ANATOMICAL STRUCTURE OF ANTHROPOID APES. 75 



jecting forwards, so as to form the cavity of the 

 abdomen, and, especially in the male sex, the anterior 

 spines of the ilium are more strongly developed, than 

 in the gorilla and orang-utan. The ischiatic tube- 

 rosities are of a spreading form, and diverge con- 

 siderably from each other. The pubic arch is deeply 

 hollowed, but the point of juncture is elevated. 

 As in the gorilla, the os sacrum resembles the 

 basis of a tail, but it is less developed and less 

 conical in form. 



In the chimpanzee, as well as in other anthropoids, 

 the coccyx gives altogether the impression of a 

 laterally compressed and rudimentary tail. This is 

 especially the case in young animals, in which the 

 coccyx always appears to be very narrow and. pro- 

 longed. In older animals this part gradually 

 W'idens, yet without losing its resemblance to a 

 rudimentary tail. 



The head of the femur resembles a section of a 

 sphere, of which the upper part is sometimes want- 

 ing. Its shaft, which is curved in front, is much 

 slenderer in the female than the male. The patella 

 is oval. In the tibia the narrow shaft is laterally 

 compressed, and bent inwards. The bones on the 

 inner side of the foot take a backward direction, 

 while those on the outer side, attached to the 

 fibula, turn outwards. 



In the ankle-joint the head of the astragalus is 

 much arched, and turned inwards. The scaphoid 

 bone is thick and deeply hollowed. The metatarsal 

 bones and phalanges have a considerable upward 

 convexity (Fig. 21). 



