ANATOMICAL STKUCTURE OF ANTHROPOIB APES. 185 



three-sided, pyramidal form, presenting an interior, 

 posterior, and inner superficies. 



The pre-molars of an aged male gorilla are wide, 

 and are furnished with a large outer, and a smaller 

 inner, cusp. The three four-cusped upper molars 

 display a more regular and symmetrical arrange- 

 ment of their cusps than is the case with the 

 female, in which the position of the cusps is rather 

 variable. Except for the difference of size, the 

 relative conditions of these teeth are the same in 

 male and female. The first pointed lower pre- 

 molars are in the male of the form of a four-sided 

 pyramid, convex on the anterior and outer surface, 

 flat on the side directed to the cavity of the mouth, 

 and marked with furrows on the posterior surface. 

 The small second and lower pre-molars have two 

 anterior and one posterior cusp. The last is gene- 

 rally worn away at an early age. Each molar tooth 

 has two outer and two inner cusps, opposite to each 

 other, and one posterior cusp. We cannot here fail 

 to notice the likeness to the conditions of the human 

 teeth, a likeness which is still more striking in the 

 female. 



In the chimpanzee, also, the upper central 

 incisor teeth are broadly chisel-shaped, while the 

 upper and lower lateral incisors are smaller. In 

 the male there is often a considerable gap be- 

 tween these and the canine teeth. The latter 

 present the form of a three-sided pyramid, of which 

 the anterior edge is blunt and tends outwards, while 

 the posterior angle is sharp, scooped out in its 

 upper third, and terminating at the base of the 



