IOWA ACADEMY OP SCIENCES. 
29 
where the beds have always been regarded asnon fossiliferons, 
an extensive fauna has been lately disclosed.* Its facies is 
very decidedly Devonian. 
The thin, soft, earthy limestone (No. 12), which is nine feet 
in thickness at Louisiana, is believed to be the attenuated por- 
tion of the Chouteau limestone, though it is so closely associated 
with the lower beds of the Burlington, that it might be termed 
the Chouteau-Burlington. Toward the southwest the undoubted 
Chouteau limestone, before leaving Pike county, has a thickness 
of thirty feet, and still farther in the same direction in central 
Missouri the thickness increases to over 100 feet. 
The lower Burlington limestone is separated upon lithological 
and faunal grounds into five zones, and the rj|)per Burlington, as 
represented in the section, into three zones. 
Nearly all of the strata are highly fossiliferous. The vertical 
section and the exposures are so extensive for a single locality 
that the facilities for determining the exact range of the various 
faunas stand unrivalled in the whole region. Moreover, a key 
to the stratigraphy of the entire province is furnished. Owing 
to unusually favorable opportunities for forming extensive 
collections of the fossils which are representative of the 
different horizons, the results are very complete. The deter- 
mination of the faunal zones and their most important relation- 
ships as bearing upon the stratigraphy of the region are 
therefore of great interest. The subjoined tabular arrangement 
displays the more salient features in the distribution of the 
faunas. 
TABLE SHOWING VERTICAL RANGE OF FOSSILS. 
SPECIES. 
1 J Hudson. 
Niagara. 
Hamilton. 
Louisiana. | 
Hannibal. 
d 
<D 
O 
Xi 
o 
13 
Lower Burlington. 
Upper Burlington. 
2 
3 
4 
5 
6 
T 
8 
9 
10 
11 
13 
14 
15 
16 
17 
18 
19 
20 
Plants: 
Plumulina gracilis (^^huniard) 
X 
Taonurus crassus? (Hall) 
X 
Sponges: 
Stromatopora sp? 
X 
X 
PalEeacis enormis (Meek & WortheD) . 
Conopterium effusum, Winchell 
X 
X 
X 
X 
X 
Corals: 
Amplexus blairi. Miller 
X 
X 
X 
X 
Amplexus sp? — 
X 
X 
. .. 
*Iowa Geol. Sur., vol. Ill, p. 80, 1893. 
