"Lower Heterobranchia" (basis of record)
Abbottellinae Watters, 2016 (status source)
Acanthinulinae Steenberg, 1917 accepted as Valloniidae E. S. Morse, 1864 (status source)
Achatinellidae Gulick, 1873 (basis of record)
Achatinellinae Gulick, 1873 (basis of record)
Achatinidae Swainson, 1840 (basis of record)
Achatinina (basis of record)
Achatinoidea Swainson, 1840 (basis of record)
Aclididae G. O. Sars, 1878 accepted as Eulimidae R. A. Philippi, 1853 (source of synonymy)
Acochlidiimorpha (basis of record)
Acochlidioidea Küthe, 1935 (basis of record)
Acteocinidae Dall, 1913 accepted as Tornatinidae P. Fischer, 1883 (source of synonymy)
Acteonellidae Gill, 1871 † (basis of record)
Acteonelloidea Gill, 1871 † (basis of record)
Acteonidae A. d'Orbigny, 1842 (basis of record)
Acteonimorpha (basis of record)
Actinocyclidae O'Donoghue, 1929 (basis of record)
Adelomelonini Pilsbry & Olsson, 1954 (basis of record)
Aegiridae P. Fischer, 1883 (basis of record)
Aegistini Kuroda & Habe, 1949 (basis of record)
Aegopinella Lindholm, 1927 (taxonomy source)
Aeolidioidea Gray, 1827 (basis of record)
Aillyidae H. B. Baker, 1955 (additional source)
Akeroidea Mazzarelli, 1891 (basis of record)
Amastridae Pilsbry, 1910 (basis of record)
Amastrinae Pilsbry, 1910 (basis of record)
Amathinidae Ponder, 1987 (basis of record)
Amberleya J. Morris & Lycett, 1851 † (subsequent type designation)
Amoriinae J. E. Gray, 1857 (basis of record)
Amoriini J. E. Gray, 1857 (basis of record)
Ampezzanildidae Bandel, 1994 † (basis of record)
Ampezzonaticopsinae Bandel, 2007 † (basis of record)
Ampezzopleura Bandel, 1991 † (subsequent type designation)
Ampezzopleurinae Nützel, 1998 † (basis of record)
Amphibulimidae P. Fischer, 1873 (basis of record)
Amphigastropoda † (taxonomy source)
Amphitomariidae Bandel, 1994 † (basis of record)
Ampullariidae J. E. Gray, 1824 (additional source)
Anabathridae Keen, 1971 (basis of record)
Anadenidae Pilsbry, 1948 (basis of record)
Andangulariinae Nützel & Erwin, 2004 † (basis of record)
Angariidae J. E. Gray, 1857 (basis of record)
Anomphalidae Wenz, 1938 † (basis of record)
Anoptychia Koken, 1892 † (status source)
Anoptychia supraplecta (Münster, 1841) † (status source)
Antonellini C. M. Cooke & Y. Kondo, 1961 (basis of record)
Aplysiida (basis of record)
Aplysioidea Lamarck, 1809 (basis of record)
Araeonematidae Nützel, 2012 † (basis of record)
Archaegopis Wenz, 1914 † (additional source)
Archaeogastropoda accepted as Vetigastropoda (status source)
Archaeophialidae Knight & Yochelson, 1958 † (basis of record)
Archaeozonitidae Pfeffer, 1930 † (additional source)
Architaenioglossa (additional source)
Architectonicidae J. E. Gray, 1850 (basis of record)
Architectonicoidea J. E. Gray, 1850 (basis of record)
Areneidae J. H. McLean, 2012 (basis of record)
Argnidae Hudec, 1965 (basis of record)
Ariolimacidae Pilsbry & Vanatta, 1898 (basis of record)
Arionidae Gray, 1840 (basis of record)
Arionoidei (basis of record)
Ariophantidae Godwin-Austen, 1883 (basis of record)
Arminoidea Iredale & O'Donoghue, 1923 (1841) (basis of record)
Asthelysinae B. A. Marshall, 1991 (basis of record)
Ataphridae Cossmann, 1915 † (status source)
Athletinae Pilsbry & Olsson, 1954 (basis of record)
Athoracophoroidea P. Fischer, 1883 (1860) (basis of record)
Atiliinae Cossmann, 1901 (basis of record)
Atlantidae Rang, 1829 (basis of record)
Auriculellinae Odhner, 1921 (basis of record)
Azecidae H. Watson, 1920 (basis of record)
Babyloniidae Kuroda, Habe & Oyama, 1971 (basis of record)
Baicaliinae P. Fischer, 1885 accepted as Baicaliidae P. Fischer, 1885 (basis of record)
Bathysciadiidae Dautzenberg & H. Fischer, 1900 (additional source)
Bellerophinidae Destombes, 1984 † (basis of record)
Bellerophontinae McCoy, 1852 † (basis of record)
Belomitridae Kantor, Puillandre, Rivasseau & Bouchet, 2012 (status source)
Beretrinae Bandel & Dockery, 2016 † (status source)
Binneyidae T. D. A. Cockerell, 1891 (basis of record)
Bostrycinae Breure, 2012 (basis of record)
Bothriembryontidae Iredale, 1937 (basis of record)
Bothriembryontinae Iredale, 1937 (basis of record)
Brachytrematidae Cossmann, 1906 † (basis of record)
Bradybaeninae Pilsbry, 1934 (1898) (basis of record)
Brochidiinae Yochelson, 1956 † (additional source)
Bucanopsinae Wahlman, 1992 † (taxonomy source)
Bucanospirinae Wenz, 1938 † (basis of record)
Buccinoidea Rafinesque, 1815 (additional source)
Bulimulidae Tryon, 1867 (basis of record)
Bulimulinae Tryon, 1867 (basis of record)
Bulinidae P. Fischer & Crosse, 1880 (basis of record)
Bullinidae Gray, 1850 accepted as Aplustridae Gray, 1847 (source of synonymy)
Bulloidea Gray, 1827 (basis of record)
Bunnyini H. Nordsieck, 1987 (basis of record)
Burnupiidae Albrecht, 2017 (original description)
Bursidae Thiele, 1925 (basis of record)
Busyconinae Wade, 1917 (1867) (status source)
Caecidae J. E. Gray, 1850 (basis of record)
Calliostomatidae Thiele, 1924 (1847) (basis of record)
Calliotectinae Pilsbry & Olsson, 1954 (basis of record)