NO. 8 MAMMALIAN FAUNA, BADVVATER AREA — GAZIN I7 



Scott's generic comparisons were made largely with Hyrachyus, 

 from which it clearly differs. I am convinced, however, that a distinctly 

 closer relationship to Hclaletes is indicated. The Badwater, Sage 

 Creek, and Washakie materials together provide the evidence showing 

 the sequence from Bridgerian Hclaletes through Uintan Desmato- 

 therimn to Oligocene Colodon. As a consequence, Desmatotherium 

 should be included in the Helaletidae, as Simpson (1945) has in- 

 dicated, not with Hyrachyus as Peterson (1919) placed it. On the 

 other hand, the subfamily separation of the Colodontinae from the 

 Helaletinae made by Wortman and Earle (1893), which Simpson has 

 preserved, cannot now be reconciled with the sequential arrangement 

 indicated above. 



DESMATOTHERIUM WOODI,e new species 

 Plate 2, figure 4 



Type.— Right maxilla with P3-I\P (P* incomplete), U.S.N.M. No. 

 20200. 



Horizon and locality. — Hendry Ranch member of Tepee Trail for- 

 mation on south side of Badwater Creek, SW cor., SE^ sec. 14, 

 T. 39 N., R. 89 W., Wind River Basin, Wyo. 



Specific characters. — Upper molar teeth approximately 20 percent 

 smaller than in Desmatotherium guyotii Scott or Desmatotherium kayi 

 Hough. Upper premolars smaller than in these species but relative 

 size intermediate between them and closer to D. guyotii. 



Discussion. — Four incomplete upper dentitions and a number of iso- 

 lated teeth, including some from the lower series, all from the Bad- 

 water Creek localities, represent the species D. zvoodi. Two of these, 

 part of the type and two upper premolars (part of U.S.N.M. No. 

 20202) were figured by Hough (1955, pi. 8, figs. 6 and 9) as material 

 referred to the Sage Creek species D. kayi. I have examined all the 

 Sage Creek specimens together with the Badwater material and find 

 there is no overlap in observed size range for each. The type of the 

 Sage Creek species is nearly 20 percent larger than that of the Bad- 

 water form. D. kayi was described as close in size to D. "guyotii" 

 but with smaller premolars. The premolars of D. zvoodi are a little 

 smaller than in D. kayi, but the ratio of their size to that of the molars 

 is more nearly as in £>. guyotii. 



The principal feature of the upper dentition of Desmatotherium, 

 distinguishing it from Hyrachyus, is the more progressive condition 

 of the premolars. The divided lingual portion of P^ and P* gives these 



" Named for H. E. Wood, II, in appreciation of his work on the Plyrachyidae. 



