/ozi'a Carboniferous Formations — Sardeson. 307 
thin and bound by vesiculose structure at the base, thicker and 
free within, not always reaching the centre. The vesiculose 
peripheral region varies from thin to one-half the radial 
length in thickness. In general the thickened septa tend to 
fill the apex solid, but with age the vesiculose region widens 
and the septa also becomes thinner. The surface is marked by 
numerous fine transverse wrinkles and more or less distinct 
vertical striations. 
Keye's remarks [op. cit.) upon the relation of Com- 
pophyllum and Cyathophyllum as shown in this species seem 
well taken. 
Specimens are found abundantly at Humboldt and Rut- 
land, Iowa. They are well preserved with the original filled 
by calcite and conspicuous cross sections look like small sliced 
lemons on the cliff walls. 
This fauna is not a complete one. That the number of 
species may be increased by continued search is suggested 
from the three species which are represented by only one, two 
and three specimens respectively, in my collection. The fauna 
morever has the aspect of a partial one in the absence of 
brachipods, crustaceans and echinoderms. The remains of 
such animals ought to be equally in evidence if they lived here 
at that time, and since the same species as those found are 
known elsewhere in association with such others, their absence 
is more remarkable than the occurrence of these. 
Indeed, the shells and coral are obviously such as may eas- 
ily have floated, and drifted hither, and thus have separated 
from the living fauna. It came probably from the west hence 
the presence of Euomphalus laxus. Th proof of such a 
theory and that of the Kinderhook age of the strata is not 
-undertaken, though of the latter there is in view the alter- 
native of Lower Burlington only, from evidence of fossils. 
Keyes reports E. springvalensiis and E. laxus ? from that horizon 
in Missouri (Mo. G«ol. Sur.. IV, 65) and there is probability 
that faunal studies on a scale large enough to comprehend the 
region from the Rocky mountains to Indiana may bring out 
the history and correlation more accurately than has been prac- 
ticable heretofore. 
The Saint Louis formation in some places fills cleft-like 
depressions in the Kinderhook limestone and the contact is ir- 
