FIG. 389.—OKAPI. This will probably prove to be the last large mammal to be discovered by civilized man. It was found in the forests of the Kongo in 1900. =Questions=: It shows affinities (find them) with giraffe, deer, and zebra. It is a ruminant ungulate (explain meaning—see text). ] The true _gastric juice_ is secreted only in the fourth stomach. Since the cud or unchewed food is belched up in balls from the round “honeycomb,” and since a ball of hair is sometimes found in the stomach of ruminants, some ignorant people make the absurd mistake of calling the ball of hair the cud. This ball accumulates in the paunch because of the friendly custom cows have of combing each other’s hair with their rough tongues, the hair sometimes being swallowed. Explain the saying that if a cow stops chewing the cud she will die. [Illustration: FIG. 390.—AFRICAN CAMEL (_Camelus dromedarius_). ] [Illustration: FIG. 391.—PRONG-HORNED ANTELOPE (_Antelocarpa Americana_). ] Does a cow’s lower jaw move sidewise or back and forth? Do the ridges on the molars run sidewise or lengthwise? Is a cow’s horn hollow? Does it have a bony core? (Fig. 344.) The permanent hollow horns of the cow and the solid deciduous horns of the deer are typical of the two kinds of horns possessed by ruminants. The prong-horned antelope (Fig. 391) of the United States, however, is an intermediate form, as its horns are hollow, but are shed each year. The hollow horns are a modification of hair. Do solid or hollow horns branch? Which are possessed by both sexes? Which are pointed? Which are better suited for fighting? Why would the deer have less need to fight than the cattle? Deer are polygamous, and the males use their horns mostly for fighting one another. The sharp hoofs of deer are also dangerous weapons. The white-tail deer (probably the same species as the Virginian red deer) is the most widely distributed of the American deer. It keeps to the lowlands, while the black-tailed deer prefers a hilly country. The moose, like the deer, browses on twigs and leaves. The elk, like cattle, eats grass. [Illustration: FIG. 392.—ROCKY MOUNTAIN SHEEP (_Ovis montana_). × ¹⁄₂₄. ] The native sheep of America is the big horn, or Rocky Mountain sheep (Fig. 392). The belief is false that they alight upon their horns when jumping down precipices. They post sentinels and are very wary. There is also a native goat, a white species, living high on the Rocky Mountains near the snow. They are rather stupid animals. The bison once roamed in herds of countless thousands, but, with the exception of a few protected in parks, it is now extinct. Its shaggy hide was useful to man in winter, so it has been well-nigh destroyed. For gain man is led to exterminate elephants, seals, rodents, armadillos, whales, birds, deer, mussels, lobsters, forests, etc. [Illustration: FIG. 393.—PECCARY (_Dicotyles torquatus_) of Texas and Mexico. × ¹⁄₁₂. ]