374 ' Contributions to the 



Traill and Vrolik, but separately in the Gorillas of Wy- 

 man and Duvernoy, and in Owen's Orang. When on all- 

 fours, these last three muscles would also help retract the 

 leg ; in a Cynocephalus the Biceps was also attached 

 above the joint to the patella, and in the Dog, where the 

 motion is simple retraction of the whole limb, the Semi- 

 membranosus also is inserted into the patella, thus giv- 

 ing a broader attachment, when the separate flexion of the 

 limb below the joint is not required. Like the Glutcei, 

 these three muscles also serve to support the trunk on the 

 legs in one direction, while the Gracilis and Sartorius an- 

 tagonize them in front ; their great size causes me to think^ 

 as in the case of the Glutcei, that if the trunk could be 

 balanced they would be able to maintain it erect, though 

 probably with not so much steadiness, on account of the 

 heaviest part of the body being so far above the pelvis, 

 and not in and about it as in man. The Popliteus is not 

 constant ; in this individual I think it was rather thicker 

 than in man, but I did not find the cartilaginous nodule in 

 the external lateral ligament where the muscle arises. 

 Traill and Tyson could not find the muscle, but it was 

 present in Vrolik's Chimpanzee, and in the Gorillas of 

 Wyman and Duvernoy. Its action as a rotator inward 

 would be balanced by the short head of the Biceps, which 

 rotates outward. 



■ Gastrocnemius and Soleus. These are much thinner than 

 in man, but continue fleshy to their insertion ; the latter 

 has but one, the external head, as is generally the case in 

 the Quadrumana. The two unite at about two thirds 

 way down from the origins ; tlie place of this union varies 

 in different species, and often considerably in individuals 

 of the same species; I do not see that the place of union, 

 or the absence of the internal head of the Soleus, would 

 have much effect upon the motions of the foot. 



Plantaris. This was absent on the left side, and very 



