ITS T. W.Stanton — Fox Hills Sandstone. 



Lucina occidentals (Morton) 



Tancredi americaiia M. & 11. 



Pi'otocardia suJxpiadnda E. & S. 



Cidlista dewcyi ]\I. «fc II. 



Tdl'ma scitula M. & II. 



Jlactra wnrremina M. & II. 



Ctfspidarki ventricosa, (M. & II.) 



LuiuUia occldentaUs M. & II. 



Jjunatia concinna H. & M. 



Lunatia snhcrassa M. & II. 



Anchura{Drepai»och'dufi) americana (E. & S.) 



Pyropsis bairdi M. & H. 



Fasciolaria {Piestochilas) culbertsoni M. & H. 



Fasciolaria buccinoides M. & H. 



Pyrifusus newberryi M. & H. 



Fiisus (Scrrifusus) dakotensis M. & H. ' 



Ci/Uchna volvarla M. & H. 



Ilaminea minor M. & H. 



Cinulia concinna M. & H. 



Sphenodixcus lenticulnris (Owen) 



iScaphites conradi (Morton) 



Scaphites conradi var. intermedins Meek 



iScaphites abyssinus (Morton) 



Scaphites nicoUeti (Morton) 



Scaphites cheyennensis (Owen) 



At some localities as on Grrand liiver near Dirt Lodge Creek 

 the sandstones are filled with Tancredia americana M. & H,, 

 witli very few other species. 



At the top of the Fox Hills sandstone with its purely marine 

 fauna there is a rather thin but widely distrib^^ted brackish- 

 water bed, already several times referred to, which contains 

 Ostrea, Anomia, Corbicula, Melania, etc., in great abundance. 

 The zone in which this fauna occurs varies in thickness from 3 or 

 4 feet up to 40 feet and is lithologically very similar to the 

 underlying marine beds, but its base is irregular at many places 

 and shows channeling and other evidence of erosion. It was 

 therefore regarded by the field geologists as the basal member of 

 the overlying Lance formation resting unconformably on the 

 Fox Hills. In the study of this brackish-water bed evidence was 

 found at several localities, distributed over a considerable area, 

 that there is a distinct transition without a break of any impor- 

 tance between the marine Fox Hills sandstone and the brackish- 

 water deposit. The paleontologic evidence consists of distinc- 

 tive Fox Hills species belonging to such marine genera as 

 Scaphites, Lunatia, and Tancredia, found directly associated in 

 the same bed with the brackish- water forms and occurring with 

 them in such a way that they must have lived together or near 



