340 STEUCTUBE AND ADAPTATION OF TEETH 



As a result of these modifications, the facial 

 angle is greatly increased; and as the occipital 

 foramen is less obliquely situated, and advances 

 more toward the centre of the skull, the animal 

 is enabled occasionally to assume a nearly erect 

 position. 



The various species of orang-outang (Pithecus) 

 are all natives of the Indian Archipelago, and are 

 distinguished by their reddish-brown hair. In 

 these enormous apes, the teeth are all very large 

 and powerful ; the central incisors are remarkably 

 solid, and a transverse section of the crown shows 

 them to be square in form, the thickness being 

 nearly equal to the breadth ; the lateral incisors 

 are scarcely half the size of the centrals. The 

 diastema we noticed in the Carnivora is still 

 observable ; a space between the upper lateral 

 and canine permitting the lower canine to close 

 up in front of the upper ; a similar interval exist- 

 ing between the lower canine and first bicuspis, 

 allows the upper canine to overlap the lower 

 alveolar margin. 



The canines in the female are not more than 

 half the size of those teeth in the male, and rise 

 very little above the plane of the molar teeth. 

 The premolars or bicuspides are furnished in the 

 upper jaw with three roots, and in the lower with 

 two roots, corresponding in arrangement with 

 those of the true molars. 



Another very striking feature is observable on 



