128 GEORGE H. GIRTY 



In connection with the correlation of the Wichita formation 

 with the Permian of Europe, it may be well once again to consider 

 the use and definition of the term Permian. 



As is well known, Murchison correlated with the English " Mill- 

 stone grit" a series of sandy beds which underlies the typical 

 Russian Permian, and therefore this series, to which the name 

 Arta beds or Artinskian was subsequently given, was distinctly 

 excluded from the original or typical Permian. It has since been 

 recognized that the Arta beds are not the equivalent of the "Mill- 

 stone grit," and that the fossils which they contain show affinities 

 with both the "Upper Carboniferous" below and the Permian 

 above. The Artinskian therefore came to be called also "Permo- 

 Carboniferous," and by many writers it is included with the other 

 under the name Permian. 



While the typical Permian is usually underlain by the sandstones 

 of the Artinskian, over a considerable and well-defined area a heavy 

 series of limestones and dolomites has been found to intervene. 

 This apparently lenticular mass has been called the Kungur-stufe, 

 and on paleontologic evidence has been by Tschernyschew united 

 with the Artinsk and included under the term " Permo-Carbonif - 

 erous," which, therefore, comprises two divisions, the Arta beds 

 below and the Kungur beds above. 



Now, the propriety of including the original Permian and 

 " Permo-Carbonif erous " in a single group is, of course, a question 

 quite apart from the nomenclature which should be used, and it is 

 a question with regard to which one who has not studied the rocks 

 and fossils in the typical region can hardly render an authoritative 

 opinion. There seems to be European authority both for exclud- 

 ing the "Permo-Carbonif erous" from the Permian and for includ- 

 ing it with it, the greater number of writers, it may be, adopting the 

 latter course. 



As for the plants, Mr. White states that "from the paleobotanical 

 standpoint the Artinsk stage of Russia is clearly Permian." 



My own knowledge of the facts is only that of the library, but 

 I should judge that the faunal break was greater between the 

 Gschelian and the " Permo-Carbonif erous " than between the 

 " Permo-Carboniferous " and the original Permian. That is, of the 



