Acephala

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Lamellibranchia \La*mel`li*bran"chi*a\, Lamellibranchiata
  \La*mel`li*bran`chi*a"ta\, n. pl. [NL. See {lamella}, and
     {Branchia}, {Branchiate}.] (Zool.)
     An earlier name for the class of Mollusca including all those
     that have bivalve shells, as the clams, oysters, mussels,
     etc., now called {Pelecypoda} or {Bivalvia}.


     [1913 Webster +PJC]
  
     Note: They usually have two (rarely but one) flat,
           lamelliform gills on each side of the body. They have
           an imperfectly developed head, concealed within the
           shell, whence they are called {{Acephala}}. Called also
           {Conchifera}, and {Pelecypoda}. See {Bivalve}.
           [1913 Webster]

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Acephala \A*ceph"a*la\, n. pl. [NL., fr. Gr. ?, adj. neut. pl.,
     headless. See {Acephal}.] (Zool.)
     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}.
     [1913 Webster]