Theca

||The"ca (?), n.; pl. Thecæ (#). [L., fr. Gr. ? a case to put anything in. See Tick a cover.] 1. A sheath; a case; as, the theca, or cell, of an anther; the theca, or spore case, of a fungus; the theca of the spinal cord.

2. (Zoöl.) (a) The chitinous cup which protects the hydranths of certain hydroids. (b) The more or less cuplike calicle of a coral. (c) The wall forming a calicle of a coral.