64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



HYOPSODUS WORTMANI Osborn 



Ten more specimens of Hyopsodus wortmani encountered in later 

 collections representing the La Barge fauna brings the total for 

 this species up to about 39, much less abundant than H., cf , mentalis. 

 Later collections from the New Fork horizon, however, show that 

 H. wortmani there outnumbers the larger form about 10 to 6 in the 

 small sample at hand. A single specimen, U.S.N.M. No. 22660, from 

 the collections of the Dad fauna is referred to this species ; all the 

 remaining specimens from the exposures beneath the Tipton tongue 

 south of Dad, Wyo., are of the very large species H. brozvni and 

 H. walcottianus. 



HYOPSODUS, cf. MENTALIS (Cope) 



Reference of Lostcabinian materials of Hyopsodus to the species 

 H. mentalis, while recognizing H. miticulus as the name for Gray 

 Bull materials, may well be perpetuating a taxonomic error. It is not 

 improbable that the Wyoming sequence of the forms concerned is 

 evolution in situ, whereas H. miticulus and H. mentalis are reported 

 to be contemporary in the Almagre of New Mexico, although only 

 H. mentalis seems persistent into the Largo beds, according to 

 Matthew's interpretation of the distribution of these species. 



Some 70 or more specimens of Hyopsodus in the collections repre- 

 senting the La Barge fauna are considered as possibly representing 

 H. mentalis, bringing the total for this locality to approximately 146. 

 Not previously recognized in the New Fork fauna, six specimens or 

 about a third of the Hyopsodus material from above the Tipton 

 tongue in the La Barge-Big Piney area may also be included in this 

 species. It is interesting to note, however, that of the materials I 

 have seen, none of the specimens representing Hyopsodus in the Dad 

 fauna, appears to be in this size range, although the horizon surely 

 corresponds closely in age to that of the La Barge fauna. 



HYOPSODUS BROWNI Loomis 



The species indicated here is the same as that for which Kelley and 

 Wood (1954, p. 355) have used the name Hyopsodus powellianus. 

 Unfortunately, the type oi H. powellianus is from an unknown hori- 

 zon in the Bighorn Basin, and while it may well have come from the 

 Lysite horizon, it could also be from the Lost Cabin level and repre- 

 sent a small individual of the form Matthew has called H. walcot- 

 tianus. Hyopsodus lemoinianus also has for its type a specimen from 

 an unknown horizon in the Bighorn Basin. H. lemoinianus has pri- 



