O*per"cu*lum (?), n.; pl. L.
Opercula (#), E. Operculums (#).
[L., a cover or lid, fr. operire to cover.] 1.
(Bot.) (a) The lid of a pitcherform
leaf. (b) The lid of the urnlike capsule
of mosses.
2. (Anat.) (a) Any
lidlike or operculiform process or part; as, the opercula of a
dental follicle. (b) The fold of
integument, usually supported by bony plates, which protects the
gills of most fishes and some amphibians; the gill cover; the gill
lid. (c) The principal opercular bone in
the upper and posterior part of the gill cover.
3. (Zoöl.) (a)
The lid closing the aperture of various species of shells, as
the common whelk. See Illust. of Gastropoda.
(b) Any lid-shaped structure closing the
aperture of a tube or shell.
