2 26 Bulletin American Museum of Natural History. [Vol. XIX, 



a little more hypsodont, and the diastema both relatively and 

 absolutely less. It is throughout very suggestive of Poe- 



brotherium, much 

 more so than 

 ^\l [^^[^^^^^^^^^ either Proiylopus 



or Leptotragulus 



Fig. ig. Leptotragulus profectus. Type specimen, crown prOUVUS ITi the 

 view of teeth, natural size; molars 2 and 3 supplied from ^ ' 



another individual. details and Con- 



formation of the molar and premolar cusps. It shows much 

 less resemblance to Hypertragulus. Unfortunately no upper 

 teeth can with entire certainty be referred to our species. 

 Those which are doubtfully referred have the Leptomeryx- 

 Poehrotherium pattern, with strong mesostyle and a rib on 

 the external face of the anterior external crescent, but none 

 on the posterior; they are less extended transversely than 

 those of Leptomeryx, much more than those of Poebrotherium. 

 The upper molars of Hypertragulus are very easily distin- 

 guished by the entire absence of mesostyle and equal develop- 

 ment of the external ribs on anterior and posterior crescents. 

 No upper teeth of this pattern were found in the Pipestone 

 beds. The upper molars of Leptotragulus proavus are not 

 known. 



From the above facts I am inclined to believe that Lepto- 

 tragulus — this species at least — is more nearly related to 

 Poebrotherium than Professor Scott has supposed, and that 

 it has not much to do with Hypertragulus. It is probable in 

 either case that the caniniform tooth is the first premolar. 

 The species is really far nearer to Poebrotherium than is Pro- 

 tylopus petersoni; how much of the resemblance is due to 

 parallelism remains to be determined. 



Mr. Gidley discovered last summer in the Oreodon Beds of 

 South Dakota, a brachyodont camel, which may be a direct 

 descendant of this species. 



Measurements. 



Lower premolars, P2-P4 25 mm. 



Diastema in front of pz 10 



Last lower molar 15 



Lower molars, m^-J (from three specimens) 30 



