Morphology. 93 
their crowns. Indeed, in this respect it would seem 
that even in the anthropoid apes there is the be- 
ginnirg of a tendency to degeneration of the molat 
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- 
or 
Yom | nN \ WN 
OH GORILLA. wansize ORANG. KAN, 
| 
Fic. 24.—Molar teeth of lower jaw in Gorilla, Orang, and Man. 
Drawn from nature, nat. size (A. A/us, 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 
