136 Cretaceous. 



Prof. E. D. Cope* called the Judith River Group No. 6 Cretaceous. 

 He shoAved its con form ability with the underlying marine Cretaceous, 

 and gave a section 332 feet in thickness, though its maximum is not 

 less than 500 feet. His section in ascending order is as follows: 



Arenaceous marl (with Dinosauriau bones near the top) .... 125 feet. 



f Sandstone, 1st 5 



Sandstone 6 



Impure lignite 2 



Sandstone, 2d 10 '^ 



Impure lignite 4 



Unio bed 30 " 



Eusty sandstone (with fresh water shells) 25 " 



Arenaceous marl (with petrified wood) 50 " 



Sandstone, 3d 15 



Marl 20 " 



Reddish shale 10 " 



Lignite 5 



Shale 7 



Black shale and lignite 34^ " 



Bed of Ostrea sub trigonal is 15 " 



Total. 3321 feet. 



The presence of Dinosaurians, gar fishes, turtles, Physa, Viviparus 

 and Unio prove the fresh water character of the strata, while the 

 Ostrea indicates a return to brackish water. 



Dr. C. A. Whitef described, from the Jucjith River Group at Cow 

 Island and Dog creek, a tributary of the Upper Missouri river, in 

 Montana Territory, Unio ctyptorhynchus, U. senectus, U. primaevus, 

 Anodonta propatoris, Bulinus atavus, and Physa copei. 



Prof. F. B. Meek+ described, from near Laporte, Colorado, Anomia 

 rcctiformis; from East Canon creek, Wasatch Range, Utah, Cac^dlma 

 obliqua, Mactra emmonsi; from Cooper creek, Laramie Plains, 

 Wyoming, Axinoia wyomingensis; from Red creek, Uinta Mountains, 

 Utah, Mactra arenaria; from East Canon creek, Utah, Ilactra utah- 

 ensis^ ■Tellina isonema, T. modesta, Gyrodes dejjressa, and Anchura 

 fusiformis. 



Prof. C. A. White§ described, from east of Impracticable Ridge, 

 Utah, Ostrea prudentia; from near Pueblo, Colorado, Inoceramus 



- Bull U. S. Geo. Sur., Vol. 3., No. 3. 

 + Bull U. S. Geo. Sur., Vol. 3., No. 3. 

 X IT. S. Geo. Expl., lOth parallel. 

 g Wheeler's Sur. W. 100th Mer., Vol. 4. 



