NO. I LOWER EOCENE MAMMALIAN FAUNAS GAZIN 65 



ority over H. powellianus, and while Matthew placed it in synonymy 

 with H. nientalis, it seems to be nearly or quite outside the observed 

 range for this species in the Wind River Lost Cabin and at about the 

 upper limit in the La Barge fauna. It certainly falls near the mean 

 for the Cottonwood Draw Lysite specimens called H. powellianus. 

 Nevertheless, in view of the possible confusion at certain levels, 

 probably H. hrowni is the least questionable designation. 



In addition to the specimens from near Knight Station in the 

 Fossil Basin that were described as belonging to this species in 1952, 

 I refer also a maxilla with part of M^ and M^ from high on the 

 southwest slope of Fossil Butte, in the deeper red beds just beneath 

 the Green River, and a lower jaw with Mg and part of M3 from the 

 saddle on the north side of Fossil Butte in the Fossil Basin. 



This large species is evidently not represented in the rather abun- 

 dant Hyopsodus specimens from below the Fontenelle or Tipton 

 tongue in the La Barge-Big Piney area. A single specimen (U.S.N.M. 

 No. 2266y), however, collected by N. C. Privrasky of the U. S. 

 Geological Survey, from a locality he regarded as near the base of 

 the Knight in this area, is much larger than any of the Hyopsodus, 

 cf. mentalis material and may tentatively be referred to H. hrowni. 

 In the Dad fauna, on the other hand, associated with Lamhdotherium, 

 most of the specimens of Hyopsodus at hand conform to the size 

 range of H. hrowni. The remaining specimens are quite outside the 

 range and may be included in small H. wortmani or very large H. 

 walcottianus. Also, above the Tipton tongue of this area, in the 

 Cathedral Bluffs member, Morris (1954, p. 197) has listed Hyopsodus 

 paulus. These specimens, consisting of a P*, an upper molar, and an 

 M3 are of a larger species than H. paulus and may tentatively be 

 referred also to H. hrowni. Their size would not warrant recognizing 

 H. walcottianus in the Cathedral Bluffs fauna. 



HYOPSODUS, cf. WALCOTTIANUS Matthew 



Material from the Knight beds that may appropriately be referred 

 to very large, but rare, Hyopsodus zvalcottianus has been found at 

 localities near Dad, Wyo. A lower jaw with incomplete M2 and M3 

 (U.S.N.M. No. 22663), a maxilla with M^ and M^ (U. of Calif. No. 

 43592) and an isolated M^ in the National Museum collection from 

 the Knight beneath the Tipton tongue along the escarpment south of 

 Dad appear much too large to be included with the contemporary 

 materials regarded as representing H. hrowni. Also, a single lower 

 jaw with P4 and Mi (U.S.N.M. No. 22669) from the New Fork 



