No anal fin	Flat body, raylike, mouth in front						Angel sharks Squatiniformes
	Not raylike		Long snout, sawlike				Saw sharks Pristiophoriformes
			Short snout, not sawlike				Dogfish sharks Squaliformes

With anal fin	5 gill slits 2 dorsal fins	Dorsal fins without spines	Mouth behind eyes	Nicitating membrane			Ground sharks Carcharhiniformes
				No nicitating membrane			Mackerel sharks Lamniformes
			Mouth in front of eyes				Carpet sharks Orectolobiformes
		Dorsal fins with spines					Bullhead sharks Heterodontiformes
	6-7 gill slits						Frilled and cow sharks Hexanchiformes