a. 离辐的, 无触角的

[ adj ]
(of radiate animals) located on the surface or end opposite to that on which the mouth is situated
<adj.all>

Abactinal \Ab*ac"ti*nal\ ([a^]b*[a^]k"t[i^]*nal), a. [L. ab + E.
actinal.] (Zo["o]l.)
Pertaining to the surface or end opposite to the mouth in a
radiate animal; -- opposed to {actinal}. ``The aboral or
abactinal area.'' --L. Agassiz.