Alligator, a genus of crocodilian reptiles, constituting a family (Alligatoridae), used also for any individual of the first section described-below. They range from the Lower Mississippi and Texas through tropical America, with one Chinese species (A. sinensis). The head is shorter and broader than in the true crocodile; the teeth are very unequal, and the first and fourth teeth in the lower jaw fit into cavities in the upper jaw; the hind legs and feet are round, neither fringed nor pectinated at the side, and the toes only partially webbed. The genus may be divided into three sections - true Alligators, Caimans, and Jacares (to which some systematists give generic rank, while others combine the Caimans and Jacares in a single section). The best known species of the first section is the Pike-headed Alligator (A. mississippiensis), from the region of the Mississippi. It is from 14 to 15 feet long, of which the head is about one-seventh - greenish-brown above, yellow beneath, with alternate bands of these colours on the sides; the snout is broad, flat, and rounded in front; the nostrils are separated by a bony knob; the armour of the back is not articulated, none on the ventral surface; eyelids fleshy. The Chinese species belongs to this section, and is closely allied to the Pike-headed Alligator, but has the bony plate in the eyelid like the Caimans. The first notice of the existence of a Chinese crocodilian appeared in the Proceedings of the Zoological Society, in 1870. Some nine years later a stuffed specimen was sent to the Paris Museum; and in 1890 two living specimens were received and exhibited at the Zoological Gardens, Regent's Park. The Caimans range from Mexico through tropical South America; the head is high, angular, and flat at the sides; nostrils undivided; eyelids strengthened hy an internal bony plate; bony dorsal and ventral scales articulated; webbing between toes rudimentary. The Jacares, with numerous species ranging from 2 to 13 feet in length, have the same geographical range as the caimans, from which they differ little, except in having fewer teeth, and the eyelids striated or rugose. Their flesh is often eaten. In structure and general habits these animals resemble the crocodile. They feed principally on fish, but Bates describes them as troublesome in the dry season, when "there was always one or two lying in wait for anything that might turn up at the edge of the water." Alligator oil is utilised by the Indians for burning in lamps, and the skin forms the "crocodile leather" of commerce.