n. plCycloidei(Zoöl) An order of fishes, formerly proposed by Agassiz, for those with thin, smooth scales, destitute of marginal spines, as the herring and salmon. The group is now regarded as artificial.
Century Dictionary and Cyclopedia
cycloideiIn L. Agassiz's system of classification, the fourth order of fishes, including those with cycloid scales—that is, scales of the usual type, marked with concentric rings and not enameled or pectinated. It was contrasted with the orders Ctenoidei, Ganoidei, and Placoidei. It has proved to be an artificial assemblage of forms, embracing most of the malacopterygian fishes of Cuvier, but also many of his acanthopterygians, and is not now in use.