scalaria

from The Century Dictionary.

• noun A genus of holostomous ptenoglossate pectinibranchiate gastropods, typical of the family Scalariidæ; the ladder-shells or wentletraps.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) Any one of numerous species of marine gastropods of the genus Scalaria, or family Scalaridæ, having elongated spiral turreted shells, with rounded whorls, usually crossed by ribs or varices. The color is generally white or pale. Called also ladder shell, and wentletrap. See ptenoglossa, and wentletrap.