The Collaborative International Dictionary of English v.0.48:

Ampullaceous \Am`pul*la"ceous\, a. [L. ampullaceus, fr.
   ampulla.]
   Like a bottle or inflated bladder; bottle-shaped; swelling.
   --Kirby.
   [1913 Webster]

   Ampullaceous sac (Zool.), one of the peculiar cavities in
      the tissues of sponges, containing the zooidal cells.
      [1913 Webster] Ampullar