188 
PALAEONTOLOGY OF NEW YORK. 
A, figs. 11-14, are here recognized under this specific term, while figures 15 
and 16 may perhaps be only varieties of the same species: the first of these 
preserving obscure transverse markings, while the latter in one part is indis¬ 
tinctly cancellated. 
Formations and localities. In the upper part of the Genesee slate near Bristol 
Centre, Ontario county, and in other localities in central and western New York; 
in the Cashaqua shales of the lower part of the Portage group on the banks 
of the Genesee river, and in the same geological position near Ithaca, N. Y. 
CoLEOLUS CRENATOCINCTUM, n. Sp. 
PLATE XXXII, FIGS. 1, 2, 3, AND PLATE XXXII A, FIGS. 3, 4. 
Shell an extremely elongated cylindro-conical tube, which tapers very gradually 
from the larger extremity towards the acute apex. Section circular. 
Shell substance comparatively thick and strong. 
Surface annulated by narrow crenulated rings, which appear to be directly 
transverse. 
The largest diameter of the imperfect specimen, figure 1, plate XXXII, 
is five millimetres, and at the smaller end approximating three and one-half 
millimetres, with a length between these points of about four centimetres. 
Another fragment in the same rock measures fully seven millimetres m 
diameter. The longest specimen observed, and which, in the absence of 
surface-markings, I have referred with doubt to this species, is about three and 
a half inches in length. 
This species occurs in the higher beds of the Upper Helderberg group, and 
in some localities it is quite abundant. The specimens, figures 1 and 2, plate 
XXXII, are in a decomposing chert, and the shell is silicified; a single 
fragment only preserving the surface-markings, as represented in fig. 2. The 
directly transverse aspect of the annulations may be due to the position of 
the specimen, though we have no evidence of their oblique direction. 
In the specimen, figure 1, plate XXXII, the shell is shown to have been 
replaced by layers of siliceous matter. The comparative diameter of the 
