The Collaborative International Dictionary of English v.0.48:

Euthyneura \Eu`thy*neu"ra\, n. pl. [NL., fr. Gr. ? straight + ?
   a nerve.] (Zo["o]l.)
   A large division of gastropod molluske, including the
   Pulmonifera and Opisthobranchiata.
   [1913 Webster]