NO. 8 UPPER EOCENE ARTIODACTYLA — GAZIN 87 



Leptomeryx does not appear to have originated in either Lepto- 

 tragidus or Leptoreodon but in some intermediate form possessing a 

 combination of characters in part resembUng one and in part the other. 

 The upper dentition of Leptomeryx most nearly resembles that of 

 Leptotragulus but the posterior portions of the lower premolars are 

 not readily reconciled. Likewise, the lower premolars of Leptoreodon 

 present an arrangement which is perhaps too differently specialized. 



LEPTOREODON MARSHI ^^ Wortman, 1898 

 Plate 18, figure 2 



Synonyms. — Merycodesmus gracilis Scott, 1898. 

 Camelomeryx longiceps Scott, 1898. 



Type. — Skull and both rami of mandible, A.M. No. 2064. 



Horizon and locality. — Uinta formation, near White River, Uinta 

 Basin, Utah. 



Discussion. — Leptoreodon marshi corresponds rather closely in size 

 to Leptotragulus proavus. The essential characteristics of the pre- 

 molars have been described above in comparisons on a generic level. 

 The molars may not be distinguishable from those in the larger species 

 of Leptotragidus. In general, they are relatively broad and highly 

 selenodont, lingually above and buccally below. The outer wall of 

 the upper teeth has prominent ribs and styles and a cingulum is well 

 developed. Internally, the cingulum may be heavy around the meta- 

 conule but is weaker or not defined lingual to the protocone. Between 

 these cusps lingually there is a distinct pillar or accessory cuspule 

 which, though variably developed, appears to be persistent. An equiva- 

 lent cuspule is present between protoconid and hypoconid below. The 

 lower molars, however, show less evidence of a cingulum, except on 

 the anterior and posterior faces. 



MEASUREMENTS IN MILLIMETERS OF DENTITIONS IN SPECIMENS OF 



Leptoreodon marshi 



Length of upper cheek tooth series, C (at 

 alveolus) -M^ inclusive 



Length of upper cheek tooth series, P*- 

 M*, inclusive 



Upper premolar series, P*-P*, inclusive.. 



*'' Also illustrated in Wortman, 189^ 

 pi. 3. figs. 15, 16. 



■*8 Type of Merycodesmus gracilis. 

 *^ Type of Camelomeryx longiceps. 



