NO. I LOWER EOCENE MAMMALIAN FAUNAS — GAZIN 57 



and in comparison with the type of D. protenus the La Barge form 

 exhibits distinctly larger teeth and much deeper jaws. 



Among the newer collections from the New Fork tongue there is, 

 in addition to several isolated tooth fragments, a large jaw (U.S.N.M. 

 No. 22458) with damaged teeth associated with some fragments of a 

 skull. These are of a form averaging larger than that represented by 

 the La Barge materials, as might be expected in single species showing 

 progressive increase in size. 



As isolated Mi in the Princeton collection from the Cathedral Bluffs 

 (P.U. No. 161 13), here figured (pi. 7, fig. 4) in comparison with La 

 Barge and Bitter Creek specimens, is scarcely larger (only 0.2 mm. 

 longer at the roots) than this tooth in the New Fork jaw. It would 

 appear to be close to typical D. altidens. 



Some fragments of teeth from the higher slopes of Fossil Butte 

 are of a moderately robust form, tentatively referred to D. altidens. 

 This is in keeping with the interpretation proposed by Simpson (1937, 

 p. 15) that Matthew's Lysite subspecies (mutant) should probably 

 be included in D. altidens. 



VIVEKRAVUS, cf. ACUTUS Matthew 

 (Plate 7, figure 9) 



A right ramus of the mandible with P4 and Mi (U.S.N.M. No. 

 22465) and a second specimen with only P4 from the Bitter Creek 

 locality are found to be of a species of Viverravus distinct from 

 V. lutosus of the later horizons of the Wasatch. The teeth are smaller, 

 particularly the premolars, than in V. lutosus, and the talonid basin 

 of the camassial appears relatively narrower. The two specimens 

 correspond more closely to Viverravus acutus, and P4, particularly 

 in the second specimen, is very little different in size. Mi in No. 22465, 

 however, appears somewhat smaller and relatively more slender than 

 this tooth, which is incomplete, in the lower Gray Bull or Sand Coulee 

 type. The teeth in all but one of the other Gray Bull jaws observed 

 are indeed larger than in the type. Nevertheless, the differences are 

 not great and the Bitter Creek materials may be tentatively referred 

 to this species, although they may possibly represent a small mutant. 



A lower carnassial in the collections of the University of California 

 (No. 43821) from the Knight about 11 miles north of Baggs, Wyo., 

 and between 100 and 150 feet below the Tipton tongue is surprisingly 

 close to Ml in the above Bitter Creek jaw. It cannot be referred to 

 V. lutosus although the horizon represented seems characterized by 

 that species. It is also tentatively allocated to V. acutus. 



