329 



referred to Trogosus caslorldens, ov, page 71 oi' Uie 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 (o the 

 descrijition of the jaw referred to Trogosus, Professor Marsh had puh- 

 Hshed a notice of a simiUir tooth under tlie name of Falcnosyops 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 castoriclens the same' as Anch'qjpoclus 

 riparlus, for the specimen upon which the latter was originally made known 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; Ilaydeii's Kep. Gcol. Snr. 

 Moutaua 1872, 3G0. 



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

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

 Bridger Eocene af Wyoming. 



NGTHARCTUS. 



NoTHARCTUS TENEBROSUS. 



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



Described page 86, and represented by Figs. 3(i, 37, Plate VI. From tlie 

 Bridger Eocene of Wyoming. 



Proboscidea. 



ELEPHAS. 



Elepiias americanus. 



Dekay : Nat. Hist. New Tork, Zoo]., 1842, 1, 101, Leidy : Ext. Jlaiii. N. America 



1869, 398. 

 Elvphas Golumbi. Falconer: Quart. Jour. Geol. Soc. 1857, .'!19, &{•,. 

 Elcphas Texiauus. Owen : liep. Brit. Asso. 1858, 84, &c. 

 Elcphas imperator. Leidy : Pr. Ac. Nat. Sc. 1858, 10. 



42 G ' 



