The order of lizards is separated into families. The family to which the alligators, crocodiles, and gavials belong, is called by naturalists CROCODILO. The distinctions which govern the separation of the family CROCODILO into the three genera of alligators, crocodiles, and gavials, consist of peculiarities in the shape of the head, in the peculiar arrangement of the teeth, webbing of the feet, and in some minor characteristics; for, outside of these not very important anatomical differences, the habits of the three kinds of reptiles are in most respects quite similar, some of the species being more ferocious, and consequently more dangerous, than others. The alligator, also called caiman by the Spanish-American creoles, inhabits the rivers and bayous of the North and South American continents, while the crocodiles are natives of Africa, of the West Indies, and of South America. The fierce gavial genus is Asian, and abounds in the rivers of India. The alligator (A. Mississippiensis) and the crocodile (C. acutus) are the only species which particularly interest the people of the United States, for they both belong to our own fauna. Our alligator inhabits the rivers and swampy districts of the southern states. I have never heard of their being found north of the Neuse River, though they probably ascend in small numbers some of the numerous rivers and creeks of the northern side of Albemarle Sound in North Carolina. The bayous and swamps of Louisiana and the low districts of Florida are particularly infested with these animals. The frequent visits of man to their haunts makes them timid of his presence; but where he is rarely or never seen, the larger alligators become more dangerous. During warm, sunny days this reptile delights in basking in the sunlight upon the bank of a stream for hours at a time. At the approach of man he crawls or slides from his slimy bed into the water, but if his retreat be cut off; or he become excited, a powerful odor of musk exudes from his body. During the winter months he hibernates in the mud of the bayous for days and weeks at a time. When the alligator enters the water, a pair of lips or valves close tightly, hermetically sealing his ears so that even moisture cannot penetrate them. His nostrils are protected in the same way.