Sigmesalia multisulcata (FOSSIL) (J.B.P.A. Lamarck,1804 †)
Maoricolpus murrayana (FOSSIL) (R. Tate, 1885 †)
Colpospira musgravia (T.A. Garrard, 1982)
Ispharina naimi (FOSSIL) Abbass, 1967 †
Turritella narica (FOSSIL) E.W. Vredenburg, 1928 †
Turritella nasuta (FOSSIL) †
Torquesia nazikae (FOSSIL) Awad & Abed, 1967 †
Turritella nebulosa L.C. Kiener, 1843
Turritella nelsoni (FOSSIL) E.M. Spieker, 1922 †
Turritella nerinexa (FOSSIL) G.F. Harris, 1895 †
Neohaustator nipponica (FOSSIL) M. Yokoyama, 1920 †
Zeacolpus nisseni (FOSSIL) J. Marwick, 1971 †
Turritella nivea H.E. Anton, 1838
Vermicularia nodosa C. Hedley, 1907
Turritella noetlingi (FOSSIL) E.W. Vredenburg, 1921 †
Tachyrhynchus nomurai (H. Ozaki, 1958)
Turritella nucleocostata W.L. May, 1915
Turritella nysti (FOSSIL) Briart & Cornet, 1887 †
Protoma obeliscus (FOSSIL) (J.P.S. Grateloup,1822 †)
Turritella obruta (FOSSIL) T.A. Conrad, 1833 †
Archimediella occidua (B.C. Cotton & N.H. Woods,1935)
Turritella ochlockoneensis (FOSSIL) W.C. Mansfield, 1930 †
Turritella ocoyana (FOSSIL) T.A. Conrad, 1855 †
Mariacolpus octonaria (FOSSIL) (T.A. Conrad, 1863 †)
Colpospira okadai T. Nagao
Turritella olssoni (FOSSIL) Clark & J.W. Durham,1946 †
Maoricolpus ongleyi (FOSSIL) J. Marwick, 1931 †
Mesalia opalina (A. Adams & L.A. Reeve,1849)
Mesalia opalina flammifera (É.A.A. Locard, 1897)
Mesalia opalina simplex É.A.A. Locard, 1897
Turritella opalina (FOSSIL) W. Adam & L.A. Reeve,1850 †
Zeacolpus opoitius (FOSSIL) J. Marwick, 1965 †
Glyptozaria opulenta (C. Hedley, 1907)
Turritella oregonensis (FOSSIL) (T.A. Conrad, 1849 †)
Turritella oreodoxa (FOSSIL) A.A. Olsson, 1922 †