The Collaborative International Dictionary of English v.0.48:

Phalangious \Pha*lan"gi*ous\, a. [L. phalangium a kind of
   venomous spider, Gr. fala`ggion, fr. fa`lagx a spider. Cf.
   Phalanx.] (Zool.)
   Of or pertaining to Phalangoidea.
   [1913 Webster]