GASTROPODA— CAPU LID M. 



713 



CVIII. Calyptr^a Lam. (Galerus Gray.) 

 Thin, conical spiral shells, with the last whorl greatly expanded, 

 bearing a wide aperture with flat periphery ; whorls often spinose. 

 Cretacic-Recent. 



359. C. centralis Conrad. (Fig. 1029, a-c.) 



Oligocenic— Miocenic. 



Conical, with apertural rim projecting beyond the last whorl ; 

 surface smooth except for a few irregular spiral lines and growth 

 lines. 



Chipolan of Gulf States ; St. Mary's of Maryland. 



360. C. aperta Solander. (Fig. 1029, d.) Miocenic- 



Fig. 1029. a-c, Calyptrcea centralis, nat. size ; d, C. aperta, X 



(Md. Survey. 



Large, gibbous, with regularly enlarging spirals, the later ones 

 strongly spinose. 



Choptank and Calvert formations of Maryland ; Shiloh marls 

 of New Jersey. 



CIX. Crepidula Lam. 



Slipper-shaped, with beak nearly or quite marginal, and often 

 enrolled. The elongate aperture is partly covered 

 by a platform or thin lamellar expansion of the 

 inner lip. Cretacic-Recent. 



361. C. lirata Conrad. (Fig. 1030.) Eocenic. 

 Beak much produced, strongly curved to side 



and forward, with subspiral apex ; form narrow, 

 elongate and deep ; surface with irregular striae or 

 costae and transverse wrinkles. 



Claibornian of Alabama, very common. 



362. C. plana Say. (Fig. 103 1, a, b.) 



Oligocenic-Recent. 

 Flat ; apex marginal, not enrolled ; shell elon- 

 gate; platform covering about half the length of shell. 



Fig. 1030. 

 Crepidula lirata. 

 (After Conrad.) 



