- sema, Charopinesta sema T. Iredale, 1944 - (CHAROPIDAE)
- Semahana, Genus Semahana Martin, 1931 † (NEOGASTROPODA (UNASSIGNED)) (FOSSIL)
- Semailia, Genus Semailia Morris & Skelton, 1995 † (TRECHMANNELLIDAE) (FOSSIL)
- semari, Rissoina semari C. Beets, 1941 † - (RISSOINIDAE) (FOSSIL)
- sematana, Anomia sematana M. Yokoyama, 1922 - syn of: Isomonia umbonata (A.A. Gould, 1861) - (ANOMIIDAE)
- sematana, Turbonilla sematana M. Yokoyama, 1922 - (PYRAMIDELLIDAE)
- sematana, Parvithracia sematana (M. Yokoyama, 1922) - (THRACIIDAE)
- sematensis, Potamocorbula sematensis M. Yokoyama, 1922 - syn of: Potamocorbula amurensis (L. von Schrenck, 1861) - (CORBULIDAE)
- sematensis, Saccella sematensis (M. Suzuki & Ishizuka, 1943) - (NUCULANIDAE)
- sematensis, Conotalopia sematensis (K. Oyama, 1942) - (TROCHIDAE)
- semeion, Glossodoris semeion R. Winckworth, 1946 - (CHROMODORIDIDAE)
- semela, Turbonilla semela P. Bartsch, 1924 - (PYRAMIDELLIDAE)
- Semelangulus, Genus Semelangulus T. Iredale, 1924 (TELLINIDAE)
- Semelartemis, syn of: Genus Dosinia J.A. Scopoli, 1777 (VENERIDAE)
- semele, Platydoris semele H.M.D. de Blainville - syn of: Platydoris scabra (G.L.C.F.D. Cuvier, 1804) - (DISCODORIDIDAE)
- semele, Isimerope semele C. Radea & A. Parmakelis, 2013 - (HYDROBIIDAE)
- semele, Rochefortia semele W.H. Dall, 1924 - syn of: Rochefortina sandwichensis (E.A. Smith, 1885) - (LASAEIDAE)
- semele, Plethospira semele J.W. Hall, 1861 † - syn of: Brachytomaria semele (J.W. Hall, 1861 †) - (MURCHISONIIDAE) (FOSSIL)
- semele, Brachytomaria semele (J.W. Hall, 1861 †) - (PHANEROTREMATIDAE) (FOSSIL)
- Semele, Genus Semele H.C.F. Schumacher, 1817 (SEMELIDAE)
- semele, Ervilia semele W.H. Dall, 1924 - syn of: Rochefortina sandwichensis (E.A. Smith, 1885) - (SEMELIDAE)
- SEMELIDAE Stoliczka, 1870 (1825) - Family (BIVALVIA-HETERODONTA [Subclass]-EUHETERODONTA [Infraclass]-IMPARIDENTIA [Superorder]-VENERIDA [Order]-TELLINOIDEA [Superfamily])
- semeliformis, Semelilucina semeliformis R. von Cosel & P. Bouchet, 2008 - (LUCINIDAE)
- Semelilucina, Genus Semelilucina R. von Cosel & P. Bouchet, 2008 (LUCINIDAE)
- Semelina, Genus Semelina W.H. Dall, 1900 (SEMELIDAE)
- Semeloidea, Genus Semeloidea Bartrum & Powell, 1928 † (LASAEIDAE) (FOSSIL)
- Semelucina, syn of: Genus Semelilucina R. von Cosel & P. Bouchet, 2008 (LUCINIDAE)
- semen, Acteon semen E. Forbes, 1846 - (ACTEONIDAE)
- semen, Amphithalamus semen (N.H. Odhner, 1924) - (ANABATHRIDAE)
- semen, Chavanella semen (Cossmann 1908) † - (CARDIIDA (UNASSIGNED)) (FOSSIL)
- semen, Carditella semen (L.A. Reeve, 1843) - (CONDYLOCARDIIDAE)
- semen, Carditella semen L.A. Reeve, 1843 - syn of: Carditella semen (L.A. Reeve, 1843) - (CONDYLOCARDIIDAE)
- semen, Cypraea semen Cooke, 1919 † - (CYPRAEIDAE) (FOSSIL)
- semen, Arthritica semen (K.T. Menke, 1843) - (LASAEIDAE)
- semen, Mangelia semen L.A. Reeve, 1846 - (MANGELIIDAE)
- semen, Bullata semen (Lea, 1833 †) - (MARGINELLIDAE) (FOSSIL)
- semen, Mitra semen L.A. Reeve, 1845 - syn of: Vexillum zebrinum (A.V.M.D. D'Orbigny, 1840) - (MITRIDAE)
- semen, Gregariella semen J.B.P.A. Lamarck, 1819 - syn of: Gregariella coralliophaga (J.F. Gmelin, 1791) - (MYTILIDAE)
- semen, Modiolus semen J.B.P.A. Lamarck, 1819 - syn of: Gregariella coralliophaga (J.F. Gmelin, 1791) - (MYTILIDAE)
- semen, Neritina semen C.M. Tapparone-Canefri, 1875 - syn of: Smaragdia souverbiana (R.P. Montrouzier, 1863) - (NERITIDAE)
- semen, Calorhadia semen (Lea, 1883 †) - (NUCULANIDAE) (FOSSIL)
- semen, Nuculana semen E.A. Smith, 1885 - syn of: Ledella parva A.E. Verrill & K.J. Bush, 1897 - (NUCULANIDAE)
- semen, Nucula semen K.H.J. Thiele & S.G.A. Jaeckel, 1931 - (NUCULIDAE)
- semen, Simnia semen (J.L.M. Defrance, 1825 †) - (OVULIDAE) (FOSSIL)
- semen, Eulimella semen A. Peñas & E. Rolán, 2016 - (PYRAMIDELLIDAE)
- semen, Retusa semen (L.A. Reeve, 1855) - (RETUSIDAE)
- semen, Retusa semen K.H.J. Thiele, 1925 - syn of: Pyrunculus pyriformis (A. Adams, 1850) - (RETUSIDAE)
- semen, Cadella semen (S.C.T. Hanley, 1845) - (TELLINIDAE)
- semen, Tellina semen S.C.T. Hanley, 1845 - syn of: Cadella semen (S.C.T. Hanley, 1845) - (TELLINIDAE)
- semenformis, Perheida semenformis A. Peñas & E. Rolán, 2017 † - (PYRAMIDELLIDAE) (FOSSIL)
- semenkewitschi, Baicalia semenkewitschi C. Lidholm, 1909 - (AMNICOLIDAE)
- semenkewitschi nitida, Baicalia semenkewitschi nitida (Kozhov, 1936) - (AMNICOLIDAE)
- semenline, Habroconus semenline S. Moricand, 1845 - syn of: Habroconus semenlini (S. Moricand, 1845) - (EUCONULIDAE)
- semenlini, Habroconus semenlini (S. Moricand, 1845) - (EUCONULIDAE)
- semenlini, Pseudoguppya semenlini S. Moricand, 1845 - syn of: Habroconus semenlini (S. Moricand, 1845) - (EUCONULIDAE)
- semenovi, Ponsadenia semenovi (E.C. Von Martens, 1864) - (BRADYBAENIDAE)
- semenovi, Buliminus semenovi C.M.F. Ancey, 1893 - syn of: Pseudonapaeus secalinus (E.C. Von Martens, 1881) - (ENIDAE)
- semenovi, Multidentata semenovi (Pronina, 1980 †) - (NUCULANIDAE) (FOSSIL)
- semenovi, Parussuria semenovi Zakharov, 1968 † - syn of: Parussuria compressa (A. Hyatt & Smith, 1905 †) - (USSURIIDAE) (FOSSIL)
- Semenoviceras, Genus Semenoviceras Wright , 1960 † (HOPLITIDAE) (FOSSIL)
- Semenovites, Genus Semenovites Glazunova, 1960 † (HOPLITIDAE) (FOSSIL)
- Sementiconcha, Genus Sementiconcha Hautmann & al., 2013 † (MYOPHORICARDIIDAE) (FOSSIL)
- sementis, Gibbula sementis E. Rolán & J. Templado, 2001 - (TROCHIDAE)
- semfala, Lophiotoma semfala Puillandre, Fedosov, Zaharias, Azanar-Cormano & Kantor, 2017 - (TURRIDAE)
- Semiactaeon, Subgenus Acteon (Semiactaeon) A.E.M. Cossmann, 1889 (ACTEONIDAE)
- semiacuticostata, Lyria semiacuticostata (G.B. Pritchard, 1896 †) - (VOLUTIDAE) (FOSSIL)
- semialatus, Physunio semialatus (G.P. Deshayes & A. Jullien, 1874) - (UNIONIDAE)
- semiannulatum, Hemicosmorthoceras semiannulatum (Barrande, , 1870 †) - (SPHAERORTHOCERATIDAE) (FOSSIL)
- Semiannuloceras, Genus Semiannuloceras Evans , 2005 † (BALTOCERATIDAE) (FOSSIL)
- semiaperta, Epiphragmophora diluta semiaperta W.K. Weyrauch, 1967 - (EPIPHRAGMOPHORIDAE)
- semiaperta, Caracolus marginella semiaperta E.C. Von Martens - (PLEURODONTIDAE)
- semiarata, Sturia semiarata Mojsisovics, 1882 † - (STURIIDAE) (FOSSIL)
- semiarata, Meretrix semiarata A.E.M. Cossmann, 1906 † - (VENERIDAE) (FOSSIL)
- semiaratus, Melampus semiaratus M. Connolly, 1912 - (ELLOBIIDAE)
- semiarmatum, Epipeltoceras semiarmatum (F.A. von Quenstedt, 1887 †) - (ASPIDOCERATIDAE) (FOSSIL)
- semiaspera, Phlyctiderma semiaspera (R.A. Philippi, 1836) - (UNGULINIDAE)
- semiaspera, Diplodonta semiaspera R.A. Philippi, 1836 - syn of: Phlyctiderma semiaspera (R.A. Philippi, 1836) - (UNGULINIDAE)
- semiaspera, Diplodonta semiaspera R.A. Philippi, 1836 - syn of: Phlyctiderma semiaspera (R.A. Philippi, 1836) - (UNGULINIDAE)
- semiaspera, Felaniella semiaspera W.H. Dall † - syn of: Felaniella sertunayensis (Slodkewitsch, 1938 ex Kogan, MS †) - (UNGULINIDAE) (FOSSIL)
- semiaspera discrepans, Diplodonta semiaspera discrepans Carpenter, 1857 - syn of: Diplodonta zelandica Gray, 1835 - (UNGULINIDAE)
- semiasperoides, Cycladicama semiasperoides S. Nomura, 1932 - (UNGULINIDAE)
- semiaspersa discrepans, Diplodonta semiaspersa discrepans P.P. Carpenter, 1857 - syn of: Diplodonta orbella (Gould, 1851) - (UNGULINIDAE)
- semiasperum, Nemocardium semiasperum (G.P. Deshayes, 1858 †) - (CARDIIDAE) (FOSSIL)
- semiassa, Mangelia semiassa A.A. Gould, 1861 - (MANGELIIDAE)
- semiauratus, Melampus semiauratus M. Connolly, 1912 - (ELLOBIIDAE)
- semiaurea, Colsyrnola semiaurea A. Peñas & E. Rolán, 2016 - (PYRAMIDELLIDAE)
- Semiauricula, Genus Semiauricula A.E.M. Cossmann, 1889 (ELLOBIIDAE)
- semiaurita, Stachella semiaurita L. Waagen, 1880 † - (EUPHEMITIDAE) (FOSSIL)
- semiaurita, Margaritifera semiaurita O.A.L. Mörch, 1853 - syn of: Electroma alacorvi (L.W. Dillwyn, 1817) - (MARGARITIFERIDAE)
- semiaurita, Electroma semiaurita O.A.L. Mörch, 1853 - syn of: Electroma alacorvi (L.W. Dillwyn, 1817) - (PTERIIDAE)
- semiaurita, Isognomon semiaurita W.H. Dall & C.T. Simpson, 1901 - syn of: Isognomon bicolor (C.B. Adams, 1845) - (PTERIIDAE)
- Semibeyrichites, Genus Semibeyrichites Krystyn & Tatzreiter, 1991 † (BEYRICHITIDAE) (FOSSIL)
- semibistriata, Saccella semibistriata F.E. Eames, 1951 † - (NUCULANIDAE) (FOSSIL)
- Semibittium, Subgenus Bittium (Semibittium) A.E.M. Cossmann, 1896 † (CERITHIIDAE) (FOSSIL)
- Semibuliminus, Genus Semibuliminus O.F. von Möllendorff, 1899 (BRADYBAENIDAE)
- semicalcareus, Helicarion semicalcareus M.M. Schepman, 1896 - (HELICARIONIDAE)
- semicana, Annularops semicana (P.M.A. Morelet, 1851) - (POMATIIDAE)
- semicana nana, Annularops semicana nana (C. de la Torre & P. Bartsch, 1941) - (POMATIIDAE)
- semicana organicola, Annularops semicana organicola (C. de la Torre & P. Bartsch, 1941) - (POMATIIDAE)
- semicanaliculata, Pyramidella semicanaliculata C.J. Maury, 1917 - syn of: Longchaeus suturalis (H.C. Lea, 1843) - (PYRAMIDELLIDAE)
- semicanaliculatus, Belemnites semicanaliculatus H.M.D. de Blainville † - (BELEMNITELLIDAE) (FOSSIL)
- semicancellata, Yunnania semicancellata (de Koninck, 1881 †) - (ARAEONEMATIDAE) (FOSSIL)
- semicancellata, Varicospira semicancellata (Martin, 1899 †) - (ROSTELLARIIDAE) (FOSSIL)
- semicancellata, Venus semicancellata F.C.L. Koch in R.A. Philippi, 1843 - syn of: Macridiscus donacinus semicancellatus (F.C.L. Koch in R.A. Philippi, 1843) - (VENERIDAE)
- semicancellatus, Macridiscus donacinus semicancellatus (F.C.L. Koch in R.A. Philippi, 1843) - (VENERIDAE)
- Semicardiomya, syn of: Genus Myonera W.H. Dall, 1886 (CUSPIDARIIDAE)
- semicarinata, Partulina semicarinata W. Newcomb, 1854 - (ACHATINELLIDAE)
- semicarinata, Spinigera semicarinata (G.G. Münster, 1844 †) - (APORRHAIDAE) (FOSSIL)
- semicarinata, Archinacella semicarinata Ulrich & Scofield, 1897 † - (ARCHINACELLIDAE) (FOSSIL)
- semicarinata, Goniobasis semicarinata (T. Say, 1829) - (PLEUROCERIDAE)
- semicarinata, Rostellaria semicarinata Münster in G.A. Goldfuss, 1844 † - syn of: Spiniloma semicarinata (Münster in G.A. Goldfuss, 1844 †) - (ROSTELLARIIDAE) (FOSSIL)
- semicarinata, Spiniloma semicarinata (Münster in G.A. Goldfuss, 1844 †) - (SPINILOMATIDAE) (FOSSIL)
- semicarinata hayseldeni, Partulina semicarinata hayseldeni D.D. Baldwin, 1896 - (ACHATINELLIDAE)
- semicarinatum, Gyronema semicarinatum (Salter, 1859 †) - (LOPHOSPIRIDAE) (FOSSIL)
- semicarinatus, Guraleus semicarinatus (H.A. Pilsbry, 1904) - (MANGELIIDAE)
- semicarinatus, Onoba semicarinatus (L. de Folin, 1873) - (RISSOIDAE)
- semicarnea, Amastra mucronata semicarnea C.M.F. Ancey & E.R. Sykes, 1899 - (AMASTRIDAE)
- Semicassis, Genus Semicassis O.A.L. Mörch, 1852 (CASSIDAE)
- semicastanea, Hadra semicastanea (L. Pfeiffer, 1849) - (CAMAENIDAE)
- semicaudata, Mitrella semicaudata (L.M.D. Bellardi, 1849 †) - (COLUMBELLIDAE) (FOSSIL)
- semicaudata, Jouannetia semicaudata C. des Moulins, 1828 - (PHOLADIDAE)
- semicelatum, Orthodactylites semicelatum (C.T. Simpson, 1843 †) - (DACTYLIOCERATIDAE) (FOSSIL)
- semicincta, Acrotomina semicincta (O. Böttger, 1881) - (CLAUSILIIDAE)
- semicincta, Hamulina semicincta F.A. Roemer, 1841 † - syn of: Aegocrioceras semicinctum (F.A. Roemer, 1841 †) - (HAMULINIDAE) (FOSSIL)
- semicincta circassica, Acrotomina semicincta circassica (O.W. Von Rosen, 1901) - (CLAUSILIIDAE)
- semicincta ciscaucasica, Acrotoma semicincta ciscaucasica O.W. Von Rosen, 1901 - syn of: Acrotomina semicincta (O. Böttger, 1881) - (CLAUSILIIDAE)
- semicinctum, Aegocrioceras semicinctum (F.A. Roemer, 1841 †) - (AEGOCRIOCERATIDAE) (FOSSIL)
- semicinctum, Caecum semicinctum L. de Folin, 1867 - (CAECIDAE)
- semicinctum, Hamites semicinctum F.A. Roemer, 1841 † - syn of: Aegocrioceras semicinctum (F.A. Roemer, 1841 †) - (HAMITIDAE) (FOSSIL)
- semicinctus, Badepigrus semicinctus (W.L. May, 1915) - (ANABATHRIDAE)
- semicinctus, Bulimulus semicinctus H.A. Pilsbry, 1897 - (BULIMULIDAE)
- semicingulata, Clymenia semicingulata G.G. Münster, 1839 † - syn of: Clymenia laevigata (G.G. Münster, 1832 †) - (CLYMENIIDAE) (FOSSIL)
- semicingulatus, Acteon semicingulatus W.H. Dall, 1927 - (ACTEONIDAE)
- semicircula, Yamamotolepida semicircula T. Habe, 1976 - (GALEOMMATIDAE)
- Semicircularia, syn of: Genus Pelagiella Matthew, 1895 † (PELAGIELLIDAE) (FOSSIL)
- semicircularis, Mytilarca semicircularis Isberg, 1934 † - (AMBONYCHIIDAE) (FOSSIL)
- semicircularis, Plagiostoma semicircularis G.A. Goldfuss, 1835 † - (LIMIDAE) (FOSSIL)
- semicircularis, Actinopterinia semicircularis Isberg, 1934 † - (PTERIIDAE) (FOSSIL)
- semicirculatum, Trapezovitus semicirculatum Syssoiev, 1962 † - syn of: Trapezovitus sinscus A.V. Sysoev, 1958 † - (SULCAVITIDAE) (FOSSIL)
- semiclara, Clathropsis semiclara A. Cecalupo & I. Perugia, 2012 - (CERITHIOPSIDAE)
- semiclathrata, Sveltella semiclathrata (L.J. Morlet, 1885 †) - (CANCELLARIIDAE) (FOSSIL)
- semiclathratula, Liotina semiclathratula (L. von Schrenck, 1862) - (LIOTIIDAE)
- semiclatriata, Zafra semiclatriata W.J. Sleurs, 1987 - (COLUMBELLIDAE)
- semiclausa, Epiphragmophora semiclausa (E.C. Von Martens, 1868) - (EPIPHRAGMOPHORIDAE)
- semiclausa, Scintilla semiclausa G.B. II Sowerby, 1865 - (GALEOMMATIDAE)
- semiclausa, Neverita semiclausa G.P. Deshayes, 1864 † - (NATICIDAE) (FOSSIL)
- Semiclausaria, syn of: Genus Drymaeus J.A. Albers, 1850 (BULIMULIDAE)
- semiclausum, Gomphoceras semiclausum Barrande, 1865 † - syn of: Gonatocyrtoceras heteroclytum (Barrande, 1866 †) - (DIESTOCERATIDAE) (FOSSIL)
- semiclausum, Cayugoceras semiclausum Barrande, 1865 † - syn of: Gonatocyrtoceras heteroclytum (Barrande, 1866 †) - (MANDALOCERATIDAE) (FOSSIL)
- semiclausus, Murex semiclausus H.C. Küster, 1869 - syn of: Ocinebrina edwardsi (B.C.M. Payraudeau, 1826) - (MURICIDAE)
- semicolon, Crassispira semicolon (Sowerby, 1816 †) - (PSEUDOMELATOMIDAE) (FOSSIL)
- semicolon, Rimosodaphnella semicolon (S.V. Wood, 1842) - (RAPHITOMIDAE)
- semicolon, Pleurotoma semicolon Sowerby, 1816 † - syn of: Crassispira semicolon (Sowerby, 1816 †) - (TURRIDAE) (FOSSIL)
- semicolorata, Turbonilla semicolorata M. Yokoyama, 1927 - (PYRAMIDELLIDAE)
- semicoloratus, Tomelasmus semicoloratus (G.C. Spence, 1936) - (UROCOPTIDAE)
- semiconcava, Tibersyrnola semiconcava (W.B. Marshall & R. Murdoch, 1919 †) - (PYRAMIDELLIDAE) (FOSSIL)
- semiconcavus, Zeacolpus semiconcavus (H.H. Suter, 1917 †) - (TURRITELLIDAE) (FOSSIL)
- Semiconchula, Genus Semiconchula E. Naranjo-Garcia, O.J. Polaco & T.A. Pearce, 2000 (XANTHONYCHIDAE)
- semiconica, Mitra semiconica G.B. II Sowerby, 1874 - syn of: Ziba bacillum (J.B.P.A. Lamarck, 1811) - (MITRIDAE)
- semiconica, Neritina semiconica (J.B.P.A. Lamarck, 1822) - (NERITIDAE)
- semiconvexa, Mitrella semiconvexa (J.B.P.A. Lamarck, 1822) - (COLUMBELLIDAE)
- semiconvexa, Hydrobia semiconvexa C.L.F. von Sandberger, 1875 † - (HYDROBIIDAE) (FOSSIL)
- semiconvexum, Buccinum semiconvexum J.B.P.A. Lamarck, 1822 - syn of: Mitrella semiconvexa (J.B.P.A. Lamarck, 1822) - (BUCCINIDAE)
- semicora, Turrithyra semicora C. de la Torre & P. Bartsch, 1941 - (POMATIIDAE)
- semicora oicium, Turrithyra semicora oicium C. de la Torre & P. Bartsch, 1941 - (POMATIIDAE)
- Semicorallidomus, Genus Semicorallidomus Isberg, 1934 † (MODIOMORPHIDAE) (FOSSIL)
- Semicorbula, Genus Semicorbula Cossmann, 1909 † (CORBULIDAE) (FOSSIL)
- semicorneus, Trimusculus semicorneus (H.B. Preston, 1908) - (TRIMUSCULIDAE)
- Semicornus, syn of: Genus Chloritis H.H. Beck, 1837 (CAMAENIDAE)
- semicornutum, Dipoloceroides semicornutum (Spath, 1931 †) - (BRANCOCERATIDAE) (FOSSIL)
- semicoronata, Wrightudora semicoronata (J. Gundlach in L. Pfeiffer, 1861) - (POMATIIDAE)
- semicoronatum, Tympanotonos semicoronatum (J.B.P.A. Lamarck, 1804 †) - (POTAMIDIDAE) (FOSSIL)
- semicoronatus, Stephanoconus semicoronatus Frenguelli, 1946 † - (CONIDAE) (FOSSIL)
- semicoronatus, Conus semicoronatus Vinassa de Regny, 1897 † - (CONIDAE) (FOSSIL)
- semicorrugata, Aspatharia semicorrugata (H.B. Preston, 1909) - (IRIDINIDAE)
- semicosta, Hildoceras semicosta Buckman, 1926 † - syn of: Hildoceras semipolitum (Buckman, 1902 †) - (HILDOCERATIDAE) (FOSSIL)
- semicostata, Achatinella semicostata L. Pfeiffer, 1855 - syn of: Leptachatina semicostata (L. Pfeiffer, 1855) - (ACHATINELLIDAE)
- semicostata, Leptachatina semicostata (L. Pfeiffer, 1855) - (AMASTRIDAE)
- semicostata, Darellia semicostata S.S. Buckman, 1888 † - (AMMONOIDEA (UNASSIGNED)) (FOSSIL)
- semicostata, Dimeroclymenia semicostata Czarnocki, 1989 † - (BILOCLYMENIIDAE) (FOSSIL)
- semicostata, Cordieria semicostata (F.E. Edwards †) - (BORSONIIDAE) (FOSSIL)
- semicostata, Pisania semicostata R. Tate, 1888 † - (BUCCINIDAE) (FOSSIL)
- semicostata, Clionella semicostata (L.C. Kiener, 1840) - (CLAVATULIDAE)
- semicostata, Clymenia semicostata G.G. Münster, 1839 † - syn of: Costaclymenia semicostata (G.G. Münster, 1839 †) - (CLYMENIIDAE) (FOSSIL)
- semicostata, Costaclymenia semicostata (G.G. Münster, 1839 †) - (COSTACLYMENIIDAE) (FOSSIL)
- semicostata, Crassinella semicostata Scott 1970 † - (CRASSATELLIDAE) (FOSSIL)
- semicostata, Cardiomya semicostata (B. Prashad, 1932) - (CUSPIDARIIDAE)
- semicostata, Scalaria semicostata Wood, 1874 † - (EPITONIIDAE) (FOSSIL)
- semicostata, Mitra semicostata H.E. Anton, 1838 - syn of: Pusia semicostatum (H.E. Anton, 1838) - (MITRIDAE)
- semicostata, Geukensia semicostata T.A. Conrad, 1837 - syn of: Geukensia demissa (Dilwyn, 1817) - (MYTILIDAE)
- semicostata, Pseudocominella semicostata T.R. Nuttall & J. Cooper, 1973 † - (NASSARIIDAE) (FOSSIL)
- semicostata, Nassa semicostata É.A.A. Locard, 1887 † - syn of: Tritia cuvierii (B.C.M. Payraudeau, 1826 †) - (NASSARIIDAE) (FOSSIL)
- semicostata, Jouannetia semicostata W.H. Dall, 1898 - syn of: Jouannetia quillingi H. Turner, 1955 - (PHOLADIDAE)
- semicostata, Pinna semicostata R.A. Philippi, 1887 † - (PINNIDAE) (FOSSIL)
- semicostata, Pinna semicostata T.A. Conrad, 1837 - syn of: Pinna muricata C. Linnaeus, 1758 - (PINNIDAE)
- semicostata, Pseudozygopleura semicostata (F.B. Meek, 1871 †) - (PSEUDOZYGOPLEURIDAE) (FOSSIL)
- semicostata, Odostomia semicostata J. Brown, 1905 † - (PYRAMIDELLIDAE) (FOSSIL)
- semicostata, Tiberia semicostata E. Saurin, 1962 - (PYRAMIDELLIDAE)
- semicostata, Onoba semicostata (G. Montagu, 1803) - (RISSOIDAE)
- semicostata, Pusillina lineolata semicostata K.O. Milaschewitsch, 1909 - (RISSOIDAE)
- semicostata, Sinezona semicostata L.P. Burnay & E. Rolán, 1990 - (SCISSURELLIDAE)
- semicostata, Melania semicostata R.A. Philippi, 1847 - syn of: Sermyla riqueti (J.P.S. Grateloup, 1840) - (THIARIDAE)
- semicostata, Truncatella semicostata R.P. Montrouzier, 1862 - (TRUNCATELLIDAE)
- semicostata, Pleurotoma semicostata L.C. Kiener, 1840 - syn of: Clionella semicostata (L.C. Kiener, 1840) - (TURRIDAE)
- semicostata, Gongylostomella semicostata C. de la Torre & P. Bartsch, 1972 - (UROCOPTIDAE)
- semicostata, Gongylostomella strigis semicostata C. de la Torre & P. Bartsch, 1972 - (UROCOPTIDAE)
- semicostata striata, Onoba semicostata striata (J. Adams, 1797) - (RISSOIDAE)
- semicostatum, Arnioceras semicostatum (A.T. Young & Bird, 1828 †) - (ARIETITIDAE) (FOSSIL)
- semicostatum, Pusia semicostatum (H.E. Anton, 1838) - (COSTELLARIIDAE)
- semicostatum, Glottoceras semicostatum Sommermeier, 1910 † - (KNEMICERATIDAE) (FOSSIL)
- semicostatum, Potamides semicostatum (R. Tate, 1885 †) - (POTAMIDIDAE) (FOSSIL)
- semicostatum, Astralium semicostatum (L.C. Kiener, 1850) - (TURBINIDAE)
- semicostatum, Astralium semicostatum P. Fischer, 1875 - syn of: Astralium semicostatum (L.C. Kiener, 1850) - (TURBINIDAE)
- semicostatus, Arietites semicostatus (A.T. Young & Bird, 1828 †) - (ARIETITIDAE) (FOSSIL)
- semicostatus, Aviculopecten semicostatus (Portlock) † - (AVICULOPECTINIDAE) (FOSSIL)
- semicostatus, Pseudoaluco semicostatus (G.P. Deshayes, 1833 †) - (CERITHIIDAE) (FOSSIL)
- semicostatus, Winterbergiella semicostatus (G.A. Goldfuss, 1844 †) - (GOSSELETINIDAE) (FOSSIL)
- semicostatus, Cymatophos semicostatus (W.M. Gabb, 1873 †) - (NASSARIIDAE) (FOSSIL)
- semicostatus, Hoplitoplacenticeras plasticus semicostatus Paulcke, 1907 † - (PLACENTICERATIDAE) (FOSSIL)
- semicostatus, Trochus semicostatus L.C. Kiener, 1850 - syn of: Astralium semicostatum (L.C. Kiener, 1850) - (TROCHIDAE)
- semicostatus, Turbo semicostatus W.H. Pease, 1861 - syn of: Marmarostoma argyrostomus (C. Linnaeus, 1758) - (TURBINIDAE)
- semicostulata, Maackia herderiana semicostulata (W.A. Lindholm, 1924) - (AMNICOLIDAE)
- semicostulata, Omphalotropis semicostulata J.F. Quadras & O.F. von Möllendorff, 1894 - (ASSIMINEIDAE)
- semicostulata, Albinaria menelaus semicostulata (O. Böttger, 1878) - (CLAUSILIIDAE)
- semicostulata, Mangelia semicostulata G.P. Deshayes, 1865 † - (MANGELIIDAE) (FOSSIL)
- semicostulata, Rissoa semicostulata H.E. Anton, 1838 - syn of: Rissoa parva (E.M. Da Costa, 1778) - (RISSOIDAE)
- semicostulata, Spiniloma semicostulata (L.É.S. Piette & Deslongchamps, 1864 †) - (SPINILOMATIDAE) (FOSSIL)
- semicostulata, Stosicia semicostulata (Boettger, 1887 †) - (ZEBINIDAE) (FOSSIL)
- semicostulatum, Lissoceras semicostulatum Buckman † - (HAPLOCERATIDAE) (FOSSIL)
- semicostulatus, Hemicymbites semicostulatus (Reynès, 1879 †) - (ARIETITIDAE) (FOSSIL)
- semicostulatus, Arietites semicostulatus Reynès, 1879 † - syn of: Hemicymbites semicostulatus (Reynès, 1879 †) - (ARIETITIDAE) (FOSSIL)
- semicrenulata, Nuculana semicrenulata C.T. Trechmann, 1918 † - (NUCULANIDAE) (FOSSIL)
- semiculta, Lycettitrigonia semiculta (E. Forbes, 1846 †) - (RUTITRIGONIIDAE) (FOSSIL)
- semiculta, Trigonia semiculta E. Forbes, 1845 † - syn of: Lycettitrigonia semiculta (E. Forbes, 1846 †) - (TRIGONIIDAE) (FOSSIL)
- Semicyclus, syn of: Genus Hemicricus M. Churkin & C. Carter, 1971 † (TENTACULITIDA (UNASSIGNED)) (FOSSIL)
- semicylindrica, Ostrea semicylindrica T. Say, 1822 - syn of: Crassostrea virginica (J.F. Gmelin, 1791) - (OSTREIDAE)
- Semicypraea, Genus Semicypraea F.A. Schilder, 1936 † (CYPRAEIDAE) (FOSSIL)
- semidecora, Phidiana semidecora (W.H. Pease, 1860) - (FACELINIDAE)
- semidecussata, Archachatina semidecussata (L. Pfeiffer, 1861) - (ACHATINIDAE)
- semidecussata, Euplecta semidecussata (L. Pfeiffer, 1853) - (ARIOPHANTIDAE)
- semidecussata, Tropidophora semidecussata L. Pfeiffer, 1847 - (POMATIIDAE)
- semidecussata, Rissoina semidecussata Boettger, 1901 † - (RISSOINIDAE) (FOSSIL)
- semidecussata, Bayania semidecussata (J.B.P.A. Lamarck, 1804 †) - (THIARIDAE) (FOSSIL)
- semidecussata, Tapes semidecussata L.A. Reeve, 1864 - syn of: Venerupis philippinarum (A. Adams & L.A. Reeve, 1850) - (VENERIDAE)
- semidecussata aplustre, Tropidophora semidecussata aplustre (G.B. Sowerby, 1849) - (POMATIIDAE)
- semidecussata macaraea, Tropidophora semidecussata macaraea S.A.A. Petit De La Saussaye, 1853 - (POMATIIDAE)
- semidecussata paulucciae, Tropidophora semidecussata paulucciae J.C.H. Crosse & P.H. Fischer, 1882 - syn of: Tropidophora paulucciae (J.C.H. Crosse & P.H. Fischer, 1882) - (POMATIIDAE)
- semidecussata pauluccioides, Tropidophora semidecussata pauluccioides E. Fischer-Piette, Ch.P. Blanc, F. Blanc & F. Salvat, 1993 - (POMATIIDAE)
- semidecussata volvuloides, Tropidophora semidecussata volvuloides G.B. Sowerby, 1850 - (POMATIIDAE)
- semidecussatum, Nemocardium semidecussatum A. von Koenen † - (CARDIIDAE) (FOSSIL)
- semidens, Granopupa semidens C.A. Westerlund, 1892 - syn of: Granopupa granum (J.P.R. Draparnaud, 1801) - (CHONDRINIDAE)
- Semidentamarginella, syn of: Genus Marginella J.B.P.A. Lamarck, 1799 (MARGINELLIDAE)
- semidentata, Anadara semidentata G.P. Deshayes, 1850 - syn of: Lunarca ovalis (J.G. Bruguière, 1789) - (ARCIDAE)
- semidentata, Arca semidentata G.P. Deshayes, 1850 - syn of: Lunarca ovalis (J.G. Bruguière, 1789) - (ARCIDAE)
- semidentata, Tellina semidentata A. Scacchi, 1833 - syn of: Abra alba (Wood, 1802) - (TELLINIDAE)
- semidentatus, Theodoxus semidentatus (C.L.F. von Sandberger, 1875 †) - (NERITIDAE) (FOSSIL)
- semidenticulata, Schilderia semidenticulata (F. Sacco, 1894 †) - (CYPRAEIDAE) (FOSSIL)
- semidisjuncta, Cycloscala semidisjuncta (J.G. Jeffreys, 1884) - (EPITONIIDAE)
- semidisjuncta, Ocenebra semidisjuncta W.H. Turton, 1932 - syn of: Vaughtia babingtoni (G.B. III Sowerby, 1892) - (MURICIDAE)
- semidisjunctum, Trigonostoma semidisjunctum (G.B. II Sowerby, 1849) - (CANCELLARIIDAE)
- semidivisa, Marathonites semidivisa Ruzhentsev, 1933 † - syn of: Kargalites typicus (Ruzhentsev, 1933 †) - (ADRIANITIDAE) (FOSSIL)
- semielliptica, Perna semielliptica Seeley † - (MYTILIDAE) (FOSSIL)
- Semierycina, Genus Semierycina T.A. de M. Monterosato, 1911 (LASAEIDAE)
- semieudoxus, Pararasenia semieudoxus Schneid, 1939 † - (AULACOSTEPHANIDAE) (FOSSIL)
- semifacta, Fetaspira semifacta Mazaev, 2015 † - (PHYMATOPLEURIDAE) (FOSSIL)
- semifasciata, Mitra semifasciata J.B.P.A. Lamarck, 1811 - syn of: Vexillum semifasciatum (J.B.P.A. Lamarck, 1811) - (MITRIDAE)
- semifasciatum, Vexillum semifasciatum (J.B.P.A. Lamarck, 1811) - (COSTELLARIIDAE)
- semifasciatum, Costellaria semifasciatum J.B.P.A. Lamarck, 1811 - syn of: Vexillum semifasciatum (J.B.P.A. Lamarck, 1811) - (COSTELLARIIDAE)
- semifasciatus, Drymaeus semifasciatus A. Mousson, 1869 - (BULIMULIDAE)
- semiferruginea, Cerithium litteratum semiferruginea J.B.P.A. Lamarck, 1822 - (CERITHIIDAE)
- semiferruginea, Mitra semiferruginea L.A. Reeve, 1845 - (MITRIDAE)
- semiferrugineum, Cerithium semiferrugineum J.B.P.A. Lamarck, 1822 - syn of: Cerithium litteratum (I. von Born, 1778) - (CERITHIIDAE)
- semifimbriatum, Penicillus semifimbriatum J.C. Chenu, 1842 - syn of: Verpa penis (C. Linnaeus, 1758) - (PENICILLIDAE)
- semiflammea, Bullia semiflammea L.A. Reeve, 1846 - syn of: Bullia digitalis (L.W. Dillwyn, 1817) - (NASSARIIDAE)
- semiflexum, Sporadoceras semiflexum Schindewolf, 1923 † - (SPORADOCERATIDAE) (FOSSIL)
- Semiformiceras, Genus Semiformiceras Spath, 1925 † (OPPELIIDAE) (FOSSIL)
- semifossilis, Tellina semifossilis G.B. Sowerby, 1867 - syn of: Tellina deltoidalis J.B.P.A. Lamarck, 1818 - (TELLINIDAE)
- semifrenatus, Amphidromus semifrenatus E.C. Von Martens, 1900 - (CAMAENIDAE)
- Semifruticicola, Genus Semifruticicola A. Wagner, 1914 (HYGROMIIDAE)
- semifulva, Helix semifulva J.W. Taylor, 1912 - syn of: Theba dehnei (E.A. Rossmässler, 1846) - (HELICIDAE)
- semifulva, Periglypta semifulva K.T. Menke, 1847 - syn of: Tivela byronensis (J.E. Gray, 1838) - (VENERIDAE)
- semifusca, Achatina schweinfurthi semifusca G.C. Spence, 1923 - (ACHATINIDAE)
- semifusca, Modiola semifusca G.B. I Sowerby, 1825 - syn of: Mytella guyanensis (J.B.P.A. Lamarck, 1819) - (MYTILIDAE)
- semifuscus, Modiolus semifuscus J.B.P.A. Lamarck - syn of: Modiolus auriculatus C.F.F. von Krauss, 1848 - (MYTILIDAE)
- Semifusus, syn of: Genus Hemifusus W.J. Swainson, 1840 (MELONGENIDAE)
- Semifusus, Genus Semifusus Swainson, 1840 † (TURBINELLIDAE) (FOSSIL)
- semiglaber, Trypanostylus semiglaber Münster, 1841 † - (COELOSTYLINIDAE) (FOSSIL)
- semiglaber, Aquilofusus semiglaber (A.H.E. Beyrich, 1856 †) - (FASCIOLARIIDAE) (FOSSIL)
- semiglabra, Turbonilla semiglabra S. Clessin, 1902 - (PYRAMIDELLIDAE)
- semiglabra, Turritella semiglabra Münster, 1841 † - syn of: Trypanostylus semiglaber Münster, 1841 † - (TURRITELLIDAE) (FOSSIL)
- semiglabrata, Brotia oppenoorthi semiglabrata C.H. Oostingh, 1935 - (PACHYCHILIDAE)
- semiglabrata, Rissoina semiglabrata A. Adams, 1854 - syn of: Zebina semiglabrata Adams, 1854 - (RISSOINIDAE)
- semiglabrata, Zebina semiglabrata Adams, 1854 - (ZEBINIDAE)
- semiglabrum, Cardium semiglabrum Phillips, 1829 † - (CARDIIDAE) (FOSSIL)
- semiglabrus, Otohoplites guersanti semiglabrus T.L. Casey † - (HOPLITIDAE) (FOSSIL)
- semiglobosa, Solenosteira semiglobosa R.J.L. Guppy, 1911 † - syn of: Solenosteira cochlearis (R.J.L. Guppy, 1873 †) - (BUCCINIDAE) (FOSSIL)
- semiglobosa, Hemiglypta semiglobosa (L. Pfeiffer) - (HELICARIONIDAE)
- semiglobosa, Myalina semiglobosa Isberg, 1934 † - (MYALINIDAE) (FOSSIL)
- semiglobosa, Neverita semiglobosa J.P.S. Grateloup, 1847 † - (NATICIDAE) (FOSSIL)
- semiglobosa, Polypylis semiglobosa I.M. Moskvicheva in Dworiadkin, 1980 - (PLANORBIDAE)
- semiglobosus, Trochus semiglobosus A. Aradas, 1847 - syn of: Gibbula pennanti (R.A. Philippi, 1846) - (TROCHIDAE)
- semiglobosus, Homerites semiglobosus J. Von Hauer, 1855 † - (TROPITIDAE) (FOSSIL)
- semiglobulus, Microcystina semiglobulus (O.F. von Möllendorff) - (ARIOPHANTIDAE)
- Semignomon, Subgenus Isognomon (Semignomon) Repin, 2013 † (MALLEIDAE) (FOSSIL)
- semigradata, Gradiella semigradata (E.A.L. Kittl, 1894 †) - (COELOSTYLINIDAE) (FOSSIL)
- semigradata, Elimia semigradata (I. Lea, 1862) - (PLEUROCERIDAE)
- semigradata, Valvata semigradata P.S. Pavlovic, 1927 † - (VALVATIDAE) (FOSSIL)
- semigranata, Gregariella semigranata (L.A. Reeve, 1858) - (MYTILIDAE)
- semigranosa, Archachatina semigranosa L. Pfeiffer, 1861 - (ACHATINIDAE)
- semigranosa, Bursa granularis semigranosa (G.P. Deshayes, 1846) - (BURSIDAE)
- semigranosa, Semicassis semigranosa (J.B.P.A. Lamarck, 1822) - (CASSIDAE)
- semigranosa, Cassis semigranosa J.B.P.A. Lamarck, 1822 - syn of: Semicassis semigranosa (J.B.P.A. Lamarck, 1822) - (CASSIDAE)
- semigranosa, Hemiglypta semigranosa (G.B. I Sowerby, 1832) - (HELICARIONIDAE)
- semigranosa, Mitra semigranosa E.C. Von Martens, 1897 - (MITRIDAE)
- semigranosa, Musculus semigranosa R. Tate, 1886 † - (MYTILIDAE) (FOSSIL)
- semigranosa, Nassa semigranosa R.W. Dunker, 1846 - syn of: Nassarius nigellus (L.A. Reeve, 1854) - (NASSARIIDAE)
- semigranosa, Crassispira semigranosa (L.A. Reeve, 1846) - (PSEUDOMELATOMIDAE)
- semigranosa, Ranella semigranosa J.B.P.A. Lamarck, 1822 - syn of: Bursa corrugata (Perry, 1811) - (RANELLIDAE)
- semigranosa, Tarebia semigranosa (G. von dem Busch) - (THIARIDAE)
- semigranosa, Pisanella semigranosa (P. Nyst, 1845 †) - (TURBINELLIDAE) (FOSSIL)
- semigranosa, Psoronaias semigranosa (G. von dem Busch in R.A. Philippi, 1845) - (UNIONIDAE)
- semigranosum, Buccinum semigranosum R.W. Dunker, 1846 - syn of: Nassarius nigellus (L.A. Reeve, 1854) - (BUCCINIDAE)
- semigranosum, Phalium semigranosum J.B.P.A. Lamarck, 1822 - syn of: Semicassis semigranosa (J.B.P.A. Lamarck, 1822) - (CASSIDAE)
- semigranosum, Rhinoclavis semigranosum J.B.P.A. Lamarck, 1822 - syn of: Rhinoclavis bituberculata (G.B. II Sowerby, 1855) - (CERITHIIDAE)
- semigranosus, Rhinoclavis semigranosus W. Wood, 1825 - syn of: Rhinoclavis bituberculata (G.B. II Sowerby, 1855) - (CERITHIIDAE)
- semigranosus, Donax semigranosus R.W. Dunker, 1877 - (DONACIDAE)
- semigranosus, Diplodon semigranosus C.T. Simpson, 1914 - syn of: Diplodon expansus semigranosus C.T. Simpson, 1914 - (HYRIIDAE)
- semigranosus, Diplodon expansus semigranosus C.T. Simpson, 1914 - (HYRIIDAE)
- semigranosus tropicus, Donax semigranosus tropicus O.A. Scarlato, 1965 - (DONACIDAE)
- semigranulosa, Melanopsis semigranulosa G.P. Deshayes, 1832 - (MELANOPSIDAE)
- semigranulosum, Bittium semigranulosum (J.B.P.A. Lamarck, 1804 †) - (CERITHIIDAE) (FOSSIL)
- semihastatus, Hibolithes semihastatus H.M.D. de Blainville, 1827 † - (MESOHIBOLITHIDAE) (FOSSIL)
- semiinflata, Venericardia semiinflata A.E.M. Cossmann & G. Pissarro, 1927 † - (CARDITIDAE) (FOSSIL)
- semiinflata, Crassispira semiinflata J. Grant & H.R. Gale, 1931 - (PSEUDOMELATOMIDAE)
- semiinflata redondoensis, Crassispira semiinflata redondoensis T.A. Burch, 1938 - syn of: Burchia redondoensis (T.A. Burch, 1938) - (PSEUDOMELATOMIDAE)
- semiinversum, Puncticeras semiinversum (Sobolew, 1914 †) - (CHEILOCERATIDAE) (FOSSIL)
- semilabiata, Delima montenegrina semilabiata (R. Walderdorff, 1864) - (CLAUSILIIDAE)
- semilabris, Chondropoma semilabris (J.B.P.A. Lamarck) - (POMATIIDAE)
- semilaeve, Caecum semilaeve P.P. Carpenter, 1857 - (CAECIDAE)
- semilaeve, Hatchericeras semilaeve H.A. Leanza, 1970 † - syn of: Hatchericeras patagonense Stanton, 1901 † - (NEOCOMITIDAE) (FOSSIL)
- semilaevigata, Rugobela semilaevigata C.R. Laws, 1935 † - (MURICIDAE) (FOSSIL)
- semilaevigata, Brotia costula semilaevigata T.N. Annandale, 1921 - (PACHYCHILIDAE)
- semilaevigata, Turbonilla semilaevigata (C.R. Laws, 1937 †) - (PYRAMIDELLIDAE) (FOSSIL)
- semilaevigatus, Modiolus semilaevigatus G.P. Deshayes, 1858 † - (MYTILIDAE) (FOSSIL)
- semilaevigatus, Tectus semilaevigatus Gregorio in Dainelli, 1905 † - (TEGULIDAE) (FOSSIL)
- semilaevis, Acteon semilaevis A.E. Ortmann, 1900 † - (ACTEONIDAE) (FOSSIL)
- semilaevis, Ancilla semilaevis (J.E. Tenison-Woods, 1877 †) - (ANCILLARIIDAE) (FOSSIL)
- semilaevis, Leucophysema semilaevis (G. Seguenza, 1879) - (BULLIDAE)
- semilaevis, Zaclys semilaevis (J.E. Tenison-Woods, 1877) - (CERITHIOPSIDAE)
- semilaevis, Carinigera semilaevis O. Böttger, 1889 - syn of: Inchoatia haussknechti semilaevis (O. Böttger, 1889) - (CLAUSILIIDAE)
- semilaevis, Inchoatia haussknechti semilaevis (O. Böttger, 1889) - (CLAUSILIIDAE)
- semilaevis, Clavatula semilaevis R.A. Philippi, 1846 † - (CLAVATULIDAE) (FOSSIL)
- semilaevis, Euryzone semilaevis (E.F.R.K. Koken, 1889 †) - (GOSSELETINIDAE) (FOSSIL)
- semilaevis, Plagiostoma semilaevis Cragin, 1893 † - (LIMIDAE) (FOSSIL)
- semilaevis, Brachidontes semilaevis (K.T. Menke, 1848) - (MYTILIDAE)
- semilaevis, Modiolus semilaevis K.T. Menke, 1848 - syn of: Brachidontes semilaevis (K.T. Menke, 1848) - (MYTILIDAE)
- semilaevis, Serripecten semilaevis (McCoy, 1876 †) - (PECTINIDAE) (FOSSIL)
- semilaevis, Tropidoceras semilaevis Fucini, 1899 † - (POLYMORPHITIDAE) (FOSSIL)
- semilaevis, Neocraspedites semilaevis (A. von Koenen, 1902 †) - (POLYPTYCHITIDAE) (FOSSIL)
- semilaevis, Ranella semilaevis J. Noszky, 1940 - syn of: Ranella olearium (C. Linnaeus, 1758) - (RANELLIDAE)
- semilaevis, Rissoa semilaevis A. von Koenen, 1892 † - (RISSOIDAE) (FOSSIL)
- semilaevis, Roxania semilaevis (G. Seguenza, 1880) - (SCAPHANDRIDAE)
- semilaevis, Dosinia semilaevis R.A. Philippi, 1887 † - (VENERIDAE) (FOSSIL)
- semilaevis alticola, Carinigera semilaevis alticola H. Nordsieck, 1974 - syn of: Inchoatia haussknechti alticola (H. Nordsieck, 1974) - (CLAUSILIIDAE)
- semilaevis tavropodensis, Carinigera semilaevis tavropodensis W.A. Fauer, 1993 - syn of: Carinigera megdova tavropodensis (W.A. Fauer, 1993) - (CLAUSILIIDAE)
- semilamellata, Pravispira semilamellata (A. Mousson, 1863) - (CLAUSILIIDAE)
- semilamellata, Petricola semilamellata J.B.P.A. Lamarck, 1818 - syn of: Petricola lithophaga (A. Retzius, 1788) - (VENERIDAE)
- semilamellata serrulosa, Clausilia semilamellata serrulosa O. von Retowski, 1889 - syn of: Pravispira semilamellata (A. Mousson, 1863) - (CLAUSILIIDAE)
- semilamellosa, Periglypta semilamellosa F.M. Delessert, 1841 - syn of: Hysteroconcha lupanaria (R.P. Lesson, 1831) - (VENERIDAE)
- Semilaoma, Genus Semilaoma T. Iredale, 1944 (PUNCTIDAE)
- semilenis, Braunsella semilenis S.S. Buckman, 1904† - (HILDOCERATIDAE) (FOSSIL)
- semileve, Hysteroceras semileve F. Haas, 1942 † - (BRANCOCERATIDAE) (FOSSIL)
- semilevigata, Falsicolus semilevigata C.R. Laws, 1932 † - (FASCIOLARIIDAE) (FOSSIL)
- semilevis, Palaina macgillivrayi semilevis T. Iredale, 1944 - (DIPLOMMATINIDAE)
- semilevis, Nerita semilevis L.W. Stephenson, 1953 † - (NERITIDAE) (FOSSIL)
- semilicentrifugata, Timoclea semilicentrifugata J.M.R.M. Viader, 1951 - syn of: Tawera similicentrifuga (J.M.R.M. Viader, 1951) - (VENERIDAE)
- Semilimacella, Subgenus Vitrina (Semilimacella) L. Soós, 1917 (VITRINIDAE)
- semilimata, Ringicula semilimata W.H. Dall † - (RINGICULIDAE) (FOSSIL)
- semilimax, Helix semilimax A.E.J. Férussac, 1802 - syn of: Semilimax semilimax (A.E.J. Férussac, 1802) - (HELICIDAE)
- Semilimax, Genus Semilimax A.E.R. Agassiz, 1845 (VITRINIDAE)
- semilimax, Semilimax semilimax (A.E.J. Férussac, 1802) - (VITRINIDAE)
- semilineata, Lienardia semilineata (A. Garrett, 1873) - (CLATHURELLIDAE)
- semilineata, Enoploteuthis semilineata D.O. Alexeyev, 1994 - (ENOPLOTEUTHIDAE)
- semilineata, Tropidophora semilineata P.M.A. Morelet, 1881 - syn of: Tropidophora semilirata P.M.A. Morelet, 1881 - (POMATIIDAE)
- semilineata, Kermia semilineata A. Garrett, 1873 - syn of: Kermia granosa (R.W. Dunker, 1871) - (RAPHITOMIDAE)
- semilirata, Assiminea semilirata O. Böttger, 1893 - (ASSIMINEIDAE)
- semilirata, Tropidophora semilirata P.M.A. Morelet, 1881 - (POMATIIDAE)
- semilirata, Cryptodaphne semilirata (Powell, 1942 †) - (RAPHITOMIDAE) (FOSSIL)
- semiliratus, Dombarites semiliratus Ruzhentsev & Bogoslovskaya, 1971 † - (DELEPINOCERATIDAE) (FOSSIL)
- semiliratus, Dendrochiton semiliratus (S.S. Berry, 1927) - (LEPIDOCHITONIDAE)
- semilobatum, Cymatoceras semilobatum L. Spengler, 1910 † - (CYMATOCERATIDAE) (FOSSIL)
- semilugubris, Vaceuchelus semilugubris (G.P. Deshayes, 1863) - (CHILODONTIDAE)
- semilugubris, Nerita semilugubris G.P. Deshayes, 1864 † - (NERITIDAE) (FOSSIL)
- semilugubris, Turbo semilugubris G.P. Deshayes, 1863 - syn of: Vaceuchelus semilugubris (G.P. Deshayes, 1863) - (TURBINIDAE)
- Semilukispira, Genus Semilukispira Blodgett & Frýda, 1999 † (BELLEROPHONTIDAE) (FOSSIL)
- semilunaris, Cancellaria semilunaris J.F. Gmelin, 1791 - syn of: Solatia piscatoria (J.F. Gmelin, 1791) - (CANCELLARIIDAE)
- semilunaris, Murex semilunaris J.F. Gmelin, 1791 - syn of: Solatia piscatoria (J.F. Gmelin, 1791) - (MURICIDAE)
- semilunaris, Tricula semilunaris N.T. Dang & T.H. Ho, 2006 - (POMATIOPSIDAE)
- semilunata, Etheria semilunata J.B.P.A. Lamarck, 1807 - syn of: Etheria elliptica J.B.P.A. Lamarck, 1807 - (ETHERIIDAE)
- semilunata, Diodora semilunata T. Habe, 1953 - (FISSURELLIDAE)
- semilunata, Naticarius semilunata Lea, 1833 † - (NATICIDAE) (FOSSIL)
- semilunatum, Hammatoceras semilunatum F.A. von Quenstedt, 1885 † - (HAMMATOCERATIDAE) (FOSSIL)
- semilunulata, Palaeomutela semilunulata Amalitsky, 1892, † - (PALAEOMUTELIDAE) (FOSSIL)
- semilunus, Dermatobranchus semilunus T.M. Gosliner & S.J. Fahey, 2011 - (ARMINIDAE)
- semilyrata, Rectoclymenia semilyrata Nikolaeva & Ivanovich, 2005 † - (RECTOCLYMENIIDAE) (FOSSIL)
- semimaculatus, Mesembrinus semimaculatus H.A. Pilsbry, 1898 - (BULIMULIDAE)
- semimaculatus perversus, Mesembrinus semimaculatus perversus H.A. Pilsbry, 1926 - (BULIMULIDAE)
- semimalleatus, Megalobulimus lichtensteini semimalleatus (H.C. Fulton, 1905) - (MEGALOBULIMIDAE)
- semimammatum, Epipeltoceras semimammatum F.A. von Quenstedt, 1885 † - (ASPIDOCERATIDAE) (FOSSIL)
- semimarginata, Clavatula semimarginata (J.B.P.A. Lamarck, 1822 †) - (CLAVATULIDAE) (FOSSIL)
- semimarginata, Pleurotoma semimarginata J.B.P.A. Lamarck, 1822 † - syn of: Clavatula semimarginata (J.B.P.A. Lamarck, 1822 †) - (TURRIDAE) (FOSSIL)
- semimarginata, Conomitra semimarginata (A.H.E. Beyrich, 1854 †) - (VOLUTOMITRIDAE) (FOSSIL)
- semimbricatum, Hemicosmorthoceras semimbricatum Gnoli, 1982 † - (SPHAERORTHOCERATIDAE) (FOSSIL)
- semimembranaceus, Zonitarion semimembranaceus (E.C. Von Martens, 1876) - (UROCYCLIDAE)
- Semimodiola, Genus Semimodiola A.E.M. Cossmann, 1887 † (MYTILIDAE) (FOSSIL)
- Semimopalia, syn of: Genus Plaxiphora J.E. Gray, 1847 (MOPALIIDAE)
- Semimytilus, Genus Semimytilus T. Soot-Ryen, 1955 (MYTILIDAE)
- seminalis, Fluminicola seminalis (R.B. Hinds, 1842) - (LITHOGLYPHIDAE)
- Seminella, Genus Seminella W.H. Pease, 1868 (COLUMBELLIDAE)
- seminella, Caryocorbula seminella (W.H. Dall, 1898 †) - (CORBULIDAE) (FOSSIL)
- Semineritina, Genus Semineritina A.E.M. Cossmann, 1925 † (NERITIDAE) (FOSSIL)
- seminflata, Venericardia seminflata A.E.M. Cossmann & G. Pissarro, 1927 † - (CARDITIDAE) (FOSSIL)
- seminiana, Moitessieria seminiana H.D. Boeters, 2003 - (MOITESSIERIIDAE)
- seminifera, Turricula seminifera A.A. Gould, 1849 - syn of: Inquisitor interrupta (J.B.P.A. Lamarck, 1816) - (CLAVATULIDAE)
- seminigra, Achatinella seminigra W.J. Swainson, 1828 - syn of: Achatinella apexfulva (G. Dixon, 1789) - (ACHATINELLIDAE)
- seminigra, Amastra seminigra A. Hyatt & H.A. Pilsbry, 1911 - (AMASTRIDAE)
- seminium, Afropunctum seminium (P.M.A. Morelet, 1873) - (EUCONULIDAE)
- seminium, Belgrandiella seminium (P.M.A. Morelet, 1857) - (HYDROBIIDAE)
- seminodosa, Cheeneetnukia seminodosa (Grüneberg, 1927 †) - (CHEENEETNUKIIDAE) (FOSSIL)
- seminodosa, Alectrion seminodosa C.B. Adams, 1852 - syn of: Nassarius hirtus (L.C. Kiener, 1834) - (NASSARIIDAE)
- seminodosa, Alvania seminodosa W.L. May, 1915 - syn of: Onoba australiae (G.R. von Frauenfeld, 1867) - (RISSOIDAE)
- seminodosa, Zygopleura seminodosa A. Nützel & Senowbari-Daryan, 1999 † - (ZYGOPLEURIDAE) (FOSSIL)
- seminodosus, Toxoceratoides seminodosus (F.A. Roemer, 1841 †) - (ANCYLOCERATIDAE) (FOSSIL)
- seminodosus, Hamites seminodosus F.A. Roemer, 1841 † - syn of: Toxoceratoides seminodosus (F.A. Roemer, 1841 †) - (HAMITIDAE) (FOSSIL)
- seminoides, Caryocorbula seminoides Gardner, 1928 † - (CORBULIDAE) (FOSSIL)
- seminola, Pterorytis seminola A.A. Olsson & R.E. Petit, 1964 † - (MURICIDAE) (FOSSIL)
- Seminola, Genus Seminola Wade, 1917 † (NEOGASTROPODA (UNASSIGNED)) (FOSSIL)
- seminole, Pyruella seminole E.J. Petuch, 1982 † - (BUSYCONIDAE) (FOSSIL)
- seminole, Fasciolaria seminole E.J. Petuch, 1994 † - (FASCIOLARIIDAE) (FOSSIL)
- seminole, Terebraspira seminole E.J. Petuch, 1994 † - (FASCIOLARIIDAE) (FOSSIL)
- seminole, Littorina seminole E.J. Petuch, 1991 † - (LITTORINIDAE) (FOSSIL)
- seminole, Seminolina seminole (H.A. Pilsbry, 1934 †) - (PLANORBIDAE) (FOSSIL)
- seminole, Turritella seminole E.J. Petuch, 1994 † - (TURRITELLIDAE) (FOSSIL)
- seminole, Scaphella seminole E.J. Petuch, 1994 † - (VOLUTIDAE) (FOSSIL)
- Seminoleconus, syn of: Genus Stephanoconus O.A.L. Mörch, 1852 (CONIDAE)
- Seminoleconus, syn of: Genus Conus C. Linnaeus, 1758 (CONIDAE)
- seminolense, Pseudorthoceras seminolense Girty, 1911 † - syn of: Pseudorthoceras knoxense (McChesney, 1859 †) - (PSEUDORTHOCERATIDAE) (FOSSIL)
- seminolensis, Cardita seminolensis A.A. Olsson, 1967 † - (CARDITIDAE) (FOSSIL)
- seminolensis, Muricopsis seminolensis E.H. Vokes & R. Houart, 1986 - (MURICIDAE)
- Seminolina, Subgenus Planorbella (Seminolina) H.A. Pilsbry, 1934 (PLANORBIDAE)
- seminolum, Calliostoma seminolum A.A. Olsson & A. Harbison, 1953 † - (CALLIOSTOMATIDAE) (FOSSIL)
- seminolum, Strioterebrum seminolum A.A. Olsson, 1967 † - (TEREBRIDAE) (FOSSIL)
- seminuda, Amastra seminuda D.D. Baldwin, 1906 - (AMASTRIDAE)
- seminuda, Insolentia seminuda (H.H. Suter, 1917 †) - (CONOIDEA (UNASSIGNED)) (FOSSIL)
- seminuda, Bembexia seminuda (Whidborne, 1892 †) - (EOTOMARIIDAE) (FOSSIL)
- seminuda, Vilasina seminuda (W.H. Dall, 1897) - (MYTILIDAE)
- seminuda, Modiolaria seminuda W.H. Dall, 1897 - syn of: Vilasina seminuda (W.H. Dall, 1897) - (MYTILIDAE)
- seminuda, Cycladamsia seminuda (C.B. Adams, 1851) - (NEOCYCLOTIDAE)
- seminuda, Eirlysia seminuda Mazaev, 2015 † - (PHYMATOPLEURIDAE) (FOSSIL)
- seminuda, Cyrtopinna seminuda (J.B.P.A. Lamarck, 1819) - (PINNIDAE)
- seminuda, Pleurotomaria seminuda Whidborne, 1892 † - syn of: Bembexia seminuda (Whidborne, 1892 †) - (PLEUROTOMARIIDAE) (FOSSIL)
- seminuda, Boonea seminuda (Adams, 1839) - (PYRAMIDELLIDAE)
- seminuda, Odostomia seminuda Auct. non C.B. Adams, 1839 - syn of: Chrysallida minutissima (P. Dautzenberg & H. Fischer, 1906) - (PYRAMIDELLIDAE)
- seminuda, Pusillina seminuda (L. Seguenza, 1903) - syn of: Pusillina munda seminuda (L. Seguenza, 1903) - (RISSOIDAE)
- seminuda, Pusillina munda seminuda (L. Seguenza, 1903) - (RISSOIDAE)
- seminuda, Macoma seminuda K.B. Barinov & al., 1992 † - (TELLINIDAE) (FOSSIL)
- seminuda, Thracia seminuda O.A. Scarlato, 1981 - syn of: Thracia septentrionalis J.G. Jeffreys, 1872 - (THRACIIDAE)
- seminuda, Brachypodella seminuda C.B. Adams, 1845 - (UROCOPTIDAE)
- seminuda, Yoldia seminuda W.H. Dall, 1871 - (YOLDIIDAE)
- seminuda ensifera, Yoldia seminuda ensifera W.H. Dall, 1897 - (YOLDIIDAE)
- seminuda humile, Cycladamsia seminuda humile P. Bartsch, 1942 - syn of: Cycladamsia seminuda (C.B. Adams, 1851) - (NEOCYCLOTIDAE)
- seminuda scabratum, Cycladamsia seminuda scabratum P. Bartsch, 1942 - syn of: Cycladamsia seminuda (C.B. Adams, 1851) - (NEOCYCLOTIDAE)
- seminudata, Pictonia seminudata Buckman, 1924 † - (AULACOSTEPHANIDAE) (FOSSIL)
- seminudatus, Triozites seminudatus Buckman, 1924 † - syn of: Pictonia seminudata Buckman, 1924 † - (AMMONOIDEA (unassigned)) (FOSSIL)
- seminudum, Cerithium vetustum seminudum (W.H. Hudleston, 1882 †) - (CERITHIIDAE) (FOSSIL)
- seminudum, Ananias seminudum W.J. Gordon & E.L. Yochelson, 1983 † - (GOSSELETINIDAE) (FOSSIL)
- seminudum, Plagiostoma seminudum (Whidborne) † - (LIMIDAE) (FOSSIL)
- seminudum, Farcimen seminudum (F. Poey, 1854) - (MEGALOMASTOMIDAE)
- seminudum aguayoi, Farcimen seminudum aguayoi L.O. Alcalde, 1945 - (MEGALOMASTOMIDAE)
- seminudum callare, Farcimen seminudum callare C. de la Torre & P. Bartsch, 1942 ex F. Poey MS - (MEGALOMASTOMIDAE)
- seminudum citrinum, Farcimen seminudum citrinum L.O. Alcalde, 1945 - (MEGALOMASTOMIDAE)
- seminudum culminis, Farcimen seminudum culminis L.O. Alcalde, 1945 - (MEGALOMASTOMIDAE)
- seminudum leani, Farcimen seminudum leani C. de la Torre & P. Bartsch, 1942 - (MEGALOMASTOMIDAE)
- seminudum leoni, Farcimen seminudum leoni C. de la Torre, P. Bartsch & J.P.E. Morrison, 1942 - (MEGALOMASTOMIDAE)
- seminudum paeyi, Farcimen seminudum paeyi C. de la Torre & P. Bartsch, 1942 - (MEGALOMASTOMIDAE)
- seminudum protactum, Farcimen seminudum protactum L.O. Alcalde, 1945 - (MEGALOMASTOMIDAE)
- seminudus, Dictyoconites seminudus Mojsisovics, 1902 † - (AULACOCERATIDAE) (FOSSIL)
- seminudus, Rhinoclavis seminudus G.B. II Sowerby in L.A. Reeve, 1865 - syn of: Rhinoclavis articulata (A. Adams & L.A. Reeve, 1850) - (CERITHIIDAE)
- seminudus, Cyrtulus seminudus Noetling, 1901 † - (FASCIOLARIIDAE) (FOSSIL)
- seminudus, Musculus seminudus G.P. Deshayes, 1830 † - (MYTILIDAE) (FOSSIL)
- seminudus, Tirolites seminudus Mojsisovics, 1882 † - syn of: Tirolites idrianus (J. Von Hauer, 1865 †) - (TIROLITIDAE) (FOSSIL)
- seminudus, Solariorbis seminudus (C.B. Adams, 1852) - (TORNIDAE)
- seminula, Radomaniola seminula (G.R. von Frauenfeld, 1863) - (HYDROBIIDAE)
- seminula, Turcorientalia seminula (G.R. von Frauenfeld, 1863) - syn of: Radomaniola seminula (G.R. von Frauenfeld, 1863) - (HYDROBIIDAE)
- seminula, Lucina seminula Gould, 1862 - syn of: Cardiolucina rugosa (C. Hedley, 1909) - (LUCINIDAE)
- seminula, Prunum seminula W.H. Dall, 1881 - syn of: Prunum abyssorum (J.R. le B. Tomlin, 1916) - (MARGINELLIDAE)
- seminula, Marginella seminula W.H. Dall, 1881 - syn of: Prunum abyssorum (J.R. le B. Tomlin, 1916) - (MARGINELLIDAE)
- seminulum, Pisinna seminulum (T.A. de M. Monterosato, 1877) - (ANABATHRIDAE)
- seminulum, Barleeia seminulum (T.A. de M. Monterosato, 1877) - (BARLEEIIDAE)
- seminulum, Zafra seminulum (K.H.J. Thiele, 1925) - (COLUMBELLIDAE)
- seminulum, Corbulomya seminulum G.P. Deshayes, 1857 † - (CORBULIDAE) (FOSSIL)
- seminulum, Cyrtolites seminulum J. Perner, 1903 † - (CYRTOLITIDAE) (FOSSIL)
- seminulum, Bornia seminulum R.A. Philippi, 1836 - syn of: Lasaea adansoni W.H. Dall, 1899 - (KELLIIDAE)
- seminulum, Bornia seminulum R.A. Philippi, 1836 - syn of: Lasaea adansoni W.H. Dall, 1899 - (KELLIIDAE)
- seminulum, Parvilucina seminulum (G.P. Deshayes, 1857 †) - (LUCINIDAE) (FOSSIL)
- seminulum, Ovulum seminulum G.B. II Sowerby, 1828 - syn of: Simnia avena (G.B. II Sowerby, 1832) - (OVULIDAE)
- seminulum, Rissoa seminulum T.A. de M. Monterosato, 1877 - syn of: Barleeia seminulum (T.A. de M. Monterosato, 1877) - (RISSOIDAE)
- seminulum, Staurodon seminulum (R.T. Lowe, 1852) - (VERTIGINIDAE)
- seminulum, Vertigo seminulum C.A. Westerlund, 1871 - syn of: Vertigo antivertigo J.P.R. Draparnaud, 1801 - (VERTIGINIDAE)
- seminulum, Nesopupa newcombi seminulum (O. Böttger) - (VERTIGINIDAE)
- seminummuarius, Mytilus seminummuarius H. Guo, 1985 † - (MYTILIDAE) (FOSSIL)
- semiobliterata, Dosinia semiobliterata G.P. Deshayes, 1853 - (VENERIDAE)
- semiobsoletus, Purpuriconus symmetricus semiobsoletus (C.J. Maury, 1917 †) - (CONIDAE) (FOSSIL)
- semiorbicularis, Promytilus semiorbicularis Y. Fang, 1987 † - (MYTILIDAE) (FOSSIL)
- semiorbiculata, Beguina semiorbiculata (C. Linnaeus, 1758) - (CARDITIDAE)
- semiorbiculata, Chama semiorbiculata C. Linnaeus, 1758 - syn of: Beguina semiorbiculata (C. Linnaeus, 1758) - (CHAMIDAE)
- semiornata, Crosseola semiornata (R. Tate, 1893 †) - (CROSSEOLIDAE) (FOSSIL)
- semiornata, Nucula semiornata A.V.M.D. D'Orbigny, 1842 - (NUCULIDAE)
- semiornata, Nucula semiornata Del Rio, 1992 - syn of: Ennucula puelcha (A.V.M.D. D'Orbigny, 1842) - (NUCULIDAE)
- semiornata, Nucula semiornata d'Orbigny, 1846 - syn of: Nucula semiornata A.V.M.D. D'Orbigny, 1842 - (NUCULIDAE)
- semiornata, Lamellinucula semiornata d'Orbigny, 1842 - syn of: Nucula semiornata A.V.M.D. D'Orbigny, 1842 - (NUCULIDAE)
- semiornata, Platyclymenia semiornata Petter, 1960 † - syn of: Platyclymenia annulata (G.G. Münster, 1832 †) - (PLATYCLYMENIIDAE) (FOSSIL)
- semiornata, Cyclostomaria semiornata (F. Stoliczka in Laube, 1867 †) - (PLEUROTOMARIIDAE) (FOSSIL)
- semiornata, Microschiza semiornata (G.A. Goldfuss, 1844 †) - (PSEUDOMELANIIDAE) (FOSSIL)
- semiornata, Barroisocaulus semiornata (Spitz, 1907 †) - (PTYCHOCAULIDAE) (FOSSIL)
- semiornata, Evalea semiornata L. de Folin, 1872 - syn of: Ondina warreni (W. Thompson, 1845) - (PYRAMIDELLIDAE)
- semiornata, Hypsipleura semiornata E.A.L. Kittl, 1894 † - (ZYGOPLEURIDAE) (FOSSIL)
- semiornatum, Proacirsa semiornatum (Greppin, 1888 †) - (GORDENELLIDAE) (FOSSIL)
- semiornatum, Orthonema semiornatum Anderson & al., 1985 † - (ORTHONEMATIDAE) (FOSSIL)
- semiornatum, Placenticeras semiornatum (A.V.M.D. D'Orbigny, 1850 †) - (PLACENTICERATIDAE) (FOSSIL)
- semiornatus, Ammonites semiornatus A.V.M.D. D'Orbigny, 1850 † - syn of: Placenticeras semiornatum (A.V.M.D. D'Orbigny, 1850 †) - (AMMONITIDA (unassigned)) (FOSSIL)
- semiornatus, Amphithalamus semiornatus (C.R. Laws, 1948 †) - (ANABATHRIDAE) (FOSSIL)
- semiornatus, Cenoceras semiornatus (Crick, 1898 †) - (CENOCERATIDAE) (FOSSIL)
- semiornatus, Nautilus semiornatus Crick, 1898 † - syn of: Cenoceras semiornatus (Crick, 1898 †) - (NAUTILIDAE) (FOSSIL)
- semiornatus, Pseudotoites semiornatus (Crick, 1894 †) - (OTOITIDAE) (FOSSIL)
- Semiornites, Genus Semiornites Arthaber, 1912 † (CERATITIDAE) (FOSSIL)
- Semipallium, Genus Semipallium É. Lamy, 1928 (PECTINIDAE)
- semipalmatus, Octopus semipalmatus R. Owen, 1836 - syn of: Tremoctopus violaceus S. Delle Chiaje, 1830 - (OCTOPODIDAE)
- semiparadoxa, Soliclymenia semiparadoxa Schindewolf, 1937 † - (GLATZIELLIDAE) (FOSSIL)
- semipartita, Xesta semipartita (A.E.J. Férussac, 1820) - (ARIOPHANTIDAE)
- semipartitus, Discoceratites semipartitus (P.D. Montfort, 1802 †) - (CERATITIDAE) (FOSSIL)
- semipatula, Ampullina semipatula G.P. Deshayes, 1864 † - (AMPULLINIDAE) (FOSSIL)
- semipecten, Erycinopsis semipecten (Cossmann) † - (LASAEIDAE) (FOSSIL)
- Semipecten, syn of: Genus Hemipecten A. Adams & L.A. Reeve, 1849 (PECTINIDAE)
- semipellucida, Nipponaphera semipellucida (A. Adams & L.A. Reeve, 1850) - (CANCELLARIIDAE)
- semipellucida, Cancellaria semipellucida A. Adams & L.A. Reeve, 1850 - syn of: Nipponaphera semipellucida (A. Adams & L.A. Reeve, 1850) - (CANCELLARIIDAE)
- semipellucida, Monodacna semipellucida (B.M. Logvinenko & Y.I. Starobogatov, 1967) - (CARDIIDAE)
- semipellucida, Hypanis semipellucida B.M. Logvinenko & Y.I. Starobogatov, 1967 - syn of: Monodacna semipellucida (B.M. Logvinenko & Y.I. Starobogatov, 1967) - (CARDIIDAE)
- semipellucida, Pseudoneaera semipellucida (J.T. Kuroda, 1948) - (CUSPIDARIIDAE)
- semipellucida, Cymatosyrinx semipellucida (E.A. Smith, 1888) - (DRILLIIDAE)
- semipellucida, Alaba semipellucida (H.B. Preston, 1905) - (LITIOPIDAE)
- semipellucida, Reynellona semipellucida T. Kase, 1998 - (PICKWORTHIIDAE)
- semipellucida, Pseudosetia semipellucida (H.B.S. Friele, 1879) - (RISSOIDAE)
- semipellucidus, Mesembrinus semipellucidus H.B. Tristram, 1861 - (BULIMULIDAE)
- semiperfectus, Uniconocyclites semiperfectus Farsan, 1994 † - (UNICONOCYCLITIDAE) (FOSSIL)
- semiperlucidus, Joculator semiperlucidus A. Cecalupo & I. Perugia, 2013 - (CERITHIOPSIDAE)
- semipicta, Leptachatina semipicta E.R. Sykes, 1896 - (AMASTRIDAE)
- semipicta, Eburna semipicta G.B. II Sowerby, 1866 - syn of: Babylonia spirata (C. Linnaeus, 1758) - (ANCILLARIIDAE)
- semipicta, Babylonia semipicta G.B. II Sowerby, 1866 - syn of: Babylonia spirata (C. Linnaeus, 1758) - (BABYLONIIDAE)
- semipicta, Horologica semipicta (A.A. Gould, 1861) - (CERITHIOPSIDAE)
- semipicta, Pyreneola semipicta (G.B. III Sowerby, 1894) - (COLUMBELLIDAE)
- semipicta, Columbella semipicta G.B. III Sowerby, 1894 - syn of: Pyreneola semipicta (G.B. III Sowerby, 1894) - (COLUMBELLIDAE)
- semipicta, Helicella semipicta J.G. Hidalgo, 1870 - syn of: Helicella cistorum (P.M.A. Morelet, 1845) - (HYGROMIIDAE)
- semipictus, Plekocheilus semipictus J.G. Hidalgo, 1869 - (AMPHIBULIMIDAE)
- Semipirum, Genus Semipirum † (NEOGASTROPODA (UNASSIGNED)) (FOSSIL)
- semiplana, Hyotissa semiplana (J. de C. Sowerby) † - (GRYPHAEIDAE) (FOSSIL)
- semiplana, Ostrea semiplana Sowerby, 1825 † - (OSTREIDAE) (FOSSIL)
- semiplanata, Sanguinolaria semiplanata P.F. Röding, 1798 - syn of: Psammotella cruenta (J. Lightfoot, 1786) - (PSAMMOBIIDAE)
- semiplanata, Tellina semiplanata P.F. Röding, 1798 - syn of: Psammotella cruenta (J. Lightfoot, 1786) - (TELLINIDAE)
- semiplanus, Cirrus semiplanus Fischer & al., 2002 † - (CIRRIDAE) (FOSSIL)
- semiplanus, Poleumita semiplanus J. Perner, 1907 † - (EUOMPHALIDAE) (FOSSIL)
- semipleura, Nerita semipleura Twenhofel, 1940 † - syn of: Nerita marcouana Cragin, 1895 † - (NERITIDAE) (FOSSIL)
- semiplicata, Pisinna semiplicata (A.W.B. Powell, 1927) - (ANABATHRIDAE)
- semiplicata, Atomodesma semiplicata Reed, 1944 † - (ATOMODESMATIDAE) (FOSSIL)
- semiplicata, Kiaclymenia semiplicata Bogoslovsky, 1981 † - (BILOCLYMENIIDAE) (FOSSIL)
- semiplicata, Turricula semiplicata M.A. Peyrot, 1928 † - syn of: Costellaria semiplicata (M.A. Peyrot, 1928 †) - (CLAVATULIDAE) (FOSSIL)
- semiplicata, Clymenia semiplicata G.G. Münster, 1839 † - syn of: Clymenia laevigata (G.G. Münster, 1832 †) - (CLYMENIIDAE) (FOSSIL)
- semiplicata, Pyreneola semiplicata (G.B. III Sowerby, 1894) - (COLUMBELLIDAE)
- semiplicata, Costoanachis semiplicata (R.E.C. Stearns, 1873) - (COLUMBELLIDAE)
- semiplicata, Anachis semiplicata R.E.C. Stearns, 1873 - syn of: Costoanachis semiplicata (R.E.C. Stearns, 1873) - (COLUMBELLIDAE)
- semiplicata, Costellaria semiplicata (M.A. Peyrot, 1928 †) - (COSTELLARIIDAE) (FOSSIL)
- semiplicata, Pusia semiplicata W.J. Broderip, 1836 - syn of: Pusia microzonias (J.B.P.A. Lamarck, 1811) - (COSTELLARIIDAE)
- semiplicata, Auriculastra semiplicata (H. Adams & A. Adams, 1854) - (ELLOBIIDAE)
- semiplicata, Adkinsia semiplicata Böse, 1928 † - syn of: Adkinsia bosquensis Böse, 1928 † - (FLICKIIDAE) (FOSSIL)
- semiplicata, Odontomaria semiplicata (C.L.F. von Sandberger & C.L.F. von Sandberger, 1850 †) - (GOSSELETINIDAE) (FOSSIL)
- semiplicata, Haliotis semiplicata K.T. Menke, 1843 - (HALIOTIDAE)
- semiplicata, Belgrandia semiplicata H.D. Boeters & G. Falkner, 2009 - (HYDROBIIDAE)
- semiplicata, Papillocithara semiplicata R.N. Kilburn, 1992 - (MANGELIIDAE)
- semiplicata, Oenopota pyramidalis semiplicata G.O. Sars, 1878 - (MANGELIIDAE)
- semiplicata, Melanopsis semiplicata M. von Neumayr, 1880 † - (MELANOPSIDAE) (FOSSIL)
- semiplicata, Tiara semiplicata W.J. Broderip, 1836 - syn of: Pusia microzonias (J.B.P.A. Lamarck, 1811) - (MITRIDAE)
- semiplicata, Stramonita semiplicata G.J. Vermeij, 2001 † - (MURICIDAE) (FOSSIL)
- semiplicata, Bullia semiplicata (J.E. Gray, 1833) - (NASSARIIDAE)
- semiplicata, Nassa semiplicata C.B. Adams, 1853 - syn of: Nassarius fraterculus (R.W. Dunker, 1860) - (NASSARIIDAE)
- semiplicata, Ostrea semiplicata H.C. Küster, 1868 - syn of: Dendostrea sandvichensis (G.B. II Sowerby in L.A. Reeve, 1871) - (OSTREIDAE)
- semiplicata, Dendostrea semiplicata H.C. Küster, 1868 - syn of: Dendostrea sandvichensis (G.B. II Sowerby in L.A. Reeve, 1871) - (OSTREIDAE)
- semiplicata, Bulinus semiplicata P.M.A. Morelet, 1868 - syn of: Pyrgophysa forskalii (C.G. Ehrenberg, 1831) - (PLANORBIDAE)
- semiplicata, Posidonotis semiplicata (A. Hyatt, 1894 †) - (POSIDONIIDAE) (FOSSIL)
- semiplicata, Siogamaia semiplicata (Turton, 1932) - (PYRAMIDELLIDAE)
- semiplicata, Chrysallida semiplicata A. Adams, 1860 - (PYRAMIDELLIDAE)
- semiplicata, Rissoina semiplicata (J.B.P.A. Lamarck, 1804 †) - (RISSOINIDAE) (FOSSIL)
- semiplicata, Asthelys semiplicata B.A. Marshall, 1991 - (SEGUENZIIDAE)
- semiplicata, Vanikoro semiplicata W.H. Pease, 1861 - syn of: Vanikoro acuta C.A. Récluz, 1844 - (VANIKORIDAE)
- semiplicata, Chionopsis semiplicata (Nomland, 1917 †) - (VENERIDAE) (FOSSIL)
- semiplicata, Zebina semiplicata (W.H. Pease, 1863) - (ZEBINIDAE)
- semiplicata hiradoensis, Nassa semiplicata hiradoensis H.A. Pilsbry, 1904 - syn of: Nassarius fraterculus (R.W. Dunker, 1860) - (NASSARIIDAE)
- semiplicata hizenensis, Nassa semiplicata hizenensis H.A. Pilsbry, 1904 - syn of: Nassarius fraterculus (R.W. Dunker, 1860) - (NASSARIIDAE)
- semiplicatilis, Turbo semiplicatilis Klipstein, 1843 † - (TURBINIDAE) (FOSSIL)
- semiplicatoides, Zeuxis semiplicatoides S.P. Zhang & Z. You, 2007 - syn of: Nassarius foveolatus (R.W. Dunker, 1847) - (NASSARIIDAE)
- semiplicatum, Buccinum semiplicatum R.W. Dunker, 1853 - syn of: Nassarius gaudiosus (R.B. Hinds, 1844) - (BUCCINIDAE)
- semiplicatum, Buccinum semiplicatum A. da Costa, 1829 † - syn of: Tritia corniculum (A.G. Olivi, 1792 †) - (BUCCINIDAE) (FOSSIL)
- semiplicatum, Cymatopegma semiplicatum Pojeta & al., 1977 † - (RIBEIRIIDAE) (FOSSIL)
- semiplicatus, Cantharus semiplicatus G.P. Deshayes, 1834 † - (BUCCINIDAE) (FOSSIL)
- semiplicatus, Retifusus semiplicatus A.N. Golikov, 1985 - syn of: Retifusus parvus (R. Tiba, 1980) - (BUCCINIDAE)
- semiplicatus, Atlantica semiplicatus L. Pfeiffer, 1852 - syn of: Atlantica guerinianus (R.T. Lowe, 1852) - (DISCIDAE)
- semiplicatus, Nassarius semiplicatus A. Adams, 1852 - syn of: Nassarius sinarus (R.A. Philippi, 1851) - (NASSARIIDAE)
- semiplicatus, Zeuxis semiplicatus A. Adams, 1852 - syn of: Nassarius sinarus (R.A. Philippi, 1851) - (NASSARIIDAE)
- semiplicatus, Theodoxus semiplicatus (M. von Neumayr, 1875 †) - (NERITIDAE) (FOSSIL)
- semiplicatus, Unio semiplicatus H.C. Küster, 1862 - syn of: Medionidus acutissimus (I. Lea, 1831) - (UNIONIDAE)
- semiplicatus nigra, Theodoxus semiplicatus nigra E. Jekelius, 1932 † - (NERITIDAE) (FOSSIL)
- semiplota, Staphylaea semiplota (J.W. Mighels, 1845) - (CYPRAEIDAE)
- semiplota annae, Staphylaea semiplota annae (S.R. Roberts, 1869) - (CYPRAEIDAE)
- semiplumbeus, Trigonochlamys semiplumbeus O. Böttger, 1886 - syn of: Trigonochlamys imitatrix O. Böttger, 1881 - (TRIGONOCHLAMYDIDAE)
- semipolita, Cerion semipolita (C.J. Maynard & W.F. Clapp, 1920) - (CERIONIDAE)
- semipolita, Oospira semipolita A.R.J.B. Bavay & P. Dautzenberg, 1899 - (CLAUSILIIDAE)
- semipolita, Cochlespira pulchella semipolita A.W.B. Powell, 1969 - (COCHLESPIRIDAE)
- semipolita mansonensis, Oospira semipolita mansonensis (O.F. von Möllendorff, 1901) - (CLAUSILIIDAE)
- semipolitum, Dentalium semipolitum W.J. Broderip & G.B. I Sowerby, 1829 - syn of: Graptacme semistriata (W. Turton, 1819) - (DENTALIIDAE)
- semipolitum, Hildoceras semipolitum (Buckman, 1902 †) - (HILDOCERATIDAE) (FOSSIL)
- Semiporcellana, syn of: Genus Ovula J.G. Bruguière, 1789 (OVULIDAE)
- semipunctata, Columbella semipunctata J.B.P.A. Lamarck, 1822 - syn of: Pyrene punctata (J.G. Bruguière, 1789) - (COLUMBELLIDAE)
- semipunctata, Chrysallida semipunctata S. Nomura, 1937 - (PYRAMIDELLIDAE)
- semipunctata, Pitar semipunctata (T.A. Conrad, 1848 †) - (VENERIDAE) (FOSSIL)
- semipunctatus, Calliostoma semipunctatus A. Braun, 1841 † - syn of: Tylotrochus semipunctatus (A. Braun, 1841 †) - (CALLIOSTOMATIDAE) (FOSSIL)
- semipunctatus, Tylotrochus semipunctatus (A. Braun, 1841 †) - (PROCONULIDAE) (FOSSIL)
- semipunctatus, Trochus semipunctatus A. Braun, 1841 † - syn of: Tylotrochus semipunctatus (A. Braun, 1841 †) - (TROCHIDAE) (FOSSIL)
- semipunctus, Solariorbis semipunctus R.C. Moore, 1965 - (TORNIDAE)
- semipurpurata, Chama dunkeri semipurpurata C.E. Lischke - (CHAMIDAE)
- semipurpurea, Petricola semipurpurea R.W. Dunker, 1882 - syn of: Irus mitis (G.P. Deshayes, 1854) - (VENERIDAE)
- semipurpurea, Rupellaria semipurpurea R.W. Dunker, 1882 - syn of: Irus mitis (G.P. Deshayes, 1854) - (VENERIDAE)
- semiquadrivolvis, Chloritis semiquadrivolvis (E.C. Von Martens, 1903) - (CAMAENIDAE)
- semiradiata, Goniophorina semiradiata Isberg, 1934 † - (GONIOPHORINIDAE) (FOSSIL)
- semiradiata, Orthodesma semiradiata Reed, 1905 † - (MODIOMORPHIDAE) (FOSSIL)
- semiradiata, Montacuta semiradiata R. Tate, 1889 - (MONTACUTIDAE)
- semiradiata, Pinna semiradiata Author unknown † - (PINNIDAE) (FOSSIL)
- semiradiata neozelanica, Montacuta semiradiata neozelanica (R.K. Dell, 1956) - (MONTACUTIDAE)
- semiradiatus, Musculus semiradiatus (J.C. Verco, 1908) - (MYTILIDAE)
- semiramisensis, Nucula semiramisensis H.B. Preston, 1916 - syn of: Ennucula cumingii (R.B. Hinds, 1843) - (NUCULIDAE)
- Semiranella, syn of: Genus Sassia L.M.D. Bellardi, 1873 (RANELLIDAE)
- semiretia, Retites semiretia J.E. McCaleb, 1964 † - (RETICULOCERATIDAE) (FOSSIL)
- semireticosa, Nassa semireticosa Harmer, 1914 † - (MURICIDAE) (FOSSIL)
- semireticulata, Lucina semireticulata D'Orbigny, 1846 - syn of: Phlyctiderma semiaspera (R.A. Philippi, 1836) - (LUCINIDAE)
- semireticulata, Chrysallida semireticulata Sorgenfrei, 1958 † - (PYRAMIDELLIDAE) (FOSSIL)
- semireticulata, Pusillina semireticulata (R. Murdoch & H.H. Suter, 1906) - (RISSOIDAE)
- semireticulata, Haurakia semireticulata (R. Murdoch & H.H. Suter, 1906) - syn of: Pusillina semireticulata (R. Murdoch & H.H. Suter, 1906) - (RISSOIDAE)
- semireticulata, Solariella semireticulata (H.H. Suter, 1908) - (SOLARIELLIDAE)
- Semiretusa, Subgenus Retusa (Semiretusa) K.H.J. Thiele, 1925 † (RETUSIDAE) (FOSSIL)
- Semiricinula, Genus Semiricinula E.C. Von Martens, 1903 (MURICIDAE)
- semirita, Barbatia semirita Berezovsky, 2010 † - (ARCIDAE) (FOSSIL)
- Semirossia, Genus Semirossia J.J.S. Steenstrup, 1887 (SEPIOLIDAE)
- semirostrata, Cuspidaria semirostrata É.A.A. Locard, 1898 - (CUSPIDARIIDAE)
- semirostrata, Acila semirostrata Grant & H.R. Gale, 1931 - (NUCULIDAE)
- semirubida, Acmaea semirubida W.H. Dall, 1914 - syn of: Eoacmaea semirubida (W.H. Dall, 1914) - (ACMAEIDAE)
- semirubida, Eoacmaea semirubida (W.H. Dall, 1914) - (EOACMAEIDAE)
- semirubida, Lottia semirubida W.H. Dall, 1914 - syn of: Eoacmaea semirubida (W.H. Dall, 1914) - (LOTTIIDAE)
- semirubra, Patelloida semirubra W.H. Dall, 1914 - syn of: Eoacmaea pustulata (G.S. Helbling, 1779) - (LOTTIIDAE)
- semirubra, Tellimya semirubra (A. Gaglini, 1992) - (MONTACUTIDAE)
- semirugata, Cryptozona semirugata (H.H. Beck, 1837) - (ARIOPHANTIDAE)
- Semirugata, Subgenus Delima (Semirugata) O. Böttger, 1878 (CLAUSILIIDAE)
- semirugata, Delima semirugata (E.A. Rossmässler, 1836) - (CLAUSILIIDAE)
- semirugata, Paphia semirugata (R.A. Philippi, 1847) - (VENERIDAE)
- semirugata, Venus semirugata R.A. Philippi, 1847 - syn of: Paphia semirugata (R.A. Philippi, 1847) - (VENERIDAE)
- semirugata, Athleta semirugata (H.A. Rehder & C.S. Weaver, 1974) - (VOLUTIDAE)
- semirugata blaui, Delima semirugata blaui (O.F. von Möllendorff, 1873) - (CLAUSILIIDAE)
- semirugata obesa, Delima semirugata obesa (L. Pfeiffer, 1861) - (CLAUSILIIDAE)
- semirugata vibex, Delima semirugata vibex (E.A. Rossmässler, 1839) - (CLAUSILIIDAE)
- semirugatum, Cerithium semirugatum B. Wade, 1926 † - (CERITHIIDAE) (FOSSIL)
- semirugatum, Cerithiella semirugatum B. Wade, 1926 † - (NEWTONIELLIDAE) (FOSSIL)
- semirugatus, Unio semirugatus J.C. Chenu, 1858 - syn of: Parreysia corrugata (O.F. Müller, 1774) - (UNIONIDAE)
- semirugosa, Hennocquia semirugosa (Laube, 1867 †) - (ACMAEIDAE) (FOSSIL)
- semirugosa, Hygromia semirugosa (W. Kobelt) - (HYGROMIIDAE)
- semirugosa, Nerita semirugosa C.A. Récluz, 1841 - (NERITIDAE)
- semirugosa, Thracia semirugosa L.A. Reeve, 1859 - syn of: Cyathodonta rugosa (J.B.P.A. Lamarck, 1818) - (THRACIIDAE)
- semirugosa, Cyathodonta semirugosa L.A. Reeve, 1859 - syn of: Cyathodonta rugosa (J.B.P.A. Lamarck, 1818) - (THRACIIDAE)
- semirugosa, Diplodonta semirugosa (W.H. Dall, 1899) - (UNGULINIDAE)
- semirugosa, Phlyctiderma semirugosa W.H. Dall, 1899 - syn of: Diplodonta semirugosa (W.H. Dall, 1899) - (UNGULINIDAE)
- semirugosus, Sinuites semirugosus Reed, 1921 † - (SINUITIDAE) (FOSSIL)
- semirutum, Phacoceras semirutum Shimanskiy, 1967 † - (CENTROCERATIDAE) (FOSSIL)
- semisagitta, Pteria semisagitta J.B.P.A. Lamarck, 1819 - syn of: Pteria penguin (P.F. Röding, 1798) - (PTERIIDAE)
- Semisalsa, Genus Semisalsa P. Radoman, 1974 (COCHLIOPIDAE)
- semiscalaris, Rhiopoma semiscalaris F.G. Thompson, 1958 † - (TRUNCATELLIDAE) (FOSSIL)
- semisculpta, Achatina semisculpta L. Pfeiffer, 1845 - (ACHATINIDAE)
- semisculpta, Elaphroconcha semisculpta (E.C. Von Martens) - (ARIOPHANTIDAE)
- semisculpta, Stigmatica paestana semisculpta (M. Paulucci, 1878) - (CLAUSILIIDAE)
- semisculpta, Anachis semisculpta (G. Nevill & H. Nevill, 1875) - (COLUMBELLIDAE)
- semisculpta, Diplommatina semisculpta W.T. Blanford, 1868 - (DIPLOMMATINIDAE)
- semisculpta, Lepidotrichia semisculpta O.F. von Möllendorff - (HELICARIONIDAE)
- semisculpta, Mitra semisculpta A. Adams & L.A. Reeve, 1850 - syn of: Pusia semisculptum (A. Adams & L.A. Reeve, 1850) - (MITRIDAE)
- semisculpta, Cubasansonia semisculpta (J. Espinosa & R. Fernández-Garcés, 1990) - (PICKWORTHIIDAE)
- semisculpta, Odostomia semisculpta F. Lange de Morretes, 1949 - (PYRAMIDELLIDAE)
- semisculpta, Ringicula semisculpta C. Hedley, 1911 - (RINGICULIDAE)
- semisculpta, Porosalvania semisculpta S. Gofas, 2007 - (RISSOIDAE)
- semisculpta, Rissoina semisculpta R. Tate, 1899 - syn of: Rissoina antoni G. Schwartz, 1860 - (RISSOINIDAE)
- semisculpta, Solariella semisculpta E.C. Von Martens, 1904 - syn of: Spectamen semisculptum (E.C. Von Martens, 1904) - (SOLARIELLIDAE)
- semisculpta, Haplocion semisculpta (R.E.C. Stearns, 1890) - (UROCOPTIDAE)
- semisculpta, Scissileda semisculpta (K.H.J. Thiele & S.G.A. Jaeckel, 1931) - (YOLDIIDAE)
- semisculptum, Pusia semisculptum (A. Adams & L.A. Reeve, 1850) - (COSTELLARIIDAE)
- semisculptum, Ellobium semisculptum (H. Adams & A. Adams, 1854) - (ELLOBIIDAE)
- semisculptum, Auriculodes semisculptum H. Adams & A. Adams, 1854 - syn of: Ellobium semisculptum (H. Adams & A. Adams, 1854) - (ELLOBIIDAE)
- semisculptum, Cyclostrema semisculptum E.C. Von Martens, 1904 - syn of: Spectamen semisculptum (E.C. Von Martens, 1904) - (LIOTIIDAE)
- semisculptum, Spectamen semisculptum (E.C. Von Martens, 1904) - (SOLARIELLIDAE)
- semisculptum, Tubiola semisculptum E.C. Von Martens, 1904 - syn of: Spectamen semisculptum (E.C. Von Martens, 1904) - (VANIKORIDAE)
- semisculptus, Acteon semisculptus E.A. Smith, 1890 - (ACTEONIDAE)
- semisculptus, Onithochiton semisculptus H.A. Pilsbry, 1894 - syn of: Onithochiton neglectus A. de Rochebrune, 1881 - (CHITONIDAE)
- semisculptus, Circulus semisculptus (A.A. Olsson & J.T.L. McGinty, 1958) - (TORNIDAE)
- semisericata, Nipponochlamys semisericata (H.A. Pilsbry, 1902) - (HELICARIONIDAE)
- Semisinus, syn of: Genus Hemisinus W.J. Swainson, 1840 (THIARIDAE)
- Semisolarium, Genus Semisolarium Cossmann , 1915 † (TROCHIDAE) (FOSSIL)
- semisolutum, Opisthostoma semisolutum J.J. Vermeulen, 1994 - (DIPLOMMATINIDAE)
- semispinata, Sonninia semispinata Buckman † - (SONNINIIDAE) (FOSSIL)
- semispinosa, Melongena semispinosa G.F. Dollfus, 1887 - syn of: Melongena melongena (C. Linnaeus, 1758) - (MELONGENIDAE)
- semispiralis, Acteon semispiralis P. Marshall, 1917 † - (ACTEONIDAE) (FOSSIL)
- semisquamosa, Discotectonica semisquamosa (H.G. Bronn, 1831 †) - (ARCHITECTONICIDAE) (FOSSIL)
- semistriata, Ambonychinia semistriata Isberg, 1934 † - (AMBONYCHIIDAE) (FOSSIL)
- semistriata, Herilla bosniensis semistriata (Z. Frankenberger, 1916) - (CLAUSILIIDAE)
- semistriata, Clymenia semistriata G.G. Münster, 1839 † - syn of: Linguaclymenia similis (G.G. Münster, 1839 †) - (CLYMENIIDAE) (FOSSIL)
- semistriata, Corbicula semistriata (G.P. Deshayes 1831 †) - (CYRENIDAE) (FOSSIL)
- semistriata, Naticopsis semistriata (G.G. Münster, 1840 †) - (DELPHINULOPSIDAE) (FOSSIL)
- semistriata, Graptacme semistriata (W. Turton, 1819) - (DENTALIIDAE)
- semistriata, Diala semistriata (R.A. Philippi, 1849) - (DIALIDAE)
- semistriata, Stylifer semistriata G.B. Sowerby, 1878 - syn of: Microstelma semistriatum (A. Adams, 1878) - (EULIMIDAE)
- semistriata, Fasciolaria semistriata Sowerby, 1850 † - (FASCIOLARIIDAE) (FOSSIL)
- semistriata, Haliotis semistriata L.A. Reeve, 1846 - syn of: Haliotis varia C. Linnaeus, 1758 - (HALIOTIDAE)
- semistriata, Atys semistriata W.H. Pease, 1860 - (HAMINOEIDAE)
- semistriata, Weinkauffia semistriata E. Réquien, 1848 - syn of: Weinkauffia turgidula (E. Forbes, 1844) - (HAMINOEIDAE)
- semistriata, Helicina semistriata G.B. Sowerby, 1866 - syn of: Poenia lirata (L. Pfeiffer, 1847) - (HELICINIDAE)
- semistriata, Hydrobia semistriata (A.V.M.D. D'Orbigny, 1841) - (HYDROBIIDAE)
- semistriata, Alaba semistriata R.A. Philippi, 1849 - syn of: Diala semistriata (R.A. Philippi, 1849) - (LITIOPIDAE)
- semistriata, Mactra semistriata L.A. Reeve, 1854 - (MACTRIDAE)
- semistriata, Paolaura semistriata C. Smriglio & P. Mariottini, 2001 - (MARGINELLIDAE)
- semistriata, Dactyloteuthis semistriata Münster, 1830 † - (MEGATEUTHIDIDAE) (FOSSIL)
- semistriata, Cymatonota semistriata Ulrich, 1893 † - (MODIOMORPHIDAE) (FOSSIL)
- semistriata, Cryptomya semistriata (S.C.T. Hanley, 1842) - (MYIDAE)
- semistriata, Mya semistriata S.C.T. Hanley, 1842 - syn of: Cryptomya semistriata (S.C.T. Hanley, 1842) - (MYIDAE)
- semistriata, Natica semistriata G.G. Münster, 1840 † - syn of: Naticopsis semistriata (G.G. Münster, 1840 †) - (NATICIDAE) (FOSSIL)
- semistriata, Nuculana semistriata Wood, 1840 † - syn of: Yoldia semistriata (Wood, 1840 †) - (NUCULANIDAE) (FOSSIL)
- semistriata, Nucula semistriata R. Tate, 1886 † - (NUCULIDAE) (FOSSIL)
- semistriata, Nucula semistriata Wood, 1840 † - syn of: Yoldia semistriata (Wood, 1840 †) - (NUCULIDAE) (FOSSIL)
- semistriata, Olivella semistriata (J.E. Gray, 1839) - (OLIVELLIDAE)
- semistriata, Tricolia semistriata (J.B.P.A. Lamarck, 1804 †) - (PHASIANELLIDAE) (FOSSIL)
- semistriata, Pinna semistriata Terquem † - (PINNIDAE) (FOSSIL)
- semistriata, Cyclotopsis semistriata (G.B. Sowerby, 1843) - (POMATIIDAE)
- semistriata, Turbonilla semistriata (Wood, 1879 †) - (PYRAMIDELLIDAE) (FOSSIL)
- semistriata, Pyrgiscus semistriata (E. Saurin, 1962) - (PYRAMIDELLIDAE)
- semistriata, Ringicula semistriata A.V.M.D. D'Orbigny, 1842 - (RINGICULIDAE)
- semistriata, Crisilla semistriata (G. Montagu, 1808) - (RISSOIDAE)
- semistriata, Rissoa semistriata R.A. Philippi, 1849 - syn of: Diala semistriata (R.A. Philippi, 1849) - (RISSOIDAE)
- semistriata, Rissoina semistriata (J.B.P.A. Lamarck, 1804 †) - (RISSOINIDAE) (FOSSIL)
- semistriata, Roxania semistriata (G.P. Deshayes, 1824 †) - (SCAPHANDRIDAE) (FOSSIL)
- semistriata, Tetrentodon semistriata C.G. Aguayo, 1932 - (UROCOPTIDAE)
- semistriata, Torrecoptis semistriata C. de la Torre & P. Bartsch, 1972 - (UROCOPTIDAE)
- semistriata, Yoldiella semistriata (J.G. Jeffreys, 1879) - (YOLDIIDAE)
- semistriata, Yoldia semistriata (Wood, 1840 †) - (YOLDIIDAE) (FOSSIL)
- semistriata azorica, Nassa semistriata azorica P. Dautzenberg, 1889 - syn of: Nassarius recidivus (E.C. Von Martens, 1876) - (NASSARIIDAE)
- semistriata bulliaeformis, Nassa semistriata bulliaeformis W. Kobelt, 1878 - syn of: Nassarius recidivus (E.C. Von Martens, 1876) - (NASSARIIDAE)
- semistriata cabrierensis, Nassa semistriata cabrierensis P. Fischer & R. Tournouer, 1873 - syn of: Nassarius cabrierensis (P. Fischer & R. Tournouer, 1873) - (NASSARIIDAE)
- semistriata cornea, Nassa semistriata cornea É.A.A. Locard, 1887 † - syn of: Tritia ovoidea (É.A.A. Locard, 1886 †) - (NASSARIIDAE) (FOSSIL)
- semistriata costulata, Nassa semistriata costulata É.A.A. Locard, 1887 † - syn of: Tritia ovoidea (É.A.A. Locard, 1886 †) - (NASSARIIDAE) (FOSSIL)
- semistriata curta, Nassa semistriata curta É.A.A. Locard, 1887 † - syn of: Tritia ovoidea (É.A.A. Locard, 1886 †) - (NASSARIIDAE) (FOSSIL)
- semistriata infrasulcata, Diala semistriata infrasulcata G.B. Sowerby, 1892 - (DIALIDAE)
- semistriata minima, Crisilla semistriata minima F. Nordsieck, 1972 - (RISSOIDAE)
- semistriata mua, Atys semistriata mua H.A. Pilsbry, 1921 - syn of: Atys semistriata W.H. Pease, 1860 - (HAMINOEIDAE)
- semistriata pura, Rissoa semistriata pura J.G. Jeffreys, 1867 - syn of: Crisilla semistriata (G. Montagu, 1808) - (RISSOIDAE)
- semistriata recidiva, Nassa semistriata recidiva E.C. Von Martens, 1876 - syn of: Nassarius recidivus (E.C. Von Martens, 1876) - (NASSARIIDAE)
- semistriata stricta, Diala semistriata stricta T. Habe, 1960 - (DIALIDAE)
- semistriatum, Buccinum semistriatum G.B. Brocchi, 1814 † - syn of: Nassarius semistriatus (G.B. Brocchi, 1814 †) - (BUCCINIDAE) (FOSSIL)
- semistriatum, Cardium semistriatum G.P. Deshayes † - syn of: Nemocardium keenae Renard, 1994 † - (CARDIIDAE) (FOSSIL)
- semistriatum, Cenoceras semistriatum (A.V.M.D. D'Orbigny, 1843 †) - (CENOCERATIDAE) (FOSSIL)
- semistriatum, Lunulacardium semistriatum Münster, 1840 † - (LUNULACARDIIDAE) (FOSSIL)
- semistriatum, Phylloceras semistriatum (A.V.M.D. D'Orbigny, 1840 †) - (PHYLLOCERATIDAE) (FOSSIL)
- semistriatum, Hemisimoceras semistriatum Spath, 1925 † - (SIMOCERATIDAE) (FOSSIL)
- semistriatum, Leptopeas semistriatum (P.M.A. Morelet, 1851) - (SUBULINIDAE)
- semistriatum, Teinostoma semistriatum (A.V.M.D. D'Orbigny, 1842) - (TORNIDAE)
- semistriatum, Microstelma semistriatum (A. Adams, 1878) - (ZEBINIDAE)
- semistriatum mihi, Buccinum semistriatum mihi G.B. Brocchi, 1814 † - syn of: Nassarius semistriatus (G.B. Brocchi, 1814 †) - (BUCCINIDAE) (FOSSIL)
- semistriatus, Acteon semistriatus M. Glibert, 1952 - syn of: Acteon tornatilis (C. Linnaeus, 1758) - (ACTEONIDAE)
- semistriatus, Arcestes semistriatus Mojsisovics, 1875 † - (ARCESTIDAE) (FOSSIL)
- semistriatus, Dermatobranchus semistriatus K. Baba, 1949 - (ARMINIDAE)
- semistriatus, Drymaeus semistriatus F. Haas, 1955 - (BULIMULIDAE)
- semistriatus, Bulimus semistriatus P.M.A. Morelet, 1851 - syn of: Leptopeas semistriatum (P.M.A. Morelet, 1851) - (BULIMULIDAE)
- semistriatus, Planulites semistriatus G.G. Münster, 1832 † - syn of: Cymaclymenia striata (G.G. Münster, 1832 †) - (CLYMENIIDAE) (FOSSIL)
- semistriatus, Cryptoconus lineolatus semistriatus (G.P. Deshayes, 1834 †) - (CONIDAE) (FOSSIL)
- semistriatus, Donax semistriatus G.S. Poli, 1795 - (DONACIDAE)
- semistriatus, Brachidontes semistriatus C.F.F. von Krauss, 1848 - syn of: Brachidontes pharaonis (P. Fischer, 1870) - (MYTILIDAE)
- semistriatus, Nassarius semistriatus (G.B. Brocchi, 1814 †) - (NASSARIIDAE) (FOSSIL)
- semistriatus, Procalpurnus semistriatus (W.H. Pease, 1862) - (OVULIDAE)
- semistriatus, Terebralia semistriatus O.A.L. Mörch, 1852 - (POTAMIDIDAE)
- semistriatus, Trochus semistriatus D'Orbigny, 1842 - syn of: Teinostoma semistriatum (A.V.M.D. D'Orbigny, 1842) - (TROCHIDAE)
- semistriatus, Turbo semistriatus G. Montagu, 1808 - syn of: Crisilla semistriata (G. Montagu, 1808) - (TURBINIDAE)
- semistriatus clodiensis, Donax semistriatus clodiensis (T.A. de M. Monterosato, 1884) - (DONACIDAE)
- semistriatus rostrata, Donax semistriatus rostrata P. Fischer in E. Vassel, 1880 - syn of: Donax semistriatus G.S. Poli, 1795 - (DONACIDAE)
- semistrigata, Phengus fischeri semistrigata (W. Kobelt, 1916) - (BRADYBAENIDAE)
- semistrigosa, Rhinoclama semistrigosa (J.G. Jeffreys, 1882) - (CUSPIDARIIDAE)
- semistriolata, Graptacme semistriolata (L. Guilding, 1834) - (DENTALIIDAE)
- semistriolatum, Graptacme semistriolatum L. Guilding, 1834 - syn of: Graptacme semistriolata (L. Guilding, 1834) - (DENTALIIDAE)
- Semistylifer, Genus Semistylifer A.E.M. Cossmann, 1921 † (EULIMIDAE) (FOSSIL)
- semisuave, Calliostoma semisuave J.F. Quinn, 1992 - (CALLIOSTOMATIDAE)
- semisulcata, Pisinna semisulcata (F.W. Hutton, 1885) - (ANABATHRIDAE)
- semisulcata, Crassina semisulcata W.E. Leach in A. Ross, 1819 - syn of: Astarte borealis (H.C.F. Schumacher, 1817) - (ASTARTIDAE)
- semisulcata, Astarte semisulcata Moller, 1842 - syn of: Astarte crebrilirata G.B. II Sowerby, 1854 - (ASTARTIDAE)
- semisulcata, Burnupena semisulcata (J.B.P.A. Lamarck, 1818) - (BUCCINIDAE)
- semisulcata, Bulla semisulcata R.A. Philippi, 1836 - syn of: Retusa truncatula (J.G. Bruguière, 1792) - (BULLIDAE)
- semisulcata, Papyridea semisulcata (J.E. Gray, 1825) - (CARDIIDAE)
- semisulcata, Cardilia semisulcata (J.B.P.A. Lamarck, 1819) - (CARDILIIDAE)
- semisulcata, Clavagella semisulcata E. Forbes, 1846 † - (CLAVAGELLIDAE) (FOSSIL)
- semisulcata, Conus berghausi semisulcata F. Sacco, 1898 † - (CONIDAE) (FOSSIL)
- semisulcata, Cylichna semisulcata R.W. Dunker, 1882 - syn of: Liloa porcellana (A.A. Gould, 1859) - (CYLICHNIDAE)
- semisulcata, Corbicula semisulcata G.P. Deshayes, 1854 - syn of: Corbicula limosa (W.G. Maton, 1809) - (CYRENIDAE)
- semisulcata, Isocardia semisulcata J.B.P.A. Lamarck, 1819 - syn of: Cardilia semisulcata (J.B.P.A. Lamarck, 1819) - (GLOSSIDAE)
- semisulcata, Spisula semisulcata (J.B.P.A. Lamarck, 1805 †) - (MACTRIDAE) (FOSSIL)
- semisulcata, Mactra semisulcata G.P. Deshayes, 1854 - syn of: Mactra olorina R.A. Philippi, 1846 - (MACTRIDAE)
- semisulcata, Lutraria semisulcata L.A. Reeve, 1854 - syn of: Mactra deshayesi L.A. Reeve, 1854 - (MACTRIDAE)
- semisulcata, Melanopsis excoriata semisulcata P.M. Pallary, 1920 - (MELANOPSIDAE)
- semisulcata, Haasica semisulcata (C.B. Adams, 1870) - (MYCETOPODIDAE)
- semisulcata, Tugonia semisulcata H. Adams & A. Adams, 1856 - syn of: Tugonia nobilis H. Adams & A. Adams, 1856 - (MYIDAE)
- semisulcata, Nassa semisulcata R.W. Dunker, 1867 - syn of: Nassarius gaudiosus (R.B. Hinds, 1844) - (NASSARIIDAE)
- semisulcata, Nassa semisulcata J.B. Hombron & C.H. Jacquinot, 1848 - syn of: Nassarius semisulcatus (J.B. Hombron & C.H. Jacquinot, 1848) - (NASSARIIDAE)
- semisulcata, Sigatica semisulcata (Gray, 1839) - (NATICIDAE)
- semisulcata, Leda semisulcata A. Adams, 1856 - syn of: Yoldia lata (R.B. Hinds, 1843) - (NUCULANIDAE)
- semisulcata, Olivina semisulcata J.E. Gray, 1858 - syn of: Olivella semistriata (J.E. Gray, 1839) - (OLIVELLIDAE)
- semisulcata, Pinna semisulcata R. Tate, 1886 † - (PINNIDAE) (FOSSIL)
- semisulcata, Neocraspedites semisulcata (A. von Koenen, 1902 †) - (POLYPTYCHITIDAE) (FOSSIL)
- semisulcata, Retusa semisulcata R.A. Philippi, 1836 - syn of: Retusa truncatula (J.G. Bruguière, 1792) - (RETUSIDAE)
- semisulcata, Vitrinella semisulcata A. Issel, 1869 - (TORNIDAE)
- semisulcata, Meroena semisulcata (J.B.P.A. Lamarck, 1806 †) - (VENERIDAE) (FOSSIL)
- semisulcata, Callista semisulcata (G.B. Sowerby, 1851) - (VENERIDAE)
- semisulcata bathyora, Sigatica semisulcata bathyora (W.P. Woodring, 1928 ) - (NATICIDAE)
- semisulcata holographa, Sigatica semisulcata holographa J.T.L. McGinty, 1940 - syn of: Sigatica carolinensis W.H. Dall, 1889 - (NATICIDAE)
- semisulcata leves, Spisula semisulcata leves A.V.M.D. D'Orbigny, 1850 † - (MACTRIDAE) (FOSSIL)
- semisulcata placenta, Astarte semisulcata placenta O.A.L. Mörch, 1869 - syn of: Astarte borealis (H.C.F. Schumacher, 1817) - (ASTARTIDAE)
- Semisulcatoceras, Subgenus Ptychophylloceras (Semisulcatoceras) Joly, 2000 † (PHYLLOCERATIDAE) (FOSSIL)
- semisulcatum, Cardium semisulcatum J.E. Gray, 1825 - syn of: Papyridea semisulcata (J.E. Gray, 1825) - (CARDIIDAE)
- semisulcatum, Semisulcatoceras semisulcatum (A.V.M.D. D'Orbigny, 1842 †) - (PHYLLOCERATIDAE) (FOSSIL)
- semisulcatus, Conus semisulcatus G.B. II Sowerby, 1870 - syn of: Kioconus capreolus (D. Röckel, 1985) - (CONIDAE)
- semisulcatus, Litostylus semisulcatus (G.B. Sowerby, 1843) - (CYCLOPHORIDAE)
- semisulcatus, Donax semisulcatus S.C.T. Hanley, 1843 - (DONACIDAE)
- semisulcatus, Melampus semisulcatus A. Mousson, 1869 - (ELLOBIIDAE)
- semisulcatus, Nassarius semisulcatus (J.B. Hombron & C.H. Jacquinot, 1848) - (NASSARIIDAE)
- semisulcatus, Turbonitella semisulcatus (B. Phillips, 1836 †) - (NERITOPSIDAE) (FOSSIL)
- Semisulcospira, Genus Semisulcospira O. Böttger, 1886 (SEMISULCOSPIRIDAE)
- SEMISULCOSPIRIDAE Morrison, 1952 - Family (GASTROPODA-CAENOGASTROPODA [Subclass]-CERITHIOIDEA [Superfamily])
- semisurrectus, Thylaeodus semisurrectus (Ant. Bivona-Bernardi, 1832) - (VERMETIDAE)
- semisurrectus antecedens, Thylaeodus semisurrectus antecedens A.E.M. Cossmann & M.A. Peyrot, 1922 † - (VERMETIDAE) (FOSSIL)
- semisurrectus minor, Vermetus semisurrectus minor T.A. de M. Monterosato, 1892 - syn of: Thylaeodus semisurrectus (Ant. Bivona-Bernardi, 1832) - (VERMETIDAE)
- semisurrectus typica, Vermetus semisurrectus typica T.A. de M. Monterosato, 1892 - syn of: Thylaeodus semisurrectus (Ant. Bivona-Bernardi, 1832) - (VERMETIDAE)
- semitarum, Achatina semitarum P.C.A.S.L. Rang, 1842 - syn of: Varicella semitarum (P.C.A.S.L. Rang, 1842) - (ACHATINIDAE)
- semitarum, Varicella semitarum (P.C.A.S.L. Rang, 1842) - (OLEACINIDAE)
- semitarum, Laevaricella semitarum (L. Pfeiffer, 1842) - (OLEACINIDAE)
- semitecta, Pomacea semitecta (A. Mousson, 1873) - (AMPULLARIIDAE)
- semitecta, Hemicycla semitecta A. Mousson, 1872 - (HELICIDAE)
- semitecta, Heterostoma semitecta J.D.W. Hartmann, 1843 - syn of: Heterostoma paupercula (R.T. Lowe, 1831) - (HYGROMIIDAE)
- semitectum, Pratulum semitectum (J. Marwick, 1926 †) - (CARDIIDAE) (FOSSIL)
- semitectus, Limax semitectus O.A.L. Mörch, 1857 - syn of: Deroceras laeve (O.F. Müller, 1774) - (LIMACIDAE)
- Semiterebellum, Genus Semiterebellum Cossmann † (ROSTELLARIIDAE) (FOSSIL)
- semiteres, Saccella semiteres (F.W. Hutton, 1877 †) - (NUCULANIDAE) (FOSSIL)
- semitessellatus, Bulimus semitessellatus L.J. Morlet, 1885 - syn of: Amphidromus semitessellatus (L.J. Morlet, 1885) - (BULIMULIDAE)
- semitessellatus, Amphidromus semitessellatus (L.J. Morlet, 1885) - (CAMAENIDAE)
- semitexta, Nassa semitexta C. Hedley, 1899 - syn of: Stosicia bourguignati (A. Issel, 1869) - (MURICIDAE)
- semitexta, Herouvalia semitexta (A.E.M. Cossmann, 1886 †) - (TELLINIDAE) (FOSSIL)
- semitexta, Stosicia semitexta C. Hedley, 1899 - (ZEBINIDAE)
- semiticum, Vexillum semiticum (C.F. Jickeli, 1874) - (COSTELLARIIDAE)
- semitornatus, Cladiscites semitornatus Mojsisovics, 1902 † - (CLADISCITIDAE) (FOSSIL)
- semitorta, Trisidos semitorta (J.B.P.A. Lamarck, 1819) - (ARCIDAE)
- semitorta, Arca semitorta J.B.P.A. Lamarck, 1819 - syn of: Trisidos semitorta (J.B.P.A. Lamarck, 1819) - (ARCIDAE)
- semitorta, Gervillella semitorta Cox & Arkell † - (BAKEVELLIIDAE) (FOSSIL)
- semitorta, Eulima semitorta A. Adams, 1861 - (EULIMIDAE)
- semitorta, Sassia semitorta J.T. Kuroda & T. Habe, 1961 - (RANELLIDAE)
- semitorta, Cadella semitorta (G.B. Sowerby, 1867) - (TELLINIDAE)
- semitorta torta, Trisidos semitorta torta O.A.L. Mörch, 1850 - syn of: Trisidos torta (O.A.L. Mörch, 1850) - (ARCIDAE)
- semitrachea, Caecum semitrachea Š. Brusina, 1865 - syn of: Caecum clarkii P.P. Carpenter, 1859 - (CAECIDAE)
- semitracheata, Plagioglypta semitracheata M. Boissevain, 1906 - (DENTALIIDAE)
- semitracheatum, Calliodentalium semitracheatum (M. Boissevain, 1906) - (CALLIODENTALIIDAE)
- semitracheum, Caecum semitracheum T.A. de M. Monterosato, 1884 - syn of: Caecum clarkii P.P. Carpenter, 1859 - (CAECIDAE)
- semitrisulcatus, Terebralia semitrisulcatus G.W. Tryon, 1887 - syn of: Terebralia sulcata (I. von Born, 1778) - (POTAMIDIDAE)
- Semitriton, Genus Semitriton A.E.M. Cossmann, 1903 (CANCELLARIIDAE)
- Semitrivia, Genus Semitrivia A.E.M. Cossmann, 1930 (TRIVIIDAE)
- Semitrochatella, Subgenus Eutrochatella (Semitrochatella) C.G. Aguayo & M.L. Jaume, 1958 (HELICINIDAE)
- semitruncata, Deceptrix semitruncata (Portlock, 1843 †) - (CARDIOLARIIDAE) (FOSSIL)
- semituberculata, Tryonia semituberculata Nuttall, 1990 † - (COCHLIOPIDAE) (FOSSIL)
- semituberculata, Peronia semituberculata H.M.D. de Blainville, 1825 - syn of: Onchidium planatum J.R.C. Quoy & J.P. Gaimard, 1824 - (ONCHIDIIDAE)
- semituberculata, Onchidium semituberculata H.M.D. de Blainville, 1825 - syn of: Onchidium planatum J.R.C. Quoy & J.P. Gaimard, 1824 - (ONCHIDIIDAE)
- semituberculatus, Imerites semituberculatus Rouchadze, 1933 † - syn of: Paraimerites semituberculatus (Rouchadze, 1933 †) - (HEMIHOPLITIDAE) (FOSSIL)
- semituberculatus, Imerites semituberculatus Rouchadzé, 1933 † - syn of: Calanquites semituberculatus (Rouchadzé, 1933 †) - (HEMIHOPLITIDAE) (FOSSIL)
- semituberculatus, Paraimerites semituberculatus (Rouchadze, 1933 †) - (HETEROCERATIDAE) (FOSSIL)
- semituberculatus, Calanquites semituberculatus (Rouchadzé, 1933 †) - (HETEROCERATIDAE) (FOSSIL)
- Semitubina, Genus Semitubina Cossmann, 1918 † (TUBINIDAE) (FOSSIL)
- Semiturriamarginella, syn of: Genus Marginella J.B.P.A. Lamarck, 1799 (MARGINELLIDAE)
- Semityphis, Genus Semityphis Martin, 1931 † (MURICIDAE) (FOSSIL)
- semiundata, Posidonia semiundata H. Guo, 1985 † - (POSIDONIIDAE) (FOSSIL)
- semiundulata, Eotrigonia semiundulata (B.W. Jenkins, 1865 †) - (TRIGONIIDAE) (FOSSIL)
- semiundulata granosa, Eotrigonia semiundulata granosa (G.B. Pritchard, 1903 †) - (TRIGONIIDAE) (FOSSIL)
- semiundulata lutosa, Eotrigonia semiundulata lutosa (G.B. Pritchard, 1903 †) - (TRIGONIIDAE) (FOSSIL)
- semiusta, Mitra semiusta S.S. Berry, 1957 - syn of: Mitra idae J.C. Melvill, 1893 - (MITRIDAE)
- semiusta, Bullia semiusta L.A. Reeve, 1846 - syn of: Bullia digitalis (L.W. Dillwyn, 1817) - (NASSARIIDAE)
- semiustus, Vanitrochus semiustus (P. Fischer, 1879) - (TROCHIDAE)
- semivaricosa, Opalia semivaricosa M.E.A. de Boury, 1889 - syn of: Opalia pumilio (O.A.L. Mörch, 1875) - (EPITONIIDAE)
- semivaricosa, Daphnella semivaricosa T. Habe & O. Masuda, 1990 - (RAPHITOMIDAE)
- semivelatus, Conus semivelatus G.B. III Sowerby, 1882 - syn of: Rhizoconus rattus (C.H. Hwass in J.G. Bruguière, 1792) - (CONIDAE)
- semiventula, Laminella citrina semiventula F. Borcherding, 1906 - (AMASTRIDAE)
- Semivertagus, syn of: Genus Rhinoclavis W.J. Swainson, 1840 (CERITHIIDAE)
- semivestita, Laminella venusta semivestita A. Hyatt & H.A. Pilsbry, 1911 - (AMASTRIDAE)
- semivestita, Modiolus semivestita R.W. Dunker, 1871 - syn of: Xenostrobus inconstans (R.W. Dunker, 1856) - (MYTILIDAE)
- semivestitum, Fissidentalium semivestitum (É.A.A. Locard, 1897) - (DENTALIIDAE)
- semivestitum, Farcimen ungula semivestitum C. de la Torre & P. Bartsch, 1942 - (MEGALOMASTOMIDAE)
- semiviatus, Leislingites semiviatus Tozer, 1994 † - (THETIDITIDAE) (FOSSIL)
- Semizona, Genus Semizona Ebbestad & Peel, 2001 † (EOTOMARIIDAE) (FOSSIL)
- semizonata, Cithara semizonata R.P.J. Hervier, 1897 - syn of: Eucithara coronata (R.B. Hinds, 1843) - (MANGELIIDAE)
- semizonata, Eucithara semizonata R.P.J. Hervier, 1897 - syn of: Eucithara coronata (R.B. Hinds, 1843) - (MANGELIIDAE)
- semlikiensis, Thapsia cinnamomeozonata semlikiensis H.A. Pilsbry, 1919 - (UROCYCLIDAE)
- semlini, Entolium semlini Crickmay, 1930 † - syn of: Entolium corneolum (A.T. Young & Bird, 1828 †) - (ENTOLIIDAE) (FOSSIL)
- semmelincki, Oliva semmelincki M.M. Schepman, 1891 - syn of: Oliva semmelinki M.M. Schepman, 1891 - (OLIVIDAE)
- semmelinki, Coccoderma semmelinki W.J.M. Maassen, 2002 - (ENIDAE)
- semmelinki, Oliva semmelinki M.M. Schepman, 1891 - (OLIVIDAE)
- semmelinki, Psammotellina semmelinki E.C. Von Martens, 1897 - syn of: Gari crassula (G.P. Deshayes, 1855) - (PSAMMOBIIDAE)
- semmelinki, Contradens semmelinki (E.C. Von Martens, 1891) - (UNIONIDAE)
- semmelinki borneensis, Psammotellina semmelinki borneensis E.C. Von Martens, 1897 - syn of: Gari crassula (G.P. Deshayes, 1855) - (PSAMMOBIIDAE)
- semmelinki fultoni, Contradens semmelinki fultoni F. Haas, 1930 - syn of: Contradens semmelinki (E.C. Von Martens, 1891) - (UNIONIDAE)
- semmelinki ouini, Oliva semmelinki ouini Y.I. Kantor & B. Tursch, 1998 - syn of: Oliva ouini Y.I. Kantor & B. Tursch, 1998 - (OLIVIDAE)
- semmelinki strubelli, Psammotellina semmelinki strubelli E.C. Von Martens, 1897 - syn of: Gari crassula (G.P. Deshayes, 1855) - (PSAMMOBIIDAE)
- semoni, Thularion semoni (E.C. Von Martens, 1894) - (HELICARIONIDAE)
- semoni, Pseudopotamis semoni E.C. Von Martens, 1894 - (PACHYCHILIDAE)
- semoni, Spathoteredo semoni C.E. von Moll, 1929 - syn of: Spathoteredo obtusa (P.B. Sivickis, 1928) - (TEREDINIDAE)
- semoni, Teredo semoni C.E. von Moll, 1929 - syn of: Spathoteredo obtusa (P.B. Sivickis, 1928) - (TEREDINIDAE)
- semota, Narona semota P.O. Jung, 1969 † - (CANCELLARIIDAE) (FOSSIL)
- Semotrachia, Genus Semotrachia T. Iredale, 1933 (CAMAENIDAE)
- Semparella, syn of: Genus Semperoncis Y.I. Starobogatov, 1976 (ONCHIDIIDAE)
- Semperdon, Genus Semperdon G.A. Solem, 1983 (CHAROPIDAE)
- semperi, Plekocheilus semperi W.L.H. Dohrn, 1882 - (AMPHIBULIMIDAE)
- semperi, Pomacea semperi (W. Kobelt, 1914) - (AMPULLARIIDAE)
- semperi, Armina semperi (L.S.R. Bergh, 1866) - (ARMINIDAE)
- semperi, Paludinella semperi K.H.J. Thiele, 1927 - (ASSIMINEIDAE)
- semperi, Bornella semperi J.C.H. Crosse, 1875 - syn of: Bornella stellifer (A. Adams & L.A. Reeve in A. Adams, 1848) - (BORNELLIDAE)
- semperi, Calocochlia semperi O.F. von Möllendorff, 1893 - (BRADYBAENIDAE)
- semperi, Hypselodoris semperi L.S.R. Bergh, 1877 - syn of: Hypselodoris infucata (W.P.E.S. Rüppell & F.S. Leuckart, 1830) - (CHROMODORIDIDAE)
- semperi, Ryssota semperi P. Bartsch, 1939 - (CHRONIDAE)
- semperi, Cirsochilus semperi (G.P. Deshayes, 1863 †) - (COLLONIIDAE) (FOSSIL)
- semperi, Conus semperi Speyer, 1862 † - (CONIDAE) (FOSSIL)
- semperi, Cyclophorus semperi W. Kobelt, 1886 - (CYCLOPHORIDAE)
- semperi, Dendrodoris semperi L.S.R. Bergh, 1876 - (DENDRODORIDIDAE)
- semperi, Drillia semperi A. von Koenen † - (DRILLIIDAE) (FOSSIL)
- semperi, Pteraeolidia semperi L.S.R. Bergh, 1870 - syn of: Pteraeolidia ianthina (G.F. Angas, 1864) - (FACELINIDAE)
- semperi, Flabellina semperi L.S.R. Bergh, 1870 - syn of: Pteraeolidia ianthina (G.F. Angas, 1864) - (FLABELLINIDAE)
- semperi, Hemiglypta semperi O.F. von Möllendorff - (HELICARIONIDAE)
- semperi, Melanopsis semperi C. De Stefani, 1877 † - (MELANOPSIDAE) (FOSSIL)
- semperi, Mitra semperi G.T. Poppe, S.P. Tagaro & R. Salisbury, 2009 - (MITRIDAE)
- semperi, Devonia semperi (K. Oshima, 1930) - (MONTACUTIDAE)
- semperi, Curvemysella semperi (Jenkins 1863) † - (MONTACUTIDAE) (FOSSIL)
- semperi, Platevindex semperi (H.P. Plate, 1893) - (ONCHIDIIDAE)
- semperi, Oncis semperi H.P. Plate, 1893 - syn of: Platevindex semperi (H.P. Plate, 1893) - (ONCHIDIIDAE)
- semperi, Prosimnia semperi (H.C. Weinkauff, 1881) - (OVULIDAE)
- semperi, Ovula semperi H.C. Weinkauff, 1881 - syn of: Prosimnia semperi (H.C. Weinkauff, 1881) - (OVULIDAE)
- semperi, Euselenops semperi L.S.R. Bergh, 1897 - syn of: Euselenops luniceps (G.L.C.F.D. Cuvier, 1816) - (PLEUROBRANCHAEIDAE)
- semperi, Pleurobranchus semperi (A.J.B.M. Vayssière, 1896) - (PLEUROBRANCHIDAE)
- semperi, Nembrotha semperi L.S.R. Bergh, 1907 - (POLYCERIDAE)
- semperi, Tympanotonos semperi G.P. Deshayes, 1864 † - (POTAMIDIDAE) (FOSSIL)
- semperi, Ringicula semperi Koch, 1862 † - (RINGICULIDAE) (FOSSIL)
- semperi, Galeodinopsis semperi (Wiechmann, 1871 †) - (RISSOIDAE) (FOSSIL)
- semperi, Opeas semperi (J.G. Hidalgo, 1888) - (SUBULINIDAE)
- semperi, Vitrinorbis semperi A. von Koenen, 1894 † - syn of: Orbitestella plicatella (A.E.M. Cossmann, 1888 †) - (TORNIDAE) (FOSSIL)
- semperi, Marionia semperi K.R. Jensen, 1994 - (TRITONIIDAE)
- semperi, Truncatella semperi W. Kobelt, 1884 - syn of: Truncatella guerinii A. Villa & J. Villa, 1841 - (TRUNCATELLIDAE)
- semperi, Lamellaria semperi L.S.R. Bergh - (VELUTINIDAE)
- semperi, Costacallista semperi (J.B.P.A. Lamarck, 1818) - (VENERIDAE)
- semperi boshuensis, Prosimnia semperi boshuensis C.N. Cate, 1973 - syn of: Prosimnia boshuensis C.N. Cate, 1973 - (OVULIDAE)
- semperi dautzenbergi, Calocochlia semperi dautzenbergi J.G. Hidalgo, 1901 - (BRADYBAENIDAE)
- semperi draconis, Prosimnia semperi draconis C.N. Cate, 1973 - syn of: Prosimnia draconis C.N. Cate, 1973 - (OVULIDAE)
- semperi turbinatus, Cirsochilus semperi turbinatus (G.P. Deshayes, 1863 †) - (COLLONIIDAE) (FOSSIL)
- Semperia, syn of: Genus Dyakia H.H. Godwin-Austen, 1891 (DYAKIIDAE)
- Semperia, syn of: Genus Emarginula J.B.P.A. Lamarck, 1801 (FISSURELLIDAE)
- semperiana, Cancellaria semperiana J.C.H. Crosse, 1863 - (CANCELLARIIDAE)
- semperiana, Cardiolucina semperiana (A. Issel, 1869) - (LUCINIDAE)
- semperiana, Lucina semperiana A. Issel, 1869 - syn of: Cardiolucina semperiana (A. Issel, 1869) - (LUCINIDAE)
- semperiana, Phacoides semperiana A. Issel, 1869 - syn of: Cardiolucina semperiana (A. Issel, 1869) - (LUCINIDAE)
- Semperoncis, Genus Semperoncis Y.I. Starobogatov, 1976 (ONCHIDIIDAE)
- semperornata, Platyclymenia richteri semperornata Petter, 1960 † - (PLATYCLYMENIIDAE) (FOSSIL)
- semperturbina, Serpentubina semperturbina Horný, 1964 † - (TUBINIDAE) (FOSSIL)
- Semperula, Genus Semperula G.J. Von Grimpe & H. Hoffmann, 1924 (VERONICELLIDAE)
- sempervivens, Anodonta sempervivens G.P. Deshayes, 1875 - syn of: Pilsbryoconcha exilis (I. Lea, 1839) - (UNIONIDAE)
- sempiternus, Bactrites sempiternus Shimanskiy, 1954 † - (BACTRITIDAE) (FOSSIL)
- semprinii, Formosana semprinii (P.V. Gredler, 1884) - (CLAUSILIIDAE)
- sempronii, Lauria sempronii J.G.F. de Charpentier, 1837 - syn of: Lauria cylindracea (E.M. Da Costa, 1778) - (LAURIIDAE)
- sempronii, Pupilla sempronii J.G.F. de Charpentier, 1837 - syn of: Lauria cylindracea (E.M. Da Costa, 1778) - (PUPILLIDAE)
- semseyi, Cenoceras semseyi Prinz, 1904 † - (CENOCERATIDAE) (FOSSIL)
- semseyi, Viviparus semseyi Halaváts, 1903 † - (VIVIPARIDAE) (FOSSIL)
- semseyiana, Galeodes semseyiana Erdös, 1973 † - syn of: Melongena lainei (B. de Basterot, 1825 †) - (MELONGENIDAE) (FOSSIL)
- semulikiensis, Dadagulella browni semulikiensis B. Rowson & P. Tattersfield, 2013 - (STREPTAXIDAE)
- Semuridia, Genus Semuridia Melville, 1956 (PTERIIDA (UNASSIGNED)) (FOSSIL)
aaa
abx
ack
acy
adn
aer
afs
ajd
alc
alj
alu
amc
ams
and
anh
anp
anu
apl
arb
ard
arh
ars
asr
atl
atu
aus
aut
bab
baj
bao
bas
baw
bem
bes
bid
bim
bit
bli
bom
bos
bov
bre
bri
bry
bum
bys
caa
cak
cam
cao
cas
cau
cem
ces
che
chk
chy
cio
cle
cob
coh
com
con
coo
cos
cot
cre
cri
cru
cud
cuo
cuy
cym
daa
dam
dav
ded
dem
deo
det
dib
dih
dir
dit
dom
dos
duc
duq
eag
ecr
egg
elf
elp
enh
eov
erf
erz
eud
eus
exb
exl
exy
faa
fan
fat
fes
fim
fle
flu
fos
fre
fuf
fur
fut
gaa
gam
gav
geo
gie
gis
gle
glu
goo
gre
gru
gug
guz
haa
ham
has
heb
hem
hes
hif
his
hom
hou
hun
hye
iac
ilm
imt
ind
inf
ing
int
inu
irm
isp
jaa
jao
jaw
joi
juk
kaa
kao
kaz
kes
kio
koc
kot
kuk
laa
lad
laf
lan
las
lau
lec
leo
leq
lew
lim
lio
liu
loo
lub
lun
luv
maa
mad
mah
mam
mao
mas
mav
mee
mem
mes
mey
mid
min
mio
mit
moe
moo
mos
mum
mut
nab
nao
nav
nel
neq
nex
nih
niu
noe
nou
nue
oaf
obn
obu
oci
oke
olk
oos
orc
oro
osu
ove
paa
paf
pam
paq
pas
pau
pay
pem
pes
pfi
phl
pid
pio
ple
plo
pom
pos
pre
pro
pru
psi
pul
pum
pup
put
pys
qag
qub
rab
rah
ras
red
reh
reu
rhu
rin
roc
rot
rox
rue
ruh
ryd
saa
sai
san
sao
sav
sce
sci
scy
sem
sen
ses
shl
sih
sin
sio
smo
som
soy
sph
spj
sra
stg
sts
suc
sum
suv
szo
tab
tal
taq
tay
ten
teo
tes
tha
thl
tif
toc
tos
tre
trl
try
tuc
tus
uac
ume
uni
urd
vaa
vap
vas
vep
ves
vid
vip
vis
vob
vup
waa
wam
weg
who
wom
xac
yaa
yot
zaa
zem
zoo
|