What is "scalaria"

Scalaria \Sca*la"ri*a\, n. [L., flight of steps.] (Zo["o]l.) Any one of numerous species of marine gastropods of the genus Scalaria, or family Scalarid[ae], 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.