PERMIAN. 421 



ers and somewhat greater prevalence of clayey material, these overlying beds 

 resemble the Permian strata upon which they rest. With only one known 

 exception, these gypsum bearing beds have furnished no fossils. The excep- 

 tion referred to is the discovery by Mr. Cummins, in Hardeman County, in 

 an upper stratum of these beds, of a thin magnesian layer containing numer- 

 ous casts of a species of Pleurophorus. This being a characteristic genus 

 among Permian molluscan faunas, and a prevailing form in the Permian 

 strata beneath the gypsum bearing beds, the question is suggested whether 

 the latter ought not to be regarded as constituting an upper portion of the 

 Permian. If these beds are not separable from the Permian, it seems to be 

 doubtful whether the Trias has any representation in Texas." 



Since that article by Dr. White was written, I have collected from numer- 

 ous places in the beds referred to a great many characteristic fossils of the 

 Permian, and am therefore confident Dr. White would give up his reference 

 of the upper part of the strata to the Triassic. 



Prof. Jules Marcou passed north of the Wichita Mountains on his trip 

 across the continent in 1853, and probably saw only the Double Mountain 

 Beds of the Permian; and while he did not find any fossils, he gave it as his 

 opinion that that part of the strata was Permian. Where he refers to strata 

 as Trias, in contradistinction to Permian, I have no doubt that it was the 

 same as that to which I have given the provisional name of Dockum Beds, 

 which are Triassic. I doubt if the Wichita Division occurs north of the 

 Wichita Mountains. I am also of the opinion that only a part of the Clear 

 Fork Division occurs west and north of the mountains, leaving only the 

 Double Mountains Division exposed. I have gone as far north with my ex- 

 aminations of the strata as the Canadian River north of Mobeetie, and thence 

 down that river to a point opposite the lower end of the Wichita Range, and 

 have seen only the Double Mountain Beds. The older beds of the Permian 

 may have been exposed farther northward in Kansas, but I am of the opinion 

 that southwestern Kansas has only the uppermost beds, which Mr. Hay has 

 synchronized with the strata near the mouth of the North Fork of Red River. 

 This I judge from Mr. Hay's description of the strata. He gives it the pro- 

 visional name of Jura-Trias " until paleontological evidence shall set it aside." 

 The following summary is given by Mr. Hay as his reasons for so naming the 

 strata, and which I quote here for the purpose of showing that the reasons 

 given must give place to the paleontological evidences found in the Texan 

 strata, and not for the purpose of controverting its application to the Kansas 

 strata. He says: 



"Several of the features described above suggest that the formation repre- 

 sents the Jura-Trias. These may be summarized as follows: 

 35— preoi. 



