What is "pallial chamber"

Pallial \Pal"li*al\, a. [L. pallium a mantle. See Pall.] (Zo["o]l.) 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.

Pallial chamber (Zo["o]l.), the cavity inclosed by the mantle.

Pallial sinus (Zo["o]l.), an inward bending of the pallial line, near the posterior end of certain bivalve shells, to receive the siphon. See Illust. of Bivalve.