94 
BULLETIN OF THE LABORATORIES 
minute forms, apparently chiefly in the form of casts, among these a 
number of gasteropoda. 
Gasteropoda. 
I. 
Cyclonema bilix. 
Conrad (sp.). 
^ H. 
Trochonema nana. 
. n. sp. 
III. 
Raphistoma afhnis, 
n. sp. 
IV. 
Pleurotomaria inexpectans. 
Hall and Whitfield. 
V. 
Cyclora alta. 
n. sp. 
VI. 
Strophostylus cyclostomus. 
. Hall. 
VH. 
Platyostoma Niagarense, 
Hall. 
VIII. 
Bucania exigua. 
n. sp. 
IX. 
Bellerophon fistello-striatus, 
n. sp. 
The 
Gasteropoda of the Clinton Group, 
identified with previously 
described forms, are too few to form any great basis of comparison, 
stratigraphically. Cyclonema bilix ranges from the Lower Silurian into 
the Upper. Stivphostyhis cyclostomus is found also at Waldron, Indi- 
ana. Flatyostoma Niagarense differs in size and expansion at the ap- 
erture from typical specimens, but its connection with them seems 
undoubted. At any rate its deviation from the typical forms is far 
less than the var. trigonostoma of Meek, and all these forms are typi- 
cal of the Niagara. 
genus cyclonema. Hall. 
1. Cyclonema bilix, Conrad (sp. ). 
Shell described from the Lower Silurian in Ohio Pal. Vol. 1. 
Locality and position. Centreville and Soldiers’ Home Quarries, 
frequent in the upper courses of the Clinton Group. 
GENUS TROCHONEMA, Salter. 
II. TrOCHONEMA NANA, Sp. 11. 
{Plate XIF, Fig. i6.) 
Shell oblong, the height about twice the breadth, in the specimen 
figured the carina being a little more prominent than is there indicated. 
Volutions about three, increasing rapidly in size, the last disproportion- 
ately so, forming the larger bulk of the shell, almost equaling two- 
thirds the height. Shell thin ; it is impossible to trace the suture line. 
