THE TEETH OF THE HIGHER APES AND MAN 183 



Primates, especially the Lemurs and Platyrrhines, 

 having the incisors of nearly the same width, and 

 the difference becomes apparent as the advance 

 is made from the lowest to the highest forms. 



The great canines stand out at the corners, and 

 are large and trenchant like those of the Baboons, 

 and there is still a large diastema in front of the 

 upper canine into which the lower one closes. . 



The premolars are of the bicuspid type, but 

 are. coarse and large, with strong, high, sharp 

 cusps. They are implanted by three roots above 

 and two below, just like the true molars and like 

 the lower Primates. The molar teeth are large, 

 square, and coarse, and increase in size from front 

 to back, the reverse being the rule in man. They 

 are of the distinctly human pattern, — quadrituber- 

 cular above, quinquitubercular below. 



The teeth of the Apes resemble those of man 

 in various degrees, but there are conspicuous dif- 

 ferences which can best be tabulated as follows : 



(a) Relatively to the size of the cranium, the 

 jaws and the teeth are very large and prominent 

 in the Apes. Hence they are very prognathous, 

 and the facial angle is low. In man, on the con- 

 trary, the jaws are much reduced, the cranium is 

 enlarged and brought forward, and the facial 

 angle is nearly vertical. 



(b) The dental arch is a long parallelogram in 

 the Apes, like the lower mammals. In man the 



