Source : Webster's Revised Unabridged Dictionary (1913)

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}.