Author: Linnaeus, 1758
Field Marks:
Short to rather long snout, short anterior nasal flaps, low, bladelike cutting teeth in both jaws, no anal fin, stout, ungrooved fin spines on both dorsal fins, caudal peduncle with lateral keels and usually a precaudal pit, caudal fin without a subterminal notch.
Diagnostic Features:
Anterior nasal flaps short, not elongated as barbels; snout flattened, short to very long, and broadly rounded to pointed, length 2/5 to 3/5 of head length and 3/5 to 1 1/5 times distance from mouth to pectoral origins; gill openings moderately broad and about equally wide; lips thin, not pleated or suctorial; teeth similar in both jaws, bladelike, interlocked, with a single oblique cusp and distal blade on a low crown and root, upper teeth slightly smaller than lowers, edges smooth in living species (serrated in some fossils); tooth rows 24 to 29/20 to 26. Both dorsal fins with long, stout, ungrooved spines; first dorsal origin varying from over pectoral bases to slightly posterior to pectoral free rear tips, insertion well anterior to pelvic origins but varying from somewhat closer to the pectoral bases than the pelvics to vice versa; second dorsal fin usually somewhat smaller than first dorsal but up to first dorsal size in one species, base subequal to about 3/4 of first dorsal base; pectoral fins with short to moderately long, narrowly rounded to acutely angular rear tips and inner margins, not greatly elongated or broadly lobated; caudal fin asymmetrical, not paddle-shaped, with a long upper lobe and lower lobe varying from moderately long to very short, subterminal notch absent. Lateral keels and usually precaudal pits present on caudal peduncle, but no midventral keels. Dermal denticles with low, pedicellate, lanceolate or tricusped and triridged, flat, leaf-shaped crowns. Cloaca without a luminous gland. Colour usually grey or grey-brown above, lighter below, fins in some species with conspicuous white or black markings.
Remarks:
The arrangement of the genus follows Bigelow and Schroeder (1957), Bass, d'Aubrey and Kistnasamy (1976), and Chen, Taniuchi and Nose (1979).