Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Gastropoda Cuvier, 1795 - snails and slugs
     Subclass Prosobranchia Milne-Edwards, 1848 - prosobranchs see Class Gastropoda Cuvier, 1795
       Superorder Archaeogastropoda Thiele, 1925
         Order Vetigastropoda Salvini-Plawen, 1980 - archaeogastropods s.l.
           Suborder Neritopsina Cox, 1960 see Order Neritopsina Cox & Knight, 1960
             Superfamily Helicinoidea Férussac, 1822
               Family Helicinidae Férussac, 1822 - helicinids
                 Subfamily Helicininae Férussac, 1822
                   Genus Alcadia Gray, 1840
                     1 Subgenus Analcadia Wagner, 1907
                     2 Subgenus Emoda Adams & Adams, 1856
                     3 Subgenus Glyptalcadia Boss & Jacobson, 1973
                     4 Subgenus Hjalmarsona Baker, 1954
                     5 Subgenus Idesa Adams & Adams, 1856
                     6 Subgenus Penisoltia Baker, 1954
                     7 Subgenus Striatemoda Baker, 1940