GASTEROPODA. 
107 
of growth, the sinuosity in the anterior side of the peristome has been very 
deep and acute ; but at a later period, this character has become gradually less 
extreme, and the strim of growth make a distinct curve on that part of the 
shell. 
This species bears much resemblance to the Bellerophon Murchisoni of 
d’Orbigny, but is more robust, with a greater width on the posterior side of 
the aperture and a wider umbilicus. 
Formation and localities. In the shales of the Hamilton group, at Hamilton 
and Pratt’s Falls, in Madison county; on the east shore of Cayuga lake, near 
Norton’s Landing; and at York in Livingston county. 
Bellerophon brevilineatus. 
PLATE XXVI, FIGS. 5, 6 7. 
[?] Bellerophon brevilineatus, Conrad. Jour. Acad. Nat. Sci. Phil., vol. 8, p. 269, pi. 16, flg-. 6. 
Shell thin, ovoid, trumpet shaped, the outer volution rapidly enlarging 
expanded at the aperture and sinuate in front; the dorsum elevated into 
a distinct carina, and limited on each side by a sinus, which separates it 
from the body of the volution. Umbilicus open and comparatively wide. 
Surface marked by simple concentric striae, which proceed pretty directly from 
the umbilicus, and gently arching over the sides of the volution, where 
they are often interrupted or obsolete, bend abruptly backward into the 
sinus, and thence sharply arch over the carinate dorsum. 
In many specimens the strirn are interrupted, becoming obsolete beyond 
the middle of the sides of the volution, and do not continue into the sinus 
between the body of the shell and the carina, though reappearing upon the 
dorsum. 
This feature corresponds essentially with the description and figure of B. 
brevilineatus , as given by Mr. Conrad, which is as follows: 
“ Discoidal, tapering gradually to a very acute periphery ; volutions exposed; 
from the margin of the umbilicus radiate short lines, less in length than half the 
width of the large volution.” 
