ANATOMICAL STRUCTURE OF ANTHROPOID APES. 167 



found it to be bicipital in animals of this species. 

 The lower or hinder head issues, as in man, from 

 the coronoid process of the ulna. Both in the 

 gorilla and in the chimpanzee it extends far in a 

 downwards direction on the radius (Fig. 52). The 

 flexor carpi radialis starts in the chimpanzee with 

 one head from the inner condyle of the humerus, and 

 with the other from tlie radius. Bischoff describes 

 the structure of the long abductor of the thumb in 

 the orang, the baboon, the jpitliecia, and the hapale 

 as resembling that of man. But in the gorilla, the 

 chimpanzee, and the macaca the tendon divides into 

 two parts. Nor does one tendon belong, as in man, 

 to a short extensor of the thumb, but the latter is 

 wholly absent, and the division of the tendon only 

 implies a continued division of the attachment to 

 the trapezium, as well as to the metacarpal bones of 

 the thumb. This division of the tendon also occurs 

 in the gorilla, which likewise possesses a short ex- 

 tensor of the thumb. In this point, again, apes 

 display a greater likeness to one another than to man. 

 According to my own researches, the long abduc- 

 tor of the thumb in anthropoids forms a muscle not 

 more considerable than one in proximity with it, of 

 which the origin and more central direction recall 

 the short extensor of the human thumb. In all 

 four species I found that the abductor had two 

 tendons, and was attached to the trapezium. The 

 muscle in its vicinity is inserted above the base of 

 the first metacarpal bone. I have not been able to 

 discover an extra extensor of the thumb in the 

 gorilla. The question now arises what we should 



