168 NATURAL HISTORY. 
chest of the Semnopitheci oil the one hand, and that of the lower four-footed animals on the other. 
It has good lungs and a strong heart, and the intestines, stomach, and liver do not occupy as much 
space relatively as in the genera of Monkeys already described. 
There is a singular approach in the conformation of the fore hand to the paw of the Carnivora 
and a great departure, so far as resemblance is concerned, from that of man in the Mandrill. It is 
produced by the relative length of the bones which unite those of the wrist to those of the fingers • 
for these so-called metacarpal bones, four in number, leaving out that of the thumb, are of the same 
length, and not unequal, as in the higher Apes and in man. Therefore, the middle finger of the 
Mandrill is not longer than the others, and hence the peculiarity of the hand as a whole. This is 
noticed in some Macaques to a certain extent. 
There is one anatomical peculiarity of the body which may also be noticed, as it relates to the 
movements of the animals, and their trotting and galloping on all-fours. The pieces of the back-bone 
in the neck have processes which project outwards (transverse processes), and in the Mandrill they 
have a triangular shape, and a ridge exists upon them, which is the representative of a very distinct 
piece of bone in most of the other Mammalia. Now, this structure appears to have to do with the 
attachment of a muscle which is also present in the Macaques, and which reaches from these transverse 
processes to the spine of the blade-bone (scapula), and its duty is probably to draw this bone forward, 
and to assist the fore limb in progression.* 
Most oi the peculiar muscular arrangements of the Cynomorpha previously described are repeated 
in the Mandrill ; but it has some which are of great interest. 
Thus, the great chest muscle (pectoralis major), which reaches 
in the higher Apes from the front of the chest to the upper 
arm-bone, is very large in the Mandrill, and is divided into 
three portions, anti the great air sac of the neck projects 
between them. There are also muscular fibres connected with 
the back, which assist the animal in pulling back its upper 
arm, and they give force not only to blows, scratchings, and 
tearings, but also velocity to the movements of the whole 
limb in moving along the ground. Strangely enough, there 
is a curious resemblance between the muscles of the thumb 
of the Mandrill and of the Orang-utan, two of them being 
united together, so as to give the thumb seven instead of 
eight ; the tendons of these muscles (the long adductor and 
the short extensor) remain, liow r ever, separate. This is a part 
of the anatomy which recalls the corresponding structures 
in the Carnivora, and indicates the restricted amount of 
movement in the thumb of the lower Apes and Monkeys. 
Having a good digestion, the Mandrill has a tolerably large liver, but it is separated into several 
lobes, or pieces, which are more in number than those of the other genera; but as it is partly 
insectivorous in its diet, there is no necessity for a very full-sized large intestine, and this is not 
furnished with the appendix noticed in the man-shaped Apes. 
Finally, as regards the skull, it may be said, that that of a large adult Mandrill is the strongest 
created ; so huge are the jaws, face, teeth, and crest-ridges, that one wonders where its brain can be 
put in life. The true brain -case is indeed small, and is encroached upon inside by the back of the 
orbits, whence the eye looks out under the “ beetle-brows.” 
The forehead bone is triangular-looking, and there is no ascending of the forehead, the bone being, 
as it were, crushed flat, so as to make a triangular space with the brows in front. Ridges exist on the 
sides of this space, and pass backwards to the occiput, where they meet side crests from the ear-bones. 
The occiput is stuck up in a singular manner, and the surface of the bone is strongly marked by the 
muscles which draw the head backwards. Of course the singular part of the skull is the huge ribbed 
prominence of the upper jaw-bone on the side of the nose, and the great upper canine teeth. 
SKI'LL OF THE MANDRILL. 
# The A cromio-trachelian. It does not exist in the Chimpanzees, 
