Keyes — Devonian & Carboniferous in Upper Mississippi Valley. 369 



From a consideration of both tabular arrangements the 

 followinor oreneral conclusions are deduced : — 



1. The most marked change in the succession of faunas in 

 the entire sequence of rocks commonly know as the lower 

 Carboniferous or *' Subcarboniferous," as represented along 

 the Mississippi river, is at the base of the Chouteau limestone 

 (limited). At this horizon there is so great a faunal hiatus 

 that there is scarcely a species that is common to the beds on 

 either side. 



2. That instead of the so-called Kinderhook containing in 

 its fauna a mingling of Devonian and Carboniferous types, 

 there are really two faunas that are perfectly distinct, well 

 defined, and do not merge into each other. The one is charac- 

 teristically Devonian in character, and the other as strikingly 

 Carboniferous in its general aspect. 



3. The basal line of the lower Carboniferous or Missis- 

 sippian series is the base of the Chouteau limestone, and the 

 lowest member of the fourfold series contains only one 

 formation, instead of the three heretofore commonly ascribed 

 to it. 



4. The early reference of a part of the so-called Kinder- 

 hook or "Chemung" to the Devonian was correct in fact, 

 though done entirely through erroneous correlations and a 

 misconception of the real facts. 



5. That the evidence afforded by the faunas of the region 

 is in close accord with the facts obtained regarding discordant 

 sedimentation and the stratigraphical and lithological charac- 

 ters of formations themselves. 



Issued June 1, 1897. 



