SG Heritage Dictionary

Acephala [Noun plural] Webster's Dictionary 1913

That division of the Mollusca which includes the bivalve shells, like the clams and oysters; -- so called because they have no evident head. Formerly the group included the Tunicata, Brachiopoda, and sometimes the Bryozoa. See Mollusca.

Acephala Encyclopedia Britannica

ACEPHALA, a name sometimes given to a section of the molluscous animals, which are divided into encephala and acephala, according as they have or want a distinctly differentiated head. The Acephala, or Lamellibranchiata, as they are also called, are commonly known as bivalve shell-fish.

9th ed. Encyclopædia Britannica, vol. 1, p. 92
[45 words — estimated reading time: 1 minute]

Acephalan [Adjective] Webster's Dictionary 1913

Belonging to the Acephala.

Acephalan [Noun] Webster's Dictionary 1913

Same as Acephal.