Source : Webster's Revised Unabridged Dictionary (1913)

Scallop \Scal"lop\ (?; 277), n. [OF. escalope a shell, probably
   of German or Dutch origin, and akin to E. scale of a fish;
   cf. D. schelp shell. See {Scale} of a fish, and cf.
   {Escalop}.] [Written also {scollop}.]
   1. (Zo["o]l.) Any one of numerous species of marine bivalve
      mollusks of the genus Pecten and allied genera of the
      family {Pectinid[ae]}. The shell is usually radially
      ribbed, and the edge is therefore often undulated in a
      characteristic manner. The large adductor muscle of some
      the species is much used as food. One species ({Vola
      Jacob[ae]us}) occurs on the coast of Palestine, and its
      shell was formerly worn by pilgrims as a mark that they
      had been to the Holy Land. Called also {fan shell}. See
      {Pecten}, 2.

   Note: The common edible scallop of the Eastern United States
         is {Pecten irradians}; the large sea scallop, also used
         as food, is {P. Clintonius, or tenuicostatus}.

   2. One of series of segments of circles joined at their
      extremities, forming a border like the edge or surface of
      a scallop shell.

   3. One of the shells of a scallop; also, a dish resembling a
      scallop shell.

Source : WordNet®

Pecten irradians
     n : a small scallop inhabiting shallow waters and mud flats of
         the Atlantic coast of North America [syn: {bay scallop}]