410 
PALAEONTOLOGY OF NEW YORK . 
by obscure or obsolete transverse annulations on tbe chambered portion. 
A single specimen shows obscure, wide, flattened longitudinal folds over the 
convex side of the chambered portion of the volution, but they are not con¬ 
tinued over the chamber of habitation. This part of the surface is some¬ 
times very distinctly marked by longitudinal, impressed striae, which are 
about the same distance apart as the narrow depressions between the wide, 
obscure plications. 
Another fragment of the chambered portion of a larger shell shows similar 
but much more distinct plications upon the surface, and is doubtfully referred 
to the same variety of form. 
A single large individual sIioavs obsolescent, longitudinal folds over the sur¬ 
face of the cast of the chamber of habitation.' The largest specimen has had 
a diameter of about ninety-free mm., and a specimen slightly compressed, 
near the distal termination of the chambered portion, has a transverse 
diameter of about fifty mm. 
This species, or variety of form, is closely related to, if not specifically iden¬ 
tical with N. liratus. It Avas originally separated from N. liratus , on account of 
the absence of the radiating costee upon the centre of the concave dorsal side 
of the shell, as Avell as upon the convex portion of the outer chamber. With 
the present material for study and comparison, it has appeared necessary to 
recognize the distinction in order to reconcile the marked differences observed 
in the specimens. It may be remarked, that of those referred to N. Urdus, one 
presents a lateral view, and the other is crushed in a lateral direction. All 
the specimens referred to N. sublirdus, with one exception, are crushed in a 
Amntro-dorsal direction, and this fact may have some connection with the 
apparent differences. 
This form may be compared with N. pinguis, de Koninck. 
Formation and locality. In the compact shales of the Hamilton group, at 
. Earlville, Madison county, N. Y. 
