abactinal, a. Zool.
(ˌæbækˈtaɪnəl, ˌæbˈæktɪnəl)
[f. L. ab away from + actinal.]
Remote from the actinal area; pertaining to that part of the surface of a radiated animal which is opposite to the mouth, e.g. the apex of a sea-urchin, or upper surface of a star-fish. See actinal.
| 1857 L. Agassiz Contrib. Nat. Hist. America IV. 376 I have called this side..the oral or actinal area, and the opposite side the aboral or abactinal area. 1864 A. Agassiz in Reader No. 85, 204/2 The spines on the abactinal area. 1881 Mackintosh in Nature No. 628, 41 The abactinal system and ambulacral plates of a Cidarid combined with the thin test and hollow spines of a Diadema. |