from the GNU version of the Collaborative International Dictionary of English
- n.pl. A large division of Mollusca, including all except the bivalves; -- so called because the head is distinctly developed. See Illustration in Appendix.
from The Century Dictionary and Cyclopedia
- A prime division of mollusks, including those with a head, generally provided with tentacles, eyes, and a mouth armed with jaws, as gastropods, pteropods, and cephalopods: same as Cephalophora, 1, or Encephala: the opposite of Acephala.
Sorry, no etymologies found.