The Collaborative International Dictionary
Polythalamous
Polythalamous \Pol`y*thal"a*mous\, a. [Poly- + Gr. ? a chamber.] (Zo["o]l.) Many-chambered; -- applied to shells of Foraminifera and cephalopods. See Illust. of Nautilus.
Wiktionary
polythalamous
a. (context zoology English) Having many chambers.