Ganoids

Ganoids, an order of fishes once very large, but now decadent, being represented by only seven living genera. These are (1) predominantly cartilaginous forms—Acipenser (sturgeon), Scaphirhynchus, Spatularia (or Polyodon), and (2) bony Ganoids—Polypterus, Calamiochthys, Lepidostens (bony pike), and Amia. On the other hand, the majority of fossil fish in paleozoic times are Ganoids—e.g. Pterichthys, Coccosteus, Cephalaspis, Pteraspis, Rhizodus. The general characters are noted under FISHES.