14 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [bull. 106. 

 General section of the Cretaceous rocks of Nebraska. 



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Divisions and subdivisions. 



Gray, ferruginous, and yellowish sand- 

 stone and arenaceous clays, contain- 

 ing Belemnitella bulbosa, Nautilus 

 Dekayi, Placenticeras placenta, P. 

 lenticnlaris, Scaphites Conradi, S. 

 Nicolleti, Baculites grandis, Pyropsis 

 Bairdi, Piestochilus Culbertsoni, Py- 

 rifusus Newberryi, Ancbura Ameri- 

 cana, Pseudobuccinum Nebrascensis, 

 Mactra Warrenana, Cardium sub- 

 qnadratum, and a great number of 

 other moll uscanfossils, together with 

 bonca of Mosasaurus missouriensis, 

 etc. 



Dark-gray and bluish plastic clays, 

 containing, near the upper part, 

 Nautilus Dekayi, Placenticeras pla- 

 centa, Baculites ovatus, B. compres- 

 sus, Scaphites nodosus, Dentalium 

 gracile, Crassatella Evansi, Cucul- 

 l;ca Nebrascensis, Inoceramus Sagen- 

 sis, I. Nebrascensis, I. Vanuxemi, 

 bones of Mosasaurus missouriensis, 

 etc. 



Middle zone nearly barren of fossils. 



Lower fossiliferous zone, containing 

 Ammonites complexus, Baculites 

 ovatus, IS. eompressus, Heteroceras 

 Mortoni, Il.tortum, H. umbilicatum, 

 II. cocblcatum, Ptychoceras Mortoni. 

 Odontobasis vinculum, Anisomyon 

 borealis, Amauropsispaludiniformis, 

 Inoceramus subladvis, I. tennilinea- 

 tus. bones of Mosasaurus missou- 

 riensis, etc. 



Dark bed of very tine unctuous clay, 

 containing much carbonaceous mat- 

 ter, with veins and seams of gypsum, 

 masses of sulphuret of iron, and 

 numerous small scales of lishes. 

 Local; filling depressions in the bed 

 below. 



Localities. 



Fox Hills, near 

 Moreau river; 

 near Long lake, 

 above Fort 

 Pierre; along 

 the base of the 

 Big Horn moun- 

 tains, and on 

 North and South 

 Platte rivers. 



Sage creek, Chey- 

 enne river, and 

 on White river 

 above the Mau- 



vaises Terrcs. 



Fort Pierre and 

 out to Bad 

 Lands; also 

 down the Mis- 

 souri on the high 

 country to Great 

 Bend. 



Great Bend of the 

 Missouri below 

 Fore Pierre. 



Near Bijou Hill, on 

 the Missouri. 



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