Horologica macrometrica C.F. Laseron, 1956
Synthopsis mactanensis A. Cecalupo & I. Perugia,2012
Seila mactanensis A. Cecalupo & I. Perugia,2012
Seila maculosa C.F. Laseron, 1951
Marshallopsis maesta A. Cecalupo & I. Perugia,2012
Joculator maestratii (FOSSIL) P. Lozouet, Lesport& Renard, 2001 †
Synthopsis maestratii A. Cecalupo & I. Perugia,2012
Clathropsis mafeaensis A. Cecalupo & I. Perugia,2013
Cerithiopsis magellanica P. Bartsch, 1911
Seila magna C.F. Laseron, 1951
Horologica magnifica A. Cecalupo & I. Perugia,2012
Joculator magninensis Cecalupo & Perugia, 2017
Joculator maloensis A. Cecalupo & I. Perugia,2013
Seila maoria B.A. Marshall, 1978
Joculator maranii A. Cecalupo & I. Perugia,2014
Mendax marginata (H.H. Suter, 1908)
Horologica marianii A. Cecalupo & I. Perugia,2012
Cerithiopsis marileutes (J.C. Melvill & R. Standen,1895)
Joculator marinae A. Cecalupo & I. Perugia,2014
Clathropsis maritima C.F. Laseron, 1956
Seila marmorata (R. Tate, 1893)
Clathropsis marshalli Cecalupo & Perugia, 2017
Cerithiopsis martensis W.H. Dall, 1881
Horologica martini M. Jay & J. Drivas, 2002
Mendax mascarenensis M. Jay & J. Drivas, 2002
Joculator massimilianoi A. Cecalupo & I. Perugia,2012
Cerithiopsis matara W.H. Dall, 1889
Cerithiopsis mathildaeformis J.C. Melvill, 1906
Tubercliopsis maxi A. Cecalupo & I. Perugia,2012
Seila maxima A. Cecalupo & I. Perugia,2014
Joculator mbereensis Cecalupo & Perugia, 2017
Joculator meanii A. Cecalupo & I. Perugia,2014
Joculator megacephala M. Jay & J. Drivas, 2002
Cerithiopsis mekranica (FOSSIL) E.W. Vredenburg, 1928 †
Marshallopsis melanesiana A. Cecalupo & I. Perugia,2013