276 STANTON 



Corbicula cytheriformis M. & H. 

 Corbicula fracta Meek 

 PanopcBa simulatrix Whiteaves? 

 Neritina volvilineata White 



This is evidently a recurrence with sHght modifications, of the 

 brackish- water fauna found at the top of the Mesaverde and it is prac- 

 tically identical with the brackish- water element of the fauna at Black 

 Buttes. 



Considerably higher in the section near the middle of the ' 'Lara- 

 mie" the following fresh-water shells were obtained: 



Unio goniamhonatus White 

 Unio stantoni White 

 Unio verriicosiformis Whitfield 

 Unio hrachyopisthus White? 

 Tulotoma thorn psoni White 

 Goniohasis sp. 



All of these species except one are found at Black Buttes and that 

 one occurs at Hell Creek and Converse County. 



The stratigraphic, areal, and structural relations and the faunal 

 evidence all seem to justify the correlation of the "Laramie" of this 

 area with the Black Buttes coal group. 



Above his Laramie Smith recognizes two unconformities between 

 which there are coal-bearing strata with a total thickness estimated 

 at 8780 feet which he treats as ** undififerentiated Tertiary." The 

 lower part is conglomeratic, especially about 1000 feet above the base, 

 where the conglomerate contains pebbles of both Paleozoic and Cre- 

 taceous rocks. Fossil plants recognized as Fort Union by Knowlton 

 have been obtained from several horizons in this thick series. 



Above the upper unconformity there are 900 to 1800 feet of coal- 

 bearing beds referred by Smith to the Wasatch. The basal con- 

 glomerate is in large part derived from granite with some sedimentary 

 pebbles. The most important paleontologic evidence as to the age of 

 this formation consists of some teeth of Coryphodon, a mammalian 

 genus characteristic of the Wasatch, and an unstudied flora which is 

 said to be different from the Fort Union. The fresh-water shells 

 obtained also indicate Eocene later than Fort Union. 



Carbon County, Wyoming. — The area adjoining that mapped by 

 E. E. Smith on the east and extending from Rawlins about 50 miles 



