CHAP. Vl] THE DENTAL SYSTEM OF THE PRIMATES 



249 



than does that of any cither Primate. Shortening of the maxillae has 

 evidently to be recognized, and the crowns of the premolar teeth, when com- 

 pared with those of Gorilla, are much reduced in the sagittal direction. 

 These teeth bear outer and inner cusps, while as regards roots a difference 

 may obtain, the first premolar tooth possessing three roots, the second tooth 

 having only two. 



The molars present a crown of equilateral proportions, the third tooth 

 being degenerate both in size and in the reduction of the posterior cusps, 



Fig. 176. 



Fig. 177. 



Fig. 178. 



Fig. 179. 



Fig. 176. Right upper canine and post-canine teeth of a Chimpanzee (ad. <? 

 W. L. H. D. priv. coll.). 



Fig. 177. Left lower canine and post-canine teeth of a Chimpanzee (ad. a 

 W. L. H. D. priv. coll.). 



Fig. 178. Right upper canine and post-canine teeth of an aboriginal native of 

 Australia. (Mus. Anat. Cant.) 



Fig. 179. Left lower canine and post-canine teeth of an aboriginal native of 

 Australia. (Mus. Anat. Cant.) 



of which the postero-external may be more affected than the postero-internal 

 cusp. (Thus confirmation of the statement to which reference has been 

 made already, is provided by one of the Simiidae only.) The other molar 

 teeth bear four cusps, viz., an anterior and a posterior pair, the characteristic 

 oblique ridge being present as in the other Simiidae. And it is to be 

 remarked that crenation is often distinct, though less characteristic of the 

 Chimpanzee than of the Orang-utan. In the mandible, the premolar teeth 

 are less like the corresponding human teeth than when the comparison is 

 made with teeth of the upper series. For in the mandible the characters 



