Gills openings extend upward above the level of pectoral fins. Anterior
dorsal fins originating at rear of or behind head; caudal fin externally
symmetrical. No V-shaped ridge on top of skull. Scales in most species
overlapping and rounded, not set at right angles to each other. Swimbladder
not connected to rear of skull. A single hypural bone attached to
last vertebra. Spine on top of first vertebra is tightly connected
to a narrow crest at the rear of the skull.