TEEIR ANATOMY. 
67 
which is called the coracoid, is more inclined downwards than in the Apes already described. Nov/, 
the blade-bone of the Chimpanzee and its coracoid are admirably adapted for climbing ; why are they 
not, therefore, exactly like those of the Orang, and vice versa ? This is not a difference produced by 
adaptation of means to ends, but one which relates to the origin of the two animals, and to those which 
preceded them. The same is the case in respect of the wrist of the Orang. It has one bone more than 
the Chimpanzee, which has the same number as in other Troglodytes, and in man also. This bone is 
fixed in between the two rows of the bones of the wrist, and is called the “ intermediate,” and is found 
in the Monkeys which are below the Orang in the animal scale. It is an offshoot of the scaphoid bone. 
Oddly enough, although the number of the ribs of the Troglodytes is thirteen, and probably in one 
of them there are fourteen, there are only twelve in the Orang ; and the breast-bone, which consists of a 
large upper bone and several smaller ones (united above and below to each other, in the Troglodytes), has 
these bones separate and halved, as it were, sideways in the Orang, resembling in it the condition of 
the bones of the immature man. In the Troglodytes the round top of the thigh-bone, where it fits 
into its socket, the hip, has a kind of rope-like ligament attaching the one bone to the other, but this does 
not exist in the Orang. The knee-cap is very small, and the heel-bone hardly projects backwards in 
the Orang, and the “ toe-thumb” sticks out at right angles from the foot, being about one-quarter of its 
length. The Orang is a great climber, and rarely, if ever, walks on its sole, which the Chimpanzee can 
do slightly. The general appearance and the nature of the movements of the foot of the Orang is that 
of a thin “ club foot.” All the turning-in of the bones of the foot in the Chimpanzee is exaggerated in 
the Orang, whose toe-thumbs are capable of great activity. Tame Orangs may be noticed to use the 
foot, which is longer than the lower leg, in climbing, as perfectly as the hand ; and it appears that the 
frequency of their movements of grasping, rather than of delicate prehension, tends to the last joint 
of the “toe-thumb” becoming small and losing its nail. 
A huge air-pouch is packed away in front of the windpipe, and amongst the muscles of the neck, 
as in the Apes already noticed, and it commences in the so-called ventricles of the larynx. Its 
extension amongst the upper muscles of the chest is most remarkable, for when full of air, these, 
being relaxed, it must blow out the upper part of the body and neck in a singular manner. 
One of the muscles of the chest, common to man and Apes, the great pectoral ( pectoralis major) 
— which hits already been noticed as springing from the ribs, the breast and collar-bone, and to be 
attached in front of the groove in the upper arm-bone — is not a continuous sheet of muscular fibre 
as in man, but is divided into a number of bundles, there being at least three great ones. Now, it 
is between these and in their intervals that the vast laryngeal air-pouch is found on the chest. Great 
as it is, however, it does not appear to have anything to do with the voice, except, perhaps, produce 
resonance during distension. 
The muscles of the hips, thigh, and leg-bones of the Orang cannot be distinguished generally from 
those of the Chimpanzee ; but it is evident that the position of some is such as to make straightening 
of the knee very difficult, and on the contrary, they assist jumping and climbing, or any movement in 
which it can be kept permanently bent. As it is most convenient for the foot of the Orang to be well 
expanded during climbing or holding on, and not for its bones to be too much forced together sideways, 
the animal is deficient in a muscle which exists in man,* and which stretches transversely across, 
between the ends of the metatarsal bones. In like manner the inability of the thumb to perform 
many separate actions is produced by the absence of the flexor muscle ; but there is a slip of a 
muscle whose tendon reaches the first joint, and its office is to oppose the thumb, not to the palm of 
the hand, but to the first joint of the second finger. This is a monkeyish peculiarity. 
The animal, using as it does its short toe-thumb for grasping forcibly, requires all the power 
possible to be exercised between its bones and those of the ankle. Hence it has a muscle which exists 
in the hand but not in the foot of man, and which, from its drawing the bones together, is called the 
opponens (of the great toe). This does not appear to exist in the Troglodytes. 
The other most important peculiarities of the muscles which relate to the greater but less inde- 
pendent movement of the toes and fingers, are the connection of the long flexor of the “toe- thumb” 
with the lower and outer part of the thigh-bone, and the possession of a complete set of deep extensor 
# The Transversus pedis. 
