The Collaborative International Dictionary of English v.0.48:

Succursal \Suc*cur"sal\, a. [Cf. F. succursale. See Succor, n.
   & v. t.]
   Serving to aid or help; serving as a chapel of ease;
   tributary. [R.]
   [1913 Webster]

         Not a city was without its cathedral, surrounded by its
         succursal churches, its monasteries, and convents.
                                                  --Milman.
   [1913 Webster]