Semionotiformes

(vertebrate zoology) An order of actinopterygian fishes represented by the single living genus Lepisosteus, the gars; the body is characteristically encased in a heavy armor of interlocking ganoid scales.

An order of actinopterygian fishes which appeared first in the upper Permian, reached maximum development in the Triassic and Jurassic, and persists in the Recent fauna as the gars.

In the Semionotiformes the body is encased in a heavy armor of interlocking ganoid scales, which are thick, are more or less rhomboidal, and have an enameilike surface. Modern forms have an elongate body and bony jaws provided with enlarged conical teeth (see illustration).

Spotted gar (Lepisosteus oculatus). (After G. B. Goode, Fishery Industries of the United States, 1884)

The single Recent family, Lepisosteidae, contains one genus, Lepisosteus, with seven species restricted to lowland fresh and brackish waters of North and Central America. See also Actinopterygii.