﻿202 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



MEASUREMENTS OF MANDIBULAR FRAGMENT OF BUNOPHORUS ETSAGICUS (IN 



MILLIMETERS) 



Lengtli Width 



Pr-Ma 31.5 



Mi-s 23.3 



P4 7.5 4.4 



Ml 7.0 6.0 



M2 Y.4 6.5 



Ms 9.0 7.0 



CDOO 



USNM 

 /6370 



Figure 79. 



-BunophoTus etsagicus (Cope), U.S.N.M. No. 18370; occlusal view of teeth and 

 lateral view of left mandible, X Wi. 



Genus DIACODEXIS Cope 



DIACODEXIS OLSENI Sinclair 



(loc. 



U.S.N.M. No. 18472, left mandibular fragment with P4-M2 



No. 48FE78). 



This material does not permit anything to be added to Sinclair's 

 p. 292) discussion of the species. 



(1914 



SUMMARY 



Since Tertiary reptiles are yet too poorly known to be useful as 

 horizon markers, they will be omitted from the summary. From the 

 Boysen Reservoir area 23 species of fossil mammals have been identi- 

 fied; 14 of them (see Table 2) are common to the Lost Cabin faunal 

 zone of the Lower Eocene, 2 of them to the Gray Bull, and 2 others 

 are common to both the Gray Bull and the Lysite. Consequently, 

 there can be little doubt that these deposits must be referred to the 

 Lost Cabin faunal zone. However, on structural grounds these beds 

 may be somewhat younger than the type section on Alkalai Creek. 



There are about 250 feet of the Wind River formation exposed in 

 the Boysen Reservoir area. For the most part the formation consists 

 of drab greenish-gray gj^psiferous clays with yellowish, usually fine- 

 grained, channel sandstones forming nearly vertical cliffs. While 

 most of the gypsum is probably secondary there are numerous areas of 

 local concentration caused by seepage of ground water or by capillary 



