The Collaborative International Dictionary of English v.0.48:

Acephalan \A*ceph"a*lan\, n.
   Same as Acephal.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Acephalan \A*ceph"a*lan\, a. (Zool.)
   Belonging to the Acephala.
   [1913 Webster]