The Collaborative International Dictionary of English v.0.48:

Seawan \Sea"wan\, Seawant \Sea"want\, n.
   The name used by the Algonquin Indians for the shell beads
   which passed among the Indians as money.
   [1913 Webster]

   Note: Seawan was of two kinds; wampum, white, and
         suckanhock, black or purple, -- the former having
         half the value of the latter. Many writers, however,
         use the terms seawan and wampum indiscriminately.
         --Bartlett.
         [1913 Webster]