thighs the hairs are about one hundred and sixty millimetres long, and here, as on the lower part of the leg, they tend outward, while on the back of the foot they grow toward the toes. On the back, shoulders, and on the thigh and leg, the bristles are slightly curved. This quality increases the general impression of shagginess and fleeciness which is produced by the hairy coat of these creatures. The woolly hair does not grow very thick, and is not much matted.
The color of the hair not only differs on different parts of the body, but also in different individuals. On the crown of the head it is of a reddish-brown, or rarely of a decided brown or black. The hairs in this region are sometimes dun-colored at the root, grayish-white in the center, and brownish-red, shading into the dark-brown tip. The hair on the lips is sometimes of a blackish-brown, sometimes whitish, or both colors are found together. The hair growing at the sides of the face is gray below, dark brown or almost black above. On the neck and shoulders the hair is of a gray color at the root, and gradually becomes lighter toward the tip. In the center it is brown, shading into a lighter color at either end; but this ringed form of color is not universal. The tips of the hair are dark, sometimes brown or reddish. The hair on the back, on the upper arms and thighs, is whitish or light gray for half its length, with a blackish-brown ring toward the tip, which is of a dark-gray color. Many of these hairs on the back have two brown rings on them. The forearms, hands, shanks, and feet are covered with hairs which are gray at the root, brownish gray, dark brown, or black at the tip. Round the posteriors there is a circle of white, gray, or brownish-yellow hairs, from ten to twenty millimetres in length. In both sexes variations from the color of the coat here described are not rare. It has been already observed that the brownish-red color of the hair on the head is sometimes exchanged for another shade. In many individuals the neck, shoulders, and back are of a dark gray, brown, or even black color. In others the forearms, hands, shanks, and feet are covered, like the rest of the body, with gray and brown hair intermingled.
The second species of anthropoid apes is the chimpanzee. In this case also we must consider successively the aged and young male, and the aged and young female animals.
The full-grown chimpanzee is smaller than the adult gorilla. In this species also the male is larger than the female. The chimpanzee is, speaking generally, of a slighter build than the gorilla.
The head of the aged male chimpanzee fundamentally differs from that of the aged male gorilla, since the skull of the former has a depressed crown, and the transverse occipital ridge is only faintly indicated. Since the orbits are also less strongly developed than in the aged male gorilla, and the spinous processes of the cervical vertebræ do not assume the same elevated form which is characteristic of the latter species, the countenance of the chimpanzee is not of a square
