Oligocene (White River) Felidce. 223 



This is the -first reference of Pogonodon to the Oligo- 

 cene of the Big- Badlands. The size is close to that of the 

 type of the genus, P. platycopis Cope, although in nearly 

 every dimension this specimen is slightly smaller. This 

 size difference is, however, to be expected, since Hoplo- 

 phoneus is largely restricted to the Great Plains region 

 and is generally smaller than Dinictis and Nimravus, char- 

 acteristic of the John Day fauna, to which P. platycopis 

 belongs. When Cope established the genus Pogonodon, 

 he recognized that it had characters referable to both 

 Hoplophoneus and Dinictis, both of which genera he also 

 founded. 



In most respects, Pogonodon resembles Dinictis more 

 closely than it does Nimravus, e. g., in the number of 

 teeth, configuration of horizontal rami, and position of 

 the mastoid. The coronoid process curves backward as 

 in Dinictis, and the masseteric fossa is triangular rather 

 than horizontally oval-shaped, and the carnassial notch 

 is deep. On the other hand, it resembles Hoplophoneus 

 in that it lacks M 2 , which Dinictis has, and yet it possesses 

 P 2 , a factor which removes it from Hoplophoneus toward 

 Dinictis. It differs from either Dinictis or Hoplophoneus 

 in that the sectorial is primitive, having no metaconid but 

 possessing a robust posterior heel with a grinding sur- 

 face, which is an unique character. The dental formula 

 is I 3 , Cj, P 3 , M x . The lateral angular process below the 

 anterior portion of the ramus is not so deep as in Hoplo- 

 phoneus, but corresponds more closely to Dinictis. The 

 chin is quite vertical and oblong-square as in Hoplophon- 

 eus. The canines are considerably larger than the third 

 incisors and are noticeably recurved. The incisors have 

 conic crowns. The inferior border of the mandibular 

 ramus, which underlies the cheek teeth, projects outward 

 and downward as in Hoplophoneus. The rami in gen- 

 eral are not so deep and are more robust than in 

 Nimravus. 



The writer's opinion is that the genus Pogonodon should 

 be restored to its former position as an independent 

 genus, or at least be considered as a subgenus, but with 

 its affinities clearly recognized. In 1910, Matthew, 14 in 

 a footnote, writes that he regards Pogonodon as a dis- 

 tinct subgenus, although in the same reference he includes 

 the then known species of this genus under Nimravus. 



14 W. D. Matthew, Bull. Am. Mus. Nat. Hist., vol. 28, 290. 



