Morphology. 



93 



their crowns. Indeed, in this respect it would seem 

 that even in the anthropoid apes there is the be- 

 ginning of a tendency to degeneration of the molai 

 teeth from behind forwards. For if we compare the 

 three molars in the lower jaw of the gorilla, orang, 

 and chimpanzee, we find that the gorilla has five well- 



N AT. SIZE 



FlG. 24. Molar teeth of lower jaw in Gorilla, Orang, and Man. 

 Drawn from nature, nat. size (2?. Mus. Coll. Surg.\ 



marked cusps on all three of them ; but that in the 

 orang the cusps are not so pronounced, while in the 

 chimpanzee there are only four of them on the third 

 molar. Now in man it is only the first of these three 

 teeth which normally presents five cusps, both the 

 others presenting only four. So that, comparing all 



