螅鞘; 螅鞘
Hydrotheca \Hy`dro*the"ca\, n.; pl. L. {Hydrothec[ae]}, E. {Hydrothecas}. [NL., fr. E. hydra + Gr. ? a box.] (Zo["o]l.) One of the calicles which, in some Hydroidea (Thecaphora), protect the hydrants. See Illust. of {Hydroidea}, and {Campanularian}.