Pellibranchiata

from The Collaborative International Dictionary of English v.0.48

Pellibranchiata \Pel`li*bran`chi*a"ta\, n. pl. [NL., fr. pellis
   garment + branchia a gill.] (Zool.)
   A division of Nudibranchiata, in which the mantle itself
   serves as a gill.
   [1913 Webster]