Chordata Bateson, 1885 - chordates Class Elasmobranchii Bonaparte, 1838 see Subclass Elasmobranchii Bonaparte, 1838 Subclass Selachii see Subdivision Selachii Order Selachophidichthyoidei [monotypic] see Order Hexanchiformes Compagno, 1973 49 Family Chlamydoselachidae Garman, 1884 [monotypic] - frill sharks