26 
NATURAL HISTORY. 
attached to a flat surface on the blade-bone, but to a raised edge, which runs rather obliquely, and is 
called the spine of the bone. Now this muscle is of immense importance to the Gorilla, as may be 
imagined from the nature of its function or oflice : it is placed in the same position as in man, and 
between the same kind of bones, but the spine of the blade-bone is longer, broader, and more slantingly 
set in the Ape, so that extra strength and greater power are attained. 
TIils spine, or rather raised ridge, can be felt when we place the right hand over the left shoulder 
as far as possible, keeping the fingers between the neck and the end of the shoulder, and its slanting 
position can be traced best in the Gorilla ; and it may be mentioned, that in the Chimpanzee the 
direction is much more oblique. Above this spine of the blade-bone there is the upper part of the 
blade, arid it is covered with muscle, the space thus occupied being much larger in the Gorilla than in 
man. This muscle starts from this bone, to wldcli it is attached, and is united to the arm-bone, close 
to its joint with the blade-bone 3 it is larger in the Gorilla than in us, and one of its uses is to assist 
the deltoid just mentioned. 
There is rather an interesting arrangement in the old Gorillas, which is not found in the young or 
in man, and which appears to have to do with the power of this muscle and its prolonged action. The 
muscle is well supplied with blood, and the nerve which endows it with energy is particularly well 
prevented from being compressed during the movements of the muscles amongst which it runs, any 
compression being very injurious. The upper edge of the blade-bone is notched, and a dense tissue or 
b'gament stretches from one point of the notch to the opposite one, enclosing a small open space; 
now the nerve runs through this space, and is protected by the hard tissues of bone and ligament 
from the contraction of the soft muscles. I11 the old Gorilla a further protection is found in the 
presence of a li ttle projection of bone in this space, which acts as a greater preventer of pressure. 
After passing through this space the nerve enters the very substance of the muscle, and is 
distributed to its fibrils. 
The upper arm reaches down from the shoulder to the hips in the Gorilla, and its bone (os 
humerus , from the Latin) is strongly marked on its surface by roughnesses and ridges, to which the 
great muscles are attached In man the shape of the upper aim varies with the strength of the 
individual, but in the strongest man and in the most beautifully-shaped woman it has a swelling on 
the front, and tapers more or less towards the elbow. This is caused by the two-headed or biceps 
muscle, and by other muscles ending in tendons. But the Gorilla has a very shapeless upper aim ; 
it is, as it were, fat and round throughout, and very large above the elbow, and this is because of the 
size of the bone within, and on account of the muscles not tapering as they do in man, but being well 
developed right down to their ends. Hence, elegance of shape is sacrificed to extra muscular strength 
and size of bone. 
On looking at the arm-bone, which, being connected to the shoulder by a joint, has much to do 
with the act of climbing and striking, it will be noticed that it greatly resembles that of man in shape, 
but is longer, stouter, and clumsier. The joint is nearly in the shape of a rounded knob, and the corre- 
sponding depression or cup on the blade or shoulder-bone into which it fits, is an oval and concave 
surface, and they are kept close together by a kind of capsule which stretches from one bone to the other 
and encloses the joint. Perfect freedom of movement is insured by the bones being covered with 
glistening cartilages, and a delicate and moist membrane, and the motion from the shape of the 
apparatus is almost equal to that of a chandelier where there is what is called a cup-and-ball joint at 
the ceiling. It lias already been noticed that muscles are attached to the blade-bone and to the arm- 
bone below the joint, and that, this being movable, when they contract they move the arm, and the 
instance was given of the action of the deltoid muscle in raising the arm. In the Gorilla, this great 
muscle reaches lower down than in man, and there is a very strong mark in the shaft of the bone for its 
insertion. This gives the muscle greater play than in us, and enables it to lift, more slowly perhaps, 
but more efficiently, for the arm-bone between the joint and the place where the muscle is attached, is 
the long arm of a lever which is shorter in man. Below the globular head of the arm-bone is the shaft 
or cylindrical part of the bone which gives origin to the tliree-headed muscle called triceps, and is covered 
by the two-headed one (biceps) already mentioned, besides the deltoid. A deep groove allows one of the 
ends or heads of the biceps to pass along and slide over the joint and to reach the shoulder-blade. The 
shaft as a whole is more or less cylindrical, with a slight angular outline, the angles being projections of 
