bursa
From ZooTerms (Dictionary of Invertebrate Zoology)
bursa (noun; plural bursae; Latin bursa, purse): 1. Any pouch or sac, a sac-like cavity.
2. A lateral cuticular extension adanal, or surrounding the tail of male nematodes and acanthocephalans that functions as claspers or guides during copulation; has also been applied by various workers to all caudal alae.
3. (Echinodermata: Crinoidea) In Ophiurida, formed by infoldings of the body wall of the oral disc to either side of the base of each arm, functioning in gas exchange or as bursal slits
See also: bursa copulatrix.
