[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Gephyræa
         Class Priapulidæ Gosse, 1855
           1 Genus Priapulus Lamarck, 1816
           2 Genus Halicryptus v. Siebold, 1849