Ostrea latimarginata (FOSSIL) E.W. Vredenburg, 1908 †
Conradostrea lawrencei (FOSSIL) Ward & B.W. Blackwelder,1987 †
Gigantostrea leeana (FOSSIL) Wilson, 1987 †
Ostrea leveretti (FOSSIL) L.W. Stephenson, 1952 †
Peilinia levicostata (FOSSIL) B.S. Kues, 1997 †
Ostrea libella N.E. Weisbord, 1964
Ostrea lincolnensis (FOSSIL) C.S. Weaver, 1916 †
Crassostrea lineata (P.F. Röding, 1798)
Ostrea lingua (FOSSIL) Sowerby, 1840 †
Cubitostrea lisbonensis (FOSSIL) G.F. Harris, 1919 †
Ostrea lixula N.E. Weisbord, 1964
Lopha longifolium (FOSSIL) Martin, 1922 †
Ostrea ludensis (FOSSIL) G.P. Deshayes, 1861 †
Alectryonia ludoviciana (FOSSIL) G.F. Harris, 1919 †
Ostrea lusitanica (FOSSIL) Bell, 1893 †
Ostrea maculosa Forskål, 1775
Crassostrea makarovi (FOSSIL) L. Krishtofovich, 1964 †
Saccostrea malabonensis (L.A. Faustino, 1932)
Crassostrea mangle Amaral & L.R.L. Simone,2014
Ostrea manubriata (FOSSIL) R. Tate, 1887 †
Ostrea marcignyana (FOSSIL) Martin, 1860 †
Striostrea margaritacea (J.B.P.A. Lamarck, 1819)
Ostrea marginidentata (FOSSIL) Wood, 1861 †
Lopha marshii (FOSSIL) (Sowerby, 1914 †)
Ostrea marshiiformis (FOSSIL) Münster, 1841 †
Ostrea mauricensis (FOSSIL) W.M. Gabb, 1860 †
Ostrea mcnairyensis (FOSSIL) B. Wade, 1926 †
Undulostrea megadon (FOSSIL) (Hanley 1845) †
Undulostrea megodon (S.C.T. Hanley, 1846)
Margostrea merceyi (FOSSIL) (Coquand 1869) †
Ostrea mesenterica (FOSSIL) Morton, 1834 †
Ostrea messor (FOSSIL) C.J. Maury, 1925 †
Cubitostrea mezquitalensis (FOSSIL) R.L. Squires & Demetrion,1990 †
Ostrea minbuensis (FOSSIL) Cotter, 1923 †
Ostrea minerensis (FOSSIL) H.D. Russell & Landes,1937 †