The Collaborative International Dictionary of English v.0.48:

Cryptobranchiata \Cryp`to*bran`chi*a"ta\ (kr?p`t?-bra?`k?-?"t?),
   n. pl. [NL., fr. Gr. krypto`s hidden + L. branchia a gill.]
   (Zool.)
   (a) A division of the Amphibia; the Derotremata.
   (b) A group of nudibranch mollusks.
       [1913 Webster]