Nature has been kinder to the females so far as beauty is concerned, for they have less marked crests of hair, smaller brows, and shorter side teeth, and therefore more amiable faces under all circumstances. Of course the outside appearance of the head has much to do with the skull beneath, and this has been very carefully studied by anatomists. As a whole, the skull of a full-grown male Gorilla is larger than that of a man, but it is lighter, although it appears to be more massive on account of its being marked by great bony ridges or crests, which correspond with the lines of hair on the top and back of the head, one being on the top like the crest of a helmet, and the other crossing the back and reaching the other so as to form a rude +T+ shape. Careful measurement proves the great size of the Gorilla’s skull as a whole, and that this is dependent mainly on the dimensions of the bones of the face, the cavity for the brain being smaller than that of man. But it does not appear at first very easy to explain how it is that this massive-looking skull should be lighter than that of man. A careful examination of the bones of the Gorilla’s skull explains the difficulty, and in a very interesting manner. [Illustration: SIDE VIEW OF THE SKULL OF GORILLA.] The massive and solid look is given to it by the crests or ridges beneath the hair already mentioned; they are of great use, for they give attachment to very powerful muscles, especially to those which move the lower jaw, and enable the teeth to bite forcibly. The surface of the bones of the head for a certain depth is solid enough, but below this solid layer there is a cellular arrangement consisting of a network of bone, with cavities communicating with each other with the internal parts of the ears and nose. Below this is solid bone again. So that there are three layers, and the central one gives lightness and strength to the whole; moreover, it protects the brain under the skull from receiving shocks during falls or blows by boughs. When the skull receives a sharp blow, for instance, in front or behind, or low down at the sides, the outer layer of solid bone is often cracked, and even forced in. If there were no cellular layer, the tender brain would be injured directly, but the network of bone and the large spaces amongst it take off the jar from that important organ, and suffer the outer layer to be pressed in without affecting the deeper structures. It must be a very hard blow that can press the cellular layer in sufficiently to break through the third layer, which is solid but thin. Very possibly the larger air spaces of the cellular layer assist the senses of hearing and of smelling also.