30 C. ScJiuchert — Russian Carboniferous and Permian. 



These make it clear that this is not the normal marine fauna that 

 continues the Paleozoic sequence into the Mesozoic. This point, 

 however, will be discussed on a later page (see " Conclusions," 

 paragraph 2). 



In regard to the Russian faunas the author states : — 

 " I wish to call attention to the decided differences which 

 make their appearance in the fauna of the Omphalotrochus 

 horizon when contrasted with the type of that of Miatschkowo 

 [near Moscow ; also see the following table for stratigraphic 

 position], and on the other hand the great resemblance of the 

 brachiopod fauna of the Schwagerina zone to that of the higher 

 lying Permo-Carbon (the Artinsk deposits CPg and the Lime- 

 stone-dolomite CPc). In the lower Permian fauna of Russia we 

 have already noted a decided reduction in Brachipoda, if not 

 in quantity, at least in variety of species ; and in the still 

 higher horizons of the Russian Permian, the total number of 

 Brachiopoda is not more than 40 species [this number has 

 reference to all areas correlated with the typical Perm 

 area]. Entire groups of forms . . . that give a decided aspect 

 to the fauna of the Upper Carboniferous Artinsk, and the 

 Limestone-dolomite beds, are completely unknown in the Per- 

 mian sediments of Russia and west Europe. Some of these 

 groups therefore attract our attention because they are foreign 

 to the Permian deposits, yet in the Mesozoic (Trias and Jura) 

 they attain an extended' development. On the other hand, 

 others belong to such original types as the Lyttoniidse, Teguli- 

 fera, and Orthotichia, forms that give a decided character to 

 the upper Paleozoic, and, so far as our knowledge goes, com- 

 pletely disappear with the Permian epoch [of western Europe]. 

 From a biological standpoint there can be no doubt that our 

 Upper Carboniferous brachiopod fauna has the facies of a 

 younger type than the Permian, and that in its entirety it has 

 a more decided Mesozoic impress than that of the [Russian] 

 Permian following, which when compared with the other 

 shows atavistic trends [see note 6]. As it is my opinion that 

 this atavism finds its proper explanation in the physico-geo- 

 graphic conditions of the Permian sea, I hold that it is not 

 superfluous to direct special attention to this fact, and thereby 

 to moderate the tendency of some geologists, who in their 

 determination of the age of this or that fauna depend mainly 

 upon the biological peculiarities and not infrequently leave out 

 of consideration the possible explanation that the biological 

 differences between two synchronous or at least closely adjoin- 

 ing faunas are partially due to facies and chorological causes" 

 (pp. 663-4). 



" Although the data presented regarding the distribution 

 of Upper Carboniferous deposits in the region of European 



