Lopha pulligera (FOSSIL) G.A. Goldfuss, 1834 †
Ostrea puruensis (FOSSIL) Martin, 1914 †
Peilinia quadriplicata (FOSSIL) (Shumard, 1854 †)
Ostrea radiata A. Valenciennes
Crassostrea raincourti (FOSSIL) (G.P. Deshayes, 1858 †)
Ostrea raveneliana (FOSSIL) M. Tuomey & Holmes,1855 †
Ostrea resupinata (FOSSIL) G.P. Deshayes, 1858 †
Ostrea retusa Sowerby, 1871
Crassostrea rhizophorae (L. Guilding, 1828)
Ostrea riograndensis (FOSSIL) Stanton, 1947 †
Crassostrea rivularis (A.A. Gould, 1861)
Ostrea roncana (FOSSIL) P. Partsch, 1870 †
Dendostrea rosacea (G.P. Deshayes, 1836)
Ostrea rouaulti (FOSSIL) A.E.M. Cossmann, 1923 †
Curvostrea rouvillei (FOSSIL) (Conquand 1862) †
Curvostrea rouvillei (FOSSIL) (Coquand, 1862. †)
Cubitostrea rugifera (FOSSIL) W.H. Dall, 1898 †
Ostrea rugosa (FOSSIL) Smith, 1817 †
Ostrea russelli (FOSSIL) H.D. Russell & Landes,1937 †
Crassostrea rutiformis (FOSSIL) Bohm, 1926 †
Ostrea sacyi (FOSSIL) A.E.M. Cossmann& M.A. Peyrot, 1914 †
Ostrea sallomacensis (FOSSIL) A.E.M. Cossmann& M.A. Peyrot, 1914 †
Ostrea samanensis (FOSSIL) A.A. Olsson, 1928 †
Ostrea sandalina (FOSSIL) G.A. Goldfuss, 1834 †
Dendostrea sandvichensis (G.B. II Sowerbyin L.A. Reeve, 1871)
Agerostrea sannonis (FOSSIL) (White) †
Ostrea sansebastiana (FOSSIL) C.J. Maury, 1920 †
Ostrea saxitoniana (FOSSIL) McLearn, 1929 †
Conradostrea sculpturata (FOSSIL) (T.A. Conrad, 1840 †)
Saccostrea scyphophilla (F. Péron & C.A. Lesueur,1807)
Cubitostrea sellaeformis (FOSSIL) (T.A. Conrad, 1832 †)
Ostrea semiplana (FOSSIL) Sowerby, 1825 †
Dendostrea senegalensis (J.F. Gmelin, 1791)
Ostrea seymourensis (FOSSIL) Zinsmeister, 1984 †
Crassostrea sikamea (Amemiya, 1928)