^Cinereous^: Ash-gray; having the color of wood-ashes. ^Cirri^, plural of ^Cirrus^: Filamentous appendages. ^Columella^: An upright pillar in the center of most of the univalve shells, round which the whorls are convoluted. ^Concrescent^: Growing together; uniting. ^Cordate^: Heart-shaped. ^Costæ^, plural of ^Costa^: Ridges of a shell. ^Crenulated^: Having a series of notches; marked as with notches, as the indented margin of a shell. ^Crystalline style^: A transparent gelatinous substance of unknown function, which fills, at times, the stomach-parts of certain mollusks. ^Ctenidia^, plural of ^Ctenidium^: Gills, or breathing-organs, adapted to water-respiration. [pg303] ^Decussated^: Crossed; intersected. ^Dextral^: Having the aperture on the right side of the shell when the apex is upward. ^Epidermis^: The horny coating or outer skin of some shells. ^Foot^: The ventral surface of the body on which the animal rests or moves. ^Fossette^: A little hollow or pit. ^Fuscous^: Brown tinged with gray; swarthy. ^Fusiform^: Tapering both ways from the middle. ^Lamelliform^: Lamellate in structure; disposed in leaf-like layers. ^Lingual ribbon^: The chitinous band of teeth, or rasp, borne upon the odontophore; the radula. ^Lunule^: An impressed area just below the beaks of bivalve shells. ^Mantle^: A fleshy or membranous outgrowth of the outer body-wall; also called /pallium/. ^Mantle cavity^: The space between the mantle and the body. ^Monomyarian^: Having one adductor muscle, as an oyster. ^Nephridium^: The renal organ of mollusks, corresponding to kidneys in vertebrates. ^Node^: A knob or protuberance; also a notch in the margin. ^Odon´tophore^: The lingual ribbon bearing chitinous teeth. ^Oper´culum^: A horny or shelly plate which serves to close the aperture of the shell when the animal is retracted. ^Osphra´dia^, plural of ^Osphradium^: Olfactory or water-testing organs. ^Otocyst^: The cavity, or cyst, which contains the essential parts of an organ of hearing. ^Pallial line^: The impression or mark made by the mantle, or pallium, on the inner surface of a bivalve shell. ^Pallial sinus^: A notch or recess of the pallial line; the scar of the siphon. ^Papillaceous^: Warty; studded with bosses; having excrescences. ^Perios´tracum^: Same as /epidermis/. ^Per´istome^: In zoölogy, mouth-parts in general; in conchology, the margin of the aperture of the shell. [pg304] ^Porcelanous^: Resembling porcelain. ^Rad´ula^: Same as /lingual ribbon/. ^Reticulated^: Having distinct lines or veins crossing like a network; covered with netted lines. ^Sculpture^: Elevated or impressed marks on the surface; markings resulting from irregularity of surface; tracery. ^Sinistral^: Having the aperture of the shell at the left; opposite of /dextral/. ^Sinuate^: Curved in and out; wavy. ^Siphon^: A tubular fold, or prolongation of the mantle forming a tube. ^Spire^: All the whorls of a spiral univalve, above the first large body-whorl.