Superphylum Deuterostomia Grobben, 1908 - deuterostomes see Infrakingdom Deuterostomia Grobben, 1908
   Phylum Chordata Bateson, 1885 - chordates
     Subphylum Craniata auct.
       Superclass Myxinomorphi [monotypic] see Infraphylum Myxinomorphi
         Class Myxini Jaekel, 1911 [monotypic]
           Order Myxiniformes - hagfishes
             Family Myxinidae Rafinesque, 1815 - hagfishes
               Subfamily Eptatretinae Bonaparte, 1850 - multi-gill hagfishes
                 1 Genus Eptatretus Cloquet, 1819
                 2.1 Genus Paramyxine Dean, 1904 see Genus Eptatretus Cloquet, 1819
                 2.2 Genus Quadratus Wisner, 1999 see Genus Eptatretus Cloquet, 1819