operculigenous (operkulijenus)

[L. operculum, a lid, + gignere, genere, produce: see- genous.] Producing an operculum: specifically, noting the meta podium or posterior part of the foot of gastropods. operculigerous (ō-per-kū-lij'e-rus), a. [ operculum (6-pèr' kū-lum), n.; pl. opercula (-lä). [= F. opercule = Sp. opérculo = Pg. It. operculo, Operculum of Mo . times, the lid or top of certain circumsci ile capsules (pyxis), as in Portulaca, Plant a go, etc. (3) The conical limb of the calyx of Eucalyptus. See cuts under Ascidium and mo . (b) In zool.: (1) In conchology, a horny or shelly IMG:content-1744.png:[blocks in formation] plate secreted the operculige nous organ of gastropods and some other mol lusks, serving to close the aper ture of the shell when the ani mal is retracted. See cuts under Ampullariida doœæ. (2) In cirri. peds, as Balani dæ, the movable part of the rig id shell, which forms a flap cov ering the en trance to the mantle-cavity. (3) In Crustacea, the eighth pair of appendages of a king-crab, united together into a broad plate, the dorsal surface of which genital organs open, and which forms a flap covering the succeeding appendages of this division of the body. See Limulus. (4) In Polyzoa, as Chi los to mat a, that part of the ectocyst of the cell of the polypid which forms a movable lid shutting down upon the zoöid when the latter is withdrawn into its cell. (5) In ichthyology, the hindmost and uppermost bone of the opercular apparatus or gill-cover. See opercular apparatus, and also cuts under pal a to quadrate, Spatular i a, and teleost. (6) In ornithology: (a) The nasal scale; the small horny or membranous lid or flap which covers or closes the external nostrils of sundry birds. (8) The ear-conch or feathered flap which closes the ear of an owl. (7) In mammalogy, parts of the ear of an aquatic mammal, as a shrew or vole, so arranged as to act like a valve to prevent the entrance of water. (8) In entomology, one of two small pieces on the sides of the metathorax, covering the spiracles or breathing-orifices. Also called tegula and covering - scale. (9) In Arachnid a, one of the small scales covering the stigmata or breathing-orifices of a spider. They are distinguished as the branchial opercula, covering the openings of the branch iæ, and the tracheal opercula, nearer the base of the abdomen or sometimes at the end, covering the orifices of the tracheæ. The latter are often absent. (10) In Infusoria , the lid of the price of the icellidest of brain. lapping the gyri operti from above, and formed mainly by the pre central and post central gyri united below the end of the Rolandic or central fi ure. See cuts under cerebral principal covering of insula or Reil, over and gyrus.-Muricoid operculum. See muricoid. opere in medio (op'e-re in me'di-ō). [L.: opere, abl. of opus, work; in, in; medio, abl. of medius, middle. In the midst of (one's) work. opertaneous (op-er-tā'nē-us), a. [L. operta neus, concealed, hidden,