Neusas marshalli (E.R. Sykes, 1925)
Vitrinella martensiana (L.G. Hertlein& A.M. Strong, 1951)
Vitrinella massarita W.H. Dall, 1927
Episcynia medialis A.M. Keen, 1971
Circuitus medius Rubio & Rolán, 2017
Teinostoma megacallum F. Rubio, R. Fernández-Garcés& E. Rolán, 2011
Teinostoma megastoma (C.B. Adams, 1850)
Idioraphe mekon (FOSSIL) Gardner, 1947 †
Pseudoliotia micans (A. Adams, 1850)
Circulus microsculpturatus P.G. Oliver & E. Rolán,2011
Cyclostremiscus microstriatus F. Rubio, E. Rolán& Y.C. Lee, 2011
Tornus mienisi J.J. Van Aartsen, F. Carrozza& H.P.M.G. Menkhorst, 1998
Solariorbis miguelensis H.A. Pilsbry & A.A. Olsson,1952
Discopsis militare (F.P. Jousseaume, 1872)
Solariorbis millepunctatus (H.A. Pilsbry& A.A. Olsson, 1945)
Tuberes minituber Rubio & Rolán, 2017
Teinostoma minusculum (K.J. Bush, 1897)
Ponderinella minutissima E. Rolán & F. Rubio, 2002
Scrupus minutus (W.F. Petterd, 1884)
Solariorbis minutus (C.B. Adams, 1852)
Tornus miobicarinatus (FOSSIL) (F. Sacco, 1896 †)
Circulus mitis (FOSSIL) (G.P. Deshayes, 1862 †)
Vitrinella modesta C.B. Adams, 1852
Circulus modestus (A.A. Gould, 1859)
Cyclostremiscus mohicanus L.R.L. Simone, 2012
Parviturboides monile (P.P. Carpenter, 1857)
Parviturboides monilifer (P.P. Carpenter, 1857)
Circuitus monoplanes Rubio & Rolán, 2017
Teinostoma moodiense (FOSSIL) †
Solariorbis mooreanus E.G. Vanatta, 1904
Morchiella moreleti (P. Fischer, 1877)
Teinostoma morlierei F.P. Jousseaume, 1872
Laciniorbis morti T. Iredale, 1931
Circulus mortoni W.F. Ponder, 1994
Pseudoliotia motobuensis (FOSSIL) F.S. MacNeil, 1960 †