THE RELATIONS OF SOME CARBONIFEROUS FAUNAS 25 



least, correspond to those of the Mississippi Valley, but person- 

 ally I know of no instance where a detailed correlation can con- 

 fidently be made. It is my hope and belief that these relations 

 can be determined with precision, and if it proves that the Rus- 

 sian investigator has had the clearness of vision to discern them 

 aright, all the greater should be his meed, because of the in- 

 tricacy which the question seems to present. 



The opinion has been expressed that the Pennsylvanian faunas 

 of eastern and western United States may belong in different 

 provinces, and that they are probably to some extent equivalent. 

 The belief is tentatively held that the highest of our Western 

 horizons are considerably younger than the highest known in- 

 vertebrate horizons of the East, those of the Kansas section, 

 for instance, which are characteristic of the so-called Permian 

 of the Mississippi Valley. In spite of the able pens which have 

 traversed this subject, the correlation of these beds is still one 

 of the unsettled problems of the American Carboniferous. If 

 the Capitan fauna is Permian, then certainly that of Kansas is 

 not, for 2 Carboniferous faunas could scarcely have less in 

 common. While it is possible that the so-called Kansas Permian 

 is a provincial phase of the Guadalupian, this is yet to be demon- 

 strated, and it is questionable whether for 2 faunas so essentially 

 unlike, even if proved to have been contemporaneous, the same 

 name could with propriety be used. On the assumption that 

 the Kansas beds are Permian, so closely are they connected, 

 faunally and stratigraphically, with those below, the term 

 Permian must be reduced to denominate a difference not much 

 greater than that between the Burlington and Keokuk, or else 

 most of the Kansas section must be placed in the Permian, a 

 disposition against which there is much evidence. It seems 

 probable that the Kansas Permian represents a faunal develop- 

 ment in a distinct province from that of the West, the Western 

 faunas being co-provincial with the typical Permian sea. The 

 equivalence of the Kansas Permian is not to be determined upon 

 the basis of a community of a few slightly differentiated long- 

 lived types, but must be worked out by a consideration of the 

 fauna as a whole and the facies which it receives from the 

 presence of a series of equivalent but probably not equal species. 



