[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Appendiculata {Lankester}
         Branch Rotifera
           Class Rotifera
             Order Bdelligrada
               1 Genus Hydatina Ehrenberg, 1828, nom. illeg. see Genus Epiphanes Ehrenberg, 1832
               2 Genus Rotifer Cuvier, 1798 see Genus Rotaria Scopoli, 1777