Bimarginate, furnished with a double margin as far as the lip. Biradiate, having two rays. Bivalve, consisting of two valves or divisions. Blotched, spotted in an irregular way. Blunt, obtuse, opposed to acute. Borer, a piercer. Brinded, streaked. Bulging, gibbous, swollen out. Bullate, of a blistered appearance. Byssus, a beard, common in the Mytilus and Pinna. C. Calcareous, relating to lime, of a limy nature. Callosity, a protuberance. Callus, is composed of two short ribs, united at the base, and converging at the apex towards the hinder part of the shell. Campanulate, bell-shaped. Canaliculated, made like a pipe or gutter. Cancellated, longitudinally and transversely ribbed. Carinate, having a longitudinal prominence like the keel of a vessel. Carinated, keeled. Cartilage, a flexible fibrous substance by which the valves are united, situated near the beak. Cauda, the elongated base of the venter, lip, and columella. Cicatrix, the glossy impression in the inside of the valves, to which the muscles of the animal are affixed. Ciliate, edged with parallel hairs, bristles, or appendages, like the eyelids. Cinereous, of ash colour, of the colour of wood ashes. Clavate, club-shaped, thicker towards the top, elongated towards the base. Cochleæ, shells of one piece, univalves. Cochleate, twisted like a screw or the shell of a snail. Columella, the upright pillar in the centre of most of the univalve shells. Commissure, a joint or seam. Complicated, doubled together. Compressed, perpendicularly squeezed together, in opposition to depressed, which is horizontally flattened. Concamerated, arched over, vaulted. Concamerations, divided into compartments, as in the Nautili. Concave, hollowed out like a bowl. Concentric, running to a centre. Conchæ, shells consisting of two or more pieces or valves, bivalves, or multivalves. Cone, the form of a sugar-loaf. Confluent, running together. Conoid, a figure like a cone, sugar-loaf-shaped. Contorted, twisted, or incumbent on each other, in an oblique direction. Contracted, shortened, shrunk up. Convoluted, rolled upon itself, twisted spirally, like a piece of paper rolled between the finger and thumb. Cordate, heart-shaped. Cordiform, resembling the form of a heart. Coriaceous, of a leather-like consistence. Corneous, of a horn colour, resembling a horn. Coronal, relating to the crown or top. Coronated, crowned, or girt towards the apex. Costated, ribbed, having large ribs. Corpus, the body of the shell, the last or great wreath in which the aperture is situated. Cortex, the anterior skin or epidermis. Crenulated, notched at the margin, scalloped. Crispated, rough with waving lines. Cuneiform, shaped like a wedge. Cylindrical, round like a cylinder or a roller.