Pallial chamber

from The Collaborative International Dictionary of English v.0.48

Pallial \Pal"li*al\, a. [L. pallium a mantle. See {Pall}.]
   (Zool.)
   Of or pertaining to a mantle, especially to the mantle of
   mollusks; produced by the mantle; as, the pallial line, or
   impression, which marks the attachment of the mantle on the
   inner surface of a bivalve shell. See Illust. of {Bivalve}.
   [1913 Webster]

   {Pallial chamber} (Zool.), the cavity inclosed by the mantle.
      

   {Pallial sinus} (Zool.), an inward bending of the pallial
      line, near the posterior end of certain bivalve shells, to
      receive the siphon. See Illust. of {Bivalve}.
      [1913 Webster]