Table of Contents
These are rather small sharks, with two dorsal fins without spines, the second dorsal (in Atlantic species) nearly as large as the first, and they have an anal fin. The tail fin is very strongly asymmetrical, its lower anterior corner forming a low but rather definite lobe in some, but not in others. The teeth are small, with several rows in function simultaneously, flat, and pavement-like in some, but with three or four definite cusps in others. The eye has no nictitating ("winking") membrane, but only a longitudinal fold along the lower eyelid. They resemble the requiem sharks (Family Carcharhinidae, p. 36), except for the teeth, and for the lack of a nictitating membrane. Only one species is known from the Gulf of Maine, or is ever likely to be found there.