perigone

n. [ Pref. peri- + Gr. &unr_; productive organs. ] 1. (Bot.) (a) Any organ inclosing the essential organs of a flower; a perianth. (b) In mosses, the involucral bracts of a male flower. [ 1913 Webster ]

2. (Zool.) A sac which surrounds the generative bodies in the gonophore of a hydroid. [ 1913 Webster ]