Page:Popular Science Monthly Volume 28.djvu/760

740 width in different individuals, and often terminates on its inner edge in the projecting peaked excrescence described by Darwin, of which I shall have more to say presently. The anti-helix, tragus, and antitragus, and the cleft which lies between these two latter parts (incisura inter tragica) are generally fully developed; the lobule is more rarely present. Individual variations in the special structure of these parts may frequently be observed.

The strong trapezoid muscles are prominent on the neck, and when the head is stretched they stand out like pillars on the sides of the neck. Owing to the great development of the spinous processes of the cervical vertebrae, and of the muscles attached to them, and to the occipital bones of the skull, the neck is very powerful, almost like that of a bull. The shoulders are remarkable for their breadth, and the pectoral muscles for their large size.

On the upper and forearms the plastic form of the strongly developed flexor and extensor muscles is very apparent, testifying to the enormous strength of the upper extremities. The hands are large, and very wide, with short, thick fingers. The thumb, of which the extremity takes a conical form, is short, extending little beyond the middle of the second metacarpal bone. The extremities of the otherwise broad fingers are somewhat laterally compressed. The fore-finger is not materially shorter than the middle finger. The third finger is sometimes shorter than, sometimes of the same length as, the first, and the fourth is decidedly shorter. The back of the wrist is covered with deep oblique folds. A net-work of wrinkles, oblique or curved, also covers the skin on the back of the fingers, on which there are callosities up to the first joint. The gorilla closes the fingers when going on all fours, and turns the back of the hand on the ground, thus producing this thickening of the upper skin on the joints. Callosities of the same nature, although not so extensive, are not rare on the second finger joints. The palm of the hand is covered with a hard, horny skin, generally beset with warts, especially at the roots of the fingers. In spite of the blackness of the skin which covers them, these characteristics are still apparent.

The fingers are united by a strong web, reminding us of the membrane found on the otter and other web-footed animals, and reaching nearly to the first finger-joint. A thick coat of hair extends to the root of the fingers, although on the backs of the fingers there are only a few isolated hairs.

The trunk of the body of a gorilla, seen from behind, somewhat