184 ANTHROPOID APES. 



served, extending from the neck of the tooth almost 

 to its point. The outer and inner sides of the 

 tooth meet in a sharp angle, somewhat convex in 

 front, and level or slightly concave behind. The 

 inner side is concave, and furnished, nearly in the 

 centre, with a deep longitudinal furrow. The lower 

 canine teeth of an aged male are shorter than the 

 upper, curved on their upper and outer surface, and 

 somewhat behind. Their form is also that of a 

 three-sided pyramid, rounded in front. The longi- 

 tudinal furrow which traverses their inner segment 

 is much shorter than that on the upper tooth. The 

 outer side is somewhat convex, and at the same time 

 somewhat retreating, and is provided on its posterior 

 segment with two longitudinal furrows, or more 

 rarely with one, reaching from the neck to about 

 the centre of the tooth. The inner side, like that 

 of the upper teeth, is somewhat concave. The lower 

 canine teeth project like pillars over the upper ones 

 (Figs. 15, 16). The canine teeth of a young male 

 gorilla are less sharp in their angles, although 

 they already present the form of a three-sided 

 pyramid. The canine teeth of the adult female 

 gorilla are much smaller than those of the adult 

 male, and are laterally more compressed. The 

 three-sided pyramidal form is only slightly marked. 

 The outer surface is convex and furnished with a 

 scarcely apparent central longitudinal ridge. On 

 the inner surface, or that which is turned to the 

 cavity of the mouth, there are from two to three 

 longitudinal furrows reaching from the neck to the 

 centre of the tooth. The lower teeth are of a 



