Vertebrata Cuvier, 1812 - vertebrates Gnathostomata Class Chondrichthyes Huxley, 1880 - cartilaginous fishes Subclass Elasmobranchii Bonaparte, 1838 - shark-like fishes Superorder Euselachii Hay, 1902 see Infraclass Euselachii Hay, 1902 Order Galeomorpha see Superorder Galeomorphii Compagno, 1973 Suborder Hexanchoidea see Order Hexanchiformes Compagno, 1973 1 Family Hexanchidae Gray, 1851 - cow sharks 2 Family Chlamydoselachidae Garman, 1884 - frill sharks