Nemocardium khomenkoi (FOSSIL) A.I. Kafanov& K. Ogasawara, 1999 †
Cardium khowaiteri (FOSSIL) Abbass, 1972 †
Trachycardium kinsmarae (FOSSIL) J. Makiyama, 1934 †
Frigidocardium kiranum K. Sakurai & T. Habe,1966
Ciliatocardium kirkerensis (FOSSIL) (Clark, 1918 †)
Laevicardium kirkinskayae (FOSSIL) Krishtofovich, 1957 †
Fragum kishimaense (FOSSIL) (Nagao) †
Keenocardium kljutschiense (FOSSIL) (Krishtofovich, 1969 †)
Monodacna knipowitschi (B.M. Logvinenko& Y.I. Starobogatov, 1966)
Parvicardium kochi (FOSSIL) (C.G. Semper, 1861 †)
Protocardia koshikijimensis (FOSSIL) K. Amano, 1958 †
Laevicardium kovacovense (FOSSIL) Senes, 1958 †
Nemocardium kovatschensis (FOSSIL) L. Krishtofovich, 1947 †
Vasticardium kuboderai N.N. Thach, 2015
Keenocardium kuluvense (FOSSIL) A.I. Kafanov, 1984 †
Laevicardium kuluvense (FOSSIL) V.N. Sinelnikova, 1980 †
Granocardium kummeli (FOSSIL) (Weller, 1907 †)
Cardium kunstleri (FOSSIL) A.E.M. Cossmann& M.A. Peyrot, 1911 †
Fulvia kurodai (FOSSIL) K.M. Hatai & S. Nisiyama,1958 †
Trachycardium lacunosum (FOSSIL) (L.A. Reeve, 1845 †)
Fulvia laevigata (C. Linnaeus, 1758)
Fulvia laevigata papyracea (J.G. Bruguière, 1789)
Adacna laeviuscula (K.E.I. von Eichwald,1829)
Serripes laperousii (G.P. Deshayes, 1839)
Chesacardium laqueatum (FOSSIL) (T.A. Conrad, 1830 †)
Papyridea lata (I. von Born, 1778)
Nemocardium lene (FOSSIL) (T.A. Conrad, 1856 †)
Cardium lennieri (FOSSIL) A.E.M. Cossmann & G. Pissarro †,
Cardium leognanense (FOSSIL) C. Mayer, 1866 †
Phlogocardia leonense (FOSSIL) W.C. Mansfield, 1932 †
Chesacardium leptopleura (FOSSIL) (T.A. Conrad, 1841 †)
Laevicardium leptorinum (FOSSIL) D.T. Dockery, 1982 †
Parvicardium levesquei (FOSSIL) (Orbigny, 1850 †)
Dinocardium levyi (FOSSIL) H.G. Richards, 1953 †
Americardia lightbourni Y.C. Lee & M. Huber, 2012