212 J. Marcou — Jura and JVeocomian of Arkansas, etc. 



Break. . 



Jura. 



Until now this upper part of the Jurassic 

 formation has been best preserved in 

 the Tucumcari region. A few remnants 

 exist near Belvidere (Kansas), at Kent 

 (Texas), and possibly in the Choctaw 

 Nation. 



Zone of the Gryphcea Tucumcarii and 

 Ostrea Marshii. 



Best developed in Pike County, Arkansas, 

 and Bosque County, Texas. 



Represented in Kansas by the Cheyenne 

 sandstone ; at Pyramid Mount, New 

 Mexico, by the yellow and white sand- 

 stone ; and at Kent, Texas, by sand- 

 stone called Paluxy. 



Resting on the New Red sandstone or 

 according to different parts of the country. 



Cambridge, Massachusetts, May, 1897. 



the Palezoic series 



