Wentletrap

from The Collaborative International Dictionary of English v.0.48

Scalaria \Sca*la"ri*a\, n. [L., flight of steps.] (Zool.)
   Any one of numerous species of marine gastropods of the genus
   {Scalaria}, or family {Scalaridae}, 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}.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Wentletrap \Wen"tle*trap`\, n. [D. wenteltrap a winding
   staircase; cf. G. wendeltreppe.] [Obs.]
   Any one of numerous species of elegant, usually white, marine
   shells of the genus Scalaria, especially {Scalaria pretiosa},
   which was formerly highly valued; -- called also {staircase
   shell}. See {Scalaria}.
   [1913 Webster]