Joculator melania C.F. Laseron, 1956
Joculator melanoraphis M. Jay & J. Drivas, 2002
Clathropsis mellita C.F. Laseron, 1956
Cerithiopsis melvilli M. Jay & J. Drivas, 2002
Prolixodens memorabilis A. Cecalupo & I. Perugia,2012
Synthopsis memorabilis A. Cecalupo & I. Perugia,2012
Cerithiopsis merida W.H. Dall, 1927
Mendax metivieri M. Jay & J. Drivas, 2002
Horologica micaelae A. Cecalupo & I. Perugia,2012
Cerithiopsis micalii (A. Cecalupo & A. Villari,1997)
Joculator micalii A. Cecalupo & I. Perugia,2012
Horologica minareta C.F. Laseron, 1956
Cerithiopsis minima (Š. Brusina, 1865)
Joculator minimus C.F. Laseron, 1956
Joculator minor C.F. Laseron, 1956
Tubercliopsis minor A. Cecalupo & I. Perugia,2012
Cerithiopsis minuata (FOSSIL) G.P. Deshayes, 1864 †
Joculator minutissimus (K.H.J. Thiele, 1925)
Joculator minutus A. Cecalupo & I. Perugia,2012
Synthopsis mirabilis A. Cecalupo & I. Perugia,2012
Tubercliopsis miranda A. Cecalupo & I. Perugia,2012
Joculator modestus A. Cecalupo & I. Perugia,2012
Cerithiopsis montereyensis P. Bartsch, 1911
Seila montereyensis P. Bartsch, 1907
Cerithiopsis montezumai A.M. Strong & L.G. Hertlein,1939
Horologica montii A. Cecalupo & I. Perugia,2013
Prolixodens montrouzieri Cecalupo & Perugia, 2017
Cerithiopsis morelosensis E. Rolán& R. Fernández-Garcés, 2010
Joculator morenae A. Cecalupo & I. Perugia,2013
Joculator morigii Cecalupo & Perugia, 2017
Seila morishimai (T. Habe, 1970)
Cerithiopsis moritzhoernesi (FOSSIL) B.M. Landau, F. Da Silva& S.M. Heitz, 2016 †
Cerithiopsis movilla W.H. Dall & P. Bartsch,1911
Cerithiopsis mucro (FOSSIL) (C.R. Laws, 1939 †)
Clathropsis multispirae A. Cecalupo & I. Perugia,2012