Mactromeris abbotti (FOSSIL) Wiedley, 1928 †
Mactra abbreviata J.B.P.A. Lamarck, 1818
Mactra abbreviata meritriciformis L.A. Reeve, 1854
Mactra abbreviata obesa L.A. Reeve, 1854
Mactra achatina H.S. Holten, 1802
Mactra achatina maculosa J.B.P.A. Lamarck, 1818
Mactra achatina ornata J.E. Gray, 1837
Zenatia acinaces (J.R.C. Quoy& J.P. Gaimard, 1835)
Zenatia acinaces cumingiana G.P. Deshayes, 1854
Maorimactra acuminella (FOSSIL) Finlay, 1930 †
Andrusella acutecarinata (FOSSIL) (Andrussov 1902) †
Mactromeris acutirostrata (FOSSIL) A. Packard, 1916 †
Scissodesma acutissima (R. von Cosel, 1995)
Spisula adamsi A.A. Olsson, 1961
Mactromeris addicotti (FOSSIL) S. Kanno, 1971 †
Crassula aequilatera (L.A. Reeve, 1854)
Mactra aequisulcata G.B. III Sowerby, 1894
Mactrellona alata (L. Spengler, 1802)
Mactromeris albaria (FOSSIL) (T.A. Conrad, 1848 †)
Spisula albertantonorum (FOSSIL) R. Marquet, 2005 †
Lutraria alderi Unknown
Tresus allomyax E.V. Coan& P.H. Valentich-Scott, 2000
Mactra alta G.P. Deshayes, 1855
Cyclomactra altilunula (FOSSIL) (J. Marwick, 1927 †)
Anatina anatina (L. Spengler, 1802)
Scissodesma angolensis (R. von Cosel, 1995)
Mactrotoma angulifera (L.A. Reeve, 1854)
Lutraria angusta (FOSSIL) G.P. Deshayes, 1830 †
Mactrotoma angusta (L.A. Reeve, 1854)
Zenatiopsis angustata (FOSSIL) R. Tate, 1879 †
Lutraria angustior R.A. Philippi, 1844
Mactrotoma antecedens (T. Iredale, 1930)
Mactra antiquata L. Spengler, 1802
Mactra aphrodina L.A. Reeve, 1854
Spisula arcuata (FOSSIL) (Sowerby, 1817 †)