16 2 
NATURAL HISTORY. 
wards, and not upwards and inwards as it does in the Gorilla. The forearm bones, longer than 
the arm-bone, are modified, and the most movable of them (the radius) is so much jointed to 
the arm-bone that the power of moving the lower part of the forearm upwards and downwards 
(of pronation and supination) is much diminished. There is the extra bone in the wrist, making 
nine, and one of the bones sticks out behind (pisiform), so as to form a kind of heel to the hand. 
The thumb is complete except in the Colobi, but it is short in proportion to the other fingers ; 
and in some the third and fourth fingers are equal in length, thus departing from the Ape, whose 
third finger is always longest, resembling rather that of beasts of prey. The blade-bone differs much 
from that of the Anthropomorpha, being longer and narrower, and the portion above its spine, 
instead of being large, as it is in such ponderous climbers, is small. All these arrangements relate to 
THE SKELETON OF THE MANDRILL. (From the Cyclopedia of Anatomy and Physiology.) 
the running on all-fours, the palms of the hands being applied to the ground. Moreover, in order that 
the hand should thus resemble a foot in its duties, some of its muscles simulate those of the foot and 
fore-leg. Thus a muscle -which extends the metacarpal bone of the thumb (the bone between the 
wrist and the thumb under “ the ball”), and keeps the thumb flat on the ground in running, and 
tends to pull it up, has a slip which is attached to the bone of the wrist, called trapezium, and -which 
is at the wrist end of the metacarpal bone. It extends the wrist as well as the thumb. How this is 
an arrangement seen in the foot, where a muscle extends the great toe’s metacarpal bone and the ankle 
bones also. In order to carry out this extension of the fingers, so as to prevent downward bending (or 
flexing), they have a complete double set of extensor muscles. 
All the Cynomorpha have the lifting muscle of the blade-bone ; and the muscle which pulls the 
elbow back and assists in climbing, both in the Gorilla and its fellows, is present (the slip from the 
back to the elbow, Bor so-epitrochle arts) . 
The nature of the spine and back-bone processes has been noticed in the Mandrill, but it is 
necessary to state that the hip and haunch-bones are not closed in behind by a distinct sacrum, as is 
the case in the Anthropomorpha. The arrangement in the Cynomorpha closely resembles that of the 
great beasts of prey, but the haunch-bones are turned out slightly so as to form a seat. There is 
considerable variation in the number of the bones in the back and tail. With regard to the hinder 
