The Collaborative International Dictionary of English v.0.48:

Winkle \Win"kle\, n. [AS. wincle.] (Zool.)
   (a) Any periwinkle. --Holland.
   (b) Any one of various marine spiral gastropods, esp., in the
       United States, either of two species of Fulgar (Fulgar
       canaliculata, and Fulgar carica).
       [1913 Webster]

   Note: These are large mollusks which often destroy large
         numbers of oysters by drilling their shells and sucking
         their blood.
         [1913 Webster]

   Sting winkle, a European spinose marine shell (Murex
      erinaceus). See Illust. of Murex.
      [1913 Webster]