peristome

n. [ Pref. peri- + Gr. sto`ma, sto`matos, mouth. ] 1. (Bot.) The fringe of teeth around the orifice of the capsule of mosses. It consists of 4, 8, 16, 32, or 64 teeth, and may be either single or double. [ 1913 Webster ]

2. (Zool.) (a) The lip, or edge of the aperture, of a spiral shell. (b) The membrane surrounding the mouth of an invertebrate animal. [ 1913 Webster ]