\Cys*tid"e*a\ (s?s-t?d"?-?), n. pl. [NL., fr. Gr. ????
a bladder, pouch.] (Zo["o]l.)
An order of Crinoidea, mostly fossils of the Paleozoic rocks.
They were usually roundish or egg-shaped, and often
unsymmetrical; some were sessile, others had short stems.