MAMMALIA QUADKUMANA. 535 



a hand nearly approaching to the human con- 

 struction. But the thumb is less developed, and 

 its muscles are much weaker than in man . 



The bones of the pelvis, as well as those of 

 the leg are elongated, for the purpose of giving 

 greater length to the muscles which are to move 

 their several parts ; by this means, although the 

 force with which they act may be somewhat les- 

 sened, yet the velocity of the motion they pro- 

 duce is increased in the same proportion. The 

 fibula is here a bone of more importance than in 

 quadrupeds ; for it performs a motion of rotation 

 round the tibia, analogous to that of the radius 

 upon the ulna, giving a great extent of action to 

 the foot, and converting the leg into an arm, as 

 we have already seen that the foot itself is trans- 

 formed into a hand. A small inclination is given 

 to the articulation of the tarsus with these last 

 mentioned bones, which imparts a degree of 

 twist to the feet, throwing the sole inwards, and 

 causing the monkey while walking to rest chiefly 

 on its outer edge. This seeming defect gives a 

 slight appearance of awkwardness to the gait ; 

 it is not, however, to be viewed as an imperfec- 

 tion, for it is evidently designed to assist the ani- 

 mal in climbing trees, which is its most usual 

 action, the oblique position of the foot enabling 

 it most eftectually to lay hold of the branches. 

 Monkeys are evidently not formed to excel in 

 swiftness ; for the heel, in these animals, presents 



