cosmoid scale
scale with four layers, an outer, thin, porous layer of vitrodentine (sometimes denticulate or lacking denticles, adenticulate), a middle layer of dentine with pulp cavities or canals (cosmine), a spongy deeper layer of loose spongy bone containing osteoblasts, and lastly a laminar layer of isopedine with osteocytes and Sharpney\'s fibres. Grows by adding to inner layer only, e.g. Crossopterygii, Placodermi; not found in extant fishes

Dictionary of ichthyology. 2009.

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  • Fish — /fish/, n. Hamilton, 1808 93, U.S. statesman: secretary of state 1869 77. * * * I Any of more than 24,000 species of cold blooded vertebrates found worldwide in fresh and salt water. Living species range from the primitive lampreys and hagfishes… …   Universalium

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