MARINE MOLLUSCA OF THE UNITED STATES. U 



Synopsis of Genera. 



Shell turreted, manj-whorled, generally reticulate or granular -with indis- 

 tinct varices ; canal produced in front and slightly recurved ; columella 

 thickened, with a callosity at the hind part. Ceritiiium, Adanson. 



Aperture with a slight canal in front, not produced or recurved ; inner lip 

 acute, not reflexed or expanded. Bittium, Leach. 



Shell sinistral ; aperture round, produced anteriorly into a closed, tubular 

 canal, sometimes with a posterior, closed canal. Triphoris, Deshayea. 



Genus CERITHIUM, Adanson. 

 Hist Nat. Senegal. 153. 1757. 

 1. C. ferrugineum, Say. Fig. 126. 

 Am. Conch., t, 49, f. 3. 1832. 

 Shell oblong-conical, with longitudinal ribs rendered nodulous 

 by revolving elevated strife ; ribs about twenty on the body-whorl, 

 almost interrupted by the interstices of the striae; striae about 

 seven with intermediate smaller ones on the body-whorl, and but 

 three on the second whorl ; volutions seven, suture inconspicuous ; 

 aperture oblique, oval, whitish within; labrum slightly thickened 

 on the exterior margin and with obsolete impressed lines on the 

 inner side corresponding with the exterior striae ; color ferrugi- 

 nous. 



North Carolina to Florida. 



Genus BITTIUM, Leach. 

 Gray, Zool. Proc. London. 1847. 

 This group includes several northern forms, smaller than the 

 typical Cerites, and resembling dextral Triphores; they range from 

 low water to eighty fathoms. 



1. B. nigrum, Totten. Fig. 12Y. 



(Pasithea) test. juv. Am. Journ. Sci., xxvi. 369, t. 1, f. 7. 1834. 

 Ceritiiium reticulalum, Totten, ibid, xxviii. 353, f. 8. 1835. 

 Cerithnim Sayi, Menke, Gould, Invert. Mass. 1st Edit. 278, f. 183. 1841. 



Shell small, acute, conic, thin. Whorls from six to eight with 

 a distinct shoulder formed by a series of granules. Surface granu- 

 lar from the crossing of slightly elevated folds with elevated spiral 

 lines ; about twenty of these ribs, which disappear on the lower 

 half of the body-whorl leaving there only about six slightly elevated 

 revolving lines. Suture deeply impressed. Aperture about a 

 fourth of the length of the shell, elongate, subovate, acutely an- 



