68 ANTHROPOID APES. 



is generally rounded off, but is sometimes rather 

 laterally compressed. 



The OS calcis of the foot is slender, curved out- 

 wards in the centre and inwards behind the astra- 

 galus. The head, with its cuneiform extremity, is 

 of a transverse oval shape, turned inwards. The 

 scaphoid bone, which is generally in connection with 

 this projection, takes the same direction towards the 

 inner side of the foot. This peculiar contortion 

 causes the tarsus of the gorilla to appear almost as 

 if it had been subjected to a deviation or fracture 

 of its longitudinal axis. 



In young and adult males, as well as in young 

 females, the structure of the bones is generally 

 less massive than in aged males. In the female 

 skeleton the strongly developed depressions and 

 ridges, especially in the bones of the extremities, 

 are absent. The head of the ulna is, for example, 

 less deeply set in the case of a female, and its pro- 

 jections are smaller than in the male animal. In 

 the female, also, the head of the radius is smaller, 

 and the triangular shape of its shaft is less strongly 

 marked. The pelvic bones of a female gorilla are 

 wider, flatter, and less concave on their very pro- 

 jecting inner surface. They diverge more widely 

 from each other, and this is also the case with the 

 tuberosities of the ischium. The pubic arch is less 

 depressed than in the male gorilla. Although the 

 spinous processes of the vertebra} attain to some 

 length and thickness, their development in the 

 female is not so great as it is in the male sex. 



The bony structure of the chimpanzee offers 



