450 
PALAEONTOLOGY OF NEW YORK. 
removal of the fossil, and is a cast from the inside of the shell, which preserves 
only slight evidence of surface strife, and the nodes represented are such only 
as would be preserved on a cast of the interior. 
Until recently only two specimens of this species were known to me, and 
these, preserving little more than one volution, showed no evidence of septa or 
other indications of being a Cephalopod, and it was referred with doubt to the 
genus Porcellia, in the Illustrations of Devonian Fossils published in 1876. 
Further collections have added great numbers of individuals, but without 
giving satisfactory evidence of the entire structure. Of several hundred speci¬ 
mens only three present external evidence of the septate character, and the 
greater proportion of the specimens of which sections have been made, preserve 
only the chamber of habitation, with a simple curved septal termination, or 
with one or two septa and air-chambers. 
The species has been found only in some shaly and pyritiferous calcareous 
layers in the Marcellus shale, and so far as known has a very limited vertical 
and horizontal distribution. It is associated with Styliola and Tentaculites 
figured on plate 31 A of this volume. 
Formation and locality. In a calcareous band in the Marcellus shale at Cherry 
Valley, N. Y. 
Goniatites bicostatus. 
PLATES LXXII, FIGS. 6-10; LXXIV, FIG. 1. 
Groniatitts bicostatus, Hall. Geolog-, Surv. of N. Y.: Rep. Fourth District, p. 245, fig. 8. 1843. 
“ <• “ Thirteenth Rep. N. Y. State Cab. Nat. Hist., p. 103, figs. 19, 20. 1860. 
“ “ “ Illustrations of Devonian Fossils: Cephalopoda, pi. 72, figs. 6-10. 1876. 
Shell depressed-spheroidal in the young state, becoming discoidal in its advanc¬ 
ing growth, with the sides more or less convex, and often flattened from 
compression, and the periphery regularly rounded. The proportions of 
thickness and lateral diameter, in a specimen which is somewhat compressed, 
are as one to three and a half. This proportion varies according to the 
stage of growth, accidents of imbedding, and mode of preservation. 
Volutions about three or more, partially exposed; gradually enlarging 
