Alligator (Fr. alligator, It. alligatore, corrupted from the Sp. el lagarto, the lizard), a large carnivorous, amphibious reptile, of the saurian family, peculiar to America. The name was first given to this animal by the English colonists of the southern portion of what are now the United States, but has been gradually extended to all the varieties of the family, called caymans, crocodiles, jacares, etc, by the Spaniards, Portuguese, and Indians of the southern continent. The alligator was formerly believed to be identical with the crocodile of the old world; but there have subsequently been found to exist distinctions which indicate generic differences. The generic characteristics of the family are long flat heads, thick necks and bodies, protected by regular transverse rows of long plates or shields, elevated in the centre into keel-shaped ridges, and disposed on the back of the neck into groups of different forms and numbers, according to the species. The mouth is extremely large, extending considerably behind the eyes, and furnished in each jaw with a single row of conical teeth, all of different sizes, and standing far apart from one another. The eyes are placed on the upper surface of the skull, very near to each other, and provided with three eyelids.

The feet have five toes before, long and separate; four behind, more or less perfectly connected by membranes; the interior toes only, on all the feet, being provided with claws. The tail is of great length, slender, strongly compressed at the sides, and surmounted toward its origin by a double series of keel-shaped plates, forming two upright denticulated crests, which," gradually converging toward the middle of the tail, there unite and form a single row to the extremity. The tail is the animal's great instrument of progression in the water, and its great weapon of defence when surprised on land. Both genera, alligators and crocodiles, hibernate, taking no food during the winter months; the Nilotic crocodiles, according to Pliny, withdrawing into caves and holes in the banks, while the alligators of America bury themselves in the mud of stagnant rivers. The principal food of both alligators and crocodiles is fish, but they watch for and devour land animals and even men. It is alleged that the musky fluid secreted from the glands of the throat acts as a sort of bait, and attracts the fish on which they prey. The alligators, according to Cuvier, have the head less oblong than the crocodiles.

Its length is to its breadth, measured at the articulation of the jaws, as three to two; the teeth are unequal in length and size; there are at least 19, sometimes even as many as 22, on each side in the lower, and 19 or 20 in the upper jaw. The front teeth of the under jaw pierce through the upper at a certain age; and the fourth from the front, which are the largest of all, enter into corresponding holes of the upper jaw, in which they are concealed when the mouth is closed. The hind legs and feet are round, and neither fringed nor pectinated on the sides; the toes are not completely webbed, the connecting membrane only extending to their middle; and finally, the post-orbital holes of the cranium, so conspicuous in the crocodiles, are very minute in the alligators, or even entirely wanting. Further than this, it is observable that the alligators, unlike the crocodiles, are rarely if ever to be found in running streams, preferring stagnant ponds and the creeks of large rivers, in which, particularly in South America, they may be seen in great numbers, protruding their large flat heads through the leaves of the nymphaea, pontederia, and other aquatic plants, and watching for their prey; or sometimes basking in the sun, or sleeping on the banks.

They rarely come on shore, except during the hottest part of the day, and always retire to the water on the approach of night, during which they are extremely active in search of their food. They generally lay from 50 to 6O eggs in one place, of about the same size as those of the goose, which they cover up with sand, and leave to be hatched by the heat of the sun, never, however, removing to any great distance. when the young ones come forth, they are five or six inches long, and are immediately conducted to the water by the female alligator. Seldom more than half the brood long survive, the remainder being devoured by the male alligators, and by various ravenous fishes; while multitudes arc destroyed in the egg by the vultures. The alligators never leave the fresh water, while the crocodiles frequent the mouths of the large rivers, and swim out into the open sea, passing between different islands at consider- able distances. So perfect a characteristic is this of the two genera, that the animal of the West India islands, which swims out into the salt water, is distinctly a crocodile, varying from all the other American species, and exhibiting the modifications which belong only by right to those of the old world. - The principal species are: 1. The alligator, properly so called, cro-codilus lucius of Cuvier, alligator Mississippien-sis of Gray, inhabiting the waters of the southern states.

It grows to the size of 14 or 15 feet; its head is one seventh of the entire length, and half as broad at the articulation of the jaws as it is long. It has these distinguishing modifications from the crocodiles: The snout is flattened on its upper surface, and slightly turned upward at the extremity; its sides are nearly parallel, and the nose forms a regular parabolic curve. It is from this similarity to the head of a pike that it has its name lucius. It is said to be far more fierce and voracious than the South American species, often seizing and destroying men and large land animals, the bodies of which it conceals under the banks until they begin to putrefy, when it draws them ashore and devours them; for its teeth, unfitted for mastication, cannot cut the flesh in its sound state. The female of this species is remarkable for her maternal attention to her young, never losing sight of her nest until the little alligators are released from the shell. Bartram, the American naturalist, found great numbers of these reptiles in a mineral spring near the Mosquito river, Florida, though the water at its exit from the earth was nearly at the boiling point, and strongly impregnated with copper and vitriol. 2. The cayman, alligator palpebrosus.

This species is distinguished by its bony eyebrows, which form knobs as large as the fists of a man. Its toes are almost entirely free from connecting membranes, and its skull has no post-orbital apertures. It is smaller and less fierce than the others of its genus; and the female takes no heed to her eggs when they are once deposited. This is the alligator of Guiana and Surinam. 3. The alligator of Brazil, alligator trigonatus, a variety of the above species, distinguishable from it by a long ridge between the orbits running toward the snout, a notch in the posterior margin of the skull, and a peculiar arrangement of the cervical plates. 4. The jacare, alligator sclerops. This is the alligator of all tropical America, particularly numerous in Brazil. Its head is more elongated than that of the North American alligator, the sides converging toward the snout so as to form nearly an isosceles triangle. The bones of the skull have a rough scabrous appearance, as if diseased; and the orbits of the eye are surrounded by prominent rims of bone, connected by a ridge between the orbits, constituting together the resemblance of a pair of spectacles, whence its name. It grows to a very large size, attaining even to 18 feet, its length being more than eight times that of the head.

It never attacks men, or even dogs, whether on land or in passing rivers, unless in the neighborhood of its nest; nor does it then prey on the carcasses, feeding only on fish and water fowl. - The bony armor of all the species is their protection against all enemies. It is proof against the rifle ball, which can only take effect when it strikes the eye, or the unarmed skin on the belly and about the insertion of the fore legs. The construction of this armor, however, prevents them from turning rapidly when on dry land, so that their pursuit is easily avoided. Their flesh, and even their eggs, al-though both have a strong musky flavor, are said to be both wholesome and nutritious. The American alligators have neither their allied protector bird, the spur-winged dotterel, nor their characteristic enemy, the ichneumon, which protect or assail the crocodile of the Nile. The hideous aspect, disgusting habits, abominable smell, and odious roar of these reptiles have rendered them objects of undue apprehension. (See Crocodile.)