The ganoids or Ganoidei are an order of fish. The families of this order are chiefly characterized by angular, rhomboidal, polygonal, or circular scales composed of horny or bony plates covered with a thick plate of glossy enamel-like substance.
The ganoids were most numerous in Paleozoic and early Mesozoic times, but are now represented by seven genera: Lepidosteus, the bony pikes or gar-pikes of the North American fresh-water lakes; Polypterus, represented by a single species occurring in rivers of tropical Africa; Calamoichthys, a similar genus found in Old Calabar; Amia, the fresh-water mud-fish of North America; Acipenser, represented by the sturgeon; Scaphirhynchius, best known by the so-called shovel-nosed sturgeon of the Mississippi basin; and the genus Polyodon or Spatularia, the paddle-fishes of the Mississippi and great rivers of China. Research Ganoid
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