134 CHARLES S. PROSSER 



Carboniferous from the Carboniferous and Permian systems, is 

 important in this connection: 



Karpinsky and Tschemyschew, two authors, to whom the most detailed 

 studies of the Artinskian fauna are due, strongly advocate the distinction of the 

 permocarboniferous from carboniferous and permian systems, and are decidedly 

 averse to uniting it with either the one or the other. Tschemyschew especially 

 strongly combats the view of the majority of geologists who proposed to unite the 

 permocarboniferous with the permian, as a lower division of the system. Accord- 

 ing to him a separation of the permocarboniferous from the permian system is 

 demanded by the general aspect of the fauna, in which the carboniferous types 

 greatly predominate, chiefly among the brachiopoda. If it ought to be united 

 either with the carboniferous or permian system, in spite of its distinctly inter- 

 mediate position, it must necessarily be placed in the former, on the strength both 

 of the carboniferous character of its fauna and of historical priority, since the 

 Artinskian sandstone had been correlated with the carboniferous millstone-grit 

 of western Europe by Sir Roderick Murchison, who first introduced the name of 

 permian. 



Against the first argument the objection may be raised that notwithstanding 

 the prevalence of carboniferous types in the Artinskian fauna, the latter "marks 

 a very important moment in the history of development of organic remains, 

 namely, the first appearance of true ammonites with complicated sutures." Nor is 

 the large percentage of carboniferous types in the Artinskian fauna an astonishing 

 fact, in view of the absence of any break in the sequence of marine beds from the 



upper carboniferous to the true permian strata Bearing in mind the 



gradual passage from an upper carboniferous to a permian fauna through the 

 intermediate group of rocks, the question to be answered is, which consideration 

 is of the greater importance in defining the boundary between the two systems, 

 the appearance of a new group of cephalopoda, which become of an unparalleled 

 stratigraphical value in Mesozoic times, or the presence of a belated fauna, com- 

 posed of forms which are generally not well adapted for the characterization of 

 narrowly limited horizons. 



The majority of geologists have decided in favor of the first alternative. 

 Gumbel, Krasnopolsky, Kayser, Waagen, Credner, Munier-Chalmas and A. 

 de Lapparent, Freeh — to enumerate only a small number among them — are 

 unanimous in regarding the permocarboniferous as the lowest division of the 

 permian system. 



A discussion of the permocarboniferous problem from a historical point of 

 view leads to a similar result. This side of the question has been especially 

 treated by Freeh, whose reasoning I consider to be entirely justified.^ 



I "The Permocarboniferous Fauna of Chitichun," No. I, Mem. Geol. Surv. 

 India, ser. XV, "Himalayan Fossils," Vol. I, Pt. 3, 1897, pp. 87-89. This quotation 

 may also be found in an article by Professor Schuchert in Am. J our. Sci., 4th ser., 

 Vol. XXII, 1906, pp. 143, 144. 



