NORTH-CAROLINA GEOLOGICAL SURVEY. 265 



PLEUROTOMA ELEGANS. N. S. (Fig. 146.) 



Shell small, sub-turrited ; whirls, about nine, constricted 

 above, ornamented by numerous longitudinal ribs, and tra- 

 versed by many fine raised spiral lines, which become very 

 distinct upon the pillar lip. 



The spiral lines are very regular and equi-distant. The 

 body whirl has about sixteen ribs. Figure natural size. 



FIG. 148. FIG. 147. FIG. 145. FIG. 146. 



PLEUROTOMA TUBERCULATA. N. S. (Fig. 147.) 



Shell small, thick, sub-acute ; whirls, seven or eight ; apex 

 sub-tuberculated, constricted above, and traversed spirally by 

 rather coarse raised lines ; apex papillated, and the first whirl 

 is spirally lined, and without tubercles or short ribs. It is 

 more widely constricted than the preceding. 



PLEUROTOMA FLEXUOSA. N. S. (Fig. 148.) 



Shell small, thick, sub-turbinate ; whirls, seven or eight, 

 and ornamented by flexuose ribs, which extend across the 

 whirl; ribs alternating with those of the adjacent whirl. 

 There are about ten ribs belonging to the body-whirl. 



FAMILY NATICIDAE. 



The genus Natica belongs to a family of shells which is 

 characterised by a globular form, few whirls, or a low and 

 obtuse spire, a semilunar aperture, an acute outer lip, and an 

 umbilicus often covered, wholly or in part, by a thick cal- 

 lus. The species are all marine. 



NATICA HEROS. SAY. Fig. 149. 



Shell sub-globose, spire depressed, whirls four, convex ; 

 lines of growth obscure ; aperture, ovate ; umbilicus simple 

 and rather large. 



