Author: Gill, 1864
Diagnostic Features:
Anterior nasal flaps very short, not expanded into barbels; snout short, bulbously conical, length less than 2/5 of head length and much less than distance from mouth to pectoral origins; gill openings small, uniformly broad; lips expanded, fleshy, suctorial, allowing the shark to attach to its prey like a lamprey; teeth strongly different in upper and lower jaws, uppers small, with narrow, acute, erect cusps and no cusplets, not bladelike, lowers very large, bladelike, interlocked, with a high broad, erect cusp but no blade, edges not serrated; tooth rows 29-37/19-31. Both dorsal fins spineless; first dorsal fin far posterior, origin far behind pectoral fins and somewhat anterior to pelvic origins, insertion over pelvic bases; second dorsal fin slightly larger than first but with base about equal to first dorsal base; origin of second dorsal about over pelvic rear tips; pectoral fins with short, narrowly to broadly rounded free rear tips and inner margins, not expanded and acute or lobate; caudal fin varying from asymmetrical to nearly symmetrical, paddle-shaped or not, with a short upper lobe, short to long lower lobe, and a strong subterminal notch. No precaudal pits but with low lateral keels on caudal peduncle, no midventral keel. Dermal denticles flat and blocklike, not pedicellate, no posterior cusps on flat, depressed crowns. Cloaca normal, not expanded as a luminous gland. Colour medium grey or grey-brown with light-edged fins.
Remarks:
The arrangement of this genus follows Garrick and Springer (1964).