Author: Compagno, 1973
Diagnostic Features:
Trunk cylindrical and not raylike. Head conical to cylindrical and not laterally expanded; 5 pairs of gill slits present on sides of head, either entirely in front of pectoral bases or with the last two above the pectoral bases; spiracles usually present and very small, well behind the eyes; nostrils without barbels, circumnarial grooves, or nasoral grooves, well separated from eyes, with anterior nasal flaps not expanded and far from mouth; eyes lateral or slightly dorsolateral on head, without nictitating lower eyelids; snout very short and bluntly rounded to long and conical or flattened, usually not bladelike and not formed as a rostral saw with lateral teeth and vertral barbels; mouth moderately large to very large, strongly arched, extending well behind eyes; labial furrows short or absent, when present on lower jaw; teeth usually well differentiated along jaws, with enlarged anterior teeth, a gap or small intermediate teeth separating the anterior teeth from the lateral teeth in the upper jaw, but with posterior teeth not enlarged. Two dorsal fins, without spines, the first with its origin over the interspace between pectoral and pelvic bases or over the pectoral bases; pectoral fins moderate-sized to large but not raylike, without triangular anterior lobes; pelvic fins small to moderately large, with vent continuous with their inner margins; anal fin present; caudal fin with a long dorsal lobe but with ventral lobe varying from long (but shorter than the dorsal lobe) to absent; vertebral axis raised into the dorsal caudal lobe. Intestinal valve of ring type.