- opea, Patella opea L.A. Reeve, 1855 - syn of: Lottia antillarum (G.B. I Sowerby, 1834) - (PATELLIDAE)
- opeas, Strobilus opeas C.M. Cooke & Y. Kondo, 1960 - (ACHATINELLIDAE)
- opeas, Epitonium opeas R.N. Kilburn, 1985 - (EPITONIIDAE)
- opeas, Volutaxis opeas (H.B. Baker, 1939) - (SPIRAXIDAE)
- Opeas, Genus Opeas J.A. Albers, 1850 (SUBULINIDAE)
- opeas intermedius, Strobilus opeas intermedius C.M. Cooke & Y. Kondo, 1960 - (ACHATINELLIDAE)
- opeatochila, Dimorphosoma opeatochila J. Gardner, 1875 † - (APORRHAIDAE) (FOSSIL)
- Opeatostoma, Genus Opeatostoma S.S. Berry, 1958 (FASCIOLARIIDAE)
- opella, Opeas opella H.A. Pilsbry & E.G. Vanatta, 1906 - (SUBULINIDAE)
- Opella, Genus Opella H.J. Finlay, 1929 (TURBINIDAE)
- opephora, Miralda opephora J.C. Melvill, 1898 - (PYRAMIDELLIDAE)
- operanum, Opeas operanum (L. Pfeiffer, 1846) - (SUBULINIDAE)
- operanus, Bulimus operanus L. Pfeiffer, 1846 - syn of: Opeas operanum (L. Pfeiffer, 1846) - (BULIMULIDAE)
- opercularis, Leptonotis opercularis (G.P. Deshayes, 1824 †) - (HIPPONICIDAE) (FOSSIL)
- opercularis, Ostrea opercularis C. Linnaeus, 1758 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (OSTREIDAE)
- opercularis, Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis, Menetus opercularis (A.A. Gould, 1847) - (PLANORBIDAE)
- opercularis, Sanguinolaria opercularis G.B. I Sowerby, 1828 - syn of: Psammotella cruenta (J. Lightfoot, 1786) - (PSAMMOBIIDAE)
- opercularis, Tellina opercularis G.B. I Sowerby, 1828 - syn of: Psammotella cruenta (J. Lightfoot, 1786) - (TELLINIDAE)
- opercularis albopurpurascens, Pecten opercularis albopurpurascens J.B.P.A. Lamarck, 1819 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis albovariegata, Pecten opercularis albovariegata A. Clement, 1875 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis aspera, Pecten opercularis aspera M.E.J. Bucquoy, P. Dautzenberg & G.F. Dollfus, 1889 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis audouinii, Aequipecten opercularis audouinii (B.C.M. Payraudeau, 1826) - (PECTINIDAE)
- opercularis concolor, Pecten opercularis concolor M.E.J. Bucquoy, P. Dautzenberg & G.F. Dollfus, 1889 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis depressa, Pecten opercularis depressa É.A.A. Locard, 1888 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis elongata, Pecten opercularis elongata J.G. Jeffreys, 1864 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis lineata, Aequipecten opercularis lineata (E.M. Da Costa, 1778) - (PECTINIDAE)
- opercularis luteus, Pecten opercularis luteus J.B.P.A. Lamarck, 1819 - syn of: Aequipecten opercularis (C. Linnaeus, 1758) - (PECTINIDAE)
- opercularis mauritiana, Aequipecten opercularis mauritiana (C. Linnaeus, 1758) - (PECTINIDAE)
- operculata, Corbula operculata R.A. Philippi, 1848 - (CORBULIDAE)
- operculata, Cryptonatica operculata (J.G. Jeffreys, 1885) - (NATICIDAE)
- operculata, Natica operculata F. Nordsieck, 1973 - syn of: Notocochlis dillwynii (B.C.M. Payraudeau, 1826) - (NATICIDAE)
- operculata, Peltospira operculata J.H. McLean, 1989 - (PELTOSPIRIDAE)
- operculata, Sanguinolaria operculata J.F. Gmelin, 1791 - syn of: Psammotella cruenta (J. Lightfoot, 1786) - (PSAMMOBIIDAE)
- operculata, Retusa operculata Y.S. Minichev, 1966 - (RETUSIDAE)
- operculata, Tellina operculata J.F. Gmelin, 1791 - syn of: Psammotella cruenta (J. Lightfoot, 1786) - (TELLINIDAE)
- operculata farolita, Tectonatica operculata farolita F. Nordsieck, 1973 - syn of: Notocochlis dillwynii (B.C.M. Payraudeau, 1826) - (NATICIDAE)
- Operculatum, syn of: Genus Umbraculum H.C.F. Schumacher, 1817 (UMBRACULIDAE)
- Operculella, Genus Operculella Monterosato, 1915 (ANOMIIDAE) (FOSSIL)
- Operculella, syn of: Genus Anomia C. Linnaeus, 1758 (ANOMIIDAE)
- operculiformis, Argopecten operculiformis F. Toula, 1909 † - (PECTINIDAE) (FOSSIL)
- operculina, Hirasea operculina (A.A. Gould, 1859) - (ENDODONTIDAE)
- operculum, Varicorbula operculum (R.A. Philippi, 1848 †) - (CORBULIDAE) (FOSSIL)
- operculus, Halkieria operculus (Z.X. Qian, 1984 †) - (HALKIERIIDAE) (FOSSIL)
- operculus, Sachites operculus Z.X. Qian, 1984 † - syn of: Halkieria operculus (Z.X. Qian, 1984 †) - (HALKIERIIDAE) (FOSSIL)
- operiens, Sitala operiens E.R. Sykes, 1898 - (ARIOPHANTIDAE)
- operosa, Aldanella operosa Rozanov & Missarzhevsky, 1966 † - syn of: Aldanella attleborensis (Shaler & Foerste, 1888 †) - (ALDANELLIDAE) (FOSSIL)
- operta, Aplysia operta R.H. Burne, 1906 - syn of: Aplysia dactylomela P.C.A.S.L. Rang, 1828 - (APLYSIIDAE)
- opertanea, Lortiella opertanea W.F. Ponder & M. Bayer, 2003 - (HYRIIDAE)
- Opertochasma, Genus Opertochasma Stephenson, 1953 (PHOLADIDAE) (FOSSIL)
- opertus, Arcestes opertus Mojsisovics, 1875 † - (ARCESTIDAE) (FOSSIL)
- opertus, Sphenosphaera opertus (Foerste, 1893 †) - (BELLEROPHONTIDAE) (FOSSIL)
- ophelia, Therasia ophelia (L. Pfeiffer, 1855) - (CHAROPIDAE)
- ophelia, Holopea ophelia Billings, 1865 † - (HOLOPEIDAE) (FOSSIL)
- ophiaca, Eurytellina ophiaca W.P. Woodring, 1982 † - (TELLINIDAE) (FOSSIL)
- ophiarachnicola, Hemiliostraca ophiarachnicola H. Matsuda, D. Uyeno & K. Nagasawa, 2013 - (EULIMIDAE)
- Ophicardelus, Genus Ophicardelus H.H. Beck, 1837 (ELLOBIIDAE)
- Ophiceras, Genus Ophiceras Smith, 1932 (DIENEROCERATIDAE) (FOSSIL)
- OPHICERATIDAE Arthaber, 1911 - Family (CEPHALOPODA-AMMONOIDEA-CERATITIDA) (FOSSIL)
- ophidiana, Strophomenia ophidiana H. Heath, 1911 - (STROPHOMENIIDAE)
- ophidiastericola, Stilifer ophidiastericola T. Habe, 1951 - syn of: Stilifer utinomi T. Habe, 1951 - (EULIMIDAE)
- Ophidioceras, syn of: Genus Ophioceras Barrande, 1865 (OPHIDIOCERATIDAE) (FOSSIL)
- OPHIDIOCERATIDAE Hyatt, 1894 - Family (CEPHALOPODA-NAUTILOIDEA-TARPHYCERIDA) (FOSSIL)
- Ophidoceras, syn of: Genus Ophioceras Barrande, 1865 (OPHIDIOCERATIDAE) (FOSSIL)
- OPHIDOCERATIDAE - syn of Family: OPHIDIOCERATIDAE (FOSSIL)
- ophidoon, Luchuphaedusa ophidoon (H.A. Pilsbry, 1905) - (CLAUSILIIDAE)
- Ophieulima, Genus Ophieulima A. Warιn & M. Sibuet, 1981 (EULIMIDAE)
- Ophileta, Genus Ophileta Vanuxem, 1842 (OPHILETIDAE) (FOSSIL)
- OPHILETIDAE Koken, 1907 - Family (GASTROPODA-EOGASTROPODA-EUOMPHALINA) (FOSSIL)
- Ophiletina, Genus Ophiletina Ulrich & Scofield, 1897 (HELICOTOMIDAE) (FOSSIL)
- Ophilyroceras, Genus Ophilyroceras Ruzhentsev & Bogoslovskaya, 1971 (RHYMMOCERATIDAE) (FOSSIL)
- ophioacanthicola, Fuscapex ophioacanthicola A. Warén, 1981 - (EULIMIDAE)
- Ophioarachnicola, Genus Ophioarachnicola A. Warιn, 1980 (EULIMIDAE)
- Ophioceras, Genus Ophioceras Barrande, 1865 (OPHIDIOCERATIDAE) (FOSSIL)
- ophioderma, Ophiodermella ophioderma W.H. Dall, 1908 - syn of: Ophiodermella inermis (L.A. Reeve, 1843) - (BORSONIIDAE)
- ophioderma, Cerithium ophioderma (T. Habe, 1968) - (CERITHIIDAE)
- ophioderma, Ischnochiton ophioderma W.H. Dall, 1919 - syn of: Ischnochiton dispar (G.B. I Sowerby in W.J. Broderip & G.B. I Sowerby, 1832) - (ISCHNOCHITONIDAE)
- ophioderma, Pleurotoma ophioderma W.H. Dall, 1908 - syn of: Ophiodermella inermis (L.A. Reeve, 1843) - (TURRIDAE)
- Ophiodermella, Genus Ophiodermella P. Bartsch, 1944 (BORSONIIDAE)
- Ophiodermis, syn of: Genus Solaropsis H.H. Beck, 1837 (PLEURODONTIDAE)
- ophiodon, Dentalium ophiodon W.H. Dall, 1881 - syn of: Compressidens ophiodon (W.H. Dall, 1881) - (DENTALIIDAE)
- ophiodon, Melanella ophiodon W.H. Dall, 1927 - (EULIMIDAE)
- ophiodon, Compressidens ophiodon (W.H. Dall, 1881) - (PULSELLIDAE)
- Ophioglossolambis, Genus Ophioglossolambis A.M. Dekkers, 2012 (STROMBIDAE)
- Ophiogyra, syn of: Genus Polygyratia J.E. Gray, 1847 (CAMAENIDAE)
- ophioides, Thylacodes ophioides (P. Marshall & R. Murdoch, 1921 †) - (VERMETIDAE) (FOSSIL)
- Ophiolamia, Genus Ophiolamia A. Warιn & R. Carney, 1981 (EULIMIDAE)
- ophiomoerae, Punctifera ophiomoerae A. Warén, 1981 - (EULIMIDAE)
- Ophionautilus, Genus Ophionautilus Foord & Crick, 1890 (CENOCERATIDAE) (FOSSIL)
- ophione, Lamellaria ophione J.E. Gray, 1850 - (VELUTINIDAE)
- ophioneum, Alocolytoceras ophioneum (Benecke, 1865 †) - (LYTOCERATIDAE) (FOSSIL)
- ophioneus, Pselioceras ophioneus (L. Waagen, 1879 †) - (GRYPOCERATIDAE) (FOSSIL)
- ophioneus, Lecanites ophioneus L. Waagen, 1895 † - (LECANITIDAE) (FOSSIL)
- ophioneus, Nautilus ophioneus L. Waagen, 1879 † - syn of: Pselioceras ophioneus (L. Waagen, 1879 †) - (NAUTILIDAE) (FOSSIL)
- ophioneus, Prionolobus ophioneus (L. Waagen, 1895 †) - (PROPTYCHITIDAE) (FOSSIL)
- Ophiorhabdoceras, Genus Ophiorhabdoceras Tozer , 1994 (CYCLOCELTITIDAE) (FOSSIL)
- Ophiospila, syn of: Genus Solaropsis H.H. Beck, 1837 (PLEURODONTIDAE)
- ophir, Placostylus ophir W.J. Clench, 1941 - (BOTHRIEMBRYONTIDAE)
- ophirensis, Straparollus ophirensis J.W. Hall & R.P. Whitfield, 1877 † - (EUOMPHALIDAE) (FOSSIL)
- ophiura, Cerithiopsis ophiura A.A. Olsson & A. Harbison, 1953 - (CERITHIOPSIDAE)
- ophiuraphila, Mucronalia ophiuraphila T. Habe, 1974 - (EULIMIDAE)
- ophonia, Columbella ophonia P.L. Duclos, 1846 - syn of: Euplica varians (G.B. I Sowerby, 1832) - (COLUMBELLIDAE)
- ophthalmica, Chromodoris ophthalmica L.S.R. Bergh, 1905 - (CHROMODORIDIDAE)
- ophthalmophana, Hemiphaedusa ophthalmophana (J.F. Mabille, 1887) - (CLAUSILIIDAE)
- ophthalmophana cazioti, Hemiphaedusa ophthalmophana cazioti (A.R.J.B. Bavay & P. Dautzenberg, 1909) - (CLAUSILIIDAE)
- Opica, syn of: Subgenus Marmorana (Ambigua) C.A. Westerlund, 1902 (HELICIDAE)
- opifex, Modiolus opifex T. Say, 1825 - syn of: Gregariella coralliophaga opifex (T. Say, 1825) - (MYTILIDAE)
- opifex, Gregariella coralliophaga opifex (T. Say, 1825) - (MYTILIDAE)
- opiformis, Eritropis opiformis (R. Tate, 1896 †) - (ERITROPIDAE) (FOSSIL)
- opihiensis, Zafra opihiensis C.R. Laws, 1933 † - (COLUMBELLIDAE) (FOSSIL)
- opilaris, Glyptomelania glaphyrus opilaris (P.M.A. Morelet, 1851) - (PACHYCHILIDAE)
- opilina, Anodonta opilina I. Lea, 1852 - syn of: Anodonta cygnea (C. Linnaeus, 1758) - (UNIONIDAE)
- opima, Thysanodonta opima B.A. Marshall, 1995 - (CALLIOSTOMATIDAE)
- opima, Cystiscus opima (C.F. Laseron, 1957) - syn of: Granulina opima (C.F. Laseron, 1957) - (CYSTISCIDAE)
- opima, Homoctenus opima Li, 1995 † - (HOMOCTENIDAE) (FOSSIL)
- opima, Liaoningia opima Mi, Zhang & W.K.C. Sun 1993 † - (LIAONINGIIDAE) (FOSSIL)
- opima, Granulina opima (C.F. Laseron, 1957) - (MARGINELLIDAE)
- opima, Microginella opima C.F. Laseron, 1957 - syn of: Granulina opima (C.F. Laseron, 1957) - (MARGINELLIDAE)
- opima, Nuculoidea opima (J.W. Hall, 1843 †) - (NUCULIDAE) (FOSSIL)
- opima, Amalda opima (J. Marwick, 1924 †) - (OLIVIDAE) (FOSSIL)
- opima, Cylichnina opima (H.J. Finlay, 1926) - (RETUSIDAE)
- opima, Retusa truncatula opima K.O. Milaschewitsch, 1909 - (RETUSIDAE)
- opima, Ringicula opima Helwerda, 2015 - (RINGICULIDAE)
- opima, Shaanxiconcha opima Mi, Zhang & W.K.C. Sun, 1993 † - (SHAANXICONCHIDAE) (FOSSIL)
- opima, Marcia opima (J.F. Gmelin, 1791) - (VENERIDAE)
- opima, Venus opima J.F. Gmelin, 1791 - syn of: Marcia opima (J.F. Gmelin, 1791) - (VENERIDAE)
- opimacosta, Liracraea opimacosta Richardson, 1997 † - (MANGELIIDAE) (FOSSIL)
- Opimaphora, Genus Opimaphora C.F. Laseron, 1958 (TRIPHORIDAE)
- Opimarcia, Genus Opimarcia Marwick, 1948 (VENERIDAE) (FOSSIL)
- Opimaria, syn of: Genus Opimarcia Marwick, 1948 (VENERIDAE) (FOSSIL)
- opimata, Monachoides opimata É.A.A. Locard - syn of: Perforatella incarnata (O.F. Müller, 1774) - (HYGROMIIDAE)
- opimavoluta, Naticopsis opimavoluta E.G. Linsley, 1968 † - (DELPHINULOPSIDAE) (FOSSIL)
- Opimilda, Genus Opimilda T. Iredale, 1929 (MATHILDIDAE)
- opimum, Pachyrisma opimum (Dubar, 1948 †) - (PACHYRISMATIDAE) (FOSSIL)
- opimus, Agoniatites opimus (White & R.P. Whitfield, 1862 †) - (AGONIATITIDAE) (FOSSIL)
- opimus, Proplanulites opimus Buckman † - (AMMONOIDEA (unassigned)) (FOSSIL)
- opimus, Antillophos opimus K. Fraussen & G.T. Poppe, 2005 - (NASSARIIDAE)
- opimus, Sinoceltites opimus J.K. Zhao & al., 1978 † - (TAPASHANITIDAE) (FOSSIL)
- opinata, Retinella opinata S. Clessin, 1887 - (ZONITIDAE)
- opinatum, Ukhtoceras opinatum P.A. Zhuravleva, 1972 † - syn of: Ukhtoceras uchtense (Holzapfel, 1899 †) - (DISCOSORIDA (unassigned)) (FOSSIL)
- opiniosa, Diffalaba opiniosa T. Iredale, 1936 - (LITIOPIDAE)
- opiniosus, Onithochiton opiniosus T. Iredale & A.F.B. Hull, 1932 - syn of: Onithochiton neglectus A. de Rochebrune, 1881 - (CHITONIDAE)
- Opinorelia, syn of: Genus Omphalotropis L. Pfeiffer, 1851 (ASSIMINEIDAE)
- Opiotoptera, Genus Opiotoptera (PTERIIDA (unassigned)) (FOSSIL)
- opipara, Leptachatina opipara C.M. Cooke, 1910 - (AMASTRIDAE)
- opipara, Macrochlamys opipara H.H. Godwin-Austen - (ARIOPHANTIDAE)
- opipara, Sepia opipara (T. Iredale, 1926) - (SEPIIDAE)
- opipara, Glyptosepia opipara T. Iredale, 1926 - syn of: Sepia opipara (T. Iredale, 1926) - (SEPIIDAE)
- opipara manana, Leptachatina opipara manana H.A. Pilsbry & C.M. Cooke, 1914 - (AMASTRIDAE)
- opiparis, Melania opiparis P.M.A. Morelet, 1851 - syn of: Glyptomelania glaphyrus opilaris (P.M.A. Morelet, 1851) - (THIARIDAE)
- opiparus, Parachiton opiparus T. Iredale & A.F.B. Hull, 1925 - syn of: Leptochiton alveolus (S.L. Lovén, 1846 ex Sars MS) - (LEPTOCHITONIDAE)
- opiparus, Tirolites opiparus Zakharov & Smyshlyaeva, 2016 † - (TIROLITIDAE) (FOSSIL)
- opiranus, Turgenitubulus opiranus G.A. Solem, 1981 - (CAMAENIDAE)
- Opis, Genus Opis Defrance, 1824 (ASTARTIDAE) (FOSSIL)
- opis, Buccinum opis P.F. Röding, 1798 - syn of: Charonia lampas (C. Linnaeus, 1758) - (BUCCINIDAE)
- opis, Charonia opis P.F. Röding, 1798 - syn of: Charonia lampas (C. Linnaeus, 1758) - (RANELLIDAE)
- Opisocardium, syn of: Genus Lunulicardia J.E. Gray, 1853 (CARDIIDAE)
- Opisoma, Genus Opisoma Stoliczka, 1871 (ASTARTIDAE) (FOSSIL)
- opisoplectum, Buccinum opisoplectum W.H. Dall, 1907 - (BUCCINIDAE)
- opisthidia, Montereina opisthidia (L.S.R. Bergh, 1877) - (DISCODORIDIDAE)
- OPISTHOBRANCHIA (UNASSIGNED) - Family (GASTROPODA-HETEROBRANCHIA-OPISTHOBRANCHIA) (FOSSIL)
- opisthochetos, Ptychobela opisthochetos R.N. Kilburn, 1989 - (PSEUDOMELATOMIDAE)
- opisthoclinus, Paradoxipecten opisthoclinus Zhang, 1981 † - (AVICULOPECTINIDAE) (FOSSIL)
- opisthoclinus, Hunanopecten opisthoclinus Wang, 1993 † - (HUNANOPECTINIDAE) (FOSSIL)
- opisthocoele, Opisthocoelicum opisthocoele C. de la Torre & P. Bartsch, 1941 - (POMATIIDAE)
- Opisthocoelicum, Genus Opisthocoelicum C. de la Torre & P. Bartsch, 1941 (POMATIIDAE)
- Opisthocoelus, Genus Opisthocoelus Beushausen, 1895 (PRAECARDIOIDEA (unassigned)) (FOSSIL)
- opisthocostae, Turbonilla opisthocostae A. Peñas & E. Rolán, 2010 - (PYRAMIDELLIDAE)
- Opisthodermella, syn of: Genus Mohnia H.B.S. Friele, 1879 (BUCCINIDAE)
- opisthodon, Truncatellina opisthodon (O.W.H. Reinhardt, 1879) - (VERTIGINIDAE)
- Opistholoba, syn of: Genus Opisthoptera Meek, 1871 (AMBONYCHIIDAE) (FOSSIL)
- Opisthonema, Genus Opisthonema Yu, 1974 (OPISTHONEMATIDAE) (FOSSIL)
- OPISTHONEMATIDAE Yu, 1976 - Family (GASTROPODA-EOGASTROPODA-EUOMPHALINA) (FOSSIL)
- Opisthoporus, Subgenus Cyclotus (Opisthoporus) L. Pfeiffer, 1851 (CYCLOPHORIDAE)
- Opisthoptera, Genus Opisthoptera Meek, 1871 (AMBONYCHIIDAE) (FOSSIL)
- Opisthorchophorus, Genus Opisthorchophorus V.I. Beriozkina, R.E. Levina & Y.I. Starobogatov, 1995 (BITHYNIIDAE)
- Opisthosiphon, Genus Opisthosiphon W.H. Dall, 1905 (POMATIIDAE)
- Opisthosiphona, syn of: Genus Opisthosiphon W.H. Dall, 1905 (POMATIIDAE)
- opisthostenus, Calliostoma opisthostenus C.F. Fontannes, 1879 † - (CALLIOSTOMATIDAE) (FOSSIL)
- Opisthostoma, Genus Opisthostoma H.F. Blanford & W.T. Blanford, 1860 (DIPLOMMATINIDAE)
- OPISTHOTEUTHIDAE Verrill, 1896 - Family (CEPHALOPODA-COLEOIDEA-OCTOPODIFORMES-OCTOPODA-CIRRATA)
- Opisthoteuthis, Genus Opisthoteuthis A.E. Verrill, 1883 (OPISTHOTEUTHIDAE)
- Opisthotrigonia, Genus Opisthotrigonia Cox, 1952 (TRIGONIIDAE) (FOSSIL)
- opistochetos, Ptychobela opistochetos R.N. Kilburn, 1989 - syn of: Ptychobela opisthochetos R.N. Kilburn, 1989 - (PSEUDOMELATOMIDAE)
- opistodon, Truncatellina opistodon O.W.H. Reinhardt, 1879 - syn of: Truncatellina opisthodon (O.W.H. Reinhardt, 1879) - (VERTIGINIDAE)
- opitzi, Ivoites opitzi De Baets & al., 2013 † - (MIMOSPHINCTIDAE) (FOSSIL)
- opmei, Potamides opmei C.J. Maury, 1917 † - (POTAMIDIDAE) (FOSSIL)
- opoboensis, Gulella opoboensis H.B. Preston, 1914 - (STREPTAXIDAE)
- opoboensis liberiana, Gulella opoboensis liberiana E. Degner, 1934 - (STREPTAXIDAE)
- opoitia, Protoginella opoitia (J. Marwick, 1965 †) - (MARGINELLIDAE) (FOSSIL)
- opoitius, Zeacolpus opoitius J. Marwick, 1965 † - (TURRITELLIDAE) (FOSSIL)
- Opokiella, Genus Opokiella Plotnikov, 1949 (PALAEANODONTIDAE) (FOSSIL)
- oppeli, Alaria oppeli H. Rolle, 1860 † - syn of: Diarthema munsterianum (A.V.M.D. D'Orbigny, 1850 †) - (APORRHAIDAE) (FOSSIL)
- oppeli, Zittelia oppeli (Etallon†) - (COLOMBELLINIDAE) (FOSSIL)
- oppeli, Berriasella oppeli (Kilian, 1889 †) - (NEOCOMITIDAE) (FOSSIL)
- oppeli, Oxycerites oppeli S. Elmi, 1967 † - (OPPELIIDAE) (FOSSIL)
- oppeli, Pseudaganides oppeli (C.A. von Zittel, 1868 †) - (PSEUDONAUTILIDAE) (FOSSIL)
- oppeli, Ptychites oppeli (Mojsisovic, 1882 †) - (PTYCHITIDAE) (FOSSIL)
- Oppelia, Genus Oppelia Waagen in Benecke, 1869 (OPPELIIDAE) (FOSSIL)
- OPPELIIDAE Bonarelli, 1894 - Family (CEPHALOPODA-AMMONOIDEA-AMMONITIDA) (FOSSIL)
- oppeliiformis, Praeoppelia oppeliiformis Westermann, 1969 † - (OPPELIIDAE) (FOSSIL)
- Oppelina, Genus Oppelina Buckman, 1926 (MOLLUSCA INCERTAE SEDIS) (FOSSIL)
- oppenheimi, Cordieria oppenheimi A.E.M. Cossmann & G. Pissarro † - (BORSONIIDAE) (FOSSIL)
- oppenheimi, Venericardia oppenheimi A.E.M. Cossmann, 1904 † - (CARDITIDAE) (FOSSIL)
- oppenheimi, Divaricella oppenheimi R.B. Newton, 1922 † - (LUCINIDAE) (FOSSIL)
- oppenheimi, Jenneria oppenheimi E.W. Vredenburg, 1921 † - (PEDICULARIIDAE) (FOSSIL)
- oppenheimi, Odostomia oppenheimi A.E.M. Cossmann, 1903 † - (PYRAMIDELLIDAE) (FOSSIL)
- oppenheimi, Amplogladius oppenheimi (O.S. Adegoke, 1977 †) - (ROSTELLARIIDAE) (FOSSIL)
- oppenheimi, Peronaea oppenheimi Bohm & Weisfermel, 1913 † - (TELLINIDAE) (FOSSIL)
- Oppenheimiella, syn of: Genus Gibbulinella W.A. Wenz, 1920 (STREPTAXIDAE)
- Oppenheimopecten, Subgenus Pecten (Oppenheimopecten) Teppner, 1922 (PECTINIDAE) (FOSSIL)
- oppenoorthi, Brotia oppenoorthi C.H. Oostingh, 1935 † - (PACHYCHILIDAE) (FOSSIL)
- oppenoorthi, Marcia oppenoorthi C.H. Oostingh, 1935 † - (VENERIDAE) (FOSSIL)
- oppenoorthi exserta, Brotia oppenoorthi exserta C.H. Oostingh, 1935 - (PACHYCHILIDAE)
- oppenoorthi semiglabrata, Brotia oppenoorthi semiglabrata C.H. Oostingh, 1935 - (PACHYCHILIDAE)
- oppessulata, Tropidophora oppessulata E. Fischer-Piette, F. Blanc & F. Salvat, 1969 - (POMATIIDAE)
- oppidanus, Potamopyrgus oppidanus M. Haase, 2008 - (TATEIDAE)
- oppidi, Pyrenaearia oppidi P. Fagot, 1885 - syn of: Pyrenaearia carascalensis (A. Michaud, 1831) - (HYGROMIIDAE)
- oppidulum, Perrottetia oppidulum (A.R.J.B. Bavay & P. Dautzenberg, 1908) - (STREPTAXIDAE)
- oppilata, Helix oppilata P.M.A. Morelet, 1849 - syn of: Linisia oppilata (P.M.A. Morelet, 1849) - (HELICIDAE)
- oppilata, Linisia oppilata (P.M.A. Morelet, 1849) - (POLYGYRIDAE)
- oppilata complicata, Poligyra oppilata complicata H.A. Pilsbry, 1910 - syn of: Linisia oppilata (P.M.A. Morelet, 1849) - (HELICIDAE)
- oppilata implicata, Polygyra oppilata implicata E.C. Von Martens, 1865 - syn of: Linisia implicata (E.C. Von Martens, 1865) - (POLYGYRIDAE)
- Oppletora, syn of: Genus Isidorella R. Tate, 1896 (PLANORBIDAE)
- oppletum, Vaginoceras oppletum (Ruedemann, 1906 †) - (ENDOCERATIDAE) (FOSSIL)
- Oppomorus, Subgenus Morula (Oppomorus) T. Iredale, 1937 (MURICIDAE)
- opportuna, Cerithium nodulosum opportuna C.É. Bayle, 1880 - (CERITHIIDAE)
- opportuna, Auriculodes opportuna A.A. Gould - syn of: Auriculodes pallidum (G.B. II Sowerby, 1839) - (ELLOBIIDAE)
- opportuna, Gadila opportuna J.T. Kuroda & T. Habe in T. Habe, 1961 - (GADILIDAE)
- opportunatum, Ellobium opportunatum A.A. Gould, 1859 - (ELLOBIIDAE)
- Opposirius, syn of: Genus Sirius C. Hedley, 1900 (CAPULIDAE)
- opposita, Sodaliscala opposita M.E.A. de Boury, 1921 - syn of: Epitonium oppositum (M.E.A. de Boury, 1921) - (EPITONIIDAE)
- opposita, Helix opposita C.A. Westerlund, 1898 - syn of: Fruticicola stoliczkana (G. Nevill, 1878) - (HELICIDAE)
- opposita, Luciella alata opposita (Lindström, 1884 †) - (LUCIELLIDAE) (FOSSIL)
- opposita, Mactra opposita L.A. Reeve, 1854 - (MACTRIDAE)
- opposita, Turrithyra sinuosa opposita (C. de la Torre & P. Bartsch, 1938) - (POMATIIDAE)
- opposita, Lyria opposita T. Iredale, 1937 - syn of: Lyria pattersonia (G. Perry, 1811) - (VOLUTIDAE)
- oppositum, Epitonium oppositum (M.E.A. de Boury, 1921) - (EPITONIIDAE)
- oppositum, Stylonema oppositum J. Perner, 1907 † - (LOXONEMATIDAE) (FOSSIL)
- oppositus, Mallorisiphon oppositus T. Iredale, 1940 - (SIPHONARIIDAE)
- oppressa, Emarginula oppressa K.H. Barnard, 1963 - (FISSURELLIDAE)
- oppressa, Emarginula oppressa K.H. Barnard, 1958 - syn of: Emarginula oppressa K.H. Barnard, 1963 - (FISSURELLIDAE)
- oppressa, Nucula oppressa W. Bergmans, 1991 - (NUCULIDAE)
- oppressus, Oxychilus oppressus (R.J. Shuttleworth, 1877) - (OXYCHILIDAE)
- oppressus, Trochus oppressus (F.W. Hutton, 1878) - (TROCHIDAE)
- oppressus dunedinensis, Trochus oppressus dunedinensis H.H. Suter, 1907 - syn of: Coelotrochus chathamensis dunedinensis (H.H. Suter, 1897) - (TROCHIDAE)
- opsimathes, Lienardia opsimathes J.C. Melvill & R. Standen, 1903 - syn of: Lienardia soror (E.A. Smith, 1882) - (CLATHURELLIDAE)
- opsitelotus, Solariorbis opsitelotus (W.H. Dall, 1892 †) - (TORNIDAE) (FOSSIL)
- optabile, Epitonium optabile (A. Adams, 1873) - (EPITONIIDAE)
- optabilis, Leptachatina optabilis C.M. Cooke, 1911 - (AMASTRIDAE)
- optabilis, Awateria optabilis (R. Murdoch & H.H. Suter, 1906) - (BORSONIIDAE)
- optabilis, Leptoconus optabilis A. Adams, 1855 - syn of: Gradiconus philippii (L.C. Kiener, 1847) - (CONIDAE)
- optabilis, Drillia optabilis R. Murdoch & H.H. Suter, 1906 - syn of: Awateria optabilis (R. Murdoch & H.H. Suter, 1906) - (DRILLIIDAE)
- optabilis, Vexitomina optabilis R. Murdoch & H.H. Suter, 1906 - syn of: Awateria optabilis (R. Murdoch & H.H. Suter, 1906) - (HORAICLAVIDAE)
- optabilis, Eucithara optabilis G.B. III Sowerby, 1907 - syn of: Eucithara coronata (R.B. Hinds, 1843) - (MANGELIIDAE)
- optabilis, Cythara optabilis G.B. III Sowerby, 1907 - syn of: Eucithara coronata (R.B. Hinds, 1843) - (MANGELIIDAE)
- optabilis, Margarites optabilis P.P. Carpenter, 1864 - syn of: Lirularia optabilis (P.P. Carpenter, 1864) - (MARGARITIDAE)
- optabilis, Lirularia optabilis (P.P. Carpenter, 1864) - (TROCHIDAE)
- optapa, Odostomia optapa M. Yokoyama, 1920 - (PYRAMIDELLIDAE)
- optata, Amaea optata (F.P. Jousseaume, 1912) - (EPITONIIDAE)
- optata, Sonorella optata H.A. Pilsbry & J.H. Ferriss, 1910 - (HELMINTHOGLYPTIDAE)
- optata, Nassa optata A.A. Gould, 1860 - syn of: Nassarius nigellus (L.A. Reeve, 1854) - (NASSARIIDAE)
- optata, Odostomia optata M. Yokoyama, 1920 - (PYRAMIDELLIDAE)
- optata, Lucerapex optata E.A. Smith, 1899 - syn of: Lucerapex indagatoris (H.J. Finlay, 1927) - (TURRIDAE)
- optatum, Peismoceras optatum (Barrande, 1865 †) - (LECHRITROCHOCERATIDAE) (FOSSIL)
- optatum, Paraschistoceras optatum Ruzhentsev, 1950 † - (SCHISTOCERATIDAE) (FOSSIL)
- optatus, Fractolatirus optatus (P. Marshall & R. Murdoch, 1923 †) - (FASCIOLARIIDAE) (FOSSIL)
- optatus, Chlamys parisiensis optatus G.P. Deshayes, 1864 - (PECTINIDAE)
- optatus, Trochus optatus G.B. II Sowerby, 1838 - (TROCHIDAE)
- Optediceros, syn of: Genus Assiminea J. Fleming, 1828 (ASSIMINEIDAE)
- Opterigone, syn of: Genus Discoconcha B. Rensch, 1937 (CAMAENIDAE)
- opthanta, Anadara opthanta W.P. Woodring, 1925 † - (ARCIDAE) (FOSSIL)
- optima, Rasenia optima Mesezhnikov, 1984 † - (AULACOSTEPHANIDAE) (FOSSIL)
- optima, Microdrillia optima (K.H.J. Thiele, 1925) - (BORSONIIDAE)
- optima, Trishoplita optima H.A. Pilsbry, 1902 - (BRADYBAENIDAE)
- optima, Metula optima A.A. Olsson & F.M. Bayer, 1972 - (BUCCINIDAE)
- optima, Ganesella optima H.A. Pilsbry, 1902 - (CAMAENIDAE)
- optima, Cuspidaria optima G.B. III Sowerby, 1904 - (CUSPIDARIIDAE)
- optima, Amaea optima (J.C. Melvill & R. Standen, 1903) - (EPITONIIDAE)
- optima, Epitonium optima J.C. Melvill & R. Standen, 1903 - syn of: Amaea optima (J.C. Melvill & R. Standen, 1903) - (EPITONIIDAE)
- optima, Euciroa optima G.B. III Sowerby, 1894 - syn of: Euciroa eburnea (J. Wood-Mason & A. Alcock, 1891) - (EUCIROIDAE)
- optima, Ogasawarana optima (A.J. Wagner, 1905) - (HELICINIDAE)
- optima, Amalda optima (G.B. III Sowerby, 1897) - (OLIVIDAE)
- optima, Scutellastra optima (H.A. Pilsbry, 1907) - (PATELLIDAE)
- optima, Verticordia optima G.B. III Sowerby, 1894 - syn of: Euciroa eburnea (J. Wood-Mason & A. Alcock, 1891) - (VERTICORDIIDAE)
- optimum, Calliostoma optimum A. de Rochebrune & J.F. Mabille, 1891 - syn of: Calliostoma nudum (R.A. Philippi, 1845) - (CALLIOSTOMATIDAE)
- optimum, Argopecten thetidis optimum J. Brown & H.A. Pilsbry, 1913 - (PECTINIDAE)
- optimus, Ceratites nodosus optimus Penndorf, 1951 † - (CERATITIDAE) (FOSSIL)
- optimus, Conus optimus G.B. III Sowerby, 1913 - syn of: Fulgiconus exiguus (J.B.P.A. Lamarck, 1810) - (CONIDAE)
- optimus, Nassarius optimus (G.B. III Sowerby, 1903) - (NASSARIIDAE)
- optimus, Antillophos optimus K. Fraussen & G.T. Poppe, 2005 - syn of: Antillophos opimus K. Fraussen & G.T. Poppe, 2005 - (NASSARIIDAE)
- optimus, Pyrgiscus optimus (S. Nomura, 1936) - (PYRAMIDELLIDAE)
- optio, Boucardicus optio E. Fischer-Piette, Ch.P. Blanc, F. Blanc & F. Salvat, 1993 - (CYCLOPHORIDAE)
- optiva, Pyrgiscilla optiva S. Nomura, 1937 - syn of: Pyrgiscus optivus (S. Nomura, 1937) - (PYRAMIDELLIDAE)
- optiva, Siphonaria optiva T. Iredale, 1940 - syn of: Siphonaria laciniosa (C. Linnaeus, 1758) - (SIPHONARIIDAE)
- optivus, Pyrgiscus optivus (S. Nomura, 1937) - (PYRAMIDELLIDAE)
- Optoturris, Genus Optoturris Powell, 1944 (NEOGASTROPODA (unassigned)) (FOSSIL)
- Opularca, syn of: Genus Barbatia J.E. Gray, 1847 (ARCIDAE)
- opulens, Columbella opulens L.H. Woolacott, 1957 - syn of: Pyrene punctata (J.G. Bruguière, 1789) - (COLUMBELLIDAE)
- opulenta, Tropidoturris opulenta K.H.J. Thiele, 1925 - syn of: Tropidoturris scitecosta (G.B. III Sowerby, 1903) - (BORSONIIDAE)
- opulenta, Limea opulenta (K.H.J. Thiele, 1920) - (LIMIDAE)
- opulenta, Calorhadia opulenta † - (NUCULANIDAE) (FOSSIL)
- opulenta, Comitas opulenta (K.H.J. Thiele, 1925) - (PSEUDOMELATOMIDAE)
- opulenta, Polystira opulenta P.O. Jung, 1971 † - (TURRIDAE) (FOSSIL)
- opulenta, Glyptozaria opulenta (C. Hedley, 1907) - (TURRITELLIDAE)
- opulentus, Joculator opulentus A. Cecalupo & I. Perugia, 2013 - (CERITHIOPSIDAE)
- opulentus, Pectinatites opulentus S.S. Buckman † - (PERISPHINCTIDAE) (FOSSIL)
- opulentus, Ptychites opulentus (Mojsisovics, 1882 †) - (PTYCHITIDAE) (FOSSIL)
- opuntia, Okenia opuntia K. Baba, 1960 - (GONIODORIDIDAE)
- opuntia, Okenia opuntia N. Coleman, 2001 - syn of: Okenia echinata K. Baba, 1949 - (GONIODORIDIDAE)
- opuntia, Micrarionta opuntia B. Roth, 1975 - (HELMINTHOGLYPTIDAE)
- opuntia, Chlamys opuntia W.H. Dall, 1898 † - (PECTINIDAE) (FOSSIL)
- opuraensis, Acar opuraensis (Powell & J.A. Bartrum, 1928 †) - (ARCIDAE) (FOSSIL)
- opuraensis, Crypta opuraensis J.A. Bartrum & A.W.B. Powell, 1928 † - syn of: Maoricrypta radiata (F.W. Hutton, 1873 †) - (CALYPTRAEIDAE) (FOSSIL)
- opuraensis, Tugali opuraensis J.A. Bartrum & Powell, 1928 † - (FISSURELLIDAE) (FOSSIL)
- oquirrhensis, Oreohelix haydeni oquirrhensis (H. Hemphill, 1886) - (OREOHELICIDAE)
- ora, Sonorelix borrogoensis ora (G. Willett, 1929) - (HELMINTHOGLYPTIDAE)
- ora, Austropyrgus ora A. Clark, W.B. Miller & W.F. Ponder, 2003 - (HYDROBIIDAE)
- ora, Chrysallida ora (C.F. Laseron, 1959) - (PYRAMIDELLIDAE)
- Oracardia, Genus Oracardia Herrick, 1888 (PRAECARDIIDAE) (FOSSIL)
- oradovekaiae, Scalites oradovekaiae (Vostokova, 1964 †) - (RAPHISTOMATIDAE) (FOSSIL)
- oradovekaiae, Omulevia oradovekaiae Vostokova, 1964 † - syn of: Scalites oradovekaiae (Vostokova, 1964 †) - (RAPHISTOMATIDAE) (FOSSIL)
- orahovacensis, Gyraulus orahovacensis (P.S. Pavlovic, 1903) - (PLANORBIDAE)
- oralis, Vertigo oralis V. Sterki, 1898 - (VERTIGINIDAE)
- oranensis, Ferussacia oranensis J.R. Bourguignat, 1868 - (FERUSSACIIDAE)
- oranensis, Cernuella oranensis (P.M.A. Morelet, 1852) - (HYGROMIIDAE)
- oranensis, Melanopsis magnifica oranensis P.M. Pallary, 1911 - (MELANOPSIDAE)
- orangensis, Barycypraea orangensis C. Beets, 1942 † - (CYPRAEIDAE) (FOSSIL)
- Orangia, Genus Orangia G.A. Solem, 1976 (ENDODONTIDAE)
- orangica, Leda orangica A. de Rochebrune & J.F. Mabille, 1889 - syn of: Neilonella sulculata (A.A. Gould, 1852) - (NUCULANIDAE)
- orani, Curvella orani E. Fischer-Piette & al., 1994 - (SUBULINIDAE)
- Orania, Genus Orania P.M. Pallary, 1900 (MURICIDAE)
- oranica, Schilderia oranica J.C.H. Crosse, 1896 - syn of: Schilderia achatidea (J.E. Gray in G.B. I Sowerby, 1837) - (CYPRAEIDAE)
- oranica, Alexia oranica P.M. Pallary, 1900 - syn of: Myosotella denticulata (G. Montagu, 1803) - (ELLOBIIDAE)
- oranica, Rissoa oranica P.M. Pallary, 1900 - syn of: Alvania scabra oranica (P.M. Pallary, 1900) - (RISSOIDAE)
- oranica, Alvania scabra oranica (P.M. Pallary, 1900) - (RISSOIDAE)
- Oraniceras, Genus Oraniceras Mitta, 2015 (PARKINSONIIDAE) (FOSSIL)
- oraria, Amalda oraria (Olson, 1956 †) - (OLIVIDAE) (FOSSIL)
- orariana, Ividella orariana W.H. Dall & P. Bartsch, 1909 - syn of: Ividella notabilis (C.B. Adams, 1852) - (PYRAMIDELLIDAE)
- orariana, Pleurotomella orariana (W.H. Dall, 1908) - (RAPHITOMIDAE)
- Oratoceras, Genus Oratoceras Zhuravleva, 1964 (ONCOCERIDA (unassigned)) (FOSSIL)
- orba, Solatisonax orba R. Bieler, 1993 - (ARCHITECTONICIDAE)
- orba, Campylaea orba M. von Kimakowicz, 1890 - syn of: Faustina faustina associata (E.A. Rossmässler, 1835) - (HELICIDAE)
- orba, Gemmula orba J. Marwick, 1931 † - (TURRIDAE) (FOSSIL)
- orbella, Crepidula orbella M. Yokoyama, 1922 - syn of: Ergaea walshi (L.A. Reeve, 1859) - (CALYPTRAEIDAE)
- orbella, Lucina orbella A.A. Gould, 1851 - syn of: Diplodonta orbella (Gould, 1851) - (LUCINIDAE)
- orbella, Diplodonta orbella (Gould, 1851) - (UNGULINIDAE)
- orbellus, Tornus orbellus (A. Adams, 1861) - (TORNIDAE)
- orbica, Circe orbica L.A. Reeve, 1863 - syn of: Circe tumefacta G.B. II Sowerby, 1851 - (VENERIDAE)
- orbicella, Goniatites orbicella J.W. Hall, 1860 † - syn of: Tornoceras orbicella (J.W. Hall, 1860 †) - (GONIATITIDAE) (FOSSIL)
- orbicella, Nucula orbicella A.A. Olsson, 1922 † - (NUCULIDAE) (FOSSIL)
- orbicella, Tornoceras orbicella (J.W. Hall, 1860 †) - (TORNOCERATIDAE) (FOSSIL)
- orbicula, Benthocardiella orbicula A.W.B. Powell, 1930 - (CONDYLOCARDIIDAE)
- orbicula, Cosa orbicula C.R. Laws, 1950 † - (PHILOBRYIDAE) (FOSSIL)
- orbicula, Biomphalaria orbicula (P.M.A. Morelet, 1849) - (PLANORBIDAE)
- orbiculare, Entolium orbiculare Sowerby † - (ENTOLIIDAE) (FOSSIL)
- orbiculare, Goniatites orbiculare G.G. Münster, 1832 † - syn of: Sporadoceras orbiculare (G.G. Münster, 1832 †) - (GONIATITIDAE) (FOSSIL)
- orbiculare, Periploma orbiculare R.J.L. Guppy, 1882 - (PERIPLOMATIDAE)
- orbiculare, Amphidesma orbiculare L.H. Hupé in C. Gay, 1854 - syn of: Semele solida Gray, 1828 - (SEMELIDAE)
- orbiculare, Sporadoceras orbiculare (G.G. Münster, 1832 †) - (SPORADOCERATIDAE) (FOSSIL)
- orbiculare, Tonna orbiculare G. Perry, 1811 - syn of: Tonna dolium (C. Linnaeus, 1758) - (TONNIDAE)
- orbicularia, Strophiops orbicularia (C.J. Maynard, 1889) - (CERIONIDAE)
- Orbicularia, Genus Orbicularia G.P. Deshayes, 1850 (PHARIDAE)
- orbicularis, Ambonychia orbicularis (E. Emmons, 1842 †) - (AMBONYCHIIDAE) (FOSSIL)
- orbicularis, Eriphylopsis orbicularis (Sowerby, 1823 †) - (ASTARTIDAE) (FOSSIL)
- orbicularis, Cyclocardia orbicularis (E. Forbes, 1846 †) - (CARDITIDAE) (FOSSIL)
- orbicularis, Dendrodoris orbicularis Á. Valdés, 2001 - (DENDRODORIDIDAE)
- orbicularis, Glycymeris orbicularis G.F. Angas, 1879 - syn of: Tucetona flabellata (J.E. Tenison-Woods, 1877) - (GLYCYMERIDIDAE)
- orbicularis, Glycymeris orbicularis E.M. Da Costa, 1778 - syn of: Glycymeris glycymeris (C. Linnaeus, 1758) - (GLYCYMERIDIDAE)
- orbicularis, Glycymeris orbicularis K. Martin, 1887 - syn of: Glycymeris martini Finlay, 1927 - (GLYCYMERIDIDAE)
- orbicularis, Glycymeris orbicularis G.F. Angas, 1879 - syn of: Tucetona flabellata (J.E. Tenison-Woods, 1877) - (GLYCYMERIDIDAE)
- orbicularis, Goniatites orbicularis G.G. Münster, 1832 † - syn of: Sporadoceras muensteri (von Buch, 1832 †) - (GONIATITIDAE) (FOSSIL)
- orbicularis, Cardiomorpha orbicularis McCoy † - (GRAMMYSIIDAE) (FOSSIL)
- orbicularis, Hermaea orbicularis A. da Costa, 1866 - syn of: Placida dendritica (J. Alder & A. Hancock, 1843) - (HERMAEIDAE)
- orbicularis, Hexabranchus orbicularis F.D. Abraham, 1877 - syn of: Hexabranchus sanguineus (W.P.E.S. Rüppell & F.S. Leuckart, 1830) - (HEXABRANCHIDAE)
- orbicularis, Isoarca orbicularis R. Tate, 1896 † - syn of: Joannites subdiffissus (Mojsisovics, 1875 †) - (ISOARCIDAE) (FOSSIL)
- orbicularis, Kellia orbicularis Wood, 1840 † - syn of: Aligena orbicularis (Wood, 1840 †) - (KELLIIDAE) (FOSSIL)
- orbicularis, Aligena orbicularis (Wood, 1840 †) - (LASAEIDAE) (FOSSIL)
- orbicularis, Patelloida orbicularis J.R.C. Quoy & J.P. Gaimard, 1834 - (LOTTIIDAE)
- orbicularis, Codakia orbicularis (C. Linnaeus, 1758) - (LUCINIDAE)
- orbicularis, Lucina orbicularis G.P. Deshayes, 1836 † - (LUCINIDAE) (FOSSIL)
- orbicularis, Lucina orbicularis C. Linnaeus, 1758 - syn of: Codakia orbicularis (C. Linnaeus, 1758) - (LUCINIDAE)
- orbicularis, Johnmartinia orbicularis (R. Tate, 1896 †) - (MALLETIIDAE) (FOSSIL)
- orbicularis, Monocondylus orbicularis P.M.A. Morelet, 1866 - syn of: Pseudodon cambodjensis (S.A.A. Petit De La Saussaye, 1865) - (MYCETOPODIDAE)
- orbicularis, Neoschizodus orbicularis (H.G. Bronn, 1837 †) - (MYOPHORIIDAE) (FOSSIL)
- orbicularis, Mytilus orbicularis P.M. Pallary, 1903 - syn of: Mytilus galloprovincialis J.B.P.A. Lamarck, 1819 - (MYTILIDAE)
- orbicularis, Fasciculiconcha orbicularis Yin, 1983 † - (PECTINIDA (unassigned)) (FOSSIL)
- orbicularis, Chlamys orbicularis G.B. II Sowerby, 1842 - syn of: Lissochlamys exotica (L.W. Dillwyn, 1817) - (PECTINIDAE)
- orbicularis, Orbicularia orbicularis G.P. Deshayes, 1839 - syn of: Orbicularia orbiculata (W. Wood, 1828) - (PHARIDAE)
- orbicularis, Elizia orbicularis W. Wood, 1828 - syn of: Orbicularia orbiculata (W. Wood, 1828) - (PHARIDAE)
- orbicularis, Placuna orbicularis L. Philipsson, 1788 - syn of: Placuna placenta (C. Linnaeus, 1758) - (PLACUNIDAE)
- orbicularis, Placuna orbicularis L. Philipsson, 1788 - syn of: Placuna placenta (C. Linnaeus, 1758) - (PLACUNIDAE)
- orbicularis, Ancylus orbicularis F. Held, 1837 - (PLANORBIDAE)
- orbicularis, Lindbergia orbicularis F. Riedel, 1962 - (PRISTILOMATIDAE)
- orbicularis, Lyroschizodus orbicularis (Newell & Boyd, 1975 †) - (SCHIZODIDAE) (FOSSIL)
- orbicularis, Xinanopecten orbicularis S.Y. Feng & al., 1992 † - (STREBLOCHONDRIIDAE) (FOSSIL)
- orbicularis, Leporimetis orbicularis (G.B. III Sowerby, 1889) - (TELLINIDAE)
- orbicularis, Tellina orbicularis G.B. III Sowerby, 1889 - syn of: Leporimetis orbicularis (G.B. III Sowerby, 1889) - (TELLINIDAE)
- orbicularis, Latitrigonia orbicularis Kobayashi, 1957 † - (TRIGONIIDAE) (FOSSIL)
- orbicularis, Lyrioschizodus orbicularis Newell & Boyd, 1975 † - syn of: Lyroschizodus orbicularis (Newell & Boyd, 1975 †) - (TRIGONIIDAE) (FOSSIL)
- orbicularis, Anodon orbicularis P.M. Heude, 1880 - syn of: Sinanodonta woodiana (I. Lea, 1834) - (UNIONIDAE)
- orbicularis, Periglypta orbicularis (Hislop, 1859 †) - (VENERIDAE) (FOSSIL)
- orbicularis, Dosinia orbicularis A.E.R. Agassiz, 1845 † - (VENERIDAE) (FOSSIL)
- orbicularis, Venus orbicularis C. Linnaeus, 1758 - syn of: Codakia orbicularis (C. Linnaeus, 1758) - (VENERIDAE)
- orbicularis, Venus orbicularis auct. non C. Linnaeus, 1758 - syn of: Codakia distinguenda (G.W. Tryon, 1872) - (VENERIDAE)
- orbicularis, Yoldiella orbicularis O.A. Scarlato, 1981 - (YOLDIIDAE)
- orbicularis chamaeformis, Cyclocardia orbicularis chamaeformis (J. de C. Sowerby, 1825 †) - (CARDITIDAE) (FOSSIL)
- orbicularis paucicostata, Cyclocardia orbicularis paucicostata A. Krause, 1885 † - (CARDITIDAE) (FOSSIL)
- orbiculata, Anatoma orbiculata D.L. Geiger, 2012 - (ANATOMIDAE)
- orbiculata, Bathyarca orbiculata (W.H. Dall, 1881) - (ARCIDAE)
- orbiculata, Crepipatella orbiculata (W.H. Dall, 1919) - (CALYPTRAEIDAE)
- orbiculata, Crepidula orbiculata W.H. Dall, 1919 - syn of: Crepipatella orbiculata (W.H. Dall, 1919) - (CALYPTRAEIDAE)
- orbiculata, Granata orbiculata (C.B. Adams, 1850) - (CHILODONTIDAE)
- orbiculata, Hemicycla orbiculata W. Wood, 1828 - syn of: Hemicycla plicaria (J.B.P.A. Lamarck, 1816) - (HELICIDAE)
- orbiculata, Olygyra orbiculata (T. Say, 1818) - (HELICINIDAE)
- orbiculata, Helicina orbiculata A.J. Wagner, 1910 - syn of: Olygyra orbiculata (T. Say, 1818) - (HELICINIDAE)
- Orbiculata, syn of: Genus Olygyra T. Say, 1818 (HELICINIDAE)
- orbiculata, Hercoglossa orbiculata (M. Tuomey, 1854 †) - (HERCOGLOSSIDAE) (FOSSIL)
- orbiculata, Pyrgulopsis orbiculata R. Hershler, 1998 - (HYDROBIIDAE)
- orbiculata, Ctena orbiculata (G. Montagu, 1808) - (LUCINIDAE)
- orbiculata, Codakia orbiculata G. Montagu, 1808 - syn of: Ctena orbiculata (G. Montagu, 1808) - (LUCINIDAE)
- orbiculata, Mesocochliopa orbiculata Zhu, 1980 † - (MESOCOCHLIOPIDAE) (FOSSIL)
- orbiculata, Septimyalina orbiculata Newell, 1942 † - (MYALINIDAE) (FOSSIL)
- orbiculata, Mya orbiculata L. Spengler, 1793 - syn of: Scrobicularia plana (E.M. Da Costa, 1778) - (MYIDAE)
- orbiculata, Nassa orbiculata A. Adams, 1852 - syn of: Nassarius kraussianus (R.W. Dunker, 1846) - (NASSARIIDAE)
- orbiculata, Neritaria orbiculata (Stoppani, 1858 †) - (NERITARIIDAE) (FOSSIL)
- orbiculata, Orbicularia orbiculata (W. Wood, 1828) - (PHARIDAE)
- orbiculata, Philobrya orbiculata C. Hedley, 1916 - syn of: Philobrya sublaevis J.P.L. Pelseneer, 1903 - (PHILOBRYIDAE)
- orbiculata, Pleurodonte orbiculata A.E.J. Férussac, 1821 - (PLEURODONTIDAE)
- orbiculata, Indonellina orbiculata Silantiev, Chandra & Urazaeva, 2015 † - (PROKOPIEVSKIIDAE) (FOSSIL)
- orbiculata, Scrobicularia orbiculata L. Spengler, 1793 - syn of: Scrobicularia plana (E.M. Da Costa, 1778) - (SCROBICULARIIDAE)
- orbiculata, Semele orbiculata T. Say, 1822 - syn of: Semele proficua (R. Pulteney, 1799) - (SEMELIDAE)
- orbiculata, Streblochondria orbiculata C.O. Waterhouse, 1982 † - (STREBLOCHONDRIIDAE) (FOSSIL)
- orbiculata, Tellina orbiculata S.A. Renier - syn of: Arcopagia balaustina (C. Linnaeus, 1758) - (TELLINIDAE)
- orbiculata, Axinopsida orbiculata (G.O. Sars, 1878) - (THYASIRIDAE)
- orbiculata, Thyasira orbiculata G. Seguenza, 1876 - syn of: Parathyasira granulosa (T.A. de M. Monterosato, 1874) - (THYASIRIDAE)
- orbiculata, Malea orbiculata (G.B. Brocchi, 1814 †) - (TONNIDAE) (FOSSIL)
- orbiculata, Stomatella orbiculata A. Adams, 1850 - (TROCHIDAE)
- orbiculata, Diplodonta orbiculata É.A.A. Locard, 1898 - syn of: Diplodonta brocchii (G.P. Deshayes, 1850) - (UNGULINIDAE)
- orbiculata, Lamellaria orbiculata W.H. Dall, 1871 - (VELUTINIDAE)
- orbiculata, Pitar orbiculata Berezovsky, 2010 † - (VENERIDAE) (FOSSIL)
- orbiculata, Dosinia orbiculata R.W. Dunker, 1877 - (VENERIDAE)
- orbiculata, Venus orbiculata G. Montagu, 1808 - syn of: Ctena orbiculata (G. Montagu, 1808) - (VENERIDAE)
- orbiculata, Dosinia orbiculata T. Brown, 1827 - syn of: Dosinia exoleta (C. Linnaeus, 1758) - (VENERIDAE)
- orbiculata filiata, Ctena orbiculata filiata W.H. Dall, 1901 - (LUCINIDAE)
- orbiculata inaegualis, Axinopsida orbiculata inaegualis (G.O. Sars, 1878) - (THYASIRIDAE)
- orbiculata inaequalis, Axinopsida orbiculata inaequalis A.E. Verrill & K.J. Bush, 1898 - syn of: Axinopsida serricata (P.P. Carpenter, 1864) - (THYASIRIDAE)
- orbiculata inequalis, Axinopsida orbiculata inequalis A.E. Verrill & K.J. Bush, 1898 - syn of: Axinopsida serricata (P.P. Carpenter, 1864) - (THYASIRIDAE)
- orbiculata miocaenica, Malea orbiculata miocaenica A.E.M. Cossmann & M.A. Peyrot, 1921 - (TONNIDAE)
- orbiculata recurvata, Ctena orbiculata recurvata W.H. Dall, 1901 - (LUCINIDAE)
- orbiculata tropica, Olygyra orbiculata tropica L. Pfeiffer, 1852 - (HELICINIDAE)
- orbiculatum, Borissiakoceras orbiculatum L.W. Stephenson, 1955 † - (BINNEYITIDAE) (FOSSIL)
- orbiculatum, Parvamussium orbiculatum H.H. Dijkstra & P. Maestrati, 2013 - (PROPEAMUSSIIDAE)
- orbiculatummiocaenicum, Malea orbiculatummiocaenicum A.E.M. Cossmann & M.A. Peyrot, 1921 - (TONNIDAE)
- orbiculatus, Paradanubites orbiculatus Shevyrev, 1968 † - (DANUBITIDAE) (FOSSIL)
- orbiculatus, Stilifer orbiculatus C. Hedley, 1907 - syn of: Fossarella orbiculatus (C. Hedley, 1907) - (EULIMIDAE)
- orbiculatus, Arctonautilus orbiculatus E.S. Sobolev, 1989 † - (PROPTYCHITIDAE) (FOSSIL)
- orbiculatus, Unio orbiculatus S.P. Hildreth, 1828 - syn of: Lampsilis abrupta T. Say, 1831 - (UNIONIDAE)
- orbiculatus, Fossarella orbiculatus (C. Hedley, 1907) - (VANIKORIDAE)
- Orbiculopecten, Genus Orbiculopecten Gonzalez, 1978 (PTERIIDA (unassigned)) (FOSSIL)
- orbiculum, Ammonites orbiculum A.H.E. Beyrich, 1837 † - syn of: Sphaeromanticoceras orbiculum (A.H.E. Beyrich, 1837 †) - (AMMONITIDA (unassigned)) (FOSSIL)
- orbiculum, Sphaeromanticoceras orbiculum (A.H.E. Beyrich, 1837 †) - (GEPHUROCERATIDAE) (FOSSIL)
- orbiculus, Myloceras orbiculus Whitehouse, 1926 † - (LABECERATIDAE) (FOSSIL)
- orbiculus, Scaphander orbiculus F.E. Edwards † - (SCAPHANDRIDAE) (FOSSIL)
- orbiculus, Temnodiscus orbiculus (Lindström, 1884 †) - (TROPIDODISCIDAE) (FOSSIL)
- Orbiculus, syn of: Genus Dosinia J.A. Scopoli, 1777 (VENERIDAE)
- orbiculus dunkeri, Tropicorbis orbiculus dunkeri H.B. Baker, 1945 - syn of: Biomphalaria orbicula (P.M.A. Morelet, 1849) - (PLANORBIDAE)
- orbigneyi, Arhecharax orbigneyi (C.M.F. Ancey) - (PROSERPINELLIDAE)
- orbigniana, Sepia orbigniana A.E.J. Férussac, 1826 - syn of: Sepia orbignyana A.E.J. Férussac, 1826 - (SEPIIDAE)
- orbignianus, Murex orbignianus A. Risso, 1826 - syn of: Ocenebra erinaceus (C. Linnaeus, 1758) - (MURICIDAE)
- orbignii, Diacrolinia orbignii (P.C.A.S.L. Rang, 1827 †) - (CAVOLINIIDAE) (FOSSIL)
- orbignii, Doto orbignii (A.E.J. Férussac, 1822) - (DOTIDAE)
- orbignii, Xerotricha orbignii (D'Orbigny, 1836) - (HYGROMIIDAE)
- orbigny, Monilearia orbigny (D'Orbigny, 1839) - (COCHLICELLIDAE)
- orbigny, Haliotis orbigny O.G. Costa, 1838 - syn of: Scissurella costata d'Orbigny, 1824 - (HALIOTIDAE)
- orbigny, Biradiolites orbigny Toucas, 1940 † - syn of: Biradiolites lameracensis Toucas, 1909 † - (RADIOLITIDAE) (FOSSIL)
- orbigny, Osteodesma orbigny P. Fischer, 1857 - syn of: Entodesma brasiliense (A.A. Gould, 1850) - (THRACIIDAE)
- Orbignya, Genus Orbignya Fischer, 1887 (HIPPURITIDAE) (FOSSIL)
- orbignyana, Bulla orbignyana A.E.J. Férussac, 1822 - syn of: Haminoea orbignyana (A.E.J. Férussac, 1822) - (BULLIDAE)
- orbignyana, Loxacypraea orbignyana (J.P.S. Grateloup, 1846 †) - (CYPRAEIDAE) (FOSSIL)
- orbignyana, Sabinella orbignyana (L.H. Hupé, 1860) - (EULIMIDAE)
- orbignyana, Devonorhineoderma orbignyana (d'Archiac & de Verneuil, 1842 †) - (GOSSELETINIDAE) (FOSSIL)
- orbignyana, Haminoea orbignyana (A.E.J. Férussac, 1822) - (HAMINOEIDAE)
- orbignyana, Castalia orbignyana L. Deville & L.H. Hupé, 1850 - syn of: Castalia orbignyi (L. Deville & L.H. Hupé, 1850) - (HYRIIDAE)
- orbignyana, Mesomiltha orbignyana (d'Archiac, 1843 †) - (LUCINIDAE) (FOSSIL)
- orbignyana, Medlicottia orbignyana (de Verneuil, 1845 †) - (MEDLICOTTIIDAE) (FOSSIL)
- orbignyana, Coralliophila erosa orbignyana (S.A.A. Petit De La Saussaye, 1851) - (MURICIDAE)
- orbignyana, Monocondylaea orbignyana M. Doello-Jurado, 1917 - syn of: Monocondylaea paraguayana D'Orbigny, 1835 - (MYCETOPODIDAE)
- orbignyana, Nerita orbignyana C.A. Récluz, 1841 - (NERITIDAE)
- orbignyana, Patella orbignyana F. Nordsieck & F.F. Talavera, 1979 - syn of: Patella ulyssiponensis J.F. Gmelin, 1791 - (PATELLIDAE)
- orbignyana, Cyrtopleura orbignyana (Leves in Graves, 1847 †) - (PHOLADIDAE) (FOSSIL)
- orbignyana, Pleurotomaria orbignyana d'Archiac & de Verneuil, 1842 † - syn of: Devonorhineoderma orbignyana (d'Archiac & de Verneuil, 1842 †) - (PLEUROTOMARIIDAE) (FOSSIL)
- orbignyana, Purpurina orbignyana Hebert & Deslongchamps, 1860 † - (PURPURINIDAE) (FOSSIL)
- orbignyana, Sepia orbignyana A.E.J. Férussac, 1826 - (SEPIIDAE)
- orbignyana, Tegula orbignyana H.A. Pilsbry, 1900 - (TEGULIDAE)
- orbignyana, Vanikoro orbignyana (C.A. Récluz, 1844) - (VANIKORIDAE)
- orbignyana colligens, Loxacypraea orbignyana colligens F. Sacco, 1894 † - syn of: Loxacypraea colligens (F. Sacco, 1894 †) - (CYPRAEIDAE) (FOSSIL)
- orbignyanum, Placenticeras orbignyanum (H.B. Geinitz, 1849 †) - (PLACENTICERATIDAE) (FOSSIL)
- orbignyanum, Chondroceras orbignyanum (T. Wright, 1859 †) - (SPHAEROCERATIDAE) (FOSSIL)
- orbignyanus, Navanax orbignyanus (A. de Rochebrune, 1881) - (AGLAJIDAE)
- orbignyanus, Posterobranchus orbignyanus A. de Rochebrune, 1881 - syn of: Navanax orbignyanus (A. de Rochebrune, 1881) - (AGLAJIDAE)
- orbignyanus, Ammonites orbignyanus H.B. Geinitz, 1849 † - syn of: Placenticeras orbignyanum (H.B. Geinitz, 1849 †) - (AMMONITIDA (unassigned)) (FOSSIL)
- orbignyanus, Ambercyclus orbignyanus (Hudleston, 1893 †) - (EUCYCLIDAE) (FOSSIL)
- orbignyanus, Euphemites orbignyanus (Portlock, 1843 †) - (EUPHEMITIDAE) (FOSSIL)
- orbignyanus, Fusus orbignyanus Münster, 1841 † - syn of: Macrochilina orbignyi (Münster, 1841 †) - (FASCIOLARIIDAE) (FOSSIL)
- orbignyanus, Goniatites orbignyanus de Verneuil, 1845 † - syn of: Medlicottia orbignyana (de Verneuil, 1845 †) - (GONIATITIDAE) (FOSSIL)
- orbignyanus, Murex orbignyanus A. Risso, 1826 - syn of: Ocenebra erinaceus (C. Linnaeus, 1758) - (MURICIDAE)
- orbignyanus, Mytilus orbignyanus L.H. Hupé in C. Gay, 1854 - syn of: Aulacomya atra (J.I. Molina, 1782) - (MYTILIDAE)
- orbignyanus, Turbo orbignyanus d'Archiac & de Verneuil, 1842 † - syn of: Devonorhineoderma orbignyana (d'Archiac & de Verneuil, 1842 †) - (TURBINIDAE) (FOSSIL)
- Orbignyceras, Genus Orbignyceras Gerard & Contaut, 1936 (OPPELIIDAE) (FOSSIL)
- orbignyi, Acmaea orbignyi W.H. Dall, 1909 - syn of: Lottia orbignyi (W.H. Dall, 1909) - (ACMAEIDAE)
- orbignyi, Hysteroceras orbignyi Spath, 1922 † - (BRANCOCERATIDAE) (FOSSIL)
- orbignyi, Naesiotus orbignyi (L. Pfeiffer, 1846) - (BULIMULIDAE)
- orbignyi, Cavolinia orbignyi L.F.A. Souleyet, 1852 - syn of: Diacria quadridentata (H.M.D. de Blainville, 1821) - (CAVOLINIIDAE)
- orbignyi, Columbinia orbignyi (C.M.F. Ancey, 1892) - (CLAUSILIIDAE)
- orbignyi, Bathyconus orbignyi (J.V. Audouin, 1831) - (CONIDAE)
- orbignyi, Discodoris orbignyi H. Adams & A. Adams, 1858 - syn of: Montereina punctifera (F.D. Abraham, 1877) - (DISCODORIDIDAE)
- orbignyi, Doris orbignyi H. Adams & A. Adams, 1858 - syn of: Montereina punctifera (F.D. Abraham, 1877) - (DORIDIDAE)
- orbignyi, Douvilleiceras orbignyi A. Hyatt, 1903 † - (DOUVILLEICERATIDAE) (FOSSIL)
- orbignyi, Epitonium orbignyi P. Nyst, 1871 - syn of: Epitonium georgettinum L.C. Kiener, 1838 - (EPITONIIDAE)
- orbignyi, Phlyseogrammoceras orbignyi (Buckman) † - (HILDOCERATIDAE) (FOSSIL)
- orbignyi, Castalia orbignyi (L. Deville & L.H. Hupé, 1850) - (HYRIIDAE)
- orbignyi, Janthina orbignyi O.A.L. Mörch, 1860 - syn of: Janthina janthina (C. Linnaeus, 1758) - (JANTHINIDAE)
- orbignyi, Limaria orbignyi (É. Lamy, 1930) - (LIMIDAE)
- orbignyi, Oistoceras orbignyi Spath, 1938 † - (LIPAROCERATIDAE) (FOSSIL)
- orbignyi, Potamolithus orbignyi H.A. Pilsbry, 1896 - (LITHOGLYPHIDAE)
- orbignyi, Lottia orbignyi (W.H. Dall, 1909) - (LOTTIIDAE)
- orbignyi, Farcimoides orbignyi (L. Pfeiffer, 1851) - (MEGALOMASTOMIDAE)
- orbignyi, Trophon orbignyi A. Carcelles, 1946 - syn of: Trophon pelseneeri E.A. Smith, 1915 - (MURICIDAE)
- orbignyi, Mycetopoda orbignyi H.F.A. von Ihering, 1910 - syn of: Mycetopoda siliquosa (J.B. von Spix, 1827) - (MYCETOPODIDAE)
- orbignyi, Olivancillaria orbignyi (F.P. Marrat, 1868) - (OLIVIDAE)
- orbignyi, Normannites orbignyi (Buckman, 1908 †) - (OTOITIDAE) (FOSSIL)
- orbignyi, Phymatoceras orbignyi Gabilly, 1976 † - (PHYMATOCERATIDAE) (FOSSIL)
- orbignyi, Fossarus orbignyi P. Fischer, 1864 - (PLANAXIDAE)
- orbignyi, Fossarus orbignyi G.W. Nowell-Usticke, 1959 - syn of: Fossarus ambiguus (C. Linnaeus, 1758) - (PLANAXIDAE)
- orbignyi, Biomphalaria orbignyi W.L. Paraense, 1975 - (PLANORBIDAE)
- orbignyi, Alvania orbignyi J.V. Audouin, 1826 - syn of: Alvania dorbignyi (J.V. Audouin, 1826) - (RISSOIDAE)
- orbignyi, Rissoina orbignyi A. Adams, 1851 - syn of: Rissoina dorbignyi A. Adams, 1851 - (RISSOINIDAE)
- orbignyi, Macrochilina orbignyi (Münster, 1841 †) - (SOLENISCIDAE) (FOSSIL)
- orbignyi, Spiroceras orbignyi (Baugier & Sauzé, 1843 †) - (SPIROCERATIDAE) (FOSSIL)
- orbignyi, Cadomites orbignyi de Grossouvre, 1930 † - (STEPHANOCERATIDAE) (FOSSIL)
- orbignyi, Circulus orbignyi (P. Fischer, 1857) - (TORNIDAE)
- orbignyi, Unio orbignyi L. Deville & L.H. Hupé, 1850 - syn of: Castalia orbignyi (L. Deville & L.H. Hupé, 1850) - (UNIONIDAE)
- orbignyi, Dosinia orbignyi R.W. Dunker, 1845 - (VENERIDAE)
- orbignyi aratus, Conus orbignyi aratus R.N. Kilburn, 1973 - syn of: Conasprella elokismenos (R.N. Kilburn, 1975) - (CONIDAE)
- orbignyi coriolisi, Conus orbignyi coriolisi D. Röckel, G. Richard & R.G. Moolenbeek, 1995 - syn of: Bathyconus coriolisi (G. Richard & R.G. Moolenbeek, 1995) - (CONIDAE)
- orbignyi elokismenos, Conus orbignyi elokismenos R.N. Kilburn, 1975 - syn of: Conasprella elokismenos (R.N. Kilburn, 1975) - (CONIDAE)
- orbignyi pachylabris, Rissoina orbignyi pachylabris G. Nevill, 1884 - syn of: Rissoina dorbignyi A. Adams, 1851 - (RISSOINIDAE)
- orbignyi submarginata, Rissoina orbignyi submarginata G. Nevill, 1884 - syn of: Rissoina dorbignyi A. Adams, 1851 - (RISSOINIDAE)
- orbignyi subspirata, Rissoina orbignyi subspirata G. Nevill, 1884 - syn of: Rissoina dorbignyi A. Adams, 1851 - (RISSOINIDAE)
- Orbignyia, syn of: Genus Cavolinia P.C. Abildgaard, 1791 (CAVOLINIIDAE)
- Orbignyiceras, Genus Orbignyiceras Royo & Gomez, 1945 (LEPTOCERATOIDIDAE) (FOSSIL)
- Orbignytesta, Subgenus Olivella (Orbignytesta) M.A. Klappenbach, 1962 (OLIVELLIDAE)
- Orbigonina, Genus Orbigonina M.R. Cooper, 2015 (PTEROTRIGONIIDAE) (FOSSIL)
- orbilobatus, Xiangulingites orbilobatus J.K. Zhao & al., 1978 † - (ANDERSSONOCERATIDAE) (FOSSIL)
- orbirugata, Aphanaia orbirugata Harrington, 1955 † - (ATOMODESMATIDAE) (FOSSIL)
- orbis, Stenarcestes orbis (Mojsisovics, 1875 †) - (ARCESTIDAE) (FOSSIL)
- Orbis, syn of: Genus Acanthocardia J.E. Gray, 1851 (CARDIIDAE)
- orbis, Discohelix orbis A.E. Reuss, 1852 † - (DISCOHELICIDAE) (FOSSIL)
- orbis, Theba orbis J.G. Hidalgo, 1875 - syn of: Theba pisana (O.F. Müller, 1774) - (HELICIDAE)
- orbis, Oxycerites orbis (Giebel, 1852 †) - (OPPELIIDAE) (FOSSIL)
- orbis, Pluripharciceras orbis Bockwinkel, Becker & Ebbighausen, 2013 † - (PHARCICERATIDAE) (FOSSIL)
- orbis, Cyclostremella orbis (P.P. Carpenter, 1857) - (PYRAMIDELLIDAE)
- orbis, Trocholites orbis Schroeder, 1891 † - (TROCHOLITIDAE) (FOSSIL)
- orbita, Aenator orbita A.N. Golikov & B.I. Sirenko, 1988 - syn of: Aeneator recens (R.K. Dell, 1951) - (BUCCINIDAE)
- orbita, Vasticardium orbita (L.A. Reeve, 1845) - (CARDIIDAE)
- orbita, Cardium orbita L.A. Reeve, 1845 - syn of: Vasticardium orbita (L.A. Reeve, 1845) - (CARDIIDAE)
- orbita, Trachycardium orbita W.J. Broderip & G.B. I Sowerby, 1833 - syn of: Vasticardium orbita (L.A. Reeve, 1845) - (CARDIIDAE)
- orbita, Acrosterigma orbita W.H. Dall, P. Bartsch & H.A. Rehder, 1939 - syn of: Vasticardium hawaiensis W.H. Dall, P. Bartsch & H.A. Rehder, 1939 - (CARDIIDAE)
- orbita, Dicathais orbita (J.F. Gmelin, 1791) - (MURICIDAE)
- orbita, Caperella orbita (C. Hedley, 1900) - (TORNIDAE)
- orbita, Trochotoma orbita Pan, 1982 † - (TROCHOTOMIDAE) (FOSSIL)
- orbita aegrota, Dicathais orbita aegrota (L.A. Reeve, 1846) - (MURICIDAE)
- orbita hawaiensis, Vasticardium orbita hawaiensis W.H. Dall, P. Bartsch & H.A. Rehder, 1939 - syn of: Vasticardium hawaiensis W.H. Dall, P. Bartsch & H.A. Rehder, 1939 - (CARDIIDAE)
- orbita textilosa, Dicathais orbita textilosa (J.B.P.A. Lamarck, 1822) - (MURICIDAE)
- orbitatus, Conus orbitatus L.A. Reeve, 1843 - syn of: Asprella sulcata (C.H. Hwass in J.G. Bruguière, 1792) - (CONIDAE)
- Orbitestella, Genus Orbitestella T. Iredale, 1917 (ORBITESTELLIDAE)
- ORBITESTELLIDAE Iredale, 1917 - Family (GASTROPODA-HETEROBRANCHIA-HETEROSTROPHA)
- Orbitina, syn of: Genus Rumina A. Risso, 1826 (SUBULINIDAE)
- Orbitophora, syn of: Genus Viriola F.P. Jousseaume, 1884 (TRIPHORIDAE)
- orbitosus, Sakhaites orbitosus Vozin, 1972 † - syn of: Sakhaites vronskyi (A.M. Popov, 1961 †) - (OPHICERATIDAE) (FOSSIL)
- Orbitriphora, syn of: Genus Viriola F.P. Jousseaume, 1884 (TRIPHORIDAE)
- orbitula, Helicostyla orbitula G.B. I Sowerby, 1841 - (BRADYBAENIDAE)
- orbitus, Aeneator orbitus (F.W. Hutton, 1885 †) - (BUCCINIDAE) (FOSSIL)
- orbnutus, Cadulus orbnutus (T.A. Conrad, 1869 †) - (GADILIDAE) (FOSSIL)
- Orbobactrites, Genus Orbobactrites Mapes, 1979 (PARABACTRITIDAE) (FOSSIL)
- Orbonella, syn of: Genus Obornella Cox, 1959 (PLEUROTOMARIIDAE) (FOSSIL)
- orbus, Edouardia orbus (W.T. Blanford) - (CERASTUIDAE)
- orbus, Unio orbus É.A.A. Locard, 1889 - syn of: Unio arcuatus N.R. Bouchard-Chantereaux, 1838 - (UNIONIDAE)
- orbygnyana, Rhombosepion orbygnyana (A.E.J. Férussac, 1826) - (SEPIIDAE)
- orbygnyi, Castaliella sulcata orbygnyi (L.H. Hupé & L. Deville, 1850) - (HYRIIDAE)
- orca, Philine orca T.M. Gosliner, 1988 - (PHILINIDAE)
- orca, Ericusa orca B.C. Cotton, 1952 - syn of: Ericusa fulgetrum orca (B.C. Cotton, 1952) - (VOLUTIDAE)
- orca, Ericusa fulgetrum orca (B.C. Cotton, 1952) - (VOLUTIDAE)
- orcadensis, Bathyberthella orcadensis F.J. García, J.C. García-Gómez, J.S. Troncoso & J.L. Cervera, 1994 - (PLEUROBRANCHIDAE)
- orcadis, Montidelos orcadis (T. Iredale, 1943) - (RHYTIDIDAE)
- orcas, Amphicyrtoceras orcas (J.W. Hall †) - (ACLEISTOCERATIDAE) (FOSSIL)
- orcasense, Pisidium orcasense V. Sterki, 1922 - syn of: Pisidium casertanum (Poli, 1791) - (SPHAERIIDAE)
- orcesi, Drymaeus expansus orcesi W.K. Weyrauch, 1958 - (BULIMULIDAE)
- orcesi, Thaumastus orcesi W.K. Weyrauch, 1967 - (MEGASPIRIDAE)
- Orcesiellus, syn of: Subgenus Plekocheilus (Aeropictus) W.K. Weyrauch, 1967 (AMPHIBULIMIDAE)
- orcha, Doto orcha N. Yonow, 2000 - (DOTIDAE)
- orchardi, Caucasites orchardi Bucher, 2002 † - (GYMNITIDAE) (FOSSIL)
- orchardi, Dryojuvavites orchardi Tozer, 1994 † - (JUVAVITIDAE) (FOSSIL)
- orchardi, Nuetzelopsis orchardi Frýda & al., 2003 † - (NERITOPSIDAE) (FOSSIL)
- orchida, Gulella orchida K.C. Emberton, 2001 - (STREPTAXIDAE)
- orchidae, Owensgriffithsius orchidae K.C. Emberton, 2002 - (CYCLOPHORIDAE)
- orchidae, Cyclotopsis orchidae (K.C. Emberton, 2003) - (POMATIIDAE)
- orchidaea, Chelidonura orchidaea A. Perrone, 1990 - (AGLAJIDAE)
- orchidifloris, Murex orchidifloris T. Shikama, 1973 - syn of: Chicoreus orchidiflorus (T. Shikama, 1973) - (MURICIDAE)
- orchidiflorus, Chicoreus orchidiflorus (T. Shikama, 1973) - (MURICIDAE)
- orchidiflorus, Pterynotus orchidiflorus T. Shikama, 1973 - syn of: Chicoreus orchidiflorus (T. Shikama, 1973) - (MURICIDAE)
- orchidiflorus celinamarumai, Latiaxis orchidiflorus celinamarumai (S. Kosuge, 1980) - syn of: Latiaxis cerinamarumai (S. Kosuge, 1980) - (MURICIDAE)
- orchidus, Kalidos orchidus K.C. Emberton, 2007 - (ARIOPHANTIDAE)
- orchis, Sitala orchis H.H. Godwin-Austen, 1891 - (ARIOPHANTIDAE)
- orcia, Yoldiella orcia (W.H. Dall, 1916) - (YOLDIIDAE)
- orcina, Lyncina vitellus orcina T. Iredale, 1931 - (CYPRAEIDAE)
- orcula, Bithynia orcula G.R. von Frauenfeld, 1862 - (BITHYNIIDAE)
- orcula, Helix orcula W.H. Benson, 1850 - syn of: Pupisoma orcula (W.H. Benson, 1850) - (HELICIDAE)
- Orcula, Genus Orcula F. Held, 1837 (ORCULIDAE)
- orcula, Microlampra orcula Pan & Erwin, 2002 † - (ORTHONEMIDAE) (FOSSIL)
- orcula, Pupisoma orcula (W.H. Benson, 1850) - (VERTIGINIDAE)
- Orculella, Genus Orculella C.M. Steenberg, 1925 (ORCULIDAE)
- ORCULIDAE Steenberg, 1925 - Family (GASTROPODA-HETEROBRANCHIA-PULMONATA-STYLOMMATOPHORA)
- orcutti, Amnicola orcutti H.A. Pilsbry, 1928 - syn of: Littoridina orcutti (H.A. Pilsbry, 1928) - (AMNICOLIDAE)
- orcutti, Barleeia orcutti P. Bartsch, 1920 - (BARLEEIIDAE)
- orcutti, Caecum orcutti W.H. Dall, 1885 - (CAECIDAE)
- orcutti, Littoridina orcutti (H.A. Pilsbry, 1928) - (COCHLIOPIDAE)
- orcutti, Epiphragmophora orcutti W.H. Dall, 1900 - (EPIPHRAGMOPHORIDAE)
- orcutti, Fusinus orcutti W.H. Dall, 1915 - syn of: Trachypollia lugubris (C.B. Adams, 1852) - (FASCIOLARIIDAE)
- orcutti, Chlamydoconcha orcutti W.H. Dall, 1884 - (GALEOMMATIDAE)
- orcutti, Lima orcutti L.G. Hertlein & J. Grant, 1972 - syn of: Limaria orbignyi (É. Lamy, 1930) - (LIMIDAE)
- orcutti, Mitra orcutti W.H. Dall, 1920 - syn of: Mitromorpha orcutti (W.H. Dall, 1920) - (MITRIDAE)
- orcutti, Mitromorpha orcutti (W.H. Dall, 1920) - (MITROMORPHIDAE)
- orcutti, Amicula orcutti W.H. Dall, 1884 - (MOPALIIDAE)
- orcutti, Poteria orcutti P. Bartsch, 1942 - (NEOCYCLOTIDAE)
- orcutti, Nuculana orcutti R. Arnold, 1907 † - (NUCULANIDAE) (FOSSIL)
- orcutti, Weinlandipoma orcutti (P. Bartsch, 1946) - (POMATIIDAE)
- orcutti, Sanguinolaria orcutti W.H. Dall, 1921 - syn of: Nuttallia nuttallii (T.A. Conrad, 1837) - (PSAMMOBIIDAE)
- orcutti, Nuttallia orcutti W.H. Dall, 1921 - syn of: Nuttallia nuttallii (T.A. Conrad, 1837) - (PSAMMOBIIDAE)
- orcutti, Macron orcutti W.H. Dall, 1918 - (PSEUDOLIVIDAE)
- orcutti, Bankia orcutti P. Bartsch, 1923 - (TEREDINIDAE)
- orcutti, Holospira orcutti P. Bartsch, 1925 - (UROCOPTIDAE)
- orcutti, Anisospira orcutti W.H. Dall, 1910 - syn of: Anisospira liebmanni (L. Pfeiffer, 1846) - (UROCOPTIDAE)
- orcutti, Macrocallista orcutti W.H. Dall, 1918 - syn of: Megapitaria squalida (G.B. I Sowerby, 1835) - (VENERIDAE)
- orcuttiana, Coralliophila orcuttiana W.H. Dall, 1919 - (MURICIDAE)
- orcuttianum, Epitonium orcuttianum W.H. Dall, 1917 - syn of: Epitonium californicum W.H. Dall, 1917 - (EPITONIIDAE)
- orcuttii, Unio orcuttii B.H. Wright, 1888 - syn of: Elliptio jayensis I. Lea, 1838 - (UNIONIDAE)
- Orcuttipoma, syn of: Genus Rhytidopoma E.R. Sykes, 1901 (POMATIIDAE)
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