802 TEETH OF ORANG AND CHIMPANZEE. 



malia that makes the nearest approach to that repre- 

 sented bj the genus liomo. 



Through a considerable part of the quadrumanous 

 series, e.g.^ in all the apes and monkeys of the Old World, 

 in all the genera, indeed, which are above the lemurs 

 (cat-monkeys and slow monkeys) of Madagascar, the same 

 number and kinds of teeth are present as in man; the 

 first deviation being the disproportionate size of the ca- 

 nines and the concomitant break, or " diastema," in the 

 dental series for the reception of their crowns when the 

 mouth is shut. This is manifested in both the chimpan- 

 zees and orangs, together with a sexual difference in the 

 proportions of the canine teeth. 



In that large ape of tropical Africa, called the "gorilla'' 

 {Troglodytes gorilla), which, in some important particulars, 

 more resembles man than does the smaller kind of chim- 

 panzee (Troglodytes niger), the dentition seems to approach 

 nearer to the carnivorous type, at least in the full-grown 

 male (see Fig. 50, p. 223). It is nevertheless strictly 

 qaadrumanous in its essential characters, as in the broad, 

 flat, tuberculate grinding surfaces of the molar teeth ; but 

 in the minor particulars in which it differs from the denti- 

 tion of the orang, it approaches nearer the human type. 

 In the upper jaw the middle incisors are smaller, the 

 lateral ones larger than those of the orang; they are thus 

 more nearly equal to each other; nevertheless, the pro- 

 portional superiority of the middle pair is much greater 

 than in man, and the proportional size of the four inci- 

 sors both to the entire skull and to the other teeth is 

 greater. Each iiicisor has a prominent posterior basal 

 ridge, and the outer angle of the lateral incisors, i 2, is 

 rounded off as in the orang. The incisors incline for- 

 wards from the vertical line as much as in the great 



