244 STANTON 



*Unio biesopoides Whitfield 

 *Unio browni Whitfield 

 *Unio letsoni Whitfield 

 *Unio pyramidntoides Whitfield 

 *Unio verrucosijormis Whitfield 



Unio (several undescribed species) 



Anodonla parallela White 



Anodonta? sp. 

 '\Sph(Erinm planum M. & H. 



Sphccrmm sp. 



Viviparus sp. 

 '\Tuloloma thompsoni White 



Canipeloma? sp. 

 X^^Campeloma multilineata M. & H. 

 XGoniobasis teniiicarinata M. & H. 

 X^Thaumastus limnccijormis M. & H. ? 



Physa copei var. canadensis Whiteaves? 



Helix vetusta M. & H ? 



Limnoda sp. 



* Species so marked occur in the "Hell Creek beds." 

 t Species so marked occur at Black Buttes. 



X Species so marked and possibly the two species of Sphagrium, theCampe- 

 loma (?) and the Viviparus occur in the overlying Fort Union strata. 



The invertebrate fauna as a whole is remarkably distinct from all 

 those that succeed it in the American Eocene, although there are a 

 few species that seem to survive in the typical Fort Union without 

 change. If the resemblances seen in some of the species of Unio now 

 living in the Mississippi Valley really mean direct descent from these 

 species in the "Ceratops beds" (which may well be doubted) the con- 

 necting forms have not been preserved in the rocks of the region, 

 although fresh-water shells are abundant in the Fort Union, Wasatch, 

 and later Eocene formations. The various links that connect the 

 fauna and the strata containing it with the Cretaceous will appear 

 in the descriptions of other areas and in the general discussion, 



Weston County, Wyoming. — Directly north of the Converse County 

 exposures and forming part of the same continuous area Barnum 

 Brown collected dinosaurs and fossil plants from outcrops on Seven 

 Mile Creek and Alkali Creek, north of Cheyenne River, and has pub- 

 lished short lists of plants (repeated in Knowlton's paper) from two 

 horizons on Seven Mile Creek. Those from the lower bed associated 

 with Claosaurits {^TracJiodoi) include a fig and three species of 



