The Collaborative International Dictionary
Somatocyst
Somatocyst \So"ma*to*cyst\, n. [Gr. sw^ma, sw`matos, body + ky`stis a bladder.] (Zo["o]l.) A cavity in the primary nectocalyx of certain Siphonophora. See Illust. under Nectocalyx.
Wiktionary
somatocyst
n. (context zoology English) A cavity in the primary nectocalyx of certain Siphonophora.