Coahuilix landyei R. Hershler, 1985
Heleobia languiensis (H. Hass, 1955)
Tryonia laqueata (FOSSIL) T.A. Conrad, 1871 †
Dyris lataguensis (FOSSIL) Wesselingh, 2006 †
Lyrodes latus (F. Haas, 1949)
Littoridina limariensis W.A. Biese, 1944
Littoridina limosa (H.B. Preston, 1915)
Dyris lintea (FOSSIL) T.A. Conrad, 1871 †
Littoridina lioneli (H.B. Preston, 1915)
Sioliella littoridinaeformis (FOSSIL) Wesselingh, 2006 †
Littoridina loaensis W.A. Biese, 1947
Emmericiella longa (H.A. Pilsbry, 1909)
Semisalsa longiscata (J.R. Bourguignat, 1856)
Eupaludestrina macei (A. Paladilhe, 1867)
Littoridina magallanica W.A. Biese, 1947
Rhamphopoma magnum F. Haas, 1955
Ramphopoma magnun H. Hass, 1955
Eupaludestrina maltzani (C.A. Westerlund, 1886)
Littoridina manni F.C. Baker, 1913
Tryonia margae R. Hershler, 1989
Tryonia mariae (J.P.E. Morrison, 1945)
Zetekina martensi (H.A. Pilsbry, 1935)
Dyris mattii (FOSSIL) Wesselingh, 2006 †
Dyris megacarinatus (FOSSIL) Wesselingh, 2006 †
Zetekina melanioides (E.C. Von Martens, 1899)
Tryonia metcalfi R. Hershler, H.P. Liu& J.J. Landye, 2011
Aroapyrgus mexicanus (H.A. Pilsbry, 1910)
Littoridina miaulis Er. Marcus & Ev. Marcus,1965
Dyris microbispiralis (FOSSIL) Wesselingh, 2006 †
Littoridina microcona F.G. Thompson & R. Hershler,1991
Onobops microconvexus (FOSSIL) Wesselingh, 2006 †
Dyris microturritella (FOSSIL) Wesselingh, 2006 †
Cochliopina milleri D.W. Taylor, 1966
Tryonia minckleyi R. Hershler, H.P. Liu& J.J. Landye, 2011
Onobops minissimus (FOSSIL) Wesselingh, 2006 †