Protocardia purbeckense (FOSSIL) (De Loriol, 1865 †)
Cardium pygmaeum (FOSSIL) W.v. Hisinger, 1837 †
Didacna pyramidata (O.A. Grimm, 1877)
Protocardia qinghaiensis (FOSSIL) Wen, 1979 †
Patagonicardium quadalensis (FOSSIL) D. Frassinetti& Covacevich, 1999 †
Dallocardia quadragenarium (T.A. Conrad, 1837)
Cardium quilonense (FOSSIL) A. Dey, 1961 †
Nemocardium quinarium (FOSSIL) J. Marwick, 1944 †
Granocardium quinquecostatum (FOSSIL) J.H.F. Douvillé, 1916 †
Goniocardium rachitis (FOSSIL) (G.P. Deshayes, 1829 †)
Keenocardium raricostatum (FOSSIL) A.I. Kafanov, 1994 †
Cardium rarisquamatum (FOSSIL) A.E.M. Cossmann & Pisarro,1904 †
Protocardia razavii (FOSSIL) Repin, 2013 †
Agnocardia rectispina (FOSSIL) (A. von Koenen, 1893 †)
Ciliatocardium reedi (FOSSIL) (Loel & Corey, 1932 †)
Protocardia regulare (FOSSIL) (Coquand, 1862 †)
Hypanis regularis Y.I. Starobogatov, 2004
Bucardium restinense (FOSSIL) A.A. Olsson, 1928 †
Lunulicardia retusa (C. Linnaeus, 1767)
Lunulicardia retusa auricula (C. Niebuhr, 1775)
Lunulicardia retusa subretusa (G.B. II Sowerby, 1841)
Fragum retusum (FOSSIL) (C. Linnaeus, 1767 †)
Protocardia rhaetica (FOSSIL) M.S. Merian, 1853 †
Vasticardium rhegminum (P.G. Oliver& H.C.G. Chesney, 1997)
Trachycardium riachuelense (FOSSIL) C.J. Maury, 1936 †
Afrocardium richardi (Audoin, 1826)
Bucardium ringens (J.G. Bruguière, 1789)
Cardium riogramamense (FOSSIL) C.J. Maury, 1930 †
Ctenocardia robillardi (G.B. III Sowerby, 1894)
Loxocardium robustum (FOSSIL) A.E.M. Cossmann, 1886 †
Dinocardium robustum (J. Lightfoot, 1786)
Parvicardium roseum (FOSSIL) (J.B.P.A. Lamarck,1819 †)
Trachycardium rossi (FOSSIL) J. Marwick, 1944 †
Vasticardium rubicundum (L.A. Reeve, 1844)
Vepricardium rubrohamatum R.P.A. Voskuil& W.J.H. Onverwagt, 1988