The Reptile Class, as defined by modern scientific limitations, includes among the living animals of the world the several groups of the Crocodiles, the Tortoises and Turtles, the Tuatera, the Lizards, and the Snakes. In the popular mind the Frogs and Toads, and the Newts and Salamanders, are often held to belong to the same main section; but these, as hereafter shown, claim, as Amphibians, an independent position of equivalent rank and value. In bygone geological ages the Reptile Class embraced a considerably larger number of groups; some of the members, such as the extinct Dinosaurs, comprised titanic monsters from 60 to 80 feet in length. The Crocodiles and Alligators of the present day are the only living reptiles which in any way approach the extinct Saurians in their dimensions, or assist us in some small measure to realise their unwieldy forms and bulk.
The members of the Crocodile Order, which, in addition to the Alligators, includes also the Caimans and so-called Gavials or Garials, agree with one another in the more or less ponderous lizard-like shape of their body, supported on well-developed but short and comparatively weak legs, in their special adaptation to an amphibious existence, carnivorous habits, and restriction to tropical and subtropical climates.
Photo by W. P. Dando, F.Z.S.] [Regent's Park.
YOUNG NILE CROCODILE.
This species was worshipped with divine honours and mummified after death by the ancient Egyptians.
Among the salient characters of the Crocodile, as the representative of its tribe, which specially adapt it for its aquatic habits, the long, powerful tail is strongly compressed and thus fitted for use as an organ of propulsion, and the feet are more or less webbed. The most striking of its structural adaptations is, however, associated with the formation of the creature's skull. The manner in which a crocodile or alligator contrives to breathe or to save itself from asphyxiation, when opening and shutting its mouth under water, as it may often be observed to do in the Regent's Park Menagerie, is a common source of wonderment to the onlooker. This seemingly difficult feat is compassed by virtue of the posterior nostrils, or breathing-passages, being set so far back in the skull, and being so completely cut off from the mouth-cavity by specially developed bones of the palate, that they have no intercommunication with the mouth. It is this mechanism which enables a crocodile to seize and hold an animal underneath the water between its open jaws until it is drowned. Special valves at the back of the mouth prevent any water running down the creature's throat, while it is able itself to breathe unrestrainedly by allowing just the tip of its elongated snout, with the anterior nostril-apertures, to remain above the water's surface. In many species a conspicuous knob-like bony excrescence is developed at the extremity of the snout, by which the nostril-openings are raised turret-wise above the surface of the water. The eyes also being usually elevated above the level of the creature's head, the crocodile is able to approach its floating or bank-side prey practically unperceived, its huge body, limbs, and even the head, with the exception of the nose and eyes, being totally submerged.
Photo by W. P. Dando, F.Z.S.] [Regent's Park.
YOUNG BROAD-SNOUTED CROCODILE.