40 
IOWA ACADEMY OP SCIENCES. 
species which comprise a lower fauna in the midst of a higher. 
The most striking features in the vertical distribution of the 
fossils shown in the table given are: (1) The upper fauna 
nowhere extends beneath the base of the Chouteau (No. 12) 
and the lower fauna nowhere rises above the same line; (2) 
all the species belonging to the fauna beginning in the Chou- 
teau extend upward into the Burlington; (3) while in the 
Burlington many new forms appear there is no immediate 
replacement of the older forms; (4) the many new species 
which appear in the second bed of the Burlington (No. 14) are 
largely so-called Kinderhook forms, not altogether from the 
Chouteau, but from the limestones which occur just beneath 
the Burlington limestone at the city of Burlington. 
Prom a consideration of both tabular arrangements the fol- 
lowing general conclusions are deduced: 
1. The most marked change in the succession of faunas in 
the entire sequence of rocks commonly known 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 not merging into each other. The one is charac- 
teristically Devonian in character and the other as strikingly 
Carboniferous in its general facies. 
3. That the basal line of the Lower Carboniferous or Mis- 
sissippian series is the base of the Chouteau limestone and the 
lower member of the four-fold series contains only one forma- 
tion instead of the three heretofore commonly ascribed to it. 
4. That the early reference of a part of the so-called 
Kinderhook or “Chemung” to the Devonian was correct in 
fact, though made through erroneous correlations. 
5. That the evidence afforded by the faunas of the region is 
in close accord with the facts obtained regarding discordant 
sedimentation, and the strati graphical and lithological charac- 
ters of the formations. 
