PEALE.] 



KESUME CENOZOIC EOCKS — TERTIARY. 



639 



meter in mean diameter ; they thus give the cases a granulated appearance. Nearly 

 all the cases are filled Avith calcareous material, but some are empty for a short dis- 

 tance from their mouth, and in one case the inner liniug of this part of the case has a 

 coating of minuter calcareous particles, evidently deposited therein after the case was 

 vacated. As the present thickness of the walls indicates (as also the size of the at- 

 tached pebbles), the silken interior lining of the case must have been very stout. This 

 follows also from the appearance of one or two which have been crushed ; for they 

 have yielded along longitudinal lines, indicating a parchment-like rigidity in the entire 

 shell. In one of the specimens the outer coating of heavier pebbles has in some way 

 been removed by weathering, and has left a scabrous surface, apparently produced by 

 minute, hard grains entangled in the fibrous meshes of the web ; it still, however, re- 

 tains its cylindrical form. 



The size of the case, its form, and the material from which it is constructed, seem to 

 indicate that it belonged to some genus of Limnophilidce near Anabolia. 



The following is the list of shells and fish and plants collected during 

 the season : 



List of fossils from the Green River Group. 



MOLLUSCA. 



Goniobasis tenera. 



TJnio Haydeni. 



Cypris. 



Big Sandy, near mouth of Little Sandy, 

 Green Biver Basin, Wyoming Territory. 



Ham's Fork above Granger. 



FISHES. 



Mioplosus labracoides. 

 Mioplosus abbreviatus. 

 Mioplosus sp. H 

 Dapedoglossus testis. 

 D ip lomystus humilis. 

 Diplomystus analis. 

 "Priscacara serrata. 

 Priscacara serrata (young). 

 Priscacara pealei. 

 Clastes ferox. 



On Twin Creek, near southern edge of 

 Ham's Fork Plateau, about latitude 41° 

 55', longitude 110° 48', Wyoming Ter- 

 ritory. 



FLORA 



Myrica n. sp. 

 Ostrya n. sp. 



Branch of Twin Creek, near Sublette's 

 Boad, Ham's Fork Plateau, Wyoming 

 Territory. 



. BRIDGER GROUP. 



The areas of the Bridger Group are few, and are all limited to the south- 

 eastern portion of the district. The largest area extends northward from 

 Ham's Fork toward Slate Creek, breaking off in low bluffs in which the 

 sombre clays and sands of the group are exposed. Between the mouth 

 of the Big Sandy and the Green, on the east side of the former, there 

 are variegated sands and marls much like those of the Wahsatch Group. 

 They are, however, above the Green River shales, and have therefore been 

 referred to the Bridger Group. They weather into Bad Lands. The beds 

 of this group were not observed north of Slate Creek. On the east side 

 of the Big Sandy north of the Green there appeared to be isolated 

 patches of the beds, but they do not extend far to the northward. 



