163 THE MAMMALIA OF THE DEEP KIVER BEDS. 



subsequent to the John Day and before the beginning of the Loup Fork is made 

 evident by such types as Ancliitherium, Blaslomeryx and Mastodon. 



BliASTOMERYX BOREALIS Cope. 



Proceedings Amer. Philos. 8oc., Vol. XVII, p. 222. 



This species is quite a large one, though somewhat smaller than the Palwomeryx 

 mognus and P. sansaniensis of Sansan. The skull is remarkable for the high and 

 narrow occiput, the upper portion of which is drawn out into a long, backwardly 

 projecting process composed of the parietals and supraoccipital, which is very 

 similar to the corresponding part of the occiput in the Oreodontidce. The horns are 

 trihedral at the base, gradually becoming rounded distally, and are of remarkable 

 length ; they are perfectly simple and unbranched, and in no specimen which I have 

 seen is there any trace of a burr. The surface of the horns is faintly marked by 

 vascular impressions, but is on the whole remarkably smooth, much more so than in 

 the antlers of the deer, and, as Cope has suggested, they were doubtless covei'ed with 

 skin throughout the lifetime of the animal. "At the base of the horn on each side 

 a wing-like expansion extends outward posterior to the orbit " (Cope). The upper 

 premolars, three in number, have the internal crescent or deuterocone complete ; 

 Pj_2 and pjs are massive and oval in section, while M is more extended transversely. 

 The molars are very brachyodont and are covered with very rugose and strongly 

 wrinkled enamel ; the internal crescents are complicated by accessory spurs, which 

 invade the valleys. The internal pillar or style is very variable, being sometimes 

 quite large, while in many specimens it is absent from one or other of the molars. 



Blastomeryx antilopinus Scott. 



Amer. Naturalist, 1893, p. 662. 



The type of this species is represented by a mutilated skull, three cervical ver- 

 tebras and various bones of the fore and hind limbs. It diners from the foregoing 

 species principally in size, being decidedly smaller; the median ribs of the external 

 crescents on the upper molars are less prominent. Other differences are to be ob- 

 served, but they are perhaps rather apparent than real and due to the imperfect con- 

 dition of the specimen. The muzzle is broken away, not only in this, but in all 

 known specimens of B. oorealis as well, and hence nothing is known as to the pres- 

 ence or absence of the upper canine. No isolated teeth have as yet been found in 

 the Deep River beds which can be regarded as the upper canines of Blastomeryx, 

 and Filhol reports the same fact with regard to the Palaiomeryx of Sansan (No. 13, 

 p. 251). On the other hand, Fraas (ISTo. 16, p. 38) refers the muntjak-like canines 



