Phylum Mollusca Linnaeus, 1758 - molluscs
   Class Bivalvia Linnaeus, 1758 - bivalves
     Subclass Heterodonta Neumayr, 1884 see Clade Heterodonta Neumayr, 1884
       Order Chamida see Order Venerida Gray, 1854
         Superfamily Cardioidea Lamarck, 1809
           Family Cardiidae Lamarck, 1809 - cockles
             Subfamily Cardiinae Lamarck, 1809
               Genus Cardium Linnaeus, 1758
                 1 Subgenus Cardium Linnaeus, 1758
                 2 Subgenus Bucardium Gray, 1853
                 3 Subgenus Orthocardium Tremlett, 1950