The Collaborative International Dictionary of English v.0.48:

Pricksong \Prick"song`\ (?; 115), n. [See Prick, v. t., 4.]
   Music written, or noted, with dots or points; -- so called
   from the points or dots with which it is noted down. [Obs.]
   [1913 Webster]

         He fights as you sing pricksong.         --Shak.
   [1913 Webster]