Vol. 5] 



Merriam. — John Day Carnivora. 



ment in platycopis, but judgment on this character should prob- 

 ably be suspended, as the frontal region of the type of platycopis 

 is imperfect. As far as I am aware, the character of the inner 

 tubercle of the upper sectorial in platycopis is unknown. M 1 in 

 platycopis is stated by Cope to be characterized by its great 

 transverse extent, while it is exceptionally narrow in davisi and 

 brachyops. 



From Pogonodon, brachyops it is distinguished by its rela- 

 tively much larger canine, smaller P\ narrower M 1 , less abbre- 

 viated muzzle, and higher sagittal crest. 



The species of the deinictid group in the John Day beds in- 

 clude two types. One is represented by Dcinictis cy clops, which 

 corresponds quite closely in nearly all of its characters to the 

 typical Dcinictis of the White River. The other group is repre- 

 sented by davisi, brachyops and platycopis. The second group 

 seems to belong pretty definitely with the deinicticls, but repre- 

 sents such a degree of advance away from the typical Dcinictis 

 that it becomes important to refer to it as a distinct division. 

 These species are characterized particularly by increase in the 

 size of the canines, though not to a great extent in the vertical 

 length, reduction of the anterior premolars, loss of INI. and of the 

 metaconid of M 1; and reduction of the inner lobe of M 1 in two 

 species. In the only species in which the inner side of the supe- 

 rior carnassial has been examined, the deuterocone is reduced. 

 In all three of the species the frontal region seems to be wide, 

 the temporal fossae are exceptionally large, and the auditory 

 meatus is appreciably narrowed by the posttympanic process. 

 The species thus grouped seem to resemble each other more 

 closely than they do other forms, and stand in decided contrast 

 in most characters to Dcinictis cy clops of the same beds. 



In order to express in the classification the relation of these 

 John Day species to each other and to the typical deinictids of 

 the Oligocene, it seems to me advisable to use the arrangement 

 proposed by Cope, and to separate platycopis, brachyops, and 

 davisi as the Pogonodon group, of at least subgeneric rank. 



Of the extremities of the Pogonodons very little is known, but 

 Cope has shown that the limbs were slender and the feet narrowed 

 as in the running types seen in Nimravus and Dcinictis. 



