Vol. 5] 



Merriam. — John Day Camivora. 



33 



Oligobums differs in having four inferior premolars and two 

 molars instead of three premolars and three molars; in the ab- 

 sence of an anterior basal tubercle on P..; in the shorter heel of 

 Mj ; and in the greater width of M 2 . The metaconid of M, in 

 Oligobunis appears from Cope's figures to be considerably larger 

 than in Philotrox, and the anterior portion of the lower jaw is 

 more slender. 



The imperfectly known Hyaenocyon has apparently the same 

 number of inferior premolars as Philotrox, but in H. basilatus 

 they are somewhat heavier and the anterior basal tubercles are 

 much better developed. P 2 is markedly trilobate in this species, 

 but is without accessory tubercles in Philotrox. This tooth is 

 also relatively much smaller in Hyaenocyon. There is little cor- 

 respondence between the inferior dentition of Philotrox and the 

 dentition of //. seetorius in form and arrangement of the teeth. 

 The sectorial portion of the inferior carnassial of Philotrox is 

 exceedingly narrow antero-posteriorly compared with the fore 

 and aft diameter of the upper carnassial in H. seetorius. The 

 presence of the third lower molar in Philotrox indicates the ex- 

 istence of at least two molars in the upper series, while Cope 

 confidently states that there was but a single superior molar in 

 H. seetorius. 



The lower jaw of E)tliydrocyo)i is unfortunately even more 

 imperfectly known than that of Hyaenocyon. There are prob- 

 ably three inferior premolars in this genus, though P. is un- 

 known. The premolars are at least specifically distinguishable 

 from those of Philotrox, and P.. has no anterior basal tubercle. 

 The heel of M 1 in Enhydrocyon appears to be narrower poste- 

 riorly than in Philotrox, and has, according to Cope, 27 "an abso- 

 lutely median cutting edge." There is, however, a rudimentary 

 entoconid at the base of this cusp. The first tubercular is appar- 

 ently also rather of the laeinate type, possessing "a nearly me- 

 dian cusp in front, which is joined to the low one on the internal 

 border of the crown." It is not known whether M. t was present. 

 In the skull of Enhydrocyon the single pair of postparietal fora- 

 mina are larger but are apparently situated much as the poste- 



- ; E. D. Cope. Tertiary Vertebra ta, p. 938. Also, ibid, "The heel of the 

 sectorial is cutting, as in Temnocyon." . . . 



