scales

scales (noun, plural; Old French escale, husk): 1. A small, more or less flattened, plate-like exterior covering.

2. (Arthropoda) a. In Chelicerata, flattened, modified setae of Arachnida. b. In Crustacea, small calcareous plate on the peduncle of lepadomorph barnacles

See also: scaphocerite. c. In Insecta, flat unicellular outgrowths of the body-wall; highly modified clothing hairs of all Lepidoptera, many Collembola, in some Thysanura, Coleoptera, Diptera and Hymenoptera. 3. (Mollusca) a. In Bivalvia, localized projections of the outer shell; usually on a rib. b. In Polyplacophora, small calcareous bodies decorating the dorsal side of the girdle, sometimes closely set, overlapping and of various shapes, being smooth or with minute striations. 4. (NEMATA: Sacernentea) Thickened, retrorse modifications of the body annuli.