184 



MAMMALIAN DENTITION 



and are frequently missing ; the second is lost in early adult 

 life. 



In the example figured one of the lower incisors is missing. 

 The incisors and canines do not differ in any important par- 

 ticular from those of other Carnivores. Of the premolars the 

 upper fourth calls for notice since it has lost its sectorial char- 

 acter and is a much simplified tooth. In the present specimen 



123 4 



the premolars still in place on the right side are 



and 



Fig. 65. — Dentition of American Black Bear (Ursus americanus, 9.7426-6). Ob- 

 seive that almost all trace is lost of sectorial feaLurcs in the teeth. Compare the molar 

 crowns with those of the Baboon (Fig. 43). 



on the left — - . The upper molars are elongated antero- 



11 4 



posteriorly, especially the second, with low, rounded cusps on 

 their crowns obviously very specialized, and the lower molars 

 are also greatly transformed for, although the first and second 

 show clearly their derivation from the typical form possessing 

 trigonid and talonid each with the full complement of cusps, 

 the third presents a crenated surface with no definite cusps. 



