The Collaborative International Dictionary of English v.0.48:

Britzska \Britz"ska\ (br[i^]ts"k[.a]), n. [Russ. britshka; cf.
   Pol. bryczka, dim. of bryka freight wagon.]
   A long carriage, with a calash top, so constructed as to give
   space for reclining at night, when used on a journey.
   [1913 Webster]