140 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



Na.- 



P.m 



Fin. 97. Skull and jaw of Diniclis syualidens, a primitive Machaerodont Felid from the Oligo- 

 cene of Colorado. Note the position of the carnassials ( /i 4 , ntj) in relation to the areas of insertion 

 of the muscles of mastication. The action of the lower teeth on the upper teeth is from behind 

 forward and upward, x y. After Matthew. 



Fio. 98. Inferior view of the skull of Pl<l' <">.' ! ucosh us, an ancestral Raccoon (Procyonid) 

 from the (Upper) White River Formation, Oligocene Colorado, showing the subsectorial modifi- 

 cation of j>4, the crushing character of -,/ji, ml, the absence of ntf. X {-. After Matthew. 



