Sveltia lyrata (G.B. Brocchi, 1814)
Microsveltia machaira A. Verhecken, 2011
Cancellaria macnairyensis (FOSSIL) N.F. Sohl, 1964 †
Pyruclia macneili (FOSSIL) W.C. Mansfield, 1937 †
Fusiaphera macrospira (A. Adams & L.A. Reeve,1850)
Fusiaphera macrospira macrospiratoides (A. Adams & L.A. Reeve,1850)
Fusiaphera macrospira producta (A. Adams & L.A. Reeve,1850)
Mirandaphera maestratii P. Bouchet & R.E. Petit,2002
Admete magellanica (H. Strebel, 1905)
Plesiocerithium maglorii (FOSSIL) (Melleville, 1843 †)
Zeadmete major (FOSSIL) (J. Marwick, 1965 †)
Cancellaria major P.M. Pallary, 1900
Sveltia major (FOSSIL) H.F.A. von Ihering,1899 †
Euclia maldonadoi (FOSSIL) A.A. Olsson, 1964 †
Scalptia maoria (FOSSIL) (P. Marshall& R. Murdoch, 1921 †)
Coptostoma marcominii (FOSSIL) P. Lozouet, 2015 †
Tritonoharpa mariechristinae Lesport, Cluzaud& A. Verhecken, 2015
Merica marisca P. Bouchet & R.E. Petit,2002
Hertleinia marksi (FOSSIL) A.A. Olsson, 1964 †
Admetula marshalli P. Bouchet & R.E. Petit,2008
Fusiaphera marshalli (FOSSIL) (R.S. Allan, 1926 †)
Inglisella marshalli (FOSSIL) (L. Vignal, 1921 †)
Ventrilia marthae (FOSSIL) A.A. Olsson, 1967 †
Bivetia martini (FOSSIL) A.E.M. Cossmann, 1899 †
Inglisella marwicki (R.K. Dell, 1956)
Admete marylandica (FOSSIL) G.C. Martin, 1904 †
Marianarona marylandica (FOSSIL) E.J. Petuch, 1988 †
Cancellaria mauryae (FOSSIL) A.A. Olsson, 1922 †
Cancellaria mediamericana E.J. Petuch, 1998
Cancellaria medicinensis (FOSSIL) (Cragin, 1894 †)
Cancellaria medinae (FOSSIL) R.A. Philippi, 1887 †
Merica melanostoma (G.B. II Sowerby, 1849)
Merica melanostoma westralis (T.A. Garrard, 1975)
Scalptia mercadoi W.E. Old, 1968
Colubratriton merlei (FOSSIL) J.M. Pacaud, Ledon& Loubry, 2015 †