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attained a development which it never equalled before or since. The Dinosaurs,
which were by far the largest of all land animals, then filled the place now
occupied by Mammals ; the flying dragons played the rdle of the bats and birds of
the present day ; while the marine Plesiosaurs and fish-lizards did duty for whales
and porpoises. Of the mammal-like Reptiles, it will suffice to speak in the sequel.
With regard to the past distribution of the four existing orders, it may be
mentioned that the lizards and snakes, with the exception of two extinct suborders,
are practically unknown before the commencement of the Tertiary period that is
to say, until after the deposition of the Chalk ; hence they may be regarded as
essentially the Reptiles of the present day, when they attain their maximum
development. The tortoises and turtles, although a much more ancient group,
having existed throughout the Secondary period, are, however, still at or about
their zenith. The case is, however, very different with the crocodiles, which were
represented during the Secondary period by a host of forms quite unlike those of
the present day, and probably more numerous in species than their existing
representatives. Many of the extinct crocodiles also exceeded any of the living
forms in point of size. Still more markedly is this diminution noticeable in the
case of the tuateras, in which a solitary survivor represents a once abundant
group.

Owing to the exigencies of space, our remarks on the present distribution of
the class must necessarily be brief. In the first place, it may be observed that
while no existing Reptiles are denizens of the air, only the turtles and sea-snakes
are habitual inhabitants of the ocean. Of the terrestrial and fresh-water forms, it
has been found that the distribution does not coincide very closely with that of
Mammals and Birds, so that the zoological regions into which the globe has been
mapped out from the geographical distribution of the latter scarcely hold good
for Reptiles. This discrepancy may, no doubt, be partly explained by the very
early period at which certain groups of the class, such as crocodiles and tortoises,
spread themselves over the surface of the globe. As regards the dispersive powers
of Reptiles in general, these, according to Dr. Giinther, are but limited. All these.
creatures, he writes, " are much specialised in their mode of life and propagation,
and ill-adapted to accommodate themselves to a change of external conditions.
As air-breathing, cold-blooded animals they are unable to withstand prolonged
cold; they are therefore entirely absent in the Arctic and Antarctic zones; and
such as escape the effects of the winter months in temperate zones by passing
them in a torpid condition in well-sheltered places are not peculiarly
organised forms, but offshoots from those inhabiting warmer climes. The tropical



DISTRIBUTION. 9

md subtropical zones are the real home of the reptilian type, which there has
reached its greatest development as regards size and variety of forms. In the

lorth, Chelonians advance only to 50 latitude in the Western and to 56 in the
stern Hemisphere ; lizards to about 56 in British Columbia, and close to the

Arctic Circle in Europe ; while snakes disappear some degrees before the lizards.

Iso in the south, lizards extend into higher latitudes than snakes, namely, to the

Straits of Magellan, whilst the latter do not seem to have advanced beyond 40

rath latitude, and Chelonians to 36."

Of the various zoological regions into which the globe has been divided, the

)riental or Indian region, according to the same observer, is characterised by the
mmber of fresh-water soft-tortoises 1 and S-necked tortoises, 1 land-tortoises being

2arce. Crocodiles, inclusive of the characteristic long-necked garials, are numerous,
are lizards and snakes especially pythons. Africa is comparatively poorly off
for Reptiles, although characterised by its numerous land-tortoises, soft-tortoises,
md side-necked tortoises ; l the crocodiles being represented only by members of
the typical genus ; while lizards and snakes are comparatively numerous. Among
the lizards, monitors, and among the snakes, pythons, are common to the Oriental
md African regions ; while half of the exclusively Old World group of chamseleons
ire African. Madagascar is even more remarkable for the number of its

lamseleoiis; its land and side-necked tortoises are numerous, although soft-

>rtoises, as in South America, are absent ; there is one crocodile ; and among the
izards the South American group of iguanas is abundant; while the snakes,
rniong which none is poisonous, are also of a South American type. In the

farmer parts of the Euro-Asiatic region (exclusive of India, etc.) the reptile fauna
mainly a mixture of Oriental and African types, although there are some
jeculiar forms. The only non-American alligator inhabits Central China. In
the Australian or tropical Pacific region, exclusive of New Zealand, we meet with
)ne group of land-tortoises, side-necked tortoises, and a crocodile ; while amongst

le lizards there are skinks, geckos, monitors, and the so-called agamoids; the

itter occurring in all the regions above mentioned, except Madagascar. Venomous

lakes here outnumber the harmless ones. The Tropical and South American

3gion is characterised by the presence of land and side-necked tortoises, to the
exclusion of soft-tortoises. Crocodiles and caimans are numerous (the latter being
characteristic) ; while of the abundant lizards the majority are iguanas, the true

sards (Lacertidcv) of the Old World being replaced by the teiias (Teiidce);

lakes are also numerous, among them being rattle-snakes and boas. In the
North American region there are no caimans, their place being taken by an
alligator ; while fresh- water S-necked tortoises, as well as soft-tortoises, replace the
side-necked tortoises of the southern half of the continent. The snapping tortoises
(Chelydridcv) are also mainly characteristic of this region, although one genus
ranges as far south as Ecuador. As regards its lizards and snakes, this region
presents the same relation to the preceding as is held by Euro- Asia to the Oriental
and African regions. Lastly, New Zealand stands apart from all other countries
in possessing the remarkable tuatera, in addition to which its only reptiles are
skinks and geckos.

1 For the explanation of these and other names, the reader must refer to later chapters.



CHAPTER II.

CROCODILES, DINOSAURS, and FLYING DRAGONS, Orders CROCODILTA.
DINOSAURIA, and ORNITHOSAURIA.

THE living crocodiles, among which may be included in a general sense not only
the reptiles to which that name more properly belongs, but likewise those
commonly designated alligators, caimans, and garials, are the only existing
representatives of three orders, which comprise among their members not only
the most highly organised of all Reptiles, and those which approach nearest in
their organisation to Birds, but likewise the largest of all terrestrial Reptiles, as,
indeed, of any land animals. Although these three orders possess many character-
istics in common, it will be more convenient to describe the leading features of
each separately, in the course of which their common attributes will be pointed out.




SKELETON AND ABDOMINAL HIBS OK CROCODILE.



Characteristics Sluggish in disposition, hideous in form, and huge in si>

of Crocodiles, crocodiles alone among existing Reptiles serve in some measure to
ree.all (lie n-iant Saurians with which the earth was peopled during earlier periods
of its existence. In addition to their large bodily size, crocodiles are characterised
by the lizard-like form of their bodies, which are supported on short limbs, and
carried close to the ground. The long and powerful tail is much compressed from
side to side, so as to be an efficient propeller in swimming: its superficial extent
being increased by a vertical longitudinal en-si on its upper surface, this crest



GENERAL CHARACTERISTICS. , 3

; being formed of a double series of horny lobes in the basal half of the tail, beyond
which it is single. The head terminates in a flattened snout of variable length,
and is attached to the body by a short, although muscular neck ; while the bulky
body is much depressed. The toes are more or less webbed. Externally, the back,
tail, and under-parts of these animals are protected by an armour of quadrangular
horny shields of varying size, which are arranged in regular longitudinal and
transverse rows, and are in contact with one another by their edges. In the
region of the back, and sometimes also on the under surface of the body, these
horny shields are underlain by a corresponding series of pitted bony plates. In
the region of the neck, among existing members of the order, these bony plates
are often irregular in form, and vary in number, but on the back they are always
quadrangular and broader than long, with a well-marked longitudinal ridge down
the middle. Such plates form a considerable number of longitudinal rows ; each
plate articulating by its edges with those on either side, while those of each
transverse row overlap those immediately behind them. When a bony shield is
developed on the under surface of the body, the number of longitudinal rows of
plates in existing forms is always more than eight ; the transverse rows of plates
overlapping and each plate being composed of two distinct pieces united together
by suture. The limbs are provided with five toes in front and four behind ; the
three innermost digits in each foot being furnished with claws. In all crocodiles,
whether living or extinct, the conical teeth, which may be of very large size, are
confined to the margins of the jaws, where they are implanted in distinct sockets ;
while those in use are continually being replaced by fresh ones growing from
beneath. These animals are further characterised by their nostrils opening at the
extremity of the snout which may be either short or long and by their ears being
covered with movable lids.

Such are some of the leading external features of these reptiles, and although
y would suffice to distinguish them from the living members of the order,
they are insufficient to determine their true affinities. Laying stress upon the
above-mentioned characters of their teeth, the naturalist is accordingly compelled
to resort to the skeleton and soft internal parts for more distinctive characters.
In the skull all crocodiles are characterised by the quadrate-bone (of which the
position is indicated in the figure on p. 2) being firmly united with the adjoining
bones ; while a further distinctive feature is to be found in the presence of two
bony bars on the sides of
the skull behind the socket
for the eye, the uppermost
of these arches being shown
immediately below the

letter T in the accompanv-

7 SIDE VIEW OF SKULL OF EXTINCT CROCODILE (Pelagosaurus).

ing figure, while the lower 0> socket for the eye . T> tempora i pit or fossa .

and more slender one forms

the backward continuation of the inferior margin of the eye-socket. The more

anterior ribs (which, as in other Reptiles, are present in the neck as well as in the

chest) generally articulate with the backbone by means of two distinct heads;

and, while collar-bones are wanting, there is a breast-bone and likewise an inter-




i 4 CROCODILES.

clavicle ; the latter being the median bar seen in the lower figure of the illustration
on p. 10. A further peculiarity is the presence of seven or eight pairs of abdominal
ribs in the wall of the abdomen, which have no connection with the proper ribs,
and have their angle of union directed forwards. 1 As regards the soft parts, the
heart differs from that of all other living Reptiles in having four complete chambers,
so that the fresh and impure blood can only mingle by means of a communication
between the great vessels externally to the heart ; while there is also an incomplete
midriff dividing the chest from the abdomen.

In addition to the preceding characters, which are common to all members of
the order, there are certain others found only in the existing forms and some
of their nearest extinct allies. One of 'the most remarkable of these peculiarities
is the extremely backward position of the aperture of the internal nostrils, which
in the dried skull, as shown on p. 2, is situated close up to the occiput, this being
due to the development of special plates by the bones of the palate, which gr< w
beneath the nasal passage, so as to form a floor to it, and thus completely cut it
off from the cavity of the mouth. As the summit of the windpipe is continued
upwards into this posterior aperture of the nostrils, crocodiles are enabled to
breathe while their mouths are wide open and filled with water. Another dis-
tinctive feature of the group, also shown in the figure just referred to, is that the
socket for the eye communicates freely behind with the lower temporal fossa.
Then, again, all existing members of the order are characterised by the bodies of
the vertebrae having the ball behind and the cup in front ; while the ribs of the
chest are provided with hook-like or uncinate processes resembling those of birds.
In the region of the neck the ribs present the peculiarity of having backwardly
projecting and overlapping processes, which effectually prevent these animals from
turning their heads to one side.

Crocodiles are denizens of the tropical and subtropical regions of
Habits

the globe, and are found in such latitudes wherever there are rivers

or fresh-water lakes of sufficient size for their mode of life ; while one of the
Indian species habitually resorts to the sea-coast, where it has been seen floating at
a considerable distance from the land. All of them are excellent swimmers, and
are mainly propelled when in the water by the aid of their powerful tails ; the
limbs being chiefly used when walking at the bottom of the water, or on the shore.
When in repose, crocodiles lie like logs either in the water or on the banks of the
lakes or rivers they inhabit; but when in pursuit of their prey in the water they
move with great speed, while they are also active on land. The young are,
however, decidedly nimbler in their movements than are the adults. Exclusively
carnivorous in the diet, some members of the order feed solely upon fish ; while
others, in addition to fish, prey upon the flesh of all animals that come in their
way. Adult crocodiles, writes Dr. Giinther, " attack every large animal which
accidentally approaches them, and in overpowering it the whole of their powerful
organisation is called into requisition. Seizing the victim between their capacious
jaws, and fastening their long, pointed, conical teeth into its flesh, they draw it,
in one moment, by their weight and with a stroke of the tail, below the water and
drown it. Their gullet is, however, much too narrow to allow of the passage of

1 These abdominal ribs, connected together by the ligament, are shown in the figure above referred to.



EXISTING GROUP. 15

the entire body of the victim; and their teeth being adapted for seizing and
holding fast only, and not for biting, they are obliged to mangle the carcase,
tearing off single pieces by sudden strong jerks." This rending process is mainly
accomplished by lateral movements of the head and front portion of the body.
Too often, human beings, who incautiously bathe in crocodile-haunted waters, fall
victims to these bloodthirsty reptiles ; while there are instances of people being
seized when merely stooping down to dip water from the river's marge. When
seized, the only way for an unarmed man to escape is, it is said, to thrust his

*?ers into the creature's eyes and endeavour to gouge them out. To a consider-
e extent crocodiles are nocturnal in their habits, and during protracted droughts
many of them at least are accustomed to bury themselves in the mud, where they
become torpid.

As regards their reproduction, crocodiles lay from twenty to sixty eggs, of
the approximate size of those of a goose, and invested with a hard, white shell.
These are deposited in some hollow in the sand of the bank, where, after being
covered to a greater or less depth, they are left to hatch. Whether the parent
;il \vays assists in the incubation does not appear certain, although this has been
proved to be the case in Madagascar by Dr. Voeltzkow. In that island the egg-

*7ing season lasts from the end of August to the end of September ; the usual
mber of eggs in a nest varying from twenty to thirty. The nest is excavated
to a depth of about two feet in the dry white sand ; its lateral walls being under-
mined so as to allow the eggs to roll into the cavities thus formed from the
slightly elevated centre. Upon the summit of the completed nest, which is not
noticeable externally, the parent sleeps ; and when the young crocodiles are ready
for hatching they utter distinct notes, which are heard by the mother even
through a layer of two feet of sand. Digging down to the eggs, the parent
crocodile lays them open to the air, upon which the young reptiles make their
way Out by perforating the shell at one extremity by the aid of a tooth specially
eveloped for this purpose, the whole process occupying as much as a couple of
>urs. When hatched, the young crocodiles are led to the water by their parent,
ose attention they attract by uttering cries, which are, however, of a lower
ch than those emitted while still in the egg.



EXISTING CROCODILES.
Family GnOGODILID^E.

. The whole of the existing members of the order are included

Caimans.

in a single family, which may be subdivided into half a dozen generic

groups. Of these, in some respects the most specialised are the caimans and
alligators, which, although closely allied, are now generally regarded as belonging
to distinct genera. Both caimans and alligators are characterised by their rela-
tively short and broad snouts, in which the edges of the jaws are festooned, and
the nasal bones extend forwards to the aperture of the nostrils, 1 while the two

1 This is shown in the figure on p. 2, where the nasals are the paired bones on the upper aspect of the skull, of
which the narrow points just project into the cavity of the nostrils.



i6



CROCODILES.



halves of the lower jaw are united in front by a very short bony union. The
stout teeth vary considerably in size in different parts of the jaws ; the third and
ninth in the upper jaw, the fourth, and frequently also the first and eleventh, in
the lower, being generally much larger than the others. In these features caimans
and alligators resemble many of the true crocodiles ; from which they are distin-
guished by the circumstance that, as a rule, both the first and the fourth tooth on
each side of the lower jaw are received into pits in the upper jaw, so as to be
invisible externally when the mouth is closed ; while the upper teeth bite on the
outer side of the lower ones. Moreover, the number of teeth varies from seventeen




SPECTACLED CAIMAN (^ nat. size).



to twenty on each side of the upper jaw, and from seventeen to twenty-two in
the lower jaw. Then, again, both these groups are characterised by the very small
size of the upper temporal fosse on the top of the skull, or those marked T in the
figure on p. 13 ; these fossae being in some cases completely obliterated. Caimans
are specially distinguished by t\ .perture of the nostrils not being divided in two
by the nasal bones, by the presence of a strongly developed bony armour on the
inferior surface of the body, and by the bony plates on the upper surface being
articulated together.

Caimans, or jacares, as they are called by the natives of Brazil, are restricted
to Central and South America, where they are represented by five species. Of
these, the largest, and at the same time the best known, is the black or givat



CAIMANS. 1 7

caiman (Caiman niger), from the rivers of tropical South America eastwards of
the Andes, which takes its name from the black of the upper surface of the body,
the under-parts being yellow. This species, which generally attains a length of
about 14 feet, is characterised by its partially bony and flat upper eyelid, by the
presence of upper temporal fossse in the skull, by the number of teeth in each
premaxillary or anterior upper jawbone being five, and the number of lower teeth
being seventeen or eighteen. Nearly allied, although of much smaller size, are
the broad-nosed caiman (C. latirostris), ranging from the Amazon to the Rio de
la Plata, and the spectacled caiman (6^. sclerops), from Central and South America ;
both of which have the upper eyelid rugose, with a small horn-like projection,
while in the skull the socket of the eye does not extend so far forwards. Both are
uniformly blackish when adult ; but in the former the skull is very wide, and the
number of lower teeth from seventeen to eighteen, while in the latter the skull is
narrower, and the lower teeth vary from eighteen to twenty. The two remaining
species (C. trigonatus and C. palpebrosus) are still smaller, and characterised by
the colour of the upper-parts being yellowish brown, spotted and barred with
black ; while the upper eyelid is completely bony, the skull has no upper temporal
fossa, there are but four teeth in each premaxillary bone, and the number of lower
teeth is from twenty to twenty-two on each side.

On the Amazon and Orinoco, as well as other South American rivers, caimans
are to be met with in myriads, and appear to be very similar in their habits to the
crocodiles of the Old World. Writing of the great caiman jacare-uassu of the
natives Bates says that " it grows to a length of eighteen or twenty feet, and
attains an enormous bulk. Like the turtles, the alligator [as he calls it] has its
annual migrations, for it retreats to the interior pools and flooded forests in the
dry season. During the months of high water, therefore, scarcely a single in-
dividual is to be seen in the main river. In the middle part of the Lower Amazon,
about Obydos and Villa Nova, where many of the lakes with their channels of
communication with the trunk stream dry up in the fine months, the alligator
buries itself in the mud and becomes dormant, sleeping till the rainy season returns.
On the Upper Amazon, where the dry season is never excessive, it has not this
habit. It is scarcely exaggerating to say that the waters of the Solimoens are as
well stocked with large alligators as a ditch in England is? in summer with tadpoles."
By the natives of these regions the caiman is at once despised and feared ; the
same traveller relating how on one occasion he saw a party boldly enter the water
and pull to shore one of these large reptiles by its tail ; while at another time two
medium-sized specimens that had been captured in a net were coolly returned to
the water hard by where a couple of children were playing. Sometimes, however,
they have to pay dearly for such temerity. The Indians of Guiana, according to
Waterton, capture the caiman by means of a>> waited hook and line, the former
being composed of several pieces of wood, which become fixed in the creature's
jaws. Waterton's account of his ride on the back of a caiman thus caught is
probably familiar to many of our readers ; and we have read of a similar feat being
accomplished elsewhere. The eggs of the great caiman, which are about the size
of those of a turkey, are said to be not unfrequently deposited in a heap of dry
leaves, and are much sought after as food by the natives of Dutch Guiana.

VOL. V. 2



1 8 CROCODILES.

The early Spanish settlers of South America on meeting with a
gigantic lizard-like reptile naturally applied to it the name of una
lagarta, which is the Spanish term for a lizard ; and this as naturally became in
course of time corrupted into alligator. It would appear, indeed, that this name
was first given to the caiman, to which in strict propriety it should therefore
belong ; but now, by the common consent of naturalists, it is taken as the special
designation of the members of the present genus. The alligators, as thus restricted,
are represented by one species from North America, and by a second from the
Yang-tse-Kiang in China ; while there is also a third and imperfectly known
species, of which the habitat is as yet undetermined. The alligators differ from
the caimans merely by the forward prolongation of the nasal bones of the skull,
so as to divide the aperture of the nostrils into two equal moieties, by the want
of articulation between the bony plates of the back, and the absence or extreme



Online LibraryRichard LydekkerThe new natural history (Volume 5) → online text (page 3 of 62)