246 



MAMMALIAN DENTITION 



teeth more vertically placed than in the adult, obviously a 

 surviving ancestral character. The canines more triangular 

 in the Chimpanzee and Gibbon than in ourselves are more 

 pointed in the Gorilla and the Orang. The first upper milk 

 molar is bicuspid and plainly triangular in the Gibbon and 

 Gorilla but shows a tendency to anteroposterior extension of 

 the palatal cusp in the other two great Anthropoids. The first 

 lower milk molar presents a large pointed cusp with a tiny 

 subsidiary one on its lingual aspect and a low and ill-developed 



Fig. 88. — Deciduous dentition of Chimpanzee (Pan sp., 9.88-11). 



heel behind in the Gibbon, Gorilla and Orang but in the Chim- 

 panzee this tooth approximates the human form, resembles in- 

 deed the Predmost type somewhat for the inner cusp is larger 

 and the heel is well developed and presents two cusps as in 

 ourselves (Fig. 88). The second upper molar is a typical tritu- 

 bercular tooth with a hypocone in all Anthropoids but in the 

 Chimpanzee and Orang the cusps are Ioav and even indefinite 

 and secondary erenations appear as in Man. The second lower 

 molar in the Gibbon presents primitive Anthropoid characters. 



