UPPER CARBONIFEROUS 137 



considerable differences found between the Russian Permian and the 

 Kansas Permian faunas would, according to this hypothesis, be 

 explained as due to the play of like conditions upon unlike organic 

 bases, the pre-Permian faunas in the one region having changed, 

 and those in the other having remained unchanged. But this appears 

 to me improbable. One would hardly expect that the Pennsylvanian 

 fauna would remain static during so long a period in which such 

 important faunal changes were taking place in adjacent areas. Nor 

 would one expect that Permian conditions would be inaugurated 

 simultaneously in two areas so far apart, whose biologic histories are 

 so different, and which were separated by an area having a more or 

 less independent set of faunal phenomena. Finally, if the Kansas 

 Permian is Permian, what is the fauna from the Oklahoma red beds, 

 obtained at a considerably higher horizon, and showing a consider- 

 ably different facies ? It does not seem probable to me therefore that 

 the Kansas Permian and the Russian Permian were contemporaneous. 



An extreme interpretation of the resemblances and differences 

 noted in comparing the successive faunas of Russia and eastern North 

 America would result in correlating the Kansas Permian not with the 

 Russian Permian, as in the last hypothesis, but with the Moscovian. 

 In this case the quasi-Permian facies of the upper beds of Kansas 

 would be accounted for as showing the yield of an unlike and older 

 fauna to Permian conditions which arrived on this continent at a 

 much earlier period than in Russia, just as in the previous case the 

 differences of the same fauna from the typical Permian would be ex- 

 plained as the opposite or complementary phenomenon, the resistance 

 of an unlike fauna to Permian conditions. Probably the ultimate 

 fact lies somewhere between these two extreme interpretations of the 

 evidence. 



I do not wish to appear as having a rooted aversion to admitting 

 the Permian age of the higher faunas of the Kansas section. My 

 position is merely that of a skeptic and the only point upon which 

 I feel justified in assuming the positive attitude of dogmatism is that 

 the evidence at present is so inconclusive that dogmatism itself would 

 be ill-advised. At present, it is true, the weight of evidence, as pre- 

 sented by invertebrate paleontology, appears to me to be in favor of its 

 pre-Permian age. This view has much of precedent against it. 



