periproct

periproct (noun; Greek peri, around; proktos, the anus): 1. The distal piece or segment of the body containing the anus.

2. (Annelida: Oligochaeta) The pygomere or pygidium.

3. (Arthropoda) see telson.

4. (Echinodermata) The circular membrane containing the anus, surrounded by a varying number of embedded plates.