits.
The peculiar little ruminants known
as the chevrotains—of which more
anon—retain, however, evidences of
their kinship with the swine, in
that some of them have the two
elements of the front cannon-bone
—or metacarpals as they are then
called—quite separate from one
another. Indeed, in the same

Fic. 27.—Bones of the
Hind Foot of a Rumi-
nant. The letters 1
dicate the lower bones

of the ankle.
Osborn.)

(After

80 RUMINANTS AND THEIR DISTRIBUTION.

manner as we may trace a transition from the selenodont
tecth of the ruminants to the bunodont ones of the swine,
we may mark how the two-toed and cannon-boned
ruminants passed into swine-like animals with four toes
supported by as many separate metacarpal bones.

Having now mentioned the leading characters of a
modern ruminant, as distinct from other mammals, we
may refer toa peculiarity, which, although by no means
characteristic of all, is a striking one, and one sharply
differentiating the group from all others. This is the
tendency to the development of appendages on the skull,
arranged ina pair at right angles to its longer axis, and
taking the form either of solid branching antlers, as in the
deer, or of hollow sheaths of horn covering bony cores on
the skull, as in the oxen and antelopes.

Passing to the consideration of the various kinds of cud-
chewing mammals, we find that the true ruminants, or
those with hoofs, no upper front teeth, and a cannon-bonc
in both limbs, arrange themselves in several minor groups.
The most important to man are the “ hollow-horned
ruminants,” such as oxen, sheep, goats, and antelopes, all
of which are characterized by the presence of horns, at
least in the males. The vanety of form assumed by the
horns renders this group one of the most attractive of all
animals; and we have but to recall the curved and smooth
horns of the oxen, the equally massive but wrinkled ones
of the wild sheep, those of the ibex with their knotted
points and scimitar-hke backward sweep, the spear-like
form of those of the gemsbok, and the spiral twist of those
of the kudu and eland, to realize the variety of contour
assumed by these appendages.

The oxen (including bison and buffaloes) are, with the
exception of the American bison, Old World types, and
were formerly abundant in Europe, where, however, they
are now only represented by the bison preserved in the
forests of Lithuania and the Caucasus, and by the half-
wild cattle of Chillingham and some other British parks,
which have been thought to be the direct descendants of
the British wild ox, or aurochs, of Csesar’s time, but are
more probably derived from ancient domesticated breeds

SHEEP, GOATS, AND ANTELOPES. 81

which have reverted to a nearly wild state. True wild
oxen now exist only in India and the adjacent regions,
while wild buffalo occur both in India and Africa.

Equally characteristic of the Old World are wild sheep
and goats, the “big-horn” being an outlying North
American type. Both groups are essentially mountain
animals, the head-quarters of the former being the high-
lands of Central Asia, while on the southern flanks of the
same mountain-barrier the latter are more abundant.
Both are also represented in the mountains of Europe; but
in peninsular India there is but the wild goat of the
Nilgiries, while in the whole of Africa we have only the
wild sheep of Barbary and the ibex of Abyssinia. This
absence of sheep and goats from Africa may, perhaps, be
due to the fact that these animals are of comparatively late
origin, and were probably poorly represented at the time
when the other ruminants entered that continent from the
north. The musk-ox of Arctic America is an aberrant
form allied to the sheep.

The antelopes have a distribution nearly the reverse of
that of the sheep and goats, the great majority being
restricted to Africa, where there are probably fully ninety
species, against about a score in all the rest of the world,
except Arabia and Syria, of which the fauna is allied to
that of Africa. Indeed, the only typical antelopes found
beyond these regions are the black-buck, the nilgai, the
four-horned antelope of India, the saiga of Tartary, the
chiru of Tibet, and several members of the widely dis-
tributed gazelles. The rings marking the horns of the
latter (Fig. 28) and many other antelopes are very distinc-
tive of the group, although by no means universal. The
European chamois, the goat-antelopes of India and China,
andthe Rocky Mountain goat of America, serve to connect
the typical antelopes with the goats, and it is these alone
which represent the group in Europe, to the eastward of
India, and in North America. Seeing that in Tertiary
times, antelopes of African types occurred in southern
Europe and India, it is difficult to determine why the
group should have so dwindled or disappeared there ;
although we can readily account for their extraordinary

G

82 RUMINANTS AND THEIR DISTRIBUTION.

development when they once obtained an entry into Africa,
on account of the immense area open to them, in which
there was no competition by any other ruminants except
butfaloes and giraffes.

To the zoologist Africa is indeed a
country characterized by the number
of animals living there which have
disappeared from other regions ; and
there is no better instance of this
survival than the giraffe, a ruminant
that, as regards its cranial appendages,
stands midway between the hollow-
horned group and the deer.* Weare
all familiar with the ungainly and yet
beautiful form of the giraffe ; but it is
probably less well known that giraffes
once roamed over Greece, Persia,
India, and China, where, as in Africa
at the present day, they were accom-
panied by ostriches and hippopotami.
And here again we are confronted by
the problem how to account for the
disappearance from regionsapparently
exactly suited to their habits, of all
these animals. The giraffe is, how- p14 98 Horns of
ever, not only the sole survivor of Gazelle. (From
several extinct species of its own Giinther.)
kind, but it likewise represents a lost
group of ruminants, intermediate between the horned and
antlered Old World types. The head-quarters of this
group was India, where, among other forms, occurs the
gigantic sivathere, rivalling the elephant in bulk, and
characterized by its two pairs of horns (Fig. 29), of
which the hindmost were branching and _antler-hke,
although apparently never shed, and probably covered
during life with skin and hair.

If our attention has been turned to Africa as the head-
quarters of antelopes and giraffes, it must be directed to

* See the following chapter.

DEER. 83

other regions when we come to the deer, since, with the
exception of the Barbary stag, there is no representative of
the group in all that continent. With few exceptions, deer
are characterized by the antlers of the males, the reindeer
alone having these appendages in both sexes. They are
the only true ruminants found in South America, where
many of the species have comparatively simple antlers, and
thus show affinity with the early fossil types, some of
which were antlerless. Allied species range through North
America, but it is not till the north of that continent is
reached that we find in the wapiti a representative of our
own red deer. The red deer group extends through Europe

Fie. 29.—Skull of Sivathere, from the Pliocene of India.

and a large part of Central Asia, but in India and the
Malayan region it is replaced by the rusine deer, like the
sambar, in which the antlers (Fig. 30, a) lack the bez-tine
of the red deer (ibid, b). Other marked varieties of antler
are exhibited by the elk, the fallow deer, and the reindeer;
but none of these approach those of the extinct Trish deer
(Fig. 25), which may have an eleven feet span from tip to

@2

84 RUMINANTS AND THEIR DISTRIBUTION.

tip. It is noteworthy that in a few small deer in which
the males have no antlers, they are compensated by having
long tusks in the upper Jaw.

The tiny orien-
tal chevrotains,
and the larger
African water-
chevrotain form
a group quite dis-
tinct from all the
above, and are
in some respects
related to the
swine. None of
them have ant-
lers, and the
African — species
is the only living
ruminant in
which the two
elements of the
front cannon-
bone remain
separate, thus
affording another
instance of the Fre. 30.—Antlers of Red (A) and Sambar (B)

survival of primi- Deer. a brow-, 6 bez-, c trez-tine, d e sur-
tive forms in royals. (After Blanford.)
Africa.

Lastly, we have the group of camels and llamas, which
differ from other ruminants in that their feet form cushion-
like pads, while their upper jaws possess front teeth.
According to the latest researches it 1s considered probable
that this group has diverged from primitive swine-like
animals quite independently of the true ruminants, an
inference which is very remarkable, showing that selenodont
teeth, a complex stomach, the function of rumination, and
the single cannon-bone, have been acquired quite inde-
pendently in the two groups. The present distribution
of camels and llamas is remarkable, the former being

CAMELS AND LLAMAS. 85

confined to Africa and Asia, and the latter to South
America. Here, however, geology comes to our aid, for
in former times camel-like ruminants were abundant in
North America, while the fossil camels of India show
certain resemblances to the llamas, and we can thus
understand how the present distribution of the two
sections of the group has come about. With the possible
exception of some herds of the Bactrian species in Central
Asia, which are, however, probably descended from
individuals escaped from captivity, wild camels are now
unknown, and we cannot even determine the original
habitat of the single-humped species.

Thus ends our brief survey of the chief groups of living
ruminants and their distribution. Did space permit, we
might go on to refer to their extreme importance to man,
both as sources of food and of clothing, and as beasts of
draught and burden, but having reached our limits, we
trust that we may have aroused in our readers an interest
in these highly specialized animals which may induce
some of them to devote further consideration to the
subject.

86 THE TALLEST MAMMAL.

CHAPTER IX.

THE TALLEST MAMMAL.

Comparep with their extinct allies of earlier periods of the
earth’s history, it may be laid down as a general rule that
the large animals of the present day are decidedly inferior
in point of size. During the later portion of the Tertiary
period, for instance, before the incoming of the glacial epoch,
when mammals appear to have attained their maximum
development, there lived elephants alongside of which
ordinary individuals of the existing species would have
looked almost dwarfs, while the cave-bear and the cave-
hyzna attained considerably larger dimensions than their
living representatives, and some of the sabre-toothed tigers
must have been decidedly larger than the biggest African
lion or Bengal tiger. Again, the remains of red deer, bison,
and wild oxen, disinterred from the cavern and other super-
ticial deposits of this country, indicate animals far superior
in size to their degenerate descendants of the present day ;
while some of the extinct pigs from the Siwalik Hills of
northern India might be compared in stature to a tapir
rather than to an ordinary wild boar. The same story is
told by reptiles, the giant tortoise of the Siwalik Hills, in
spite of its dimensions having been considerably exaggerated,
greatly exceeding in size the largest living giant tortoises
of either the Mascarene or the Galapagos Islands. The
Siwalik rocks have also yielded the remains of a long-
snouted crocodile, allied to the garial of the Ganges,
which probably measured from fifty to sixty feet in length,
whereas it is very doubtful if any existing member of the
order exceeds half the former of these dimensions. If,
moreover, we took into account totally extinct types, such
as the megatheres and mylodons of South America, and
contrasted them with their nearest living allies—in this
instance the sloths and anteaters—the discrepancy in size
would be still more marked, but such a comparison would
scarcely be analogous to the above.

Fig. 31.—The Giraffe.

88 THE TALLEST MAMMAL.

To every rule there is, however, an exception, and there
are a few groups of living large mammals whose existing
members appear never to have been surpassed in size by
their fossil relatives. Foremost among these are the
whales, which, as we have seen in a previous chapter, now
appear to include the largest members of the order which
have ever existed. The so-called white, or square-mouthed,
rhinoceros of South Africa seems also to be fully equal in
size to any of its extinct ancestors; and the same is
certainly true of the giraffe, which may even exceed all its
predecessors in this respect. Whether, however, the fossil
giraffes, of which more anon, were or were not the equals
in height of the largest individuals of the living species,
there is no question but that the latter is by far the tallest
of all living mammals, and that it was only rivalled in this
respect among extinct forms by its aforesaid ancestors.
Moreover, if we exclude creatures like some of the gigantic
dinosaurian reptiles of the Secondary epoch, which, so to
speak, gained an unfair advantage as regards height by
sitting up on their hind legs in a kangaroo-like manner,
and limit our comparison to such as walk on all four feet
in the good old-fashioned way, we shall find that giraffes
are not only the tallest mammals, but likewise the tallest
of all animals that have ever existed.

In the great majority of animals that have managed to
exceed all their kin in height, the increment in stature has
been arrived at by lengthening the hind limbs alone, and
thus making them the sole or chief support of the body.
In some of these cases, as among the living kangaroos
and the extinct dinosaurs, the body was raised into a more
or less nearly vertical position, and the required height
attained without any marked elongation of the neck. In
birds, on the other hand, like the ostrich, the body is
carried in nearly the same horizontal position as in a
quadruped, but both the hind legs and the neck have been
elongated. The giraffe, however, has attained its towering
stature without any such important departure from the
general structure characterizing its nearest allies, and thus
preserves all the essential features of an ordinary quad-
ruped. Belonging, as we have had occasion to mention

STRUCTURE AND HEIGHT. 89

in the preceding chapter, to the great group of ruminant
ungulates, among which it is the sole living representative
of a separate family, the giraffe owes its height mainly to
the enormous elongation of two of the bones of the legs,
coupled with a corresponding lengthening of the vertebre
of the neck. As in all its kindred, the lower segment of
each leg of this animal forms a cannon-bone, the nature
of which has been explained in the same chapter; and
in the fore limb it is the bone below the wrist (com-
monly termed the knee), and the radius above the latter,
which have undergone an elongation so extraordinary as
to make them quite unlike, as regards proportion, the
corresponding elements in the skeleton of a ruminant,
such as an ox, although retaining precisely the same
structure. Similarly, in the hinder limb, it is the cannon-
bone below the ankle joint or hock, and the tibia or shin-
bone above, which have been thus elongated. To anyone
unacquainted with their anatomy, it might well appear
that a giraffe and a hippopotamus would differ greatly
in regard to the number of vertebre in their necks; but,
nevertheless, both conform in this respect to the ordinary
mammalian type, possessing only seven of such segments.
Whereas, however, those of the latter animal are very
broad and short, in the giraffe they are extremely long and
slender, attaining in full-grown individuals a length of
some ten inches. This remarkable adherence to one
numerical type in the neck vertebre is, indeed, a very
curious feature among mammals; the extreme contrasts
in respect of form being exhibited by those of the Green-
land whale, in which each vertebra is shortened to a broad
disc-like shape, and the giraffe, where it is equally narrow
and elongated.

As regards the height attained by the male of the tallest
of quadrupeds, there is, unfortunately, a lack of accurate
information, and since it is probable that the majority of
those now living are inferior in size to the largest
individuals which existed when the species was far more
numerous than at present, it is to be feared that this
deficiency in our knowledge is not very likely to be
remedied. By some writers the height of the male giraffe

20 THE TALLEST MAMMAL.

is given at sixteen feet, and that of the female at fourteen
feet, but this is certainly below the reality. For instance,
Mr. H. A. Bryden states that a female he shot in southern
Africa measured nearly seventeen feet to the summits
of the horns, while a male measured within less than
half an inch of nineteen feet; Sir S. Baker, whose
experiences are derived from the north-eastern portion
of the continent, also asserting that a male will reach as
much as nineteen feet. From the evidence of a very
large, though badly preserved specimen in the Natural
History Museum, it may also be inferred that fine males
certainly reach the imposing height of over eighteen
feet.

Although this towering stature is the most obvious
external feature of the giraffe, it is not one which would
of itself justify the naturalist in classing the animal as the
representative of a family apart from other ruminants ;
and we must accordingly inquire on what grounds such
separation is made. On the whole, the most distinctive
structural peculiarity of the giraffe is to be found in the
nature of its horns. These, as mentioned in the preceding
chapter, are quite unlike those of any other living
ruminant, and take the form of a pair of upright bony
projections arising from the summit of the head in
both sexes, and completely covered during life with skin.
In the immature condition separate from the skull, these
horns become in the adult firmly attached to the latter;
while below them, in the middle of the forehead, is another
lower and broader protuberance, sometimes spoken of as a
third horn. Obviously, these horns—for want of a better
name—are quite unlike the true horns of the oxen and
antelopes, or the antlers of the deer; and this essential
difference in their structure is alone quite sufficient to
justify the reference of the giraffe to a family all by itself.
When, however, we come to inquire whether the creature
is more nearly akin to the deer or to the hollow-horned
ruminants (as the oxen, antelopes, and their allies
are termed), we have a task of considerable difficulty.
Relying mainly on the structure of its skull, and its
low-crowned grinding teeth, which are invested with

EXTERNAL FORM. 91

a peculiar rugose enamel having much the appearance of
the skin of the common black slug, some naturalists
speak of the giraffe as a greatly modified deer. A certain
justification for this view is, indeed, to be found in the
circumstance that the liver of the giraffe, like that of the
deer, is usually devoid of a gall-bladder. Occasionally,
however, that appendage, which is so characteristic of the
hollow-horned ruminants, makes its appearance in the
giraffe, thus showing that no great importance can be
attached to it one way or another. On the other hand, in
certain parts of its soft anatomy, the creature under con-
sideration comes very much closer to the antelopes and
their kin than to the deer. It would appear, therefore, on
the whole, that the giraffe occupies a position midway
between the deer on the one hand and the antelopes on
the other ; while as neither of these three groups can be
regarded as the direct descendant of either of the other
two, it is clear that we must regard all three as divergent
branches from some ancient common stock.

In general appearance, the giraffe is too well known
to require description, but attention may be directed
to a few of its more striking external peculiarities. One
remarkable feature is the total lack of the small lateral
or spurious hoofs, which are present in the great majority
of ruminants, and attain relatively large dimensions
in the reindeer and musk-deer. Indeed, the only other
members of the whole group iv which these hoofs are
absent are certain antelopes; but this absence cannot
be taken as an indication of any affinity between the
latter and the giraffe, since it is most probably the result
of independent development. Equally noticeable are the
large size and prominence of the liquid eyes, and the great
length of the extensile tongue; the former being obviously
designed to give the creature the greatest possible range
of vision, while the extensibility of the latter enhances the
capability of reaching the foliage of tall trees afforded by
the lengthened limbs and neck. In comparison with the
slenderness of the neck, the head of the giraffe appears of
relatively large size; but this bulk, which is probably
necessary to the proper working of the long tongue, is

92 THE TALLEST MAMMAL.

compensated by the extreme lightness and porous structure
of the bones of the skull. Lastly, we may note that the
long tail, terminating in a large tuft of black hairs, is a
feature unlike any of the deer, although recalling certain
of the antelopes.

Somewhat stiff and ungainly in its motions—the small
number of vertebre not admitting of the graceful arching
of the neck characterizing the swan and ostrich—the
giraffe is in all parts of its organization admirably adapted
to a life on open plains dotted over with tall trees, upon
which it can browse without fear of competition by any
other living creature. Its wide range of vision affords it
timely warning of the approach of foes; from the effect of
sand-storms it is protected by the power of automatically
closing its nostrils; while its capacity of existing for
months at a time without drinking renders it suited to
inhabit waterless districts like the northern part of the
great Kalahari desert. And here we may mention in
passing that the camel has gained a reputation for being
adapted for a desert-life above all its allies which is not
altogether deserved. It is true, indeed, that a camel can
and does make long desert journeys, but these can only be
maintained during such time as the supply of water in its
specially constructed stomach holds out, and when this
fails there is not an animal that sooner knocks up alto-
gether than the so-called ‘ship of the desert.” Did their
bodily conformation and general habits adinit of their being
so employed, there can indeed be little doubt that the
giraffe and some of the larger African antelopes, which are
likewise independent of water, would form far more useful
and satisfactory beasts of burden for desert travelling than
the, to our mind, somewhat over-rated camel. Returning
from this digression, it must be mentioned that when
we speak of the giraffe being independent of water, we
by no means intend to imply that it never drinks. On
the contrary, during the summer this ruminant, when
opportunity offers, will drink long and frequently; but
it is certain that for more than half the year, in
many parts of southern Africa at least, it never takes
water at all. In certain districts, as in the northern

DISTRIBUTION. 93

Kalahari, this abstinence is, from the nature of the country,
involuntary ; but according to Mr. Bryden, the giraffes
living in the neighbourhood of the Botletli river—their
only source of water—never drink therefrom throughout
the spring and winter months. When a giraffe does drink,
unless it wades into the stream, it is compelled to straddle
its fore-legs far apart in order to bring down its lips to the
required level, and the same ungainly attitude is perforce
assumed on the rare occasions when it grazes.

There is yet one other point to be mentioned in con-
nection with the adaptation of the giraffe to its surroundings
before passing on, and this relates to its coloration.
When seen within the enclosures of a menagerie—
where, by the way, their pallid hue gives but a faint
idea of the deep chestnut tinge of the dark blotches on the
coat of a wild male—the dappled hide of a giraffe appears
conspicuous in the extreme. We are told, however, that
among the tall kameel-dhorn trees, or giraffe-mimosas,
on which they almost exclusively feed, giraffes are the
most inconspicuous of all animals; their mottled coats
harmonizing so exactly with the weather-beaten stems and
with the splashes of light and shade thrown on the ground
by the sun shining through the leaves, that at a com-
paratively short distance even the Bushman or Kaffr is
frequently at a total loss to distinguish trees from giraffes,
or giraffes from trees.

At the present day, it is hardly necessary to mention, the
single species of giraffe is exclusively confined to Africa,
not even ranging into Syria, where so many other species
of animals otherwise characteristic of that continent are
found. This restricted distribution was, however, by no
means always characteristic of the genus; for during the
Pliocene period extinct species of these beautiful animals
roamed over certain parts of southern Europe and Asia. The
first of these extinct giraffes was discovered by Falconer and
Cautley many years ago in that marvellous mausoleum of
fossil animals, the Siwalik Hills of north-eastern India ;
remains of the same species bcing subsequently brought
to light in the equivalent deposits of Perim Island, in
the Gulf of Cambay, and likewiseinthe Punjab. A second

94, THE TALLEST MAMMAL.

species has also left its remains in the newer Tertiary rocks
of Pikermi, near Athens ; while those of a third have been
disinterred in China, and a fourth in Persia. It was,
indeed, believed for a long time that France also was once
the home of a member of the genus, but the specimen on
which the determination was based is now known to be a
jaw-bone belonging to the existing species. Although we
are, unfortunately, unacquainted with the geology of the
greater part of Africa, the foregoing evidence points
strongly to the conclusion that giraffes (together with
ostriches, hippopotami, and certain peculiar antelopes) are
comparatively recent emigrants into that continent from
the north-east ; but,as we have previously had occasion to
mention, the reason why all these animals have totally
died out in their ancient homes is still one of the darkest
of enigmas.

Unknown in the countries to the north of the Sahara,
as well as in the great forest regions of the west, which
are unsuitable to its habits, the giraffe at the present day
ranges from the north Kalahari and northern Bechuana-
land in the south, through such portions of eastern and
central Africa as are suited to its mode of life, to the
southern Sudan in the north. Unhappily, however, this
noble animal is almost daily diminishing in numbers
throughout a large area of southern and eastern Africa,
and its distributional area as steadily shrinking. Whether
it was ever found to the south of the Orange river and in
the Cape Colony may be a moot point, although, according
to Mr. Bryden, there are traditions that it once occurred
there. Apart from this, it is definitely known that about
the year 1813 these animals were met with only a
little to the north of the last-named river; while as
late as 1886 they were still common throughout the
Transvaal, and more especially near the junction of the
Marico with the Limpopo river. Now their last refuges
in these districts are the extreme eastern border of
the Transvaal (where only a few remain), and the district
lying to the north of Bechuanaland and known as Khama’s
‘country, or Bawangwato, together with the northern
Kalahari. Even here, however, their existence ig

ITS GROWING SCARCITY. 95

threatened, as there isa proposal to put down tube-wells in
the waterless Kalahari, which, if successfully accomplished,
will open up the one great remaining stronghold of the
animal to the merciless hunter. Unless, therefore, efficient
and prompt measures are taken for its protection, there is
but too much reason to fear that the giraffe will ere long
be practically exterminated from this part of Africa ;
although, fortunately, it has a prospect of surviving for
many years to come in the Sudan and Kordofan. The
great majority of the giraffes killed at the present day in
southern Africa are shot solely for the sake of their skins,
which are now, owing to the practical extermination of
rhinoceroses south of the Zambesi, and the ever-increasing
scarcity of the hippopotamus, used in the manufacture of
the formidable South African whips known as jaimboks.
The value of a skin usually varies, according to size and
quality, from £2 10s. to £4, although they have been
known to fetch £5 apiece; and it is for the sake of such
paltry sums that one of the noblest and most strange of
mammals stands in imminent danger of extermination !

We may conclude this notice by mentioning that although
the giraffe was familiar to the Romans of the time of the
empire, by whom it was known as the camelopard, it
appears to have been almost completely lost sight of in
Europe in later times till the closing decades of the
eighteenth century, although a single example is stated to
have been exhibited alive in Florence some four centuries
ago. With that exception, it seems to have been generally
regarded as a fabulous animal until one was shot near the
Orange river in 1777 by an Englishman, and another by
the French naturalist, Le Vaillant, in 1784. From that
time onwards our knowledge of the animal and its habits
gradually increased, although it was not till the spring of
1886 that four living specimens from the Sudan were
brought alive to London, where some of their descendants
lived continuously till 1892, since which date the species
has been unrepresented in the Regent’s Park.

96 LEMURS.

CHAPTER X.
LEMURS.

In a previous chapter we have had occasion to refer to
Africa as an archaic kind of land containing types of
mammalian life which, while formerly widely spread over
the Old World, are now restricted to that continent. If
this preservation of ancient types be highly characteristic
of continental Africa, still more markedly is it so of the
large island of Madagascar, lying off its eastern coast.
In Africa itself many of the ancient types are more or less
closely allied to other living mammals, and most of them
belong to orders which are abundantly represented in
other parts of the world. Very different is, however, the
case with Madagascar, of which the great peculiarity is
that it has preserved to us a whole fauna of those remark-
able animals known as lemurs, which are represented else-
where only in Africa and the Oriental region, and there by
a comparatively small number of species belonging to
genera totally distinct from those found in Madagascar.
To put the matter more clearly, it may be stated that out
of a total of thirteen genera of living lemurs no less than
eight are absolutely confined to the island of Madagascar,
while the remaining five are distributed over Africa, India,
and the Malayan islands; two out of the five being
African, one Indian, and two Malayan. The disproportion
is, however, not even adequately expressed by the above
statement, since, while most of the Malagasy genera are
represented by a considerable number of species, of those
found in other regions only one has more than two species,
while two out of the other four have but a single species
each. Lemurs are, indeed, in every sense the characteristic
mammals of Madagascar, being far more common in its
woods and coppices than are squirrels in those of this
country. So common are they said to be in certain parts
of the island that, according to the French traveller,

THEIR DISTRIBUTION. 97

M. Grandidier, it is impossible to beat through a single
copse without turning out at least one of these strange
creatures.

In order to arrive at the true reason of the present dis-
tribution of any group of animals, it is always necessary to
consult the records of geology; and it appears from these
that while lemurs were unknown both in Europe and
North America during the Pliocene and Miocene divisions
of the Tertiary period, when we reach the upper part of
the Eocene epoch we find their remains occurring in
company with those of the extinct anoplotheres and
paleotheres, or other allied animals, in both the eastern
and western continents. It is, however, hardly necessary
to observe that the whole of these early lemurs belonged
to genera which are quite distinct from any of those living
at the present day, although one of them appears to have
nearly been allied to the African group.

The discovery of these extinct lemurs, which is but com-
paratively modern, at once reveals the fact that this group
of animals is a very ancient one, and one formerly widely
spread over the globe, and represented by at least one
species in our own island. Not many years ago it was
sought to explain the present peculiar distribution of
lemurs by the supposition that a large island or continent
formerly existed in the Indian Ocean; and the name
Lemuria was suggested, appropriately enough, for this
hypothetical land. From this presumed ancestral home
it was considered that the lemurs had spread on all sides,
some to find a refuge in the Malayan islands, others in
the forests of Ceylon and southern India, but the larger
number in Madagascar and Africa. Unfortunately, how-
ever, for a very pretty theory, the geologists had a word
to say on the matter; and this word was to the effect that
Lemuria could not possibly have existed at the time its
presence was required for the needs of the theory.

With our fuller knowledge of fossil lemurs any such
hypothetical land is, however, quite unnecessary to explain
the present distribution of the group. At or about the
time these animals existed in Europe there is little doubt
that they were also spread over Africa, which there is

H

98 LEMURS.

good evidence to show was formerly connected by land
with Madagascar. We do not, indeed, yet know how the
ancient lemurs of Europe got into Africa, but when once
there it is certain that they were ultimately cut off from
Europe by a sea which stretched from the Atlantic to the
Bay of Bengal in upper Eocene times. For some time
afterwards, during which Africa and Madagascar still had
a free communication, the large mammals characteristic
of Miocene Europe were unknown in the lands to the south
of this great sea, where lemurs and other lowly animals
flourished in security. During some portion of this period
Madagascar must have become separated from Africa,
while an upheaval of land once more brought Africa into
connection with Europe and Asia, and thus allowed it to
be overrun by the great hoofed and carnivorous mammals
which had hitherto existed only to the north of the
dividing sea. This incursion of large quadrupeds at once
put a final stop to the supremacy of the lemurs in Africa,
where only a few species have since managed to survive
by the aid of their nocturnal habits. In Madagascar,
however, where there are still no large quadrupeds, and
where the only carnivores are certain civet-like animals,
the lemurs have continued to flourish in full exuberance,
and the existing state of that island thus offers to our
view a picture of what must have been the condition of
Africa previous to the advent of its present fauna from
the north. The few lemurs now inhabiting the Indian and
Malayan region are, doubtless, also survivors from the
original central home of the group, which have found
safety in the dense forests of the regions they inhabit.

A good deal more might be said on the subject of the
past and present distribution of lemurs, but by this time
the reader will probably be impatient to know something
of the characteristics of the animals thus designated by
naturalists. Of course comparatively little can be said on
this subject in an essay of the present length, and it
unfortunately happens that the lemurs, as a whole, do not
present any very strongly marked single external feature
by which they can be distinguished at a glance from all
other mammals. It is, however, only with some of the

CHARACTERISTICS. 99

lower monkeys of the New World that they could possibly
be confounded by observant persons (although we have
heard of some members of the family being mistaken for
sloths) ; but the distinct geographical distribution of the
two groups renders it improbable that any confusion is
likely to arise between them. The nearest relations of the
lemurs are undoubtedly the monkeys, and most naturalists
in this country are now agreed in regarding the former as

EN
\

\

Fia. 32.—The Slender Loris, in waking and sleeping postures, with
figures of the arm and leg. (From Sir J. E. Tennent.)*

representing a primitive group of the order (Primates)
which includes the latter. Lemurs may always be dis-
tinguished from monkeys and apes by certain features in
their skulls, as well as by several peculiarities in their

* We are indebted to Messrs. Longmans for the use of this figure.

H2

100 LEMURS.

internal structure ; but as these require a certain amount
of anatomical knowledge for their proper comprehension,
we must ask our readers to take it on trust that such
differences do exist. Externally, lemurs differ from ordi-
nary monkeys by their more or less fox-like and immobile
countenances, but since the marmosets of South America
(which are a lowly type of monkey) resemble them in
this respect, this character does not afford an absolute
distinction between the two groups. All lemurs are
further characterized by having the second toe terminating
in a long pointed claw, as shown in the right hand lower
figure of our first illustration, whereas in ordinary monkeys
the same toe has a flattened nail. Unfortunately, how-
ever, the marmosets have also a pointed claw on the toe in
question, so that this character does not afford an absolute
point of distinction between the two. On examining the
upper teeth of the lemurs it will, however, be found that,
except in the aye-aye of Madagascar, the first pair of
incisor or front teeth are separated from one another in
the middle line by a distinct gap, whereas in all monkeys
they are, as in ourselves, in contact. Now as the aye-aye
differs from all monkeys in having its first upper incisors
of the chisel-like form characteristic of rodents (rats,
beavers, &c.), the upper front teeth of the lemurs will
serve to distinguish them absolutely from the whole of
the monkeys.

In appearance the various kinds of lemurs differ greatly
from one another, some of them looking not unlike
monkeys; while others, as the one represented in Fig. 32,
are characterized by their long and slender limbs, enormous
eyes, and general ghostly form. Then, again, while some
of them are furnished with long tails, otbers are destitute
of these appendages; and the common cat-lemur of
Madagascar is distinguished from all the rest by the bold
alternating rings of black and white with which the tail is
ornamented. The last-named species is further peculiar in
living chiefly among rocks, whereas the others are arboreal
and mainly nocturnal in their habits. It is from these
nocturnal habits, coupled with the large eyes, ghostly
appearance, and stealthy movements, characteristic of

HABITS, ETC. 101

many of the species, that Linnzus was induced to propose
the name of lemurs (from the Latin term for evil spirits)
for this group of animals—a name which, in the absence of
any vernacular title, has been adopted as their ordinary
designation.

None of the lemurs are of large size, the length of the
head and body in the largest species being only about two
feet, and some of them are not larger than rats. They are
all excellent climbers, and the majority spend the day sleep-
ing either in the hole of a tree, in a specially constructed
nest, or rolled up in a ball after the manner shown in our
first illustration. Their food consists of leaves and fruits,
birds and the eggs, reptiles and insects, and occasionally
honey or sugar-cane ; and most of them spend the whole of
their time im trees, rarely, if ever, descending to the
ground. Some of the larger species inhabiting Madagascar
are, however, an exception in this respect, as well as in
their diurnal habits, and they may sometimes be observed
in numbers jumping across the plains from wood to wood
in their own peculiar fashion, when it is necessary to seek
fresh food. From the structure of their brains and other
parts of their organization, it is evident that the lemurs
hold a very low place in the mammalian class, although
their near relatives, the monkeys and apes, occupy the
highest position. It is probable, indeed, that the modern
lemurs are the descendants of the ancient ancestral stock
from which monkeys have originated, and since they them-
selves are also nearly related to the so-called insectivores
(shrews, moles, hedgehogs, &c.), while the latter may have
been directly descended from marsupials (opossums, &c.\,
we see how close is the connection between the very
highest and the very lowest representatives of the
mammalian class. The low position of the lemurs in
the zoological scale is in harmony with their antiquity
and their peculiar geographical distribution, and it is note-
worthy that both in Madagascar and in Africa lemurs are
accompanied by certain insectivores of a very low degree
of organization, and unlike those found in any other part
of the world.

The limits of this essay render our notice of the various

102 LEMURS.

kinds of lemurs necessarily very brief, and our chief
attention will accordingly be directed to some of the more
peculiar and interesting forms. Among the Madagascar
lemurs are included a group known as indris, or, in the
vernacular, sifakas, and containing the largest of all these
animals. These sifakas are distinguished by the circum-
stance that all the toes of the foot, except the first, are
united together at their bases; and they are further
characterized by their parti-coloured fur, in which white,
black, and various shades of brown and orange predo-
minate. Most of them have long tails, but in one species
this appendage is represented by a mere stump. They
live in smail parties in the woods of Madagascar, and feed
entirely upon vegetable substances. By the aid of their
powerful limbs they are able to take enormous flying leaps
—sometimes as much as thirty feet in length—from tree
to tree, and when passing from one clump of trees to
another on the ground they hop on their hind limbs, with
their arms raised above their heads, in a series of ’short
jamps, when they are said to present the most ludicrous
and grotesque appearance. They are largely diurnal in
their habits, although sleeping during the heat of the
day.

The true lemurs, which are likewise confined to Mada-
gascar and some of the adjacent Comoro islands, differ
from the sifakas in having thirty-six in place of thirty
teeth, by their perfectly free toes, and their less elongated
hind limbs. They all have long tails, and the best known
species is the above-mentioned cat, or ring-tailed lemur,
easily recognized by the feature from which it derives its
second name. This animal, which is often exhibited in
menageries, is about the size of a domestic cat, and is
peculiar in frequenting rocks rather than trees, in at least
certain districtsin Madagascar. The black lemur, in which
the male is black and the female red, is a nearly allied
species ; and there are also several others. The females of
these lemurs have a peculiar habit of carrying their young
clinging to the under surface of their body, with the head
on one side and the tail on the other; but this strange
position is only maintained for a certain time, after which

GALAGOS AND SLOW-LEMURS. 103

the young creature mounts upon its parent’s back, where
it remains until able to shift for itself.

A third group is formed by the galagos, which differ
from the true lemurs in having two of the bones of the ankle
greatly elongated, so as to make this segment of the limb
much longer than ordinary. They all have long and bushy
tails, and are mostly of small size, some of them being
even smaller than a rat. The galagos are divided into two
groups—one confined to Madagascar and the other to
Africa. The former, or dormouse-lemurs, are peculiar in
that during the hot dry season several of the species
undergo a kind of hibernation, coiled up in the hollow of
some tree, and in order to prepare themselves for such a
protracted fast they accumulate on their bodies a large
store of fat. The true African galagos, in addition to
other features, differ from the last in that their large ears
are capable of being partially folded up, somewhat after
the fashion obtaining in the common long-eared bat. Like
the dormouse-lemurs, they are purely nocturnal, and when
on the ground they hop after the manner of kangaroos,
the elongation of the bones of the ankle doubtless sub-
serving this kind of movement.

Widely different from all the above are the curious slow-
lemurs of Asia and Africa, of which an Asiatic species is
represented in Fig. 32. These lemurs are characterized
by the index finger of the hand being either very short or
rudimentary, and likewise by their tail being similarly
abbreviated. The Asiatic representatives of this group,
of which there are two genera and about four species,
have the usual three joints to the index finger, which is,
however, extremely short, and no trace of a tail. It was
one of these lemurs which doubtless suggested to Linnzus
his name for the whole group, as their movements are slow
and deliberate in the extreme, their eyes large, and their
habits completely nocturnal. The Asiatic forms are known
by the name of loris. The common loris, with some allied
species, extends from Burma through the Malayan region
to Siam and Cochin China, and is a solitary animal
inhabiting the depths of the forests. The strange and
weird little animal represented in our first illustration is

104 LEMURS.

an inhabitant of southern India, and is commonly known
as the slender Joris. It differs from the common loris by
its much larger eyes, which are separated from one another
only by a very thin partition, as well as by its slender
body and limbs; and in consequence of these and other
points of difference is referred by naturalists to a distinct
genus, of which it is the sole representative. This beauti-
ful little creature is about the size of a squirrel, and is of
a yellowish-brown colour. It occurs in the forests, usually
in pairs. Sir E. Tennent observes that “the naturally
slow motion of its limbs enables the loris to approach its
prey so stealthily that it seizes birds before they can be
alarmed by its presenre. During the day, the one which
I kept was usually asleep in the strange position repre-
sented in the figure; its perch firmly grasped with both
hands, its back curved into a ball of soft fur, and its
head hidden deep between its legs. The singularly large
and intense eyes of the loris have attracted the attention
of the Singhalese, who capture the creature for the purpose
of extracting them as charms and love-potions, and they
are said to effect this by holding the little animal to the
fire till the eyeballs burst.” I once brought a pair of these
little creatures from Madras to Calcutta, and during the
voyage they lived chiefly on plantains and bread-and-milk.

In West Africa the slow lemurs are represented by the
potto and the smaller awantibo, both of which differ from
the loris by the reduction of the index finger to a mere
stump, and also by the presence of a distinct tail, which
is of greater length in the former than in the latter species.
These animals resemble their Asiatic cousins in their
habits, but are even more deliberate in their movements ;
and while the potto appears to be not uncommon, the
awantibo is of extreme rarity.

The whole of the preceding species are included by
naturalists in a single tamily, but the two following
representatives of the group are so different from all the
others that each is made the type of a distinct family. The
first of these two aberrant creatures is the weird tarsier, of
the forests of Sumatra, Borneo, Celebes, and some of the
Philippine islands. This animal derives its name from

TARSIER, 105

its greatly elongated ankle (tarsus), and is rather smaller
than an ordinary squirrel, with large ears, enormous eyes,
and a long tufted tail. Dr. Guillemard, who when in
Celebes was fortunate enough to obtain a living tarsier,
writes that ‘these little creatures, which are arboreal

Fie. 33.—The Tarsier. (From Guillemard’s ‘“ Cruise of the
Marchesa.” *

and of nocturnal habits, are about the size of a small rat,
and are covered with remarkably thick woolly fur, which
is very short. The tail is long and covered with hair at

* Messrs. Murray have kindly lent this figure.

106 LEMURS.

the root and tip, while the middle portion of it is nearly
bare. The eyes are enormous, and indeed seem, together
with the equally large ears, to constitute the greater part
of the face, for the nose and jaw are very small, and the
latter is set on, like that of a pug dog, almost at a right
angle. The hind limb at once attracts attention from the
great length of the tarsal bones, and the hand is equally
noticeable for its length, the curious claws with which it
is provided, and the extraordinary disc-shaped pulps on
the palmar surface of the fingers which probably enable
the animal to retain its bold in almost any position.
This weird-looking little creature we were unable to keep
long in captivity, for we could not get it to eat the
cockroaches which were almost the only food with which
we could supply it.”

Our brief account of the lemurs appropriately closes
with the strangest of them all—the now well-known aye-
aye of Madagascar. This remarkable animal, whose
systematic position was long a puzzle to naturalists, was
discovered as far back as 1780, but for eighty years after
that was only known in Europe by the single specimen
then obtained. The aye-aye differs from all other lemurs
in having but eighteen teeth, but its most marked
peculiarity is to be found in the circumstance that the
single pair of front or incisor teeth in each jaw have chisel-
shaped crowns like those of rats and beavers, and grow
continuously throughout the life of their owner. Another
peculiarity occurs in the extremely long and attenuated
third finger of the hand, which surpasses all the others in
length, although the whole hand is remarkably elongated.
It also differs from other lemurs in that all the toes of the
foot, with the exception of the first, have pointed claws,
and thus resemble the second toe of the ordinary kinds.
In size the aye-aye may be compared to a cat, and it has a
rounded and somewhat cat-like head, with a short face,
and large naked ears. The tail is long and bushy, and the
general colour of the fur dark brown.

The aye-aye represents the extreme development of the
lemur type, and it is evident that its peculiarities of
structure are correlated with equally well-marked traits of

AYE-AYE. 107

habit. Unfortunately, however, from the nocturnal habits
and rarity of the creature itself, as well as from the absence
of a sufficient number of competent observers in its native
haunts, we are by no means so well acquainted with the
habits of this strange creature as is desirable. It appears,
however, that the aye-ayes live either in pairs or alone in
the bamboo forests of Madagascar, and that they are in the
habit of constructing ball-like nests of leaves placed in the
forks of trees, to which they retire for their diurnal slumber.
The strong incisor teeth are certainly used for ripping up
the hard external cases of the sugar-canes, on which these
animals delight to feed; and it is said that they are like-
wise employed to tear away the bark and wood from the
trunks of trees, and thus expose the burrows of wood-eating
larve, which are then extracted by the aid of the thin
middle finger. If any of our readers who have friends
living in Madagascar can induce them to try and obtain
more particulars in regard to the aye-aye, they will be
conferring a real benefit on science.

108 ARMADILLOS AND AARD-VARKS.

CHAPTER XI.
ARMADILLOS AND AARD-VARKS.

Or the four animals represented in the figures accom-
panying the present chapter, three are sufficiently alike to
suggest to the ordinary observer their relationship to one
another, but the fourth is so utterly different, that it is
difficult to point out any important character it has in
common with the tbree others; nevertheless, naturalists
generally regard all these four strange creatures as
belonging to a single order of mammals, for which the
name of Edentata is adopted. The signification of the

term Edentata being toothless, the unsophisticated student
would naturally be led to suppose that all the animals so
named were utterly devoid of those useful but troublesome
appendages. This, however, is far from being the case, the
majority of the members of the group (among which are
those figured here) having a considerable number of teeth.

THE GROUP OF EDENTATES. 109

Still there is one feature in connection with the dentition
exhibited by the whole of these so-called edentates; and
this is, that teeth in the front of the jaws, corresponding
to the incisors of other mammals, are totally absent.
Instead, therefore, of being described as edentates, or
toothless mammals, these creatures ought rather to have
been named aprotodonts, or incisorless mammals. After
all, however, it is not much consequence what is the proper
meaning of a name, so long as we know the sense in
which it is used, and there is accordingly no real objection
to the employment of the term edentates, which bas
obtained the almost universal sanction of zoologists.

In addition to this total absence of front teeth, the
edentates are further characterized by the circumstance
that all their teeth (when they possess any) show no trace
of the hard layer of enamel which is so characteristic and
essential a constituent of those of other mammals; these
teeth at no period of life forming roots, but continually
growing from below. Moreover, in nearly all the eden-
tates there is never any set of milk-teeth developed,
although, unfortunately, this cannot be taken as a charac-
teristic of the order, sinc2 such teeth occur in one of the
armadillos, and also in the animal represented in our
fourth figure.

Premising that the edentates are quite distinct from the
marsupials and egg-laying mammals, we may say, then,
that the only features by which they can be collectively
characterized are the want of front teeth, and the absence
of enamel on those of the cheek series, while in certain
rare instances they may be utterly devoid of teeth. Such
characters, it must be confessed, are by po means of first
importance.

The mammals thus associated by these negative charac-
teristics, are now chiefly confined to the southern hemi-
sphere, and include the sloths, anteaters, and armadillos
of South America, the pangolins, or scaly anteaters of
south-eastern Asia and Africa, and the aard-varks of
Africa; the true anteaters and pangolins being those in
which teeth are wanting. In past times they were also
represented by the gigantic megathere, and a number of

110 ARMADILLOS AND AARD-VARKS.

other ailied extinct forms ranging throughout America,
which in some respects serve to connect the sloths with
the anteaters. This marked restriction of the existing
edentates in the southern hemisphere, and their especial
abundance in South America, at once stamps them as a
very lowly group of animals, there being a well-marked
tendency for the preservation of the humbler forms of life
in the southern contents and islands of the globe. There
is, indeed, a question whether the pangolins, and more
especially the aard-varks of the Old World, have any real
kinship with the more typical American edentates, but
apart from this possibility of the artificial nature of the
eroup as at present constituted there can be no doubt but
that all its members are what may be called degraded
types—that is to say, that instead of having advanced in
the struggle for existence they have lost some of the
attributes of the higher animals ; evidence of this degrada-
tion being afforded by the indications above mentioned of
their having been formerly provided with two sets of teeth.
In saying that the edentates are lowly and degraded
examples of the mammalian type we by no means intend,
however, to imply that they are not admirably adapted to
their own particular modes of life, or that they have not
developed special structures unknown among the higher
mammals. In truth, precisely the contrary is the case,
since these creatures have taken to modes of life unlike
those of the majority of the larger mammals, and have
more or less specially modified their structure in accordance
with such peculiar habits, so that they are thoroughly and
perfectly suited to their environment. And we may add
that it is doubtless due to these peculiarities of structure
and habits that they have been enabled to survive and
hold their own against the competition of the higher
forms.

Thus, in the first place, with the exception of a few
armadillos, the whole of the edentates are strictly noc-
turnal; and while the sloths spend the whole of their lives
among the branches of the dense forests of South America,
some of the others have taken to a burrowing subterranean
life. Moreover, the armadillos and the pangolins have

ANT-EATING. 111

acquired a special protection from their foes in the shape
of a bony or scaly armour, which is a perfectly unique
feature in the whole mammalian class. Another peculiarity
of the group is that no less than three distinct sections of
its members—namely, the anteaters of South America, the
pangolins of southern Asia and Africa, and the African
aard-varks—have taken to feed mainly or exclusively on
termites, or so-called white ants. This practice obviously
gives them an advantage in the struggle of existence, since
with the exception of the marsupial banded anteater and
the egg-laying spiny anteater of Australia (with which,
of course, they do not come into competition), no other
mammals are in the habit of subsisting exclusively on
those insects. And we may notice here that of the three
groups of termite-eating edentates, two—namely, the pan-
golins and the anteaters—are those which have entirely
lost their teeth ; while in the aard-varks those organs are
retained. As teeth are obviously of no sort of use to
animals subsisting on such a diet, we may regard the two
former groups as those most specially modified for their
particular mode of existence ; and it may thus be suggested
that they have taken to termite-eating for a longer period
than the aard-varks. A similar observation also applies
to the banded and spiny anteaters of the antipodes, the
former retaining a number of minute teeth, while in the
latter they have completely disappeared. Needless to say,
all termite-eating mammals, whether they be edentates,
marsupials, or egg-layers, have extremely long, narrow,
and extensile tongues with which to pick up their insect-
food; but the presence of such an organ does not, of
course, imply any mutual affinities between the possessors
thereof, and is merely an instance of the similarity of
organs arising from adaptation to a similar mode of
existence. The tongue of the aard-varks is, however, far
less elongated and extensile than that of the pangolins
aud true auteaters; and, therefore, tends to confirm our
suggestion as to the relative duration of time since the
ancestors of these creatures severally took to termite-
eating. Another instance of adaptation displayed by all
the edentates, except the arboreal sloths, is to be found in

112 ARMADILLOS AND AARD-VARKS.

the powerful and generally elongated claws or nails with
which their feet are armed, such claws being obviously
necessary for a fossorial subterranean existence. The
aard-varks, as will be seen from our fourth figure, have,
however, much shorter and blunter claws than any other
member of the group; and this leads me to hazard the
suggestion that, in addition to having taken at a com-
paratively late period to termite-eating, these animals
have not been accustomed to a subterranean life for so
long a time as their reputed kindred.

Having said thus much as to edentates in general, we
must turn to the special consideration of the creatures
whose names form the title of this chapter.

The armadillos, as their name (a Spanish one) implies,
are distinguished by the solid armour with which their
heads and backs are protected; and it is doubtless the
peculiar appearance presented by these animals to which
we owe the expression ‘“ hog-in-armour.” In all the
armadillo family the armour takes the form of a series of
thicker or thinner bony plates imbedded in the skin
covering the head and back, and overlain by horny scales ;
while the under parts of the body and jimbs are hairy,
and in many species a larger or smaller number of stiff
hairs protrude from between the joints of the armour. This
bony armour is a perfectly unique feature among existing
mammals; and since each plate is ornamented with a
more or less elaborate sculptured pattern, such armour
when cleaned by maceration forms a most beautiful object.
In the true armadillos, as the one represented in Fig. 34,
the shield of armour covering the head is quite distinct
from that of the body ; while the latter is divided into
three distinct portions, namely, a large solid shield covering
the fore-quarters, and separated by a larger or smaller
number of free movable bands occupying the middle of the
body from a nearly similar shield protecting the hinder
portion of the animal. In our first figured example the
number of the movable bands is only three, but they may
vary from six to nme (Fig. 36) up to as many as twelve or
thirteen in other species. In one extinct armadillo there
were, however, no solid shields, the whole body being

THE PICHICIAGO. 113

covered by a series of thirty-two movable bands. The
latter species evidently, therefore, leads on to the rare and
beautiful little creature represented in Fig. 85, which
rejoices in the name of pichiciago. In this tiny animal,
which is only about five inches in length, and has a pink-
coloured armour above, and long silky white hair below,
the armour of the head and body forms a continuous
shield of horny plates underlain by very thin plates of
bone, and is attached only to the middle line of the back,
so that the lateral portions form a kind of cloak loosely
overhanging the hairy sides of the body. The hinder end
of this cloak is abruptly truncated, and beneath it the
hind-quarters of the animal are protected by a solid bony
shield, through a notch in the centre of which protrudes

Fie. 35.—The Pichiciago.

the small cylindrical tail. The pichiciago is found on
sandy plains only in the western portions of the Argentine
pampas. It will be seen from our illustrations that this
creature also differs from the true armadillos in the

I

114 ARMADILLOS AND AARD-VARKS.

absence of the large external ears which form such a
characteristic feature in the physiognomy of the latter.

Reverting to the true armadillos, we find that the
majority of the species protect themselves from attack by
squatting on the ground, and tucking their hmbs within
the shelter of the edges of the armour of the body, while
the plated head is drawn as close as possible to the front
shield. On the other hand, the species represented in
Fig. 34:has the power of rolling itself up into a complete
ball, like the pill-millipedes of our own country, the wedge-
shaped head and tail fitting most perfectly side by side
into the deep notches of the front and hind shields.
Thus coiled up, the three-banded armadillo is safe from
most animals except man. Trusting in this immunity from
attack, this armadillo, together with two other species
inhabiting the Argentine, has become almost exclusively
diurnal in its habits. These diurnal habits, as Mr. W. H.
Hudson, in -his charming work, ‘The Naturalist in La
Plata,” suggests, may also have had the advantage of
avoiding any encounters with the larger animals of prey,
which are mostly nocturnal, and some of which may have
been able to break through the protecting armour, more
especially in the species which lack the power of rolling
themselves up. Whatever advantage may have formerly
accrued from these nocturnal habits before the appearance
of man on the scene, is, however, now completely lost in
cultivated districts, where these species stand a good
chance of being completely exterminated by the hand of
man.

On the other hand, the six-banded peludo, or hairy
armadillo (Fig. 36), of the Argentine, which differs from
its cousins in preferring an omnivorous diet to one of
insects, is a far wiser beast in its generation. This creature,
according to Mr. Hudson, adapts itself to the conditions
under which it exists, and thus stands a good chance of
surviving when its fully-armoured relatives perish. “Where
nocturnal carnivores are its enemies,” writes the observer
mentioned, “it is diurnal; but where man appears as a
chief persecutor, it becomes nocturnal. It is much hunted
for its flesh, dogs being trained for the purpose; yet it

115

ARMADILLOS.

Fig. 36.—Six-Banded Armadillo.

i |

116 ARMADILLOS AND AARD-VARKS.

actually becomes more abundant as population increases
in any district.” As I have witnessed, beneath any
decomposing carcase lying in the Argentine pampas the
burrow of a peludo is almost sure to be found ; and it is
not a little remarkable that the flesh of a creature which
has such unpleasant tastes in the matter of diet, should be
so eagerly sought after as an article of human consumption.
Before taking leave of the peludo we must not omit to
mention two other peculiar habits which are recorded of it
by Mr. Hudson, since these also mark it as a creature far
above the generality of its kind in point of intelligence.
The first of these peculiarities is the ingenious way the
creature catches mice, by approaching them with extreme
caution, raising itself on its hind-quarters, and then
suddenly proceeding to “sit down” on the unfortunate
rodents, which become entrapped under the projecting
edges of its armour. The sharp edges of the armour are
also brought into requisition when this armadillo attacks
a snake preparatory to devouring it; the snake being
pressed close to the ground beneath the edges of the bony
plates, and literally sawn to death by means of a back-
wards-and-forwards motion of the body of its assailant.
‘he largest of living armadillos is one which inhabits
the moist forests of Brazil and Surinam, and has a length
of about thirty-six inches, exclusive of the unusually long
tail, which is some twenty inches in length. These dimen-
sions were, however, vastly exceeded by some extinct
armadillo-like animals, of which the remains are found
in the caverns of Brazil. The most gigantic of these
creatures, which flourished during the Pleistocene epoch—
the period par eacellence of giant mammals—is estimated
to have been nearly equal in size to a rhinoceros, and has
been named the chlamydothere. The armour appears to
have been very like that of the true armadillos, but the
bony plates measured as much as five and six inches in
length, in place of little more than an inch. The teeth
differed, however, from the simple conical ones of the
modern armadillos, and more nearly resembled the verti-
cally fluted ones characteristic of the extinct glyptodonts.
Unfortunately, space does not admit of further reference

AARD-VARES. 117

to the gigantic creatures from the Pleistocene of. South
America, to which the latter name has been applied, all
of which are distinguished from the armadillos by the
armour of the body being welded into a single solid dome-
like shell.

Passing on to the animals whose name comes second in
the title of this chapter, we have first of all to mention
that the designations by which these creatures are com-
monly known exhibit that remarkable want of originality
in nomenclature which appears to be characteristic of
Europeans when they are brougut for the first time into
contact with hitherto unknown animals. Thus, whereas
the Dutch Boers of South Africa applied to the creatures
in question the title of ‘“aard-vark’’ (meaning “ earth-
pig”), the English colonists of the Cape commonly speak
of them as the ant-bear. Now, if there is any one parti-
cular animal which the aard-vark (as we must perforce
term the creature) is unlike, it is a bear ; while its resem-
blance to a pig is only of the most distant kind. Still,
however, as in the case of the order to which it belongs,
we must be content to designate the animal by the name
by which it is most commonly known.

In appearance, aard-varks, of which there are two species,
are decidedly ugly creatures, having thick ungainly bodies,
a long pointed snout, enormous erect ears, and a thick
cylindrical and tapering tail, nearly as long as the body.
The skin is eitber almost naked, or thinly covered with
bristle-like hairs. The fore-feet have but five toes, which
are armed with broad and strong nails, as are the five
toes of the hind limb. As we have already mentioned,
almost the only feature which the aard-vark bas in com-
mon with the armadillos is the absence of front teeth,
and its cheek teeth are quite unlike the simple ones of the
latter, as, indeed, they are dissimilar to those of any other
mammals. In the first place, they are preceded by a
functionless series of milk-teeth (a feature found else-
where among edentates only in one species of armadillo),
while in the second place the premolars are unlike the
molars. The latter are composed of «a number of closely
packed denticules, each furnished with a central pulp

118

ARMADILLOS AND AARD-VARKS,

(From Selater, Proc. Zool. Soc.)

7.—The Ethiopian Aard-Vark,

9
€

Fie.

AARD-VARKS. 119

cavity, and by their close approximation forming polygonal
prisms, so that a cross-section of one of these teeth
presents the appearance of a pavement. No dental struc-
ture among mammals is at all comparable to this, although
there is some approximation to it among certain fishes.

Of the two living species of aard-vark, one is confined
to South Africa, while the other (represented in our figure)
inhabits part of Egypt and other districts in the north-
western portion of the same continent. A third species
oceurs fossil in the Pliocene deposits of the Isle of Samos,
but with this exception the paleontological record is silent
as to the past history of these strange creatures, as to
whose origin and relationship to the other animals we are
at present utterly in the dark. Indeed, the aard-vark is
placed among the edentate mammals chiefly because
zoologists do not know where else to put it, and they take
that group as a kind of refuge for the destitute. Were it
not that the burdening of zoological science with new
names is from all points of view to be deprecated, there is,
indeed, much justification for regarding these animals as
the sole representatives of a distinct order; but, although
im some ways such a new departure would be convenient,
I do not know that in others it would be of any great
advantage. But in including them provisionally among
the edentates we have to recollect that their affinities with
other members of that group—not even excepting the
pangolins—must be extremely remote.

Aard-varks lead what would seem to us a very dull and
monotonous kind of Jife, passing the whole of the day
curled up in their deep burrows, which are generally ex-
cavated hard by the tall pyramidal hills made by the
termites, and only issuing forth at night to dig in the
mounds for their favourite insect-food. Nota great many
years ago it used to be said at the Cape that wherever a
clump of termite hills was to be seen there an aard-vark’s
burrow might be pretty confidently expected. Unfortu-
nately, however, this is no longer the case, and the aard-
vark of that district runs a good chance of being extermi-
nated at no very distant date.

This deplorable result is being brought about by the

120 ARMADILLOS AND AARD-VARKS.

incessant pursuit of these animals by the natives for the
sake of their hides and flesh, and also by their being dug
out by Europeans for so-called sport. Their flesh is said
to be excellent, and is compared to superior pork ; while
the value of each hide is about fifteen shillings. This
threatened extermination is a very short-sighted policy on
the part of the South African farmers, to whom the aard-
vark is a valuable ally, not only on account of the
enormous number of termites it consumes, but likewise
from the circumstance that while it is engaged in digging
for these insect-pests it covers with loose earth a quantity
of the seeds of grass and other pastoral herbage which
would otherwise perish during the hot season. Although
there is no likelihood at present of the Ethiopian aard-
vark sharing the threatened fate of its southern cousin,
yet the extermination of the latter would be a sad loss to
zoological science, and we therefore wish every success to
a movement which we hear has been set going by the
Cape Farmers’ Association for the protection of this most
strange and curious creature ere it be too late.

Addendum.—Quite recently some remains have been
discovered in the upper Eocene, or Oligocene strata of
France, which are considered to indicate the existence at
that period of small ancestral types of aard-varks.

THE OLDEST MAMMALS. 121

CHAPTER XII.
THE OLDEST MAMMALS.

Up to the year 1818 it was a generally received axiom of
geology that mammals were totally unknown before the
Tertiary period; and that period was consequently
designated the age of mammals—a name, by the way,
which is still perfectly 2 appropriate, if taken to imply that
these animals then, and then only, became the dominant
inhabitants of the world. In that year, however, the
illustrious Cuvier, during a visit to the museum at Oxford,
was shown two minute jaws, carrying a number of cusped
teeth, which had been obtained in the neighbouring
quarries of Stonesfield, from the rock known as the
Stonesfield slate, belonging to the lower part of the great
Jurassic, or Oolitic, system. After careful examination,
the French anatomist pronounced confidently that these
two tiny little jaws, neither of which exceeded an inch in
length, were those of mammals, and he further suggested
that they would prove to belong to a species of opossum.
Although this opmion was given in the year 1818, it does
not appear that it was published till the year 1825, when
the second edition of the fifth volume of the immortal
“Ossements Fosiles”’ saw the light. In publishing this
epoch-making notice of the occurrence of mammals in the
Secondary period, Cuvier, with the usual caution of
naturalists, was careful to add the proviso that everything
depended on whether the specimens he saw had really
been obtained from the Stonesfield slate. Unfortunately,
there does not appear to be any record stating by whom,
or at what date, these original specimens—now forming
some of the most valued treasures of the Oxford Museum
—were obtained from the Stonesfield slate; but that they
did come from that formation is perfectly certain. Indeed,
other specimens have been subsequently obtained from the
same beds, showing certain characteristic Stonesfield

122 THE OLDEST MAMMALS.

shells imbedded in the fragments of rock in which the
mammalian jaws are contained. Here we may mention
that the Stonesfield slate is the equivalent of the lower
portion of tbe great, or Bath, oolite—a deposit which is
separated from the underlying lias by the beds known as
the inferior
oolite. Conse-
quently, the
mammial-yield-
ing beds are
separated from
the rocks of the
Tertiary period,
not only by the
immense series
of Cretaceous deposits (chalk, gault, greensands, and
Wealden), but likewise by a large thickness of those
belonging to the Jurassic system, such as the Purbeck
and Portland oolites, the Kimeridge clay, the coral-rag,
and the Oxford clay.

Needless to say, no sooner was the existence of mammals
in the Stonesfield slate announced than it was received
with a howl of incredulity. First of all it was attempted
to show that the specimens themselves did not come from
Stonesfield ; and no sooner was this objection knocked on
the head than doubts were raised as to the Jurassic age of
the Stonestield slate itself. These, however, were equally
soon disposed of, and the only thing then remaining was
to dispute the mammalian nature of the fossils. This task
was undertaken by the French naturalist, De Blainville,
who attempted to show that the mammalian character of
the specimens was not proved by the double roots of their
molar teeth. In the course of the argument, great stress
was laid on the circumstance that two-rooted molars were
found in a gigantic animal from the Eocene of the United
States, then known as Bast/osawrus, and regarded as a
reptile. De Blainville was, however, here treading on very
dangerous ground, for it subsequently turned out that
Basilosaurus itself was really a mammal, which is now
generally placed among the whales, under the name of

Fra. 38.—One half of the lower Jaw of a
Stonesfield Mammal. Twice natural size. The
restoration of the front teeth is conjectural.

STONESFIELD SPECIES. 123

Zeuglodon. The correctness of Cuvier’s original determi-
nation was thus in the end triumphantly sustained, and
the existence of Jurassic mammals became henceforth an
established fact in geology, although the suggestion that
these fossils belonged to opossums was, of course,
unfounded.

Passing on to the consideration of the specimens them-
selves, we find that the great peculiarity of the jaws of
these Stonesfield mammals (for one of which De Bilainville
proposed the name of amphithere) is the excessive
number of their cheek-teeth, a feature now paralleled
only in the little banded anteater of Australia. This
multiplicity of teeth is well shown in the jaw represented
in Fig. 38, which is preserved in the museum at York,
and shows upwards of nine cheek-teeth still remaiming
whereas in practically all existing mammals with complex
teeth, except the banded anteater, the number does not
exceed seven. Other jaws were, however, subsequently
discovered in Stonesfield, in which the number of
cheek-teeth was considerably less; but one of these
later specimens (described as the phascolothere) revealed
the important fact that there were four pairs of front or
incisor teeth in the lower jaw. Now since it is only
among the pouched mammals, or marsupials, that more
than three pairs of incisor teeth are found, while the
banded anteater, with its numerous cheek-teeth, is a
member of the same group, it became a very natural
conclusion that the Stonesfield mammals were likewise
marsupials. Support was lent to this conclusion by the
circumstance that, with the exception of the egg-laying
mammals, or monotremes, the marsupials are the lowest
of all living mammals. And indirectly some further
support to this view is afforded by the fact that Australia
still retains other forms of animal life allied to those which
were living in Europe during the period of the Stonesfield
slate. For instance, it is in the Australian seas alone
that there still survives the solitary representative of the
beautiful genus of bivalve shells known as T’rigonia, which
were so especially abundant in the oolites; while it is also
there alone that swims the Port Jackson shurk, whose

124 THE OLDEST MAMMALS.

mouth is armed with a pavement of crushing teeth,
recalling those of many of its Jurassic forerunners.
Moreover, in the presence of numerous cycads among its
flora, Australia again recalls the Jurassic epoch of Europe ;
and it has accordingly been suggested that modern
Australia may be regarded as a kind of direct survival
from Jurassic times. Before, however, we can say any-
thing more as to the affinities of the Stonesfield mammals,
we must turn our attention to subsequent discoveries of
mammalian remains in other formations.

The first of these discoveries was made in the year 1847,
by Professor Plieninger, of Stuttgart, who obtained certain
minute teeth from a bone-bed near that city belonging to
the upper part of the Triassic period, which were declared
to be mammalian, and for the owner of which the name
Microlestes was proposed. Now, as the trias lies below the
lias, the existence of mammalian Jife was by this discovery
carried back at one bound very nearly to the commence-
ment of the Secondary period. Subsequently, mammalian
remains were obtained from the trias of Somerset, which
proved to belong to the same genus as those from Stuttgart,
while others of a different type were found in the
equivalent deposits of North America.

Fre. 39.—Lower Jaw of an American Jurassic Mammal ; twice
natural size. (After Marsh.)

A little later, the year 1854 was made memorable by the
first discovery of mammalian remains in the freshwater
Purbeck strata of Dorsetshire, belonging to the very top of
the Jurassic system; from which formation in subsequent

AMERICAN FORMS. 125

years a vast number of such remains were obtained, through
the energy of the Rev. P. B. Brodie and Mr. Beccles. All
these specimens were obtained from a single bed, and
many of them indicated forms more or less closely allied
to those from Stonesfield and Stuttgart. It was thus
shown, once for all, that mammatian life must have been
locally abundant throughout the Jurassic period. This
conclusion was subsequently amplified by the discovery in
the upper Jurassic rocks of North America of a whole

Fie. 40.— Lower Jaw of Triconodon ; twice natural size.

(After Marsh.)

host of small mammals very closely allied to those from
Dorsetshire, a large number of which have been described
by Prof. O. C. Marsh, some of whose figures are here
reproduced. Many of these small Jurassic mammals
(Figs. 39 and 40) were evidently carnivorous, and such
carnivorous forms exhibited two distinct types of dentition.
In one of them (Fig. 39) there was a numerous series of
cheek-teeth behind the tusk, or canine (a), each of which
carried three cusps arranged in a triangle; while in the
other type (Fig. 40) the cheek-teeth were fewer in number,
and had the three cusps on their crowns ranged in the same
line. From this peculiarity the animal to which the second
type of jaw belonged was appropriately named Triconodon.
The first type corresponds to the amphithere of the Stones-
field slate, while the second is more like the phascolothere
of the same formation.

In Fig. 40 it will be observed that there is a pecu-
liar groove (g) running along the inside of the jaw, and

126 THE OLDEST MAMMALS.

since a similar groove is found among existing mammals
only in the banded anteater and certain other carnivorous
marsupials, we have pretty conclusive evidence that Tricon-
odon and its allies were really marsupials. There can also
be but little doubt that the species of the amphitherian
type (I avoid mentioning the numerous genera of these
animals) are likewise members of the same order. It is,
however, quite possible that some of the Jurassic mammals
of Dorsetshire and North America may be more nearly
allied to that primitive group of mammals known as
Insectivores, among which are included the mole, the
shrew, and the hedgehog of Europe, as well as the more
generalized tenrec of Madagascar, and many other peculiar
creatures. All these insectivores are of a very low grade
of organization, and the result of modern researches is to
show that their connection with the marsupials is very
close indeed. Hence it is highly likely that some of the
Jurassic mammals may have been the actual connecting
links between the marsupials and the insectivores ; and it
is worthy of mention here that while marsupials at the
present day linger on only in Australia and America, some
of the most primitive types of insectivores are preserved
to us in Madagascar, which is another refuge for animals
of a low grade of organization.

There is yet
another type of
mammal found
in the English
and American
Jurassics, to
which the Micro-
lestes of the trias
also appears to
belong, which
has given rise to Fie. 41.—Lower Jaw of Plagiaulax ; natural

size and enlarged. (After Marsh.)

a vast amount
of discussion among the paleontologists. These re-
markable mammals are mostly of very minute size, and
were long known only by their lower jaws, of which
a specimen is represented in Fig. 41, from which it will

HERBIVOROUS TYPES. 127

be seen at a glance that the dentition is quite different
from that of either of the carnivorous types figured above.
The lower teeth comprise a single large incisor (a), behind
which were either three or four tall premolar teeth with
cutting edges, and marked on the sides with a number of
oblique grooves, from which the name Plagiaulax was
taken. When unworn, these grooves extended along the
whole outer surface of the teeth, but when the teeth had
been long in use (as in our figure) the groovings became
worn away from the sides. Behind these four premolars
are two smaller molar teeth, with the summits of their
crowns warked by a single longitudinal groove bounded
by prominent ridges. Now it was argued at first that
this very peculiar type of dentition indicated carnivorous
habits in the owners thereof; but it was subsequently
pointed out that the existing rat-kangaroos of Australia
(of which the front of the skull is shown in Fig. 42)
presented a some-
what similar type
of tooth-structure.
Thus, the last pre-
mnolar tooth (p.m.)
of the rat-kanga-
roo has a cutting-
crown marked
with a number of
parallel grooves ;
while each half
of the lower jaw
terminates in a
single large incisor not unlike that of the Jurassic Plagiau-
lax. Hence it was argued—and, in our opinion, argued
rightly—that as the living form is herbivorous, the same
must have been the case with the extinct one. When,
however, it was also urged that the rat-kangaroo and
Plagiaulax were closely allied animals, important differences
between the two were overlooked. For instance, as will
be apparent from the figures, while in the former there
was but one grooved tooth, in which the grooves are
vertical, in the latter there were usually three or four

Fie. 42.—Jaws and Teeth of Rat-Kangaroo.

128 THE OLDEST MAMMALS,

such teeth in which the grooves are oblique. Moreover,
whereas the recent form was provided with four molar
teeth (m 1—m 4), the fossil had but two such teeth ; while
the form of these teeth was quite unlike in the two.
Hence, when we add that there are other important differ-
ences between them (into the consideration of which it
would be difficult to enter here), it will be apparent that
the view of regarding Plagiaulax as a near ally of the rat-
kangaroo was the result of attaching too much importance
to resemblances, and overlooking differences. Indeed, such
resemblances as do exist between the two may be regarded
merely as a well-marked instance of the phenomenon of
parallelism, treated of in an earlier chapter.

Taking it, then, as proved that Plagiaulax is not a near
ally of the rat-kangaroo, we have to consider whether it
can be affiliated to any other group of existing mammals.
Before doing so, we have, however, to mention that there
are certain ghee Secondary mammals allied to Plagiaulaz,
in which the whole of the cheek-teeth are hke the true
molars of the latter. We have already stated that in
Plagiaulux the lower molars have a median longitudinal
groove, and it may be added that the ridges bordering
such grooves are surmounted by a number of small
tubercles. In the upper jaw, if we may judge by some
allied genera, the molars had three such tubercular ridges,
separated by two grooves. Similar molars occur in the
skull represented in Fig. 43, which is that of a mammal
discovered a few years ago in the Secondary rocks of
South Africa, and apie by Sir R. Owen Tritylodon ;
but it will be noticed that there is no trace of the
cutting and obliquely-grooved premolar teeth of Pla-
giaulax, the premolars being like the molars. Detached
molars of similar type have been found in the Trias of
Stuttgart, and others occur in the Stonesfield slate.
Moreover, in Dorsetshire and North America, there are
certain nearly allied mammals (Bolodon) in which the
upper molars have only two, in place of three, longitudinal
ridges of tubercles. These forms, if other. proofs were
wanting, clearly show, indeed, that the resemblance
between Plagiaulaa and the rat-kangaroo is not a genetic

CRETACEOUS TYPES. 129

one. When, however, the molar teeth of the type in
which there are but two longitudinal rows of tubercles are
compared with the transitory teeth of the Australian duck-
bill, a certain resemblance can be detected between the two,
which seems sufficient to indicate that in Plagiaulax and
Tritylodon we have to do in all probability with ancient
types of egg-laying mammals.

Till within the last few
years the Cretaceous period
formed a complete gap as
regards the history of
mammals; and seeing that
in Europe, with the excep-
tion of the Wealden, the
rocks of this system are
mainly of marine origin,
while some of them, like
the chalk, were laid down
in seas of considerable
depth, this absence of
mammalian remains is not
to be wondered at. In the
United States the condition
of things is, however, very
different. There the upper-
most Cretaceous rocks are Pie, 40 Vader pat ok the
of fresh-water origin, and gkull of a South African Secondary
constitute a series known Mammal. Two-thirds natural size.
as the Laramie, which is in
intimate connection with the lower part of the Tertiary,
and has yielded the extraordinary horned dinosaurs. From
these Laramie Cretaceous rocks Prof. Marsh has succeeded
in obtaining a quantity of teeth of mammals, although
these are, unfortunately, mostly found detached. These
teeth indicate mammals closely allied to Plagiaulaz of the
Jurassic, and also others of a carnivorous type related to
Amphitherium, or some of the many-molared carnivorous
forms from the Dorsetshire Purbeck. Mammals of the
Triconodont type—that is, those with the three cusps of
the molars in a straight line—seem, however, by this time

K

130 THE OLDEST MAMMALS.

to have totally disappeared. At a still later date a single
tooth of the Plagiaulaz type, as well as one allied to
Bolodon, have been described from the English Wealden,
indicating that at that epoch the Purbeck mammals still
survived in Europe, and leading to the hope that future
researches will yield us further evidence of the European
mammalian fauna of the Wealden.

The present state of our knowledge, therefore, shows
that from nearly the lowest beds of the Secondary period
till the close of that vast epoch, there existed a numerous
fauna of small mammals distributed over a large portion
of the globe, and displaying a remarkable persistence of
nearly similar type. It is further evident that such of
these mammals as exhibit a carnivorous type of dentition
appear to be allied to the more primitive of the existing
marsupials, although some of them may be more nearly
related to the almost equally low insectivores. On the
other hand, those which exhibit what appears to be an
herbivorous modification of dental structure, if they are
related to any living forms, appear to have an affinity with
the modern egg-laying mammals of Australia. Now the
latter, together with the marsupials and insectivores, being
the lowest representatives of mammalian life at present
existing, are precisely such mammals as we should natu-
rally have expected to have been foreshadowed by more
or less nearly allied forms in the Secondary rocks; and,
therefore, in this respect, theoretical paleontology is, so
far as our present knowledge goes, precisely in accord
with actual facts.

That the few Triassic mammals at present known were
the earliest representatives of the class cannot, however,
be admitted for a moment, and we must accordingly look
either to the lower Triassic rocks, or to those of the
underlying Permian (forming the top of the Paleozoic
series), for the discovery of such primitive types. Should
such ever be discovered, it is to be confidently expected
that they will exhibit such a combination of characters
common to mammals, and certain extinct reptiles and
amphibians, that it will be very hard to say under what
class they will have to be ranked.

TERTIARY MAMMALS. 131

Seeing that throughout the whole of the Secondary
period, with the possible exception of a few lowly insecti-
vores, there is no evidence of the existence of any mammals
belonging to the higher placental type (under which are
included all living representatives of the class save the
marsupial and egg-laying groups), the reader will naturally
inquire when such higher forms first made their appear-
ance. We answer, with the first dawn of the Tertiary
period ; for in the very lowest Eocene strata both of France
and the United States there are found, side by side with
small mammals allied to Plagiawlar and the marsupials
of the Jurassic and Cretaceous, others, which, though still
of small size, were evidently placentals. And it is very
remarkable that this first definite appearance of the higher
forms of mammalian life should, so far as we know, have
been contemporaneous with the disappearance of so many
gigantic types of extinct reptiles, such as the dinosaurs,
the fish-lizards, and the plesiosaurs, which seem to have
reached the end of their term of existence at or about the
close of the Secondary period.

Most of these early Tertiary mammals had molar teeth
carrying three cusps arranged in a triangle, like their
marsupial forerunners of the Secondary epoch, from
which, indeed, they were probably derived; and at this
comparatively early epoch the orders of mammals were
but very imperfectly differentiated from one another, it
being frequently difficult to decide which were carnivores
and which were ungulates. <A few stages later differentia-
tion of ordinal types, accompanied by a great increase in
the bodily size of their representatives, had, however, taken
place; and by the close of the Hocene period, as exemplified
by the higher deposits of the Paris basin, most of the
present orders of mammals were well defined. Thence,
through the succeeding Miocene and Pliocene epochs,
there went on a continual evolution of mammalian lite,
resulting in the production of giant forms like the elephant
and the rhinoceros, and also characterized by the develop-
ment of specially modified types like the horse and the ox,
which differ so widely from their five-toed ancestors.
During the same epochs antlers were developed in the

K2

132 THE OLDEST MAMMALS.

deer and horns in the rhinoceroses and oxen, while pigs
and hippopotami gradually acquired the enormous tusks
with which their existing representatives are armed.

Seeing, then, that it was not till the advent of the
Tertiary period that: mammals assumed the position of the
dominant forms of life, Cuvier’s memorable discovery in
the second decade of this century that the class dated from
the middle of the Secondary period has in no essential
respect served to dispossess the first-named epoch from its
claim to the title of the Acz or Mammats.

CROCUDILES AND ALLIGATORS. 133

CHAPTER XIII.
CROCODILES AND ALLIGATORS.

In spite of the circumstance that numerous examples of
those ungainly reptiles known as crocodiles and alligators
are exhibited in the reptile house of the Zoological
Society’s Gardens in a living condition, while their stuffed
skins and articulated skeletons are displayed in the galleries
of the Natural History Museum at South Kensington,
there appears to be a hopeless confusion in the public
mind between these two very different creatures. And,
with the usual perversity of those not acquainted with the
ordinary facts of natural history, residents in India
increase this confusion by almost invariably speaking of
the crocodiles of that country as alligators, whereas an
alligator is not to be found from one end of India to
another. A remarkable instance of this confusion occurs
in Sir 8. Baker’s “ Wild Beasts and their Ways,” where,
under the heading of crocodile, it is stated that, “as
lizards are found distributed in great varieties throughout
the world, in like manner we find the largest of all lizards,
the crocodile, under various names in nearly every river
of the tropics. In America this reptile is generally known
as an alligator, and some persons pretend to define the
peculiarity which distinguishes that variety from the
crocodile, but I regard the distinction in the same light
as that between the leopard and the panther, the difference
existing merely in a name.”

Now, iv the first place, although it may be justifiable in
popular language to use the term “lizard” as applicable to
all four-footed reptiles except tortoises and turtles, yet,
scientifically speaking, a crocodile has not the slightest
right to be so termed. Indeed, it would be far preferable
to speak of a snake as a kind of lizard, since it is really
only a special modification of the lizard stock; and from
a strictly scientific point of view it would imply much less

134 CROCODILES AND ALLIGATORS.

confusion of ideas to call a cow a kind of pig than to term
a crocodile a lizard, since whereas a cow and a pig are
mammals belonging to the same section of a single order,
lizards and crocodiles represent two totally distinct orders
of reptiles. With regard to the statement that the dif-
ference between a crocodile and an alligator is merely one
of name, the reader who follows us through this chapter
will probably hold a different opinion by the time he
reaches the end.

So far as external appearance goes, most people are
aware that crocodiles and alligators are large, long-tailed,
low-bodied reptiles, with flat and frequently broad heads,
and their bodies protected by a coat of scales, which vary
greatly in size in its different regions. They probably also
know that it is the impressions of these scales, or of the
bony scutes by which those of the back are underlain, that
form the well-known markings on the crocodile-skin now
so commonly used for bags and other leather articles. In
their short and clawed limbs there are five toes in the
front pair, and four in the hinder, those of the latter being
connected together for a part of their length by a web.
As regards their habits, crocodiles and alligators are typical
amphibious creatures, being perfectly at home in the
water, but also capable of active progress on land, on which
their eggs are laid and the young hatched. The position
of their external nostrils at the very tip of the snout
enables them to come to the surface for the purpose of
breathing without showing more than their muzzle, or, at
most, this ard their somewhat prominent eyes. These
external characters will enable us to recognize an alligator
or crocodile when we see it, and yet do not show us how
these creatures differ so essentially from true lizards as to
render it incorrect to speak of them merely as a particular
group of lizards. To render this essential distinction
apparent we must enter into certain details of their
anatomical structure, more especially as regards the skull.
Now, in the first place, a crocodile or alligator may be
at once distinguished from every true lizard by the
circumstance that its large and pointed teeth are inserted
in the jaws in distinct and separate sockets, from which

STRUCTURE OF SKULL. 135

they will readily fall out in a dried skull; whereas
those of lizards, which vary greatly in form, are in-
variably united by solid bone with the edges or
sides of the jaws, without any separate socket. More-
over, in a crocodile’s skull, there is a bar of bone running
backwards from the lower border of the eye-socket, or
orbit (Fig. 44, O), to join the condyle with which the
lower jaw articulates. ‘his bar is seen in Fig. 44, below,
aud to the
left of the
letter O,
and also
occupying
the same
relative
Fra, 44.--Side view of the Skuliof a Crocodile; Position in

O, eye-socket or orbit. Fig. 46. It

willfurther

be apparent from the latter figure that in a crocodile’s skull
there are two parallel bars running backwards from behind
the orbit, of which the upper one is the stouter. Now
in a lizard’s skull, only the uppermost of these two bars
is present ; and we thus have a second important distinc-
tion between a crocodile and alizard. A still more impor-
tant difference occurs, however, in the under part of the
skull. Thus, whereas in a lizard the external nostrils
open directly through the palate into the front part of
the mouth, in a crocodile the bones of the palate develop
a kind of flooring beneath its roof, and thus form a closed
passage by which the internal or posterior nostrils are
brought to the very hinder extremity of the skull; this
remarkable peculiarity being well exhibited in Fig. 45, A,
where WN indicates the internal nostrils. The small round
aperture seen in the front of the palate in both A and B
is closed during life with membrane, and thus prevents
any communication between the external nostrils and the
front of the mouth. The object of this peculiar arrange-
ment is to enable the animal to breathe when its mouth
is open under water, and the nostrils are alone in the air ;
this being effected by the closing of the back of the mouth,

136 CROCODILES AND ALLIGATORS.

in front of the internal nostrils, by means of a fold of
skin, thus leaving a free communication between the
nostrils and the wind-pipe. The advantage of this
arrangement to animals which, like crocodiles and
alligators, kill their prey by holding them under water, is
self-apparent.

Fic. 45.—Lower view (A) of Skull without the lower
jaw, and (B) upper view of Skull with lower jaw of
a Crocodile. O, orbit; 7, temporal pit; /, palatal
vacuity ; VV, internal nostrils.

If to these differences between the- skulls and teeth of
crocodiles and lizards, we add that, whereas in the latter
the ribs articulate to the jomts of the back-bone or
vertebre by means of little knobs on the sides of the
vertebre themselves, in crocodiles they join the summits
of long horizontal processes of bone projecting from the
upper part of these vertebrz, we think we shall have said
enough to convince our readers that it is altogether in-
correct to speak of crocodiles and alligators as lizards.
Crocodiles are, indeed, first cousins of those extinct

THEIR DIFFERENCES. 137

reptiles known as dinosaurs, and ought, therefore, to
be regarded with respect as being the sole existing,
although collateral, representatives of that great group of
reptiles which dominated the earth at a time when
mammals were only just beginning their career,

Having said thus much as to the distinctness of croco-
diles from lizards, we may proceed to consider how the
former differ from alligators, and to make some mention
of a few of the various species of each. Now if we examine
the skulls of the different kinds of crocodiles we
shall find that the number of teeth in the upper jaw
varies from seventeen to nineteen, while in the lower
jaw there are invariably fifteen; and we shall likewise
find that the teeth of the two jaws interlock with
one another when the mouth is closed. Moreover, when
the jaws are in apposition it will be observed that
the first tooth on each side of the lower jaw is received
into a pit in the palate of the skull, while the fourth
lower tooth, which (like the first) is larger than the
others, bites into a notch in the side of the skull (as shown
in Fig. 44), and is thus more or less distinctly visible
externally in the living animal. Crocodiles are now found
in the rivers of Africa, India, Burma, Australia, and
America,as well as in many of the larger islands in warm
regions. They vary greatly in regard to the relative
length of the skull, the longest-snouted species occurring
in South America and West Africa, while those of India
have the shortest and broadest skulls (Fig. 45). Ov the
other hand, if we examine the skull of an alligator, we
shall find that the upper teeth bite on the outer side
of the lower ones without any sort of interlocking, and
both the first and the fourth lower teeth are received into
pits in the skull, so that when the mouth is closed both of
them are totally invisible from the outer side. Moreover,
in no alligator does the number of lower teeth ever fall
short of seventeen. Again, in all alligators the skull is
even broader and shorter than in the Indian crocodiles.
Till within the last few years it was believed (in spite of
the persistent assertion of sportsmen, that the Indian
“magars,” as they are called by the natives, are alligators)

138 CROCODILES AND ALLIGATORS.

that alligators were confined to the New World, but
recently it has been found that one species exists in
China. This is, indeed, a very curious instance of what
is known as discontinuous distribution, and one which
only finds a complete parallel in the case of the tapirs, of
which there is one species inhabiting the Malay peninsula
and adjacent islands, while all the others are restricted to
South America. There are several species of alligators,
which are divided into two groups, according as to whether
an armour of bony plates, or scutes, is or is not developed
on the under surface of the body. In the true alligators,
which agree with all living crocodilians in having a dorsal
armour of these bony scutes, the upper teeth vary from
seventeen to twenty in number, and those of the lower
from eighteen to twenty, while there is no bony armour
on the under surface of the body. The two well-known
species are the Mississippi and the Chinese alligator, in
addition to which there 1s a third American form of
which the exact habitat is unknown. The second group
of alligators, or caimans, as they are called in Brazil, is
confined to South America, where it is represented by five
species. These are characterized by having from eighteen
to twenty upper, and from seventeen to twenty-two lower
teeth on each side, and also by the lower surface of the
body being protected by a shield of bony scutes, which
overlap one another like the tiles on a roof, and each of
which is composed of two separate pieces united together
by what is known as a sutural union.

The above, then, are the chief differences which distin-
guish alligators and caimans on the one hand from
crocodiles on the other, and they are such as surely do not
justify the statement that naturalists merely pretend to
distinguish between thetwo. Alligators and crocodiles do
not, however, exhaust the list of living crocodilians, since
we have two peculiar species differing from all the others
by the great length of their snouts, and respectively
inhabiting the Ganges and the rivers of Borneo—the
former being known as the garial, and the latter as
Schlegel’s garial. In both of these reptiles the numerous
teeth are long and slender, and differ from one another

EXTINCT FORMS. 139

but little in size in different parts of the jaw, while
neither of them have an armour on the lower surface of
the body. They differ from crocodiles and alligators in
feeding chiefly on fish.

In regard to their geological distribution, crocodilians
more or less closely allied to the existing garials, crocodiles,
and alligators, are found throughout the rocks of the
Tertiary period as far down as the London clay. Some of
these extinct species were, however, of gigantic dimensions;
one from the Siwalik Hills of India, which was allied to
the garial, attaining a length of between fifty and sixty
feet, and thus presenting a great contrast to living croco-
diles, which rarely exceed a length of some twenty-two or
twenty-three feet. Another species found in the Tertiary
clays of Hampshire presents characters intermediate
between crocodiles and alligators, the fourth lower tooth
being usually received into a pit in the skull, but the
under surface of the body having a complete bony armour
like that of the caimans. This genus (Diplocynodon)
differs from both crocodiles and alligators in that both
the third and fourth lower teeth are larger than the
adjacent ones, so that the animal had two powerful tusks
in the sides of the lower jaw.

A few crocodilians, more or less closely allied to existing
types, also occur in the Cretaceous rocks, but when we
reach the Wealden and Jurassic strata nearly all the forms
differ very marked]y from modern ones, and show a lower
stage of development. Before, however, we are in a
position to understand how these early crocodilians differ
from their living cousins, we must enter a little more fully
into the anatomy of the latter. Turning once more to
Fig. 45, we see that the passage leading to the internal
nostrils is formed by four pairs of bones, on the fourth of
which the letter Nis placed. Again, in all living croco-
dilians the vertebre articulate with one another by a ball-
and-socket joint, of which the cup is situated at the front
of each vertebra; this mode of articulation being the
best adapted to give free motion of one vertebra upon the
other. The third point we have to notice relates to the
bony armour of living crocodilians, in all of which the

140 CROCODILES AND ALLIGATORS.

pitted scutes forming the shield on the back are ridged,
and arranged in from four to eight longitudinal rows.
Moreover, in the caimans and the extinct Diplocynodon, the
shield on the under surface of the body forms a single
mass, made up of more than eight longitudinal rows of
scutes, each of which, as already mentioned, consists of
two separate pieces united together by suture.

If we now contrast these features with those obtaining in
the Jurassic crocodilians, we shall find very considerable
differences. Thus in the skull of those reptiles the fourth
pair of bones on the palate did not meet in the middle line
below the passage to the nostrils, so that the internal nos-
trils were placed immediately behind, or sometimes partly
between, the bones lying between PP in Fig. 45, and were
thus much forwarder than in modern crocodilians. Then,
again, the vertebree were slightly cupped at both ends, thus
admitting of much less motion between one another. The
armour on the back of the body is of a similar type, consist-
ing only of two longitudinal rows of scutes, which lack the
longitudinal ridges so characteristic of those of the existing
forms. On the other hand, the armour on the under surface
was nearly always present and more developed, frequently
consisting of two distinct portions, in the foremost of which
the scutes (which consisted of a single piece) overlapped
like slates, while in the hinder part they were joied by
their edges to form a solid pavement of bone.

Like their modern cousins, the Secondary crocodilians
included both long-snouted (Fig. 46) and short-snouted

Fig. 46.—Side view of the Skull of an Extinct Crocodilian of the
Lias; one-fourth natural size. Letters as in Fig. 45.

types, the former being the more common and especially
abundant in the las, where their remains occur in com-
pany with those of fish-lizards and plesiosaurs. In many

THEIR EVOLUTION. 141

of these forms the pit (7') in the temporal region of the
skull was larger than the socket of the eye, whereas in
recent crocodiles it is much smaller (Fig. 45), and in the
alligators may even disappear. A large number of these
Jurassic forms were of marine habits, and a few of them
attained enormous dimensions, the length of the skull of
one species falling not much short of five feet. A few
species are further peculiar in having altogether discarded
their bony armour cn both surfaces of the body.

Looking at crocodilians asa whole, it is perfectly evident
that they have advanced in complexity of organization
with the progress of time, the backwardly-placed internal
nostrils and ball-and-socket vertebrz of the modern types
being clearly an advance on the Jurassic forms. As,
however, is the case in many similar instances, the gradual
backward shifting of the internal nostrils presents a
problem difficult to understand, as it is hard to conceive
what advantage the species in which these nostrils were
situated in the middle of the palate had gained over
reptiles in which they were placed near the muzzle, the
completely backward position being apparently essential
in order that the mouth might be kept open under water.

With regard to the general disappearance of the inferior
body-armour and the invariably increased development of
that on the back of the recent forms, it may be suggested
that, as most of the Jurassic crocodilians were of marme
habits, and probably swam far out to sea, it would have
been highly advantageous for them to have the lower sur-
face of the body protected from attacks from below, by
sharks and other creatures. On the other hand, since
modern crocodiles and alligators spend a considerable
portion of their time on the banks of rivers, and when in
the water are in the habit of reposing or crawling on the
bottom, it is obvious that the back is the portion which
requires especial protection. An explanation of the exist-
ence of an armour on the lower surface of the body in
the caimans is less easy to give, although it may be merely
an instance of the retention of an ancestral character.

We may conclude this account by referring to some
interesting observations on the eggs and embryos of the

142 CROCODILES AND ALLIGATORS.

crocodile of the Nile. It appears that in Madagascar
the egg-laying lasts from the end of August to the end of
September, the number of eggs in a nest varying from
twenty to thirty. The nest is dug about two feet deep in
the dry white sand ; the bases of its wall are gouged out,
and into the lateral excavations thus formed the eggs roll
from the slightly raised centre of the floor of the nest.
Externally the nest is not discernible, but the parent
sleeps upon it. The eggs differ greatly in form; the shell
is white, thick, firm, and either rough or smooth, the
double shell-membrane being so strong that the egg keeps
its form after the shell has been removed. When newly
laid, the eggs are very sensitive, and are readily killed by
damp or by heat, but the older eggs are hardy. When
the young embryos are about to be hatched, they utter
distinct notes, which the mother hears, even through two
feet of sand, and proceeds to dig open the nest. Before
hatching the embryo turns, and in so doing partially tears
the foetal membranes. With the tip of its snout turned
to one end of the egg, the young animal bores through
the shell with a double-pointed tooth comparable to that
which young birds possess. This tooth appears very
early—by the time the embryo is six weeks or two months
old—and may still be seen a fortnight after hatching.
Through the small perforation made by this tooth the
fluid flows out, softening the adjacent parts, so that the
aperture is widened into a cleft. The process of creeping
out may take about two hours. The young animal seems
large in comparison with the egg; one measuring 28 cm.
in length came out of an egg 8 cm. long and 5 cm. broad.
The young crocodiles are wild little animals, and are led
to the water by the mother. They utter sounds, especially
when hungry, but the pitch of their call is not so high as
it was when they were within the egg.

THE OLDEST FISHES AND THEIR FINs. 143

CHAPTER XIV.
THE OLDEST FISHES AND THEIR FINS.

Ir is a well-known fact that while the fishes of the more
ancient periods of the earth’s history were frequently
characterized by having their bodies protected by a coat of
armour, this armour has been lost by most of their modern
descendants. Nevertheless, a few of these mail-clad fishes,
like the gar-pike of the rivers of North America, and the

SS
Ser as

Fie. 47.—The Bichir.

rivers of the West Coast, still linger on, as if for the
purpose of showing us what their ancestors were like.

In addition, however, to their. armour, and its gradual
loss with the advance of time, there are many other points
of view from which these ancient fishes are of more than
ordinary interest, and we accordingly propose in this
chapter to consider the curious modifications which have
taken place in the structure of their fins as we ascend in
the geological scale. We shall, moreover, be led to notice
briefly one of the most remarkable types of fossil fish
teeth found in the older Secondary rocks, since we can
thereby prove that one of our living fishes is the oldest
kind of vertebrate now inhabiting the earth.

Before going further, we must mention that existing
fishes have been divided into several main groups, dis-
tinguished from one another bv structural peculiarities.
One such group includes the sharks and rays, characterized
by their cell-like gills and scaleless bodies. Then we have
the smaller group of lung-fishes, now represented by the

144 THE OLDEST FISHES AND THEIR FINS.

lung-fish of Queensland, and the mud-fishes of the rivers
of Africa and South America, all of which can breathe
either by gills or by lungs. Another group is formed by
the so-called ganoid fishes (Fig. 48), :

many of which have the bony armour
already mentioned; while the great
majority of the fishes of the present
day, although nearly related to these
ancient ganoids, have been generally
separated as a distinct group, under
the title of bony fishes. That name
they take from the circumstance that
their skeletons are fully ossified, and
do not partake of the cartilaginous
nature of those of a shark or a
ganoid.

‘ Now if we look at the paired fins
(or those which correspond with our
own limbs) of any ordinary bony fish,
such as the perch (Fig. 49), we shall
see that they are formed of a number
of bony rays, starting from a single
point of origin, and thence spreading
out ina fan-lke manner. We shall
also not fail to observe that the tail of
such a fish has a very similar kind of
structure, likewise consisting of bony
rays, symmetrically arranged, and
starting from a curved line where the
scales suddenly stop. We may also see
from the figure of the skeleton of
sucha fish that the backbone likewise
stops suddenly where the tail begins,
and that the rays of the latter start
from the expanded end of the back-
bone itself.

The same general type of structure
obtains in the paired fins of some of
the later ganoids, such as the living
sturgeons, as wel! as certain extinct forms, and it is also

wee
=
an

Fia, 48.—An Extinct Ganoid Fish.

SS

SSS

ox

STRUCTURE OF FINS. 145

universally present in all the living sharks and rays. If,

,

however, we were to go to the Natural History Museum
and examine the lung-fish of the rivers of Queensland,
or the gar-pike (Lepidosteus) of those of North America, or

Fic. 49.—Skeleton of the Perch. a—c, jaws; d, eye; ef, portions
of skull; gg’, backbone; 4, pectoral fin; i, pelvic fin; & J, first
and second back-fins; m, anal fin; » »’, tail; 2 and i are the
paired fins.

the bichir (Polypterus) of the wpper Nile and the rivers
of western equatorial Africa, we should find a totally
different structure obtaining in the paired fins. In all these
three fishes (of which, be it carefully noted, the first is a
representative of the lung-fishes, while the second and
third are ganoids) the first pair, or pectoral fins, as is well
shown in the bichir, represented in Fig. 47, are seen to
have a long central lobe running for some distance up the
middle of the fin, and completely covered with scales,
while the rays of these fins form a kind of fringe, radiating
on all sides from the central lobe, the skeleton of a fin of
this type being shown in Fig. 50.

From this it will be seen that such a fin consists inter-
nally of a long cartilaginous axis, composed of a number
of joimts (1—9), and that from one or both sides of such
joints there are given off obliquely other smaller jomted
rods terminating in the fine rays forming the free edges

L

146 THE OLDEST FISHES AND THEIR FINS.

of the fins. How totally different in construction is this
kind of fin from that of the perch will be manifest from
our description and a com-
parison of Fig. 49 with Fig.
50. Fishes with paired fins
like those of the perch may
be well termed fan-finned
fishes ; while those with fins
of the type represented in
Figs. 47 and 48 may be known
as the fringe-finned fishes.

At the present day the only
fringe-finned fishes are the
Australian lung-fish and the
African and American mud-
fishes (which, as we have said,
are the sole living repre-
sentatives of the group of
lung-fishes), together with the
Fie. 50.—Skeleton of Pectoral bichir and an allied SPECIES)

Fin of an Extinct Shark, @Md the gar-pike, which, as
(After Fritsch.) we have seen, belong to
the ganoids. All the oldest
ganoids, such as those found in the old red sandstone of
Scotland (Fig. 48), are, however, likewise of the fringe-
finned type; and since a gradual passage from these
primeval ganoids can be traced through later ganoids
found in the upper Paleozoic and Secondary rocks to the
bony fishes so characteristic of our present seas and rivers,
there can be no manner of doubt but that the fringe-
finned type is the most ancient one, and has gradually
become modified into the modern fan-finned form.

The evidence that the fringe-finned type is the oldest
does not, however, stop here; for, curiously enough, not
only had the early ganoids and lung-fishes this kind of
fin, but the same type likewise obtained in the primeval
sharks. The fin-skeleton represented in Fig. 50 belongs
indeed to a member of the same group of sharks as does
the species of which the entire skeleton is shown in
Fig. 51, where the rod-like axis in both pairs of fins is

TYPES OF FINS. 147

distinctly seen. Now we
have already mentioned that
modern sharks and rays have
fan-like fins ; and it is,
therefore, clear that both in
the sharks and in the com-
pound group represented by
the ganoid and the bony
fishes there has been an in-
dependent transition from the
fringe-finned tothe fan-finned
type. On the other hand,
in the Inung-fishes, which,
as we shall see shortly, are a
very ancient race, the fringe-
finned structure has been
preserved without alteration
throughout countless ages.
We are still unacquainted
with the habits of some of the
living fringe-finned fishes, but
at least the lung-fishes are
species living partially buried
in the mud, and are evidently
not adapted for swimming
rapidly. On the other hand,
the fan-finned modern fishes,
whether they be sharks or
whether they be bony fishes,
are generally adapted for
rapid motion in the water.
Any person who has watched
a bow] of gold-fish will not
have failed to notice the
incessant and rapid motion
of their film-like fins, aud it
is quite evident that this
rapid motion could only be
produced by fins of the fan-
like structure. The fringe-fins
L2

DELS

LEELA.

Fia. 51.—Skeleton of an Extinct Shark, greatly reduced. (After Fritsch.)

148 THE OLDEST FISHES AND THEIR FINS.

are, indeed, more like clumsy paddles, capable only of
comparatively slow and steady motions ; such movements
being sufficient for fishes protected either by the bony
armour of the ganoids, or by the spines with which the
early sharks (Fig. 51) were armed. The fan-like fin is,
therefore, obviously the most specialized type of structure,
and as the ganoids im their advance towards the bony
fishes gradually acquired this fan-like fin, and with it, we
may presume, increased speed, it was essential that their
enemies the sharks should follow suit in order to be able to
catch their prey. This would appear to be a sufficient
reason for the attainment of the fan-like structure of fin in
both these groups of fishes. It is, however, very remark-
able that this structure of the fins having been indepen-
dently developed in the two groups should have become so
alike as it is. On the other hand, the lung-fishes,
together with the gar-pike and the bichir, never having
had occasion to abandon the mud-loving and sluggish
habits of their Paleozoic ancestors, have fortunately
preserved for us intact the old fringe-finned type of
swimming organs.

It is not, however, in regard to these paired fins alone
that fishes show a modification from a long, jointed, axial
structure to one which stops suddenly in an expanded
termination, from which arises a fan-shaped arrangement
of rays, the same kind of modification, although far less
generally, having also taken place among fishes in the
structure of their tails.

Thus, in all the primeval fishes the backbone (as shown
in Fig. 51) is continued right to the very end of the tail,
where it terminates in a point. On either side of the
backbone are fringes of fin-rays, so that (as shown in
Fig 48) in scaled fishes the scaly part of the tail is con-
tinued nearly to its extremity. his type of tail is there-
fore exactly similar in structure to the fringe-finned type
of fin, and may be similarly known as the fringe-tailed
type. In some fringe-tailed fishes the fringes on either
side of the tail (as in Fig. 47) are of nearly equal depth.
In other instances, however, the fringe of rays on the
lower side is somewhat deeper than that on the upper;

DEVELOPMENT OF TAIL. 149

and a further development of this inequality results in the
partially-forked tail of the sharks, where the end of the
backbone is bent upwards into the upper and longer
half of the tail, the lower lobe of which is formed solely
of rays. Sharks and lung-fishes have, indeed, never
advanced beyond one or other of these two modifications of
the fringed-tailed type. On the other hand, the com-
pound group, including the ganoids and the bony fishes,
was by no means satisfied with the primitive arrangement
of matters. Starting from a fish of the fringe-tailed type
like the one a
represented in
Fig. 48, we
may trace a
gradual short-
ening of the
central part of
the tail - fin,
accompanied
by an increas-
ing develop-
ment of the
rays on its,
lower side, un- %
til we finally
reach the com- oa :
pletely-forked Fie. 52.—Right Upper Tooth of an Extinct
tail of the Lung-Fish (Ceratodus). C. point of contact
pere h (Fig. with opposite tooth. (After Teller.)

49), in which, as we have seen, the backbone stops
short of the fin-rays, and ends in an expanded ex-
tremity from which these rays are given off in a fan-like
manner. The bony fishes have, therefore, not only
succeeded in developing the fringed-fins of their ancestral
ganoids into those of a fan-like type, but have likewise
effected a precisely similar modification in the structure
of their tails. That the fan-like tail of the perch is an
improvement as a steering organ upon the fringed tail of
the early ganoids there can be no doubt; and it is such an
organ which alone could regulate the movements of the

150 THE OLDEST FISHES AND THEIR FINS.

bony fishes in the delicate manner observable in a bowl of
gold-fish. To the sharks, however, whose movements
largely partake of vigorous rushes, it is probable that the
forked modification of the fringe-tailed type is more
advantageous than would have been a tail of the fan
type.

Tabor leaving the subject of the tails of fishes, we
cannot forbear to mention that the alteration from the
fringed type, with its long central axis formed by the back-
bone, from each joint of which springs a pair of rays, to
the fan-like type, with all the rays arising together from
a blunt and shortened back-bone, is precisely paralleled
among birds. Thus the ancient birds of the Jurassic rocks,
known under the name of Archeopteryx, had their back-
bone prolonged into a long tail, from each joint of which
there arose a pair of feathers. Such a tail was, therefore,
essentially a fringed one. In modern birds, however, as
we all know, the backbone extends but a short distance
behind the haunch-bone, and then expands into a plough-
share-like bone, from which the feathers of the tail radiate
in a fan-like manner, very similar to the rays of the tail of
a bony fish ; with the exception that whereas in fishes the
fan is placed vertically, in birds it is expanded horizontally.
In many groups of animals besides these we have men-
tioned it appears, indeed, that long tails have gone out of
fashion, as being useless incumbrances. We have instances
of this in the higher apes and bats, in bears, in guinea-
pigs, and in the more specialized kinds of flying-dragons
or pterodactyles.

Having said this much as to the fins of the ancient
fishes, we may conclude this chapter by giving some par-
ticulars relating to the geological history of the Australian
lung-fish, which, from the structure of its fins, we have
already seen reason to regard as one of the most ancient
types of existing fishes. For a number of years there have
been known from the Triassic, or lowest Secondary strata
of Europe, fish-teeth of the pecular type of the one
represented in Fig. 52. The remarkable horn-like form of
the ridges on these teeth suggested the name of Ceratodus
for the otherwise unknown fish to which they pertained.

LUNG-FISHES. 151

Nothing more was discovered as to the nature of this prob-
lematical fish, and it was even doubtful in what position
these teeth were placed in the mouth, or how many of
them there were in each jaw. Thus matters stood till
some twenty years ago, when naturalists were startled by
hearing that a large fish had been discovered living in the
rivers of Queensland, having teeth like these problem-
atical fossils. This fish was no other than the Australian
lung-fish, which, as we have seen, is one of the few living
species still retaining the ancient fringed fins. It was
found that this fish had one tooth on either side of each
jaw, placed in the same position as the figured example ;
and it was naturally considered that the living fish belonged
to the same genus as the Ceratodus of the Trias. Here,
then, we are confronted by the remarkable circumstance
that a kind of fish, first made known to us by fossil teeth
from the very lowest Secondary strata of Europe, was
actually represented by one apparently belonging to the
same genus in the rivers of Australia. It is true, indeed,
that a recent discovery has shown us that the living lung-
fish differs slightly in the structure of its skull from the
fossil Ceratodus, and that the teeth of the opposite sides
of the jaws were not in actual contact with one another,
as were those of the latter. Although these points of
difference are considered sufficient to warrant us in regard-
ing the living fish as not actually belonging to the same
genus as the fossil teeth, yet this does not detract from
the extreme interest of the former as being by far the
oldest type of back-boned animal now living. This type
of fish is, indeed, thus proved to have endured throughout
the whole of the immense period during which the entire
series of Secondary and Tertiary rocks were deposited.
And when we reflect that the Secondary rocks include
those enormous accumulations of strata known as the trias,
lias, oolites, greensands, and chalk, while the Tertiary
comprises the threefold divisions termed Hocene, Miocene,
and Pliocene, we can scarcely fail to be almost lost in
wonder at the prodigious length of time during which
lung-fishes have existed, with but comparatively slight
structural modification. The fossil lung-fishes occur in the

152 THE OLDEST FISHES AND THEIR FINS.

Secondary rocks of Europe, Africa, India, and North
America, and it is an interesting subject of speculation
why the group should have totally disappeared from all
those regions, to find a last home in far Australia.

The existing Australian lung-fish lives mainly or entirely
on leaves, and we may therefore conclude that the fossil
teeth likewise pertained to fishes which subsisted on scme-
what similar nutriment. If, however, we were to infer
that all the teeth of fossil fishes which have a ridged or
flattened grinding surface belonged to the herbivorous type,
we should be sadly in error, simce many of them approxi-
mating more or less markedly to the Ceratodus type really
indicate fishes allied to the well-known Port Jackson shark,
in which the mouth is covered with a complete pavement
of flattened teeth adapted for crushing shell-fish and other
hard animal substances. In all such investigations, the
truth can, indeed, only be found out by careful induction,
and by availine ourselves of every scrap of information
left to us among the relies of former epochs.

LIVING FOSSILS. 153

CHAPTER XV.
LIVING FOSSILS.

In the preceding chapter it was pointed out how that,
through the discovery of the Australian lung-fish, the
ancient Secondary fauna of Europe was brought into much
closer connection with that of the present day than had
hitherto been supposed to be the case. This, however, is
by no means a solitary instance of the discovery in a
living condition of forms of life which have been regarded
as long extinct; and since the subject of the survival of
ancient types in remote corners of the earth or the abysses
of the ocean is one of wide interest, we propose to consider
it in some detail in the present chapter. For such sur-
vivors from a distant past we venture to suggest the title
of “living fossils,” seeing that for the most part they have
but little in common with the dominant fauna of the
greater part of the world; while their alliance with extinct
types is of the most intimate kind. It is, of course,
difficult to know where to draw the line in the use of such
anarbitrary designation; but we shall endeavour to restrict
the term either to types which, although still more or less
abundantly represented at the present day, are of extreme
antiquity, or to such as are now represented by com-
paratively few forms, living either in distant parts of the
world or in the ocean depths, but which were abundant
in pastepochs. Of those coming under the latter category,
the majority, as might have been expected, were first made
known to science from the evidence of their petrified
remains, while their existing relatives were not discovered
till later. Whether, however, the extinct or the living
types were the first to be discovered, the progress of
research has been gradually tending to connect the past
more intimately with the preseut than was originally
supposed to have been the case.

Our first examples of “living fossils” will be taken from

154 LIVING FOSSILS.

the Mollusca, among which the gastropods, described under
the name of pleurotomaria, afford the most striking
instance. The shells of this genus, which are frequently
very elaborately sculptured, have a general external resem-
blance toa Turbo ora Trochus, but are readily distinguished
by a deep horizontal slit in the middle
of the outer wall of the mouth, from
which the genus takes its name. The
: genus Pleurotomaria was originally
\, established in the year 1826 on the evi-
\ dence of a species from the English
lias; and a host of other extinct kinds
xo _canaj) ot Were subsequeutly described, ranging
i nO oe ee the Gluten ao the dalle Pill
1855, no one, however, had the least idea
that the genus was still existing, but in that year a living
specimen was obtained off Mariegalante, which was subse-
quently sold in London in 1875 for £25. The species to
which this first recent specimen belonged was named
P. quoyana; and three examples of the same form have
subsequently been obtained. The next discovery of a
Pleurotomaria occurred in 1861, when an imperfect speci-
men of another species (P. adansonia) was obtained. A
second example of this same species was taken in 1882
near Guadaloupe, and three others are in existence, while
a seventh was purchased in 1890 at Tobago. The latter
example was a very large shell, measuring just under six
inches in height; and it was also distinguished by its
striking coloration, being marked by a number of oblique
splashes of reddish-orange on a pale flesh-coloured
ground. <A third species of the genus (P. beyrichi) was
obtained from Japanese waters in 1877, and three
examples have been subsequently secured. Finally, the
fourth and largest living species is only known by a
single example, which was recognized in 1879 among a
collection of shells at Rotterdam, and is believed to have
come from the Moluccas. The height of this fine shell is
six and three-quarter inches.
It will thus be apparent that only fourteen specimens of
living Pleurotomariz, referable to four distinct species,

TRIGONIA. 155

are at present known. These molluscs, which inhabit
deep water on rocky bottoms, must therefore be extremely
rare, although from the nature of their habitat it is
probable that not so many specimens are obtained as
might otherwise be the case. In the Tertiary period only
eleven species are known, of which two are from the
Pleistocene, two from the Miocene, and seven from the
Eocene. Directly, however, we reach the Cretaceous, the
number of species suddenly leaps up to 208, while the
total number of Secondary and Palzozoic species is upwards
of 1145. Accordingly, out of a total of 1160 representa-
tives of the genus, only fifteen are of post-cretaceous age,
of which but four now exist, and these apparently poorly
represented in individuals. Here, then, we have indeed a
striking instance of a “ living fossil.”’

The well-known bivalve shells named Trigonia afford a
scarcely less well-marked case of the persistence of early
types. This genus was originally named in 1791, on the
evidence of an extinct species, but when fully described
by Lamarck in 1804 some few recent living examples had
also been obtained. For the benefit of those of our readers
who may not be familiar with these molluscs, it may be
mentioned that the living Trigoniw are rather small shells,
of about an inch and a half in diameter, characterized by
their somewhat triangular shape, and the strongly-marked
transverse ribs, marked with rough tubercles on the outer
surface. Internally the shell has a polychroic pearly
lustre ; while the peculiarly-shaped and striated inter-
locking hinge, when once seen, can never be mistaken. At
the present day the Trigonix are represented only by some
five closely allied species or varieties, confined to the
Australian seas; while in the Tertiary, although more
widely distributed, they were likewise rare. In the Secon-
dary period, where they range down to the lias, these
shells were, however, extremely abundant, and attained
far larger dimensions than their existing relatives. Indeed,
in the oolites Trigoniz were some of the most common
molluscs, whole slabs of rock being sometimes found
paved with their handsomely sculptured shells, while ail
who have visited the Isle of Portland must be familiar

156 LIVING FOSSILS.

with the countless swarms in which casts of their shells
occur in the so-called “roach-bed” of the quarrymen.
The survival of Trigonia in the Australian seas alone
affords a curious parallel to the persistence of pouched
mammals and monotremes on that island-continent, and
of the lung-fish in its rivers.

The pearly nautilus, of which there are some three or
four species from the warmer seas, is likewise entitled to
oceupy a place among “living fossils,” since this group of
cephalopods has existed continuously to the present day,
from the epoch of the lower Silurian, with a progressive
diminution in the number of species. It was long con-
sidered that the Paleozoic nautili were congeneric with
the existing ones, but although this is probably not the
case, the whole are so closely allied as to show a most
remarkable persistence of type throughout untold ages;
nautili have, indeed, witnessed the incoming and the
decline of the whole group of ammonites, so characteristic
of the Secondary rocks; but the reason of the persistence
of the one type and the total extinction of the other type
appears entirely beyond our ken.

The most remarkable instance of the persistence of type
is, however, afforded by the genus Lingula among the
brachiopods, or so-called lamp-shells. Lingulas have
oblong, flattened, and somewhat nail-like shells, composed
partly of horny and partly of calcareous matter, and are
attached to foreign substances by a long muscular pedicle
passing out between the beaks of the two valves, which
are generally of a greenish hue. These molluscs range
from the Cambrian—at the very base of the Paleozoics—
to the present day, without any trace of generic modifica-
tion, and indeed with no perceptible change. Moreover,
the group seems to be now as well represented in species
as ever it was, the total number of living forms being
given in the second edition of Woodward’s ‘‘ Mollusca”
as sixteen, while the total of fossil species at that date was
but ninety-one. The lingulas are, therefore, the very
oldest animals at present im existence. They are, how-
ever, run somewhat close by two other genera of brachio-
pods respectively known as Discina and Crania, both of

STONE-LILIES. 157

which range from the lower Silurian or Ordovician epoch
to the present day. The parallelism in this respect is not,
however, so close as it might at first sight appear, since the
lower Palzozoic representatives of both the latter genera
are subgenerically distinct from their living analogues.
While the first of these two genera has some ten living
species, the latter possesses but five, and both had a large
number of Paleozoic representatives.

It is, perhaps, almost superfluous to add that the whole
of the brachiopods are a waning group, although the types
known as rhynchonellas and terebratulas have been ascer-
tained, of recent years, to be more numerously represented,
both as regards species and individuals, than was formerly
considered to be the case.

The so-called stone-lilies, or crinoids—near relatives of
the familiar star-fish, but attached, in the young condition
at least, to the sea-bottom by a jointed stem—likewise
constitute a group in which by far the greater number of
types are totally extinct, although a few survive to merit
the title heading the present chapter. The stone-lilies are
divided into two primary groups, one of which is totally
extinct, while the other, which does not extend backwards
beyond the Secondary period, comprises the few existing
representatives of the class. The genus which may be
selected as especially worthy of the designation “living
fossil” is Pentacrinus, so named from the pentagonal form
of the discs of the stalk—so familiar to all who have
studied the fossils of the British Secondary rocks. ‘The
pentacrinids were originally named on the evidence of
certain species from the British lias, which attained a
height of several feet, and flourished in extraordinary
profusion on the old sea-bottom, as the reader who cares
to pay a visit to the fossil galleries of the Natural History
Museum may see for himself. For some time the group
was only known from the Secondary rocks, but eventually
a minute species (P. europeus), supposed to belong to it,
was found living in deep water off the Irish coast ; while
in 1755 a much larger form (P. caput-meduse) was dis-
covered in the We.t Indian seas. The former turned out,
however, to be merely the larva of the familiar feather-star

158 LIVING FOSSILS.

(Antedon) ; although the latter, together with many other
subsequently discovered species, was a true crinoid. For

a long period these living crinoids were supposed to be of

Fic. 54—A Living Pentacrinid.

extreme rarity, only a few examples being from time to
time procured.

With the development of deep-sea

FISHES. 159

dredging it was, however, found that pentacrinids were
really abundant in certain localities, and several new
species (one of which is represented in the accompanying
figure) have been named of late years. Thus in the
summer of 1870, Gwyn Jettreys dredged up quantities in
the Atlantic; while in the neighbourhood of the Aru Islands
Moseley tells us that during the voyage of the Challenger
more than thirty specimens of Pentacrinus were taken
at a single haul of the dredge in 500 fathoms of water.
Although their pyritized remains, which are so common on
the slabs of lias, would have indicated that these crinoids
must have been creatures of extreme beauty, no adequate
idea of their gracefulness would ever have been obtained
had the group not been represented in the living state.

Pentacrinids are, however, by no means the only “living
fossils ” belonging to this class of animals. For instance,
the smaller and simpler Rhizocrinus of the Atlantic is a
survivor from the Eocene ; while both this genus and the
allied Buthycrinus, from depths reaching to 2400 fathoms
in the Atlantic, are near relatives of the extinct Bourgueti-
crinus of the chalk. Moreover, all these forms are related
to the so-called pear-encrinites (Apiocrinus), so common
in the middle Jurassic rocks of Europe; while these,
again, lead on to the still earlier lily-encrinites (Encrinus)
of the trias.

If space permitted, there are several other groups of
invertebrates which might claim our attention, but we must
pass on to the vertebrates. Among the fishes the one
which has the greatest claim to the title of a “living
fossil” is the aforesaid Australian lung-fish of the rivers
of Queensland. As mentioned in the last chapter, teeth
of fishes allied to the Australian lung-fish have been long
known from the Secondary rocks, ranging downwards to
the trias, and occurring in Europe, India, Africa, and
North America. These teeth were, indeed, first described
by Agassiz as far back as the year 1838; and the group
was believed to be extinct till 1870, when one of the two
living forms was discovered. At first, as stated in the
same chapter, it was believed that the latter were
generically identical with the fossil, Ceratodus, but it has

160 LIVING FOSSILS.

been ascertained recently that there are certain slight
differences which justify the separation of the living species
as a distinct genus. At present we have no decisive
evidence of the existence of these fishes between the upper
Jurassic of the United States and the Pleistocene of
Queensland, so that there is a long gap in their history to
be filled up, it may be boped, by future discoveries.

The Australian lung-fish is, however, but one of three
nearly allied genera, of which the other two (Lepidosiren
and Protopterus) are each represented by a single species,
severally inhabiting the Amazon and the rivers of West
Africa. These three widely separated forms are, then, the
sole living representatives of an extensive order which was
once widely distributed over the globe, and has been slowly
waning ever since the Paleozoic period. The group is one
of especial interest, since from some of its extinct re-
presentatives, or nearly allied fishes, it is probable that
amphibians, and hence the higher vertebrates, have all
been derived.

Of nearly equal interest with the lung-fishes are the
bony pikes (Lepidosteus) of the rivers of North America
and the bichir (Polypterus)* of the upper Nile and the
rivers of Western Africa; which, together with another
West African form (Calamo/chthys), are the sole existing
representatives of the mail-clad ganoid fishes so abundant
during the Secondary period. The African forms are at
present unknown in the fossil state, but the bony pikes
date from the lower Eocene, and thus indicate continuity
with the extinct Secondary types.

Another living fossil among fishes is the well-known
Port Jackson shark (Cestracion), the last survivor of a
genus ranging in the Secondary rocks of Europe down to
the Kimeridge clay ; and also the sole living member of a
vast group of sharks characterized by the pavement of
crushing teeth with which the mouth is covered. As
remarked long since by Buckland, cestraciont sharks lived
side by side with trigomas in the old Jurassic seas of
Europe; and it is not a little remarkable to find the

* See page 145.

REPTILES. 161

same comradeship still kept up on the distant coasts of
Australia.

Quite recently another link connecting the present
fauna of Australia with that of Secondary Europe has been
discovered. For a considerable time a peculiar group of
herrings (Diplomystus), characterized by having a row of
scutes on the back resembling those found in other types
on the opposite aspect of the body, have been known from
Cretaceous and early Tertiary rocks, their range including
Brazil, Wyoming, the Isle of Wight, and the Lebanon.
Till the other day, these doubly-armoured herrings were
considered to be totally extinct, but now, lo and behold!
they have turned up alive in certain rivers of New South
Wales.

Among amphibians, the creature which seems best
entitled to be called a “living fossil” is the giant
salamander (Cryptobranchus) of Japan, since, together
with a smaller North American kind, it is the representa-
tive of a genus once common in Europe during the middle
portion of the Tertiary period. Indeed, our first know-
ledge of the group was derived from a fossil specimen of
one of these salamanders from the continent, described in
the year 1726 under the title of homo diluvii testis, in the
belief that it was a human skeleton!

Passing on to the reptilian class, we have to notice that
in the year 1842 Sir R. Owen described from the Triassic
rocks of Shropshire the remains of a small lizard-like
reptile (Rhynchosaurus), differing from all living forms in
the structure of its skull, of which the jaws terminated
in a peculiar beak. Eleven years previously Dr. Gray
had, however, applied the name Sphenodon to a then very
imperfectly Inown living reptile from New Zealand;
which when fully described by Dr. Giinther in 1867
turned out to be very closely related to the Triassic
Rhynchosaurus. Although externally somewhat like a
lizard, but with a different kind of skin, the tuatera, as
the New Zealand reptile is called, differs entirely in the
structure of its skull and skeleton in general from the
true lizards, and comes much closer in these respects to
crocodiles and tortoises. Subsequent researches have

M

162 LIVING FOSSILS.

brought to light the existence of the remains of a large
number of more or less nearly allied reptiles in the
Secondary rocks of Europe and other parts of the world.
Accordingly the tuatera, which, although not generically
identical with any one of these extinct forms, has every
right to be regarded as a ‘‘ living fossil”; while it enjoys
the further distinction of being, with the exception of
the lancelet, the only vertebrate animal which can be
definitely regarded as the sole living representative of a
distinct order.

Since birds have no species with any very great claim to
be mentioned here, we pass on to mammals, of which our
notice must necessarily be brief. In a previous chapter
it has been stated that certain remarkable Secondary
European and American mammals appear to be related
to the ege-laying mammals of Australia and New Guinea ;
and we may, therefore, assume that the latter, as their
structure indicates, are very ancient types, although their
direct ancestors have not yet been discovered. The banded
anteater (Myrmecobius) and the bandicoots (Perameles) of
Australia seem to be the nearest relatives of another great
group of Secondary mammals, and are therefore probably
some of the oldest types with which we are yet acquainted,
although here again their exact genealogy is at present
unknown. No other groups of living mammals are yet
definitely known to have existed before the Tertiary period,
and the pedigree of the class in general is consequently
brief as compared with that of many of the animals
discussed above. The opossums (Didelphys) are, however,
perhaps those mammals best entitled among the Tertiary
groups to the appellation of “living fossils,” as they have
existed without generic modification since the period of
the Eocene, and have now entirely vanished from their
old European haunts to maintain an existence in America,
where they are mainly characteristic of the southern half
of the continent. Although the insectivores and the
lemurs are evidently primitive types, but few of their
existing genera date far back in the Tertiary period, while
in the latter group nota single existing genus is known
before the present epoch. None of these mammals

MAMMALS. 163

properly come, therefore, within the scope of the present
chapter. On the other hand, tapirs and rhinoceroses, as
dating from the lower part of the Miocene or the upper
portion of the Eocene period, might be considered to claim
notice in our survey, while the same remark would apply
to the civets of the genus Viverra. Since, however, these
mammalian types are comparatively well represented at
the present day, they scarcely come under the designation
of “living fossils.’ There is, however, one mammal to
which this title is strictly applicable, namely, the water-
chevrotain of Western Africa. This genus of mammals
was originally made known to science upon the evidence
of fossil remains from the Pliocene rocks of Darmstadt
described under the name of Dorcatheriwm in 1836. Four
years later, a living uneulate from West Africa was
described as a species of musk-deer (Moschus), and the
same creature was in 1845 made the type of a new
genus, Hyomoschus. Subsequently other extinct species
of Dorcatherium were described from the Miocene rocks
of Europe and the Pliocene of India, and it was eventually
proved that the African water-chevrotain belonged to the
same genus as these reputedly extinct forms. Hence, the
animal in question, as being the sole existing representa-
tive of a genus which had formerly a comparatively wide
distribution and which was originally described as extinct,
has the most indisputable claim to rank as a “living
fossil.”’

m2

164 THE EXTINCTION OF ANIMALS.

CHAPTER XVI.
THE EXTINCTION OF ANIMALS.

Ir it be true that, as compared with the pre-glacial epoch,
we are living in an impoverished world so far as the larger
forms of animal life are concerned, it is even more certain
that our immediate descendants will be the heirs of a
still more depopulated globe. Already the bison has
disappeared from the Americar prairies, while of the vast
swarms of antelopes and other large mammals which half
a century ago peopled the plains of Africa scarce a tithe
remains, and a few are well-nigh, or even totally, extinct.
A few years ago, indeed, it appeared that we were likely
ere long to witness the complete extermination of many
species of the larger African mammals; but, although we
can never expect to see them again in their original
multitudes, several of the South and Hast African govern-
ments are now taking measures to ensure the preservation
of a few of the various species, and there is accordingly
some hope that although the nineteenth century will ever
deserve the reproach of posterity, as having been the one
during which the world was to a great extent depopulated
of the larger forms of animal life, yet that it will escape
the crowning shame of having actually exterminated a
host of species. Still, however, the indictment against our
generation is heavy enough in all conscience ; and there is
no reasonable doubt but that the destructiveness which is
so characteristic of human nature—whether civilized or
otherwise—has led to the total extinction of two species
of large African mammals within the last thirty years,
while a third is only too likely to share the same fate. On
the other hand, it must not be assumed that all the
animals known to have become extinct within the historic
period have succumbed directly to this demon of destruc-
tiveness, In certain cases, as we shall see in the sequel,
the introduction of other animals by human agency has

MAMMALS. 165

been the involuntary means of leading to the final
extinction ; while occasionally, as in the case of the great
auk, a catastrophe of nature has accelerated the climax.
In other instances, it would seem that a species has been
gradually dying out from unknown natural causes, in the
manner which appears to be natural to all forms of animal
life, where species and genera, like individuals, have but a
certain allotted span of existence.

In the present chapter we propose to notice the chief
animals, exclusive of invertebrates, which are known to
have been exterminated, or are just verging on extinction,
within the historic period ; but before doing so we may
briefly allude to a few others which urgently require pro-
tection, unless they are to share the same fate. Foremost
among these are the African elephant and the so-called
white, or square-mouthed, rhinoceros of the same country.
Till within a short time ago there were, indeed, strong
grounds for believing that the latter magnificent animal,
which at present is represented only by a few skulls and
horns in English collections, had already disappeared ; but
we are rejoiced to hear that a few individuals still linger
on in a remote corner of Eastern Africa, where it is to be
hoped they will receive immediate and adequate protection.
The walrus of the polar regions is another animal whose
numbers have been woefully diminished of late years, and
which likewise stands in urgent need of protective legis-
lation, while a similar remark will apply to several species,
or local races, of seals. In countries like New Zealand.
where there were originally no native carnivorous animals,
many of the indigenous creatures now stand in great
jeopardy by the introduction of the latter, and it is only
too likely that the flightless kiwis of those islands will
eventually be exterminated by half-wild cats and dogs.
The curious tuatera lizard of the same country is also
likely to be killed off by pigs.* In the Samoan Islands a
similar fate long threatened the tooth-billed pigeon
(Didunculus)—the nearest living ally of the dodo—but
the impending destruction was fortunately averted by the

* See page 161.

166 THE EXTINCTION OF ANIMALS.

bird having forsaken its original habits and taken to
perching on trees.

Strictly speaking, the moas of New Zealand come w ithin
the category of animals exterminated within the historic
peviod, since they were almost certainly killed off by the
Maories ; but as we have no direct historic evidence of
their existence, no further mention of them will here be
made. We shall commence our survey with three species
which were the first to succumb.

When the Dutch Admiral Van Neck visited Mauritius
in the year 1598, he found that island inhabited by a
number of ungainly, flightless birds, which he called
walghvogel (disgusting fowl), but which were afterwards
termed by the Portuguese dodo (from dowdo, a simpleton).
Subsequently, many living examples of this bird (the form
of which is probably well known to our readers) were
exhibited in Holland, and their portraits painted by the
two artists Savery. The museum at Oxford also once
_ possessed a stuffed specimen, which, with the exception of
the head and a foot, were in 1755 destroyed, as being
too much decayed to be worth preserving! In the year
1601 a Dutch ship captured twenty-four dodos for pro-
visions, and others soon followed suit, so that at this time
the bird was still common. It had, however, disappeared
before the close of the century. The last notice of the
living bird occurs in the journal of the mate of the Berkley
Castle in 1681; and from the absence of any mention of
it by Leguat, who visited the island in 1693, we may
presume that it was already quite extinct. Although the
numbers carried away by ships doubtless largely aided in
its extermination, Prof. Newton is of opinion that the
dodo was finally killed off by the pigs which had run
loose over the island. There is evidence that an allied,
although totally unknown bird formerly inhabited the
neighbouring island of Réunion.

Near akin to the dodo was the taller and more lightly-
built pigeon-like bird formerly inhabiting the island of
Rodriguez, and known as the solitaire (Pezophaps). Our
sole knowledge of this bird in a living state is derived
from the accounts of Leguat, who founded a colony on the

BIRDS AND RHYTINA. 167

island in 1691, and who has left us not only a good
account of its habits, but likewise an excellent portrait.
When the solitaire became extinct is uncertain, but there
is some evidence that it may have lingered on in the more
remote parts of the island down to the year 1761. These
birds were flightless, and the males much larger than the
females, their rudimentary wing having a peculiar horny
ball-like excrescence. Up to the year 1864 our museums
possessed only a few bones of these strange birds, obtained
from caverns in Rodriguez; but during the transit of
Venus expedition a large number of remains were obtained,
from which several more or less nearly perfect skeletons
were set up.

Mauritius and Rodriguez also possessed another large
flightless bird, known as the Aphanapteryz, and belonging
to the rail family. By the fortunate discovery of an old
painting, we learn that this bird hada long recurved bill
and a brownish-red plumage. It was living in 1615, but
seems to have disappeared by Leguat’s time.

Another extinct Mauritian bird was the géant (Lequatia),
which was a kind of cvot, described by Leguat in 1695 as
being equal in size to a goose. When it died out is
unknown. <A remarkable crested parrot (Lophopsittacus)
—the sole representative of its genus—also existed in
Mauritius in 1601, which has long since disappeared.

Our next instance of extermination relates to a very
different kind of creature, viz., the great northern sea-cow
(Rhytina), a near ally of the existing dugongs and manatis
of the warmer seas. The rhytina, which was far larger
than its living cousins, attaining a length of from twenty-
four to thirty feet, was discovered by the ill-fated navi-
gator Behring, on the island which bears his name, in the
year 1741; and had it not been that he was accompanied
by an excellent naturalist (Steller), it is quite probable
that the creature might have perished without our ever
having even heard of its existence. This sea-cow was con-
fined to Behring and Copper Islands at the date of its
discovery, where it existed in large numbers ; but there is
little doubt that it must formerly have had a much wider
range, and that it was even then a waning race. Although

168 THE EXTINCTION OF ANIMALS.

Behring and his party were

wrecked on Behring Island,

where they remained for some
; ten months, it does not appear
that they inflicted much damage
on the sea-cows ; but soon after,
various fur-hunting expeditions
were fitted out to Alaska, the
members of which depended
solely on these animals for food.
So incessant, indeed, was the
persecution of the unfortunate
creatures, that by 1754 they had
been exterminated on Copper
Island, while by 1763 nearly all
had been killed on their other
haunt, and the last individual of
their race is supposed to have
perished either in 1767 or the
following year. Up to 1883 three
skeletons in foreign collections
and a few ribs in the British
Museum were all that remained
of the rhytina; but since that
date numerous remains have
been obtained from the peat of
Behring Island. Fortunately,
the excellent description left by
Steller, and some drawings which
have come down to us from the
navigator of Behrine’s party,
give us a very good idea of the
external form of the giant sea-
cow.

Continuing our chronological
survey, the next exterminated
animals that claim our atten-
tion are the gigantic land
tortoises of the Mascarene
Islands, that is to say Mauri-

Skeleton of the Northern Sea-Cow.

6-9

———

HIG, 00.

PON

Se

= ee

recer “s

Cee

GIANT TORTOISES. 169

tius, Rodriguez, and Réunion. In Mauritius these
tortoises were first discovered by Van Neck, the discoverer
of the dodo, in 1529, who relates that some of them were
of such huge dimensions that six men could be seated on
their shells. In Reunion, the voyager Boutehoc writes
that he took twenty-four giant tortoises from beneath a
single tree, in the year 1618; while Leguat, in 1691, states
that in Rodriguez “there are such plenty of land-turtles in
this isle that sometimes you see two or three thousand of
them in a drove, so that you may go about a hundred
paces on their backs.’”’ The Réunion tortoises, of which
not a single specimen remains in our museums, seem to
have been the first to disappear, although at what date is
uncertain. A solitary individual apparently, however,
survives at Mauritius, where it has lived for considerably
more than a century, having been imported from the
Seychelles, where it was doubtless carried from Réunion.
Down to the year 1740 these reptiles were still abundant
in Mauritius, but by 1761, when vessels were employed in
transporting them to that island from Rodriguez as food,
they had probably become scarce ; while in both islands
the whole race became extinct early in the present century,
mainly owing to the ship-loads which were carried away
for food; although rats and pigs have largely aided in the
work of destruction by devouring the eggs and young. It
may be added that giant tortoises were formerly widely
distributed over the world; but that within the historic
period they have existed only in the Mascarenes, in
Aldabra, to the north of Madagascar, and in the far distant
Galapagos group. In Aldabra, whence they have been
introduced into the Seychelles, they are now becoming
very scarce, although we believe they receive some kind of
protection. The Galapagos tortoises are, however, only
too likely to share the fate of those of the Mascarenes,
most of the larger specimens having been already killed
off. Indeed, it is highly probable that the Abingdon
tortoise, remarkable for the extreme thinness of its
shell, specimens of which were obtained in 1875 for our
national collection, may already be numbered with the
extinct.

170 THE EXTINCTION OF ANIMALS.

With the pied starling (Fregilopus varius) of Réunion
we return once more to birds. This beautiful species, the
sole representative of its genus, and distinguished not
only by its pied plumage but likewise by the presence of
a crest of feathers on the head, is said to have been very
bold and confiding in its disposition, and is believed to
have been exterminated about fifty years ago.

Within the last few years a species of ke-ke parrot
(Nestor productus), formerly inhabiting Phillip Island,
near New Zealand, is likewise believed to have become
extinct about the middle of this century.

Our next species is one which may possibly be still
existing, although, if so, it must be of extreme rarity.
This is the gigantic blue coot (Notornis mantelli) of New
Zealand, which is almost the sole representative of its
genus, although it has near allies in the purple water-
hens (Porphyrio). This huge flightless bird was first made
known to science on the evidence of some bones obtained
from the voleanic sands of Waingongoro, in the North
Island, and described by Sir R. Owen as belonging to an
extinct form. Their discoverer, Mr. W. Mantell, succeeded,
however, in obtaining the skin of an example which had
been caught alive and eaten by some sealers in the South
Island, some time in 1877; this skin, together with that of
the second specimen, being now mounted in the British
Museum. The second living specimen was taken in 1869,
and a third in 1881, both in the South Island; but whether
any others still survive is more than doubtful. As the
fossilized remains of this species are not uncommon in
the superficial deposits of both islands, we may probably
refer its extinction in the North Island, and its extreme
rarity in the South, to the Maories. If it still linger it is
probable that wild pigs, dogs, or cats will ere long put
a term to its existence. An allied species (WN. albus),
distinguished by its plumage, formerly inhabited Norfolk
and Lord Howe Islands, but is now extinct.

The great auk, or gare fowl, brings us to a species
completely exterminated in modern times, and of which
the accounts are fairly complete. This bird, the largest
member of its genus, and totally unable to fly, was

GREAT AUK. 171

restricted to the shores of the North Atlantic, ranging in
Europe from Iceland in the north to the Bay of Biscay in
the south, while in America it extended from Greenland
to Virginia. These southern limits mark, however, only
the winter range of the species, which was somewhat
migratory in its habits. Its breeding-places were but few,
the chief being the rock called Geirfuglasker off the coast
of Iceland, and Funk Island on the Newfoundland coast ;
both these spots being bare, barren rocks very difficult of
access. In spite of its slow increase (but a single ege being
laid at a time), the great auk existed in countless numbers
on Funk Island, where it was discovered by Cartier in 1584.
Here for nearly two centuries it formed an unfailing food-
supply for all vessels visiting the neighbouring seas; and
it might bave lived till now had not the custom arisen of
men being landed on the island to spend the summer in
slaying these birds for the sake of their feathers. It is
said, indeed, that the auks were actually killed by millions,
being first driven intostone enclosures, and then bludgeoned.
When the bird disappeared from the American side is not
quite clear, although it was probably somewhere about the
year 1840. Four years later it had also ceased to exist
on the opposite side of the Atlantic, the last European
pair having been killed in the summer of 1844. What
led to its rapid and final extermination in Europe was
the sudden subsidence of the Geirfuglasker in 1830,
which compelled the birds to seek other and more
accessible breeding-places, where they were less protected
from molestation. The last British example was killed in
Waterford harbour in 1834. In addition to bones obtained
from Funk Island, the great auk is now represented in
collections only by some seventy-six skins, nine skeletons,
and sixty-eight e¢o-shells.

Before noticing the few remaining birds on our list, we
may refer to two South African mammals which are now
almost certainly extinct. The first of these is the fine
antelope known as the blaubok (Hippotragus leucophceus),
a near ally of the handsome sable antelope and roan
antelope, characterized by their large scimitar-like and
backwardly-sweeping horns. Indeed, the roan antelope

172 THE EXTINCTION OF ANIMALS.

is often confounded with the blaubok, although the latter
was a considerably smaller and otherwise different species.
When the blaubok was killed off cannot now be ascertained,
but it was certainly abundant at the Cape in the first half
of this century. Unfortunately, the British Museum has
not a single specimen of this antelope, although a head
is preserved in Paris.

The second African mammal is the quagga (Equus
quagga), w near relative of the zebras, but distinguished by
the hinder portion of the body being devoid of stripes.
This animal was described by Sir Cornwallis Harris in
1839 as existing in immense herds, although its distribution
was always very local; but of late years there is no definite
record of a single specimen having been seen. If, as is
probably the case, it is truly extinct, there is no record of
the date of its disappearance. Of the almost total ex-
termination of the square-mouthed rhinoceros, mention
has been already made.

Curiously enough, the northern sea-cow was not the
only animal discovered on Behring Island in 1741, during
Behrine’s involuntary sojourn, which appears to have
since become extinct. This second species was Pallas’s
cormorant (Phalacrocorax perspicillatus), the largest repre-
sentative of its genus, and distinguished by its lustrous
green and purple plumage, and the bare white spectacle-
like rings round the eyes. This bird, which weighed from
twelve to fourteen pounds, had small wings and was a
poor flyer, with a stupid, sluggish disposition. Steller
relates that it occurred in great numbers, and was exten-
sively used as food by the members of Behring’s party.
About 1839, Captain Belcher, of the “Sulphur,” received
as a great rarity a present of one of these fine birds from
the Governor of Sitka, by whom some other specimens
were sent to St. Petersburg; but since that date nothing
has been heard of the species, which probably became
extinct within about a century of its discovery. Dr.
Stejnegar, who visited Behring Island in 1882, instituted
a careful search after this bird in vain, although he was
rewarded by finding some of its bones buried in the soil.
The species is now represented only by four mounted

MAMO AND LABRADOR DUCK. 173

specimens, one of which is in our own national collection,
and a few bones.

Another bird that appears to have become extinct within
the last half-century is the beautiful black and golden
sickle-bill, or mamo (Drepanornis pacifica), first brought to
Europe by Captain Cook after his discovery of the Sand-
wich Islands, to which group it was restricted. This bird
belonged to the family of honey-suckers, and was remark-
able for the length of its curved bill. The brilliant yellow
feathers from the back of the bird were used by the
Hawaiian chieftains im the manufacture of their gorgeous
feather-cloaks; and as one particular cloak, according to
Mr. Scott Wilson, measures four feet im length and more
than eleven feet round the base, it may be imagined what
a number of birds of eight inches in length—and these
only yielding the particular feathers on the back—would
be required for its construction. Indeed, the manufacture
of this particular cloak is stated to have lasted through
the reigns of eight chieftains; and it is to the destruction
thus caused that Mr. Wilson attributes the extinction of
this beautiful bird, now represented in our museums only
by some four stuffed examples.

In the Antilles a remarkable burrowing petrel, known
as the diablotin, is also believed to be now extinct.

With the handsomely marked Labrador duck (Somateria
labradorias), a near ally of the eider-duck, we bring to
a close our list of animals which can be pretty definitely
affirmed to be extinct, although there are a few others
over which the same fate is impending, even if it has not
already befallen them. This duck was not unlike the
common long-tailed duck (Harelda glacialis) in general
coloration and size, although without the long tail of the
latter. In the male, the body and primaries are black, and
there is also a ring round the neck and a stripe down the
head of the same hue; while all the remainder is white.
During the breeding-season this species inhabited
Labrador, but in winter its range extended as far south as
New Jersey. According to Mr. F. A. Lucas, to whom we
are indebted for much information concerning the extine-
tion of several of the species noticed in this chapter, the

174 THE EXTINCTION OF ANIMALS.

Labrador duck was never common, and as no example has
been seen since 1879, it may fairly be presumed to be
extinct.

In conclusion, we may refer to a very remarkable
mammal of which but a single example has hitherto come
under civilized human ken. As most of our readers are
probably acquainted, at least by name, with the large
spotted South American rodent, known as the paca—a
distant cousin of the familiar guinea pig—we shall assume
that they know what we mean when we talk of a paca-like
animal. Now, ona certain occasion, somewhat more than
twenty years ago, the inhabitants of Montana de Vitoc, in
Peru, were surprised to find at daybreak a large rodent
with the general appearance and coloration of a paca
walking unconcernedly about the courtyard of a house.
The creature differed, however, from a paca in having a
tail of considerable length, as well as in its smaller ears
and cleft upper lip; while dissection revealed other internal
points of distinction. The curious part of the matter is
that none of the natives of Peru had ever previously heard
of or seen a similar animal (for which, by the way, the
name of Dinomys was suggested), and from that day to
this nothing more has been heard about the creature.
Can it be that the specimen then seen and killed was the
last survivor of its race, and that the Dinomys, whose
existence was thus strangely revealed to us, must also be
nwubered with the extinct ?

PROTECTIVE RESEMBLANCE IN ANIMALS. 175

CHAPTER XVII.
PROTECTIVE RESEMBLANCE IN ANIMALS.

Tuat the colours of animals tend to assimilate themselves
to the natural surroundings of the animals themselves is
a fact which has long been known in natural history; and
it is, indeed, one which is self-apparent to every sportsman
and to every traveller in the wilder regions of the globe.
For instance, everyone is probably aware that desert-
haunting animals, like lions, gazelles, wild asses, jerboas,
and many species of birds, generally have a uniform
sandy-coloured coat, which renders them at a short distance
almost or completely invisible im their native wastes.
Then, again, every English sportsman knows how com-
pletely the coloration of the partridge and the hare assimi-
lates with that of the stubble or ploughed fields in which
they are wont to lie; while the mottled blacks and browns
of the woodcock and snipe accord so exactly with the hues
of decaying leaves and grass that the inexperienced eye
will often fail to detect a wounded bird even when lying
close to the feet, and scarcely anyone can distinguish
the living birds when on the ground. The brilliant
vertical orange and black stripes of the tiger and zebra,
when seen in a menagerie or a museum, do not strike us as
resembling anything in inanimate nature. In its native
jungle, largely composed of upright yellow stems of tall
erasses, between which are narrow intervals of deep black
shade, the colour of the tiger is, however, admirably
suited to its surroundings ; and it is stated that the stripes
of the zebra are arranged in such proportions as exactly to
match the pale hue of arid ground by moonlight, so that
on such occasions these animals are alsolutely invisible
even at very short distances, while they are by no means
easy to distinguish at a moderate distanve even in broad
daylight. We hardly need refer to the white colour of
polar animals, such as bears, ermines, foxes, hares, &c.,

176 PROTECTIVE RESEMBLANCE IN ANIMALS.

as the most perfect example of this kind of protective
coloration ; and numerous other examples will at once
present themselves to the reader.

Well known as are these comparatively simple instances
of protective resemblances, there are, however, others of
a more striking nature, where the animal either resembles
the form of some inanimate object, or that of some other
kind of animal which has especial means of protection ;
and since these resemblances are less generally known,
they will form the subject of the present chapter. The
term “protective resemblance” is generally applied to those
instances where the animal resembles more or less closely
an inanimate object, and thus renders itself inconspicuous ;
while the instances where one animal assumes the appear-
ance of another, and thereby becomes conspicuous, are
classed under the term “ mimicry.” It will, however, be
obvious that both these kinds of resemblances are near
akin, and are far in advance of protective coloration, pure
and simple, where no imitation of form takes place. We
shall first mention some instances of the imitation of the
forms of inanimate objects by animals, and then refer
to those cases where other animals are the objects of
imitation.

Some of the best examples of what we shall take leave
to call inanimate mimicry are to be found among insects,
and we shall take our first case from among the butter-
flies. All are probably aware that a large number of these
insects, such as our common peacock and tortoiseshell
butterflies, while brilliantly coloured on the upper surfaces
of their wings, have the under surfaces of the same of a
dull, sombre hue; and most of us have doubtless been
almost startled at the suddenness with which one of these
gaudy creatures seems to vanish altogether when it settles
on dark ground or the rough bark of a tree, and at once
closes its wings. Here, then, we have an instance of
ordinary protective coloration, without any attempt at
mimicry of form. There is, however, a peculiar group of
butterflies allied to our own purple emperor, inhabiting
northern India and the Malayan region, which have gone
far beyond this simple kind of protective resemblance,

yy

LEAF-BUTTERFLY. 177

and actually imitate the form of leaves growing on their
native brauches. These butterflies (scientifically known
as Callima) have the upper surface of the wings brilliantly
marked with orange, their front wings terminating in a
sharp point externally, and the hind ones ina “tail,”
after the fashion of our swallow-tailed butterflies. Between
the sharp point of the front and the tail of the hind wing
there runs on the under surface a curved line, from which
smaller lines are given off to the edges of the wings.
When this butterfly settles on the stem of a plant bearing
pointed leaves, and closes its wings, the points and tails of
the same of course come into exact opposition ; and since
the tail of the wings is closely applied to the stem of the
plant it appears exactly as though it were the stalk of a
leaf, the midrib and veins of which are exactly imitated
by the lines on the under surface of the wings; while the
apex of the leaf is formed by the opposed points of the
front wings. So exact is the resemblance of the butterfly
when in this po-ition to a faded leaf, that, as Mr. Wallace
tells us, it deceives the eye even when gazing full upon it,
and without actually seeing the insect settle upon the spot
it is absolutely impossible to find it. To increase the
delusion no two individuals of these *nsects are precisely
alike on the under surface ; while many of them have little
black patches, or dots, exactly resembling the dark fungous
growths so often found on decaying leaves. Fortunately
for the reader who desires to verify this extraordinary
instance of inanimate mimicry, a case is now exhibited in
the central hall of the Natural History Museum with
several of these insects attached to a bough with faded
leaves, and it is curious to watch the visitors to this case
and see how often they fail to distinguish all the butter-
flies from the leaves which they imitate.

The next best instance of inanimate mimicry among
insects occurs in the so-called stick- and leaf-insects, which
are allied to our grasshoppers and cockroaches. The
stick-insects, some of which are found in southern
Europe, have long, slender bodies and limbs, of a dark
colour, and so exactly resemble dry sticks that it is almost
impossible to distinguish between the one and the other.

N

178 PROTECTIVE RESEMBLANCE IN ANIMALS.

To increase the resemblance, these insects when at rest
have the habit of placing their legs unsymmetrically. On

ell

Fie. 56.—The Leaf-Butterfly. (After Wallace.)*

* The author is indebted to Messrs. Macmillan & Co. for this figure.

SEA-HORSES. 179

the other hand, the leaf-insects, or “walking leaves,” of
India, both in colour and form, so exactly simulate green
leaves that they may be passed dozens of times without
attracting attention. All the legs of these curious
creatures are furnished with irregular flat expansions
looking precisely like bitten leaves ; while the head and
fore part of the body forms a kind of stalk expanding
behind into a broad and flattened abdomen, covered by
the horny wings, which are veined and netted so as to
form an almost exact imitation of a leaf.

We might cite many other instances of inanimate
mimicry among insects, but we must pass on to show that
this phenomenon is by no means confined to this group of
animals. Perhaps we should scarcely expect to find this
kind of mimicry in such a comparatively highly organized
a creature asa fish; yet there is a group of fishes, familiar
to those who have kept aquaria, under the name of sea-
horses, in which it is exhibited in its full perfection. The
ordinary sea-horse attaches itself to a sea-weed or some
other object by curling its tail tightly round it; and all
these fishes have the habit of anchoring themselves by
their tails in some way or another. In all of them the
hard, horny body is furnished with a number of prominent
ridges and spines; but in one, belonging to a peculiar
group from the Australian seas, these spines attain an
enormous development, many of them being prolonged
into irregular filaments or streamers of skin, which are
especially developed throughout the long and slender tail.
As these streamers float in the water, they so exactly
resemble, both in colour and shape, the particular kind of
sea-weed to which these fishes are in the habit of attach-
ing themselves, that the whole creature seems but part and
parcel of the fucus ; so that when on the sea-bottom it
must be impossible for any carnivorous rover to distinguish
between the animal and the vegetable.

One more instance of this kind of mimicry, and we must
close this portion of our subject. This example is taken
from the mammalian, or highest class of animals, and,
although not such a perfect imitation of form as those we
have already mentioned, is very remarkable as occurring

n2

180 PROTECTIVE RESEMBLANCE IN ANIMALS.

so high up in the animal kingdom. Most of our readers
are probably acquainted, at least by name, with those
lowly South American mammals known as sloths. These
animals are inhabitants of the great forest regions of that
continent, and are of a sombre greyish colour, very like
that of the gnarled and lichen-clad boughs from beneath
which they are wont to hang back-downwards. Not only,
however, is their general colour like that of a lichen-
covered branch, but their coarse grey hairs actually develop
a growth of lichens upon themselves to complete the
resemblance to their surroundings. It is, indeed, clear
that the long grey coat of the sloths has been produced
for the sole purpose of this protective mimicry, for when
this is removed there is found beneath an under-coat of
softer fur marked by yellow and black stripes, which may
be pretty contidently regarded as the original coloration of
these animals.

We have now to consider animate, or true mimicry, in
which one animal imitates the form, and generally the
habits, of another in order to participate in the immunity
from foes enjoyed by the latter,owing either to the possession
of some formidable weapon, or to its unpalatable nature as
food. In all cases of this kind of mimicry it is essential
that the mimicked animal should be numerically far more
abundant than the mimicker, as otherwise predatory
creatures would soon learn that the innocuous and palatal
animal was as likely to be captured as the harmful
one. Undoubted cases of true mimicry are most common
among insects, and it is to these alone that our ob-
servations will be confined. We may also observe that
mimicking insects, as a rule, mimick other insects, although
it has been considered that some large caterpillars mimick
snakes, and certain moths certainly imitate birds.

We will first refer to some excellent and well-marked
instances of mimicry which occur among insects of our own
country. Most of us are probably familiar with those large
hairy brown flies which may be seen in autumn creeping in
a sleepy sort of manner about the windows of houses, and
are commonly known as drone flies, aud scientifically as
Eristalis. These insects, although true flies, with only a

FLIES. 181

single pair of wings, are so like bees (in which, it need
scarcely be said, there are two pairs of wings) that it is
very difficult to persuade some persons that they are not
really members of that group of insects. Their resemblance
to the latter is increased by their similar habits, more
especially their bee-like buzz; and there is no doubt
whatever but that they are mistaken by birds for bees,
and thereby enjoy an immunity not granted to ordinary
flies. An allied kind of fly (Volucella) goes even farther
than this,and actually deceives the humble-bees themselves,
which it closely resembles both in form and coloration.
The object of this mimicry is to enable these flies to pass
freely in and out of the nests of bumble-bees in order to
deposit their eggs, which eventually hatch into larve
whose food are the grubs of the bees. Again, the gaudy
flies marked with bold bands of black and yellow which
are so common on fine summer days in gardens, and are
known as wasp-flies (Syrphus), take their name frum their
resemblance to wasps, which in some species is so close as
to make it difficult to convince people that they are not
really wasps.

Less common than the above-mentioned flies are the
beautiful British insects known as clear-winged hawk-
moths. Some of these, named hornet clear- wings (Sphecia),
so exactly resemble large wasps or hornets that they would
deceive nine persons out of ten who are not entomologists.
Moreover, they have exactly the same habits as hornets,
and when caught will actually curl up their bodies in a
wasp-like manner as if about to sting, although they are
perfectly harmless. Less complete is the resemblance of
other clear-wings—hence known as_bee-clear-wings—to
humble-bees. These insects, as has been well observed,
are, however, very important, as proving that their mimicry
is an acquired character, since when they first emerge from
the chrysalis their wings are thinly covered with the well-
known minute scales characteristic of ordinary moths,
these scales soon falling off and leaving the wings per-
fectly transparent. This indicates that the ancestors of
the clear-wings had wings like other moths.

In all the foregoing instances the mimicking insects

182 PROTECTIVE RESEMBLANCE IN ANIMALS.

imitate various members of the Hymenopterous order ;
but we have now to notice a case where a moth imitates a
bird so completely as to deceive even the best observers
when the two creatures are on the wing together. The
moths in which this kind of mimicry occurs take their
name of humming-bird hawk-moths from this very cir-
cumstance, and are represented by a species not very
uncommon in some parts of our own country. So close
is the resemblance between these moths and humming-
birds that Mr. Bates tells us that, when on the Amazons,
he has actually shot specimens of the former in mistake
for the latter; and the natives of these regions are firmly
convinced that both are of the same species. The ex-
tended proboscis of the moth does duty for the slender
beak of the bird, while the end of the body of the former
is expanded into a kind of brush which imitates the tail
of the bird, Humming-birds are, of course, not seized as
prey by insectivorous birds, and hence the moths escape
their natural enemies from their resemblance to the
humming-birds. In our own country, where there are
no humming-birds, it is somewhat difficult to see what
advantage its bird-like form is to the humming-bird hawk-
moth, and possibly its comparative rarity may be due to
the absence of the birds it mimicks.

We come now to those very remarkable cases of
mimicry, as exemplified among the butterflies, where one
species imimicks one or even more members of the same
order, owing to the immunity of the latter from the
attacks of birds on account of their unpalatable taste.
That the mimicked butterflies are protected by their un-
pleasant taste has been amply proved by their being
offered over and over again to birds, by whom they are as
invariably rejected. Their immunity from attack is
further proved by their slow flight, and by the bright
colouring of the under sides of their wings, so that they
have no means of concealing themselves. Most of these
mimicked butterflies are found in tropical and subtropical
regions, and belong to the great families known as
Danide and Heliconiide. In America these butterflies
are usually mimicked by various species of the family of

BUTTERFLIES AND ANTS. 183

“ whites” (Picride), which, as we all know in the case of
our common cabbage-butterfly, are eagerly sought by
birds; and the difference of the mimicking species from
an ordinary “white” by the assumption of the bright
colours of the Danaids is so great that nobody but an
entomologist would imagine for a moment that it even
belonged to the same family. Itis, moreover, curious that
there is one instance where two species of Heliconids
inhabiting adjacent regions are respectively mimicked by
two varieties of one and the same species of “‘ white.”

Stranger even than this is, however, the case of certain
South African swallow-tailed butterflies. In this group,
as a rule, both sexes are alike, and furnished with the
characteristic “tails”; but in one South African species
the females entirely lose these appendages, and alter their
coloration and the form of their wings so as to mimick not
only one, but actually three distinct species of Danaids.
Here, then, we have an instance in which a single species
of butterfly exists under four totally distinct forms ; viz.,
the typical swallow-tailed male, and the three varieties
of tailless females respectively mimicking the three Danaids.
No one would have the faintest idea that the three females
belonged to the same family, let alone to the same genus
and species, as the male; while the three varieties of the
female would be assigned without hesitation to as many
distinct species. That female butterflies are more often
protected by mimicry than the males is a fact which may
probably be explained by their extreme importance to the
race, and also from the circumstance that when heavily
laden with eggs they are more likely to fall a prey to birds
than are the lighter males.

A great deal more might be said on the subject of
mimicry in butterflies, but we must pass on to our last
instance of this feature, which is, perhaps, the most
peculiar of all. In this case the mimicked insect belongs
to that peculiar group of ants which have the curious
habit of carrying in their mouth a leaf which extends
backwards over their bodies, and apparently acts as a kind
of shade. Now, in British Guiana, there is an insect
allied to the cicadas and other bugs, in which the leaf

184 PROTECTIVE RESEMBLANCE IN ANIMALS.

borne by these ants is represented by the thin and laterally
flattened body of the creature, which is so compressed that
it does not exceed a leaf in thickness, while its jagged
upper border simulates well enough the irregular contour
of the leaf carried by the ants, of which the borders are
generally gnawed by the bearers. Although the legs and
lower part of the body of this most curious insect are
reddish in colour, the leaf-like upper part of the body has
assumed a green hue exactly resembling that of the ant-
borne leaves. Ina drove of cooshie ants, us the leaf-bearers
are called, the mimicking insect is distinguishable solely by
its somewhat inferior size; this difference is not, however,
sufficiently great to attract the attention of birds, which
have learnt by experience that the cooshies are by no
means palatable morsels.

It would be beyond the scope of the present chapter to
enter upon the difficult question of the means whereby
these mimetic resemblances, whether to animate or
inanimate objects, have been produced ; but sufficient has
been said to show that an amount of interest lies in the
subject, and those whose interest has thus been aroused
may perhaps have the good fortune to discover new and
unsuspected instances of one or other of these types of
protective resemblances.

SEA-URCHINS. 185

CHAPTER XVIII.
SEA-URCHINS.

PrRoBaBLy most visitors to the seaside are mere or less
familiar with the shells of those marine creatures commonly
known as sea-urchins, or sea-eggs, this acquaintance being
usually due either to finding “them cast up on sandy
beaches, or to seeing them offered for sale by the vendors
of curiosities and natural history objects. In many
instances it is probable that the acquaintance ends here,
although in others these objects may have been submitted
to a fuller examination ; but, in any case, we venture to
say it is comparatively few who have studied them with
the care and attention that their beauty of form and pecu-
liar structure demands, and still fewer who know anything
about their history in past times. Those, however, who
care to take up the subject will find it one of more than
usual interest, and we accordingly propose in this chapter
to place before the reader some of the leading features
and peculiarities of these creatures, which will form
stepping-stones for those inclined to proceed further with
their study.

To begin with, sea-urchins take their name from the
array of movable spines with which the shell is covered
during life, and which suggest comparison with those of
the true urchin, or hedgehog. The shell, as it is commonly
called, will, indeed, be the portion of the animal to which
alone our attention will be directed, since it is only this
part that is capable of preservation in a fossil state. We
must, however, state at the outset that, as this so-called
shell does not by any means correspond in structure with
the shell of a mollusc, it is found more convenient to give
it a different name, and the term test has accordingly
been selected. Moreover, since the name sea-urchin is a
somewhat long one, we may conveniently abbreviate it to
urchin, unless we prefer to use the more technical term
Echinoid.

There is great variety in the form of the hard calcareous

186 SEA-URCHINS.

test of the urchins, which varies from a shape somewhat
resembling a flattened orange to a heart-shape, or even to
a thin disc-like plate. ‘The ordinary urchins shaped
somewhat like an orange are, however, those best adapted
for gaining a general idea of the structure of the group,
and we shall accordingly commence with them. :
If, then, we examine such a test, we shall find that it
has an aperture at each of the two poles; while it is
divided into a series of meridional areas, each composed
of a number of separate oblong calcareous plates, fitting
accurately with one another at their edges, where they are
united by a thin membrane. The upper surface of such a
test is shown in Fig. 57, from which it will be seen that
the upper or apical
va pole, as it may be con-
veniently called, con-
sists of five somewhat
heart - shaped plates
surrounding a small
circular orifice which
is closed with mem-
brane in the living
state. This central
orifice is the vent,
while the five plates
forming a star sur-
rounding it, which
generally fall out in
the dry state, consti-
Fie. 57.—Upper Surface of the Test tute the aprcal dise.
of the Common Sea-Urchin. a, ambu- At the opposite or
lacral areas; 7 a, intermediate areas. lower pole, we shall
find a much larger
aperture, which forms the creature’s mouth; and we may
observe that just inside this aperture of the test in the com-
plete animal there will be found a very complicated cal-
careous masticating apparatus known as Aristotle's lantern.
Putting aside for the present the apical disc, we may
devote somewhat fuller attention to the main body of
the test, technically termed the corona. As we have said,

ae,

STRUCTURE OF TEST. 187

this consists of a series of meridional areas composed ot
numerous small plates ; and we shall find that these areas
form ten alternating series, each of which consists of two
meridional rows of the aforesaid plates. The line of
division between the two rows in each area is well marked,
although the divisions between any two areas are much less
distinct. It will further be seen that, while in one series
of areas (7 a) the plates are much wider than in the other
series (a), they are also somewhat deeper. Now, if we
were to look from the inside of the test towards the light,
we should find that the outer half of each plate in the
narrower areas has several minute perforations ; and it is
through these minute perforations that, during life, the
animal protrudes the curious tube-like feet, by the sucker-
like action of which an urchin is enabled to climb up the
glass wall of an aquarium. Since these narrower areas are
connected with the function of progression, they are
appropriately termed the ambulacral areas, and the larger
intervening spaces are accordingly called the intermediate
areas. It is almost superfluous to add that the whole test
of an urchin thus consists of five ambulacral and five
intermediate areas, which between them comprise twenty
separate rows of plates, each running continuously from
one polar aperture to the other. During life, each plate is
separated from its neighbour by a thin membrane, and
the test increases in size both by additions to the edge of
each plate and also by the interpolation of fresh equatorial
zones of plates between the upper edge of the corona and
the apical disc. The spines of the urchins are movably
attached to the knobs with which the test is covered, and
vary mucb in form and size, although the limits of this
chapter do not admit of further reference to them.
Reverting to Fig. 57, we may also see that the ambulacral
areas of the common urchin form a five-rayed star, on the
test of which, in the position of the figure, three rays are
turned away from the spectator and two towards him.
Now this radiate arrangement at once forcibly reminds us
of a star. fish, and any person who has ever handled those
creatures when alive will be aware that from their under
surface they can protrude tube-like sucking feet, precisely

188 SEA-URCHINS.

similar to those we have referred to as existing in the
urchins. Both these points of resemblance are, indeed,
indicative of an intimate relationship between urchins and
star-tish. And, as a matter of fact, the ambulacral areas
of the one represent the five rays of the other; the iter-
mediate areas of the urchins being an addition to the
structure of the star-fish. At first sight it looks, indeed,
as if these animals were really symmetrically radiate, but
we shall show later on that this is not the case, and that
they are, in truth, bilaterally symmetrical like the higher
animals, although this bilateral symmetry has been more
or less thoroughly masked by the radiate arrangement of
the parts.

Urchins and star-fishes are, however, not the only
members of the group of Echinoderms; since this also
comprises the beautiful stone-lilies or crinoids,* the joints
of the stems of which form the well-known “ St. Cuthbert’s
beads,” of the Whitby lias, while the so-called entrochal
marble, so often employed for chimney-pieces and other
decorative architecture, is almost entirely composed of
these stems. There are, moreover, certain entirely extinct
types, such as the Cystoids and Blastoids, of which more
anon.

Before proceeding to trace the modifications which the
test of the urchins undergoes in different members of the
group, it may be observed that in all urchins, whether
recent or fossil, the number of meridional areas is in-
variably ten; while in every existing kind of urchin, no
matter what be its size or shape, the number of rows of
plates composing such areas never departs from twenty.
As soon, however, as we reach the strata lying below the
chalk and gault, known as the lower greensand, which
constitute the lower part of the Cretaceous system, we find
an urchin which departs scmewhat in the last-named
respect from the existing type. A side view of the test of
this species is given in Fig. 58, from which it will be seen
that while at the apical pole the number of meridional
rows of plates is the normal twenty, as we approach the

* See page 157.

EXTINCT TYPES. 189

equator the series of meridional rows in each intermediate
area is increased to four, which continue to the basal pole.
Going still further back to the trias, we find another
genus of urchins (Tiarechinus) with an increase in the
number of rows of plates in the intermediate areas above
the lower pole. Moreover, some of the urchins of the
Jurassic rocks differ from the ordinary type, in that the
plates of the test overlap one another instead of joining by
their edges.

These depar-
tures from the
normal form in
some of the
Secondary ur-
chins suggest
that, if we were
to go back to the
Paleozoic epoch,
we should find
still more marked
differences from
living types. Fig. 58.—Side view of the ‘Test of a
Such, indeed, is Secondary Sea-Urchin (Zetracidaris).
actually the case, % ambulacral areas; 1a, intermediate areas.
and we find that all the Paleozoic urchins differ from
existing ones in the number of meridional rows of
plates, while very frequently these plates overlap one
another. In the specimen represented in Fig. 59 it will be
seen that while the ambulacral areas are normal, the
intermediate areas have now no less than five meridional
rows of plates; while in yet another form (JZelonites) the
ambulacral as well as the intermediate rows are increased
in number, the former varying from seven to eight, and
the latter from eight to fourteen. With one exception,
however, all the Paleozoic urchins agree with the common
species in having the vent situated at the apical, and the
mouth at the basal pole, this mouth always having the
“ Aristotle’s lantern.”

Now if we proceed still further back till we reach the
lower part of the Paleozoic epoch, such as the Cambrian

190 SEA-URCHINS.

and lower Silurian, we shall find a totally extinct group
of Echinoderms known as Cystoids. The hard parts of
these creatures consist of a nearly globular test, usually
supported on a short stalk, and composed of a number of
polygonal plates, having no definite meridional arrange-
ment, but traversed by five, or fewer, irregular ambulacral
grooves radiating from the mouth. Andit will be obvious
that, in their large number of meridional rows of plates,
the Paleozoic urchins present a mucb closer resemblance
to these extinct Cystoids than is offered by their existing
representatives. Indeed, if we be-
lieve in the derivation of one form of
animal from another, it seems pretty
evident that starting from the Cystoids
—the oldest known Echinoderms— we
can pass readily into the Paleozoic
urchins, from which we are conducted
by the above-mentioned intermediate
Secondary forms to species of the type
of the common urchin of the present
day. What particular advantage the
modern urchins have gained by the
reduction of their meridional rows to
twenty is, however, not very easy to

Fie. 59.—Side view determine; although this reduction
of the Test of = has probably conduced to greater
eee u sca compactness and strength in the
ambulacral areas; ia, Structure of their test, which may
intermediate areas. alone have been a sufficient improve-

ment on the older types.

The transition from the Paleozoic to the modern forms
does not, however, by any means exhaust the modifica-
tions which the urchins have undergone with the march
of time. Reverting once more to the common urchin
(Fig. 57), it should be mentioned that this type, in which
the test is radiately symmetrical and the vent and mouth
are polar, constitutes the group of the so-called regular
urchins. Although this type is still well represented, yet
a large number of the urchins of the Secondary, Tertiary,
and recent periods have departed very considerably from

2.

HEART-SHAPED URCHINS. 191

this simple form, to assume a more or less decided heart-
shape, with one or both apertures of the test becoming
eccentric, and with a frequent tendency for the perforated
portions of the ambulacral areas to become restricted to
the central part of the upper surface, where they form
a flower-like pattern (Fig. 60). Such types constitute
the group of irregular urchins, which, on the doctrine of
evolution, may be safely regarded as derived from the
regular group. Moreover, not satisfied with the assump-
tion of these new shapes, the irregular urchins appear to
have considered the ‘“ Aristotle’s lantern,’ which had
served their ancestors as a masticatmg organ for countless
ages, only a useless in-
cumbrance, and, accord-
ingly, the more advanced
“radicals’?’ among them
have totally discarded this
piece of apparatus, and,
indeed, appear to get on
equally well without it.
The forms connecting
the more aberrant mem-
bers of the irregular with
the regular group of
urchins are both numerous
and varied. Among them
we may refer to the com-
mon little helmet urchin
(Echinoconus) of our Fria. 60.—Upper surface of the Test
chalk. The test of this of a Cretaceous Heart - Urchin
species is about an inch coals Min, Valor areas ;
an height, and foring-Actall 7 a, intermediate areas.
cone, which is not quite radiately symmetrical. The
mouth, indeed, retains its usual position at the basal
pole, while the perforated areas extend from pole to pole.
In place, however, of the vent being situated in the centre
of the apical disc, it has been transferred to the margin of
the lower surface, in the middle of one of the intermediate
areas. It is thus placed opposite to an ambulacral area
corresponding to the one directed upwards in Fig. 57;

192 SEA-URCHINS.

and we thus, for the first time, find a regular bilateral
symmetry fully established. In the particular species to
which we have referred (as in all the under-mentioned
forms), the “ Aristotle’s lantern” has been lost, although
it is retained in other members of the same group. One
specimen of a helmet urchin has been discovered showing
the rare abnormality of having but four ambulacral areas.

A further step is shown by the so-called sugar-loaf
urchin (Ananchytes) of the English chalk, the tall silicified
tests of which are so commonly found in the gravel derived
from the denudation of the chalk. Jn this species, which
is considerably larger and more ovoid than the helmet
urchin, the elevated form of the test is still retained, but
the contour of its under surface has become more decidedly
heart-shaped. Moreover, the vent has become shifted
completely on to the lower surface; while the mouth,
although remaining (as is invariably the case) on the
under surface, has travelled away from its original central
pusition so as to be placed in the ambulacral area corre-
sponding to the one directed upwards in Fig. 57. Here,
therefore, we have the bilateral symmetry still more
distinctly marked. Another advance shown in this urchin
is the circumstance that the perforated portions of the
ambulacral areas, instead of extending on to the lower
surface of the test, stop short at the edge. Some members
of the same famiuy are still more peculiar in that the apical
disc is greatly elongated from front to back, in consequence
of which the five ambulacral areas do not all meet one
another at the summit of the test: those corresponding to
the three turned away from the spectator in Fig. 57
meeting near the middle of the test ; while the remaining
two are brought together in the opposite part of the test
corresponding to the lower portion of the same figure.

A third common chalk species, the heart-urchin, or
fairy heart of the quarrymen (Micruster), affords a good
example of what may be regarded as the extreme modifi-
cation of structure developed in the group. The upper
surface of one of these urchins is represented in Fig. 60,
from which it will be seen that the contour is regularly
heart-shaped, and the whole test much depressed. The

HEART-URCHINS. 193

perforated portions of the ambulacral areas are now
restricted merely to the central region of the upper
surface, one of these areas (directed upwards in the figure)
forming a shallower groove, and being otherwise markedly
different from all the others. In such an urchin the
bilateral symmetry is very strongly marked indeed, and,
since the upper border of the figure represents the
anterior, and the lower the posterior extremity of the
animal, we may compare the three anterior ambulacral
areas to the head and arms of a quadruped whose hind
legs will be represented by the two posterior ambulacra.
In regard to the position of the two orifices of the test in
this species, the vent is situated on the flattened posterior
surface, near its junction with the upper surface, while the
mouth occupies a position nearly midway between the
centre and the anterior border of the lower surface, at the
commencement of the groove formed by the anterior
ambulacral area. The mouth is peculiar in that it does
not open directly on the surface, in the usual manner, but
has a projecting lip by means of which its aperture
assumes a forward direction. The common purple heart-
urchin (Spatangus) of our present seas is a larger
representative of this group, presenting the same general
type of structure.

We thus see how gradual is the passage from a species
of the type of the common urchin to that of the heart-
urchin, widely different as are these two from one another.
We might, indeed, proceed further with our investigations,
and show how certain of the irregular urchins have become
so flattened as to assume the form of thin plates, which
in some instances are deeply notched at their periphery.
And we might also investigate the variation of form and
size displayed by the spines of the different groups.
Enough has, however, been written for our present object,
which has been to show the amount of interest that
attaches to the investigation of the lines of modification
on which development has proceeded among the sea-urchins.
This has shown how a regular progressive advance in one
particular direction has taken place from the earlier to the
later members of the group; and we thus have another

oO

194. SEA-URCHINS.

excellent instance testifying in favour of the doctrine of
evolution. This brief sketch may possibly give additional
pleasure to a sea-side sojourn, by inducing some of our
readers to direct their attention, first of all, to the recent
sea-urchins, after which they will scarcely fail to extend
their investigations to the fossil species so abundantly
distributed through our rocks ; and, we will venture to add,
that if they do so their interest cannot fail to be aroused.

NUMMULITES AND MOUNTAINS. 195

CHAPTER XIX.

NUMMULITES AND MOUNTAINS.

Botu the proverb “as old as the hills,’ and the
phrase the “everlasting hills,” are but the expression of
the natural tendency of the human mind to regard all
hills and mountains as the most lasting and ancient
objects with which we are familiar. As, however, is so
often the case, science steps in and tells us that, although
the proverb and the phrase are true enough as regards
human experience, yet that when we go back and study
the origin of things, as revealed by geology, we find that
many hills and mountains—and more especially the
highest of them—are actually among the very newest
features ma the physiognomy of the earth, and that the
expression ‘“‘as old as the plains” would, in many instances,
be a far truer simile than the one current.

If, indeed, we reflect for a moment, we shall be con-
vinced that the Tere mountains of the globe—always
excepting voleanoes, which have the power of renewing
their height—must necessarily, as a general rule, be
younger than many of those of lower height, or even than
the plains from which they rise. Thus rain, snow, frost,
and rivers are perpetually tending to wear down and wash
away all the higher points of the earth’s surface, and to
carry the débris to the valleys below. Consequently, we
are led to conclude that, prin? facie, the higher a moun-
tain range is, the less time it has been subject to this
washing-away process, and, therefore, the younger it is as
regards relative age. It might, indeed, be objected to this
that the mountains that are now the highest have always
been the highest; and that at the beginning of all things
their original height as much exceeded their present
height as the latter does that of the smaller ranges. In
this view, however, their original heights would have had
to be so stupendous as to be almost inconceivable, and

0 2

196 NUMMULITES AND MOUNTAINS.

probably much greater than is compatible with the physical
conditions of the globe. This hypothesis may, therefore,
be dismissed as untenable; more especially as there is
direct evidence of a totally different kind, which is
conclusive as to the truth of the alternative view.

This evidence is afforded by fossils, and more especially
by a particular kind of fossil, which, from its abundance
and the restricted geological epoch in which it is found in
any quantities, is of more than usual value in inquiries
of the present nature.

If any of our readers have ever examined the Tertiary
clays and sands of Barton, in Hampshire, or of Brackle-
sham, on the Sussex coast, they will probably have met
with numerous disc-like objects, the larger of which are
somewhat more than an inch in diameter, while the
smallest are scarcely bigger than a pin’s head. When
split or cut, these objects are found to contain a number
of minute chambers, separated from one another by thin
walls arranged in the form of a spiral, as shown in the
figure. Technically they are known as nummulites, and
belong to the very lowest division of the animal kingdom—
lower even than the sponges, which some people cannot
be persuaded to believe are animals at all. Now these
nummulites are exceedingly interesting to those who study
the growth and formation of mountain ranges for the
reason that they occur, in any quantity and of large size,
only through the greater portion of the Eocene or lowest
division of the Tertiary (latest) geological period, although
not reaching down to the London clay ; and also because
they were very widely distributed in the seas which then
covered a large part of our existing continents. If, then,
we should find rocks containing great numbers of large
numinulites on the flanks or tops of a mountain range, we
should be assured that such range was younger than the
Eocene period, at which date its component rocks were
being formed as mud at the bottom of the sea.

Now, although in England the aforesaid nummulites
only oceur in soft beds of clay and sand in the low cliffs
of the southern coast, when we cross to the Continent we
find them forming the greater part of a massive limestone,

NUMMULITIC LIMESTONE. 197

known as the nummulitic limestone. This very charac-
teristic rock is more massive and more widely spread
than any other Tertiary deposit, and, in its thickness and

Fie. 61.—A Numiulite, viewed from above, and horizontally bisected.

identity of structure over large areas, recails the mountain
limestone of the Paleozoic epoch. It is, indeed, abso-
lutely one mass of nummulites, of which sections are
displayed on every fractured surface ; and it was probably
an open sea deposit, which must have taken incalculable
ages for its formation. It occurs in southern Europe in
both the Alps and Pyrenees, attaining a thickness of
several thousand feet in the former, and occurring at
elevations of more than 10,000 feet above the sea-level.
In the Pyrenees it forms a beautiful white crystalline
marble. On the south of the Mediterranean, nummulitic
limestone is found again in the mountains of Algeria
and Morocco. In eastern Europe it reappears in the
Carpathians, and thence may be traced into the Caucasus
and Asia Minor. All travellers to India are familiar with
the Mokattam range of bare mountains on the western
shore of the upper part of the Red Sea, which are likewise
almost entirely composed of this same limestone. It is,
indeed, a common belief among the Egyptian peasantry
that the larger disc-like nummulites are lentils left by the
builders of the pyramids, and subsequently turned into
stone. From the Caucasus and Asia Minor the nnummu-
litic limestone may be followed into Persia, Baluchistan,
Sind, the Punjab, and so into the Himalaya. Thence

198 NUMMULITES AND MOUNTAINS.

it continues into Assam and Burma, and reappears in the
Andaman and Nicobar Islands in the Bay of Bengal.

It is, however, in the inner Himalaya that the occur-
rence of nummulitic limestones and certain overlying
Tertiary rocks is of more especial interest, since it is there
that they attain a greater elevation than in any other part
of the world. It is in the upper Indus Valley, in the neigh-
bourhood of Leh in western Tibet, that these nummulitic
rocks occur; running some distance down the Indus to the
west of Leh, and to the eastward of that town extending
into Chinese territory. There is good evidence to show
that the arm of the sea in which these nummulitic rocks
were deposited communicated with the ocean to the east-
ward in the Bay of Bengal, instead of following the course
of the Indus in a westerly direction to the Arabian Sea.
Moreover, in some parts of this area the rocks which
overlie, and are, therefore, newer than the nummulitic
limestone, are raised to the stupendous elevation of more
than 21,000 feet above the sea-level.

We have, therefore, before us decisive evidence to show
that those parts of the earth’s surface which at the present
day form some of the highest peaks in the Himalaya were,
at the period when the London clay was deposited, below
the level of the sea; and consequently that the elevation
of that part of the Himalaya has taken place entirely
since that epoch, during a period when the physical
features of England have altered only to a comparatively
slight degree. There is, moreover, equally conclusive
evidence to show that the elevation of the Himalaya was
not completed until a much later epoch of the earth’s
history, since on the southern flanks of this mighty range
we find beds of sandstone containing remains of mammals
which lived during the Pliocene, or later Tertiary epoch,
raised to a height of several thousand feet above the sea-
level.

The elevation of the Indus Valley in the heart of the
Himalaya could not, therefore, have commenced until the
Miocene, or middle Tertiary epoch, while that of the outer
Himalayan ranges could not have been completed till far
into the Pliocene period, and, for all we know to the

DATES OF ELEVATION. 199

contrary, may still be in progress. Not only so, but the
same evidence likewise tells that the Alps, Pyrenees,
Carpathians, the Caucasus, and the Egyptian Mokattam
range, as well as the mountains of Algeria, have all
attaimed their present elevation since the latter part of the
Eocene period, when at least a considerable portion of
their area was submerged. And we accordingly learn that
many of the most striking physical features of the Old
World are of comparatively modern origin.

When, however, we turn to mountains like those of the
Lake District and Wales, which only attain moderate
elevations, and in which the rocks belong solely to the
Paleozoic, or oldest geological epoch, it is evident that we
have to do with elevations of an extremely remote date.
There is, indeed, satisfactory proof that these old moun-
tains were once vastly higher than they are at present;
their diminished altitude being due to the long ages during
which they have been subjected to the wear and tear of
the elements. To such mountains the proverb to which
we have already alluded is, therefore, strictly applicable ;
but in a geological sense the phrase “ everlasting hills”
can be applied neither to the oldest nor the youngest
mountains.

200 A LUMP OF CHALK AND ITS LESSONS.

CHAPTER XxX.
A LUMP OF CHALK AND ITS LESSONS.

Prosasty all Englishmen—certainly all those dwelling
in the eastern and south-eastern counties—are familiar
with the pure white rock which we call, from the Latin
creta, chalk. It is indeed this very familiarity which
breeds the proverbial contempt, and causes us to take but
scant or little notice of what is really a very beautiful
substance in itself, altogether apart from the interest
with which it is invested from a geological point of view.
If chalk were very rare instead of being exceedingly
abundant, there is httle doubt that it would be reckoned
as a beautiful substance, worthy to stand as the best
example of a pure white mineral alongside of virgin
sulphur as the finest example of a yellow one. If, more-
over, chalk had happened to have undergone the action of
intense heat under equally intense pressure, it would
assuredly have produced an even finer and purer statuary
marble than that of Carrara, and might thus have been
one of the most valuable of rocks.

A complaint may not untrequently be heard among those
more or less deeply interested in geological science who
happen to dwell ina chalk country, that the very sameness
of the chalk formation throughout England prevents them
from finding any interest in the geology of their own
districts, and thus leads them to reeret that their lot had
not been cast in regions where a variety of rocks are to be
met with. Although there is a considerable amount of
truth in this complaint, yet if rightly studied the chalk is
so peculiar and unique aformation as rather to embarrass
us with the number of considerations and problems to
which it gives rise, than to be deficient in interest.

Examining a lump of the pure white chalk of many
parts of England, such us that of Dover, we find that it
consists, both under the naked eye and an ordinary lens,

NATURE OF CHALK. 201

of an exceedingly fine-grained homogeneous soft substance,
adhering strongly when applied to the tongue, and leaving
a white streak when rubbed on other substances. If
treated with vinegar, or any other acid, it will effervesce
strongly with the liberation of the gas commonly known
as choke-damp, or carbonic acid, while the base umtes with
the uew acid to form a fresh compound of lime. The
lime may be obtained in a pure condition by burning the
chalk, as in a lime-kiln, when the carbonic acid is likewise
given off; and we thus learn that chalk consists of
carbonate of lime. As arule, when we examine a chalk-
cliff we shall find that the chalk, although stained here
and there with iron, is identical in structure throughout
great thicknesses, and that it shows nowhere any signs of
crystallization. Occasionally, however, as at Corfe Castle,
near Swanage, in Dorsetshire, we shall find that the chalk
has become so hard as to leave no distinct streak when
rubbed lightly on other substances ; while its cracks and
fissures are filled with translucent crystals of white spar—
the cale-spar, or calcite of mineralogists. Here, then, we
have the chalk so hardened, probably by the effects of
subterranean heat, as to form what is pepularly called a
limestone ; while a farther step would have converted it
into actual marble. The geologist would indeed apply
the name limestone to chalk, ordinary limestone, and
marble indifferently; but since the popular usage is
different, it is well to be assured that all three are but
various modifications of one and the same substance. In
the north of Ireland the basalt of the Giant’s Causeway
has converted the chalk still more completely into a hard
limestone.

Chalk, then, may be defined as a fine-grained, white,
non-crystalline, soft limestone. This, however, by no
means exhausts the subject of its composition. Thus
if we take a piece of chalk and wash it carefully in water
with a hard brush so as to reduce it to a state of mud,
and examine the portion which falls to the bottom of the
vessel under a microscope, we shall find that this is very
largely made up of various shell-like substances. Many
of these are minute fragments of what may have been real

202 A LUMP OF CHALK AND ITS LESSONS.

shells, while others are portions of the spines of sea-
urchins, and others, again, are the flinty spicules of
sponges. By far the larger proportion consists, however,
of perfect objects of extremely minute size, mainly be-
longing to that lovely group of animals known as
foraminifera, or shortly, ‘“‘forams.” Of these beautiful
little shells some are coiled in a manner recalling the shell
of the nautilus, while others consist of globular masses
arranged either in a coil or in a straight line, the globules
gradually increasing in size from the summit to the mouth
of the shell. In all cases, however, the walls of these
shells are perforated by the inconceivably minute apertures
from which the forams take their name, and through
which, when alive, the creatures protruded delicate threads
of the jelly-like protoplasm of which their soft parts are
composed. Truly marvellous in beauty are these forams,
although pages of description can give but a faint idea of
them, and the student should see them for himself under a
microscope. So numerous, however, are these forams,
and other equally minute organisms in the white chalk,
that they frequently compose half its substance, while it is
stated that in some rare cases they may even rise to as
much as ninety per cent.

We have now, therefore, to add to our definition of chalk
that it is largely composed of the shells of the minute
animals known as forams, together with those of other
allied creatures, and so many accordingly speak of it as a
limestone which is evidently, to a large extent, of organic
origin. Moreover, as these forams are more or less closely
allied to species inhabiting the ocean at the present day,
we should be justified from this evidence alone in regard-
ing the chalk as a formation of marine origin. This origin
is, however, equally well proved by the larger fossils, such
as the shells of sea-urchins, scallops, oysters, &c., commonly
occurring in the chalk; while, in addition to this, the
extreme purity and thickness of the formation would of
itself be sufficient to demonstrate that the chalk is the
result of long-continued deposition on the bottom of the
sea.

Thus much for the composition of our lump of chalk as

THE CHALK FORMATION. 203

examined in the laboratory, and we now turn, as all
geologists worthy of the name should, to its occurrence
in the field. If we look at one of the tall chalk cliffs of
our southern coasts, as in the neighbourhood of Dover, we
shall be first of all struck with the extreme homogeneity
and purity of the whole formation from top to bottom,
through a thickness which in this neighbourhood is close
upon 1000 feet, and in Norfolk is more than 1100 feet.
This similarity of composition throughout such a vast
thickness is totally unlike what we are accustomed to
observe in other rock-cliffs (although there is some
approach to it in the blue mountain limestone of Derby-
shire), where we generally find alternating bands composed
of rocks differing both im colour and structure from one
another, and we are thereby led at once to conclude that
there must be something very peculiar connected with the
deposition of the chalk. How was it that in the old sea
there were not only no currents bringing loads of sand or
clay to alternate with the pure white limestone, but, above
all, that there was not a tinge of colouring matter to stain
the virgin purity of the newly-forming chalk during those
ages and ages of time, while drifted logs and fruits occur
but rarely ?

A closer inspection of a large thickness of chalk will,
however, reveal the fact that there is not a complete
similarity in the nature of the rock throughout the entire
formation. Thus, whereas in places where nearly the
whole formation is displayed we find throughout the
uppermost 400 feet layers and nodules of flint are thickly
distributed throughout the mass, generally forming more
or less well-marked lines which indicate the original
planes of the deposition of the rock, as we pass to a lower
level the proportion of these flints becomes gradually less,
till, after we have passed downwards through some 130
feet, they finally disappear, and are wanting throughout
the whole of the lower part of the series. Moreover, in
this lower chalk, or chalk without flints, we shall find, as
we pass downwards, a gradual tendency to lose the pure
white colour of the upper chalk, and to assume a buff or
greyish tint, while in the very lowest beds we shall not fail

204 A LUMP OF CHALK AND ITS LESSONS.

to notice the appearance of a number of small grains of a
ereenish-coloured mineral. If, again, we try to dissolve
this lower chalk in acid we shall find that as we descend
in the series there is an ever-increasing quantity of an
insoluble remnant, which would be shown by analysis to be
of the nature of clay. Both these circumstances poimt to
the conclusion that at the time the lower chalk was laid
down the conditions were by no means so well adapted for
the deposition of a pure carbonate of lime as was the case
in the later time of the upper chalk with flints. What
these conditions were we shall consider subsequently, but
we have now to direct our attention to the area over which
the white chalk extends.

In the north-west the fiurthest limits to which the white
chalk extended are found near Belfast, where, as we have
said, the rock has been converted into a hard limestone by
the action of heat. Although we do not again meet with
chalk till we reach the east and south of England, where
it forms large portions of our coast from Dorsetshire to
Yorkshire, yet it is probable that the chalk sea embraced
the foot of the Welsh mountains, which formed an
archipelago. From England the white chalk may be
traced without any alteration in its character through the
north of France, the south of Belgium, the eastern part of
the Netherlands, and thence through Westphalia, Hanover,
and Galicia, into Poland and Russia, where it reaches on
the one side to the foot of the Urals, and on the other to the
Crimea; moreover, to the northward it occupies a con-
siderable portion of Denmark and the southern extremity of
Sweden. Although the white chalk is now only distributed
over the surface of this region in larger or smaller patches,
being sometimes covered up by newer (Tertiary) deposits,
and in other places totally wanting, there is evidence that
it once extended continuously over the whole. Moreover,
the absence of any traces of the white chalk in the regions
to the west and north of those mentioned, indicates that
the present limits of the chalk in those directions mark
approximately the boundaries of this cretaceous sea, this
sea being probably cut off from free communication
with the Atlantic by a barrier connecting western France

EQUIVALENTS OF CHALK. 205

with Cornwall and Ireland, and by another joining
Scotland with Scandinavia.

The above area includes the whole of the white chalk ;
but when we trace this chalk southwards into Bohemia
and Saxony we find that it has undergone a very
remarkable change. Thus, although it contains the saine
fossils as to the northward, the rock itself, instead of being
the pure white limestone to which we have beenaccustomed,
consists of a series of massive sandstone about as unlike
chalk as anything well could be. It is probable, indeed,
that these cretaceous sandstones, as we may call them,
were formed in a gulf on the southern coast of the white
chalk sea, which was unfavourable to the deposition of
chalk itself; and as these sandstones were undoubtedly
deposited at the same time as the pure chalk, we thereby
learn the very important geological lesson that similarity
or dissimilarity in the mineralogical structure of a rock is
a matter of very minorimportindeed. We may illustrate
this by reference to architecture. Thus, a Gothic church
may be built either of sandstone, limestone, marble, or,
for the matter of that, brick ; but it will still be (exclusive
of course of our so-called modern Gothic) absolutely
characteristic of one particular period of European archi-
tecture. This Gothic style will be distinguished by certain
peculiarities in the structure of its arches and pillars, as
well as by the ornaments with which they are embellished.
Just so in geology we have a chalk or cretaceous style, in
which, although the rock itself may be either chalk or
sandstone, or limestone, or slate, yet its architectural
details—that is to say, its fossils—will be the same, not
only throughout Europe, but within certain limitations of
variation, over the whole world. This is one of the
important Jessons to be learnt by a comprehensive study of
our white chalk.

The second great lesson taught by the white chalk is,
however, of perhaps still more importance. We have seen
that the white chalk was deposited in a sea cut off from
free communication with the Atlantic to the west and
north ; and the range of the Ardennes which formed its
shore in the south-west, together with the evidence of the

206 A LUMP OF CHALK AND ITS LESSONS.

near neighbourhood of a coast afforded by the sandstones
of Saxony and Bohemia, indicates that this sea was a
mare clausum (in a geographical, not a political sense),
somewhat like the Mediterranean or the Black Sea. Now,
from the apparent similarity of chalk to the ooze forming
in the abyssal depths of the Atlantic and the other large
ocean basins, it was taught but a few years ago that the
chalk itself was deposited in an ocean of similar depth.
The mare clausum theory, however, is of itself a suffiaent
obstacle to the acceptance of such a view, since it is
impossible to conceive that a sea of such small dimensions
could ever have had depths at all approaching those of the
Atlantic. The Atlantic theory, if we may so call it, of the
chalk was, however, at once and for ever dissipated by
the researches carried on during the voyage of the
“Challenger.” Those researches showed that the so-
called abys ssal deposits, instead of being very like the chalk,
were really very different. Even the ooze has not the
purity of the chalk; while the large areas of red clays
covering the ocean-basins have no analogy i in the latter.
Moreover, it has been proved that the aby ssal deposits are
laid down at a rate of almost inconceivable slowness—so
slowly indeed that even meteoric dust forms an appreciable
portion of the red clays ; while the ear-bones of whales
and teeth of sharks that strew the ocean-floor have lain
there so long as to have become coated over with a thick
layer of mauganese precipitated from the water of the
ocean. On the other hand, the remains of fishes and
other delicate organisms which occur so beautifully pre-
served in the white chalk clearly indicate that its
deposition must have been comparatively rapid, and must
have taken place in a sea where there was abundance of
mineral matter either in suspension or solution, Again,
the fauna of the chalk, especially the sponges, is one
such as would be found in comparatively shallow seas,
and is quite unlike that of the Atlantic depths. In-
deed, it is quite probable that the chalk sea may not
have exceeded some one or two thousand feet in depth.
The great difficulty in regard to the chalk is, indeed, to
explain its purity, and the. very rare occurrence of dr ifted

PERMANENCY OF OCEAN-BASINS. 207

materials found imbedded in it. The mare elausum, with
no tides and perhaps but few large rivers flowing into it,
and its shores largely composed of hard crystalline rocks
like those of Scandinavia and the Ardennes, will, however,
to a certain extent remove this difficulty. Even then,
however, it is doubtful how sufficient material for the
formation of the chalk could have been obtained; and
accordingly one of our most eminent living geologists
suggests that, in addition to its partially organic origin,
chalk may have been largely formed by a chemical pre-
cipitate of carbonate of lime.

Be this as it may, the degradation of chalk from its
former position as a supposed typical abyssal deposit has
taught the great lesson that almost all the stratified rocks
with which we are acquainted were laid down in com-
paratively shallow water, and consequently has led to the
general acceptance of the grand doctrine of the permanence
of continents and ocean-basins. By this, of course, it is
not meant that the whole areas of several of our continents,
such as Hurope, have not been (as we know they have),
many times over, beneath the sea. Indeed, what we have
already said as to the extent of what we may call the
cretaceous Mediterranean, shows that at a comparatively
late period of geological history a large part of central
Europe was sea. Neither does this doctrine forbid such
changes in the present configuration of the earth as would
be implied by a land connection between Africa and
southern India. What, however, it does say, and that in
the most emphatic manner, is that where continents now
are there deposits have always been going on, and there
land, of larger or smaller extent and of ever varying
contour, has always been; while the great ocean-basins,
like those of the Atlantic and Pacific, have existed as such
since the globe emerged from its primeval chaos. This,
then, is the second great lesson taught by a lump of chalk!

We have, however, by no means yet exhausted the
interest connected with the subject of chalk. In the first
place, the gradually increasing marly character of the lower
chalk points to a condition when the sea was much less
deep than at the period of the white chalk. If, indeed,

208 A LUMP OF CHALK AND ITS LESSONS.

we go lower down in the rock series, we shall find the white
character of the chalk has completely disappeared when
we reach the underlying blue ‘‘gault” of Folkestone, which
implies the existence of currents or rivers largely charged
with mud. Still further back, we have the fresh-water clays
and sandstones of the Weald of Kent and Sussex ; and
we thus learn that at that period southern England was in
the condition of a large delta, after which there was a
eradual subsidence, culminating in the mare clausui of the
period of the white chalk. Then, again, we have seen
how the “ architectural style’ of a rock, as exemplified by
its fossils, is the one all-important point connected with
it; and the alteration of the English chalk into the
cretaceous sandstones of Saxony ought to have prepared
us for more extensive modifications of these rocks as we
proceed to regions still more remote from where they are
typically developed. If, then, we turn to a geological map
of Europe, we shall find a large area of its southern half
coloured in, as being formed of cretaceous rocks—that is,
rocks equivalent in point of age to the white chalk. -The
description, or still better, an actual examination of these
rocks will show, however, that they have but little in
common with the white cbalk. They consist, indeed, of
hard, compact, and often dark-coloured limestones, con-
taining many fossils identical with those of our own chalk,
together with certain others of different types; thus
showing that we have entered an area where the conditions
of lfe were somewhat different from those obtaining in
the mare clausun of the white chalk. From the centre
and south of France these cretaceous limestones may be
traced across the Pyrenees into Spain, and so into North
Africa, while eastwards they extend across the Alps into
Switzerland, Italy, Bulgaria, Roumania, and thence along
the Mediterranean basin into Asia. That these rocks
stretch far into the heart of Asia is now well known, and
since rocks of somewhat similar type containing well-
known European cretaceous fossils are found in the inner
Himalayas, it seems highly probable that this southern
cretaceous sea connected the Mediterranean with the Bay
of Bengal. Whereas similar cretaceous fossils occur on

SUMMARY, 209

the east coast of India, in the neighbourhood of Madras,
and since there are some very remarkable similarities
between the fresh-water rocks of the peninsula of India
and those of South Africa, while many animals are now
common to those two countries, there are very strong
reasons for considering that peninsular India (which was
then cut off from the rest of Asia by the cretaceous sea)
had a land connection with the Cape by way of Madagascar.
We know indeed that this southern cretaceous sea com-
municated freely with the Atlantic, by what is now Spain
and France, and we are thus led to conclude that there was
formerly a direct sea communication between the Atlantic
and the Bay of Bengal by way of central Asia. Europe
and Asia then formed a northern continent separated by
this cretaceous sea (of which the Mediterranean is the
shrunken remnant) from a southern continent, which
included both Africa and India proper. Such is the wide
interpretation given to the doctrine of the permanence of
continents and ocean-basins.

The study of the European chalk, besides the two great
lessons to which we have especially directed attention, has,
therefore, proved to us the former existence of two great
seas, in which the cretaceous rocks were deposited—the
northern one, being a mare clausum, cut off from the
Atlantic, in which was deposited the white chalk; while
the southern one, in which the hard, massive limestones of
southern Europe were laid down, proved the connecting link
between the Atlantic and the Indian Ocean, to which we
have already alluded. We might pursue our subject
further, and discuss the origin and nature of the flint en
pyrites which are of such common occurrence in the chalk,
or we might direct attention to the more valuable and much
rarer phosphates which are sometimes contained in it.
We might, again, discuss the peculiar characters of the
cretaceous fauna, and show how that of the closed northern
sea differed from that of the open southern ocean. We
might do all this, and more; but what has been written is
sufficient to show the amount of interest and the many
weighty probican nnected even with a “lump of chalk.”

P

210 A FLAKE OF FLINT AND ITS HISTORY.

CHAPTER XXI.
A FLAKE OF FLINT AND ITS HISTORY.

In the foregoing chapter it was stated that the upper
white chalk, so far as hand specimens are concerned, is a
nearly pure limestone. This, indeed, is a perfectly true
statement as regurds such hand specimens; but when we
consider the upper chalk as a whole, we must not omit to
regard the numerous bands and nodules of flint with
which it is interstratified as a very important constituent
of the whole rock. We say a constituent of the whole
rock advisedly, because although the flint is now separated
from the white limestone which we call chalk in the form
of nodules and bands, yet there is evidence that it was
originally disseminated throughout the entire mass, and
that the upper chalk then formed a slightly siliceous
limestone. Probably everybody is more or less familiar
with flint as it occurs in a chalk-pit, or in the form of
gravel derived from the disintegration of chalk strata,
but it may be taken for granted that comparatively few
have ever seriously considered how the solid masses of
flint have originated in the soft chalk limestone. As this
is a subject of considerable interest, and one which has
given rise to much discussion, we propose to devote the
greater part of the present chapter to its consideration,
while we shall add some observations on the history of
flints after they have been removed from their native
chalk.

We shall assume, in the first place, that all our readers
are aware that flint is one of the manifold forms assumed
by that abundant constituent of the earth’s crust technically
known as silica—-the oxide of the element silicon. When
crystallized, silica occurs in the form of rock-erystal, or
quartz ; but flint is one of the many non-crystalline, or
amorphous, developments of the mineral. It is generally
defined as a massive dark-coloured or black, semi-trans-
lucent, dull-looking variety of silica; which when pure

NATURE OF FLINT. 211

burns to an opaque white, and has what is termed a
conchoidal or shell-like fracture. The dark colour, it may
be added, is due to the presence of a small quantity of
organic matter, or carbon.

If we fracture a nodule of flint freshly taken from a
chalk-pit, we shall find that the thin edges of the sharp
flakes which are seen to be produced have a pale-brown
horn colour when viewed by transmitted light, and that
as the flake becomes thicker the colour gradually darkens

Fra. 62.—A Chipped Flint Implement, from Icklingham, half
natural size. (From Sir J. Evans’ “ Stone Implements.’’)

P2

212 A FLAKE OF FLINT AND ITS HISTORY.

till it assumes the blue-black tint characteristic of the
mass. If, however, our flake contains a portion of the
external coat of the nodule, we shall see that for about
a quarter of an inch in depth the outer layer is far less
compact than the rest of the flint, and is of an opaque
white colour. In other specimens, again, we shall observe
that the colour, instead of the usual deep blue-black, is
of a pale whitish-blue, frequently marked by more or less
distinct bands. Needless to say that on trying to scratch
our flint flake with a knife we shall signally fail, and if
any result happens it will be that a thin film from the
metal of the blade will be left on the stone at the poiny
of contact.

Our flake will likewise exhibit in great perfection the
characteristic conchoidal fracture of flint; that is to say,
its surfaces will be smooth and undulating, swelling here
into a prominent convexity, and falling there into a deeper
or shallower hollow. Frequently, moreover, there may be
observed a number of small parallel wavy ridges on the
fractured surface. If we submit the edges of the freshly-
broken flake to a series of taps from our hammer, we
shall find that a number of smaller flakes will be readily
chipped off, each leaving a separate conchoidally-fractured
surface on the original flake. It is this facility with
which flint can be chipped, coupled with its hardness and
the sharpness of its fractured edges, that induced our
paleolithie ancestors to adopt it as the material for their
various weapons and tools. The figure on the preceding
page of one of these implements exhibits in great perfec-
tion the characteristic conchoidal fracture of flint.*

The extreme development of this peculiar and charac-
teristic fracture is, however, exhibited when a large flat
surface of flint is struck at right angles by a round-ended
hammer. The hammer then comes in contact with a
minute portion of the surface of the flint, which mav be
represented by a small circle, and as the flint is elastic,
“this small circle,’ as Sir John Evans observes, “is

* We are indebted to Messrs. Longman and Green for this and
the following figure.

SPONGES IN FLINT. 213

driven slightly inwards into the body of the flint, and the
result is that a circular fissure is produced between that
part of the flint which is condensed for
the moment by the blow, and that part
which is left untouched. As each particle
in the small circle on which the hammer

Fra. 6 ; . impinges may be considered to rest on

1@. 63.—Arti- 3 mre
ficial Cone of Flint, ™ore than one other particle, it is evident
(From Sir J, that the circular fissure, as it descends
Evans.) into the body of the flint, will have a

tendency to enlarge in diameter, so that
the piece of flint it includes will be of conical form, the
small circle struck by the hammer forming the slightly
truncated apex.” A little practice will enable anyone to
make these flint cones with ease. The size of the cone,
and the degree of steepness of its sides, vary with the
nature of the flint, the weight and form of the hammer,
and the force of the blow.

When examined with a lens or microscope, chalk-flint
frequently exhibits a perfectly uniform structure through-
out, without the least trace of the presence of any organic
body. In other cases, however, traces of sponges, corals,
shells, echinoderms, diatoms, &c., are more or less apparent
in flint. Perhaps the most common of al! these organisms
are the mushroom-shaped sponges known as ventriculites ;
and if we examine a flint containing one of these sponges
we shall frequently observe that there is a complete
transition from portions of the perfectly preserved sponge
to homogeneous flint, without the least trace of organic
structure. In the case of echinoderms, we shall find that
while in some cases the whole interior of the shell (or, as
it is technically called, test) is filled with flint, the shell
itself retaining its original calcareous structure, in other
instances the original shell itself has been completely
removed and replaced by flint. In some cases the original
structure of the sheil has been preserved in the flint, but
more geuerally this has been completely lost, and the flint
is structureless.

This replacement of a calcareous by a siliceous structure
is an instance of pseudomorphism. Similar remarks will

214 A FLAKE OF FLINT AND ITS HISTORY.

apply to the shells of molluscs, and likewise to corals. Itis
important to mention that the sponges found in flint were
not originally of the horny nature of our bath-sponges, but
were themselves composed of minute spicules and fibres
of silica, like the so-called Venus’s flower-basket of our
modern seas.

With regard to the mode of occurrence of flint, we have
first to mention that it is by no means confined to the
chalk, but may occur in limestones of any age. In this
country it is, however, more abundant and purer in the
chalk than m any other formation, and may, indeed, be
considered characteristic of the upper part of that forma-
tion.* Flints are found in the chaJk either in the form of
nodules or in thin continuous lamine. The nodules are
generally of very irregular shape, and may vary in size
from a walnut to masses of a hundred-weight or so. As
a rule they occur in strings at comparatively regular
intervals in the chalk, generally conforming more or less
closely to the original planes of bedding, and the indi-
vidual nodules bemg sometimes at considerable distances
apart, but at others closer together and more or less
connected by long root-like pieces. On the other hand,
the laminated or tabular flint may cut the bedding-planes
of the chalk at any angle, and is often found in joints and
fissures, which may emerge at the surface. As a rule, this
tabular flit is devoid of organisms. Not unfrequently
flints may be found which near their surfaces gradually
become paler and paler in colour, and contain an increasing
amount of calcareous matter, till they pass imperceptibly
into hard siliceous chalk. Again, flints may be hollow,
and contaim in their cavities either corals or sponges, or
masses of that variety of silica known as chalcedony.
The latter, it may be mentioned, is a semi-transparent
waxy-looking stone, generally with a more or less decided
pinkish tinge, and forming mammillated or botryoidal
masses. The milky and reddish varieties of chalcedony con-

* It also occurs abundantly in the lower part of the Portland stone
series of the Isle of Portland, but is there generally less pure, and has
the conchoidal fracture less marked.

ORIGIN OF FLINT. 215

stitute carnelian, while when it is arranged in differently
coloured bands it forms agate. Occasionally small crystals
of quartz occur in the hollows of flint.

It has still to be mentioned that in some districts—and
more especially near Norwich—in addition to the hori-
zontal layers of nodular flints, there occur in the upper
chalk a number of huge cup-shaped masses of flint placed
one above another in vertical lines; these masses being
locally known as “potstones,” and presenting a remarkable
resemblance to certain giant sponges called Neptune’s
cups.

The proportion of the flint to the chalk in the upper
chalk of England varies, acording to Prof. Prestwich,
from four to six per cent. It is important to add that the
masses of nodular flint may not untrequently be found to
be traversed by fractures which have subsequently been
reunited ; thus showing either that the substance must at
the time have been in a semi-plastic condition and capable
of reunion, or that the fracture has been united by the
subsequent deposition of siliceous matter. It must also be
mentioned that, as a rule, the white coating is confined to
the outer surface of the nodules, and that we do not find
layers of pure flint overlain with white coats and then
again by other similar layers; thus indicating that the
formation of the white coat was the final act in the
development of flint.

With these observations on the structure and mode of
occurrence of flint, we are in a position to enter on the
more difficult subject of its origin. From the very first it
was recognized by all geologists that such a peculiarly
hard and homogeneous substance as flint, occurring im
irregular nodules among the pure white chalk, could not
have been deposited in its present condition directly from
the waters of the cretaceous sea ; and the problem there-
fore presented itself to account adequately for its mode of
formation. The problem soon resolved itself first of all
into two questions, namely, whether the silica was originally
part and parcel of the chalk as first deposited and that it
subsequently gained its present condition, or whether it
was added at certain intervals during the deposition of the

216 A FLAKE OF FLINT AND ITS HISTORY.

shalk from a totally different source, or was introduced
subsequently to the deposition of the whole.

I believe [ am right in saying that there is still a current
notion among many persons who are not scientific geologists
that flint is a kind of igneous rock ; and its hardness and
superficial resemblance to some kinds of obsidian may at
first sight lend some countenance to such an idea. Never-
theless, it is almost superfluous to add, such a notion is a
totally erroneous one, and the mode in which flint occurs—
without altering the limestone with which it is in contact,
or the fossils which it contains—is of itself sufficient to
refute any such origin.

From the hardness and insolubility of flint, it would
appear a very natural inference that silica in all forms is
likewise insoluble, but, as proved by siliceous springs,
silica in a certain condition is freely soluble in alkaline
waters. This naturally suggested to the earlier geologists
that flints bad been deposited by the aid of hot springs or
heated waters in the cretaceous sea at certain intervals
during the formation of the chalk sea. Thus, the late
Dr Mantell wrote that “the nodules and veins of flints
that are so abundant in the upper chalk have probably
been produced by the agency of heated waters holding
silex in solution, and depositing it when poured into the
chalk sea.” It will, however, be obvious that there are
very serious difficulties in accepting any such explanation.
In the first place, we should require the introduction of
floods of heated water containing silica at certain irregular
intervals during the whole period of the deposition of the
upper chalk ; and it would also be essential that these waters
should have extended over vast areas of ocean. Secondly,
the mode in which nodular flint occurs could not
adequately be explained by any theory of this kind; while
it would leave the origin of the tabular flint, which we have
seen may occur in joints and fissures, totally unaccounted
for. Another idea was that the silica had been, at least
partially, introduced from above after the deposition of the
chalk ; but, although this explanation may, and perhaps
does, partly account for the formation of some of the
upper tabular flints, it is quite impossible that it could

SEGREGATION, 217

explain the formation of the numerous layers of nodular
flints throughout the body of the chalk.

There is, however, an explanation which will readily
account for all the features presented by the chalk-flints,
and requires the aid of no foreign factors in the process.
This explanation is based on the phenomenon known as
segregation. Now segregation is the tendency presented
by a small quantity of one substance, when diffused
through a much larger quantity of another substance, to
collect together in nodules or strings, which generally
accumulate either around some fragment of their own
nature or some foreign body—especially an organic one—
as a nucleus. We have well-known examples of this
segregating process in the huge lenticular calcareous masses
termed “septaria,” found in the London and Kimeridge
clays, and also in the iron-nodules of other formations.
Premising that soluble silica has a peculiar affinity not
only for any kind of silica, but likewise for gelatinous
organic substances (both of which were presented by the
sponges of the cretaceous seas), it will be obvious that if
we can only satisfy ourselves that at the time of its
deposition the chalk contained diffused among its substance
a sufficient amount of soluble silica, we shall at once be able
to account for the formation of its flint. Now, as we pass
upwards in the cretaceous system from the lower green-
sand to the upper chalk, we find a gradual change from
a completely siliceous to a calcareous rock. Moreover,
while in the gault, upper greensand, and lower chalk (in
which in the south of England there are no flints) there
is a large but decreasing amount of soluble silica, varying
from 46 per cent. in the upper greensand to 31 per cent.
in the chalk-marl, when we reach the upper chalk with
flints such soluble silica is reduced to a mere trace. As
it is at the base of the white chalk that the sponges attain
their greatest development, and as it is also here that
flints first commence, the disappearance of the soluble
silica may be safely attributed to its segregation by means
of the sponges and other bodies, and its conversion into
flint. Prof. Prestwich, writing on this subject, observes
that in presence of the siliceous spicules of the cretaceous

218 A FLAKE OF FLINT AND ITS HISTORY.

sponges and their gelatinous animal matter, “the soluble
or colloidal silica, dispersed through the soft chalk-mud,
slowly segregated from out of the surrounding pulpy mass,
and gradually replaced part or the whole of the organic
matter, as it decayed away. Nor has it stopped there;
owing to the affinity of the particles of colloidal silica
amonest themselves, the segregation has not ceased with
the replacement of the organic body, but has continued so
long as any portion of silica remained in the surrounding
soft matrix; whence the frequent excess of flint beyond
the interior or body of the shells, echinoderms, &c., and
whence also the irregular shape arising from this over-
erowth of the flint nodules.” Next to sponges, echino-
derms seem to have afforded the most attractive centres
of segregation; and while in some cases only their shells
have been filled with flint, in other instances we find a
mass of these shells cemented together by a nodule
of flint.

In some parts of the Continent, und also in Yorkshire,
we find that for some reason or other—not improbably a
greater development of sponges and a smaller amount of
soluble silica—the segregating process has extended down-
wards to the lower chalk, where flints are then found; and
we suspect that in such cases analysis would also show in
these beds a corresponding absence of free soluble silica.*

With regard to the so-called “ potstones”’ of the
Norfolk chalk, some of which may be upwards of a yard
in height, with a diameter of a foot or so, the only
adequate explanation of their formation that has yet been
offered is that they represent gigantic cup-like sponges
which have grown one upon the top of the other, as they
were successively buried in the newly-formed chalk, and
that they have been subsequently silicified by the same
segregating process.

We conclude, therefore, that the flints of the chalk were
originally an integral portion of the rock itself, which was

* Since this was written, some observations have been published
tending to throw doubt upon the constancy of the relation between
the absence of flint and the presence of free soluble silica in chalk.

EVIDENCE OF DENUDATION. 219

then a slightly silicated limestone ; and that the present
purely calcareous character of the chalk is due to the
separation of the silica by segregation. We have, however,
still to account for the relatively large amount of soluble
silica present in the cretaceous rocks, since this is far in
excess of what would have been brought down by most
rivers of the present day, in the waters of which the
amount of this substance is almost infinitesimal. It has
been suggested that the unusual supply may have been
afforded by the cretaceous rivers being largely fed by sili-
ceous springs ; but although this may have been one factor
in the case, a more probuble theory is that the drainage
area supplying the cretaceous sea with sediment was
largely composed of decomposed felspathic rocks, in which
the amount of this silica would have been amply sufficient
to have furnished the quantity present in the chalk.

It is, however, not only with regard to its mode of
origin that flint is of more than ordinary interest.
Being an excessively hard substance, it is one exceedingly
difficult to be worn to powder by the action of water, and
the flint-gravels of the valleys of the south of England,
as well as the beaches of our southern coasts, and the
numerous Tertiary deposits composed of flint pebbles,
remain to us as silent witnesses of the vast denudation of
the upper chalk which has taken place in this country.
Remembering that the proportion of flint to chalk is only
from four to six per cent., and also bearing in mind that
all the flints in our gravels have been considerably reduced
in size by the action of water, we may fairly say that
every cubic yard of pure flint gravel represents the
removal of at the very least twenty cubic yards of pure
chalk; and to this we have to add all the lower chalk
which has been denuded without leaving any solid residue.
Moreover, when we recollect that this denuding process
has been going on ever since the Eocene period, and that
our river gravels only represent a small portion of the
flints left by the denudation of the chalk during the latter
part of this protracted period of time, we may gain some
faint conception of how enormous this denudation must
have been.

220 A FLAKE OF FLINT AND ITS HISTORY.

Although the flint-gravels of our rivers afford some
estimate, however faint, of the denudation of the chalk
during the Pleistocene period, it would be quite incorrect
to assume that the flint pebbles forming the beaches of
our southern coasts present a record of the amount of
denudation which has taken place during the modern
period. We have already mentioned that a freshly-broken
flint presents a uniform blackish-blue colour throughout
its interior, and any flint pebble on the seashore which
had been recently. derived from its native chalk would,
when broken, present a similar appearance. As a matter
of fact we shall find, however, that at least nimety per cent.
of such pebbles are stained yellow, brown, red, or black
internally, and since most of the flint fragments in many of
our older gravels are likewise similarly stained, we shall
have little hesitation in coming to the conclusion that our
modern sea-beaches are largely derived from the breaking
up of such old gravel beds, and the subsequent rounding
of these irregular fragments of flint into pebbles by the
action of the sea. The staining of the flints is of course
due to the large amount of ferruginous matter contained
in the gravels, and owing to the banded nature of the
original flint it frequently gives rise to an agate-like
appearance in the pebbles. Many of the pebbles in our
beaches are, however, derived from still older sea-beaches,
like the one now remaining at the southern extremity of
the Isle of Portland, while others, again, owe their origin
to the breaking up of the Eocene Woolwich and Reading
beds, which are largely composed of flint pebbles. Some-
times, indeed, fragments of these old beds also occur in
the river gravels, where blocks of the Hertfordshire con-
glomerate —the equivalent of the Woolwich and Reading
beds—may be met with.

We have thus abundant evidence of the exceeding
indestructibility of flint, and how it may go on from one
formation to another to tell, when rightly interpreted, the
various steps in the denudation of our country.

In addition to being frequently stained internally, the
observer will also not fail to notice that all of the flints
in our river gravels have acquired a white or yellow

DECOMPOSITION OF FLINT. 221

porcelaneous external coating, quite different from the
interior; and it is believed by Sir John Evans that this
white coating has been produced by the removal of a
portion of the flint which was still soluble “by the
passage of infiltrating water through the body of the
flint.” That such a process must have been of incon-
ceivable slowness, and must have required countless years
for its accomplishment, goes without saying. We have,
indeed, some inkling of “how extremely slow this process
must be, from the circumstance that the fractured surfaces
of the flints built into the walls of our very oldest churches
show not the slightest change from their pristine condition.
When, however, we examine the chipped flint implements
of our river gravels and caves, like the one shown in our
first illustration, we find their surfaces altered precisely in
the same manner as the flint fragments by which they are
accompanied. Hence we gain, from a totally independent
source, some idea of the immense antiquity of the period
when the old paleolithic hunters inhabited the south of
England.

Having thus reached the subject of flint implements,
we feel tempted to enter into the consideration of some of
their different types and the beds in which they occur,
but limits of space forbid our wandering into such
entrancing paths. Even, however, without entering into
this part of the subject, we trust that what we have
written will serve to show that a ‘Flake of Flint,” when
considered from all points of view, is to the full as
interesting as a ‘“‘ Lump of Chalk.”

THE END.

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