Ranularia oboesa (G. Perry, 1811)
Ranularia oboesa retusa J.B.P.A. Lamarck, 1822
Septa occidentalis O.A.L. Mörch, 1877
Septa occidentalis beui F. García-Talavera, 1985
Septa ogygia (FOSSIL) W.P. Woodring, 1959 †
Ranella olearium (C. Linnaeus, 1758)
Ranella olearium atlantica T.A. de M. Monterosato,1890
Ranella olearium barcellosi H.R. Matthews, E. de C. Rios& A.C. dos Santos Coelho, 1973
Charonia oligostirus (FOSSIL) R. Tate, 1888 †
Fusitriton oregonensis (J.H. Redfield, 1846)
Charonia ovoideus (FOSSIL) R. Tate, 1888 †
Sassia pahaoaensis (FOSSIL) (P. Vella, 1954 †)
Gelagna pallida (M. Parth, 1996)
Sassia palmeri (A.W.B. Powell, 1967)
Monoplex panamensis (FOSSIL) A.G. Beu, 2010 †
Obscuranella papyrodes Y.I. Kantor& M.G. Harasewych, 2000
Sassia parkinsonia (G. Perry, 1811)
Monoplex parthenopeus (C.U.A. von Salis-Marschlins, 1793)
Monoplex parthenopeus echo J.T. Kuroda & T. Habe,1961
Monoplex parthenopeus robusta B.H. Belletante, 1954
Ranularia parthi (A. Arthur, 1991)
Sassia parvula (FOSSIL) (O.G. Michelotti, 1847 †)
Septa peasei (A.G. Beu, 1987)
Monoplex penniketi (A.G. Beu, 1998)
Biplex perca (G. Perry, 1811)
Biplex perliberalis (FOSSIL) C. Beets, 1984 †
Lotoria perryi (Perry, 1811)
Sassia petulans (C. Hedley & W.L. May,1908)
Reticutriton pfeifferianus (L.A. Reeve, 1844)
Sassia philomelae Watson, 1881
Monoplex pilearis (C. Linnaeus, 1758)
Monoplex pilearis martinianum D'Orbigny, 1846
Charonia pilula (FOSSIL) (A.E.M. Cossmann, 1897 †)
Sassia planicostata (FOSSIL) (G.P. Deshayes, 1835 †)
Sassia polygonoides (FOSSIL) (G.P. Deshayes, 1865 †)