GASTEROPODA. 
115 
distant striae. Approaching the anterior and lateral margins, the stronger 
sharp striae become obsolete, leaving the surface marked only by the 
simple striae of growth. 
This is a small species, attaining about half an inch in length. It is quite 
rare: no specimen seen has shown the interior of the aperture, or the colu- 
mellar lip. It may be readily distinguished from any other described in the 
formations under consideration by its general form, the simple, sharp, trans¬ 
verse striae, and the comparatively wide dorsal band, which is marked by striae 
as on other parts of the surface. 
In general form and surface-markings this species corresjDonds with B. 
vasulites of Montfort, as figured by Ferussac and d’Orbigny, but differs in the 
open umbilicus as well as in other details. It may also be compared with 
B. hiulcus of Martin. In form it is quite similar to the young of B. Leda; but 
in that one the revolving striae are always present, and usually more conspicu¬ 
ous than the transverse striae. 
Formation and localities. A single specimen has been found in the shales of 
the Hamilton group in each of the following localities : Near Norton’s Landing 
on the east side of Cayuga lake; below Monteith’s Point on Canandaigua lake; 
and at York in Livingston county, N. Y. 
r ‘ J 
Bellerophon rotalinea, n. sp. 
PLATE XXVI, FIG. 8. 
Shell small, discoid. Volutions gradually expanding to near the aperture; 
umbilicus open; sides of the exposed volution depressed towards the back, 
and marked by a revolving sinus, leaving a prominent dorsal ridge. 
Surface marked by distinct and sharply defined revolving striae, which are 
distant from each other about twice their width. No concentric strise 
are visible on the specimen examined. 
This small species is quite distinct from any other known in these forma¬ 
tions. The discoid form with open umbilicus, revolving striae, and absence, so 
far as visible, of all other surface-markings, are characteristic features. It has 
