ALLIGATOR, (probably derived from the Spanish el lagarto, the lizard), an animal so closely allied to the crocodile that some naturalists have classed them together as forming one genus. It differs from the true crocodile principally in having the head broader and shorter, and the snout more obtuse ; in having a large canine tooth of the under jaw received, not into an external furrow, but into a pit formed for it within the upper one ; in wanting a jagged fringe which appears on the hind legs and feet of the crocodile; and in having the toes of the hind feet webbed not more than half-way to the tips. The principal species, all found in America only, are the common alligator (Alligator Mississippiensis or Crocodileis Lucius), occurring in the southern United States ; the caiman or cayman (A. palpebrosus), in Surinam and Guiana ; and the spectacled alligator or jacare (A. sclerops), principally in Brazil. The names alligator and crocodile are often confounded in popular speech ; and the structure and habits of the two animals are so similar that both may be conveniently considered under the heading CROCODILE.