Shell not covered by the mantle margin, elongated oval, surface with scaly radial ribs; hole almost central, fairly large, elongate, margin somewhat elevated only posteriorly.

Apex subcentral, the perforation or orifice large, sculpture of imbricate radial ribs. The shell is crenulate at the ends within, the posterior margin slightly elevated. Soft parts are too large to be completely concealed by the shell. West American species have been reviewed by McLean (1967).