INTRODUCTION 
5 
The prominent exposures thus worked belong to the Beech River forma- 
tion of the Brownsport group as designated by Pate and Bassler in their paper 
already mentioned, which they further ’ subdivided into three zones called in 
ascending order Coccocrinus zone, Troostocrinus zone and Eucalyptocriniis zone. 
Of these the last, or upper, zone was by far the most important, the greater part 
of the crinoids having come from it. The other two are chiefly characterized 
General Section Tennessee, etc. Niagaran 
Tennessee 
Other Areas 
Europe 
Devonian 
Helderbergian 
Linden 
Decatur limest. 
Lobelville, coral zone 
Louisville Is. 
Kentucky, Ind. 
1 
Bob, limest. and shale 
o 
o. 
c 
Eucalyptocrinus zone, 
shale 
d 
§ 
<L) 
be 
c 
iU 
03 
(5 
-C 
a; 
QJ 
Troostocrinus zone, 
shale and limest. 
.2 
u 
'(ri 
o3 « 
bjO 
m 
Coccocrinus zone, 
shaly limest. 
Cedarville dol. 
Ohio 
S 
Dixon, shale and red limest. 
Racine dol. 
Illinois ' 
Lego, limest. 
Hopkinton dol. 
Iowa 
Waldron, shale 
Indiana 1 
Laurel, massive limest. 
C ! 
Indiana 
t 
Osgood, shale and limest. 
Rochester shale 
New York 
by the forms from which their names are given. Above the shales is a consider- 
able thickness of the Decatur limestone, which yielded only a few specimens 
here, but at a locality along the bluffs of the Tennessee river some remarkably 
distinct forms were obtained. At other places in the immediate vicinity the lower 
Niagaran formations occur, from Osgood to Dixon, so that the principal mem- 
bers are represented in their proper sequence within a short distance. 
To facilitate reference to the horizons mentioned in the descriptions, I give 
above the general section of the Silurian formations of Tennessee as deter- 
mined by Pate and Bassler, together with the equivalents which may enter into 
the discussions. 
