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Show 740 DR. J. E. GRAY ON THE CALYPTRLEID/E. [June 27, cavity in the shelly plate of Mitrella; but the plate is attached each of its side edges. The more convex species might be confounded with Crepipatella; but they are always known by the fold forming a subcentral ridge on the lower surface of the plate, and ending in the small shallow pit like the scar of a muscle. This group has been regarded as a subgenus of Crypta; but it is more allied to Mitrella. 1. ERGCEA, Adams ; Chenu. Shell nearly flat; apex posterior, marginal; nucleus spiral; whorls rapidly enlarging. The shells when they live in cavities are concave externally,-and when living on a rough surface, corrugated like other Calyptrceidce. ERGCEA WALSHI. Crepidula walshi, Hermannsen. (C. plana, Chenu, Man. f. 2364. Var. distorted and rugose, G. plana, Adams & Reeve.) Hab. Ceylon; Bombay. 2. NOICIA. Shell subcircular or oblong, convex, spiral; whorls one and a half or two; the apex subcentral, subposterior; nucleus spiral; cavity concave, deeper under the apex; internal plates concave, thin, with the fold forming a narrow linear cavity open to the apex of the shell. NOICIA CHINENSIS, n. s. (in Cuming's Collection). Shell pale brown, smooth, or slightly concentrically striated. Hab. China. Var. Shell very thin, convex ; the internal plate thin, with the fold only slightly marked and solid. Tribe IV. Shell conical, spiral; spire of few rapidly enlarging whorls ; cavity conical, with a well-developed oblique subspiral lamina on one side, from the tip, which has the inner or pillar-edge reflexed, forming a pit or solid rib. Mitrellina. 1. MITRELLA. Shell conical, like Poculina ; but the internal plate is oblique and subspiral; the reflexed part of the pillar-lip is closely applied to the plate, and only forming a thickened edge to the plate, there being a small impression like the scar of a muscle at the lower part of it. 1. MITRELLA CHINENSIS. Shell white or rosy; outer surface with minute tubular spines or tubercles. Patella chinensis, Montagu. Calyptrcea chinensis, Lamk., &c. Hab. Coasts of Europe. |