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 striae, at the sections 

 enlarged ; fissure rather large, oblong, inclined ; margin 

 minutely crenulate. 



Long. diam. .4, Transv. 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. grwca (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 grwca being in pairs. 



