Zool. [f. Gr. ἀμφί on both sides + δίσκος a round plate.] Peculiar asteroid spicules, resembling two toothed wheels united by an axle, which form a layer surrounding the gemmules of sponges. (Nicholson.)
1867. J. Hogg, Microsc., II. ii. 389. Remains of the dead sponge, empty gemmule cases with their amphidiscs.
1877. Huxley, Anat. Inv. Anim., iii. 118. Nothing is left but the envelope of keratose, with imbedded amphidisks, disposed perpendicularly to its surface.
