NO. I LOWER EOCENE MAMMALIAN FAUNAS — GAZIN 43 



Additional esthonychid materials from the New Fork member, in- 

 cluding a lower jaw (U.S.N.M. No. 22124; pi. i, fig, 3) with Dp4 

 and the first two molars, shows that a somewhat larger variant of 

 Esthonyx acutidens than that in the La Barge fauna is represented 

 in the New Fork fauna. The lower molars are noticeably high crowned 

 and the talonid portions are large, as characteristic of the Lost Cabin 

 species. The teeth in No. 22124 are of a size that permits good occlu- 

 sion with upper teeth in the rostral portion of a skull from the Lost 

 Cabin figured in 1953 (Gazin, p. 26, fig. 8). 



ESTHONYX, sp. 



An upper fourth premolar in the Princeton collection, No. 161 29, is 

 reported to be from the "Hiawatha" member exposed north of Baggs, 

 Wyo., on the east side of the Washakie Basin. It is comparatively 

 small for Esthonyx acutidens, smaller than would be expected in the 

 Dad local faunule, and the tritocone is rather weakly defined for 

 either E. acutidens or E. bisulcatus. The horizon in the "Hiawatha" 

 member is not given. Possibly the specimen came from beds as low 

 as those worked by McKenna to the south of Baggs. 



No further material of Esthonyx than that mentioned in 1952 was 

 found in the type section for the Knight near Knight station. 



TROGOSUS?, cf. LATIDENS (Marsh) 



The last upper molar of the large tillodont Trogosus was recorded 

 by Morris (1954, pi. 21, fig. i) as coming from the Cathedral Bluffs 

 member of the Wasatch on the east side of the Washakie Basin, sec. 4, 

 T. 15 N., R. 93 W. The tooth was originally identified by me and 

 thought to be strong evidence of a Bridgerian age for the Cathedral 

 Bluffs beds. An earlier record in which a similar isolated tooth of an 

 advanced tillodont, possibly of the same form, collected by Nace 

 (1939) in beds regarded as Cathedral Bluffs in the Red Desert region 

 to the north, was identified by Simpson as "Tillotherium" and like- 

 wise believed to be Bridgerian. I am now convinced, from the evi- 

 dence presented by the associated fauna, that the Cathedral Bluffs 

 beds are of Lostcabinian or late Wasatchian age and that Trogosus 

 was not restricted to Bridgerian time but evidently appeared earlier, 

 although there is no evidence to show that it was actually associated 

 in the same horizon with Esthonyx. There would seem to be, how- 

 ever, too much difference between these forms in the Cathedral Bluffs 

 to postulate evolution in situ. 



