4:36 Eaton — John Day Felidce in Marsh Collection. 



are not projected downward as in Hoplophoneus, but, 

 on the contrary, they rise considerably above the level 

 of a line adjoining the basion and prosthion. 



The two fragments of limb-bones, already mentioned, 

 have been compared with the corresponding parts of a 

 puma, Felis concolor, No. 015, Y. P. M., whose skull is 

 of almost exactly the same basal length as that of Pogono- 

 don serrulidens. The lengths of the ulnae of the two 

 animals can not be accurately compared, owing to the 

 imperfection of the fossil bone, but a well-marked 

 difference is presented in certain other proportions. 

 While the shaft of the ulna of the fossil species is the 

 more slender of the two, the diameter of its greater 

 sigmoid cavity, measured in the axial direction of the 

 limb, is considerably greater than in the recent species. 

 This indicates also a greater diameter of the trochlea 

 of the humerus. An analogous condition is presented 

 by the fragmentary metatarsal III, the proximal 

 articular surface of the bone being of almost exactly the 

 same extent as in the example of Felis concolor, while 

 the shaft of the fossil bone is slenderer. 



The present species is differentiated from Nimravus 

 and Hoplophoneus by the aggregate of the cranial and 

 dental characters, mentioned above, although, as might 

 be expected, not by each of these characters severally. 

 From Dinictis its differentiation is not so clearly denoted ; 

 yet in consideration of the low nasal region and the 

 relatively high parietal region, the reduction in size of 

 upper premolars 2 and 3, the reduction of the inner root 

 of P 4 with loss of protocone and addition of a well-marked 

 parastyle, I cannot consistently assign to it a place with 

 Dinictis felina, D. cyclops, D. squalidens, and D. pau- 

 cidens. Pogonodon alone of known genera seems open 

 to its reception, and the species to which, on the whole, 

 it shows the closest affinity is Merriam's Pogonodon 

 davisi. From this it is specifically distinguished by its 

 smaller size, relatively lower sagittal crest, more com- 

 pressed form of superior canines, 13 relatively greater 

 diameter of the postorbital constriction, relatively lower 

 and longer anterior zygomatic pedicle, and judging from 

 Merriam's illustration of the teeth, by the lesser prom- 



13 The canine alveoli of P. davisi, although they do not furnish an exact 

 basis for comparison, indicate a considerably greater transverse diameter. 



