Source : Webster's Revised Unabridged Dictionary (1913)

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