Author: Compagno, 1973
Diagnostic Features:
Trunk cylindrical to strongly depressed and somewhat raylike; head conical and slightly elevated to strongly depressed, not laterally expanded; 5 pairs of gill slits present on sides or on dorsolateral surface of head, the last two or more over the pectoral bases; spiracles present and small to very large, behind and below or at level of eyes; nostrils with barbels on the lateral surfaces of the anterior nasal flaps, strong nasoral grooves, and circumnarial grooves present or absent, connected to mouth, with anterior nasal flaps expanded posteriorly and reaching mouth; eyes lateral or dorsolateral on head, without true nictitating lower eyelids but sometimes with a subocular pocket below eyes; snout short to very short and bluntly rounded to truncated, not sawlike and without rostral barbels; mouth moderate to large, arched or virtually transverse and short, well in front of eyes; labial furrows very large, present on both jaws; teeth not strongly differentiated along jaws, without enlarged anterior or posterior teeth, and no small anterior teeth or a gap between anterior and lateral teeth in upper jaw; two dorsal fins, without spines, the first with its origin varying from over the pectoral fins to behind the pelvic fin bases but usually over or behind the pelvic bases; pectoral fins small to moderately large, not raylike and without triangular anterior lobes; pelvic fins moderately large, with vent usually continuous with their inner margins; anal fin present; caudal fin with a moderately long dorsal lobe but with ventral lobe varying from moderately long (but shorter than the dorsal lobe) to absent; vertebral axis raised into the dorsal caudal lobe; intestinal valve of spiral or ring type.