The Collaborative International Dictionary of English v.0.48:

Cockal \Cock"al\, n. [Etymol. uncertain.]
   1. A game played with sheep's bones instead of dice. [Obs.]
      [1913 Webster]

   2. The bone used in playing the game; -- called also huckle
      bone. [Obs.] --Nares.
      [1913 Webster]

            A little transverse bone
            Which boys and bruckeled children call
            (Playing for points and pins) cockal. --Herrick.
      [1913 Webster] Cockaleekie