NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 2/ 



the basis of them that a tentative separation may be made. The greater 

 development of the vestigial hypocone on M^ and the lesser develop- 

 ment of the metaconid on P4 are not significant. 



There is no certain indication on the specimen label of the type of 

 B. elegans as to the horizon of the Uinta in which it was found, 

 except that it came from near the White River. Carnegie Museum 

 No. 2951, referred to B. elegans, has the information "Uinta B, 

 Wagonhound, White River, near Ouray, Utah," on the label ac- 

 companying it, so that so far only Uinta B has been demonstrated 

 for this species. 



Genus HYLOMERYX Peterson, 19 19 



Synonym"?. — Sphenomeryx Peterson, 1919. 



Type. — Hylomeryx annectens Peterson, 191 9. 



Discussion. — The genus Hylomeryx, the second dichobunid to be 

 named from the Uinta, appears to be clearly distinct from Bunomeryx 

 and, although contemporary with the latter, it is more like Homacodon 

 in many respects. The outer cusps of the upper molars are, for the 

 most part, rather more conically bunodont than in Bunomeryx, re- 

 sembling Homacodon. Also, as in Homacodon, the hypocone is a 

 well-developed, circular cone on M^ and M^ and but a very slight 

 expression of the cingulum on M^. The mesostyle is very weak or 

 in an incipient stage, intermediate between Homacodon and Buno- 

 meryx. The protoconule, however, is rather dififerent from both in 

 that it seems scarcely defined on the protoloph of M- and M^. It is 

 more distinctive on M^. 



The premolar teeth, both upper and lower, are relatively large and 

 robust in comparison with those in species of Bunomeryx. Moreover, 

 small diastemata may separate P^ and P2 from the adjacent premolars. 

 In the lower premolar series, P4 has a parastylid and metaconid, but 

 the latter may be weak or blunt in the Uinta B stage to somewhat 

 inflated in the Uinta C stage. 



The lower molar teeth are not readily distinguished from those of 

 Bunomeryx, although in the type of Hylomeryx annectens the proto- 

 conid and hypoconid would appear to be a little less crescentic. 



Sphenomeryx was defined by Peterson as distinct from Hylomeryx 

 principally on the absence of a hypocone (posterointernal cusp) on 

 M^ and the weakness of the deuterocone on P^. As far as M^ is 

 concerned, this appears to have been a misinterpretation. M^ is rather 

 well worn but under the microscope it is clear, from the enamel con- 

 struction midway on the metaloph, lingual to the metaconule, that the 



