Geol. [f. mod.L. cystidea, f. cystis: see CYST and -ID.] = CYSTID 1.
1862. Dana, Man. Geol., 398. Cystideans … became extinct in the beginning of the Devonian.
1876. Page, Adv. Text-bk. Geol., xii. 207. So may a cystidean … be considered a sea-urchin attached to the bottom by a similar jointed column.
