The Collaborative International Dictionary of English v.0.48:

Myxocystodea \Myx`o*cys*to"de*a\, n. pl. [NL., fr. Gr. ? mucus +
   ? a bladder.] (Zool.)
   A division of Infusoria including the Noctiluca. See
   Noctiluca.
   [1913 Webster]