28 AMERICAN MARINE CONCHOLOGY. 



more or less tumid ; columella smooth, inner lip expanded ; outer lip 

 usually thin, smooth internally. Operculum lamellar, nucleus external. 



BucciNUM, Linn. 



Shell ovate, small, few-whorled ; aperture moderate ; coluraellar lip callous, 

 expanded, forming a tooth -like projection near the anterior canal. Oper- 

 culum ovate, nucleus apical. Nassa, Lam. 



Shell striated, imbricated, or tuberculated ; spire short ; aperture large, 

 with a slight oblique channel in front ; inner lip much worn and flat- 

 tened. Operculum lamellar, nucleus external. Purpura, Lam. 



Shell very small, limpet like ; with a large aperture, channelled in front, 

 and a minute lateral spire. No operculum. Pedicularia, Swains. 



Shell oblong, small, thick, with a long, narrow aperture ; outer lip thick- 

 ened, especially in the middle, dentated ; inner lip crenulated. Opercu- 

 lum very small, lamellar. Columbella, Lam. 



Shell obconic, ventricose, with irregular varices ; spire short ; aperture long 

 and narrow ; outer lip reflected, denticulated ; inner lip spread over the 

 body-whorl ; canal sharply recurved, producing a varix on the back of 

 the shell. Operculum small, elongated ; nucleus in the middle of the 

 straight inner edge. Cassis, Lam. 



Shell oval, ventricose, thin, spirally furrowed, without varices ; spire small ; 

 aperture very large ; outer lip crenated. No operculum. 



DoLiuM, Lam. 



Shell long turreted, dextral, many-whorled, granulated ; aperture subro- 

 tund ; inner lip broadly reflected ; outer lip acute, arcuated and produced 

 anteriorly ; aperture anteriorly siuuated ; canal short. Operculum cor- 

 neus, concentric ; apex terminal. Cerithiopsis, Forbes & Hanley. 



Shell long pointed, many-whorled ; aperture small ; canal short. Oper- 

 culum pointed, nucleus apical. Acus, Humphrey. 



Shell cylindrical, polished ; spire very short, suture channelled ; aperture 



long, narrow, notched in front ; columella callous, striated obliquely ; 



body -whorl furrowed near the base. No operculum. 



Oliva, Lam. 



Genus BTJCCINUM, Linnaeus. 

 Syst. Nat., edit. x. 734. 1758. 

 Tritonium, O. Fabricius (not Link), Faun. Groon. 395. 1780. 



Shell ovate or oblong, covered by a honiy epidermis ; spire 

 elevated, apex acute; aperture large, oval, emarginate in front; 

 canal wide, truncated, dorsally more or less tumid ; columella 

 smooth ; inner lip expanded ; outer lip usually thin, smooth in- 

 ternally. 



Animal with eyes on slight eminences at the outer bases of the 

 tentacles. 



The genus contains few species, of Arctic distribution. 



