Phthonia regularis (FOSSIL) Barrande, 1881 †
Botulopsis reisi (FOSSIL) Waller 2005 †
Exosiperna relata T. Iredale, 1929
Modiolus restorationensis (FOSSIL) Van Winkle, 1918 †
Promytilus retusus (FOSSIL) Chronic, 1952 †
Jolya rhomboidea (L.A. Reeve, 1857)
Jolya rhomboidea sirahensis (F.P. Jousseaume, 1891)
Rhomboidella rhyllensis (J.H. Gatliff& C.J. Gabriel, 1912)
Brachidontes rigaulti (FOSSIL) G.P. Deshayes, 1858 †
Mytilus rimosus (FOSSIL) J.B.P.A. Lamarck, 1805 †
Lithophaga ripleyana (FOSSIL) W.M. Gabb, 1862 †
Lithophaga robusta F.P. Jousseaume in É. Lamy,1919
Rhomboidella rodriguesensis P.G. Oliver & A.M. Holmes,2004
Brachidontes rodriguezii (A.V.M.D. D'Orbigny,1842)
Brachidontes rostratus (R.W. Dunker, 1857)
Dacrydium rostriferum F.R. Bernard, 1978
Septifer rudis W.H. Dall, P. Bartsch& H.A. Rehder, 1938
Septifer rufolineatus (E.A. Smith, 1911)
Lithophaga rugosa (FOSSIL) (Orbigny, 1845 †)
Modiolus rumphii (R.A. Philippi, 1847)
Septifer saccoi (FOSSIL) A.E.M. Cossmann & M.A. Peyrot †,
Modiolus sacculifer (S.S. Berry, 1953)
Mytilus sachalinensis (FOSSIL) Simonova, 1941 †
Amygdalum sagittatum (H.A. Rehder, 1935)
Mytilus salevensis (FOSSIL) De Loriol †
Lioberus salvadoricus (L.G. Hertlein& A.M. Strong, 1946)
Modiolus salzstettensis (FOSSIL) Hohenstein, 1913 †
Xenostrobus sambasensis (P. Dautzenberg, 1903)
Septifer samiri (FOSSIL) Abbass, 1962 †
Modiolus sandbergeri (FOSSIL) M. Glibert & de Heinzelin,1954 †
Dacrydium sandersi J.A. Allen, 1998
Modiolus sanharica (FOSSIL) C.J. Maury, 1936 †
Bathymodiolus satsopensis (FOSSIL) S. Kiel & K. Amano,2013 †
Modiolus scalprum (FOSSIL) J. de C. Sowerby, 1821 †
Exosiperna scapha (J.C. Verco, 1908)