348 
I\AL7EUNT0L0GY OF FEW YORK. 
Test thin, having a thickness of .35 mm. Surface marked by fine, con¬ 
centric lines of growth, crossed by indistinct, longitudinal ridges. 
A specimen, preserving a portion of the chamber of habitation, with twelve 
air-chambers, has a length of fifty-five mm., of which twenty mm. pertain to 
the outer chamber. 
This species somewhat resembles G. tumidum , but may be distinguished by the 
position of the plane of greatest transverse section, and the less tapering apical 
portion of the tube. In general form and size it is related to G. Conradi, but 
in the latter species the endogastric curvature, the point of greatest gibbosity, 
and the crenulations at the base of the chamber of habitation are very distinc¬ 
tive. The specimens, as occurring in the soft carbonaceous shales and in the 
coarser beds, present slight differences, which appear to be due principally to 
the mode and condition of preservation. 
Formation and localities. In the shales of the Hamilton group, at Pratt’s Falls, 
Onondaga county, and Cazenovia, Madison county, N. Y. 
Gomphoceras Conradi. 
PLATE XLVI, PIGS. 1-3. 
C-fomphoceras (Apioceras) Conradi, Hall. Thirteenth Rep. N. Y. Slate Cab. Nat Hist., p. 106. I860. 
“ “ “ “ Fifteenth Rep. N. Y’. State Cab. Nat. Hist., pi. 8, fig. 8. 1S62. 
Cyrtoceras Conradi , Hall. Illustrations of Devonian Fossils: Cephalopoda, pi. 47, figs. 1 , 2, 11. 1876. 
Shell small, clavate, nearly straight, curvature of the dorsal side rather more 
than the ventral, making the curvature endogastric. From the slope of the 
sides of the chamber of habitation, the indication is that of an exogastric 
curvature. Transverse section broadly oval, slightly flattened on the dorsal 
side. Tube enlarging gradually from the apex to a point nearly on the 
centre of the chamber of habitation, thence contracting gradually to the 
aperture. Apical angle about 20°. Apex acute. 
The length of the chamber of habitation is nearly equal to the lateral 
diameter of the tube at the last septum. Ventral side more convex than the 
dorsal; btffh sides slope gradually to the aperture, and show a flattened area 
extending from the base midway to the aperture. Tube marked by a slight 
