UPPER CARBONIFEROUS 317 
similar conditions acting upon two unlike faunas might produce 
rather similar results. ‘The resulting faunas might be less diverse than 
the original ones. This is perhaps particularly true of conditions 
such as appear to have prevailed in the typical Permian, conditions 
hostile to marine life, hostile especially to the continuance of specialized 
types of life, at least of brachiopods. 
In the Kansas section we appear to have a single faunal sequence 
gradually passing to extinction but undergoing some minor modifica- 
tions in the process. The upper portion of the sequence is the Kansas 
Permian. We are told by those who are familiar with both, that 
Permian conditions are manifested in the so-called Permian sediments 
of the Mississippi Valley. I believe that there is no strictly Permian 
fauna in that area. ‘The question at issue is: Do the higher inverte- 
brate-bearing beds of the Kansas section represent Permian time ? 
On the assumption that such is the case, a comparison of the evolution 
of the faunas of the two continents is interesting. Let any one 
acquainted with our eastern faunas look over Trautschold’s mono- 
graph on the Moscovian fauna and he would exclaim at once, “This 
is our Pennsylvanian facies.” Let him next examine .Tscherny- 
schew’s monograph on the Gschelian brachiopods, and he would 
find that nothing at all comparable is known among the faunas of 
eastern North America. He would even find that the few Pennsyl- 
vanian species which Tschernyschew has recognized among the Gsche- 
lian brachiopods are wrongly identified. If he furthermore studies 
the scattered accounts of the Artinskian and Permian faunas I think, 
too, that he will find less resemblance between them and the Kansas 
Permian than has often been supposed. 
Apparently there was a basal generalized type of Upper Car- 
boniferous fauna distributed over both continents without any wide 
difference of facies—the Moscovian of Russia, the pre-Hueconian of 
western North America, and the early Pennsylvanian of eastern. 
Then changes occurred which brought about striking and similar 
modification in the faunas of western America and Russia, the Gsche- 
lian of Russia and the Hueconian of western North America. Then 
again other changes occurred which brought about a third modifica- 
tion, this time restricted to western America, or, at all events, not 
developed similarly there and in Russia. Meanwhile the fauna of 
