Hydrotheca \Hy`dro*the"ca\, n.; pl. L. {Hydrothec[ae]}, E.
{Hydrothecas}. [NL., fr. E. hydra + Gr. ? a box.] (Zool.)
One of the calicles which, in some Hydroidea (Thecaphora),
protect the hydrants. See Illust. of {Hydroidea}, and
{Campanularian}.
[1913 Webster]