OPERCULUM

(Lat.), n. n. Op(o2p)-u6rk(e11rk)'u!1l(u4l)-usm- (u4m). From operire, to cover. Fr., opercule, plateau strie (2d def.). Ger., Klappdeckel (1st def.), ringfdrmiger Lappen (1st def.), cuticuldrer Rahmen (2d def.), Deckel (3th def.), Deckel chen (5th def.). Syn.: bright border (2d def.). Lit,, a lid or flap. 1. A group of small convolutions situated at the angle formed by the two limbs of the Sylvian fi ure and concealing the insula. [I, 6.] 2. Of Engelrnann, the highly refractive portion of the free end of a ciliated cell, composed of the pedicles connecting the cilia with the intracellular fibres. Everth. Marchi, and others consider it merely a differentiated portion of the cell through which the cilia project. [I, J | See also Cuticular LAYER. 3. In fishes, the chain of flat bones covering the gills, consisting of the inter operculum and the opercular. pre opercular, and subopercular bones. [B,28(o 27) L 14 207] 4. In the Mollusca, a horny or shelly plate developed on the hinder part of the foot, serving to close the aperture of the shell when the animal is retracted within it. [B. 28 (a, 27).J 5. A lid. such as that of the pitcher-plant; especially the top of a capsule that separates transversely by an even line. [B, 1, 19, 123, 291 (a, 35).] See Opercular BONE. O. ciitis. See EPIDERMIS. O. ilei. See Ileo ccecal VALVE. -O. laryiigis. See EPIGLOTTIS. O. lobi superior is. See O (1st def.). O. naris, O. nasale. In birds, the nasal scale: the roofing of the external nostrils. [L, 343.] O. occipitale. Of Gratiolet, a detached portion of the occipital lobe in apes [I 17 (K).] O. oculi. The eyelid. [F.] O. sellee. See DIAPHRAGM A hypnphyseos. [s. 154]