Author: Compagno, 1973
Field Marks:
6 or 7 pairs of gill slits, one dorsal fin, anal fin.
Diagnostic Features:
Trunk cylindrical or somewhat compressed, not flattened and raylike. Head conical to slightly depressed, not expanded laterally; 6 or 7 pairs of gill slits present on sides of head, with the posteriormost in front of pectoral fin origins; spiracles present and very small, well behind and above level of eyes; nostrils without barbels, nasoral grooves or circumnarial grooves, separate from mouth, anterior nasal flaps short and not reaching mouth; eyes on sides of head, without nictitating lower eyelids; snout very short to moderately long, truncated to conical, not greatly elongated or flattened, and without lateral teeth or rostral barbels; mouth large, arched and elongated, extending well behind eyes; labial furrows reduced or absent, on lower jaw when present; teeth weakly to strongly differentiated along the jaws, without enlarged anterior or posterior teeth and without a gap or small intermediate teeth between anterior and lateral teeth in the upper jaw. A single spineless dorsal fin present, with origin over or behind pelvic fin insertions; pectoral fins small to moderately large, not expanded and raylike, without triangular anterior lobes that cover the gill slits; pelvic fins small to moderately large, with vent continuous with their inner margins; anal fin present; caudal fin with a long dorsal lobe and the ventral lobe short to absent; vertebral axis elevated into the dorsal caudal lobe. Intestinal valve of spiral or ring type.