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Mollusca (133 239)
Subphylum Aculifera
Subphylum Conchifera
Subphylum Placophora accepted as Polyplacophora
Superclass Aplacophora
Class Amphineura accepted as Aculifera
Class Bivalvia (25 078)
Subclass Autobranchia (23 355)
Infraclass Heteroconchia (16 680)
Subterclass Archiheterodonta (1 210)
Subterclass Euheterodonta (11 395)
Subterclass Heterodonta
Subterclass Palaeoheterodonta (4 074)
Order Trigoniida (1 482)
Superfamily Megatrigonioidea van Hoepen, 1929 † (336)
Superfamily Myophorelloidea T. Kobayashi, 1954 † (376)
Superfamily Pseudocardinioidea Martinson, 1961 † (176)
Superfamily Trigonioidea Lamarck, 1819 (350)
Family Costatoriidae Newell & Boyd, 1975 † accepted as Myophoriidae Bronn, 1849 †
Family Eoastartidae Newell & Boyd, 1975 † accepted as Eoastartinae Newell & Boyd, 1975 †
Family Eoschizodidae Newell & Boyd, 1975 † (6)
Family Erugoniidae McRoberts, 2017 † (5)
Family Groeberellidae E. Pérez, Reyes & S. E. Damborenea, 1995 † (1)
Family Ladinomyidae Prinoth & Posenato, 2023 † (1)
Family Myophoriidae Bronn, 1849 † (71)
Family Prosogyrotrigoniidae T. Kobayashi, 1954 † (7)
Family Scaphellinidae Newell & Ciriacks, 1962 † (3)
Family Schizodidae Newell & Boyd, 1975 † (41)
Family Sinodoridae Pojeta & R.-J. Zhang, 1984 † accepted as Sinodorinae Pojeta & R.-J. Zhang, 1984 †
Family Trigoniidae Lamarck, 1819 (215)
Subfamily Austrotrigoniinae Skwarko, 1968 † (30)
Subfamily Minetrigoniinae T. Kobayashi, 1954 † (24)
Subfamily Neotrigoniinae T. Kobayashi, 1954 (22)
Subfamily Pleurotrigoniinae van Hoepen, 1929 † (19)
Subfamily Trigoniinae Lamarck, 1819 † (93)
Genus Cornbrashella Ayoub-Hannaa, M. R. Cooper, Abdelhady & Fürsich, 2024 † (2)
Genus Cotswoldella Ayoub-Hannaa, M. R. Cooper, Abdelhady & Fürsich, 2024 † (9)
Genus Lyridon J. De C. Sowerby, 1823 † accepted as Trigonia Bruguière, 1789 †
Genus Lyriodon Bronn, 1834 † accepted as Trigonia Bruguière, 1789 †
Genus Lyrodon Goldfuss, 1837 † accepted as Trigonia Bruguière, 1789 †
Genus Magharitrigonia Ayoub-Hannaa, M. R. Cooper, Abdelhady & Fürsich, 2024 † (4)
Genus Modestella Hautmann, 2001 † accepted as Modesticoncha Hautmann, 2009 †
Genus Modesticoncha Hautmann, 2009 † accepted as Primatrigonia Repin, 2001 †
Genus Neuquenitrigonia H. A. Leanza & Garate Zubillaga, 1987 † (2)
Genus Primatrigonia Repin, 2001 † (2)
Genus Protrigonia F.-X. Guo, 1985 † accepted as Primatrigonia Repin, 2001 †
Genus Trigonia Bruguière, 1789 † (74)
Subgenus Trigonia (Acanthotrigonia) van Hoepen, 1929 † accepted as Acanthotrigonia van Hoepen, 1929 †
Subgenus Trigonia (Awadia) A. M. Abdallah & Fahmi, 1969 † accepted as Parorthotrigonia Ayoub-Hannaa, M. R. Cooper, Abdelhady & Fürsich, 2024 †
Subgenus Trigonia (Clavitrigonia) A. F. Leanza, 1942 † accepted as Clavotrigonia Lebküchner, 1932 †
Subgenus Trigonia (Clavotrigonia) Lebküchner, 1932 † accepted as Myophorella Bayle, 1878 †
Subgenus Trigonia (Frenguelliella) A. F. Leanza, 1942 † accepted as Frenguelliella A. F. Leanza, 1942 †
Subgenus Trigonia (Galalea) Abdallah & Fahmi, 1969 † accepted as Trigonia (Awadia) A. M. Abdallah & Fahmi, 1969 †
Subgenus Trigonia (Heslingtonia) C. A. Fleming, 1987 † accepted as Heslingtonia C. A. Fleming, 1987 †
Subgenus Trigonia (Indotrigonia) Dietrich, 1933 † accepted as Indotrigonia Dietrich, 1933 †
Subgenus Trigonia (Iotrigonia) van Hoepen, 1929 † accepted as Iotrigonia van Hoepen, 1929 †
Subgenus Trigonia (Kumatrigonia) Tamura, 1959 † accepted as Kumatrigonia Tamura, 1959 †
Subgenus Trigonia (Laevitrigonia) Lebküchner, 1932 † accepted as Laevitrigonia Lebküchner, 1932 †
Subgenus Trigonia (Lyriodon) Bronn, 1834 † accepted as Trigonia Bruguière, 1789 †
Subgenus Trigonia (Megatrigonia) van Hoepen, 1929 † accepted as Megatrigonia van Hoepen, 1929 †
Subgenus Trigonia (Minetrigonia) T. Kobayashi & Katayama, 1938 † accepted as Minetrigonia T. Kobayashi & Katayama, 1938 †
Subgenus Trigonia (Myophorella) Bayle, 1878 † accepted as Myophorella Bayle, 1878 †
Species Trigonia (Myophorella) alina (Contejean, 1860) † accepted as Myophorella alina (Contejean, 1860) †
Variety Trigonia (Myophorella) alina var. haugi Chavan, 1952 †
Species Trigonia (Myophorella) bronni (Agassiz, 1840) † accepted as Myophorella bronni (Agassiz, 1840) †
Species Trigonia (Myophorella) mermodi Chavan, 1952 † accepted as Myophorella mermodi (Chavan, 1952) †
Species Trigonia (Myophorella) norberti Chavan, 1952 † accepted as Myophorella norberti (Chavan, 1952) †
Species Trigonia (Myophorella) perlata (Agassiz, 1840) † accepted as Myophorella perlata (Agassiz, 1840) †
Subgenus Trigonia (Neotrigonia) Cossmann, 1912 accepted as Neotrigonia Cossmann, 1912
Subgenus Trigonia (Primatrigonia) Repin, 2001 † accepted as Primatrigonia Repin, 2001 †
Subgenus Trigonia (Protrigonia) F.-X. Guo, 1985 † accepted as Primatrigonia Repin, 2001 †
Subgenus Trigonia (Quadratotrigonia) Dietrich, 1933 † accepted as Quadratotrigonia Dietrich, 1933 †
Subgenus Trigonia (Rutitrigonia) van Hoepen, 1929 † accepted as Rutitrigonia van Hoepen, 1929 †
Subgenus Trigonia (Scabrotrigonia) Dietrich, 1933 † accepted as Scabrotrigonia Dietrich, 1933 †
Subgenus Trigonia (Sphenotrigonia) Rennie, 1936 † accepted as Sphenotrigonia Rennie, 1936 †
Subgenus Trigonia (Steinmanella) Crickmay, 1930 † accepted as Steinmanella Crickmay, 1930 †
Subgenus Trigonia (Trigonia) Bruguière, 1789 † accepted as Trigonia Bruguière, 1789 †
Subgenus Trigonia (Vaugonia) Crickmay, 1930 † accepted as Vaugonia Crickmay, 1930 †
Species Trigonia abichi Anthula, 1899 † accepted as Tamaragonia abichi (Anthula, 1899) †
Species Trigonia abrupta Buch, 1839 † accepted as Buchotrigonia abrupta (Buch, 1839) †
Species Trigonia aclinisa Dykan, 1990 †
Species Trigonia acteon Munier-Chalmas, 1882 †
Species Trigonia aculeata A. d'Orbigny, 1850 † accepted as Orthotrigonia aculeata (A. d'Orbigny, 1850) †
Species Trigonia acuta Kitchin, 1903 †
Species Trigonia acuticostata McCoy, 1866 † accepted as Neotrigonia acuticostata (McCoy, 1866) †
Species Trigonia adeli Bigot, 1893 †
Species Trigonia aequicostata Gabb, 1869 †
Species Trigonia aequilatera R. A. Philippi, 1899 †
Species Trigonia affinis J. Sowerby, 1818 † accepted as Lycettitrigonia affinis (J. Sowerby, 1818) †
Species Trigonia agassizi Étallon, 1862 †
Species Trigonia agrioensis C. E. Weaver, 1931 † accepted as Tanzanitrigonia agrioensis (C. E. Weaver, 1931) †
Species Trigonia ainuana Yabe & Nagao, 1928 † accepted as Yeharella ainuana (Yabe & Nagao, 1928) †
Species Trigonia akuschaensis Anthula, 1899 † accepted as Eurotrigonia akuschaensis (Anthula, 1899) †
Species Trigonia alaeformis J. Sowerby, 1818 † accepted as Trigonia aliformis Parkinson, 1811 †
Species Trigonia albertaensis McLearn, 1919 †
Species Trigonia alberti R. A. Philippi, 1899 †
Species Trigonia alcobacensis Choffat, 1885 †
Species Trigonia alemanica Rollier, 1912 †
Species Trigonia aliformis Parkinson, 1811 † accepted as Eurotrigonia aliformis (Parkinson, 1811) †
Species Trigonia alina Contejean, 1860 † accepted as Myophorella alina (Contejean, 1860) †
Species Trigonia alsatica Rollier, 1912 †
Species Trigonia alta Conrad, 1852 †
Species Trigonia alta Kuljinskaja-Voronetz, 1936 †
Species Trigonia amarali R. A. Philippi, 1899 †
Species Trigonia americana Meek, 1873 †
Species Trigonia amudariensis Arkhanguelsky, 1916 † accepted as Amudariella amudariensis (Arkhanguelsky, 1916) †
Species Trigonia amuriensis Hector, 1886 † accepted as Haumurigonia pseudocaudata (Hector, 1886) †
Species Trigonia analoga Douvillé, 1916 † accepted as Valenciella analoga (Douvillé, 1916) †
Species Trigonia andrussovi Saveliev, 1960 †
Species Trigonia angulata J. De C. Sowerby, 1826 †
Species Trigonia angulicosta Gabb, 1877 † accepted as Eufalagonia angulicosta (Gabb, 1877) †
Species Trigonia angulifera Stoliczka, 1871 † accepted as Buchotrigonia angulifera (Stoliczka, 1871) †
Species Trigonia angusta R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia angustecostata Behrendsen, 1892 †
Species Trigonia angustula Bigot, 1893 †
Species Trigonia antarctica F. Péron & Lesueur, 1807 accepted as Neotrigonia margaritacea (Lamarck, 1804)
Species Trigonia antarctica Wilckens, 1910 † accepted as Orbigonina antarctica (Wilckens, 1910) †
Species Trigonia antiqua A. d'Orbigny, 1839 † accepted as Megalodon antiqua (A. d'Orbigny, 1839) †
Species Trigonia aralensis Arkhangelsky, 1912 † accepted as Romanovskiella aralensis (Arkhangelsky, 1912) †
Species Trigonia arata Lycett, 1863 †
Species Trigonia archiaciana A. d'Orbigny, 1844 † accepted as Oistotrigonia archiaciana (A. d'Orbigny, 1844) †
Species Trigonia arcuata Lamarck, 1819 †
Species Trigonia arcuata Ebray, 1858 †
Species Trigonia arduenna Buvignier, 1852 †
Species Trigonia arduennensis Rollier, 1912 †
Species Trigonia areafurcata Vetters, 1905 †
Species Trigonia areolata P. Marshall, 1919 † accepted as Kurinuia areolata (P. Marshall, 1919) †
Species Trigonia argentiniae Strand, 1928 †
Species Trigonia argentinica Jaworski, 1926 †
Species Trigonia arsinoe R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia ascheri Strand, 1928 †
Species Trigonia ascoldiensis Voronetz, 1933 †
Species Trigonia ashtonensis Arkell, 1930 †
Species Trigonia aspera Lamarck, 1819 †
Species Trigonia auressensis Coquand, 1862 †
Species Trigonia australiensis Strand, 1928 †
Species Trigonia autissiodorensis Munier-Chalmas, 1882 †
Species Trigonia aylesburiensis L. R. Cox, 1929 †
Species Trigonia azemmouri Gigout, 1951 †
Species Trigonia azzarolae Stoppani, 1863 †
Species Trigonia baccata Hagenow [sic] †
Species Trigonia baccifera R. A. Philippi, 1899 † accepted as Rinetrigonia baccifera (R. A. Philippi, 1899) †
Species Trigonia bachelieri A. d'Orbigny, 1850 †
Species Trigonia baillycensis de Loriol, 1893 †
Species Trigonia bajarunasi Saveliev, 1960 †
Species Trigonia baksanensis Mordvilko, 1960 †
Species Trigonia balmae C. A. Fleming, 1987 †
Species Trigonia baltica Stoll, 1934 † accepted as Trigonia loockiensis Strand, 1928 †
Species Trigonia barrensis Buvignier, 1852 †
Species Trigonia bartrami Stephenson, 1923 † accepted as Praescabrotrigonia bartrami (Stephenson, 1923) †
Species Trigonia bathonica Lycett, 1863 † accepted as Orthotrigonia bathonica (Lycett, 1863) †
Species Trigonia bathonicola Strand, 1928 †
Species Trigonia baylei R. A. Philippi, 1899 † accepted as Notoscabrotrigonia baylei (R. A. Philippi, 1899) †
Species Trigonia baylei Dollfus, 1862 † accepted as Orthotrigonia baylei (Dollfus, 1862) †
Species Trigonia beesleyana Lycett, 1874 † accepted as Psilotrigonia beesleyana (Lycett, 1874) †
Species Trigonia beirensis Choffat, 1885 †
Species Trigonia belgrandi Munier-Chalmas, 1882 †
Species Trigonia bella Lycett, 1877 †
Species Trigonia bergeroni Bigot, 1893 † accepted as Orthotrigonia bergeroni (Bigot, 1893) †
Species Trigonia beyrichi Krumbeck, 1906 † accepted as Lycettitrigonia beyrichi (Krumbeck, 1906) †
Species Trigonia beyschlagi G. Müller, 1900 † accepted as Indotrigonia beyschlagi (G. Müller, 1900) †
Species Trigonia bicostata A. d'Orbigny, 1850 †
Species Trigonia bielefeldensis Strand, 1928 †
Species Trigonia bifera Lycett, 1879 † accepted as Orthotrigonia bifera (Lycett, 1879) †
Species Trigonia bigoti Tornquist, 1898 †
Species Trigonia bigotia Strand, 1928 †
Species Trigonia bipartita A. d'Orbigny, 1850 †
Species Trigonia bipartita Bigot, 1893 † accepted as Trigonia bigotia Strand, 1928 †
Species Trigonia biseriata Étallon, 1862 †
Species Trigonia bizeti Bigot, 1893 †
Species Trigonia blakei Lycett, 1879 †
Species Trigonia blanckenhorni R. B. Newton, 1909 † accepted as Pleurotrigonia blanckenhorni (R. B. Newton, 1909) †
Species Trigonia boidini de Loriol, 1874 †
Species Trigonia boiti Lissón, 1930 † accepted as Allemanella boiti (Lissón, 1930) †
Species Trigonia boloniensis de Loriol, 1866 † accepted as Lycettitrigonia boloniensis (de Loriol, 1866) †
Species Trigonia bornhardti G. Müller, 1900 † accepted as Turikirella bornhardti (G. Müller, 1900) †
Species Trigonia bouchardi Oppel, 1857 †
Species Trigonia boussingaultii A. d'Orbigny, 1842 † accepted as Mediterraneotrigonia boussingaultii (A. d'Orbigny, 1842) †
Species Trigonia bowersiana F. M. Anderson, 1958 † accepted as Musagonia bowersiana (F. M. Anderson, 1958) †
Species Trigonia branconis Strand, 1928 †
Species Trigonia branneri F. M. Anderson, 1958 † accepted as Louella fitchi (E. L. Packard, 1921) †
Species Trigonia breoni Munier-Chalmas, 1882 †
Species Trigonia brevicostata Kitchin, 1903 † accepted as Magharitrigonia brevicostata (Kitchin, 1903) †
Species Trigonia brevicula Yehara, 1915 † accepted as Tamuragonia brevicula (Yehara, 1915) †
Species Trigonia brodiei Lycett, 1877 †
Species Trigonia bronnii Agassiz, 1840 † accepted as Myophorella bronnii (Agassiz, 1840) †
Species Trigonia brueggeni Strand, 1928 †
Species Trigonia buchsittensis de Loriol, 1881 †
Species Trigonia buckmani L. R. Cox, 1929 †
Species Trigonia burckhardti Jaworski, 1915 † accepted as Jaworskiella burckhardti (Jaworski, 1915) †
Species Trigonia burckhardtiola Strand, 1928 †
Species Trigonia bustamantina Feruglio, 1938 † accepted as Haumurigonia bustamantina (Feruglio, 1938) †
Species Trigonia calderoni R. A. Philippi, 1899 †
Species Trigonia californiana E. L. Packard, 1921 † accepted as Popenoella californiana (E. L. Packard, 1921) †
Species Trigonia campbellorum C. A. Fleming, 1987 † accepted as Heslingtonia campbellorum (C. A. Fleming, 1987) †
Species Trigonia cancellata T. Wright, 1860 †
Species Trigonia cardiniiformis Kitchin, 1903 † accepted as Kellygonia cardiniiformis (Kitchin, 1903) †
Species Trigonia cardissa Agassiz, 1840 †
Species Trigonia cardissoides Lamarck, 1819 † accepted as Opis cardissoides (Lamarck, 1819) †
Species Trigonia cardissoides Zieten, 1833 † accepted as Neoschizodus cardissoides (Zieten, 1833) †
Species Trigonia carinata Agassiz, 1840 †
Species Trigonia carrei Munier-Chalmas, 1865 †
Species Trigonia carrincurensis A. F. Leanza, 1941 † accepted as Anditrigonia carrincurensis (A. F. Leanza, 1941) †
Species Trigonia cartieri de Loriol, 1881 †
Species Trigonia cassiope A. d'Orbigny, 1850 †
Species Trigonia castor A. d'Orbigny, 1850 †
Species Trigonia castrovillensis Stephenson, 1941 † accepted as Tennessiella castrovillensis (Stephenson, 1941) †
Species Trigonia catanlilensis C. E. Weaver, 1931 † accepted as Jaworskiella burckhardti (Jaworski, 1915) †
Species Trigonia catenifera Hupé, 1854 †
Species Trigonia catenulata [sic] † accepted as Trigonia crenulata Lamarck, 1819 †
Species Trigonia caucasica Bayern, 1876 † accepted as Litschkovitrigonia caucasica (Bayern, 1876) †
Species Trigonia caudata Agassiz, 1840 † accepted as Eurotrigonia caudata (Agassiz, 1840) †
Species Trigonia cazadoriana Wilckens, 1907 † accepted as Acanthotrigonia cazadoriana (Wilckens, 1907) †
Species Trigonia cerulia Whitfield, 1885 † accepted as Kauffmanella cerulia (Whitfield, 1885) †
Species Trigonia chacaicoensis Lambert, 1944 † accepted as Eoanditrigonia chacaicoensis (Lambert, 1944) †
Species Trigonia chanka Kuljinskaja-Voronetz, 1936 †
Species Trigonia chariensis Kitchin, 1903 † accepted as Trigonia elongata J. De C. Sowerby, 1823 †
Species Trigonia charlockensis Kellaway & V. Wilson, 1941 †
Species Trigonia charlottensis E. L. Packard, 1921 †
Species Trigonia charltonensis Douglas & Arkell, 1928 †
Species Trigonia chatillonensis de Loriol, 1904 †
Species Trigonia cherahilensis Mongin, 1951 † accepted as Lutetigonia cherahilensis (Mongin, 1951) †
Species Trigonia chilicola Strand, 1928 †
Species Trigonia chiron A. d'Orbigny, 1850 †
Species Trigonia chivensis Arkhanguelsky, 1916 † accepted as Incomatiella chivensis (Arkhanguelsky, 1916) †
Species Trigonia choffatensis Strand, 1928 †
Species Trigonia choffati Bigot, 1893 †
Species Trigonia chubutensis Feruglio, 1934 † accepted as Frenguelliella chubutensis (Feruglio, 1934) †
Species Trigonia chunumayensis Jaworski, 1915 †
Species Trigonia churchi F. M. Anderson, 1958 † accepted as Notoscabrotrigonia evansana (Meek, 1858) †
Species Trigonia cincta Agassiz, 1840 † accepted as Quadratotrigonia cincta (Agassiz, 1840) †
Species Trigonia cinctuta Etheridge, 1902 † accepted as Nototrigonia cinctuta (Etheridge, 1902) †
Species Trigonia ciplyana Briart, 1888 †
Species Trigonia clapensis Terquem & Jourdy, 1869 †
Species Trigonia clathrata Agassiz, 1840 † accepted as Myophorella clathrata (Agassiz, 1840) †
Species Trigonia clathratula Strand, 1928 †
Species Trigonia clavata [sic] † accepted as Trigonia clavellata Parkinson, 1811 †
Species Trigonia clavellata Parkinson, 1811 † accepted as Myophorella clavellata (Parkinson, 1811) †
Species Trigonia clavellata R. A. Philippi, 1899 †
Species Trigonia clavellulata Strand, 1928 † accepted as Myophorella clavellulata (Strand, 1828) †
Species Trigonia clavigera Cragin, 1893 † accepted as Praescabrotrigonia clavigera (Cragin, 1893) †
Species Trigonia clavocostata Lycett, 1850 †
Species Trigonia clavulosa Rigaux & Sauvage, 1868 † accepted as Orthotrigonia clavulosa (Rigaux & Sauvage, 1868) †
Species Trigonia clio A. d'Orbigny, 1850 †
Species Trigonia clivosa Credner, 1863 † accepted as Myophorella clivosa (Credner, 1863) †
Species Trigonia clytia A. d'Orbigny, 1850 †
Species Trigonia coihuicoensis C. E. Weaver, 1931 † accepted as Leanzatrigonia coihuicoensis (C. E. Weaver, 1931) †
Species Trigonia collombi Vilanova y Piera, 1863 † accepted as Syrotrigonia collombi (Vilanova y Piera, 1863) †
Species Trigonia columbiana E. L. Packard, 1921 † accepted as Columbitrigonia columbiana (E. L. Packard, 1921) †
Species Trigonia colusaensis F. M. Anderson, 1958 † accepted as Yaadia leana (Gabb, 1877) †
Species Trigonia comberjonensis Strand, 1928 † accepted as Orthotrigonia comberjonensis (Strand, 1928) †
Species Trigonia complanata Lycett, 1872 †
Species Trigonia composita Lycett, 1860 †
Species Trigonia compta Lycett, 1863 †
Species Trigonia concentrica Agassiz, 1840 †
Species Trigonia concentrica Cragin, 1893 †
Species Trigonia concinna F. A. Roemer, 1839 †
Species Trigonia condoni E. L. Packard, 1921 † accepted as Columbitrigonia condoni (E. L. Packard, 1921) †
Species Trigonia conferticostata Cragin, 1905 †
Species Trigonia conformis Agassiz, 1840 †
Species Trigonia conjungens J. Phillips, 1829 †
Species Trigonia conradi Meek & Hayden, 1860 †
Species Trigonia consanguinea R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia consobrina Eichwald, 1871 †
Species Trigonia constantii A. d'Orbigny, 1844 † accepted as Macheromenilia constantii (A. d'Orbigny, 1844) †
Species Trigonia contejeani Thurmann, 1863 †
Species Trigonia copiapina R. A. Philippi, 1899 †
Species Trigonia coquandi R. A. Philippi, 1899 †
Species Trigonia coquandi Lissón, 1930 † accepted as Buchotrigonia angulifera (Stoliczka, 1871) †
Species Trigonia coquandiana A. d'Orbigny, 1844 † accepted as Lycettitrigonia coquandiana (A. d'Orbigny, 1844) †
Species Trigonia coqueiroensis Maury, 1937 †
Species Trigonia coralliensis Strand, 1928 †
Species Trigonia corallina A. d'Orbigny, 1850 †
Species Trigonia corbierensis Petter-Receveur, 1955 †
Species Trigonia cordata C. Drouët, 1825 †
Species Trigonia corderoi Lambert, 1944 †
Species Trigonia cornbrashensis Strand, 1928 †
Species Trigonia cornuta R. A. Philippi, 1899 †
Species Trigonia costata Parkinson, 1811 †
Species Trigonia costatula Lycett, 1850 †
Species Trigonia costatula Quenstedt, 1857 † accepted as Trigonia coralliensis Strand, 1928 †
Species Trigonia costellata Agassiz, 1840 †
Species Trigonia costigera Lycett, 1879 † accepted as Apiotrigonia costigera (Lycett, 1979) †
Species Trigonia cottae Bruder, 1885 †
Species Trigonia cottaldi de Loriol, 1868 †
Species Trigonia couzonensis Riche, 1904 †
Species Trigonia covuncoensis Lambert, 1944 † accepted as Levytrigonia covuncoensis (Lambert, 1944) †
Species Trigonia cragini Stoyanow, 1949 † accepted as Sonoragonia cragini (Stoyanow, 1949) †
Species Trigonia crassa Kitchin, 1903 † accepted as Indotrigonia beyschlagi (G. Müller, 1900) †
Species Trigonia crassatellina Lamarck, 1819 †
Species Trigonia crassidens R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia crebraecostata Pugaczewska, 1976 †
Species Trigonia crenifera Stoliczka, 1871 † accepted as Oistotrigonia crenifera (Stoliczka, 1871) †
Species Trigonia crenulata Lamarck, 1819 † accepted as Praescabrotrigonia crenulata (Lamarck, 1819) †
Species Trigonia crenulifera Lycett, 1877 † accepted as Praescabrotrigonia crenulifera (Lycett, 1877) †
Species Trigonia cricki R. B. Newton, 1909 † accepted as Ptilotrigonia cricki (R. B. Newton, 1909) †
Species Trigonia cristagalli Bigot, 1893 † accepted as Magharitrigonia cristagalli (Bigot, 1893) †
Species Trigonia culleni Lycett, 1877 † accepted as Cotswoldella culleni (Lycett, 1877) †
Species Trigonia cuneata [sic] † accepted as Trigonia cuneiformis Conrad, 1852 †
Species Trigonia cuneata Sowerby [sic] †
Species Trigonia cuneiformis Conrad, 1852 † accepted as Eurotrigonia cuneiformis (Conrad, 1852) †
Species Trigonia cunningtoni Lycett, 1875 † accepted as Oistotrigonia cunningtoni (Lycett, 1875) †
Species Trigonia curmontensis de Loriol, 1872 †
Species Trigonia curta Mordvilko, 1956 †
Species Trigonia cuspidata J. De C. Sowerby, 1826 †
Species Trigonia cybele A. d'Orbigny, 1850 †
Species Trigonia cycloides R. A. Philippi, 1899 †
Species Trigonia cymba Contejean, 1860 †
Species Trigonia daedalea Parkinson, 1811 † accepted as Neoquadratotrigonia daedalea (Parkinson, 1811) †
Species Trigonia damoniana de Loriol, 1866 †
Species Trigonia damoniella Strand, 1928 †
Species Trigonia daphne de Loriol, 1893 †
Species Trigonia darwaseana Romanovsky, 1890 † accepted as Bogdanovaella darwaseana (Romanovsky, 1890) †
Species Trigonia datemasamunei Yehara, 1915 † accepted as Metacanthotrigonia datemasamunei (Yehara, 1915) †
Species Trigonia dawsoni Whiteaves, 1878 † accepted as Haidaia dawsoni (Whiteaves, 1878) †
Species Trigonia debilis Lycett, 1877 † accepted as Lycettitrigonia debilis (Lycett, 1877) †
Species Trigonia debuchii Geinitz, 1840 † accepted as Bohemigonia debuchii (Geinitz, 1840) †
Species Trigonia decipiens Munier-Chalmas, 1882 †
Species Trigonia decipiens R. A. Philippi, 1899 †
Species Trigonia deckeina Kubota, 1952 † accepted as Yeharella deckeina (Kubota, 1952) †
Species Trigonia decora Stoliczka, 1871 † accepted as Mediterraneotrigonia decora (Stoliczka, 1871) †
Species Trigonia decorata Lycett, 1853 †
Species Trigonia deeckeella Strand, 1928 †
Species Trigonia deeckei Strand, 1928 †
Species Trigonia delafossei Bayle & Coquand, 1851 † accepted as Rinetrigonia delafossei (Bayle & Coquand, 1851) †
Species Trigonia delorenzoi Greco, 1899 †
Species Trigonia densestriata Behrendsen, 1892 † accepted as Cotswoldella densestriata (Behrendsen, 1892) †
Species Trigonia densicostata P. Marshall, 1919 † accepted as Verticordia densicostata (P. Marshall, 1919) †
Species Trigonia densicostata Roeder, 1882 †
Species Trigonia densinoda Etheridge, 1881 † accepted as Pseudomyophorella densinoda (Etheridge, 1881) †
Species Trigonia denticulata Agassiz, 1840 †
Species Trigonia depauperata Douvillé, 1916 † accepted as Valenciella depauperata (Douvillé, 1916) †
Species Trigonia depereti Riche, 1904 † accepted as Myophorella depereti (Riche, 1904) †
Species Trigonia deschutensis E. L. Packard, 1921 † accepted as Notoscabrotrigonia oregana (E. L. Packard, 1921) †
Species Trigonia deshayesi Vilanova y Piera, 1863 † accepted as Syrotrigonia deshayesi (Vilanova y Piera, 1863) †
Species Trigonia deslongchampsii Munier-Chalmas, 1865 † accepted as Neoquadratotrigonia deslongchampsii (Munier-Chalmas, 1865) †
Species Trigonia destefanii Feruglio, 1937 †
Species Trigonia detrita Terquem & Jourdy, 1869 †
Species Trigonia devexa Eichwald, 1871 †
Species Trigonia dhosaensis Kitchin, 1903 † accepted as Kitchingonia dhosaensis (Kitchin, 1903) †
Species Trigonia dietrichi E. Lange, 1914 † accepted as Erichlangeia dietrichi (E. Lange, 1914) †
Species Trigonia dilapsa Yehara, 1923 † accepted as Tamuragonia dilapsa (Yehara, 1923) †
Species Trigonia discors R. A. Philippi, 1899 † accepted as Damborenella discors (R. A. Philippi, 1899) †
Species Trigonia disparilis A. d'Orbigny, 1844 † accepted as Dorbigonia disparilis (A. d'Orbigny, 1844) †
Species Trigonia distans Coquand, 1862 † accepted as Lyriodon ethra Coquand, 1880 †
Species Trigonia distans Conrad, 1852 † accepted as Syrotrigonia distans (Conrad, 1852) †
Species Trigonia distincta Kitchin, 1903 † accepted as Cornbrashella distincta (Kitchin, 1903) †
Species Trigonia divaricata A. d'Orbigny, 1844 †
Species Trigonia diversicostata Whiteaves, 1876 † accepted as Heterotrigonia diversicostata (Whiteaves, 1876) †
Species Trigonia domeykoana R. A. Philippi, 1860 †
Species Trigonia doroschini Eichwald, 1871 †
Species Trigonia dorsetensis L. R. Cox, 1929 †
Species Trigonia douvillei Lissón, 1930 † accepted as Mediterraneotrigonia douvillei (Lissón, 1930) †
Species Trigonia douvillei El Din, 1955 † accepted as Praescabrotrigonia douvillei (El Din, 1955) †
Species Trigonia dubia Kitchin, 1903 † accepted as Mayesella dubia (Kitchin, 1903) †
Species Trigonia dubia G. B. Sowerby II, 1884
Species Trigonia dubia O. Boettger, 1880 †
Species Trigonia dumblei Stoyanow, 1949 † accepted as Cochisella dumblei (Stoyanow, 1949) †
Species Trigonia dumortieri Munier-Chalmas, 1882 †
Species Trigonia dumortieri Rollier, 1912 †
Species Trigonia dunkeri Hagenow [sic] †
Species Trigonia dunscombensis Lycett, 1877 † accepted as Lycettitrigonia dunscombensis (Lycett, 1877) †
Species Trigonia duplicata J. Sowerby, 1819 † accepted as Orthotrigonia duplicata (J. Sowerby, 1819) †
Species Trigonia eccentrica Parkinson, 1811 † accepted as Lycettitrigonia eccentrica (Parkinson, 1811) †
Species Trigonia echinata A. d'Orbigny, 1850 †
Species Trigonia echinophila J. B. Greppin, 1870 †
Species Trigonia echinulata Coquand, 1859 †
Species Trigonia ecplecta Wilckens, 1907 †
Species Trigonia edmundi de Loriol, 1874 †
Species Trigonia ehningensis Rollier, 1912 †
Species Trigonia elegans W. H. Baily, 1855 † accepted as Linotrigonia elegans (W. H. Baily, 1855) †
Species Trigonia elegantissima Meek, 1873 † accepted as Cotswoldella elegantissima (Meek, 1873) †
Species Trigonia elisae Briart & Cornet, 1868 † accepted as Mangyschlakella elisae (Briart & Cornet, 1868) †
Species Trigonia elongata J. De C. Sowerby, 1823 †
Species Trigonia emoryi Conrad, 1857 † accepted as Praescabrotrigonia emoryi (Conrad, 1857) †
Species Trigonia emoryioides Trechmann, 1927 † accepted as Praescabrotrigonia emoryioides (Trechmann, 1927) †
Species Trigonia engeli Benecke, 1905 †
Species Trigonia eptingensis H. Schwarz, 1973 †
Species Trigonia erbeni Alencáster de Cserna, 1963 †
Species Trigonia erycina R. A. Philippi, 1899 † accepted as Philippiella erycina (R. A. Philippi, 1899) †
Species Trigonia etalloni de Loriol, 1872 †
Species Trigonia etheridgei Lycett, 1875 † accepted as Notoscabrotrigonia etheridgei (Lycett, 1875) †
Species Trigonia eudesi Bigot, 1893 †
Species Trigonia eudora R. A. Philippi, 1899 †
Species Trigonia eufalensis Gabb, 1860 † accepted as Gabbigonia eufalensis (Gabb, 1860) †
Species Trigonia eufaulensis [sic] † accepted as Trigonia eufalensis Gabb, 1860 †
Species Trigonia eugenii Bigot, 1893 †
Species Trigonia evansana Meek, 1858 † accepted as Notoscabrotrigonia evansana (Meek, 1858) †
Species Trigonia exaltata Lycett, 1877 † accepted as Myophorella exaltata (Lycett, 1877) †
Species Trigonia exigua Lycett, 1853 †
Species Trigonia eximia R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia exortiva Kitchin, 1903 † accepted as Charigonia exortiva (Kitchin, 1903) †
Species Trigonia exotica Möricke, 1894 † accepted as Promyophorella exotica (Möricke, 1894) †
Species Trigonia extentum Repman, 1963 †
Species Trigonia falciformis R. A. Philippi, 1899 †
Species Trigonia falcki Rouillier & Vosinsky, 1849 † accepted as Mayesella falcki (Rouillier & Vosinsky, 1849) †
Species Trigonia fallax R. A. Philippi, 1899 †
Species Trigonia ferdinandi Frech, 1916 †
Species Trigonia ferganensis Arkhanguelsky, 1916 † accepted as Bogdanovaella ferganensis (Arkhanguelsky, 1916) †
Species Trigonia ferrieri McLearn, 1924 †
Species Trigonia ferryi Munier-Chalmas, 1865 †
Species Trigonia feruglioi Piatnitzky, 1938 † accepted as Pisotrigonia feruglioi (Piatnitzky, 1938) †
Species Trigonia feuguerollensis Bigot, 1893 †
Species Trigonia fimbriata Lycett, 1877 †
Species Trigonia fischeri Munier-Chalmas, 1882 †
Species Trigonia fischeri Bigot, 1893 † accepted as Trigonia trouvillensis Strand, 1928 †
Species Trigonia fitchi E. L. Packard, 1921 † accepted as Louella fitchi (E. L. Packard, 1921) †
Species Trigonia fittonella Strand, 1928 †
Species Trigonia fittoni Leymerie, 1842 † accepted as Noelmorrisia fittoni (Leymerie, 1842) †
Species Trigonia flecta J. Morris & Lycett, 1853 †
Species Trigonia flexicostata Burwash, 1914 † accepted as Apiotrigonia flexicostata (Burwash, 1914) †
Species Trigonia flexicostata Fritzsche, 1924 † accepted as Incagonia flexicostata (Fritzsche, 1924) †
Species Trigonia flexuosa Lamarck, 1819 †
Species Trigonia fluehmanni R. A. Philippi, 1899 †
Species Trigonia foncki R. A. Philippi, 1899 †
Species Trigonia forbesii Lycett, 1875 † accepted as Linotrigonia forbesii (Lycett, 1875) †
Species Trigonia formosa Lycett, 1860 † accepted as Clavotrigonia formosa (Lycett, 1860) †
Species Trigonia forti Lissón, 1930 † accepted as Incagonia forti (Lissón, 1930) †
Species Trigonia fortinensis Lambert, 1944 †
Species Trigonia foveata R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia freixialensis Choffat, 1885 † accepted as Lusitanigonia freixialensis (Choffat, 1885) †
Species Trigonia frenguellii Mariñelarena, 1959 † accepted as Antutrigonia frenguellii (Mariñelarena, 1959) †
Species Trigonia gabbensis Strand, 1928 †
Species Trigonia gadoisi Cossmann, 1911 † accepted as Cotswoldella gadoisi (Cossmann, 1911) †
Species Trigonia gallica Rollier, 1912 †
Species Trigonia gampsorrhyncha R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia gemmata Lycett, 1853 † accepted as Orthotrigonia gemmata (Lycett, 1853) †
Species Trigonia geographica Agassiz, 1840 †
Species Trigonia gerassimovi Mordvilko, 1937 †
Species Trigonia germanica J. Roemer, 1911 †
Species Trigonia gerthi Lissón, 1930 † accepted as Incagonia gerthi (Lissón, 1930) †
Species Trigonia gertrudae Mordvilko †
Species Trigonia geulemensis F. Vogel, 1895 † accepted as Oistotrigonia geulemensis (F. Vogel, 1895) †
Species Trigonia gibboniana I. Lea, 1840 † accepted as Mediterraneotrigonia gibboniana (I. Lea, 1840) †
Species Trigonia gibbosa J. Sowerby, 1819 †
Species Trigonia gilleti Basse, 1932 † accepted as Elianegonia gilleti (Basse, 1932) †
Species Trigonia gillieroni J. B. Greppin, 1870 †
Species Trigonia girardoti de Loriol, 1904 †
Species Trigonia glabra R. A. Philippi, 1887 †
Species Trigonia glabrata R. A. Philippi, 1899 †
Species Trigonia glaciana Sturm, 1901 † accepted as Scabrotrigonia glaciana (Sturm, 1901) †
Species Trigonia gladkowskii Shheglova-Borodina, 1960 † accepted as Kushmurunskya gladkowskii (Shheglova-Borodina, 1960) †
Species Trigonia glaphyra R. A. Philippi, 1899 † accepted as Rinetrigonia glaphyra (R. A. Philippi, 1899) †
Species Trigonia glasvillei Munier-Chalmas, 1865 †
Species Trigonia glosensis Bigot, 1893 †
Species Trigonia glyptica H. Woods, 1917 † accepted as Iotrigonia glyptica (H. Woods, 1917) †
Species Trigonia goldfusii Zieten, 1833 † accepted as Costatoria goldfussii (Zieten, 1833) †
Species Trigonia goldfussii Agassiz, 1840 †
Species Trigonia goodellii Cragin, 1897 † accepted as Craginella goodellii (Cragin, 1897) †
Species Trigonia gordoni M. Whitney, 1952 † accepted as Cochisella gordoni (M. Whitney, 1952) †
Species Trigonia gottschei Möricke, 1894 †
Species Trigonia gracilicosta Étallon, 1862 †
Species Trigonia gracilis Kitchin, 1903 † accepted as Charigonia gracilis (Kitchin, 1903) †
Species Trigonia granigera Contejean, 1860 †
Species Trigonia grayensis Étallon, 1864 †
Species Trigonia greppini Étallon, 1863 †
Species Trigonia gresslyi Thurmann, 1863 †
Species Trigonia griesbachi Lycett, 1872 † accepted as Orthotrigonia griesbachi (Lycett, 1872) †
Species Trigonia groeberi C. E. Weaver, 1931 † accepted as Antutrigonia groeberi (C. E. Weaver, 1931) †
Species Trigonia gryphitica Möricke, 1894 † accepted as Moerickella infraclavellata (Möricke, 1894) †
Species Trigonia guadalupae Böse, 1910 † accepted as Notoscabrotrigonia guadalupae (Böse, 1910) †
Species Trigonia guhsani McLearn, 1926 †
Species Trigonia guildi Stoyanow, 1949 † accepted as Cochisella guildi (Stoyanow, 1949) †
Species Trigonia guisei Lycett, 1883 †
Species Trigonia halimede R. A. Philippi, 1899 †
Species Trigonia hanetiana A. d'Orbigny, 1841 † accepted as Pacitrigonia hanetiana (A. d'Orbigny, 1841) †
Species Trigonia harpa Leymerie, 1842 † accepted as Trigonia carinata Agassiz, 1840 †
Species Trigonia hauchecornei M. Schmidt, 1905 † accepted as Tamaragonia hauchecornei (M. Schmidt, 1905) †
Species Trigonia haupti Lambert, 1944 † accepted as Philippiella haupti (Lambert, 1944) †
Species Trigonia hauterivica Strand, 1928 † accepted as Trigonia carinata Agassiz, 1840 †
Species Trigonia haynensis Stephenson, 1923 † accepted as Kauffmanella haynensis (Stephenson, 1923) †
Species Trigonia heberti Munier-Chalmas, 1865 † accepted as Turbitrigonia incurva (Benett, 1831) †
Species Trigonia hegiensis Saeki, 1925 † accepted as Minetrigonia hegiensis (Saeki, 1925) †
Species Trigonia helena de Loriol, 1893 †
Species Trigonia hemisphaerica Lycett, 1853 † accepted as Cotswoldella hemisphaerica (Lycett, 1853) †
Species Trigonia hemphilli F. M. Anderson, 1958 † accepted as Popenoella hemphilli (F. M. Anderson, 1958) †
Species Trigonia hennigi E. Lange, 1914 † accepted as Pseudoyaadia hennigi (E. Lange, 1914) †
Species Trigonia hennigiana Strand, 1928 †
Species Trigonia heterosculpta Stanton, 1901 † accepted as Mayesella heterosculpta (Stanton, 1901) †
Species Trigonia heva Dollfus, 1863 †
Species Trigonia higazyi Abbass, 1962 † accepted as Valenciella higazyi (Abbass, 1962) †
Species Trigonia hilli Strand, 1928 †
Species Trigonia hispida Kitchin, 1903 † accepted as Charigonia hispida (Kitchin, 1903) †
Species Trigonia hokkaidoana Yehara, 1915 † accepted as Notoscabrotrigonia hokkaidoana (Yehara, 1915) †
Species Trigonia holubi Kitchin, 1908 † accepted as Steinmanella holubi (Kitchin, 1908) †
Species Trigonia hondaana I. Lea, 1840 † accepted as Mediterraneotrigonia hondaana (I. Lea, 1840) †
Species Trigonia hopkinsi Olsson, 1944 † accepted as Neobuchotrigonia hopkinsi (Olsson, 1944) †
Species Trigonia hosourensis Yokoyama, 1904 † accepted as Geratrigonia hosourensis (Yokoyama, 1904) †
Species Trigonia howitti McCoy, 1875 † accepted as Neotrigonia howitti (McCoy, 1875) †
Species Trigonia hudlestoni Lycett, 1877 †
Species Trigonia huenickeni H. A. Leanza & Garate Zubillaga, 1985 † accepted as Neuquenitrigonia huenickeni (H. A. Leanza & Garate Zubillaga, 1985) †
Species Trigonia humboldtii Buch, 1839 † accepted as Villamilia humboldtii (Buch, 1839) †
Species Trigonia humilis R. A. Philippi, 1899 †
Species Trigonia hunstantonensis Seeley, 1861 †
Species Trigonia hybrida F. A. Roemer, 1836 †
Species Trigonia hyriiformis Wilckens, 1910 † accepted as Goniomya hyriiformis (Wilckens, 1910) †
Species Trigonia imbricata J. De C. Sowerby, 1826 † accepted as Retetrigonia imbricata (J. de C. Sowerby, 1826) †
Species Trigonia impressa J. Sowerby, 1828 †
Species Trigonia inca Fritzsche, 1924 † accepted as Incagonia inca (Fritzsche, 1924) †
Species Trigonia incerta Portlock, 1843 †
Species Trigonia inconspicua R. A. Philippi, 1899 †
Species Trigonia incurva Benett, 1831 † accepted as Turbitrigonia incurva (Benett, 1831) †
Species Trigonia indica Stoliczka, 1871 † accepted as Jaitlygonia indica (Stoliczka, 1871) †
Species Trigonia inexspectata Jaworski, 1915 † accepted as Frenguelliella inexspectata (Jaworski, 1815) †
Species Trigonia inezana E. L. Packard, 1921 † accepted as Notoscabrotrigonia evansana (Meek, 1858) †
Species Trigonia inflata Lamarck, 1819 †
Species Trigonia inflata F. A. Roemer, 1839 †
Species Trigonia infraclavellata Möricke, 1894 † accepted as Moerickella infraclavellata (Möricke, 1894) †
Species Trigonia infracostata Lycett, 1881 †
Species Trigonia ingens Lycett, 1872 † accepted as Myophorella intermedia (Fahrenkohl, 1844) †
Species Trigonia inguschensis Renngarten, 1926 † accepted as Saveligonia inguschensis (Renngarten, 1926) †
Species Trigonia inornata A. d'Orbigny, 1844 †
Species Trigonia inostranzevi Strémooukhov, 1897 †
Species Trigonia inouyei Yehara, 1921 †
Species Trigonia interlaevigata Quenstedt, 1857 †
Species Trigonia intersitans Tate, 1896 † accepted as Eotrigonia intersitans (Tate, 1896) †
Species Trigonia irregularis Seebach, 1864 †
Species Trigonia ivantischini Kuljinskaja-Voronetz, 1936 † accepted as Orthotrigonia ivantischini (Kuljinskaja-Voronetz, 1936) †
Species Trigonia jablanica Strand, 1928 †
Species Trigonia jacksonensis E. L. Packard, 1921 † accepted as Earlpackardia jacksonensis (E. L. Packard, 1921) †
Species Trigonia jacobi Dechaseaux, 1932 †
Species Trigonia jakshysaurensis Luppov, 1932 † accepted as Mayesella jakshysaurensis (Luppov, 1932) †
Species Trigonia janenschi E. Lange, 1914 † accepted as Turikirella janenschi (E. Lange, 1914) †
Species Trigonia japonica Yehara, 1923 † accepted as Yeharella japonica (Yehara, 1923) †
Species Trigonia jarryi Bigot, 1893 †
Species Trigonia jimbonis Strand, 1928 † accepted as Himenourella jimbonis (Strand, 1928) †
Species Trigonia joassi Lycett, 1874 †
Species Trigonia jonioi Rouillier & Vosinsky, 1849 † accepted as Myophorella intermedia (Fahrenkohl, 1844) †
Species Trigonia juddiana Lycett, 1872 †
Species Trigonia jukesii A. Adams, 1850 accepted as Neotrigonia uniophora (J. E. Gray, 1847)
Species Trigonia julii Étallon, 1863 †
Species Trigonia jumarensis Kitchin, 1903 † accepted as Charigonia jumarensis (Kitchin, 1903) †
Species Trigonia kabardinensis Mordvilko, 1937 †
Species Trigonia kawhiana Trechmann, 1923 † accepted as Vaugonia kawhiana (Trechmann, 1923) †
Species Trigonia kayana F. M. Anderson, 1938 †
Species Trigonia keepingi Lycett, 1877 † accepted as Myophorella keepingi (Lycett, 1877) †
Species Trigonia kenti L. R. Cox, 1965 †
Species Trigonia kerfornei Bigot, 1893 †
Species Trigonia kheraensis L. R. Cox, 1952 †
Species Trigonia kidugalloensis L. R. Cox, 1965 † accepted as Cotswoldella kidugalloensis (L. R. Cox, 1965) †
Species Trigonia kikuchiana Yokoyama, 1891 † accepted as Nipponitrigonia kikuchiana (Yokoyama, 1891) †
Species Trigonia kimurai Tokunaga & Shimizu, 1926 † accepted as Yeharella kimurai (Tokunaga & Shimizu, 1926) †
Species Trigonia kiprianovi Strémooukhov, 1897 †
Species Trigonia kitchini Stoyanow, 1949 † accepted as Sonoragonia scotti M. R. Cooper, 2021 †
Species Trigonia kitchini Strand, 1928 †
Species Trigonia kitchini E. H. L. Schwarz, 1915 † accepted as Notoscabrotrigonia kitchini (E. H. L. Schwarz, 1915) †
Species Trigonia klamathonia F. M. Anderson, 1958 † accepted as Notoscabrotrigonia klamathonia (F. M. Anderson, 1958) †
Species Trigonia knighti Pringle, 1960 † accepted as Notoscabrotrigonia knighti (Pringle, 1960) †
Species Trigonia kobyi Choffat, 1885 † accepted as Lusitanigonia kobyi (Choffat, 1885) †
Species Trigonia kotoi Yehara, 1915 † accepted as Notoscabrotrigonia kotoi (Yehara, 1915) †
Species Trigonia kraussi Kitchin, 1908 † accepted as Pisotrigonia kraussi (Kitchin, 1908) †
Species Trigonia krenkeli E. Lange, 1914 † accepted as Zulutrigonia krenkeli (E. Lange, 1914) †
Species Trigonia krugi R. A. Philippi, 1899 †
Species Trigonia kuehni G. Müller, 1900 † accepted as Mayesella kuehni (G. Müller, 1900) †
Species Trigonia kuemmeli Weller, 1907 † accepted as Gabbigonia kuemmeli (Weller, 1907) †
Species Trigonia kurri Oppel, 1857 † accepted as Myophorella kurri (Oppel, 1857) †
Species Trigonia kutchensis Kitchin, 1903 † accepted as Charigonia kutchensis (Kitchin, 1903) †
Species Trigonia laevicostata Redlich, 1894 †
Species Trigonia laevigata Zieten, 1833 † accepted as Neoschizodus laevigatus (Zieten, 1833) †
Species Trigonia laeviuscula Lycett, 1875 † accepted as Lycettitrigonia laeviuscula (Lycett, 1875) †
Species Trigonia laffittei Freneix & Busson, 1963 †
Species Trigonia lajoyei Leymerie, 1842 † accepted as Lycettitrigonia longa (Agassiz, 1840) †
Species Trigonia lamarckii J. E. Gray, 1838 accepted as Neotrigonia lamarckii (J. E. Gray, 1838)
Species Trigonia lamarckii Matheron, 1843 † accepted as Oistotrigonia lamarckii (Matheron, 1843) †
Species Trigonia lamberti Petitclerc, 1900 †
Species Trigonia langrunensis Bigot, 1893 † accepted as Cotswoldella langrunensis (Bigot, 1893) †
Species Trigonia lata Benett, 1831 †
Species Trigonia latiarealis Saveliev, 1960 †
Species Trigonia laufonensis Rollier, 1912 †
Species Trigonia leana Gabb, 1877 † accepted as Yaadia leana (Gabb, 1877) †
Species Trigonia leanzai Lambert, 1944 †
Species Trigonia leblanci de Loriol, 1874 †
Species Trigonia leckenbyi Lycett, 1874 †
Species Trigonia legayi Cossmann, 1912 †
Species Trigonia lennieri Bigot, 1893 †
Species Trigonia leonhardi Strand, 1928 †
Species Trigonia lepida R. A. Philippi, 1899 † accepted as Weaverella lepida (R. A. Philippi, 1899) †
Species Trigonia letteroni de Loriol, 1868 †
Species Trigonia leucothea R. A. Philippi, 1899 †
Species Trigonia levyi H. A. Leanza, 1993 †
Species Trigonia lewisi Blanckenhorn, 1890 † accepted as Levantotrigonia lewisi (Blanckenhorn, 1890) †
Species Trigonia libanensis Krumbeck, 1905 †
Species Trigonia libanotica H. E. Vokes, 1946 † accepted as Syrotrigonia libanotica (H. E. Vokes, 1946) †
Species Trigonia lidiae Mordvilko †
Species Trigonia limbata A. d'Orbigny, 1844 † accepted as Scabrotrigonia limbata (A. d'Orbigny, 1844) †
Species Trigonia linearis Münster, 1834 †
Species Trigonia lineata C. Moore, 1870 †
Species Trigonia lineolata Agassiz, 1840 †
Species Trigonia lingonensis Dumortier, 1869 † accepted as Liotrigonia lingonensis (Dumortier, 1869) †
Species Trigonia literata G. Young & J. Bird, 1828 †
Species Trigonia littlei Frebold, 1959 †
Species Trigonia loewinsonlessingi Renngarten, 1926 † accepted as Myophorella loewinsonlessingi (Renngarten, 1926) †
Species Trigonia longa Agassiz, 1840 † accepted as Lycettitrigonia longa (Agassiz, 1840) †
Species Trigonia longiloba Jimbo, 1894 † accepted as Metacanthotrigonia longiloba (Jimbo, 1894) †
Species Trigonia longirostris A. d'Orbigny, 1850 †
Species Trigonia longissima Staesche, 1932 †
Species Trigonia loockiensis Strand, 1928 †
Species Trigonia lorentii Dana, 1849 † accepted as Incagonia lorentii (Dana, 1849) †
Species Trigonia lorioli Choffat, 1885 †
Species Trigonia losadai H. A. Leanza, 1993 †
Species Trigonia louisi Strand, 1928 † accepted as Trigonia deslongchampsii Munier-Chalmas, 1865 †
Species Trigonia loutfyi Abbass, 1962 † accepted as Valenciella loutfyi (Abbass, 1962) †
Species Trigonia ludovicae Briart & Cornet, 1868 † accepted as Bacatigonia ludovicae (Briart & Cornet, 1868) †
Species Trigonia lusitanica Sharpe, 1850 † accepted as Myophorella lusitanica (Sharpe, 1850) †
Species Trigonia lycettensis Strand, 1928 †
Species Trigonia lycetti Gottsche, 1878 †
Species Trigonia lycettii Walford, 1885 † accepted as Trigonia walfordensis Strand, 1928 †
Species Trigonia lycettii Bigot, 1893 †
Species Trigonia lyrata Deshayes, 1858 † accepted as Trigonia literata G. Young & J. Bird, 1828 †
Species Trigonia lyrodontis Strand, 1928 †
Species Trigonia macphersoni Choffat, 1885 †
Species Trigonia macrorrhyncha R. A. Philippi, 1899 †
Species Trigonia mactroides R. A. Philippi, 1899 †
Species Trigonia maestrichtiana Briart, 1888 † accepted as Oistotrigonia maestrichtiana (Briart, 1888) †
Species Trigonia magharensis Abbass, 1962 † accepted as Levantotrigonia magharensis (Abbass, 1962) †
Species Trigonia magna Benett, 1831 †
Species Trigonia magnifica J. Roemer, 1911 †
Species Trigonia major A. d'Orbigny, 1850 †
Species Trigonia malladae Choffat, 1885 † accepted as Terrypoultoniella malladae (Choffat, 1885) †
Species Trigonia malladai [sic] † accepted as Trigonia malladae Choffat, 1885 †
Species Trigonia maloneana Stoyanow, 1949 † accepted as Stoyanowella maloneana (Stoyanow, 1949) †
Species Trigonia maltonensis Arkell, 1936 †
Species Trigonia mamillata Kitchin, 1903 † accepted as Steinmanella mamillata (Kitchin, 1903) †
Species Trigonia manflarum R. A. Philippi, 1899 †
Species Trigonia manflatis Strand, 1928 †
Species Trigonia mangyshlakensis Luppov, 1932 † accepted as Quadratotrigonia mangyshlakensis (Luppov, 1932) †
Species Trigonia manseli Lycett, 1874 † accepted as Laevitrigonia manseli (Lycett, 1874) †
Species Trigonia margarita Meneghini, 1880 †
Species Trigonia margaritacea Lamarck, 1804 accepted as Neotrigonia margaritacea (Lamarck, 1804)
Species Trigonia margaritacea Lamarck, 1804 sensu Bednall, 1878 accepted as Neotrigonia bednalli (Verco, 1907)
Species Trigonia margaritifera J. Böhm, 1904 † accepted as Myophorigonia margaritifera (J. Böhm, 1904) †
Species Trigonia marginata Damon, 1860 †
Species Trigonia marionensis Stephenson, 1923 † accepted as Gabbigonia marionensis (Stephenson, 1923) †
Species Trigonia marshalli Strand, 1928 †
Species Trigonia marumbiana Skwarko, 1966 †
Species Trigonia marwicki C. A. Fleming, 1987 †
Species Trigonia matapuana Krenkel, 1911 † accepted as Indotrigonia matapuana (Krenkel, 1911) †
Species Trigonia mathewsi E. F. Richards, 1947 † accepted as Incagonia mathewsi (E. F. Richards, 1947) †
Species Trigonia matronensis de Loriol, 1872 †
Species Trigonia matyasovszkyi Hofmann, 1912 †
Species Trigonia maudensis Whiteaves, 1884 † accepted as Apiotrigonia maudensis (Whiteaves, 1884) †
Species Trigonia maxima Agassiz, 1840 †
Species Trigonia mearnsi Stoyanow, 1949 † accepted as Cochisella mearnsi (Stoyanow, 1949) †
Species Trigonia medlycotti Damon, 1884 †
Species Trigonia melhasei F. M. Anderson, 1958 † accepted as Scabrotrigonia melhasei (F. M. Anderson, 1958) †
Species Trigonia meriani Agassiz, 1840 † accepted as Trigonia reticulata Agassiz, 1840 †
Species Trigonia meridiana H. Woods, 1917 † accepted as Eselaevitrigonia meridiana (H. Woods, 1917) †
Species Trigonia meronitzensis Strand, 1928 †
Species Trigonia mesembria Tenison Woods, 1883 †
Species Trigonia metzensis Strand, 1928 †
Species Trigonia meyeri Lycett, 1875 † accepted as Noelmorrisia meyeri (Lycett, 1875) †
Species Trigonia micheloti de Loriol, 1866 †
Species Trigonia micippe R. A. Philippi, 1899 †
Species Trigonia microscopica [sic] †
Species Trigonia migeodi L. R. Cox, 1965 †
Species Trigonia mindoroensis Hayasaka, 1943 †
Species Trigonia minor Litschkov, 1912 † accepted as Litschkovitrigonia minor (Litschkov, 1912) †
Species Trigonia minuta Stoliczka, 1871 † accepted as Nanotrigonia minuta (Stoliczka, 1870) †
Species Trigonia minuta R. A. Philippi, 1899 †
Species Trigonia mirandaensis Lambert, 1944 †
Species Trigonia miriana Skwarko, 1963 † accepted as Skwarkoella miriana (Skwarko, 1963) †
Species Trigonia miyakonis Strand, 1928 †
Species Trigonia modesta Tate & Blake, 1876 †
Species Trigonia modesta Moberg, 1888 † accepted as Luciniola limbata (Terquem & Piette, 1868) †
Species Trigonia molengraaffi R. B. Newton, 1903 †
Species Trigonia mollesensis Lambert, 1944 †
Species Trigonia monilifera Agassiz, 1840 † accepted as Trigonia reticulata Agassiz, 1840 †
Species Trigonia montanaensis Meek, 1873 †
Species Trigonia monthiersi Munier-Chalmas, 1882 †
Species Trigonia mooreana Gabb, 1861 † accepted as Praescabrotrigonia mooreana (Gabb, 1861) †
Species Trigonia moorei Lycett, 1870 † accepted as Coxitrigonia moorei (Lycett, 1870) †
Species Trigonia mordvilkoae Yanin, 1957 †
Species Trigonia moreli Munier-Chalmas, 1882 †
Species Trigonia moretoni J. Morris & Lycett, 1853 †
Species Trigonia moriana Yehara, 1927 † accepted as Metacanthotrigonia moriana (Yehara, 1927) †
Species Trigonia morieri Bigot, 1893 †
Species Trigonia morrisiana Strand, 1928 †
Species Trigonia mortoni Whitfield, 1885 † accepted as Tennessiella thoracica (S. G. Morton, 1834) †
Species Trigonia moutierensis Lycett, 1872 † accepted as Neustriella moutierensis (Lycett, 1872) †
Species Trigonia muelleri Dietrich, 1933 † accepted as Rinetrigonia muelleri (Dietrich, 1933) †
Species Trigonia muennichi R. A. Philippi, 1899 †
Species Trigonia multituberculata Litschkov, 1912 † accepted as Litschkovitrigonia multituberculata (Litschkov, 1912) †
Species Trigonia munieri Hébert, 1865 †
Species Trigonia munita Cragin, 1905 †
Species Trigonia nalivkini Tuchkov, 1956 †
Species Trigonia naltschikensis Mordvilko, 1949 † accepted as Tamaragonia naltschikensis (Mordvilko, 1949) †
Species Trigonia nana Eichwald, 1871 †
Species Trigonia nana R. A. Philippi, 1899 † accepted as Trigonia manflatis Strand, 1928 †
Species Trigonia narzanensis Mordvilko, 1960 †
Species Trigonia nasuta Etheridge, 1872 † accepted as Neopisthotrigonia nasuta (Etheridge, 1872) †
Species Trigonia naumanni Yehara, 1923 † accepted as Nipponitrigonia naumanni (Yehara, 1923) †
Species Trigonia naviformis Hyatt, 1892 † accepted as Scaphotrigonia naviformis (Hyatt, 1892) †
Species Trigonia navis Lamarck, 1819 † accepted as Scaphotrigonia navis (Lamarck, 1819) †
Species Trigonia neglecta Guéranger, 1867 † accepted as Lycettitrigonia affinis (J. Sowerby, 1818) †
Species Trigonia neocomica Strand, 1928 †
Species Trigonia neozelanica Suter, 1915 † accepted as Verticordia neozelanica (Suter, 1915) †
Species Trigonia nepos Paulcke, 1903 † accepted as Paulckella nepos (Paulcke, 1903) †
Species Trigonia neptuni A. d'Orbigny, 1850 †
Species Trigonia nereis A. d'Orbigny, 1850 † accepted as Apiotrigonia nereis (A. d'Orbigny, 1850) †
Species Trigonia nereis R. A. Philippi, 1899 † accepted as Trigonia tinguiriricae Strand, 1928 †
Species Trigonia neumayri Choffat, 1885 †
Species Trigonia neumayri Yehara, 1923 † accepted as Rutitrigonia yeharai T. Kobayashi, 1954 †
Species Trigonia neuquensis Burckhardt, 1903 † accepted as Garatella neuquensis (Burckhardt, 1903) †
Species Trigonia newcombei E. L. Packard, 1921 † accepted as Poultoniella newcombei (E. L. Packard, 1921) †
Species Trigonia nikschitschi Mordvilko †
Species Trigonia niongalensis E. Lange, 1914 † accepted as Tanzanitrigonia niongalensis (E. Lange, 1914) †
Species Trigonia nitida Kitchin, 1903 †
Species Trigonia nobilis A. Adams, 1854 accepted as Neotrigonia margaritacea (Lamarck, 1804)
Species Trigonia nodosa J. De C. Sowerby, 1826 † accepted as Quadratotrigonia nodosa (J. De C. Sowerby, 1826) †
Species Trigonia nodulosa Lamarck, 1801 †
Species Trigonia northamptonensis Walford, 1885 †
Species Trigonia notata Agassiz, 1840 †
Species Trigonia nux R. A. Philippi, 1899 †
Species Trigonia obesa R. A. Philippi, 1899 †
Species Trigonia obliqua Hyatt, 1892 †
Species Trigonia oblonga Yanin & Bogdanova, 2017 †
Species Trigonia oblongotuberculata Litschkov, 1912 † accepted as Litschkovitrigonia oblongotuberculata (Litschkov, 1912) †
Species Trigonia obtusa Hupé, 1854 †
Species Trigonia oehlerti Bigot, 1893 †
Species Trigonia ogawai Yehara, 1923 † accepted as Tamuragonia ogawai (Yehara, 1923) †
Species Trigonia oomia Strand, 1928 †
Species Trigonia opistolophophora Lambert, 1944 † accepted as Antutrigonia opistolophophora (Lambert, 1944) †
Species Trigonia orbignyana Lissón, 1930 † accepted as Buchotrigonia orbignyana (Lissón, 1930) †
Species Trigonia oreas R. A. Philippi, 1899 †
Species Trigonia orientalis Forbes, 1845 † accepted as Jaitlygonia orientalis (Forbes, 1845) †
Species Trigonia orientalis Douvillé, 1916 † accepted as Trigonia douvillei El Din, 1955 †
Species Trigonia ornata A. d'Orbigny, 1844 † accepted as Noelmorrisia ornata (A. d'Orbigny, 1844) †
Species Trigonia oustaleti de Loriol, 1874 †
Species Trigonia ovalis R. A. Philippi, 1899 †
Species Trigonia ovallei R. A. Philippi, 1899 †
Species Trigonia ovata Litschkov, 1912 † accepted as Litschkovitrigonia ovata (Litschkov, 1912) †
Species Trigonia oviedensis Lycett, 1881 †
Species Trigonia oyamoensis Welter, 1933 †
Species Trigonia packardi F. M. Anderson, 1958 † accepted as Columbitrigonia packardi (F. M. Anderson, 1958) †
Species Trigonia padernensis Petter-Receveur, 1955 † accepted as Quadratotrigonia padernensis (Petter-Receveur, 1955) †
Species Trigonia painei Lycett, 1874 †
Species Trigonia palaeopatagonica Piatnitzky, 1938 †
Species Trigonia palmata Leymerie, 1842 † accepted as Lutetigonia palmata (Leymerie, 1842) †
Species Trigonia pandicosta Meek, 1864 †
Species Trigonia papillata Agassiz, 1840 † accepted as Trigonia reticulata Agassiz, 1840 †
Species Trigonia papuana Glaessner, 1958 † accepted as Papuagonia papuana (Glaessner, 1958) †
Species Trigonia paradisensis Lissón, 1907 † accepted as Incagonia paradisensis (Lissón, 1907) †
Species Trigonia paradoxa Agassiz, 1840 †
Species Trigonia parcinoda Lycett, 1872 † accepted as Retetrigonia parcinoda (Lycett, 1872) †
Species Trigonia parkinsonii Agassiz, 1840 †
Species Trigonia parva Kitchin, 1903 † accepted as Trigonia kitchini Strand, 1928 †
Species Trigonia parva Forbes, 1844 †
Species Trigonia parva Brüggen, 1910 † accepted as Trigonia brueggeni Strand, 1928 †
Species Trigonia parvula Agassiz, 1840 † accepted as Trigonia reticulata Agassiz, 1840 †
Species Trigonia parvula Reuss, 1846 † accepted as Trigonia meronitzensis Strand, 1928 †
Species Trigonia patagonica Feruglio, 1937 †
Species Trigonia patchamensis Fürsich & Heinze, 1998 †
Species Trigonia patonensis Basse, 1931 † accepted as Elianegonia patonensis (Basse, 1931) †
Species Trigonia paucicosta Lycett, 1874 †
Species Trigonia paucicostata Burwash, 1914 †
Species Trigonia pavlovi Strémooukhov, 1897 † accepted as Oistotrigonia pavlovi (Strémooukhov, 1897) †
Species Trigonia pcelincevae Saveliev, 1960 †
Species Trigonia pectinata Lamarck, 1819 accepted as Neotrigonia margaritacea (Lamarck, 1804)
Species Trigonia pellati Munier-Chalmas, 1865 †
Species Trigonia peninsularis Coquand, 1863 †
Species Trigonia pennata J. Sowerby, 1819 † accepted as Apiotrigonia pennata (J. Sowerby, 1819) †
Species Trigonia percaudata Rollier, 1913 † accepted as Eurotrigonia percaudata (Rollier, 1913) †
Species Trigonia perlata Agassiz, 1840 † accepted as Myophorella perlata (Agassiz, 1840) †
Species Trigonia perrinsmithi F. M. Anderson, 1958 † accepted as Yaadia whiteavesi (E. L. Packard, 1921) †
Species Trigonia perroni Étallon, 1864 †
Species Trigonia petasoides Wetzel, 1911 †
Species Trigonia phillipsi J. Morris & Lycett, 1853 †
Species Trigonia pichimoncolensis Lambert, 1944 † accepted as Lambertrigonia pichimoncolensis (Lambert, 1944) †
Species Trigonia pickeringensis Arkell, 1930 †
Species Trigonia picta Agassiz, 1840 †
Species Trigonia picteti Coquand, 1863 † accepted as Zulutrigonia picteti (Coquand, 1863) †
Species Trigonia picunensis C. E. Weaver, 1931 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia pinzasii Welter, 1913 †
Species Trigonia piriformis Mordvilko, 1932 † accepted as Mangyschlakella piriformis (Mordvilko, 1932) †
Species Trigonia pizcuetana Vilanova y Piera, 1863 † accepted as Buchotrigonia pizcuetana (Vilanova y Piera, 1863) †
Species Trigonia plagia R. A. Philippi, 1899 †
Species Trigonia plana Repin, 2013 †
Species Trigonia plicata Agassiz, 1840 †
Species Trigonia plicatocostata Nyst & Galeotti, 1840 † accepted as Notoscabrotrigonia plicatocostata (Nyst & Galeotti, 1840) †
Species Trigonia plumasensis Hyatt, 1892 † accepted as Californigonia plumasensis (Hyatt, 1892) †
Species Trigonia pocilliformis Yokoyama, 1891 † accepted as Notoscabrotrigonia pocilliformis (Yokoyama, 1891) †
Species Trigonia popelaievi Strémooukhov, 1897 †
Species Trigonia portlandensis L. R. Cox, 1925 †
Species Trigonia portlandica (J. De C. Sowerby, 1836) †
Species Trigonia postera Quenstedt, 1857 †
Species Trigonia poststriata Whitfield & Hovey, 1906 †
Species Trigonia praecostata Branco, 1879 †
Species Trigonia praelonga Gottsche, 1878 †
Species Trigonia praelonga Loock, 1886 † accepted as Trigonia loockiensis Strand, 1928 †
Species Trigonia praescabroidea Jaworski, 1915 †
Species Trigonia praestriata Cragin, 1905 †
Species Trigonia primaeva Troedsson, 1951 †
Species Trigonia problematica Münster, 1839 †
Species Trigonia prodigiosa Strand, 1928 †
Species Trigonia producta Lycett, 1860 †
Species Trigonia producta Terquem & Jourdy, 1869 †
Species Trigonia progonos Paulcke, 1903 †
Species Trigonia propinqua Kitchin, 1903 †
Species Trigonia prora Kitchin, 1903 †
Species Trigonia proscabra Cragin, 1905 †
Species Trigonia proserpina A. d'Orbigny, 1850 † accepted as Orthotrigonia proserpina (A. d'Orbigny, 1850) †
Species Trigonia pseudoacuta Dykan, 1990 †
Species Trigonia pseudobronni Strand, 1928 †
Species Trigonia pseudocaudata P. Thomas & A. Péron, 1889 † accepted as Notoscabrotrigonia peroni (Freneix, 1972) †
Species Trigonia pseudocaudata Hector, 1886 † accepted as Pterotrigonia pseudocaudata (Hector, 1886) †
Species Trigonia pseudocrenulata Noetling, 1886 † accepted as Arabitrigonia pseudocrenulata (Noetling, 1886) †
Species Trigonia pseudocundata Hector, 1886 † accepted as Haumurigonia pseudocaudata (Hector, 1886) †
Species Trigonia pseudocyprina Contejean, 1860 †
Species Trigonia pseudoexcentrica Hoppe, 1922 † accepted as Lycettitrigonia pseudoexcentrica (Hoppe, 1922) †
Species Trigonia pseudoindica Arkhanguelsky, 1916 † accepted as Turanigonia pseudoindica (Arkhanguelsky, 1916) †
Species Trigonia pseudomeriani Choffat, 1885 †
Species Trigonia pseudopapillata Dykan, 1990 †
Species Trigonia pseudoquadrata Arldt, 1922 †
Species Trigonia pseudosinuosa Brun & Chatelet, 1926 †
Species Trigonia pseudospinosa de Loriol, 1882 † accepted as Oistotrigonia pseudospinosa (de Loriol, 1882) †
Species Trigonia pseudotransitoria Litschkov, 1932 † accepted as Litschkovitrigonia pseudotransitoria (Litschkov, 1932) †
Species Trigonia pulchella Agassiz, 1840 †
Species Trigonia pulchella Reuss, 1846 † accepted as Trigonia reussi Strand, 1928 †
Species Trigonia pulchra Kitchin, 1903 †
Species Trigonia pullus J. De C. Sowerby, 1826 † accepted as Cornbrashella pullus (J. de C. Sowerby, 1826) †
Species Trigonia pumila Nilsson, 1827 † accepted as Oistotrigonia pumila (Nilsson, 1827) †
Species Trigonia puschi Deshayes, 1858 †
Species Trigonia pusilla R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia pustulata T. Brown, 1849 †
Species Trigonia pustulosa Nagao, 1930 † accepted as Metacanthotrigonia pustulosa (Nagao, 1930) †
Species Trigonia pygoscelium Wilckens, 1910 † accepted as Henrywoodsia pygoscelium (Wilckens, 1910) †
Species Trigonia pyrrha A. d'Orbigny, 1850 † accepted as Oistotrigonia spinosa (Parkinson, 1811) †
Species Trigonia quadrangularis J. Hall & Whitfield, 1877 †
Species Trigonia quadrata Agassiz, 1840 † accepted as Trigonia deslongchampsii Munier-Chalmas, 1865 †
Species Trigonia quadrata J. De C. Sowerby, 1836 † accepted as Neoquadratotrigonia daedalea (Parkinson, 1811) †
Species Trigonia quenstedti Quenstedt, 1857 †
Species Trigonia quenstedtiella Strand, 1928 †
Species Trigonia quinquecostata [sic] †
Species Trigonia radiata Étallon, 1864 †
Species Trigonia radiata Benett, 1831 †
Species Trigonia radixscripta Lambert, 1944 † accepted as Andivaugonia radixscripta (Lambert, 1944) †
Species Trigonia ramsayii T. Wright, 1856 †
Species Trigonia ranvilliana Bigot, 1893 † accepted as Cotswoldella ranvilliana (Bigot, 1893) †
Species Trigonia raricostata Moesch, 1867 †
Species Trigonia reboursi Riche, 1904 †
Species Trigonia rectangularis Gottsche, 1878 †
Species Trigonia recticosta Lycett, 1872 † accepted as Orthotrigonia recticosta (Lycett, 1872) †
Species Trigonia recticostata Burwash, 1914 †
Species Trigonia recurva Kitchin, 1903 † accepted as Mayesella recurva (Kitchin, 1903) †
Species Trigonia reesidei Stoyanow, 1949 † accepted as Buchotrigonia reesidei (Stoyanow, 1949) †
Species Trigonia regina Wilckens, 1910 † accepted as Eselaevitrigonia regina (Wilckens, 1910) †
Species Trigonia regularicostata Blanckenhorn, 1890 †
Species Trigonia remota Kitchin, 1903 †
Species Trigonia renevieri Choffat, 1885 †
Species Trigonia reniforme Burwash, 1914 † accepted as Trigonia reniformis Burwash, 1914 †
Species Trigonia reniformis Burwash, 1914 †
Species Trigonia resoluta Stoyanow, 1949 † accepted as Cochisella resoluta (Stoyanow, 1949) †
Species Trigonia reticulata Agassiz, 1840 †
Species Trigonia retrorsa Kitchin, 1903 † accepted as Opisthotrigonia retrorsa (Kitchin, 1903) †
Species Trigonia reussi Strand, 1928 †
Species Trigonia revoili Rochebrune, 1882 †
Species Trigonia rhombifera Romanovsky, 1890 † accepted as Bogdanovaella rhombifera (Romanovsky, 1890) †
Species Trigonia ribeiroi Choffat, 1885 †
Species Trigonia richei Strand, 1928 †
Species Trigonia rigauxi Cossmann, 1911 †
Species Trigonia rigauxiana Munier-Chalmas, 1865 †
Species Trigonia robinaldina A. d'Orbigny, 1844 † accepted as Grandigonia robinaldina (A. d'Orbigny, 1844) †
Species Trigonia roelligiana Maas, 1895 †
Species Trigonia roemeri Agassiz, 1840 †
Species Trigonia rogersi Kitchin, 1908 † accepted as Pterotrigonioides rogersi (Kitchin, 1908) †
Species Trigonia rolandi Cross, 1875 †
Species Trigonia rolli Piatnitzky, 1938 † accepted as Iotrigonia rolli (Piatnitzky, 1938) †
Species Trigonia romanovskii Arkhanguelsky, 1916 † accepted as Romanovskiella romanovskii (Arkhanguelsky, 1916) †
Species Trigonia romanowskyensis Strand, 1928 † accepted as Rutitrigonia romanowskyensis (Strand, 1928) †
Species Trigonia rostrum Agassiz, 1840 †
Species Trigonia rottweilensis Strand, 1928 †
Species Trigonia rotundata Yokoyama, 1891 † accepted as Nipponitrigonia kikuchiana (Yokoyama, 1891) †
Species Trigonia rotundata de Loriol, 1861 †
Species Trigonia rotundata Romanovsky, 1880 † accepted as Trigonia romanowskyensis Strand, 1928 †
Species Trigonia roxane Borne, 1891 †
Species Trigonia royeri de Loriol, 1872 †
Species Trigonia rudicostata Cragin, 1905 †
Species Trigonia rudis Parkinson, 1811 † accepted as Neoquadratotrigonia rudis (Parkinson, 1811) †
Species Trigonia rugosa Lamarck, 1819 †
Species Trigonia rugosa Parkinson, 1811 †
Species Trigonia rugosa R. A. Philippi, 1899 †
Species Trigonia rugosicostata Saveliev, 1960 †
Species Trigonia rupellensis A. d'Orbigny, 1850 †
Species Trigonia saavedra Stoyanow, 1949 † accepted as Cochisella saavedra (Stoyanow, 1949) †
Species Trigonia sabae Blanckenhorn, 1890 †
Species Trigonia sachalinica Strand, 1928 †
Species Trigonia sagawai Yehara, 1927 † accepted as Nipponitrigonia sagawai (Yehara, 1927) †
Species Trigonia sakakurai Yehara, 1923 † accepted as Metacanthotrigonia sakakurai (Yehara, 1923) †
Species Trigonia sakamotoensis Yehara, 1921 † accepted as Nipponitrigonia sakamotoensis (Yehara, 1921) †
Species Trigonia sakawaensis Strand, 1928 †
Species Trigonia saltillensis Wolleben, 1977 †
Species Trigonia sampana Skwarko, 1967 †
Species Trigonia sanctaecrucis F.-J. Pictet & Campiche, 1866 † accepted as Lycettitrigonia sanctaecrucis (F.-J. Pictet & Campiche, 1866) †
Species Trigonia sauvagei de Loriol, 1874 †
Species Trigonia sawatai Yehara, 1923 † accepted as Himenourella sawatai (Yehara, 1923) †
Species Trigonia scabiosa Litschkov, 1912 †
Species Trigonia scabra Lamarck, 1819 † accepted as Scabrotrigonia scabra (Lamarck, 1819) †
Species Trigonia scabricola Lycett, 1875 † accepted as Notoscabrotrigonia scabricola (Lycett, 1875) †
Species Trigonia scapha Agassiz, 1840 † accepted as Tamaragonia scapha (Agassiz, 1840) †
Species Trigonia scarburgensis Lycett, 1863 †
Species Trigonia schwarzi G. Müller, 1900 † accepted as Tanzanitrigonia schwarzi (G. Müller, 1900) †
Species Trigonia sculpta (Lycett, 1853) †
Species Trigonia scuticulata [sic] † accepted as Trigonia denticulata Agassiz, 1840 †
Species Trigonia securiformis Cragin, 1893 †
Species Trigonia seeleyi Rigaux, 1892 †
Species Trigonia seguenzai Trevisan, 1937 † accepted as Tamaragonia seguenzai (Trevisan, 1937) †
Species Trigonia semicostata R. A. Philippi, 1899 † accepted as Anditrigonia eximia (R. A. Philippi, 1899) †
Species Trigonia semiculta Forbes, 1845 † accepted as Lycettitrigonia semiculta (Forbes, 1845) †
Species Trigonia semilunata R. A. Philippi, 1899 †
Species Trigonia semiornata A. d'Orbigny, 1846 †
Species Trigonia semisericea H. F. Blanford, 1864 †
Species Trigonia semiundulata McCoy, 1866 † accepted as Eotrigonia subundulata (H. M. Jenkins, 1865) †
Species Trigonia senex T. Kobayashi & Mori, 1954 † accepted as Magharitrigonia senex (Kobayashi & Mori, 1954) †
Species Trigonia seranensis Krumbeck, 1923 † accepted as Prorotrigonia seranensis (Krumbeck, 1923) †
Species Trigonia sexcostata F. A. Roemer, 1836 †
Species Trigonia sharpiana Lycett, 1874 †
Species Trigonia shepstonei Griesbach, 1871 † accepted as Acanthotrigonia shepstonei (Griesbach, 1871) †
Species Trigonia sibirzevi Strémooukhov, 1897 †
Species Trigonia signata Agassiz, 1840 †
Species Trigonia signicollina C. A. Fleming, 1987 †
Species Trigonia similis (Bronn, 1836) †
Species Trigonia sinuata Parkinson, 1811 † accepted as Lycettitrigonia eccentrica (Parkinson, 1811) †
Species Trigonia sinuosa Lamarck, 1819 †
Species Trigonia smeeii J. De C. Sowerby, 1840 † accepted as Indotrigonia smeeii (J. De C. Sowerby, 1840) †
Species Trigonia snaintonensis Lycett, 1877 † accepted as Orthotrigonia snaintonensis (Lycett, 1877) †
Species Trigonia sologureni Felix, 1891 †
Species Trigonia somaliensis Stefanini, 1939 †
Species Trigonia spaichingensis Strand, 1928 †
Species Trigonia spectabilis J. De C. Sowerby, 1826 † accepted as Neoquadratotrigonia spectabilis (J. De C. Sowerby, 1826) †
Species Trigonia spinifera A. d'Orbigny, 1850 † accepted as Orthotrigonia spinifera (A. d'Orbigny, 1850) †
Species Trigonia spinosa Parkinson, 1811 † accepted as Oistotrigonia spinosa (Parkinson, 1811) †
Species Trigonia spinulosa G. Young & J. Bird, 1828 † accepted as Promyophorella spinulosa (G. Young & J. Bird, 1828) †
Species Trigonia spinulosocostata Pethö, 1906 † accepted as Scabrotrigonia spinulosocostata (Pethö, 1906) †
Species Trigonia spissicostata Kitchin, 1903 † accepted as Ghuneriella spissicostata (Kitchin, 1903) †
Species Trigonia spitiensis Holdhaus, 1913 †
Species Trigonia splendida A. F. Leanza, 1941 † accepted as Splenditrigonia splendida (A. F. Leanza, 1941) †
Species Trigonia staffi E. Lange, 1914 † accepted as Megatrigonia staffi (E. Lange, 1914) †
Species Trigonia stantoni Stephenson, 1941 † accepted as Tennessiella stantoni (Stephenson, 1941) †
Species Trigonia steinmanni R. A. Philippi, 1899 † accepted as Weaverella steinmanni (R. A. Philippi, 1899) †
Species Trigonia steinmanni Lissón, 1930 † accepted as Incagonia mathewsi (E. F. Richards, 1947) †
Species Trigonia stelzneri Gottsche, 1878 †
Species Trigonia stiebeli S. A. Miller, 1881 †
Species Trigonia stolleyi R. T. Hill, 1893 † accepted as Notoscabrotrigonia stolleyi (R. T. Hill, 1893) †
Species Trigonia stolpi R. A. Philippi, 1899 †
Species Trigonia stowi Kitchin, 1908 † accepted as Iotrigonia stowi (Kitchin, 1908) †
Species Trigonia strangei A. Adams, 1854 accepted as Neotrigonia strangei (A. Adams, 1854)
Species Trigonia stremmei E. Lange, 1914 †
Species Trigonia striata J. Sowerby, 1819 †
Species Trigonia striatissima Bigot, 1893 †
Species Trigonia stricta Étallon, 1862 †
Species Trigonia sturgisensis Whitfield & Hovey, 1906 † accepted as Pseudapiotrigonia sturgisensis (Whitfield & Hovey, 1906) †
Species Trigonia subcarinata Ebray, 1858 †
Species Trigonia subconcentrica Étallon, 1863 †
Species Trigonia subcostata Leymerie, 1846 †
Species Trigonia subcrenulata A. d'Orbigny, 1842 † accepted as Notoscabrotrigonia tocaimaana (I. Lea, 1841) †
Species Trigonia subdaedalea Renngarten, 1926 † accepted as Saveligonia subdaedalea (Renngarten, 1926) †
Species Trigonia subetheridgei Mordvilko, 1956 †
Species Trigonia subexcentrica A. d'Orbigny, 1850 †
Species Trigonia subglobosa J. Morris & Lycett, 1853 †
Species Trigonia subhondeana Gillet, 1924 † accepted as Mediterraneotrigonia subhondeana (Gillet, 1924) †
Species Trigonia subinguschensis Mordvilko, 1960 †
Species Trigonia subkudakhurtensis Mordvilko †
Species Trigonia subliterata Münster, 1841 †
Species Trigonia subnaltschikensis Mordvilko, 1960 †
Species Trigonia subnodosa Mordvilko, 1952 †
Species Trigonia subnodosa Mordvilko [sic] †
Species Trigonia suborbicularis Forbes, 1845 † accepted as Jaitlygonia suborbicularis (Forbes, 1845) †
Species Trigonia subornata Yanin, 1957 †
Species Trigonia subovalis Jimbo, 1894 † accepted as Himenourella subovalis (Jimbo, 1894) †
Species Trigonia subpulchella A. d'Orbigny, 1850 †
Species Trigonia subspinosa [sic] †
Species Trigonia substriata Riche, 1904 † accepted as Trigonia richei Strand, 1928 †
Species Trigonia substriata Burmeister & Giebel, 1861 †
Species Trigonia substriatissima Kuljinskaja-Voronetz, 1936 †
Species Trigonia subtriangularis Wetzel, 1911 †
Species Trigonia subtrigona [sic] †
Species Trigonia subtruncata Étallon, 1864 †
Species Trigonia subtruncata Repman, 1963 †
Species Trigonia subundulata H. M. Jenkins, 1865 † accepted as Eotrigonia subundulata (H. M. Jenkins, 1865) †
Species Trigonia subventricosa Stanton, 1901 † accepted as Pisotrigonia subventricosa (Stanton, 1901) †
Species Trigonia suevi Strémooukhov, 1897 †
Species Trigonia suevica Quenstedt, 1857 † accepted as Clavotrigonia suevica (Quenstedt, 1857) †
Species Trigonia sulcata (Hermann, 1781) †
Species Trigonia sulcata Agassiz, 1840 † accepted as Trigonia hauterivica Strand, 1928 †
Species Trigonia sulcata Hector, 1874 † accepted as Pacitrigonia hanetiana hectori C. A. Fleming, 1987 †
Species Trigonia sulcataria Lamarck, 1819 † accepted as Apiotrigonia sulcataria (Lamarck, 1819) †
Species Trigonia sulcifera R. A. Philippi, 1899 †
Species Trigonia sultanuisi Arkhanguelsky, 1916 † accepted as Asiatotrigonia sultanuisi (Arkhanguelsky, 1916) †
Species Trigonia sumiyagura T. Kobayashi & Kaseno, 1947 †
Species Trigonia sundti R. A. Philippi, 1899 †
Species Trigonia suprabathonica J. B. Greppin, 1870 †
Species Trigonia suprajurensis Agassiz, 1840 †
Species Trigonia swindonensis J. F. Blake, 1880 †
Species Trigonia sydorenkoeremeievae Shheglova-Borodina, 1960 † accepted as Bobkovaella sydorenkoeremeievae (Shheglova-Borodina, 1960) †
Species Trigonia syrdariensis Arkhanguelsky, 1916 † accepted as Kyzylkumgonia syrdariensis (Arkhanguelsky, 1916) †
Species Trigonia syriaca Conrad, 1852 †
Species Trigonia tabacoensis Barthel, 1958 †
Species Trigonia taffi Cragin, 1893 † accepted as Cochisella taffi (Cragin, 1893) †
Species Trigonia tanganyicensis Aitken, 1961 †
Species Trigonia tapiai Lambert, 1944 † accepted as Frenguelliella chubutensis (Feruglio, 1934) †
Species Trigonia tatei Pritchard, 1895 † accepted as Trigonia intersitans Tate, 1896 †
Species Trigonia tatei Neumayr, 1882 †
Species Trigonia tealbyensis Lycett, 1875 † accepted as Pseudomyophorella tealbyensis (Lycett, 1875) †
Species Trigonia tealei L. R. Cox, 1937 † accepted as Coxitrigonia tealei (L. R. Cox, 1937) †
Species Trigonia tenuicosta Lycett, 1853 †
Species Trigonia tenuis Kitchin, 1903 † accepted as Trigonia oomia Strand, 1928 †
Species Trigonia tenuis R. A. Philippi, 1899 †
Species Trigonia tenuistriata R. A. Philippi, 1899 †
Species Trigonia tenuisulcata Dujardin, 1837 † accepted as Oistotrigonia tenuisulcata (Dujardin, 1837) †
Species Trigonia tenuitexta Lycett, 1874 †
Species Trigonia tepsichensis Mordvilko, 1937 †
Species Trigonia tepsikhaensis Bogdanova & Yanin, 2004 †
Species Trigonia tepsikhaensis Mordvilko, 1960 †
Species Trigonia terquemi Benecke, 1905 †
Species Trigonia teruelensis Strand, 1928 †
Species Trigonia tetragona Stoppani, 1857 †
Species Trigonia texana Conrad, 1857 †
Species Trigonia textilis E. J. Lees, 1934 †
Species Trigonia thetis R. A. Philippi, 1899 †
Species Trigonia thevenini de Loriol, 1904 †
Species Trigonia thierachensis J.-C. Fischer, 1969 †
Species Trigonia thomarensis Choffat, 1885 †
Species Trigonia thoracica S. G. Morton, 1834 † accepted as Tennessiella thoracica (S. G. Morton, 1834) †
Species Trigonia thurmanni Contejean, 1860 †
Species Trigonia tinguiriricae Strand, 1928 †
Species Trigonia tinguiriricaensis Strand, 1928 †
Species Trigonia tocaimaana I. Lea, 1841 † accepted as Trigonia tocaimana I. Lea, 1840 †
Species Trigonia tocaimana I. Lea, 1840 † accepted as Notoscabrotrigonia tocaimana (I. Lea, 1840) †
Species Trigonia tombecki de Loriol, 1872 †
Species Trigonia torrevedrasi Strand, 1928 †
Species Trigonia toyamai Yehara, 1923 † accepted as Tamuragonia toyamai (Yehara, 1923) †
Species Trigonia trafalgarensis P. S. Warren, 1932 †
Species Trigonia transatlantica Behrendsen, 1892 † accepted as Notoscabrotrigonia transatlantica (Behrendsen, 1892) †
Species Trigonia transitoria Steinmann, 1881 † accepted as Transitrigonia transitoria (Steinmann, 1881) †
Species Trigonia transversa Bornemann, 1856 † accepted as Myophoria transversa (Bornemann, 1856) †
Species Trigonia trapeziformis Kitchin, 1903 † accepted as Kitchingonia trapeziformis (Kitchin, 1903) †
Species Trigonia trapezoidea R. A. Philippi, 1899 †
Species Trigonia triangularis R. A. Philippi, 1899 †
Species Trigonia trigona W. Waagen, 1867 †
Species Trigonia tripartita Forbes, 1851 † accepted as Trigonia (Vaugonia) tripartita Forbes, 1851 †
Species Trigonia triquetra Seebach, 1864 †
Species Trigonia trita R. A. Philippi, 1899 †
Species Trigonia troniensis Reis, 1898 †
Species Trigonia trouvillensis Strand, 1928 †
Species Trigonia truncata Agassiz, 1840 †
Species Trigonia tryoniana Gabb, 1864 † accepted as Popenoella tryoniana (Gabb, 1864) †
Species Trigonia tuarensis Saveliev, 1960 †
Species Trigonia tuberculata Agassiz, 1840 † accepted as Promyophorella tuberculata (Agassiz, 1840) †
Species Trigonia tuberculifera Stoliczka, 1871 † accepted as Rinetrigonia tuberculifera (Stoliczka, 1871) †
Species Trigonia tuberculosa Lycett, 1850 †
Species Trigonia tuberosa R. A. Philippi, 1899 †
Species Trigonia tubulifera Tate, 1885 † accepted as Eotrigonia tubulifera (Tate, 1885) †
Species Trigonia tumida Kitchin, 1903 †
Species Trigonia tunsaensis Mordvilko †
Species Trigonia turcmenensis Arkhanguelsky, 1916 † accepted as Kyzylkumgonia turcmenensis (Arkhanguelsky, 1916) †
Species Trigonia turkestanensis Arkhangelsky, 1916 † accepted as Turkestanella turkestanensis (Arkhangelsky, 1916) †
Species Trigonia umkwelanensis Etheridge, 1904 † accepted as Linotrigonia umkwelanensis (Etheridge, 1904) †
Species Trigonia undulata R. A. Philippi, 1899 † accepted as Trigonia tinguiriricaensis Strand, 1928 †
Species Trigonia undulata Fromherz, 1838 †
Species Trigonia undulatocostata Blanckenhorn, 1890 † accepted as Lycettitrigonia undulatocostata (Blanckenhorn, 1890) †
Species Trigonia uniclavata Cossmann, 1922 †
Species Trigonia unioniformis R. A. Philippi, 1899 †
Species Trigonia uniophora J. E. Gray, 1847 accepted as Neotrigonia uniophora (J. E. Gray, 1847)
Species Trigonia upwarensis Lycett, 1875 † accepted as Oistotrigonia upwarensis (Lycett, 1875) †
Species Trigonia utrillatis Strand, 1928 † accepted as Mediterraneotrigonia decora (Stoliczka, 1871) †
Species Trigonia vaelsiensis J. Böhm, 1884 † accepted as Scabrotrigonia vaelsiensis (J. Böhm, 1884) †
Species Trigonia valentina Vilanova y Piera, 1887 † accepted as Mediterraneotrigonia decora (Stoliczka, 1871) †
Species Trigonia valfinensis de Loriol, 1888 †
Species Trigonia variegata Credner, 1863 †
Species Trigonia vau Sharpe, 1856 † accepted as Mayesella vau (Sharpe, 1856) †
Species Trigonia vcostata Lycett, 1850 † accepted as Vaugonia vcostata (Lycett, 1850) †
Species Trigonia vectiana Lycett, 1875 † accepted as Eurotrigonia vectiana (Lycett, 1875) †
Species Trigonia veneriformis R. A. Philippi, 1899 †
Species Trigonia verneuili Vilanova y Piera, 1863 † accepted as Mediterraneotrigonia verneuili (Vilanova y Piera, 1863) †
Species Trigonia verrucosa Credner, 1863 †
Species Trigonia verticulata [sic] † accepted as Trigonia reticulata Agassiz, 1840 †
Species Trigonia vertistriata Skwarko, 1963 †
Species Trigonia vicaryana Lycett, 1875 † accepted as Oistotrigonia vicaryana (Lycett, 1875) †
Species Trigonia vilanovae Strand, 1928 †
Species Trigonia villersensis Bigot, 1895 †
Species Trigonia volckmanni R. A. Philippi, 1899 †
Species Trigonia voltzii Agassiz, 1840 †
Species Trigonia vscripta Kitchin, 1903 † accepted as Iotrigonia vscripta (Kitchin, 1903) †
Species Trigonia vyschetzkii Cragin, 1893 † accepted as Stoyanowella vyschetzkii (Cragin, 1893) †
Species Trigonia waiparensis H. Woods, 1917 † accepted as Henrywoodsia waiparensis (H. Woods, 1917) †
Species Trigonia walfordensis Strand, 1928 †
Species Trigonia walfordi Lycett, 1883 †
Species Trigonia weaveri Stoyanow, 1949 † accepted as Tanzanitrigonia weaveri (Stoyanow, 1949) †
Species Trigonia weberi Arkhanguelsky, 1916 † accepted as Buchotrigonia weberi (Arkhanguelsky, 1916) †
Species Trigonia wendleri M. Whitney, 1952 † accepted as Praescabrotrigonia mooreana (Gabb, 1861) †
Species Trigonia wetzeliana Strand, 1928 †
Species Trigonia whateleyae Buch, 1845 † accepted as Costatoria whateleyae (Buch, 1845) †
Species Trigonia wheelerensis F. M. Anderson, 1958 † accepted as Yaadia leana (Gabb, 1877) †
Species Trigonia whitneyi M. Whitney, 1952 † accepted as Notoscabrotrigonia whitneyi (M. Whitney, 1852) †
Species Trigonia wiedmanni H. A. Leanza & Garate Zubillaga, 1987 †
Species Trigonia wightensis Strand, 1928 †
Species Trigonia wilckensi Feruglio, 1937 † accepted as Haumurigonia windhauseniana (Wilckens, 1921) †
Species Trigonia williamsi R. A. Philippi, 1899 †
Species Trigonia williamsoni Lycett, 1874 †
Species Trigonia windhauseniana Wilckens, 1921 † accepted as Haumurigonia windhauseniana (Wilckens, 1921) †
Species Trigonia windoesi Lycett, 1883 †
Species Trigonia witchelli Lycett, 1877 †
Species Trigonia woodwardi Lycett, 1872 †
Species Trigonia yeharai Saeki, 1925 †
Species Trigonia yokoyamai Yehara, 1915 †
Species Trigonia zieteni É. Greppin, 1899 †
Species Trigonia zieteniella Strand, 1928 †
Species Trigonia zitteli Branco, 1879 †
Species Trigonia zlambachiensis O. Haas, 1909 † accepted as Protrigonia zlambachiensis (O. Haas, 1909) †
Species Trigonia zmurkensis Mordvilko, 1956 †
Species Trigonia zonata Agassiz, 1840 †
Species Trigonia zulu Strand, 1928 †
Species Trigonia zwingeri Agassiz, 1840 †
Genus Geratrigonia T. Kobayashi, 1954 † (4)
Genus Guineana Skwarko, 1967 † (1)
Genus Heslingtonia C. A. Fleming, 1987 † (1)
Genus Kyushutrigonia Tamura & Nishimura, 1994 † (1)
Genus Latitrigonia T. Kobayashi, 1957 † (8)
Genus Nipponitrigonia L. R. Cox, 1952 † (7)
Genus Praemyophoria Khalfin, 1940 †
Genus Psilotrigonia L. R. Cox, 1952 † (5)
Genus Savelievitrigonia Repman, 1979 †
Superfamily Trigonioidoidea L. R. Cox, 1952 † (226)
Superfamily Trigonodoidea Modell, 1942 † (18)
Order Unionida (2 581)
Family Lyrodesmatidae P. Fischer, 1886 † (8)
Family Pseudarcidae Scarlato & Starobogatov, 1979 † (3)
Family Thoraliidae N. J. Morris, 1980 †
Superorder Heteroconchia incertae sedis † (1)
Infraclass Pteriomorphia (6 675)
Subclass Bivalvia incertae sedis (7)
Subclass Palaeotaxodonta accepted as Nuculida
Subclass Paleoheterodonta accepted as Palaeoheterodonta
Subclass Protobranchia (1 374)
Infraclass Cryptodonta † (342)
Class Caudofoveata (143)
Class Cephalopoda (1 917)
Class Conchifera accepted as Bivalvia
Class Cricoconarida † (1)
Class Gastropoda (102 988)
Class Lamellibranchiata accepted as Bivalvia
Class Loricata accepted as Polyplacophora
Class Mollusca incertae sedis † (372)
Class Monoplacophora (229)
Class Pelecypoda accepted as Bivalvia
Class Polyplacophora (1 381)
Class Polyplaxiphora accepted as Polyplacophora
Class Rostroconchia † (64)
Class Scaphopoda (753)
Class Solenoconchia accepted as Scaphopoda
Class Solenogastres (313)
Subclass Chaetodermomorpha accepted as Caudofoveata