Protocardia purbeckense (FOSSIL) (De Loriol, 1865 †) UK, Dorset
Cardium pygmaeum (FOSSIL) W.v. Hisinger, 1837 † Estonia, Lääne-Viru
Didacna pyramidata (O.A. Grimm, 1877) Caspian Sea
Protocardia qinghaiensis (FOSSIL) Wen, 1979 † China, Germu County
Patagonicardium quadalensis (FOSSIL) D. Frassinetti& Covacevich, 1999 † Chile, Puerto Guadal
Dallocardia quadragenarium (T.A. Conrad, 1837) California, San Pedro56,9 mm
Cardium quilonense (FOSSIL) A. Dey, 1961 † India, Kerala, Kollam
Nemocardium quinarium (FOSSIL) J. Marwick, 1944 † New Zealand, South Island18 mm
Granocardium quinquecostatum (FOSSIL) J.H.F. Douvillé, 1916 † Egypt, Shamal Sina', Al-'Arish 4
Goniocardium rachitis (FOSSIL) (G.P. Deshayes, 1829 †) France, Paris Basin39 mm
Keenocardium raricostatum (FOSSIL) A.I. Kafanov, 1994 † Russia, Sakhalin
Cardium rarisquamatum (FOSSIL) A.E.M. Cossmann& Pisarro, 1904 † France, Brittany7 mm
Protocardia razavii (FOSSIL) Repin, 2013 † Iran, Razavi Khorasan, Ferdows
Agnocardia rectispina (FOSSIL) (A. von Koenen, 1893 †)
Ciliatocardium reedi (FOSSIL) (Loel & Corey, 1932 †) Russia, Kamchatka, Olyutorskiy
Protocardia regulare (FOSSIL) (Coquand, 1862 †) Egypt, Sinai Peninsula
Hypanis regularis Y.I. Starobogatov, 2004
Bucardium restinense (FOSSIL) A.A. Olsson, 1928 † Peru, Mancora
Lunulicardia retusa (C. Linnaeus, 1767) Australia, Port Hedland40 mm
Lunulicardia retusa auricula (C. Niebuhr, 1775) Egypt, Sinai Peninsula36,1 mm
Lunulicardia retusa subretusa (G.B. II Sowerby, 1841) Singapore20 mm
Fragum retusum (FOSSIL) (C. Linnaeus, 1767 †)
Protocardia rhaetica (FOSSIL) M.S. Merian, 1853 † UK, Wales, Cardiff
Vasticardium rhegminum (P.G. Oliver& H.C.G. Chesney, 1997)
Trachycardium riachuelense (FOSSIL) C.J. Maury, 1936 † Brazil, Sergipe
Afrocardium richardi (Audoin, 1826) Philippines, Aliguay Island9,2 mm
Bucardium ringens (J.G. Bruguière, 1789) Senegal, Dakar33 mm
Cardium riogramamense (FOSSIL) C.J. Maury, 1930 † Brazil, Paraíba, Conde
Ctenocardia robillardi (G.B. III Sowerby, 1894) Mauritius
Loxocardium robustum (FOSSIL) A.E.M. Cossmann, 1886 †
Dinocardium robustum (J. Lightfoot, 1786) Florida105 mm
Parvicardium roseum (FOSSIL) (J.B.P.A. Lamarck,1819 †) Italy, Emilia
Trachycardium rossi (FOSSIL) J. Marwick, 1944 †
Vasticardium rubicundum (L.A. Reeve, 1844) Tanzania36 mm
Vepricardium rubrohamatum R.P.A. Voskuil& W.J.H. Onverwagt, 1988 Philippines, Bohol44,2 mm