The Collaborative International Dictionary of English v.0.48:

Anthobranchia \An`tho*bran"chi*a\, n. pl. [NL., fr. Gr. 'a`nqos
   flower + ? gills, n. pl.] (Zool.)
   A division of nudibranchiate Mollusca, in which the gills
   form a wreath or cluster upon the posterior part of the back.
   See Nudibranchiata, and Doris.
   [1913 Webster]