312 THE HIND FOOT OR PES. [chap. 



in the same plane as the other toes, and cannot be freely 

 separated from, or opposed to, them. There are no supple- 

 mentary tarsal bones, and sesamoids are developed under 

 the metatarso-phalangeal joint of the hallux only. The 

 phalanges are much smaller, shorter, and more compressed 

 than are those of the manus. The ungual phalanges are 

 very small, depressed, and somewhat spatulate. 



The ])rincipal distinction of the foot of the Simiina from 

 that of Man is that it is more or less modified into a grasping 

 organ. The tarsal and metatarsal bones and phalanges are 

 the same in number and relative position, but the articular 

 surface of the internal cuneiform for the hallux is saddle- 

 shaped, and is directed obliquely towards the inner or 

 tibial side of the foot. The consequence is that the hallux 

 is not only somewhat separated from the other digits, but 

 is also set in a different plane, so that when it is flexed it 

 turns towards the sole of the foot, and becomes opposed to 

 the others, much as the thumb does in the human hand. 

 It is this peculiarity of the pes which has given rise to the 

 term quadn/nianous, or " four-handed," often applied to this 

 group of animals. 



The hallux is usually relatively shorter than it is in Man. 

 In the Orang {SiJ/iia satyrus) it is particularly short, and 

 often wants the terminal phalanx, while the metatarsals and 

 the phalanges of the other digits are long and curved, the 

 proportions of the three segments of the foot being exactly 

 the reverse of those of Man, as the tarsal segment is 

 shortest, and the phalangeal the longest. 



The form of the articular surface of the astragalus, and 

 especially the free mobility of the navicular and cuboid 

 bones on the astragalus and calcaneum, cause the foot of 

 the Orang to be set very obliquely on the leg, so that when 

 placed on a level surface the fibular border only rests on the 



