[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Appendiculata {Lankester}
         Branch Gnathopoda Straus-Durkheim, 1829
           Grade Condylopoda
             Class Arachnida Lamarck, 1801
               Branch Tracheopulmonata
                 Order Scorpionidea
                   1 Genus Scorpio Linnaeus, 1758
                   2 Genus Chelifer Geoffroy, 1762