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Show 1867.] DR. J. E. GRAY ON THE CALYPTRcEIDiE. 735 The shells are rarely flat when the animal has affixed itself over a cavity in stones or shells. TROCHITA RADIANS. Trochus radians, Desh. Var. Dark chestnut (Chenu, Man. f. 2343). T. spirata, Forbes. Shell solid ; whorls flat, with oblique ribs ; margins of base dentated. Var. Shell distorted, nearly flat; whorls indistinctly marked. Hab. Coast of Peru ; Valparaiso ; Straits of Magellan. 2. CLYPEOLA. Shell conical, circular, spiral, thin. Apex central. Whorls several, well developed. Base concave, circular. Mouth large, oblong, four-sided. Axis central, imperforated, spiral, exposed to the apex of the cavity. Periostraca horny, thin, lamellar. A Trochila with somewhat the appearance of a Mitrella. * Skull depressed, smooth. 1. CLYPEOLA MAGELLANICA. Trochita clypeolum, Reeve. Shell thin, conical, depressed, smooth, covered with laminar foliaceous periostraca; base nearly flat. Hab. Magellan Straits. 2. CLYPEOLA TENUIS, n. s. Shell thin, conical, depressed, smooth. Hab. New Zealand. ** Shell high, conical; whorls costate. 3. CLYPEOLA CORRUGATA. Trochita corrugata, Reeve. "T. spirata, var.," Reeve; Chenu, Man. f. 2347, 2348. Calyptreea pileus, Lamk.; Deless. Icon. t. 34. f. 2. Shell high, conical, acute; whorls flat, obliquely costate, or nearly smooth ; base deeply concave. Hab. Peru. Var. Icevis. Shell smooth and thin ; the spire of the column of one specimen more exposed and open. Hab. Falkland Islands. 3. TROCHELLA. Shell obliquely conical, depressed. Apex subcentral. Whorls well developed, covered with a horny lamellar periostraca. Nucleus |