Comparative Myology of the Chimpanzee. 373 



the characters which gave them their names in Human 

 Anatomy. The reverse is the case in the leg of the com- 

 mon Quadruped, the Dog or the Cat ; in them the move- 

 ments are simply forward and back, quick and forcible, 

 but limited ; the muscles therefore are very thick and 

 strong, but short, and the limbs are sharply bent at the 

 joints. But this mass of muscle about the limb would be 

 wholly inconsistent with the motions of the prehensile foot 

 of the ape, or even a baboon, in whom tiierefore the mus- 

 cles are comparatively long and slender. The limbs of 

 the Quadrumana are also projected further from the trunk 

 than in the lower animals. In man the leg can be rotated at 

 the knee only in a state of semi-flexion ; this is the constant 

 attitude of the ape's leg, and the rotation is very free. 

 The short head of the Biceps would act as an external 

 rotator in the Anthropoids, but in the Mandrill I do not 

 think it exists, and in Quadrupeds generally it is want- 

 ing as such, though there is sometimes a slender slip from 

 the pelvis. 



Sartorius. Very long, from the great height of the 

 ilium ; it is inserted by a very short, fascia-like tendon 

 on the front of the tibia, at least one third from the knee, 

 over the Gracilis. The Gracilis is proportionally much 

 thicker and stronger than in man. 



Semi-membranosus. Tendon of origin long, that of in- 

 sertion shorter, but attached as in man. The tendon of the 

 Semi-tendinusHS joins that of the Gracilis, and is inserted 

 beneath it. Biceps. The long or ischiatic head is pro- 

 portionally smaller than in man, and absolutely smaller 

 than the Gracilis and Semi-tendinosus. The short head 

 arises as in man, and joins the other at the knee, forming 

 a very strong fascia which extends over the fibula nearly 

 to the ankle, the tendon of the long head sending a strong 

 prolongation to the outer tuberosity, as in man. The two 

 heads were inserted thus together in the Chimpanzees of 



