Eaton — John Bay F el idee in Marsh Collection. 131 



cone by a narrow oblique cleft. This is a character which 

 the present species shares with Pogonodon davisi, but not 

 with P. plat y co pis, for according to Cope 9 the upper 

 sectorial of the latter species has no parastyle. The 

 paracone and metacone of P 4 are separated by a deep 

 notch much as in Dinictis and Nimravus j and judging 

 from the illustrations of Pogonodon davisi, as in that 

 species also. M 1 is small with much reduced inner lobe. 

 P 4 which is fortunately preserved in one of the mandib- 

 ular fragments, has a relatively greater transverse 

 breadth than I have observed in specimens of Nimravus. 

 In this greater breadth and in the extent and form of the 

 notch separating the posterior basal tubercle from the 

 principal cusp, this tooth closely resembles the P 4 of 

 Thorpe's Pogonodon cismontanus, Cat. No. 10053, 

 Y. P. M. 



The cutting edges of all the teeth, including even the 

 vestigial P 2 , are finely serrated. This condition would 

 facilitate the sectorial action of the teeth of a young 

 and comparatively weak animal. It would be of 

 progressively less advantage as the jaws and their mus- 

 cles acquired greater strength. By the time the animal 

 was fully adult, the serrations would probably be nearly 

 or quite worn away from all the cheek-teeth, while on the 

 canines, which because of their special function are less 

 subject to detrition, the serrations might be expected 

 to persist much longer. Sand and gritty substances 

 taken into the mouth with food are a constant cause of 

 dental detrition among the Carnivora, not excepting even 

 the cleanly Procyon lotor, and in view of the habit of some 

 recent large felines of crunching bones, 10 it is probable 

 that similar habits, acquired as the large extinct felines 

 approached maturity, would hasten the destruction of 

 the serrated sectorial edges. The resemblance of these 

 serrated teeth to small saws has suggested the specific 

 name, but it is not assumed that the cheek-teeth were 

 serrated only in this species, or indeed in this genus alone. 



One of the mandibular fragments supports a lower 

 permanent canine lacking the upper half of the crown. 



9 E. D. Cope, Eeport of the TJ. S.. Geol. Survev of the Territories, vol. 3, 

 981, 1884. 



10 Dr. W. Eeid -Blair, D. V. S., of the New York Zoological Park, informs 

 me that the lion, tiger, leopard and prima all use the large cheek-teeth for 

 this purpose. 



