a) Pertaining to the side or surface around the mouth in an animal that has radial symmetry such as a starfish.
The so-called mouth is always placed at one of these poles, and from it radiate the most prominent organs, in consequence of which I have called this side of the body the oral or actinal area ...
b) Pertaining to the axis of rotational symmetry in radiate animals.
[Professor Agassiz] gives the names of two axes of the animals; that around which the motion of the animal occurs is the actinal axis ...
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