NO. I LOWER EOCENE MAMMALIAN FAUNAS GAZIN 39 



Also, as Morris has pointed out, the molar talonid basins are more 

 strongly crenulated. Only the type specimen, a lower jaw (P.U. 

 No. 14972), has been discovered. The three species A. abbotti, A. noc- 

 tivagus, and A. zvitteri would seem to present a gradational sequence 

 characterized principally by the development of P4, except for the 

 rather unusual specimen from the early Wasatchian of the Red Desert. 



UINTASOREX, cf. PARVULUS Matthew 

 (Plate 5, figure 4) 



A minute jaw fragment with M2 and M3 (U. of Wyo. No. 1646), 

 lent to me by Paul McGrew, is described as coming from a locality 

 of Lost Cabin age in the Red Desert region. The specimen cor- 

 responds well in size with the type of Uintasorex parvuhis (A.M. 

 No. 12052) although the same teeth are not included. It is about in- 

 termediate in size of the posterior molars between the Yale specimen 

 (No. 13519) and jaw portions from the "Upper Fossiliferous Hori- 

 zon" of the Green River at the Powder Springs locality in the Uinta 

 Basin. Correspondence to Uintasorex is seen in the anteroposteriorly 

 abbreviated trigonid, the large Otiiomys-Wke talonid and the distinc- 

 tive Cynodontomys-Vikt notch between the entoconid and closely ad- 

 jacent hypoconulid of Mg. It resembles the Green River material 

 somewhat more than the Yale Bridger specimen in the less constricted 

 and less projecting hypoconulid of M3, but perhaps differs from both 

 in less evidence of an external cingulum on the two molars. 



This form is clearly related to, but much smaller than, McKenna's 

 ( i960) Niptomomys doreenae from the Four Mile fauna, although the 

 latter has relatively wider talonid basins. A somewhat closer cor- 

 respondence is seen to the specimen described as Cf. Niptomomys 

 doreenae in the less widely expanded talonid basins and in the ap- 

 pearance of the cingulum, but differs from it in that Cf . Niptomomys 

 doreenae, though smaller than the Four Mile type, is somewhat larger 

 than the Red Desert specimen and shows a more discernable, lingually 

 placed paraconid on both of the molars, which, incidentally, look very 

 much alike. 



PHENACOLEMURIDAE 



PHENACOLEMUR, cf. PRAECOX Matthew 



(Plate 2, figure 6) 



Phenacolemur is so far represented in the Knight only in the Bitter 



Creek fauna. A single specimen (Y.P.M. No. 14062), a lower jaw 



portion with M2 and the posterior crest of the talonid of Mj, is pre- 



