PENNSYLVANIC-PERMIC PERIOD 569 



In the Kansas section, near the top of the Sumner, occurs a flora that 

 Sellards regards as of Lower Permic age. This conclusion is borne out by 

 White's 199 statement that 



"if the composition of the entire flora proves to be of so young a character as 

 the material described or placed in my hands by Mr Sellards, his conclusion 

 that the beds are of so late date as the Lower Permian will appear to be fully 

 justified. . . . Probably of a date fully as late as the earlier of the floras 

 generally referred to the Permian in western Europe." 



The Sumner formation also yields an abundant insect fauna very dif- 

 ferent from that of the Pennsylvanic. But few of these are as yet de- 

 scribed by Sellards. 200 "Over two thousand specimens are now at hand 

 [and give] the most complete record of Permian insect life thus far ob- 

 tained." Ephemerids are unknown beneath the Permic, and Sellards 

 here described 12 new species. 



In Texas occur far more characteristic Oklahomian fossils associated 

 with many Pennsylvanic survivors. In the Albany series are the ammo- 

 nites Phacoceras dumbhi (also in the Fort Eiley limestone of Kansas), 

 Medlicottia copei, Popanoceras wdlcoUi, Paralegoceras taylorense,Waagen- 

 oceras cumminsi, and Coloceras globulare. Of nautiloids occur Domato- 

 ceras simplex, D. militarium, Tainoceras occidentalis (also below j, Tem- 

 nocheilus winslowi (below), and T. conchiferus. In the Double Moun- 

 tain series (which may be but another petrologic phase of the Albany and 

 Wichita), Waagenoceras hilli is found. These forms are thought to hold 

 the time of the European Artinsk, referred by stratigraphers to the Permo- 

 Carboniferous or the Lower Permic. 



Concerning the divisions of the Wichita, Clear Fork, and Double Moun- 

 tain, Adams 201 states : 



"It may be said that there is little reason to believe that they should be any 

 longer retained, since they have no stratigraphic significance. It appears that 

 what have been called the Clear fork and Wichita divisions by Mr Cummins are 

 the equivalents, in part at least, of the Albany." 



The Wichita-Brazos region has been restudied by Gordon, 202 and his con- 

 clusions are as follows : The Wichita and Clear Fork, usually regarded as 

 of Permic age, 



"when traced along their strike toward the southwest, are found to grade into 

 those included under the terms Cisco and Albany. ... An abundant marine 

 fauna characterizes the beds toward the south. In the Red Bed region marine 



199 White: Bull. no. 211, U. S. Geological Survey, 1903, p. 117. 



200 Sellards : American Journal of Science, September, 1906, and May, 1907. 



201 Adams : Bull, of the Geological Society of America, vol. 14, 1903. 



202 Gordon : Science, May 7, 1909, p. 752. 



XLIX — Bull. Geol. Soc. Am., Vol. 20, 1908 



