The Collaborative International Dictionary
Perisarc
Perisarc \Per"i*sarc\, n. [Pref. peri- + Gr. ?, ?, flesh.] (Zo["o]l.) The outer, hardened integument which covers most hydroids.
Wiktionary
perisarc
n. (context zoology English) The outer hardened integument that covers most hydroids.