329 



referred to Trogosus casloridens, on page 71 of the present work, and 

 represented under the same name in Figs. 1 to 3, Plate V, that I noticed 

 the identity in character of the corresponding tooth. Previous to the 

 description of the jaw referred to Trogosus, Professor Marsh had pub- 

 lished a notice of a similar tooth under the name of PalcBosyops minor. 



It is not improbable, after all, that Trogosus may be distinct from Anchip- 

 podus, for there are several genera which, while they have the inferior 

 true molars alike, have the premolars and upper true molars quite differ- 

 ent. While regarding Trogosus the same as Anchippodus, for the same 

 reason I have considered Trogosus castoridens the same as Anchippodus 

 riparius, for the specimen upon which the latter was originally made known 

 is identical in form and size with the corresponding tooth in the jaw of 

 the former. Nor is it improbable that they are the same, for they were 

 probably of contemporaneous age, and perhaps extended throughout the 

 continent, as the American mastodon did at a later period. Specimen 

 from the Bridger Eocene of Wyoming 



Anchippodus vetulus. 



Trogosus vetulus. Leidy : Pr. Ac. Nat. Sc. 1871, 229 ; Haydeu's Rep. Geol. Sur. 

 Montana 1872, 3G0. 



Noticed on page 75, under the name of Trogosus vetulus, and represented, 

 with the name of Anchippodus vetulus, in Fig. 43, Plate VI. From the 

 Bridger Eocene of Wyoming. 



NOTHARCTUS. 



NOTHARCTUS TENEBROSUS. 



Leidy: Pr. Ac. Nat. Sc. 1870, 114. 



Described page 86, and represented by Figs. 3b', 37, Plate VI. From the 

 Bridger Eocene of Wyoming. 



Proboscidea. 



ELEPHAS. 



Elephas americanus. 



Delcay : Nat. Hist. Now Fork, ZooL, 1842, 1, 101. Leidy : Ext. Mam. N. America 



1869, 398. 

 Elephas Columbi. Falconer: Quart. Jour. Geol. Soc. 1S57, 319, &c- 

 Elephas Texianus. Owen : Eep. Brit. Asso. 1858, SI, &c. 

 Elephas imperator. Leidy: Pr. Ac. Nat. Sc. 185S, 10. 



42 a 



