PALEOZOIC AND MESOZOIC BORDER-LINE 5 I 5 



classing it in the Mesozoic. There can be no controversy as to 

 its age, which is approximately equivalent to that of the lower 

 Productus limestone of India. It lies conformably on the Coal- 

 measures, and contains many species that have ranged up from 

 the latter. 



But above the Wichita Permian lies the great series of the 

 Red Beds. These have been assigned sometimes to the Permian 

 and sometimes to the Trias, and they, doubtless, belong to both. 

 Marine fossils have been found in these Red Beds only in three 

 places. The Geological Survey of Texas ' found in the Double 

 Mountain formation at the falls of Salt Croton Creek, Kent 

 county, Texas, Medlicottia, Waagefioceras, and Pleiirophorus, all 

 akin to forms from the Wichita beds. The writer has examined 

 these forms and recognizes them to be still typically Permian 

 in character, although they are very near the top of the forma- 

 tion. Above these beds lies the freshwater " Dockum " series 

 referred by Cope to the Trias. 



C. N. Gould ^ has recently found marine and brackish-water 

 Permian fossils in the Red Beds of Oklahoma, in the Cimmaron 

 series; the forms still being of Paleozoic type, such as Conocar- 

 dimn, Aviculopecten, Schizodus, Pleurophorus, and Bakevellia. The 

 stratigraphic position of these is equivalent to the Double 

 Mountain beds of Texas, and they belong unequivocally to the 

 Paleozoic. 



In the Red Beds of Utah, at Ft. Douglas near Salt Lake City, 

 F. Freeh 3 has found Pleurophorus imbricatus Waagen, Allorisma 

 conf. elegans King, Emotidia aspinzvallensis Meek, Schizodus 

 schlothehni King, and Dalmanella sp. indet., a fauna that would 

 pass for Paleozoic anywhere, and belongs in the same horizon as 

 the Double Mountain beds of Texas and the Cimmaron series of 

 Oklahoma and Kansas. They are the homotaxial equivalents 

 of the Upper Permian. 



'Geological Survey of Texas, Second Annual Report, 1890. Report on the Geol- 

 ogy of Northwestern Texas, by W. F. Cummins, p. 408. 



'Jour. Geol., Vol. IX, 1901. No. 4, p. 337. 



3Lethaea Geognostica, Vol. II, Lieferung 3. 1900, p. 515. 



