GASTEROPODA. 
35 
greater than the width exposed ; body-volution moderately ventricose and 
rounded above; the periphery a little contracted vertically, and the lower 
side rounded and expanded more abruptly towards the aperture, gently 
depressed towards the centre, which is partially umbilicate. Aperture 
nearly circular. 
Surface marked by strong revolving striae, which are crossed by fine and less 
conspicuous concentric striae, giving sometimes a denticulate character at 
the crossing of the two series. Shell of moderate thickness. Suture 
neatly defined, not canaliculate. 
This species is less distinctly conical above than the P. Hebe —the volutions 
being rounded without the angle on the periphery. It was originally described 
as Pleurotomaria, which it resembles in form, but has no proper peripheral band. 
Other specimens coming under examination, it was properly referred to the 
genus Cyclonema, and thus published as a new species in Illustrations of Devonian 
Fossils, as cited above. A comparison with the. original of P. Doris has proved 
the identity of the two. From the examination of a single imperfect specimen 
from the Schoharie grit, it seems probable that the figures given are from 
specimens which are more or less accidentally depressed, and that the spire is 
more elevated than represented. 
Formation and locality. In the Schoharie grit of the Upper Helderberg 
group, at Schoharie, N. Y. The occurrence of the species in the Corniferous 
limestone (. Fifteenth Rep. State Cab.) has not been verified by farther investigation. 
Cyclonema lirata. 
PLATE XII, FIGS. 27-20. 
Cyclonema lirata, Hall. Descriptions of New Species of Fossils, etc., p. 19. 1S61. 
“ “ “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 47, pi. 5, fig’. 15 (not 16). 1862. 
“ “ “ Illustrations of Devonian Fossils : Gasteropoda, pi. 12. 1876. 
Shell robust, subdepressed-conical. Volutions about four, subangular, the 
last one becoming very ventricose, flattened from the suture to the first 
carinate elevation on their upper side, and marked by moderately elevated 
