Succincta oaxacana H.A. Pilsbry, 1920
Helicina occidentalis L. Guilding, 1828
Hendersonia occulta (T. Say, 1831)
Ogasawarana ogasawarana (H.A. Pilsbry, 1902)
Ogasawarana optima (A.J. Wagner, 1905)
Olygyra orbiculata (T. Say, 1818)
Olygyra orbiculata tropica L. Pfeiffer, 1852
Helicina oskari A.J. Wagner, 1911
Aphanoconia osumiense (H.A. Pilsbry, 1901)
Helicina ouenensis T.D.A. Cockerell, 1930
Succincta oweniana (L. Pfeiffer, 1849)
Oxyrhombus oxyrhyncha (J.C.H. Crosse& E.O. Debeaux, 1863)
Helicina oxytropis G.B. Sowerby, 1838
Geophorus oxytropis (J.E. Gray, 1839)
Aphanoconia pachystoma (E.A. Smith, 1896)
Orobophana pacifica (W.H. Pease, 1865)
Helicina pallida A.A. Gould, 1847
Schasicheila palmeri W.H. Dall, 1905
Schasicheila pannucea (P.M.A. Morelet, 1849)
Helicina papyracea (W.J. Broderip, 1841)
Alcadia paraensis (L. Pfeiffer, 1859)
Sulfurina parva (G.B. Sowerby, 1842)
Sturanya parvula (W.H. Pease, 1868)
Helicina pazi J.C.H. Crosse, 1865
Lucidella peasei H.A. Pilsbry, 1933
Pleuropoma pelewensis (E.R. Sykes, 1901)
Lucidella persculpta H.A. Pilsbry & A.P. Brown,1912
Helicina peruviana P.M.A. Morelet, 1863
Troschelviana petitiana (A.V.M.D. D'Orbigny,1842)
Troschelviana pfeifferiana (R. Arango in L. Pfeiffer,1866)
Helicina phakos A.J. Wagner, 1911
Lewisia philippiana (C.B. Adams, 1851)
Ceochasma phrixina F.G. Thompson, 1968
Palaeohelicina phronema A.J. Wagner, 1905
Fadyenia pickeringiana E. Chitty, 1857