C. Schuchert — Russian Carboniferous and Permian. 147 



skian stage) in Russia, but the description of the Brachiopoda 

 from the Fusulina limestone of Sicily must be awaited before 

 it is possible to decide whether it does not hold a slightly 

 higher position in the stratigraphical sequence than the Artin- 

 skian deposits.' " 



" This mistake of correlation is the legitimate outcome of an 

 erroneous interpretation of the stratigraphical position of the 

 Salt Range Productus limestone. The supposition ' that the 

 entire Productus limestone forms a series, which cannot be 

 separated from the carboniferous system and that the Fusulina- 

 bearing Amb beds certainly belong to the latter,' was not my 

 fault. I followed the majority of European palaeontologists 

 in this, and my error was due to the ignorance of the leading 

 palaeontologists as to the right means of correlating rock-equi- 

 valents of anthracolithic age in Europe and in India. 



" Waagen believed the Productus limestone to be permian, 

 but to represent the entire permian system. He consequently 

 correlated the lower Productus limestone and the Katta beds 

 of the middle Productus limestone with the Artinskian stage 

 of .Russia, considering them as permo-carboniferous. The 

 palaeontological investigations of Mkitin, Freeh and Tscherny- 

 schew raised doubt as to the validity of this correlation. The 

 affinity of the fauna of the lower Productus limestone to those 

 of the upper carboniferous rocks of Russia and the Ural Moun- 

 tains and of the Carman Fusulina limestone of the Eastern Alps 

 induced Rothpletz (Palaeontographica, vol. xxxix, p. 63), 

 Freeh (Die Karnischen Alpen, p. 372), Oldham (Manual of 

 the Geology of India, 2nd edn., p. 125), and Suess (Denkschr. 

 kais. Akad. d. Wissensch. Wien, math. nat. CI., vol. lxi, p. 439) 

 to correlate the lower Productus limestone with the upper car- 

 boniferous rather than with permo-carboniferous beds. In 

 the meantime Tschernyschew called attention to the strongly 

 marked affinities of the faunae of the middle Productus lime- 

 stone and the Artinskian stage. On palaeontological grounds 

 he tried to prove that the entire middle Productus limestone 

 ought to be synchronised with the Artinskian strata of Russia. 



" In admitting this homotaxis I merely followed the almost 

 unanimous judgment of European geologists. The equiva- 

 lence of the Chitichun limestone to the Virgal and Kalabagh 

 beds in the Salt Range having been clearly demonstrated, the 

 necessity of correlating it with the Artinskian stage of Russia 

 was obvious. 



" I have been convinced of the incorrectness of this correla- 

 tion both by the recent reports of Dr. Noetling on the classi- 

 fication of the Productus limestone and of the Ceratite forma- 

 tion in the Salt Range, and by my own examination of the 

 fossil materials collected by Walker" (pp. 53-54). 



" I do not, however, believe that the Chitichun limestone 



