94 CONTRIBUTIONS 
CLASS MOLLUSCA. 
ORDER GASTEROPODA. 
FAMILY CALYPTRACIANA.: => 
GENUS FISSURELLA. Lamarck. 
F. Claibornensis. Plate 3. Fig. 74. 
Description. Shell elliptical, on the back convexly 
conical, thin ; ribs numerous, cut by striz, at the sections 
enlarged ; fissure rather large, oblong, inclined; margin 
minutely crenulate. ' 
Long. diam. .4, Transy. diam. .3, Height .2, of an inch. 
Observations. One specimen and a fragment are all I 
have seen from this locality. It has some resemblance to. 
F. greca (Lamarck), but is more elevated, has smaller ribs, 
and is not ovate, but elliptical. It differs, too, in the crenu- 
lation of the margin, those of the graca being in pairs. 
