The soft body is elongated and spiral. The foot almost always considerable and subelliptical. It is shielded or two-lobed before, emarginated behind, bearing an operculum. The mantle is simple and forms a thin-edged flap over the branchial cavity. It is provided with a branchial siphon, projecting, thick, very long and dorsal, issuing from the emargination at the base of the shell. The head is rather thick, furnished with two conical, depressed tentacles supporting the eyes upon the outer side, (sometimes the eyes do not exist, but this case is extremely rare) . The mouth is provided with a retractile trunk, armed with minute teeth. The radula acts as a rasp. The sexes are separate. The love dart of the male is considerable, without an exterior furrow at its base.