430 Eaton — John Day F elided in Marsh Collection. 



incisors are preserved. While the immature develop- 

 ment of the skull admittedly detracts somewhat from its 

 value as a specific type, this deficiency is nearly compen- 

 sated by the fact that the teeth of the permanent set 

 exhibit practically no signs of wear, and therefore 

 present, so much the more clearly, their characteristic 

 form. 



The material is provisionally attributed to the upper 

 John Day because of the gray color of the ashy matrix, 

 which, although slightly tinged with green, can not be 

 described as bluish-green; but as this stratigraphic 

 reference is unsupported by field records or other data, 

 it should not be regarded as established beyond question. 



Fig. 1. 



Fig. 1, — Pogonodon serrulidens, sp. n<Xv. Holotype. X %• 



Dentition. — I 3 , C 1 , P 3 , M 1 . The upper canines are 

 compressed. The anterior margin of the right upper 

 canine, which is exposed to view for nearly half its 

 length, is sharper than in Nimravus, the serrated anterior 

 ridge following the actual anterior margin of the tooth 

 for a greater distance from the point than is the case in 

 Nimravus. P 2 is very small, practically vestigial, and, 

 single-rooted. P 3 is much smaller in proportion to P 4 

 than in Dinictis and Nimravus, in this respect nearly 

 resembling Pogonodon davisi. P 4 is without a positive 

 inner cusp (protocone), the inner root being small and 

 closely adpressed to the anterior root. It has a small 

 but definite anterior accessory cusp (parastyle) distinctly 

 separated from the sharp anterior margin of the para- 



