Monkeys, Apes, and Man.—Study the figures ([399], [400]); compare apes and man and explain each of the differences in the following list: (1) feet, three differences; (2) arms; (3) brain case; (4) jaws; (5) canine teeth; (6) backbone; (7) distance between the eyes.
A hand, unlike a foot, has one of the digits, called a thumb, placed opposite the other four digits that it may be used in grasping. Two-handed man and four-handed apes and monkeys are usually placed in one order, the Primates, or in two orders (see table, page [193]). The lowest members of this order are the lemurs of the old world. Because of their hands and feet being true grasping organs, they are placed among the primates, notwithstanding the long muzzle and expressionless, foxlike face. (Fig. [402].) Next in order are the tailed monkeys, while the tailless apes are the highest next to man.
Fig. 403.—Broad-nosed Monkey. × ⅒. America.
Fig. 404.—Narrow-nosed Monkey. × ¹⁄₁₂. Old World.
Fig. 405.—Gorilla. (Size of a man.)
The primates of the New World are all monkeys with long tails and broad noses. They are found from Paraguay to Mexico. The monkeys and apes of the Old World have a thin partition between the nostrils, and are thus distinguished from the monkeys of the New World, which have a thicker partition and have a broader nose. (Figs. [403], [404].) The monkeys of America all have six molar teeth in each half jaw (Fig. [352]); the monkeys and apes of the Old World have thirty-two teeth, which agree both in number and arrangement with those of man.
