194 THE JOURNAL OF GEOLOGY. 



But their known fauna and flora have been too limited and 

 too indecisive to enable us to correlate subdivisions with those 

 of other Carboniferous areas, since collections have been made 

 in but few places, and these chiefly in sandstones, where the 

 preservation of fossils is usually unsatisfactory, and their deter- 

 mination uncertain. 



But the Lower Coal Measures correspond in a general way 

 to the Strawn and the Canyon divisions of Texas, the Pottsville 

 conglomerate series, the Lower Productive Coal Measures, and 

 part of the Lower Barren Coal Measures of Pennsylvania. 



The Upper Coal Measures. — The Arkansas Upper Coal Meas- 

 ures correspond to the lower part of the Cisco of Texas, and 

 belong just at the top of the true Carboniferous, and below the 

 transitional Permo-Carboniferous or Artinsk stage, to which latter 

 age the uppermost Cisco beds of Texas, with Ammonites {^Popan- 

 oceras) parkeri^ Heilprin belong. These may be the equivalents 

 of the Poteau mountain marine beds. 



The lower Permo-Carboniferous strata of Kansas and Nebraska 

 are probably also to be correlated with the Artinsk^ stage, although 

 Waagens classes the entire series with the ammonite-bearing 

 beds of northern Texas, described by Dr. C. A. White in Bulle- 

 tin 'J'] of the U. S. Geological Survey. The latter Texas beds, 

 however, belong above the Artinsk stage, and in the true Per- 

 mian, and are probably of the same age as the middle division 

 of the Middle Productiis limestone of the Salt Range. 



Waagen, in "Salt Range Fossils, Geological Results," p. 

 238, gives a comparative table, showing the relationship of the 

 upper Paleozoic strata all over the world. While the position 

 . assigned some of the American deposits does not agree with 

 that accepted by most American geologists, still the table is use- 

 ful for comparison, and it has been freely used in compiling the 

 comparative table at the end of this paper. 



^ This horizon is at the top of the Cisco, and above the horizon of Goniatites 

 marianus. 



^Karpinsky : " Ammoneen der Artinsk-Stiife," p. 92. 



3 Salt Range Fossils, Geological Results, p. 204. 



