1. Subgenus Trapezium (Schedotrapezium) Stewart, 1930 †
   1. Species Trapezium (Schedotrapezium) apolloniense Cox, 1952 †
   2. Species Trapezium (Schedotrapezium) carinatum Gabb, 1864 †
2. Species Trapezium bicarinatum (Schumacher, 1817)
3. Species Trapezium carteri (d'Archiac & Haime, 1854) †
4. Species Trapezium faba (d'Archiac & Haime, 1854) †
5. Species Trapezium gilvum (E. von Martens, 1872)
6. Species Trapezium oblongum (Linnaeus, 1758)
7. Species Trapezium sulcosum (O. Boettger, 1875) †
8. Species Trapezium tenue (O. Boettger, 1875) †
9. Species Trapezium transcarpaticum (Korobkov, 1951) †
10. Species Trapezium vicaryi (d'Archiac & Haime, 1854) †
11. Subgenus Trapezium (Neotrapezium) Habe, 1951 accepted as Neotrapezium Habe, 1951
    1. Species Trapezium (Neotrapezium) grignonense † accepted as Neotrapezium grignonense (Deshayes, 1824) † (unaccepted > superseded combination)
    2. Species Trapezium (Neotrapezium) infraeocaenicum (Gougerot, 1968) † accepted as Neotrapezium infraeocaenicum (Gougerot, 1968) † (unaccepted > superseded combination)
12. Subgenus Trapezium (Straelenotrapezium) Glibert & van de Poel, 1970 † accepted as Straelenotrapezium Glibert & van de Poel, 1970 † (unaccepted > superseded rank)
13. Subgenus Trapezium (Vanstraelenia) Glibert & van de Poel, 1966 † accepted as Trapezium (Straelenotrapezium) Glibert & van de Poel, 1970 † accepted as Straelenotrapezium Glibert & van de Poel, 1970 † (unaccepted > junior homonym, not Vanstraelenia Chabanaud, 1950 (Pisces); Straelenotrapezium is a replacement name)
14. Species Trapezium halioticola Dall, 1871 accepted as Milneria minima (Dall, 1871)
15. Species Trapezium japonicum Pilsbry, 1905 accepted as Neotrapezium liratum (Reeve, 1843)
16. Species Trapezium liratum (Reeve, 1843) accepted as Neotrapezium liratum (Reeve, 1843)
17. Species Trapezium nipponicum Yokoyama, 1922 accepted as Neotrapezium liratum (Reeve, 1843) (unaccepted > junior subjective synonym)
18. Species Trapezium obesa (Reeve, 1843) accepted as Glossocardia obesa (Reeve, 1843)
19. Species Trapezium perfectum Megerle von Mühlfeld, 1811 accepted as Trapezium oblongum (Linnaeus, 1758)
20. Species Trapezium rostrata [sic] accepted as Trapezium bicarinatum (Schumacher, 1817) (synonym; incorrect gender ending)
21. Species Trapezium rostratum (Lamarck, 1819) accepted as Trapezium bicarinatum (Schumacher, 1817)
22. Species Trapezium sowerbyi (Hidalgo, 1903) accepted as Trapezium gilvum (E. von Martens, 1872)
23. Species Trapezium sublaevigatum (Lamarck, 1819) accepted as Neotrapezium sublaevigatum (Lamarck, 1819)
24. Species Trapezium ventricosum Yokoyama, 1922 accepted as Neotrapezium liratum (Reeve, 1843) (unaccepted > junior subjective synonym)

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