Kingdom [Animalia] Linnaeus, 1758 - animals
   Phylum Chordata Bateson, 1885 - chordates
     Subphylum Vertebrata Cuvier, 1812 - vertebrates
       Class Agnatha Cope, 1889
         1 "Ostracoderms"
         2 Order Petromyzontia
         3 Order Myxinoidea - hagfishes