ANATOMICAL STRUCTURE OF ANTHROPOID APES. l7o 



tibia, just below the internal tuberosity, but it is 

 inserted much lower clown on this surface. In the 

 gorilla it has a tricipital attachment, one to the 

 deep fascia of the thigh, and two others to the in- 

 ternal border of the tibia. In the chimpanzee and 

 the gibbon the muscle extends equally low down. 

 In the orang it does not go so far, but the gracilis 

 and semi-tendinosus are in the same relative position. 

 The biceps of the femur is very apparent in the 

 orang ; its long head divides in two parts, of which 

 the lower is inserted in the fibula, and is here united 

 with the short head. 



Bischoff at first denied the existence of the 

 plantaris in the chimpanzee, and Briihl had pre- 

 viously done the same, but it is as normally present 

 in that animal as in man, in whom also it is some- 

 times absent. I, however, as well as other observers, 

 have failed to discover it in the gorilla, orang, and 

 gibbon. The popliteus is developed in every in- 

 stance. The tibio-fibular muscle (Musculus peroneo- 

 tihialis), covered by the popliteus, of which the 

 existence was ascertained by Gruber, has not been 

 observed by me in any of the anthropoids, with the 

 exception of the chimpanzee. But it was very 

 apparent in a red sea-cat monkey [Gercopithecus ruber). 



The gastrocnemius, which is easily separable into 

 two heads, and the peroneal muscles have not 

 the same relative width in anthropoids and man, 

 since in the former case the calf of the lower limb 

 is small, and it lacks the pleasing roundness which 

 characterizes this part of the human structure. 

 These muscles, especially in the orang and gibbon, 



