Rimula mexicana S.S. Berry, 1969
Fissurella mexicana (FOSSIL) Perrilliat, 1972 †
Emarginula meyeri (FOSSIL) Gardner †
Emarginula micans A. Adams, 1852
Cornisepta microphyma (P. Dautzenberg& H. Fischer, 1896)
Fissurella microtrema G.B. I Sowerby, 1835
Zeidora milerai J. Espinosa, J.A. Ortea& R. Fernández-Garcés, 2005
Lucapinella milleri S.S. Berry, 1959
Diodora minuta (J.B.P.A. Lamarck, 1822)
Diodora mirifica B. Métivier, 1972
Diodora mississippiensis (FOSSIL) (T.A. Conrad, 1848 †)
Hemimarginula modesta (C.B. Adams, 1872)
Monodilepas monilifera (F.W. Hutton, 1873)
Monodilepas monilifera cookiana R.K. Dell, 1953
Cornisepta monsfuji M. Chino, 2009
Emarginula montrouzieri S.M. Souverbie, 1872
Fissurella morrisoni J.H. McLean, 1970
Emarginula muensteri (FOSSIL) Pictet, 1855 †
Emarginula multiradiata (FOSSIL) N.E. Weisbord, 1962 †
Hemitoma multiradiata (FOSSIL) Hislop, 1859 †
Emarginula multisquamosa M.M. Schepman, 1908
Cranopsis multistriata (W.H. Dall, 1914)
Emarginula multistriata J.G. Jeffreys, 1882
Macroschisma munita T. Iredale, 1940
Diodora murina R. Arnold, 1903
Diodora mus L.A. Reeve, 1850
Fissurella mutabilis G.B. I Sowerby, 1835
Diodora namibiensis G.T. Poppe, S.P. Tagaro& J. Sarino, 2011
Puncturella nana (C.B. Adams, 1872)
Fissuridea nassula (FOSSIL) T.A. Conrad, 1845 †
Emarginula natalensis K.H. Barnard, 1963
Fissurella natalensis C.F.F. von Krauss, 1848
Octomarginula natlandi (J.W. Durham, 1950)
Zeidora naufraga R.B. Watson, 1883
Tugali navicula (FOSSIL) Finlay, 1926 †