The Collaborative International Dictionary of English v.0.48:

Sea crawfish \Sea" craw"fish`\ Sea crayfish \Sea" cray"fish`\
   (Zool.)
   Any crustacean of the genus Palinurus and allied genera, as
   the European spiny lobster (Palinurus vulgaris), which is
   much used as an article of food. See Lobster.
   [1913 Webster]