128 CHARLES S. PROSSER 



from the Upper Coal Measures to the Permian, as first defined by Murchison for 

 Russia, and belong to the division which has generally been called Permo-Carbonif- 

 erous, in this country. In accordance with the views of the majority of present 

 European geologists familiar with this problem it is probably better to include the 



Permo-Carboniferous rocks of Kansas in the Permian series The Marion 



formation belongs to the undoubted Permian and contains only fossils which are 

 characteristic of that series. 



In Russian geological literature the term Permo-Carboniferous 

 frequently occurs, the lower terrane of which is the Artinsk and the 

 upper the Kungur; but the later standard European works on 

 geology refer these terranes to the Permian.' I have followed them 

 in putting the Kansas Permo-Carboniferous in the Permian. Dr. 

 Kayser in the last edition of his Formations kunde states that the 

 Permian formation of the interior Russian-Uralian district is divided 

 in the following manner: 



Tartarian stage \ 



Russian Zechstein (limestone) f .... 



„ r , > Permian m the strict sense. 



Kupfer sandstone ( 



Lower Red Beds / 



Kungur stage ) 



Artinsk stap-p 1 Permo-Carboniferous of Russian geologists.^ 



Dr. Kayser has written me recently that: 



As far as the Artinsk formation is concerned, I still entertain the same 

 opinion as at the time of the writing of the last edition of the Formationskunde, 

 i. e., T look upon it as the base of the Permian. The Ammonite fauna of the 

 Artinsk, which varies considerably from the Carboniferous, and the flora seem to 

 me in this respect decidedly significant. 3 



The line of division between the Carboniferous and Permian 

 I always considered a debatable one. In my paper of 1902 it was 

 thought that the evidence favored drawing it at the top of the 

 Neosho member of the Garrison formation or at the base of 



I Geikie, Text-Book of Geology, 4th ed., Vol. II, 1903, p. 1077; De Lapparent 

 Traits de geologie, 4th ed., Vol. II, pp. 968, 993; Kayser, Lehrhuch der Ceologie, 3d ed.,, 

 pt. II, 1908, p. 290; Freeh, Lethaea geognostica, Theil I, "Lethaea palaeozoica," 2. Bd.) 

 2. Lief., 1899, chart opposite p. 394, and 3. Lief., 1901, pp. 493-99; Credner, Elemente 

 der Geologie, 9th ed., 1902, p. 517; Toula, Lehrhuch der Geologie, 1900, pp. 219, 238. 



2 Lehrhuch der Geologie, Pt. II, 1908, p. 290. 



3 Letter of November 11, 1909. 



