200 
PALEONTOLOGY OF NEW-YORK. 
than in the last species, but still rounded. The transverse fine striae, under the magnifier, 
give a kind of varicose appearance, being closely arranged and slightly arched between 
the longitudinal ones, following the oblique direction of the annulalions. The difference 
in the size of the longitudinal end transverse lines is a striking peculiarity of the species, 
rendering it readily distinguishable from the last. 
I have referred above to the 0. calamiteum of Munster, which, however, is from the 
higher silurian or devonian rocks, from which circumstance alone it is proper to presume it 
distinct from this one. The figure of Portlock corresponds in some degree with our species, 
but is represented with two or three finer longitudinal strife between the larger ones, while 
the transverse striae are as strong as the fine longitudinal ones ; in which characters, the 
one under consideration is quite different. M. de Verneuxl has represented the O.calamiteus 
as destitute of transverse striae ; though the one referred to that species by D’Archiac and 
de Verneuil, cited above, has transverse striae. 
The species under consideration is not only quite distinct from 0. tubicinella of Sowerby, 
but from all the species in our higher strata, though having some resemblance to them. 
Fig. 2 a, b. View of two individuals, showing the annulations and longitudinal strice. 
Fig. 2 c. Transverse section of b. 
Fig. 2 d. Portion of the surface enlarged. 
Position and locality. In the lower shaly strata of the Trenton limestone at Middleville, 
Turin and Lowville. A fragment or impression of the same species has been found at an 
exposure of the Trenton limestone one mile east of Albany, which was incorrectly figured 
On Plate VII. (See page 35). {State Collection .) 
262. 15. ORTHOCERAS BILINEATUM, var. a. 
Pn. XLIII. Figs. 3 a , b , c , d . 
This variety differs from the typical forms, in the absence of the intermediate finer 
longitudinal striae ; the single series, which is pretty constant, corresponds in distance to the 
coarser ones in the other specimens. A careful examination of several specimens, however, 
has shown an occasional deviation from this rule, and smaller striae are sometimes present. 
In other characters, it is not essentially different from the last, and therefore can scarcely 
constitute a distinct species. 
Fig. 3 a. A fragment of this variety. 
Fig. 3 b. Transverse section, slightly compressed, showing the siphon. 
Fig. 3 c. An enlarged portion of the surface. 
Fig. 3 d. A fragment denuded of the shell, showing the lines of septa which do not correspond to the 
annulations. 
Position and locality. Same with the preceding. 
