212 



Cerithium — continued. 



thiara. . turreted, rather cylindrical ; whirls crowned with 



tubercles, flat beneath ; the lip alated — f inch. 



mutahile. . three transverse strise on each whirl, the lower whirl 



with the upper stria tuberculated stronger than the others, 



upper whirl with the strise all alike — 1 j inch. 



semicoronatum. . turreted ; three granular striae on each whirl, 



the uppermest thickest ; a plait on the columella — If inch. 



cinctum. . conical, turreted ; three granular striae, rather equal 



in size ; a plait on the columella — If inch. 

 plicatum. . turreted, subcylindrical ; whirls granulated longi- 

 tudinally — 1 inch. 



conoideum. . short, conoidal, three or four rows of granulae on 

 each whirl — 1| inch. 



confluens. . turreted, with three transverse granulated keels, the 

 lowest the largest, granulae confluent — f inch. 



davits. . subulate ; two or three transverse granular striae, ver- 

 tically confluent ; base short and twisted — f inch. 



baccillum. . subulate, with eight or nine unequal obscure granular 

 striae — | inch. 



scahrum. . pyramidate ; echinated with two dentated keels, the 

 lower the largest — f inch. 



(isperellum. . conical, with two dentated keels, teeth very small 

 — var. ? — small. 



turritellatum. . turreted ; whirls convex, with three transverse 

 striae, and vertical bowed ribs — 1 inch. 



mitra. . conical, with four vertical striae, crossed by small gra- 

 nular ribs — small. 



pleurotomoides. . conical, turreted, with two rows of obtuse 

 tubercles ; a notch in the right lip — small. 



involutum. . conical, turreted ; turns smooth, imbricating ; colu- 

 mella twisted — 1 inch. 



tuber culosum. . turreted ; two rows of tubercles, the upper 

 largest, the lower margins crenulated — 15 inch. 



bicarinatum. . turreted, with subangulated keels ; four trans- 

 verse striae at the base — f inch. 



trochleare. . conical, subturreted ; two transverse keels, raised 

 and dentated, crossed by vertical ribs, giving an alveolated 

 appearance — sm all . 



trochiforme. . conical, short ; striae obsolete ; longitudinal ribs 

 — ^very small. 



muricoides. . conical, ventricose ; tubercular and granular striae ; 

 whirls convex — | inch. 



purpura. . conical, short ; transversely striated, and distinctly 

 tuberculated — var. ? — ~ inch. 



conoidale. . short ; the whirls flat, with unequally truncated 

 and sub tubercular striae — small. 



subulatum. . turreted, with noduliform ribs and transverse obso- 

 lete striae ; opening oblong. 



lapidorum. . turreted ; whirls convex, subtubercular in the 

 middle ; bowed vertical ribs, nearly obsolete — 1^ inch. 



