Author: Gill, 1893
Diagnostic Features:
Head without laterally expanded blades; eyes elongated and slitlike, their lengths over 2 times the height; nictitating eyelids rudimentary; spiracles present and very large; anterior nasal flaps broadly angular, not barbel-like; internarial width about 2.8 times the nostril width; labial furrows very short; teeth small, with acute narrow cusps, lateral cusplets, and strong basal ledges and grooves, not bladelike and similar in both jaws; posterior teeth comblike; tooth rows very numerous, 202 to 294/258 to 335. Precaudal pits absent. First dorsal fin very large, low and formed as a rounded keel, about as long as caudal fin; first dorsal base on back with insertion just opposite pelvic origins and origin about opposite free rear tips of pectorals; midpoint of first dorsal base well in front of pelvic origins; pectoral fins with radials confined to bases of fins; ventral caudal lobe absent or very weak; no undulations or ripples in dorsal caudal margin. Neurocranium with supraorbital crests; vertebral centra without strong, wedge-shaped intermedial calcifications. Valvular intestine with a spiral valve of 17 turns. Colour plain except for darker fins. Development ovoviviparous.
Remarks:
Most writers recognize this family for the false catsharks, Pseudotriakis. See Compagno (1979) for a discussion of the rationalle for recognizing the family and its relationships to other carcharhinoids. The odd New Zealand proscylliid Gollum is thought to be the closest living relative of Pseudotriakis, and there is some merit in an alternate scheme of including Gollum and Pseudotriakis in a common taxon (Compagno, 1979).