%pyxidium%

‖n.; pl. Pyxidia [ NL., fr. Gr. &unr_;, dim. a &unr_; a box. See Pyx. ] (Bot.) (a) A pod which divides circularly into an upper and lower half, of which the former acts as a kind of lid, as in the pimpernel and purslane. (b) The theca of mosses. [ 1913 Webster ]