cephalata

from The Collaborative International Dictionary of English v.0.48

Cephalata \Ceph`a*la"ta\, n. pl. [NL., fr. Gr. kefalh` head.]
   (Zool.)
   A large division of Mollusca, including all except the
   bivalves; -- so called because the head is distinctly
   developed. See Illustration in Appendix.
   [1913 Webster]