2ob NORTH-CAROLINA GEOLOGICAL SURVEY. 



This species is common in the miocene marl of North- 

 Carolina. It is also living upon the coast, but is more abun 

 dant, according to Dr. Gould, north of Cape Cod than south 

 of it. 



NATICA DUPLICATA. SAY. FlG. 150. 



Shell thick, ovate ; spire somewhat prominent and pyrami 

 dal by the compression of the whirls; and surface marked 

 by faint revolving lines; the lines of growth more distant; 

 umbilicus partially closed by a thick dense callus. 



FIGS. 150. 



NATICA. (Fig. 151.) 



Shell thick, spire depressed ; umbilicus perfectly closed by 

 a thick rough callus, which extends to the angle where it be 

 comes much thickened ; suture distinct. It agrees with the 

 clausa in part, but it is a much larger shell, being one inch 

 and eight-tenths in diameter. Fossils answering in size to 

 the clausa exist in the miocene marl on the Cape Fear 

 river. 



