Our only native hog is the peccary, found in Texas (Fig. 393). In contrast with the heavy domestic hog, it is slender and active. It is fearless, and its great tusks are dangerous weapons. The swine are the only ungulates that are not strictly vegetable feeders. The habit of fattening in summer was useful to wild hogs, since snow hid most of their food in winter. The habit has been preserved under domestication. Are the small toes of the hog useless? Are the “dew claws” of cattle useless? Will they probably become larger or smaller? _Order?_ [Illustration: FIG. 394.—BIRD. ] [Illustration: FIG. 395.—HORSE. ] [Illustration: FIG. 396.—OX. ] [Illustration: FIG. 397.—DOLPHIN. ] [Illustration: FIG. 398.—FISH. ] [Illustration: FIG. 399.—MAN. ] [Illustration: FIG. 400.—CHIMPANZEE. (See Fig. 406.) ] =Illustrated Study of Vertebrate Skeletons=: Taking man’s skeleton as complete, which of these seven skeletons is most incomplete? Regarding the fish skeleton as the original vertebrate skeleton, how has it been modified for (1) walking, (2) walking on two legs, (3) flying? Which skeleton is probably a degenerate reversion to original type? (p. 209.) How is the horse specialized for speed? Do all have tail vertebræ, or vertebræ beyond the hip bones? Does each have shoulder blades? Compare (1) fore limbs, (2) hind limbs, (3) jaws of the seven skeletons. Which has relatively the shortest jaws? Why? What seems to be the typical number of ribs? limbs? digits? Does flipper of a dolphin have same bones as arm of a man? How many thumbs has a chimpanzee? Which is more specialized, the foot of a man or that of a chimpanzee? Is the foot of a man or that of a chimpanzee better suited for supporting weight? How does its construction fit it for this? Which has a better hand, a man or a chimpanzee? What is the difference in their arms? Does difference in structure correspond to difference in use? Which of the seven skeletons bears the most complex breastbone? Which skeleton bears no neck (or cervical) vertebræ? Which bears only one? Are all the classes of vertebrates represented in this chart? (p. 125.) [Illustration: FIG. 401.—SACRED MONKEY OF INDIA (_Semnopithecus entellus_). × ¹⁄₁₂. ] [Illustration: FIG. 402.—LEMUR (_Lemur Mongoz_). × ⅒. Which digit bears a claw? ] =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.