154 PALEONTOLOGY OF NEW JERSEY. 
conical with a slightly anterior but nearly subcentral apex which is ele- 
vated above the margin equal to about one-third the length of the shell; 
sides and anterior end of the shell slightly concave between the apex and 
margin, and slightly convex along the posterior side. Surface marked by 
elevated, rounded, radiating costz, which are rather wider than the inter- 
spaces and gradually increasing in size toward the margin of the shell, but 
are constantly increased in number, both by bifurcation and by implantation. 
The radii are crossed by very fine concentric lines, but toward the margin 
of the shell these increase in strength so as to become distinct crenulations 
on the top of the radii, and are nearly or quite one-half as strong as the 
radii themselves. 
This shell has some peculiar features about it which makes me quite 
doubtful as to its true generic relations. In the first place, the substance 
of the shell is unlike that of a gasteropod, and appears almost as if it might 
have been phosphatic in nature. The apex of the specimen is worn away, 
and the substance of the shell partially exfoliated for some distance below, 
as well as being apparently partially replaced or infiltrated with iron in the 
condition of a sesquioxide. Ithas much the character of a Crania also, and 
I have been strongly inclined to consider it as one, especially as it appears 
to have been attached to another shell, Pecten, although this might also be 
the case, perhaps, with a gasteropod of the nature of Helcion, or more par- 
ticularly so of Hipponyx, to which genus it appears to have been referred 
by some one, I think by Mr. Conrad, in whose handwriting, apparently, 
the reference is made on the accompanying label. As it, however, is repre- 
sented only by a single specimen, and that one Dr. Morton’s type, I have 
not felt at liberty to manipulate it in any manner to ascertain its true nature. 
It agrees, as far as the specimen shows, with the genus to which I have 
referred it, except in its texture. So, for want of more definite evidence as 
to its true nature, I leave it as placed by D’Orbigny. 
Formation and locality: In the Lower Marls near Arneytown, New Jer- 
sey. The specimen is the property of the Acad. Nat. Sci., Phila. 
