Peristome /(pē̇r"ĭ*stōm)/

Per·i·stome

Peristome

n.
  1. 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. (Bot.)
  2. The lip, or edge of the aperture, of a spiral shell. (Zool.)