Читать книгу Natural History: Reptiles - Philip Henry Gosse - Страница 17

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(Crocodiles.)

Messrs, Duméril and Bibron enumerate the following characters as proper to this family. The body is depressed, lengthened, protected on the back with solid and keeled scutcheons, or shields; TOOTH OF CROCODILE. the tail is longer than the trunk, compressed, the plates here set in rings, and rising into a ridge of pointed crests; the limbs are four in number, short; the toes of the hind feet united by a swimming membrane; three claws only on each foot; the head is flattened, lengthened into a muzzle, in the front of which are the nostrils, not far apart, upon a fleshy tubercle, furnished with moveable suckers; the gape opens beyond the base of the skull; the tongue is fleshy, entire, adherent, not protractile; the teeth are conical, simple, hollowed towards the root, unequal in length, but placed in a single row. The cavity at the root of each tooth serves as a case or sheath for the germ of the tooth destined to replace it, which is to be of greater bulk; ​and each being thus gradually pushed out from below by a successor ready to supply its place, the jaws of the Crocodiles present, at all ages, their formidable array of pointed teeth in undiminished number.

The Crocodiles, as we have said, are fierce and voracious, and prove destructive, not only to quadrupeds, (and those of large size), but also to man himself. Cuvier states that they are unable to swallow in the water, but this seems to be unconfirmed. They do, however, commonly resort to the shore for the purpose of devouring those animals which they have seized and drowned, dragging them out again after they have begun to decay. On land their motions are stiff, ungainly, and embarrassed, and a peculiar structure of the vertebræ precludes them from being able to turn themselves with facility. Yet they are able to bound forward with considerable agility, springing to a distance which would scarcely be expected from creatures so unwieldy.

In the water they swim with swiftness both upon and beneath the surface; here they know themselves to be at home, and usually leap into the water with precipitation if surprised on land by even the distant appearance of a man.

These are not only the largest of all reptiles, but are among the most gigantic of animals. Some are reported to have attained a length of twenty-five feet, and it seems probable that they are long-lived, and that their bulk continues to increase with years. The mouth is enormous; and the numerous pointed teeth, thirty or more on each side of each jaw, are so disposed as to fit into the interstices of each other. As the lips are ​altogether wanting, the teeth are visible when the mouth is closed; hence the animal, even when tranquil, seems grinning with rage. A similar expression is communicated to the visage from the eyes, which are placed obliquely near each other, and have a peculiarly fiery glare.

The compressed and dentelated tail, though from its length and weight it impedes the motions of these animals on the land, is yet an organ of the utmost importance to them in the water, where it is a most powerful instrument of progression, and influences their aquatic habits much more than their webbed hind feet. The latter are indeed used, when the animal is paddling with a slow and gentle action; but in sudden and swift motion, as in escaping from an object of alarm, or in energetic pursuit of prey, alternate strokes with the tail upon the element give the powerful impulse. On land, also, the Crocodile is said to use this organ as an efficient weapon of offence, dashing it from side to side with swift contortions, when its weight, its hard rough surface, and especially its saw-like crests, render its strokes eminently formidable. Like the Turtles, the Crocodiles lay their eggs in the sand, and leave them to be hatched by the heat of the sun. The general number is from eighty to a hundred: their size is about that of a goose's egg, but their form is more oblong.

When we consider the vast bulk of the adult animal, we may affirm that no creature exhibits so great a disproportion between its youth and age. The eggs are covered with a hard calcareous shell, like that of birds' eggs, but more shining, harder, and more brittle.

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