The Collaborative International Dictionary of English v.0.48:

Purparty \Pur"par`ty\, n. [OF. pourpartie; pour for + partie a
   part; cf. OF. purpart a respective part.] (Law)
   A share, part, or portion of an estate allotted to a
   coparcener. [Written also purpart, and pourparty.]
   [1913 Webster]

         I am forced to eat all the game of your purparties, as
         well as my own thirds.                   --Walpole.
   [1913 Webster]