- ocicula, Acanthochitona ocicula P.P. Carpenter - (ACANTHOCHITONIDAE)
- Ocinebra, syn of: Genus Ocenebra J.E. Gray, 1847 (MURICIDAE)
- Ocinebrellus, Subgenus Pteropurpura (Ocinebrellus) F.P. Jousseaume, 1880 (MURICIDAE)
- Ocinebrina, Genus Ocinebrina F.P. Jousseaume, 1880 (MURICIDAE)
- ocirrhoe, Cerithium ocirrhoe Orbigny, 1852 † - (CERITHIIDAE) (FOSSIL)
- ockelmani, Dacrydium ockelmani Mattson & A. Warén, 1977 - syn of: Dacrydium ockelmanni Mattson & A. Warén, 1977 - (MYTILIDAE)
- ockelmanni, Dacrydium ockelmanni Mattson & A. Warén, 1977 - (MYTILIDAE)
- ockelmanni, Mendicula ockelmanni (Keuning & C.F.C. Schander, 2010) - (THYASIRIDAE)
- ockelmanni, Thyasira ockelmanni Keuning & C.F.C. Schander, 2010 - syn of: Mendicula ockelmanni (Keuning & C.F.C. Schander, 2010) - (THYASIRIDAE)
- ocklockoneensis, Pecten ocklockoneensis (W.C. Mansfield, 1932 †) - (PECTINIDAE) (FOSSIL)
- ocloya, Pisidium ocloya C.F. Ituarte, 2005 - (SPHAERIIDAE)
- ocnera, Anodonta ocnera G. Servain, 1882 - syn of: Anodonta cygnea (C. Linnaeus, 1758) - (UNIONIDAE)
- ocnerella, Anodonta ocnerella G. Servain - syn of: Anodonta cygnea (C. Linnaeus, 1758) - (UNIONIDAE)
- ocoae, Glyphyalinia ocoae L.R. Hubricht, 1978 - (ZONITIDAE)
- ocoeensis, Elimia ocoeensis (I. Lea, 1868) - (PLEUROCERIDAE)
- oconaensis, Patinigera oconaensis DeVries, 2007 † - (NACELLIDAE) (FOSSIL)
- oconnellensis, Sphaerospira oconnellensis J.C. Cox, 1871 - (CAMAENIDAE)
- oconnori, Echinophoria oconnori (R.K. Dell, 1952 †) - (CASSIDAE) (FOSSIL)
- oconnori, Cavellia oconnori R.K. Dell, 1950 - (CHAROPIDAE)
- oconnori, Phacussa oconnori A.W.B. Powell, 1941 - (CHAROPIDAE)
- oconnori, Glyptophysa oconnori (R.A. Cumber, 1941) - (PLANORBIDAE)
- oconnori, Physastra oconnori R.A. Cumber, 1941 - syn of: Glyptophysa oconnori (R.A. Cumber, 1941) - (PLANORBIDAE)
- oconnori, Rhytida oconnori A.W.B. Powell, 1946 - (RHYTIDIDAE)
- oconnori, Powelliphanta lignaria oconnori (A.W.B. Powell, 1938) - (RHYTIDIDAE)
- ocoyana, Olcesia ocoyana (T.A. Conrad, 1855 †) - (TELLINIDAE) (FOSSIL)
- ocoyana, Turritella ocoyana T.A. Conrad, 1855 † - (TURRITELLIDAE) (FOSSIL)
- ocoyanum, Trophosycon ocoyanum (T.A. Conrad †) - (FICIDAE) (FOSSIL)
- ocrea, Serpula ocrea J.F. Gmelin, 1791 - syn of: Thylacodes colubrinus (P.F. Röding, 1798) - (VERMETIDAE)
- ocrea, Serpulorbis ocrea J.F. Gmelin, 1791 - syn of: Thylacodes colubrinus (P.F. Röding, 1798) - (VERMETIDAE)
- ocresanus, Unio ocresanus É.A.A. Locard, 1899 - syn of: Unio abrantesianus É.A.A. Locard, 1899 - (UNIONIDAE)
- ocrinium, Cyclostrema ocrinium J.C. Melvill & R. Standen, 1901 - (LIOTIIDAE)
- ocrinum, Cyclostrema ocrinum J.C. Melvill & R. Standen, 1901 - syn of: Cyclostrema ocrinium J.C. Melvill & R. Standen, 1901 - (LIOTIIDAE)
- ocrophaius, Modiolus ocrophaius A.E.M. Cossmann, 1887 † - (MYTILIDAE) (FOSSIL)
- Ocruranus, Genus Ocruranus Liu, 1979 † (HALKIERIIDAE) (FOSSIL)
- ocsensis, Valvata ocsensis L. Soós, 1934 † - (VALVATIDAE) (FOSSIL)
- ocsensis, Vertigo ocsensis (Halaváts, 1903) † - (VERTIGINIDAE) (FOSSIL)
- ocsensis halavatsi, Valvata ocsensis halavatsi (Gozhik, 2002 †) - (VALVATIDAE) (FOSSIL)
- Octadenia, Subgenus Cepaea (Octadenia) A.A. Schileyko, 1978 (HELICIDAE)
- Octadenia, syn of: Subgenus Metafruticicola (Caucasocressa) P. Hesse, 1921 ? (HYGROMIIDAE)
- octagona, Diodora octagona (L.A. Reeve, 1850) - (FISSURELLIDAE)
- octagona, Fissurella octagona L.A. Reeve, 1850 - syn of: Diodora octagona (L.A. Reeve, 1850) - (FISSURELLIDAE)
- octagona reevei, Diodora octagona reevei (M.M. Schepman, 1908) - (FISSURELLIDAE)
- octagonum, Dentalium octagonum J.B.P.A. Lamarck - (DENTALIIDAE)
- octagonum, Epitonium octagonum (G.B. III Sowerby, 1905) - (EPITONIIDAE)
- octagonus, Murexsul octagonus (J.R.C. Quoy & J.P. Gaimard, 1834) - (MURICIDAE)
- octagonus, Theodoxus octagonus Eichhorst, 2016 - (NERITIDAE)
- Octamerella, Genus Octamerella Teichert & Sweet, 1962 † (HEMIPHRAGMOCERATIDAE) (FOSSIL)
- Octameroceras, Genus Octameroceras Hyatt & Zittel, 1900 † (HEMIPHRAGMOCERATIDAE) (FOSSIL)
- octana, Subulina octana J.G. Bruguière, 1792 - syn of: Subulina octona (J.G. Bruguière, 1792) - (SUBULINIDAE)
- octanfracta, Laemodonta octanfracta (I.H. Jonas, 1845) - (ELLOBIIDAE)
- octangulata, Hemicythara octangulata (R.W. Dunker, 1860) - (MANGELIIDAE)
- octangulatum, Dentalium octangulatum E. Donovan, 1804 - (DENTALIIDAE)
- octaploidus, Bulinus octaploidus J.B. Burch, 1972 - (PLANORBIDAE)
- octaporosa, Octoporia octaporosa (J.A. Allen & R.E. Morgan, 1981) - (CUSPIDARIIDAE)
- octava, Ningbingia octava G.A. Solem, 1981 - (CAMAENIDAE)
- octava, Carinigera octava R.A.M. Brandt, 1962 - (CLAUSILIIDAE)
- octavia, Poleumita octavia (A.V.M.D. D'Orbigny, 1850 †) - (EUOMPHALIDAE) (FOSSIL)
- octavia, Oxytoma octavia (A.V.M.D. D'Orbigny, 1850 †) - (OXYTOMIDAE) (FOSSIL)
- octavia, Pinna octavia J. Marwick, 1953 † - (PINNIDAE) (FOSSIL)
- octavia minuta, Poleumita octavia minuta Pitcher † - (EUOMPHALIDAE) (FOSSIL)
- octaviae, Frechiella octaviae Renz, 1925 † - (HILDOCERATIDAE) (FOSSIL)
- octaviana, Emarginula octaviana G.S. Coen, 1939 - (FISSURELLIDAE)
- octaviana, Pyramidella octaviana S.I. Di Geronimo, 1973 - syn of: Tiberia minuscula (T.A. de M. Monterosato, 1880) - (PYRAMIDELLIDAE)
- octavii, Acteon octavii (Vasseur, 1881 †) - (ACTEONIDAE) (FOSSIL)
- octavium, Gyronema octavium A.V.M.D. D'Orbigny, 1850 † - syn of: Poleumita octavia (A.V.M.D. D'Orbigny, 1850 †) - (LOPHOSPIRIDAE) (FOSSIL)
- octavula, Achatinella octavula F. Paetel - syn of: Leptachatina sandwicensis (L. Pfeiffer, 1846) - (ACHATINELLIDAE)
- octerlonii, Paracyclas octerlonii Nettelroth † - (PARACYCLIDAE) (FOSSIL)
- octoangulata, Tofanella octoangulata Grundel, 2006 † - (TOFANELLIDAE) (FOSSIL)
- octocarinatus, Trichosirius octocarinatus (A.W.B. Powell, 1931) - (CAPULIDAE)
- octocarinatus, Ariadnaria octocarinatus A.W.B. Powell, 1931 - syn of: Trichosirius octocarinatus (A.W.B. Powell, 1931) - (CAPULIDAE)
- octocinctus, Roemeriella octocinctus (A. Römer, 1843 †) - (PSEUDOPHORIDAE) (FOSSIL)
- octocinctus, Turbo octocinctus A. Römer, 1843 † - syn of: Roemeriella octocinctus (A. Römer, 1843 †) - (TURBINIDAE) (FOSSIL)
- octocostata, Asperiscala octocostata O.A.L. Mörch, 1875 - syn of: Epitonium denticulatum (G.B. II Sowerby, 1844) - (EPITONIIDAE)
- octocostata, Epitonium octocostata O.A.L. Mörch, 1875 - syn of: Epitonium denticulatum (G.B. II Sowerby, 1844) - (EPITONIIDAE)
- octocostatum, Procerithium octocostatum Yamnichenko, 1987 † - syn of: Neocryptaulax mutabilis (Gerasimov & al., 1996 †) - (PROCERITHIIDAE) (FOSSIL)
- octocostatus, Permophorus octocostatus (Weller, 1916 †) - (KALENTERIDAE) (FOSSIL)
- octodecimliratum, Propeamussium octodecimliratum (J.C. Melvill & R. Standen, 1907) - (PROPEAMUSSIIDAE)
- octodentata, Vertigo octodentata C.A. Westerlund, 1878 - syn of: Vertigo moulinsiana (D. Dupuy, 1849) - (VERTIGINIDAE)
- octodentata, Vertigo octodentata S.E. Studer, 1820 - syn of: Vertigo antivertigo J.P.R. Draparnaud, 1801 - (VERTIGINIDAE)
- octodentatum, Anostoma octodentatum G. Fischer von Waldheim, 1807 - (ODONTOSTOMIDAE)
- octodentatum brunneum, Anostoma octodentatum brunneum (B. Verdcourt, 1990) - (ODONTOSTOMIDAE)
- octodentatum depressum, Anostoma octodentatum depressum J.B.P.A. Lamarck, 1822 - (ODONTOSTOMIDAE)
- octodentatum verreauxianum, Anostoma octodentatum verreauxianum L.H. Hupé, 1857 - (ODONTOSTOMIDAE)
- octoglandulosa, Ponentina octoglandulosa D.T. Holyoak & G.A. Holyoak, 2012 - (HYGROMIIDAE)
- octogna, Subulina octogna J.G. Bruguière, 1792 - syn of: Subulina octona (J.G. Bruguière, 1792) - (SUBULINIDAE)
- octogona, Diodora octogona L.A. Reeve, 1850 - syn of: Diodora octagona (L.A. Reeve, 1850) - (FISSURELLIDAE)
- octogona, Subulina octogona J.G. Bruguière, 1792 - syn of: Subulina octona (J.G. Bruguière, 1792) - (SUBULINIDAE)
- octogonalis, Cymbiola nobilis octogonalis J.R. Senders, 1995 - (VOLUTIDAE)
- octogonatus, Muricopsis octogonatus (J.R.C. Quoy & J.P. Gaimard, 1833 †) - (MURICIDAE) (FOSSIL)
- octogonum, Dentalium octogonum J.B.P.A. Lamarck, 1818 - syn of: Dentalium octangulatum E. Donovan, 1804 - (DENTALIIDAE)
- octogonus, Murexsul octogonus (J.R.C. Quoy & J.P. Gaimard, 1833) - (MURICIDAE)
- octogonus, Murex octogonus G.B. II Sowerby, 1860 - syn of: Favartia humilis (W.J. Broderip, 1833) - (MURICIDAE)
- octogonus, Pyrazus octogonus Cox, 1930 † - (POTAMIDIDAE) (FOSSIL)
- octogyra, Stenogyra octogyra (L. Pfeiffer, 1856) - (SUBULINIDAE)
- octogyrata, Achatinella octogyrata J.T. Gulick - syn of: Leptachatina octogyrata J.T. Gulick, 1856 - (ACHATINELLIDAE)
- octogyrata, Leptachatina octogyrata J.T. Gulick, 1856 - (AMASTRIDAE)
- octolamellata, Taipidon octolamellata (A. Garrett, 1887) - (ENDODONTIDAE)
- octolineata, Enoploteuthis octolineata C.M. Burgess, 1982 - (ENOPLOTEUTHIDAE)
- octolirata, Circulus octolirata (P.P. Carpenter, 1856) - (TORNIDAE)
- octoliratus, Napulus octoliratus (T.A. Conrad, 1858 †) - (TURBINELLIDAE) (FOSSIL)
- Octomarginula, Genus Octomarginula J.H. McLean, 2011 (FISSURELLIDAE)
- octona, Cecilioides octona E.C. Von Martens, 1901 - (FERUSSACIIDAE)
- octona, Helix octona J.G. Bruguière, 1789 - syn of: Subulina octona (J.G. Bruguière, 1792) - (HELICIDAE)
- octona, Hydrobia octona (J.G. Bruguière, 1792) - (HYDROBIIDAE)
- octona, Turbonilla octona R.J.L. Guppy, 1896 - syn of: Bacteridium resticulum (W.H. Dall, 1889) - (PYRAMIDELLIDAE)
- octona, Subulina octona (J.G. Bruguière, 1792) - (SUBULINIDAE)
- octona, Strialuna octona (J.G. Bruguière, 1789) - (THYSANOPHORIDAE)
- octona, Leiopyrga octona (R. Tate, 1891) - (TROCHIDAE)
- octona problematica, Leiopyrga octona problematica T. Iredale, 1924 - syn of: Leiopyrga octona (R. Tate, 1891) - (TROCHIDAE)
- octona strebeli, Subulina octona strebeli E.C. Von Martens, 1898 - syn of: Subulina octona (J.G. Bruguière, 1792) - (SUBULINIDAE)
- octonaria, Gastrocopta octonaria H.A. Pilsbry, 1924 - (GASTROCOPTIDAE)
- octonaria, Muellerpalia haszprunari octonaria (Š. Brusina, 1902 †) - (HYDROBIIDAE) (FOSSIL)
- octonaria, Mariacolpus octonaria (T.A. Conrad, 1863 †) - (TURRITELLIDAE) (FOSSIL)
- octonoides, Bulimus octonoides D'Orbigny, 1841 - syn of: Allopeas gracilis (F.W. Hutton, 1834) - (BULIMULIDAE)
- octonoides, Bulimus octonoides C.B. Adams, 1845 - syn of: Leptopeas micra (A.V.M.D. D'Orbigny, 1835) - (BULIMULIDAE)
- octonoides, Opeas octonoides C.B. Adams, 1845 - syn of: Leptopeas micra (A.V.M.D. D'Orbigny, 1835) - (SUBULINIDAE)
- octonoides subovale, Opeas octonoides subovale E.C. Von Martens, 1898 - syn of: Leptopeas micra (A.V.M.D. D'Orbigny, 1835) - (SUBULINIDAE)
- octonus, Murex octonus G.B. II Sowerby, 1834 - syn of: Hexaplex angularis (J.B.P.A. Lamarck, 1822) - (MURICIDAE)
- octonus, Murex octonus J.E. Gray in G.B. II Sowerby, 1841 - syn of: Murexsul dipsacus (W.J. Broderip, 1833) - (MURICIDAE)
- octopedatus, Gonatopsis octopedatus M. Sasaki, 1920 - (GONATIDAE)
- octoplectus, Pecten octoplectus Münster, 1841 † - syn of: Pecten protei Münster, 1841 † - (PECTINIDAE) (FOSSIL)
- octopleuron, Paradentalium octopleuron (J.C. Verco, 1911) - (DENTALIIDAE)
- octoplicata, Solatopupa octoplicata M. Lessona, 1880 - syn of: Solatopupa similis (J.G. Bruguière, 1792) - (CHONDRINIDAE)
- octoplicata, Topaginella octoplicata (J.E. Tenison-Woods, 1877 †) - (CYSTISCIDAE) (FOSSIL)
- octoplicata, Marginella octoplicata J.E. Tenison-Woods, 1877 † - syn of: Topaginella octoplicata (J.E. Tenison-Woods, 1877 †) - (MARGINELLIDAE) (FOSSIL)
- octoploidus, Bulinus octoploidus J.B. Burch, 1972 - syn of: Bulinus octaploidus J.B. Burch, 1972 - (PLANORBIDAE)
- OCTOPODA (UNASSIGNED) - Family (CEPHALOPODA-COLEOIDEA [Subclass]-OCTOPODIFORMES [Superorder]-OCTOPODA [Order]) (FOSSIL)
- octopodia, Eledone octopodia C. Linnaeus, 1758 - syn of: Eledone cirrhosa (J.B.P.A. Lamarck, 1798) - (OCTOPODIDAE)
- octopodia, Octopus octopodia G.W. Tryon, 1879 - syn of: Octopus vulgaris G.L.C.F.D. Cuvier, 1797 - (OCTOPODIDAE)
- octopodia, Sepia octopodia C. Linnaeus, 1758 - syn of: Eledone cirrhosa (J.B.P.A. Lamarck, 1798) - (SEPIIDAE)
- OCTOPODIDAE d'Orbigny, 1839 - Family (CEPHALOPODA-COLEOIDEA [Subclass]-OCTOPODIFORMES [Superorder]-OCTOPODA [Order]-INCIRRATA [Suborder]-OCTOPODOIDEA [Superfamily])
- OCTOPODOTEUTHIDAE - syn of Family: OCTOPOTEUTHIDAE
- Octopodoteuthis, syn of: Genus Octopoteuthis W.P.E.S. Rüppell, 1844 (OCTOPOTEUTHIDAE)
- Octopodoteuthopsis, syn of: Genus Octopoteuthis W.P.E.S. Rüppell, 1844 (OCTOPOTEUTHIDAE)
- Octoporia, Genus Octoporia O.A. Scarlato & Y.I. Starobogatov, 1983 (CUSPIDARIIDAE)
- OCTOPOTEUTHIDAE Berry, 1912 - Family (CEPHALOPODA-COLEOIDEA [Subclass]-DECAPODIFORMES [Superorder]-OEGOPSIDA [Order])
- Octopoteuthis, Genus Octopoteuthis W.P.E.S. Rüppell, 1844 (OCTOPOTEUTHIDAE)
- octopterygius, Glaucus octopterygius G.L.C.F.D. Cuvier, 1805 - syn of: Glaucus atlanticus F. Forster, 1777 - (GLAUCIDAE)
- Octopus, Genus Octopus G.L.C.F.D. Cuvier, 1797 (OCTOPODIDAE)
- octopus, Sepia octopus J.F. Gmelin, 1791 - syn of: Octopus vulgaris G.L.C.F.D. Cuvier, 1797 - (SEPIIDAE)
- octoradiata, Hemitoma octoradiata (J.F. Gmelin, 1791) - (FISSURELLIDAE)
- octoradiata, Patella octoradiata F.W. Hutton, 1873 - syn of: Scutellastra chapmani (J.E. Tenison-Woods, 1875) - (PATELLIDAE)
- octoradiata, Patella octoradiata (J.F. Gmelin, 1791) - syn of: Hemitoma octoradiata (J.F. Gmelin, 1791) - (PATELLIDAE)
- octosectus, Petaloconchus octosectus P.P. Carpenter, 1857 - (VERMETIDAE)
- octosulcata, Puzosia octosulcata (Sharpe, 1857 †) - (DESMOCERATIDAE) (FOSSIL)
- octosulcata, Gibbula octosulcata (P. Nyst, 1835 †) - (TROCHIDAE) (FOSSIL)
- octotentaculata, Divariscintilla octotentaculata P.M. Mikkelsen & R. Bieler, 1992 - (GALEOMMATIDAE)
- ocula, Doryteuthis ocula (A. Cohen, 1976) - (LOLIGINIDAE)
- ocula, Loligo ocula A. Cohen, 1976 - syn of: Doryteuthis ocula (A. Cohen, 1976) - (LOLIGINIDAE)
- ocula, Keeneia ocula (Sowerby, 1838 †) - (PLATYCERATIDAE) (FOSSIL)
- oculata, Glossodoris oculata (S. Delle Chiaje, 1841) - (CHROMODORIDIDAE)
- oculata, Cryptoplax oculata (J.R.C. Quoy & J.P. Gaimard, 1835) - (CRYPTOPLACIDAE)
- oculata, Erosaria oculata G.E. Rumphius, 1705 - syn of: Erosaria erosa (C. Linnaeus, 1758) - (CYPRAEIDAE)
- oculata, Mauritia oculata P.F. Röding, 1798 - syn of: Mauritia histrio (J.F. Gmelin, 1791) - (CYPRAEIDAE)
- oculata, Tucetona oculata (L.A. Reeve, 1843) - (GLYCYMERIDIDAE)
- oculata, Ptygmatis oculata C.F. Parona, 1896 † - (NERINEIDAE) (FOSSIL)
- oculata, Nuculana oculata T. Iredale, 1925 - (NUCULANIDAE)
- oculata, Terebra oculata J.B.P.A. Lamarck, 1822 - syn of: Terebra guttata (P.F. Röding, 1798) - (TEREBRIDAE)
- oculatum, Buccinum oculatum L.W. Dillwyn, 1817 - syn of: Terebra guttata (P.F. Röding, 1798) - (BUCCINIDAE)
- oculatum, Erosaria oculatum G.E. Rumphius, 1705 - syn of: Erosaria erosa (C. Linnaeus, 1758) - (CYPRAEIDAE)
- oculatus, Ammonites oculatus J. Phillips, 1829 † - (AMMONITIDA (UNASSIGNED)) (FOSSIL)
- oculatus, Chiton oculatus J.R.C. Quoy & J.P. Gaimard, 1835 - syn of: Cryptoplax larvaeformis (E.J. Burrow, 1815) - (CHITONIDAE)
- oculatus, Conus oculatus J.F. Gmelin, 1791 - syn of: Chelyconus ermineus (I. von Born, 1778) - (CONIDAE)
- oculatus, Cryptoplax oculatus J.R.C. Quoy & J.P. Gaimard, 1835 - syn of: Cryptoplax oculata (J.R.C. Quoy & J.P. Gaimard, 1835) - (CRYPTOPLACIDAE)
- oculatus, Pectunculus oculatus L.A. Reeve, 1843 - syn of: Tucetona oculata (L.A. Reeve, 1843) - (GLYCYMERIDIDAE)
- oculatus, Phyllonotus oculatus (L.A. Reeve, 1845) - (MURICIDAE)
- oculatus, Murex oculatus L.A. Reeve, 1845 - syn of: Phyllonotus oculatus (L.A. Reeve, 1845) - (MURICIDAE)
- oculatus, Phymorhynchus oculatus S.-Q. Zhang & S.-P. Zhang, 2017 - (RAPHITOMIDAE)
- oculeum, Chondropoma oculeum G.T. Watters & G. Duffy, 2010 - (POMATIIDAE)
- oculifer, Octopus oculifer W.E. Hoyle, 1904 - (OCTOPODIDAE)
- oculifera, Aplysia oculifera A. Adams & L.A. Reeve, 1850 - (APLYSIIDAE)
- oculifera, Coccopigya oculifera B.A. Marshall, 1986 - (COCCULINIDAE)
- oculifera, Gymnobela oculifera Y.I. Kantor & A.V. Sysoev, 1986 - (RAPHITOMIDAE)
- oculifera, Sepia oculifera A. de Rochebrune, 1884 - syn of: Sepia hierredda P.C.A.S.L. Rang, 1837 - (SEPIIDAE)
- oculis, Pilaflexis oculis C.F. Laseron, 1951 - (CERITHIOPSIDAE)
- oculisfictis, Cerithiopsis oculisfictis J. Prkic & P. Mariottini, 2010 - syn of: Potenatomus nanus (C.F. Laseron, 1951) - (CERITHIOPSIDAE)
- ocultabanda, Luciellina ocultabanda B.S. Kues & Batten, 2001 † - (GOSSELETINIDAE) (FOSSIL)
- oculus, Dermatobranchus oculus T.M. Gosliner & S.J. Fahey, 2011 - (ARMINIDAE)
- oculus, Aegista oculus (L. Pfeiffer, 1850) - (BRADYBAENIDAE)
- oculus, Euomphalus oculus Sowerby, 1838 † - syn of: Keeneia ocula (Sowerby, 1838 †) - (EUOMPHALIDAE) (FOSSIL)
- oculus, Lucina oculus Blake & Hudleston † - (LUCINIDAE) (FOSSIL)
- oculus, Cymbula oculus (I. von Born, 1778) - (PATELLIDAE)
- oculus, Patella oculus J.F. Gmelin, 1791 - syn of: Cymbula oculus (I. von Born, 1778) - (PATELLIDAE)
- oculus, Siphonaria oculus C.F.F. von Krauss, 1848 - (SIPHONARIIDAE)
- oculus, Trochus oculus Sowerby, 1838 † - syn of: Keeneia ocula (Sowerby, 1838 †) - (TROCHIDAE) (FOSSIL)
- oculus communis, Helix oculus communis J.F. Gmelin, 1791 - syn of: Pomacea glauca (C. Linnaeus, 1758) - (HELICIDAE)
- oculus planatula, Patella oculus planatula W.H. Turton - syn of: Cymbula oculus (I. von Born, 1778) - (PATELLIDAE)
- oculus schroeteri, Patella oculus schroeteri C.F.F. von Krauss - syn of: Cymbula oculus (I. von Born, 1778) - (PATELLIDAE)
- oculuscati, Patella oculuscati J. Noodt, 1819 - syn of: Scutellastra granularis (C. Linnaeus, 1758) - (PATELLIDAE)
- oculuscommunis, Helix oculuscommunis J.F. Gmelin, 1791 - syn of: Pomacea glauca (C. Linnaeus, 1758) - (HELICIDAE)
- oculushirci, Patella oculushirci E.M. Da Costa, 1771 - syn of: Cymbula oculus (I. von Born, 1778) - (PATELLIDAE)
- Ocythoe, Genus Ocythoe C.S. Rafinesque, 1814 (OCYTHOIDAE)
- OCYTHOIDAE Gray, 1849 - Family (CEPHALOPODA-COLEOIDEA [Subclass]-OCTOPODIFORMES [Superorder]-OCTOPODA [Order]-INCIRRATA [Suborder]-ARGONAUTOIDEA [Superfamily])
- odarsensis, Cernuella odarsensis P. Fagot, 1883 - syn of: Cernuella virgata (E.M. Da Costa, 1778) - (HYGROMIIDAE)
- Odatelia, syn of: Genus Hemistena C.S. Rafinesque, 1820 (UNIONIDAE)
- oddsensis, Titanosarcolites oddsensis L.W. Stephenson † - (ANTILLOCAPRINIDAE) (FOSSIL)
- odeca, Hygromia odeca (J.R. Bourguignat, 1882) - (HYGROMIIDAE)
- odenensis, Cernuella odenensis J.M. Salvañá, 1887 - syn of: Cernuella virgata (E.M. Da Costa, 1778) - (HYGROMIIDAE)
- odengensis, Batillaria odengensis (K. Martin, 1899 †) - (BATILLARIIDAE) (FOSSIL)
- odengensis, Lampania odengensis K. Martin, 1899 † - syn of: Batillaria odengensis (K. Martin, 1899 †) - (BATILLARIIDAE) (FOSSIL)
- odengensis, Lithoconus odengensis K. Martin, 1895 † - (CONIDAE) (FOSSIL)
- odengensis avaensis, Lithoconus odengensis avaensis Noetling, 1901 † - (CONIDAE) (FOSSIL)
- odengensis birmanica, Lithoconus odengensis birmanica E.W. Vredenburg, 1921 † - (CONIDAE) (FOSSIL)
- odenvillense, Protocycloceras odenvillense Ulrich & al., 1944 † - (PROTOCYCLOCERATIDAE) (FOSSIL)
- odenvillense, Buttsoceras odenvillense Ulrich & al., 1944 † - (TROEDSSONELLIDAE) (FOSSIL)
- odenvillensis, Teiichispira odenvillensis (Butts, 1926 †) - (MACLURITIDAE) (FOSSIL)
- oderi, Aphetoceras oderi Ulrich & al., 1942 † - (ESTONIOCERATIDAE) (FOSSIL)
- Oderoceras, Genus Oderoceras Ulrich & al. 1943 (PROTEROCAMEROCERATIDAE) (FOSSIL)
- Odessites, Genus Odessites Lyashenko, 1969 † (ROSSIITIDAE) (FOSSIL)
- Odetta, Subgenus Menestho (Odetta) L. de Folin, 1870 (PYRAMIDELLIDAE)
- Odhnerella, Genus Odhnerella Modell, 1964 (UNIONIDAE)
- odhneri, Mendax trizonalis odhneri (A.W.B. Powell, 1927) - (CERITHIOPSIDAE)
- odhneri, Chaetoderma odhneri (H.A. Stork, 1941) - (CHAETODERMATIDAE)
- odhneri, Glossodoris odhneri J.J. Risbec, 1953 - syn of: Hypselodoris tryoni (A. Garrett, 1873) - (CHROMODORIDIDAE)
- odhneri, Chromodoris odhneri J.J. Risbec, 1953 - syn of: Hypselodoris tryoni (A. Garrett, 1873) - (CHROMODORIDIDAE)
- odhneri, Risbecia odhneri J.J. Risbec, 1953 - syn of: Hypselodoris tryoni (A. Garrett, 1873) - (CHROMODORIDIDAE)
- odhneri, Crassatella odhneri J.R. le B. Tomlin, 1930 - syn of: Crassatella capensis (É. Lamy, 1917) - (CRASSATELLIDAE)
- odhneri, Crassatina odhneri J.R. le B. Tomlin, 1930 - syn of: Crassatella capensis (É. Lamy, 1917) - (CRASSATELLIDAE)
- odhneri, Vanuxemia odhneri Isberg, 1934 † - (CYRTODONTIDAE) (FOSSIL)
- odhneri, Doris odhneri (F.M. MacFarland, 1966) - (DORIDIDAE)
- odhneri, Archidoris odhneri F.M. MacFarland, 1966 - syn of: Doris odhneri (F.M. MacFarland, 1966) - (DORIDIDAE)
- odhneri, Eubranchus odhneri (K.M. Derjugin & E.F. Gurjanova, 1926) - (EUBRANCHIDAE)
- odhneri, Amphorina odhneri (K.M. Derjugin & E.F. Gurjanova, 1926) - syn of: Eubranchus odhneri (K.M. Derjugin & E.F. Gurjanova, 1926) - (EUBRANCHIDAE)
- odhneri, Dicata odhneri R.L. Schmekel, 1967 - (FACELINIDAE)
- odhneri, Cuthona odhneri Er. Marcus, 1959 - (FIONIDAE)
- odhneri, Gastropteron odhneri T.M. Gosliner, 1989 - (GASTROPTERIDAE)
- odhneri, Tucetona odhneri T. Iredale, 1939 - (GLYCYMERIDIDAE)
- odhneri, Leptochiton odhneri (J.R.M. Bergenhayn, 1931) - (LEPTOCHITONIDAE)
- odhneri, Liracraea odhneri A.W.B. Powell, 1942 - (MANGELIIDAE)
- odhneri, Bela odhneri Harmer † - (MANGELIIDAE) (FOSSIL)
- odhneri, Amauropsis odhneri Harmer † - (NATICIDAE) (FOSSIL)
- odhneri, Specula odhneri A.W.B. Powell, 1927 - (NEWTONIELLIDAE)
- odhneri, Parhedyle odhneri (Er. Marcus & Ev. Marcus, 1955) - (PARHEDYLIDAE)
- odhneri, Polycera odhneri Er. Marcus, 1955 - (POLYCERIDAE)
- odhneri, Inquisitor odhneri F.E. Wells, 1994 - (PSEUDOMELATOMIDAE)
- odhneri, Bankia odhneri G.F. Roch, 1931 - syn of: Bankia martensi (W. Stempell, 1899) - (TEREDINIDAE)
- odhneri, Trimusculus odhneri (B. Hubendick, 1946) - (TRIMUSCULIDAE)
- odhneri, Tritonia odhneri Er. Marcus, 1959 - (TRITONIIDAE)
- odhneri, Tritonia odhneri (J.P. Tardy, 1963) - syn of: Tritonia nilsodhneri Ev. Marcus, 1983 - (TRITONIIDAE)
- odhneri, Zeradina odhneri A.W.B. Powell, 1927 - (VANIKORIDAE)
- odhneri benthicola, Liracraea odhneri benthicola R.K. Dell, 1956 - (MANGELIIDAE)
- odhneriana, Gulella odhneriana C. Dupuis, 1923 - (STREPTAXIDAE)
- Odhneripisidium, syn of: Genus Pisidium L. Pfeiffer, 1821 (SPHAERIIDAE)
- odiensis, Zelandites odiensis (Kossmat 1895 †) - (GAUDRYCERATIDAE) (FOSSIL)
- odietei, Costigulella odietei O.C. Oke, 2013 - (STREPTAXIDAE)
- odilia, Papuina odilia W.S.S. Van Benthem-Jutting, 1965 - (CAMAENIDAE)
- odiosus, Versutaxis odiosus (H.A. Pilsbry, 1899) - (SPIRAXIDAE)
- odisseyi, Abyssotrophon odisseyi (A.N. Golikov & B.I. Sirenko, 1992) - (MURICIDAE)
- odites, Bostrycapulus odites R. Collin, 2005 - (CALYPTRAEIDAE)
- odlingi, Pinna odlingi Arkell, 1931 † - (PINNIDAE) (FOSSIL)
- Odoardia, Genus Odoardia Conti, Monari & Pallini, 1986 † (ARCHAEOGASTROPODA (UNASSIGNED)) (FOSSIL)
- odochiensis, Clisocolus odochiensis Tashiro & Kozai, 1982 † - (MACTROMYIDAE) (FOSSIL)
- Odomphium, syn of: Genus Mesodon C.S. Rafinesque in A.E.J. Férussac, 1821 (POLYGYRIDAE)
- Odoncineta, syn of: Genus Thracia W.E. Leach in H.M.D. De Blainville, 1824 (THRACIIDAE)
- odonnelli, Watinoceras odonnelli Cobban, Hook & J. Kennedy, 1989 † - (ACANTHOCERATIDAE) (FOSSIL)
- odonoghuei, Doris odonoghuei J.E. Steinberg, 1963 - (DORIDIDAE)
- odonta, Tricula odonta Y.Y. Liu, W.Z. Zhang & Y.X. Wang, 1983 - (POMATIOPSIDAE)
- Odontalus, syn of: Genus Azeca W.E. Leach in J. Fleming, 1828 (COCHLICOPIDAE)
- Odontartemon, Genus Odontartemon L. Pfeiffer, 1856 (STREPTAXIDAE)
- odontella, Gemmula odontella (F.E. Edwards, 1861 †) - (TURRIDAE) (FOSSIL)
- Odonteuxina, Subgenus Euxinastra (Odonteuxina) H. Nordsieck, 1975 (CLAUSILIIDAE)
- Odontidium, syn of: Genus Caecum J. Fleming, 1813 (CAECIDAE)
- odontina, Stylodonta odontina P.M.A. Morelet - (ACAVIDAE)
- Odontina, syn of: Genus Caecum J. Fleming, 1813 (CAECIDAE)
- odontina, Erepta odontina P.M.A. Morelet, 1851 - (HELICARIONIDAE)
- odontis, Chlorodiloma odontis (W. Wood, 1828) - (TROCHIDAE)
- Odontis, syn of: Genus Monodonta J.B.P.A. Lamarck, 1799 (TROCHIDAE)
- Odontobasis, Genus Odontobasis Meek , 1876 † (BUCCINIDAE) (FOSSIL)
- Odontobelus, Subgenus Acrocoelites (Odontobelus) Naef, 1922 † (MEGATEUTHIDIDAE) (FOSSIL)
- odontochila, Hemiphaedusa odontochila P.B. Schmacker & O. Böttger, 1891 - (CLAUSILIIDAE)
- odontochila clava, Hemiphaedusa odontochila clava C.K. Chang & T. Okubo, 1994 - (CLAUSILIIDAE)
- odontochila fulvicollis, Hemiphaedusa odontochila fulvicollis P. Ehrmann, 1954 - (CLAUSILIIDAE)
- odontochila nigra, Hemiphaedusa odontochila nigra H.A. Pilsbry, 1901 - (CLAUSILIIDAE)
- Odontocyclas, Genus Odontocyclas F. Schlüter, 1838 (CHONDRINIDAE)
- Odontocymbiola, Genus Odontocymbiola W.J. Clench & H. Turner, 1964 (VOLUTIDAE)
- Odontodineta, syn of: Genus Thracia W.E. Leach in H.M.D. De Blainville, 1824 (THRACIIDAE)
- Odontodiscoceras, Genus Odontodiscoceras Spath, 1924 † (AMMONOIDEA (UNASSIGNED)) (FOSSIL)
- Odontofusus, Genus Odontofusus Whitfield, 1892 † (FASCIOLARIIDAE) (FOSSIL)
- Odontogena, Genus Odontogena E. Cowan, 1964 (KELLIIDAE)
- Odontoglaja, Genus Odontoglaja W.B. Rudman, 1978 (AGLAJIDAE)
- Odontogryphaea, Genus Odontogryphaea Ihering, 1903 † (OSTREIDAE) (FOSSIL)
- Odontohydrobia, Genus Odontohydrobia Pavlovic, 1927 † (HYDROBIIDAE) (FOSSIL)
- odontoidea, Melanella odontoidea (A. Adams, 1861) - (EULIMIDAE)
- Odontolkites, Genus Odontolkites Buckman, 1925 † (MOLLUSCA INCERTAE SEDIS) (FOSSIL)
- Odontomaria, Genus Odontomaria Roemer , 1876 † (GOSSELETINIDAE) (FOSSIL)
- Odontomphalium, syn of: Genus Mesodon C.S. Rafinesque in A.E.J. Férussac, 1821 (POLYGYRIDAE)
- odontophora, Corilla odontophora (W.H. Benson, 1865) - (CORILLIDAE)
- odontoplax, Prionoloplax odontoplax H.A. Pilsbry, 1953 - (EPIROBIIDAE)
- Odontopolys, Genus Odontopolys Gabb, 1860 † (MURICIDAE) (FOSSIL)
- Odontopurpura, Genus Odontopurpura Vermeij & Vokes, 1997 † (NEOGASTROPODA (UNASSIGNED)) (FOSSIL)
- Odontosagda, Genus Odontosagda E.C. Von Martens, 1860 (SAGDIDAE)
- odontostoma, Bulimus odontostoma G.B. I Sowerby, 1824 - syn of: Odontostomus gargantua (A.E.J. Férussac, 1821) - (BULIMULIDAE)
- Odontostoma, syn of: Genus Odontostomus H.H. Beck, 1837 (ODONTOSTOMIDAE)
- Odontostoma, syn of: Genus Odostomia J. Fleming, 1813 (PYRAMIDELLIDAE)
- odontostoma, Truncatellina odontostoma C.A. Westerlund, 1875 - syn of: Truncatellina cylindrica (A.E.J. Férussac, 1807) - (VERTIGINIDAE)
- Odontostomia, syn of: Genus Odostomia J. Fleming, 1813 (PYRAMIDELLIDAE)
- ODONTOSTOMIDAE Pilsbry & Vanatta, 1898 - Family (GASTROPODA-HETEROBRANCHIA [Subclass]-PULMONATA [Infraclass]-STYLOMMATOPHORA [Order]-ORTHALICOIDEA [Superfamily])
- Odontostomiella, syn of: Genus Odostomella M.E.J. Bucquoy, P. Dautzenberg & G.F. Dollfus, 1883 (PYRAMIDELLIDAE)
- Odontostomus, Genus Odontostomus H.H. Beck, 1837 (ODONTOSTOMIDAE)
- odontostomus, Odontostomus odontostomus (G.B. I Sowerby, 1824) - (ODONTOSTOMIDAE)
- odontota, Plastomiltha odontota W.P. Woodring, 1982 † - (LUCINIDAE) (FOSSIL)
- odontotis, Lepidolucina odontotis (A.E. Salisbury, 1934) - (LUCINIDAE)
- Odontotrema, Genus Odontotrema W.A. Lindholm, 1927 (HYGROMIIDAE)
- Odontotrochus, Genus Odontotrochus P. Fischer in L.C. Kiener & P. Fischer, 1880 (TROCHIDAE)
- Odontotropis, syn of: Subgenus Mesodon (Patera) J.A. Albers, 1850 (POLYGYRIDAE)
- Odontoturbo, Subgenus Chilodonta (Odontoturbo) de Loriol, 1887 † (CHILODONTIDAE) (FOSSIL)
- Odontrotrochus, syn of: Genus Odontotrochus P. Fischer in L.C. Kiener & P. Fischer, 1880 (TROCHIDAE)
- Odontura, syn of: Genus Lysinoe H. Adams & A. Adams, 1855 (XANTHONYCHIDAE)
- odophora, Laeocathaica odophora O.F. von Möllendorff, 1899 - (BRADYBAENIDAE)
- odopoia, Terebra odopoia J. Gardner, 1937 † - (TEREBRIDAE) (FOSSIL)
- odorata, Aplysia odorata J.J. Risbec, 1928 - syn of: Aplysia dactylomela P.C.A.S.L. Rang, 1828 - (APLYSIIDAE)
- odorata, Sonorella odorata H.A. Pilsbry & J.H. Ferriss, 1919 - (HELMINTHOGLYPTIDAE)
- odorata marmoris, Sonorella odorata marmoris H.A. Pilsbry & J.H. Ferriss, 1919 - (HELMINTHOGLYPTIDAE)
- odoricyi, Bullata odoricyi (M. Bernardi, 1852) - (MARGINELLIDAE)
- Odostomella, Genus Odostomella M.E.J. Bucquoy, P. Dautzenberg & G.F. Dollfus, 1883 (PYRAMIDELLIDAE)
- odostomella, Odostomia odostomella A. Peñas & E. Rolán, 1999 - (PYRAMIDELLIDAE)
- Odostomia, Genus Odostomia J. Fleming, 1813 (PYRAMIDELLIDAE)
- Odostomidea, Genus Odostomidea Pilsbry & Johnson, 1917 † (OPISTHOBRANCHIA (UNASSIGNED)) (FOSSIL)
- Odostomiopsis, syn of: Genus Toledonia W.H. Dall, 1902 (DIAPHANIDAE)
- odostomoides, Siogamaia odostomoides S. Nomura, 1937 - (PYRAMIDELLIDAE)
- Odotropis, syn of: Subgenus Mesodon (Patera) J.A. Albers, 1850 (POLYGYRIDAE)
- odovychenae, Mangelia odovychenae Scarponi & al., 2016 † - (MANGELIIDAE) (FOSSIL)
- odysseus, Albinaria contaminata odysseus (O. Böttger, 1878) - (CLAUSILIIDAE)
- odysseus, Collotites odysseus Jeannet, 1951 † - (REINECKEIIDAE) (FOSSIL)
- odysseyi, Notoplax odysseyi Sirenko & Saito, 2017 - (ACANTHOCHITONIDAE)
- oebergi, Arctoceras oebergi (Mojsisovics, 1886 †) - (ARCTOCERATIDAE) (FOSSIL)
- oebergi, Dinarites oebergi Mojsisovics, 1882 † - syn of: Arctoceras blomstrandi (Lindström, 1865 †) - (SIBIRITIDAE) (FOSSIL)
- oecali, Monacha oecali B. Hausdorf & B. Páll-Gergely, 2009 - (HYGROMIIDAE)
- oeciscus, Longiverena oeciscus W.P. Woodring, 1959 † - (THIARIDAE) (FOSSIL)
- OECOPTYCHIIDAE Arkell, 1957 † - Family (CEPHALOPODA-AMMONOIDEA [Subclass]-AMMONITIDA [Order]-STEPHANOCERATOIDEA [Superfamily]) (FOSSIL)
- Oecoptychius, Genus Oecoptychius Neumayr, 1878 † (OECOPTYCHIIDAE) (FOSSIL)
- Oecoptychoceras, Genus Oecoptychoceras Buckman, 1920 † (MOLLUSCA INCERTAE SEDIS) (FOSSIL)
- Oecotraustes, Genus Oecotraustes Waagen, 1869 † (OPPELIIDAE) (FOSSIL)
- oecsensis, Gyraulus oecsensis W.A. Wenz, 1919 - (PLANORBIDAE)
- oecsensis, Vertigo oecsensis (Halaváts, 1903) † - (VERTIGINIDAE) (FOSSIL)
- Oedalia, syn of: Genus Cooperella P.P. Carpenter, 1864 (VENERIDAE)
- Oedalina, syn of: Genus Cooperella P.P. Carpenter, 1864 (VENERIDAE)
- Oedania, syn of: Genus Graphoceras Buckman, 1902 † (GRAPHOCERATIDAE) (FOSSIL)
- oedeatum, Buccinum oedeatum W.H. Dall, 1907 - syn of: Buccinum oedematum W.H. Dall, 1907 - (BUCCINIDAE)
- oedemata, Atys oedemata W.H. Dall, 1895 † - (HAMINOEIDAE) (FOSSIL)
- oedematum, Buccinum oedematum W.H. Dall, 1907 - (BUCCINIDAE)
- Oedichilus, syn of: Genus Pseudonapaeus C.A. Westerlund, 1887 (ENIDAE)
- oedigyra, Achatina oedigyra J.C. Melvill & J.H. Ponsonby, 1894 - (ACHATINIDAE)
- oedipus, Ephippodonta oedipus B.S. Morton, 1976 - (GALEOMMATIDAE)
- oedobasis, Geotrochus oedobasis J.J. Vermeulen, T.S. Liew & M. Schilthuizen, 2015 - (HELICARIONIDAE)
- oedogaster, Diplommatina oedogaster J.J. Vermeulen, 1993 - (DIPLOMMATINIDAE)
- oedogyra, Platyla oedogyra A. Paladilhe, 1868 - syn of: Platyla polita (J.D.W. Hartmann, 1840) - (ACICULIDAE)
- oedogyra, Acme oedogyra A. Paladilhe, 1868 - syn of: Platyla polita (J.D.W. Hartmann, 1840) - (HYDROBIIDAE)
- Oedomyophorus, Genus Oedomyophorus Skelton, 2004 † (CAPRINULOIDEIDAE) (FOSSIL)
- oedumi, Bittium oedumi Schnetler, 2001 † - (CERITHIIDAE) (FOSSIL)
- oegensis, Murchisonia oegensis Heidelberger & Koch, 2005 † - (MURCHISONIIDAE) (FOSSIL)
- oegir, Euaspidoceras oegir (Oppel, 1863 †) - (ASPIDOCERATIDAE) (FOSSIL)
- oehana, Rhytimya oehana Ulrich, 1893 † - (PHOLADOMYIDAE) (FOSSIL)
- oehlerti, Discomiltha oehlerti Bigot MS in Chavan 1952 † - (CARDIIDA (UNASSIGNED)) (FOSSIL)
- oehlerti, Conocardium oehlerti Barrois, 1889 † - (CONOCARDIIDAE) (FOSSIL)
- oehlerti, Palaeoneilo oehlerti Beushausen, 1895 † - syn of: Palaeoneilo beushauseni Kegel, 1913 † - (MALLETIIDAE) (FOSSIL)
- oehlerti, Leptorima oehlerti (J. Perner, 1903 †) - (MURCHISONIIDAE) (FOSSIL)
- oehlerti, Murchisonia oehlerti Blodgett & al., 1999 † - (MURCHISONIIDAE) (FOSSIL)
- oehlerti, Coelocaulus oehlerti Ulrich & Scofield, 1897 † - (MURCHISONIIDAE) (FOSSIL)
- oehlerti, Orthoceras oehlerti C. Gemmellaro, 1889 † - (ORTHOCERATIDAE) (FOSSIL)
- oehlerti, Platyceras oehlerti Spitz, 1907 † - (PLATYCERATIDAE) (FOSSIL)
- oehlerti, Subpulchellia oehlerti (M. Nicklés, 1894 †) - (PULCHELLIIDAE) (FOSSIL)
- oehlerti, Trigonia oehlerti Bigot, 1893 † - (TRIGONIIDAE) (FOSSIL)
- oehlerti, Peelerophon oehlerti (Bergeron, 1889 †) - (TROPIDODISCIDAE) (FOSSIL)
- oehlerti, Mariella oehlerti (Pervinquiere, 1910 †) - (TURRILITIDAE) (FOSSIL)
- Oehlertia, syn of: Genus Quadricarina Blodgett & Johnson, 1992 † (PORCELLIIDAE) (FOSSIL)
- oehlertiana, Ringicula oehlertiana P.M.A. Morelet, 1880 - syn of: Ringiculina doliaris (A.A. Gould, 1860) - (RINGICULIDAE)
- oelandense, Richardsonoceroides oelandense Kröger & al., 2009 † - (ONCOCERATIDAE) (FOSSIL)
- oelandense, Phtanoncoceras oelandense J. Evans & King, 1990 † - (PHTHANONCOCERATIDAE) (FOSSIL)
- oelandensis, Babinka oelandensis T. Soot-Ryen, 1969 † - (BABINKIDAE) (FOSSIL)
- Oelandia, Genus Oelandia Westergård , 1936 † (HELCIONELLIDAE) (FOSSIL)
- oelandica, Bucania oelandica E.F.R.K. Koken, 1896 † - (BUCANIIDAE) (FOSSIL)
- oelandica, Segmentina oelandica (C.A. Westerlund, 1885) - (PLANORBIDAE)
- Oelandiella, Genus Oelandiella Vostokova , 1962 † (HELCIONELLIDAE) (FOSSIL)
- Oelandoceras, Genus Oelandoceras Foerste, 1932 † (ELLESMEROCERATIDAE) (FOSSIL)
- oenea, Polititapes aureus oenea (W. Turton, 1819) - (VENERIDAE)
- oenoa, Glyphostoma oenoa P. Bartsch, 1934 - (CLATHURELLIDAE)
- oenoa, Kurtziella oenoa W.H. Dall, 1919 - syn of: Kurtziella plumbea (R.B. Hinds, 1843) - (MANGELIIDAE)
- oenoa, Lioglyphostoma oenoa (P. Bartsch, 1934) - (PSEUDOMELATOMIDAE)
- oenoa, Turbonilla oenoa P. Bartsch, 1924 - (PYRAMIDELLIDAE)
- Oenone, syn of: Genus Partula A.E.J. Férussac, 1821 (PARTULIDAE)
- oenonensis, Pusillina oenonensis (Š. Brusina, 1866) - (RISSOIDAE)
- Oenopota, Genus Oenopota O.A.L. Mörch, 1852 (MANGELIIDAE)
- Oenopotella, Genus Oenopotella A.V. Sysoev, 1988 (MANGELIIDAE)
- oenotrium, Zetoceras oenotrium (Fucini, 1901 †) - (PHYLLOCERATIDAE) (FOSSIL)
- oentoengi, Tonna oentoengi C.G. Vos, 2005 - (TONNIDAE)
- oepfingensis, Nematurella oepfingensis W.A. Wenz, 1918 † - (HYDROBIIDAE) (FOSSIL)
- Oepikila, Genus Oepikila Pojeta & Runnegar, 1976 † (RIBEIRIIDAE) (FOSSIL)
- oepybolum, Plagiostoma oepybolum (Whidborne) † - (LIMIDAE) (FOSSIL)
- oerstani, Metafruticicola oerstani B. Hausdorf, B.A. Gümüs & M.Z. Yildirim, 2004 - (HYGROMIIDAE)
- oerstedi, Columbella oerstedi E.C. Von Martens, 1897 - syn of: Anachis moesta (C.B. Adams, 1852) - (COLUMBELLIDAE)
- oerstedi, Pachychilus oerstedi O.A.L. Mörch, 1860 - (PACHYCHILIDAE)
- oerstedianum, Epitonium oerstedianum A.M. Strong & L.G. Hertlein, 1951 - syn of: Epitonium replicatum (G.B. II Sowerby, 1844) - (EPITONIIDAE)
- oerstedii, Dentalium oerstedii O.A.L. Mörch, 1861 - (DENTALIIDAE)
- oerstedii, Elysia oerstedii O.A.L. Mörch, 1859 - (PLAKOBRANCHIDAE)
- oerstedii, Solen oerstedii O.A.L. Mörch, 1860 - (SOLENIDAE)
- oerstedii numerosum, Dentalium oerstedii numerosum W.H. Dall in H.A. Pilsbry & B. Sharp, 1897 - syn of: Dentalium oerstedii O.A.L. Mörch, 1861 - (DENTALIIDAE)
- oertzeni, Deroceras oertzeni (H.R. Simroth, 1889) - (AGRIOLIMACIDAE)
- oertzeni, Albinaria olivieri oertzeni (O. Böttger, 1889) - (CLAUSILIIDAE)
- oertzeni, Helicella oertzeni (H. von Maltzan, 1887) - (HYGROMIIDAE)
- oertzeni, Zonites oertzeni E.C. Von Martens, 1889 - (ZONITIDAE)
- oeschingense, Peltoceras oeschingense Prieser, 1937 † - (ASPIDOCERATIDAE) (FOSSIL)
- oesiacus, Unio oesiacus É.A.A. Locard, 1889 - syn of: Unio pictorum (C. Linnaeus, 1758) - (UNIONIDAE)
- oesiensis, Micrancilla oesiensis J.M. Pacaud, D. Merle & Pons, 2013 † - (ANCILLARIIDAE) (FOSSIL)
- oestergreni, Enteroxenos oestergreni K.E.H. Bonnevie, 1902 - (EULIMIDAE)
- Oestophora, Genus Oestophora P. Hesse, 1907 (TRISSEXODONTIDAE)
- Oestophorella, Genus Oestophorella G.J. Pfeffer, 1929 (TRISSEXODONTIDAE)
- oestreichi, Helix oestreichi W. Kobelt, 1902 - (HELICIDAE)
- oetae, Codringtonia oetae (W. Kobelt, 1879) - (HELICIDAE)
- oetae aetolica, Codringtonia oetae aetolica (O. Böttger, 1888) - (HELICIDAE)
- oetae coracis, Codringtonia oetae coracis (W. Kobelt, 1902) - (HELICIDAE)
- oetaea, Helix oetaea E.C. Von Martens, 1889 - syn of: Josephinella argentellei (W. Kobelt, 1872) - (HELICIDAE)
- oetelshofensis, Euryzone delphinuloides oetelshofensis (Schlotheim, 1820 †) - (GOSSELETINIDAE) (FOSSIL)
- oetensis, Macedonica guicciardii oetensis (C.A. Westerlund, 1901) - (CLAUSILIIDAE)
- oettlyi, Eratoidea oettlyi J. Espinosa & J.A. Ortea, 2013 - (MARGINELLIDAE)
- oeyenhausii, Natica oeyenhausii Klipstein, 1843 † - (NATICIDAE) (FOSSIL)
- ofeliae, Hyalina ofeliae T. Cossignani, 1998 - syn of: Hyalina brocktoni (L.J. Shackleford, 1914) - (MARGINELLIDAE)
- ofellata, Candidula ofellata É.A.A. Locard, 1899 - syn of: Candidula olissipensis (G. Servain, 1880) - (HYGROMIIDAE)
- ofensis, Pontophaedusella ofensis H. Nordsieck, 1994 - (CLAUSILIIDAE)
- Offachloritis, Genus Offachloritis T. Iredale, 1933 (CAMAENIDAE)
- Offadesma, Genus Offadesma T. Iredale, 1930 (PERIPLOMATIDAE)
- offarcinatum, Acanthoceras offarcinatum White, 1887 † - (ACANTHOCERATIDAE) (FOSSIL)
- officeri, Pernagera officeri (C.M.D.E. Legrand, 1871) - (CHAROPIDAE)
- officinalis, Sepia officinalis C. Linnaeus, 1758 - (SEPIIDAE)
- officinalis hierreda, Sepia officinalis hierreda P.C.A.S.L. Rang, 1837 - syn of: Sepia hierredda P.C.A.S.L. Rang, 1837 - (SEPIIDAE)
- officinalis vermiculata, Sepia officinalis vermiculata J.R.C. Quoy & J.P. Gaimard, 1832 - (SEPIIDAE)
- offlexa, Adelphotectonica offlexa T. Iredale, 1931 - syn of: Adelphotectonica reevei (S.C.T. Hanley, 1862) - (ARCHITECTONICIDAE)
- Offleya, Genus Offleya Poulsen, 1974 † (BUCANIIDAE) (FOSSIL)
- Offleyoceras, Genus Offleyoceras Foerste, 1928 † (OFFLEYOCERATIDAE) (FOSSIL)
- OFFLEYOCERATIDAE Flower, 1962 † - Family (CEPHALOPODA-ORTHOCERATOIDEA [Subclass]-DISSIDOCERIDA [Order]) (FOSSIL)
- Offleyotrochus, Genus Offleyotrochus Peel, 1979 † (EUOMPHALIDAE) (FOSSIL)
- Offlyeotrochus, Genus Offlyeotrochus † (EUOMPHALINA (UNASSIGNED)) (FOSSIL)
- Offneria, Genus Offneria Paquier, 1905 † (CAPRINIDAE) (FOSSIL)
- offsetensis, Callitrigonia offsetensis Kelly 1995 † - (TRIGONIIDAE) (FOSSIL)
- offtonensis, Columella offtonensis R. Sheppard, 1823 - syn of: Columella edentula (J.P.R. Draparnaud, 1805) - (VERTIGINIDAE)
- ofuensis, Asperitas cidaris ofuensis B. Rensch, 1931 - (DYAKIIDAE)
- ofuensis, Mastoniaeforis ofuensis (F. Baker & V.D.P. Spicer, 1935) - (TRIPHORIDAE)
- ogachiensis, Palaeoneilo ogachiensis I. Hayasaka, 1924 † - (MALLETIIDAE) (FOSSIL)
- ogaitoi, Cyclotus ogaitoi H. Minato, 1988 - (CYCLOPHORIDAE)
- ogaitoi, Amaea ogaitoi H. Masahito & T. Habe, 1975 - (EPITONIIDAE)
- Ogaridiscus, syn of: Genus Pristiloma C.M.F. Ancey, 1887 (PRISTILOMATIDAE)
- ogasaensis, Oscilla ogasaensis (S. Nomura, 1939) - (PYRAMIDELLIDAE)
- ogasawarae, Boninena ogasawarae (H.A. Pilsbry, 1901) - (ENIDAE)
- ogasawarae, Boninosuccinea ogasawarae (H.A. Pilsbry, 1901) - (SUCCINEIDAE)
- ogasawaraensis, Lima ogasawaraensis T. Habe, 1993 - (LIMIDAE)
- ogasawarai, Keenocardium ogasawarai A.I. Kafanov, 2000 † - syn of: Clinocardium asagaiense (J. Makiyama, 1934 †) - (CARDIIDAE) (FOSSIL)
- ogasawarai, Portlandella ogasawarai (S. Uozumi, 1957 †) - (NUCULANIDAE) (FOSSIL)
- ogasawarana, Lamellidea ogasawarana H.A. Pilsbry & C.M. Cooke, 1915 - (ACHATINELLIDAE)
- ogasawarana, Kaliella ogasawarana H.A. Pilsbry, 1902 - (CHRONIDAE)
- ogasawarana, Mitrella ogasawarana H.A. Pilsbry, 1904 - syn of: Graphicomassa margarita (L.A. Reeve, 1859) - (COLUMBELLIDAE)
- ogasawarana, Columbella ogasawarana H.A. Pilsbry, 1904 - syn of: Graphicomassa margarita (L.A. Reeve, 1859) - (COLUMBELLIDAE)
- ogasawarana, Thala ogasawarana H.A. Pilsbry, 1904 - (COSTELLARIIDAE)
- ogasawarana, Melanella ogasawarana (H.A. Pilsbry, 1905) - (EULIMIDAE)
- ogasawarana, Gastrocopta ogasawarana H.A. Pilsbry, 1916 - (GASTROCOPTIDAE)
- ogasawarana, Helicarion ogasawarana H.A. Pilsbry, 1902 - (HELICARIONIDAE)
- Ogasawarana, Genus Ogasawarana A. Wagner, 1905 (HELICINIDAE)
- ogasawarana, Ogasawarana ogasawarana (H.A. Pilsbry, 1902) - (HELICINIDAE)
- ogasawarana, Oenopota ogasawarana T.A. Okutani, K. Fujikura & T. Sasaki, 1993 - (MANGELIIDAE)
- ogasawarana, Alvania ogasawarana (H.A. Pilsbry, 1904) - (RISSOIDAE)
- ogasawarana, Succinea ogasawarana H.A. Pilsbry & C.M. Cooke, 1915 - (SUCCINEIDAE)
- ogasawarana, Lunella ogasawarana T. Nakano, Takashashi & T. Ozawa, 2007 - (TURBINIDAE)
- ogasawarana, Lyria ogasawarana P. Bail & M. Chino, 2015 - (VOLUTIDAE)
- ogasawarana longa, Lamellidea ogasawarana longa H.A. Pilsbry, 1915 - (ACHATINELLIDAE)
- ogasawarazimana, Milda ogasawarazimana (S. Nomura, 1939) - (PYRAMIDELLIDAE)
- ogasawarazimana, Pyramidella ogasawarazimana S. Nomura, 1939 - syn of: Milda ogasawarazimana (S. Nomura, 1939) - (PYRAMIDELLIDAE)
- ogasawarensis, Erosaria cernica ogasawarensis F.A. Schilder, 1944 - (CYPRAEIDAE)
- ogatsuense, Domatoceras ogatsuense Ehiro & Takizawa, 1989 † - (GRYPOCERATIDAE) (FOSSIL)
- ogawai, Anadara ogawai J. Makiyama, 1943 † - (ARCIDAE) (FOSSIL)
- ogawai, Ptilotrigonia ogawai (Yehara 1923) † - (PTEROTRIGONIIDAE) (FOSSIL)
- ogbei, Cimomia ogbei O.S. Adegoke, 1977 † - (HERCOGLOSSIDAE) (FOSSIL)
- ogbei, Cypraedia ogbei O.S. Adegoke, 1977 † - (OVULIDAE) (FOSSIL)
- ogbeifuni, Costigulella ogbeifuni O.C. Oke, 2013 - (STREPTAXIDAE)
- Ogeramua, Genus Ogeramua Christensen, 2017 (CAMAENIDAE)
- ogeramuensis, Papuanella ogeramuensis (W. Kobelt, 1914) - (CAMAENIDAE)
- ogerieni, Ammonites ogerieni Dumortier, 1874 † - syn of: Haugia jugosa (J. de C. Sowerby, 1815 †) - (AMMONITIDA (unassigned)) (FOSSIL)
- ogerieni, Melanopsis ogerieni É.A.A. Locard, 1883 † - (MELANOPSIDAE) (FOSSIL)
- ogerieni, Haugia ogerieni Sowerby, 1815 † - syn of: Haugia jugosa (J. de C. Sowerby, 1815 †) - (PHYMATOCERATIDAE) (FOSSIL)
- ogiaca, Cernuella ogiaca G. Servain in É.A.A. Locard, 1882 - syn of: Cernuella virgata (E.M. Da Costa, 1778) - (HYGROMIIDAE)
- ogiavle, Prionodoceras ogiavle S.S. Buckman, 1923 † - (CARDIOCERATIDAE) (FOSSIL)
- ogilviae, Calliostoma ogilviae E.A.L. Kittl, 1894 † - (CALLIOSTOMATIDAE) (FOSSIL)
- ogilviae, Hologyra ogilviae Böhm, 1895 † - (NATICOPSIDAE) (FOSSIL)
- ogilviana, Caricella ogilviana C.J. Maury, 1912 † - (VOLUTIDAE) (FOSSIL)
- ogilviei, Cophinoceras ogilviei Whitehouse, 1928 † - (DESMOCERATIDAE) (FOSSIL)
- Ogivia, Subgenus Triphora (Ogivia) G.F. Harris & H.W. Burrows, 1891 † (TRIPHORIDAE) (FOSSIL)
- oglanlensis, Deshayesites oglanlensis T.N. Bogdanova, 1979 † - (DESHAYESITIDAE) (FOSSIL)
- oglasae, Ciliellopsis oglasae F.L. Giusti & G. Manganelli, 1990 - (HYGROMIIDAE)
- oglasicola, Alzonula oglasicola F.L. Giusti, 1968 - (OXYCHILIDAE)
- oglei, Chersaecia oglei (H.H. Godwin-Austen, 1879) - (PLECTOPYLIDAE)
- ogmoraphe, Pyrgulopsis ogmoraphe T.E. Thompson, 1977 - syn of: Marstonia ogmorhaphe T.E. Thompson, 1977 - (HYDROBIIDAE)
- ogmorhaphe, Marstonia ogmorhaphe T.E. Thompson, 1977 - (HYDROBIIDAE)
- ogmorphaphe, Pyrgulopsis ogmorphaphe T.E. Thompson, 1977 - syn of: Marstonia ogmorhaphe T.E. Thompson, 1977 - (HYDROBIIDAE)
- ogonerense, Dieneroceras ogonerense Ermakova, 1974 † - syn of: Rudolftruempyiceras apostolicum (Smith, 1932 †) - (COLUMBITIDAE) (FOSSIL)
- ogonoi, Colombellina ogonoi T. Kase † - (COLOMBELLINIDAE) (FOSSIL)
- ogoouensis, Ziba ogoouensis G. Biraghi, 1984 - (MITRIDAE)
- ogormani, Pollia ogormani (A.E.M. Cossmann, 1923 †) - (BUCCINIDAE) (FOSSIL)
- ogormani, Discors ogormani A.E.M. Cossmann, 1923 † - (CARDIIDAE) (FOSSIL)
- ogormani, Turricula ogormani A.E.M. Cossmann, 1923 † - (CLAVATULIDAE) (FOSSIL)
- ogormani, Crassatella ogormani A.E.M. Cossmann † - (CRASSATELLIDAE) (FOSSIL)
- ogormani, Vicetia ogormani A.E.M. Cossmann, 1923 † - (CYPRAEIDAE) (FOSSIL)
- ogormani, Ellobium ogormani (A.E.M. Cossmann, 1923 †) - (ELLOBIIDAE) (FOSSIL)
- ogormani, Daphnellopsis ogormani (A.E.M. Cossmann †) - (MURICIDAE) (FOSSIL)
- ogormani, Poirieria flexuosa ogormani (A.E.M. Cossmann, 1923 †) - (MURICIDAE) (FOSSIL)
- ogormani, Pholadomya ogormani A.E.M. Cossmann, 1922 † - (PHOLADOMYIDAE) (FOSSIL)
- ogormani, Rimella ogormani A.E.M. Cossmann, 1923 † - syn of: Chedevillia mirabilis ogormani A.E.M. Cossmann, 1923 † - (RIMELLIDAE) (FOSSIL)
- ogormani, Chedevillia mirabilis ogormani A.E.M. Cossmann, 1923 † - (ROSTELLARIIDAE) (FOSSIL)
- ogormani, Scaphander ogormani A.E.M. Cossmann, 1923 † - (SCAPHANDRIDAE) (FOSSIL)
- ogormani, Spondylus ogormani A.E.M. Cossmann, 1922 † - (SPONDYLIDAE) (FOSSIL)
- ogormani, Callista ogormani A.E.M. Cossmann, 1923 † - (VENERIDAE) (FOSSIL)
- ogormani, Athleta ogormani (A.E.M. Cossmann, 1923 †) - (VOLUTIDAE) (FOSSIL)
- ogrodzieniecensis, Turcica ogrodzieniecensis A. Kaim, 2004 † - (CHILODONTIDAE) (FOSSIL)
- ogulineci, Shikamaia ogulineci Kochansky-Devide, 1978 † - syn of: Saikraconcha ogulineci (Kochansky-Devide, 1978 †) - (ALATOCONCHIDAE) (FOSSIL)
- ogulineci, Shikamaia ogulineci Kochansky-Devide, 1978 † - syn of: Saikraconcha ogulineci (Kochansky-Devide, 1978 †) - (ALATOCONCHIDAE) (FOSSIL)
- ogulineci, Saikraconcha ogulineci (Kochansky-Devide, 1978 †) - (SAIKRACONCHIDAE) (FOSSIL)
- ogum, Conasprella ogum (E.J. Petuch & B.W. Myers, 2014) - (CONIDAE)
- ogum, Jaspidiconus ogum E.J. Petuch & B.W. Myers, 2014 - syn of: Conasprella ogum (E.J. Petuch & B.W. Myers, 2014) - (CONIDAE)
- ogum, Pustulatirus ogum (E.J. Petuch, 1979) - (FASCIOLARIIDAE)
- ogurae, Sinanodonta ogurae (J.T. Kuroda & T. Habe, 1987) - (UNIONIDAE)
- ogurai, Acteon ogurai (Y. Otuka, 1938 †) - (ACTEONIDAE) (FOSSIL)
- ogurai, Hedecardium ogurai (Y. Otuka, 1938 †) - (CARDIIDAE) (FOSSIL)
- ogurana, Ophiodermella ogurana (M. Yokoyama, 1922 †) - (BORSONIIDAE) (FOSSIL)
- ogurana, Genotia ogurana M. Yokoyama, 1922 † - syn of: Ophiodermella ogurana (M. Yokoyama, 1922 †) - (BORSONIIDAE) (FOSSIL)
- Oguranodonta, Genus Oguranodonta J.T. Kuroda & T. Habe, 1987 (UNIONIDAE)
- ogygia, Clathrospira ogygia E.F.R.K. Koken & J. Perner, 1925 † - (EOTOMARIIDAE) (FOSSIL)
- ogygia, Septa ogygia W.P. Woodring, 1959 † - (RANELLIDAE) (FOSSIL)
- ogygiaca, Trochoidea spratti ogygiaca C.A. Westerlund, 1889 - (HYGROMIIDAE)
- ogygiae, Temnodiscus ogygiae E.F.R.K. Koken & J. Perner, 1925 † - (TROPIDODISCIDAE) (FOSSIL)
- Ogygoceras, Genus Ogygoceras Ulrich, Foerste, Miller & Unklesbay, 1944 † (ORTHOCERATIDAE) (FOSSIL)
- oharai, Gudeodiscus giardi oharai B. Páll-Gergely, 2013 - (PLECTOPYLIDAE)
- oharai, Vargapupa oharai Páll-Gergely, 2015 - (PUPINIDAE)
- ohashii, Trogloconcha ohashii T. Kase & Y. Kano, 2002 - (LAROCHEIDAE)
- ohashii, Cratis ohashii I. Hayami & T. Kase, 1993 - (PHILOBRYIDAE)
- ohashii, Microliotia ohashii T. Kase, 1998 - (PICKWORTHIIDAE)
- oheatora, Australdonta oheatora A.F. Sartori, O. Gargominy & Fontaine, 2013 - (ENDODONTIDAE)
- ohiensis, Potamilus ohiensis C.S. Rafinesque, 1820 - (UNIONIDAE)
- Ohioceras, Genus Ohioceras Shimizu & Obata, 1935 † (KIONOCERATIDAE) (FOSSIL)
- ohioense, Conocardium ohioense F.B. Meek, 1871 † - syn of: Hippocardia mundula (E.M. Fletcher, 1943 †) - (CONOCARDIIDAE) (FOSSIL)
- ohioense, Hippocardia ohioense F.B. Meek, 1871 † - (HIPPOCARDIIDAE) (FOSSIL)
- ohioense, Pleuroclymenia ohioense House, W.J. Gordon & Hlavin, 1986 † - (PLATYCLYMENIIDAE) (FOSSIL)
- ohioensis, Anthracopupa ohioensis R.P. Whitfield, 1881 † - (ANTHRACOPUPIDAE) (FOSSIL)
- ohioensis, Donaldina ohioensis K. Bandel, 2002 † - (DONALDINIDAE) (FOSSIL)
- ohioensis, Euchondria ohioensis (Mark, 1912 †) - (EUCHONDRIIDAE) (FOSSIL)
- ohioensis, Acanthopecten ohioensis Mark, 1912 † - syn of: Euchondria ohioensis (Mark, 1912 †) - (LIMIPECTINIDAE) (FOSSIL)
- ohioensis, Paracyclas ohioensis F.B. Meek † - (PARACYCLIDAE) (FOSSIL)
- ohioensis, Pernopecten ohioensis Newell, 1938 † - (PERNOPECTINIDAE) (FOSSIL)
- ohioensis, Pallifera ohioensis V. Sterki, 1908 - (PHILOMYCIDAE)
- ohioensis, Goniobasis ohioensis (I. Lea, 1852) - (PLEUROCERIDAE)
- ohioensis, Palaeoconcha ohioensis Bassler, 1915 † - (PRAENUCULIDAE) (FOSSIL)
- ohioensis, Prionoceras ohioensis (Winchell, 1870 †) - (PRIONOCERATIDAE) (FOSSIL)
- ohioensis, Bigalea ohioensis Pojeta & Runnegar, 1976 † - (PSEUDOBIGALEAIDAE) (FOSSIL)
- ohioensis, Placopterina ohioensis Hoare & al., 1978 † - (PTERINEIDAE) (FOSSIL)
- ohioensis, Potamilus ohioensis C.S. Rafinesque, 1820 - syn of: Potamilus ohiensis C.S. Rafinesque, 1820 - (UNIONIDAE)
- ohiroi, Anisocorbula ohiroi O. Masuda, 1966 † - (CORBULIDAE) (FOSSIL)
- ohiroi, Cypraea ohiroi O. Masuda, 1967 † - (CYPRAEIDAE) (FOSSIL)
- ohishii, Merisca ohishii Inoue & Mizuno 1969 † - (TELLINIDAE) (FOSSIL)
- ohlini, Trophon ohlini H. Strebel, 1904 - (MURICIDAE)
- ohlini, Pleurotomella ohlini (H. Strebel, 1905) - (RAPHITOMIDAE)
- Ohlinia, syn of: Genus Toledonia W.H. Dall, 1902 (DIAPHANIDAE)
- ohlmeri, Cathaica ohlmeri A. Andreae, 1903 - (BRADYBAENIDAE)
- ohmi, Pseudothurmannia ohmi (H. Winkler, 1868 †) - (CRIOCERATITIDAE) (FOSSIL)
- ohmurai, Coralliophila ohmurai S. Kosuge, 1985 - (MURICIDAE)
- Ohola, syn of: Genus Polycera G.L.C.F.D. Cuvier, 1817 (POLYCERIDAE)
- ohomachii, Strombina ohomachii T. Oinomikado, 1939 † - syn of: Strombina cyphonotus H.A. Pilsbry & Johnson, 1911 † - (COLUMBELLIDAE) (FOSSIL)
- ohopeana, Sigapatella ohopeana B.A. Marshall, 2003 † - (CALYPTRAEIDAE) (FOSSIL)
- ohopohoensis, Sculptaria ohopohoensis A. Zilch, 1939 - (SCULPTARIIDAE)
- ohridana, Gocea ohridana S. Hadžišce, 1956 - (HYDROBIIDAE)
- ohridana, Strugia ohridana P. Radoman, 1973 - (HYDROBIIDAE)
- Ohridohauffenia, Genus Ohridohauffenia S. Hadžišce, 1956 (HYDROBIIDAE)
- Ohridohoratia, syn of: Genus Gocea S. Hadžišce, 1956 (HYDROBIIDAE)
- Ohridopyrgula, Genus Ohridopyrgula P. Radoman, 1955 (HYDROBIIDAE)
- Ohridosturanya, Genus Ohridosturanya P. Radoman, 1973 (HYDROBIIDAE)
- Ohridotropidina, Subgenus Valvata (Ohridotropidina) S. Hadžišce 1955 (VALVATIDAE)
- Ohrigocea, Genus Ohrigocea S. Hadžišce, 1956 (HYDROBIIDAE)
- ohshimai, Peregrinamor ohshimai Shôji, 1938 - (CYAMIIDAE)
- ohshimai, Geitodoris ohshimai (K. Baba, 1936) - (DISCODORIDIDAE)
- ohshimai, Epimenia ohshimai K. Baba, 1940 - (EPIMENIIDAE)
- ohshimai, Fronsella ohshimai T. Habe, 1958 - (MONTACUTIDAE)
- ohshimai, Anisodevonia ohshimai (T. Kawahara, 1942) - (MONTACUTIDAE)
- Ohshimaia, syn of: Genus Devonia R. Winckworth, 1930 (MONTACUTIDAE)
- ohtai, Felaniella ohtai T. Kase & S. Miyauchi, 1996 - (UNGULINIDAE)
- oicium, Turrithyra semicora oicium C. de la Torre & P. Bartsch, 1941 - (POMATIIDAE)
- Oicodespina, syn of: Genus Onchidoris H.M.D. De Blainville, 1816 (ONCHIDORIDIDAE)
- oidaleus, Proplanulites oidaleus Buckman † - (PERISPHINCTIDAE) (FOSSIL)
- oineus, Parathisbites oineus McLearn, 1947 † - (PARATHISBITIDAE) (FOSSIL)
- oinouyei, Conus oinouyei Yokoyama, 1928 † - (CONIDAE) (FOSSIL)
- oioensis, Achatinella apexfulva oioensis D.A. Welch, 1942 - (ACHATINELLIDAE)
- Oiophyllites, Genus Oiophyllites Spath , 1953 † (DESMOCERATIDAE) (FOSSIL)
- oishiae, Echinophoria wyvillei oishiae (R.B. Watson, 1886) - (CASSIDAE)
- oishii, Graphiconus oishii (T. Shikama, 1977) - (CONIDAE)
- oishii, Perotrochus oishii (T. Shikama, 1973) - (PLEUROTOMARIIDAE)
- Oistoceras, Subgenus Aegoceras (Oistoceras) Spath, 1938 † (LIPAROCERATIDAE) (FOSSIL)
- Oistotrigonia, Genus Oistotrigonia Cox, 1952 † (PTEROTRIGONIIDAE) (FOSSIL)
- oitensis, Pseudocardium oitensis L. Krishtofovich, 1964 † - syn of: Pseudocardium evalensis (Ilyina, 1957 †) - (MACTRIDAE) (FOSSIL)
- Oithona, syn of: Genus Fiona J. Alder & A. Hancock, 1851 (FIONIDAE)
- Oithonella, syn of: Genus Marsenina J.E. Gray, 1850 (VELUTINIDAE)
- oiticica, Carnauba oiticica Anelli & al., 2009 † - (MEGADESMIDAE) (FOSSIL)
- ojaiensis, Pyrgulopsis ojaiensis R. Hershler, H.X. Liu & al., 2016 - (HYDROBIIDAE)
- ojianus, Alveinus ojianus (M. Yokoyama, 1927) - (KELLIELLIDAE)
- ojiensis, Amaea ojiensis (M. Yokoyama, 1927 †) - (EPITONIIDAE) (FOSSIL)
- ojinagaense, Ojinagiceras ojinagaense Cobban & J. Kennedy, 1989 † - (LYELLICERATIDAE) (FOSSIL)
- Ojinagiceras, Genus Ojinagiceras Cobban & Kennedy, 1989 † (LYELLICERATIDAE) (FOSSIL)
- okadai, Helicostyla okadai J.T. Kuroda, 1932 - (BRADYBAENIDAE)
- okadai, Stilapex okadai T. Habe, 1986 - (EULIMIDAE)
- okadai, Ringicula okadai (T. Habe, 1956) - (RINGICULIDAE)
- okadai, Ringiculina okadai T. Habe, 1956 - syn of: Ringicula okadai (T. Habe, 1956) - (RINGICULIDAE)
- okadai, Tosapecten suzukii okadai Nakazawa, 1960 † - (TOSAPECTINIDAE) (FOSSIL)
- okadai, Colpospira okadai T. Nagao - (TURRITELLIDAE)
- Okadaia, syn of: Genus Vayssierea J.J. Risbec, 1928 (OKADAIIDAE)
- OKADAIIDAE Baba, 1930 - Family (GASTROPODA-HETEROBRANCHIA [Subclass]-OPISTHOBRANCHIA [Infraclass]-NUDIBRANCHIA [Order]-POLYCEROIDEA [Superfamily])
- okadakensis, Cymbophora okadakensis Tamura, 1977 † - (MACTRIDAE) (FOSSIL)
- okaensis, Callispira okaensis Mazaev, 2003 † - (ACANTHONEMATIDAE) (FOSSIL)
- okaensis, Acroloxus okaensis N.D. Kruglov & Y.I. Starobogatov, 1991 - (ACROLOXIDAE)
- okaensis, Stegocoelia okaensis Mazaev, 2001 † - (GONIASMATIDAE) (FOSSIL)
- okaensis, Paludina okaensis S. Clessin, 1875 - syn of: Viviparus viviparus (C. Linnaeus, 1758) - (VIVIPARIDAE)
- okai, Pseudosacculus okai Y. Hirase, 1927 - syn of: Pseudosacculus okkai (Y. Hirase, 1927) - (VELUTINIDAE)
- Okaites, Subgenus Binatisphinctes (Okaites) Teisseyre, 1883 † (PERISPHINCTIDAE) (FOSSIL)
- okamkurai, Odostomia okamkurai T. Habe, 1971 - (PYRAMIDELLIDAE)
- okamotoi, Amamiconcha okamotoi T. Habe, 1962 - (CAPULIDAE)
- okamotoi, Conus okamotoi J.T. Kuroda & K. Itô, 1961 - syn of: Calamiconus lischkeanus (H.C. Weinkauff, 1875) - (CONIDAE)
- okamotoi, Limulatys okamotoi (T. Habe, 1952) - (HAMINOEIDAE)
- okamotoi, Halotapada okamotoi (T. Habe, 1962) - (PLANAXIDAE)
- okamotoi, Astralium okamotoi J.T. Kuroda & T. Habe, 1961 - (TURBINIDAE)
- okamotoi, Macromphalus okamotoi T. Habe, 1962 - (VANIKORIDAE)
- okamurai, Cipangocharax okamurai M. Azuma, 1980 - (CYCLOPHORIDAE)
- okamurai, Leptochiton okamurai H. Saito, 2001 - (LEPTOCHITONIDAE)
- okamurai, Boonea okamurai S. Hori & T.A. Okutani, 1996 - (PYRAMIDELLIDAE)
- okanoi, Euhadra sandai okanoi H.A. Pilsbry & T.D.A. Cockerell, 1927 - (BRADYBAENIDAE)
- okawai, Ancilla okawai M. Yokoyama, 1923 † - syn of: Amalda albocallosa (C.E. Lischke, 1873) - (ANCILLARIIDAE) (FOSSIL)
- okawensis, Stegocoelia okawensis Thein & Nitecki, 1974 † - (GONIASMATIDAE) (FOSSIL)
- okawensis, Salterospira okawensis Thein & Nitecki, 1974 † - (GOSSELETINIDAE) (FOSSIL)
- okawensis, Nuculavus okawensis (H.G. Schenck, 1939 †) - (NUCULIDAE) (FOSSIL)
- okayamaensis, Coneuplecta okayamaensis J.T. Kuroda, 1950 - (EUCONULIDAE)
- okayamensis, Reinia hungerfordiana okayamensis J.T. Kuroda & M. Azuma, 1982 - (CLAUSILIIDAE)
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