Mactra kanakina S.M. Souverbie, 1860
Mactra kavakamiensis (FOSSIL) Krishtofovich, 1954 †
Tresus keenae (J.T. Kuroda & T. Habe,1950)
Mactra kunstleri (FOSSIL) A.E.M. Cossmann& M.A. Peyrot, 1909 †
Austromactra lamberti (FOSSIL) (G.P. Deshayes, 1857 †)
Resania lanceolata J.E. Gray, 1853
Pteropsella lapidosa (FOSSIL) (T.A. Conrad, 1846 †)
Mactra largillierti R.A. Philippi, 1849
Mulinia lateralis (T. Say, 1822)
Lutraria latissima (FOSSIL) G.P. Deshayes, 1830 †
Austromactra laudunensis (FOSSIL) (A. Watelet, 1853 †)
Oxyperas leda (FOSSIL) (Finlay, 1924 †)
Oxyperas lentiginosa (A.A. Gould, 1852)
Mulinia levicardo (E.A. Smith, 1881)
Mactra lilacea J.B.P.A. Lamarck, 1818
Austromactra loustauae (FOSSIL) (J.F. Bayan, 1873 †)
Lutraria lutraria (C. Linnaeus, 1767)
Mactra luzonica L.A. Reeve, 1854
Cryptodon mactraeformis (FOSSIL) R. Tate, 1887 †
Mactra maculata J.F. Gmelin, 1791
Mactra malina C. Hedley, 1915
Mactra maracaibensis (FOSSIL) F. Hodson, 1931 †
Mactra marplatensis M. Doello-Jurado, 1918
Mactra marwicki (FOSSIL) A.G. Beu, 2006 †
Leptomactra marylandica (FOSSIL) (W.H. Dall, 1898 †)
Petromactra mathewsonii (FOSSIL) (W.M. Gabb, 1864 †)
Nannomactra matthewsi (R. Tate, 1888)
Lutraria maxima I.H. Jonas, 1844
Pseudocardium meganosensis (FOSSIL) Clark & Woodford, 1927 †
Mactra mekranensis (FOSSIL) R.B. Newton, 1905 †
Rangia mendica (A.A. Gould, 1851)
Mactra mera L.A. Reeve, 1854
Mactromeris mercedensis (FOSSIL) A. Packard, 1916 †
Raeta meridionalis R. Tate, 1889
Mactromeris merriami (FOSSIL) A. Packard, 1916 †