204 
PALAEONTOLOGY OF NEW YORE. 
internal structure are distinctive features, as compared with other species in 
the same formation. The substance of the shell has been comparatively thin, 
and apparently hyaline, and from its mode of preservation, as well as from its 
peculiar form and characters, it may be inferred that the fossil belongs to the 
Pteropoda. The genus proposed for its reception may be characterized as 
follows : 
Fossil an obliquely conical tube or sheath, expanding from the apex more 
rapidly on one side, while the other maintains a nearly vertical line; 
the interior crossed by arching septal lines, which are unsymmetrical on 
the two sides of the axis or summit of the arch, and on the shorter side 
are recurved near their junction with the exterior shell; the septa crossed 
by longitudinal lines, which apparently penetrate the cavity, and give a 
cancellated aspect to the interior. Shell thin, translucent, and marked by 
lamellose lines of growth, subparallel to the septal lines. Aperture and 
complete form of shell unknown. 
Clathrocielia eborica, n. sp. 
PLATE XXXII, FIG. 10; and PLATE XXXII A, FIGS. 28, 29. 
The figures illustrate the only known form of the genus above described. 
The length of one specimen is over forty-six millimetres, and the apex is 
incomplete. The greatest width at the aperture, measured in a directly trans¬ 
verse line, is about twelve millimetres. 
Formation and localities. In the calcareous shale of the Hamilton group, east 
of Alden, Erie county, N. Y.; and in a calcareous band in the same shales, 
at Darien, Genesee county, N. Y. 
