GENERAL EES CRIETI ON OF THE GORILLA. 
17 
another which is less prominent, and placed across the back of the skull, from the back of one ear to 
that of the other. The animal has the power of moving the flesh and skin which constitute the scalp 
freely forwards and backwards, so that when it is in a rage its scowl is made all the more threatening 
and ugly by its frowning and bringing down the hairy ridge close to above the eyes. The hazel eyes 
are large, and they are separated by a small prominent bridge belonging to the nose, the rest of 
which is broad and flattened out. The jaws project forwards, and are long and wide, the teeth being 
large and strong, and visible when uncovered by the fleshy and rather hairy lips. The ears are small 
for the size of the head, when they are compared with those of other Apes, and they as well as the 
skin of the face are naked and dark. 
Nature lias been kinder to the females so far as beauty is concerned, for they have less 
marked crests of hail*, 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 f 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 interest- 
ing manner. 
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 com- 
municating 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. 
There is another very strong bone connected with the skull, which feels like a ridge, passing 
backward from the eye to the ear ; and it has something to do with the other ridges, for the muscles 
which are attached to them, and which pass down to the lower jaw to give it great power of mastica- 
tion, are covered on the cheek by it. This cheek-bone forms a kind of arch, and gives the great 
breadth to the upper part of the face of the animal. 
In a front view of the skull of the male Gorilla the ridge or crest on the top of the head stands 
up like a little peak ; then over the eyes is the great brow ridge, which seems to press the upper part 
of the cavity for the eye (the orbit) flat, so that it is not round as in most animals, but rather scpiare 
in outline. These three sets of ridges, those of the upper and back part of the brain case, that of the 
