One of the subclasses of fishes. They have an arterial cone and bulb, spiral intestinal valve, and the optic nerves united by a chiasma. Many of the species are covered with bony plates, or with ganoid scales; others have cycloid scales. [1913 Webster
" They were numerous, and some of them of large size, in early geological periods; but they are represented by comparatively few living species, most of which inhabit fresh waters, as the bowfin, gar pike, bichir, Ceratodus, paddle fish, and sturgeon."