Annulosa

Group of bilateral and segmented Invertebrates, including the Scolecid a, An arthropod a, and Arthropod a. Annulus. Elastic ring of thick-walled cells which embraces the sporange in certain ferns, and by parting, causes its rupture at maturity, thus expelling the spores. Also, a layer of cells around the operculum of a mo sporange. Also, the portion of the volva of a mushroom remaining attached to the stalk.