MARINE MOLLUSCA OF THE UNITED STATES. 77 



3. S. Grcenlandica, Chemnitz. Fig. 139, 



S. subulata, Couthouy, Bost. Journ, Nat. Hist., ii. 93, t. 3, f. 4. 1838. 

 8. planicosta, Kieuer, Iconog., t. 7, f. 21. 1838. 



Shell tapering to a fine point, imperforate; whorls nine or ten, 

 contiguous, slightly convex, with eight to fifteen stout compressed 

 oblique ribs, with intervening coarse rounded vertical ridges, and 

 seven or eight revolving striae ; the ribs not ending abruptly at 

 the suture, but flowing along the sutural region to the preceding 

 ones ; aperture nearly circular, bordered by a rib which is emar- 

 ginate at the base; operculum horny, shining. 



Length 25, diara. 8.75 mill. 



Animal 3'ellowish-gray with whitish spots; mouth rather large, 

 rounded, corrugated. 



Arctic America (Eur.). 



4. S. ANGULATA, Say. Fig. 140. 



(S. clathrus, Linn, var.), Amer. Conch., iii. t. 27. 1831. 



5. Humphreysii, Kiener, Iconog. 1838. 



Shell conic, turreted, imperforate, white, immaculate; whorls 

 six to eleven, touching each other only by the ribs, but with a 

 very narrow interval; ribs nine to each volution, prominent, sim- 

 ple, a little oblique, somewhat recurved, and with a more or less 

 obvious, obtuse angle or shoulder above, near the suture ; aper- 

 ture suborbicular ; base a little angulated ; labium distinct. 



Length 15 to 20 mill. 



Described by Mr. Say as a doubtful variety of 5. clathrus., from 

 which it is distinct. 



New England to Florida. 



5. S. TURBiNATA, Conrad. Fig. 141. 



Journ. Philad. Acad. Nat. Sciences, vii. 263, t. 20, f. 26. 1837. 

 Shell with the bodj^-whorl dilated ; ribs lamellar, strong, very 

 prom.nent, slightly reflected, terminating above in a prominent 

 angle ; color white. 



Bea7(fort, Nortli Carolina. 



6. S. MULTISTRIATA, Say. Fig. 142. 



Amer. Conch., iii. t. 27. 1831. 

 Shell conic, turreted, tapering to an acute apex, white, immacu- 

 late, imperforate ; whorls about eight, in contact ; costte regular, 

 simple, not reflected, equidistant, moderately elevated ; spaces 

 between the costse with very numerous, approximate, equidistant, 



