Chordata Bateson, 1885 - chordates Class Elasmobranchii Bonaparte, 1838 see Subclass Elasmobranchii Bonaparte, 1838 Subclass Selachii see Subdivision Selachii Order †Acanthodei Gunnell, 1933 see Class Acanthodii Owen, 1846 33 Family †Acanthoëssidae see Family Acanthodidae Huxley, 1861 34 Family †Ischnacanthidae Woodward, 1891 35 Family †Diplacanthidae Woodward, 1891