PLA.TYCH(EEOPID^. 3 



by Leidy in the Journ. Ac. Nat. Sci. Philad. ser. 2, vol. vii. 

 p. 403, pi. XXX. figs. 45, 46. 



Presented hy Professor J. Leidy, 1876. 



47501. Cast of the greater portion of the mandible. The original 

 was obtained from the Bridger (Lower) Eocene of 

 Wyoming, U.S.A., and is described and figured by Leidy 

 in the " Extinct Vertebrate Eauna of the Western Terri- 

 tories" (Eep. U.S. Geol. Surv. Terr.), p. 71, pi. v. figs. 1-3 

 (1.S73), under the name of Trocjosus castoridens^ of which 

 ifc is the type. Presented by Professor J. Leidy, 1876. 



Eamily PLATYCHGEROPID^. 



The type genus appears to the writer ^ to be closely allied to, if 

 not identical with, the North- American Esthonyx. The position of 

 the latter has been much discussed. It was at one time placed by 



Fig. 2. 



Esthonyx hurmeisteri, Cope. -The palate and inandible; from the Wasatch 

 Eocene of Wyoming, U.S.A. |. a, lateral view of part of cranium and 

 mandible; 6, oral view of right half of palate; c, oral view of mandible. 

 (From the ' Amer. Nat.') 



^ Geol. Mag. dec. 3, vol. ii. p. 360 ; see also p. 520 of the same. 



b2 



