The hairy coat of the gorilla consists of long, thick, straight or stiffly curved bristles, and also of shorter, thinner, and curled woolly hair. On the crown of the head the hair is somewhat stiff, from 12 to 20 mm. in length, and it becomes erect under the influence of anger. While the sides and fore-part of the chin are only clothed with short, stiff hairs, they grow thickly on the back part of the chin, like a beard or forelock. The hairs which turn outwards from the sides of the face and on the neck are 30 or more mm. in length. On the shoulders the hair is from 130 to 150 mm. long, hanging down on the upper arms and the back. In the middle of the upper arm the hair is from 50 to 70 mm. long, growing downwards as far as the bend of the elbow. At this point it generally begins to grow in an upward direction. On the back of the forearm it again grows downwards. In the middle of the forearm on its inner side, a parting of the hairs takes place, as one portion goes in front of the radius, while the other portion turns behind the ulna. On the back of the wrist a tuft of curved hair turns upwards; a middle tuft goes directly back; and the lower tuft, also curved, turns outwards. On the back of the hand the hairs turn towards the fingers. On the breast and belly the hairs are shorter and grow more sparsely. On the breast their direction is as a rule upwards and outwards. On the belly they converge from the ribs towards the centre and the navel. On the thighs the hairs are about 160 mm. long, and here, as on the lower part of the leg, they tend outwards, while on the back of the foot they grow towards 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.