Leptachatina microdon H.A. Pilsbry & C.M. Cooke,1914
Amastra mirabilis C.M. Cooke, 1917
Amastra modesta (C.B. Adams, 1851)
Amastra modicella C.M. Cooke, 1917
Amastra moesta (W. Newcomb, 1854)
Leptachatina molokaiensis C.M. Cooke, 1910
Amastra montagui H.A. Pilsbry, 1913
Amastra montana D.D. Baldwin, 1906
Amastra montivaga C.M. Cooke, 1917
Leptachatina morbida C.M. Cooke, 1911
Amastra morticina A. Hyatt & H.A. Pilsbry,1911
Amastra mucronata (W. Newcomb, 1853)
Amastra nana D.D. Baldwin, 1895
Amastra nannodes C.M. Cooke, 1933
Carelia necra C.M. Cooke, 1931
Amastra neglecta H.A. Pilsbry & C.M. Cooke,1914
Leptachatina nematoglypta H.A. Pilsbry & C.M. Cooke,1914
Amastra nigra W. Newcomb, 1855
Leptachatina nitida W. Newcomb, 1853
Amastra nubifera A. Hyatt & H.A. Pilsbry,1911
Amastra nubigena H.A. Pilsbry & C.M. Cooke,1914
Amastra nubilosa (J.W. Mighels, 1845)
Amastra nucleola (A.A. Gould, 1854)
Amastra nucula E.A. Smith, 1873
Amastra obesa (W. Newcomb, 1853)
Amastra obesa aurora H.A. Pilsbry & C.M. Cooke,1914
Leptachatina obsoleta L. Pfeiffer, 1857
Leptachatina obtusa L. Pfeiffer, 1856
Leptachatina octogyrata J.T. Gulick, 1856
Carelia olivacea W.H. Pease, 1866
Leptachatina omphalodes C.M.F. Ancey, 1899
Leptachatina opipara C.M. Cooke, 1910
Leptachatina optabilis C.M. Cooke, 1911
Leptachatina oryza L. Pfeiffer, 1856
Amastra oswaldi C.M. Cooke, 1933