ii MAN AND APES: TEETH. 115 



different from that described above (Fig. 18), the 

 canines are proportionally longer and more knife- 

 like; the anterior premolar in the lower jaw is 

 specially modified; the posterior molar of the lower 

 jaw is still larger and more complex than in the 

 Gorilla. 



Passing from the old-world Apes to those of 

 the new world, we meet with a change of much 

 greater importance than any of these. In such a 

 genus as Cebus, for example (Fig. 18), it will be 

 found that while in some secondary points, such 

 as the projection of the canines and the diastema, 

 the resemblance to the great ape is preserved; in 

 other and most important respects, the dentition 

 is extremely different. Instead of 20 teeth in the 

 milk set, there are 24: instead of 32 teeth in the 

 permanent set, there are 36, the false molars being 

 increased from eight to twelve. And in form, the 

 crowns of the molars are very unlike those of the 

 Gorilla, and cliff er far more widely from the human 

 pattern. 



The Marmosets, on the other hand, exhibit the 

 same number of teeth as Man and the Gorilla; but, 

 notwithstanding this, their dentition is very dif- 

 ferent, for they have four more false molars, like 

 the other American monkeys — but as they have 

 four fewer true molars, the total remains the same. 

 And passing from the American apes to the 

 Lemurs, the dentition becomes still more com- 

 pletely and essentially different from that of the 



