334 



PALEONTOLOGY 



to the third premolar the teeth have a more or less trench- 

 ant crown. The back of the third premolar (p 3), and all 

 the fourth premolar (2?. 4), show the crushing form of 



crown ; the pat- 

 tern of which in 

 the true molars, 

 after the wearing 

 down of the first 

 sharp cusps, pro- 

 duces the double 

 crescentic lines of 

 enamel which are 

 now peculiar to 

 the Euminants 

 amongst hoofed 

 quadrupeds. The 

 first (p 1), second 

 (p 2), and third 

 (P 3) premolars, 

 have their crown 

 much extended 

 from before back- 

 wards, with three 

 progressively more 

 developed and 

 pointed compress- 

 ed cusps on the 

 same line : to 

 which is added, in 

 the upper jaw, an 

 inner ridge, de- 

 ^-""" ,/ veloped in the 



third premolar 

 (p 3) into an inner posterior cusp. The fourth premolar (p A 



