While most of the Feræ live on land, some are strictly aquatic. The true seals, fur-seals, sea-lions, and walruses comprise the aquatic forms, all being inhabitants of the ocean. The true seals, of which the common harbor seal (Phoca vitulina) is our most familiar representative, have the limbs so thoroughly modified for swimming that they are useless on land. The fur-seals, sea-lions, and walruses use the hind legs to scramble about on the rocks or beaches of the shore. The fur-seals (fig. [157]) live gregariously in great rookeries on the Pribilof or Fur Seal Islands, and the Commander Islands in Bering Sea.

The bears are represented in our country by the widespread brown, black, or cinnamon bear (Ursus americanus) and the huge grizzly bear (U. horribilis) of the West. The great polar bear (Thalarctos maritimus) lives in arctic regions. The otters, skunks, badgers, wolverines, sables, minks, and weasels compose the family Mustelidæ, which includes most of the valuable fur-bearing animals. Some of the members of this family lead a semi-aquatic or even strictly aquatic life and have webbed feet. The wolves, foxes, and dogs belong to the family Canidæ. The coyote (Canis latrans), the gray wolf (C. nubilus), and the red fox (Vulpes pennsylvanicus) are the most familiar representatives of this family, in addition to the dog (C. familiaris), which is closely allied to the wolf. "Most carnivorous of the carnivora, formed to devour, with every offensive weapon specialized to its utmost, the Felidæ, whether large or small, are, relatively to their size, the fiercest, strongest, and most terrible of beasts." The Felidæ or cat family includes the lions, tigers, hyenas, leopards, jaguars, panthers, wildcats, and lynxes. In this country the most formidable of the Felidæ is the American panther or puma (Felis concolor). It reaches a length from nose to root of tail of over four feet. Its tail is long. The wildcat (Lynx rufus) is much smaller and has a short tail.

Fig. 157.—The Lukanin rookery of fur seals, Callorhinus alascanus, on St. Paul Island, Pribilof Group, Bering Sea. (Photograph from life by the Fur Seal Commission.)

The man-like mammals (Primates).—The Primates, the highest order of mammals, includes the lemurs, monkeys, baboons, apes, and men. Man (Homo sapiens) is the only native representative of this order in our country. All the races and kinds of men known, although really showing much variety in appearance and body structure, are commonly included in one species. The chief structural characteristics which distinguish man from the other members of this order are the great development of his brain and the non-opposability of his great toe. Despite the similarity in general structure between him and the anthropoid apes of the Old World, in particular the chimpanzee and orang-outang, the disparity in size of brain is enormous.

Fig. 158.—"Bob Jordan," a monkey of the genus Cercopithecus. (Photograph from life by D. S. Jordan.)

The lowest Primates are the lemurs found in Madagascar, in which island they include about one-half of all the mammalian species found there. The brain is much less developed in the lemurs than in any of the other monkeys. The monkeys and apes may be divided into two groups, the lower, platyrrhine monkeys, found in the New World, and the higher, catarrhine forms, limited to the Old World. The platyrrhine monkeys have wide noses in which the nostrils are separated by a broad septum and with the openings directed laterally. These monkeys are mostly smaller and weaker than the Old World forms and are always long-tailed, the tail being frequently prehensile. They include the howling, squirrel, spider, and capuchin monkeys common in the forests of tropical South America. The catarrhine monkeys have the nose-septum narrow and the openings of the nostrils directed forwards, and the tail is wanting in numerous members of the group. They include the baboons, gorillas, orang-outangs, and chimpanzees. These apes have a dentition approaching that of man, and in all ways are the animals which most nearly resemble man in physical character.