• Aartsenia candida (Møller, 1842)
• Abavopsis latosoleata (Salvini-Plawen, 1973)
• Acera bullata (O. F. Müller, 1776) accepted as Akera bullata O. F. Müller, 1776
• Acera bullata var. nana Jeffreys, 1867 accepted as Akera bullata O. F. Müller, 1776
• Acera carnosa (Cuvier, 1810) accepted as Philinopsis depicta (Renier, 1807)
• Acera elegans Locard, 1886 accepted as Akera bullata O. F. Müller, 1776
• Acera marmorata Cantraine, 1841 accepted as Aglaja tricolorata Renier, 1807
• Aceras africana Locard, 1897 accepted as Cylichnium africanum (Locard, 1897)
• Aceras elegans Locard, 1886 accepted as Akera bullata O. F. Müller, 1776
• Aceras fischeri Locard, 1897 accepted as Cylichnium africanum (Locard, 1897)
• Actaeon minutum M. Sars, 1835 accepted as Elysia viridis (Montagu, 1804)
• Actaeonia corrugata Alder & Hancock, 1848 accepted as Limapontia senestra (Quatrefages, 1844)
• Actaeonia senestra Quatrefages, 1844 accepted as Limapontia senestra (Quatrefages, 1844)
• Acteocina crithodes (Melvill & Standen, 1901)
• Acteocina interrogens Gofas & Luque, 2021
• Acteocina mucronata (R. A. Philippi, 1849)
• Acteocina protracta (Dautzenberg, 1889)
• Aglaja berrieri (Dieuzeide, 1935)
• Aglaja depicta Renier, 1807 accepted as Philinopsis depicta (Renier, 1807)
• Aglaja maderensis (R. B. Watson, 1897) accepted as Melanochlamys maderensis (R. B. Watson, 1897)
• Aglaja minuta Pruvot-Fol, 1953
• Aglaja taila Ev. Marcus & Er. Marcus, 1966 accepted as Aglaja tricolorata Renier, 1807
• Aglaja tricolorata Renier, 1807
• Akera bullata O. F. Müller, 1776
• Akera flexilis T. Brown, 1844 accepted as Akera bullata O. F. Müller, 1776
• Akera silbo Ortea & Moro, 2009
• Akera striatella (Lamarck, 1804) †
• Alderella comosa (A. Costa, 1867)
• Alderia comosa A. Costa, 1867 accepted as Alderella comosa (A. Costa, 1867)
• Alderia modesta (Lovén, 1844)
• Alexia (Auricula) myosotis (Draparnaud, 1801) accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia (Auricula) myosotis var. hiriarti de Folin & Bérillon, 1874 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia (Kochia) oranica Pallary, 1900 accepted as Myosotella denticulata (Montagu, 1803) accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia (Leuconia) micheli (Mittre, 1841), sensu Bourguignat, 1864 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia (Leuconia) micheli var. elongata Pallary, 1900 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia (Leuconia) micheli var. incrassata Pallary, 1900 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia (Pseudomelampus) jolyi Pallary, 1900 accepted as Pseudomelampus exiguus (R. T. Lowe, 1832)
• Alexia (Pseudomelampus) kochi Pallary, 1900 accepted as Pseudomelampus exiguus (R. T. Lowe, 1832)
• Alexia algerica Bourguignat, 1864 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia armoricana Locard, 1891 accepted as Myosotella denticulata (Montagu, 1803) accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia balearica Dohrn & Heynemann, 1862 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia cossoni A. Letourneux & Bourguignat, 1887 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia enhalia Bourguignat, 1887 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia exilis Locard, 1893 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia kobelti Caruana-Gatto, 1890 accepted as Leucophytia bidentata (Montagu, 1808)
• Alexia letourneuxi Bourguignat, 1887 accepted as Myosotella denticulata (Montagu, 1803) accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia loweana L. Pfeiffer, 1866 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia micheli (Mittre, 1841), sensu Bourguignat, 1864 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia myosotis (Draparnaud, 1801) accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia myosotis var. varicosa Fenaux, 1939 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia obsoleta L. Pfeiffer, 1854 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia paivana L. Pfeiffer, 1866 accepted as Leucophytia bidentata (Montagu, 1808)
• Alexia parva Locard, 1893 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia pechaudi Bourguignat, 1887 accepted as Myosotella myosotis (Draparnaud, 1801)
• Alexia ringicula Locard, 1893 accepted as Myosotella denticulata (Montagu, 1803) accepted as Myosotella myosotis (Draparnaud, 1801)
• Aliculastrum cylindricum (Helbling, 1779)
• Amathina tricarinata (Linnaeus, 1767)
• Amaura candida Møller, 1842 accepted as Aartsenia candida (Møller, 1842)
• Amphisphyra expansa Jeffreys, 1865 accepted as Diaphana minuta T. Brown, 1827
• Amphisphyra flava R. B. Watson, 1897 accepted as Diaphana flava (R. B. Watson, 1897)
• Amphisphyra globosa Lovén, 1846 accepted as Diaphana globosa (Lovén, 1846)
• Amphisphyra hiemalis (Couthouy, 1839) accepted as Diaphana hiemalis (Couthouy, 1839)
• Amphisphyra hiemalis var. loveni Friele, 1886 accepted as Diaphana hiemalis (Couthouy, 1839)
• Amphisphyra ventricosa Jeffreys, 1865 accepted as Laona ventricosa (Jeffreys, 1865)
• Ancylus drouetianus Bourguignat, 1853 accepted as Williamia gussoni (O. G. Costa, 1829)
• Ancylus gibbosus (Bourguignat, 1862) accepted as Williamia gussoni (O. G. Costa, 1829)
• Ancylus gussoni O. G. Costa, 1829 accepted as Williamia gussoni (O. G. Costa, 1829)
• Anidolyta duebeni [sic] accepted as Anidolyta duebenii (Lovén, 1846) accepted as Tylodina duebenii Lovén, 1846
• Anidolyta duebenii (Lovén, 1846) accepted as Tylodina duebenii Lovén, 1846
• Anisocycla eulimoides Fekih, 1969 † accepted as Ebala eulimoides (Fekih, 1969) †
• Anisocycla macilenta (Monterosato, 1878) accepted as Bacteridium macilentum (Monterosato, 1878)
• Anisocycla pointeli (de Folin, 1868) accepted as Ebala pointeli (de Folin, 1868)
• Anisocycla pointeli planulata Gougerot & Feki, 1981 accepted as Ebala pointeli (de Folin, 1868)
• Antemnella loricata (Swedmark, 1968) accepted as Asperspina loricata (Swedmark, 1968)
• Aplysia (Pruvotaplysia) parvula Mörch, 1863 represented as Aplysia parvula Mörch, 1863
• Aplysia albopunctata Deshayes, 1853 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia allochroa Bergh, 1908 (uncertain > nomen dubium)
• Aplysia anguilla G. B. Sowerby I, 1869 (uncertain > taxon inquirendum)
• Aplysia atromarginata Bergh, 1905
• Aplysia australiana Clessin, 1899 accepted as Aplysia parvula Mörch, 1863
• Aplysia brasiliana Rang, 1828
• Aplysia brongniartii Blainville, 1825 (uncertain > nomen dubium)
• Aplysia brugnatelli van Beneden & Robb, 1835 accepted as Petalifera petalifera (Rang, 1828)
• Aplysia citrina Rang, 1828 accepted as Stylocheilus longicauda (Quoy & Gaimard, 1825)
• Aplysia concava G. B. Sowerby I, 1833
• Aplysia cuvieri Delle Chiaje, 1828 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia dactylomela Rang, 1828
• Aplysia depilans Gmelin, 1791
• Aplysia depressa Cantraine, 1835 accepted as Petalifera petalifera (Rang, 1828)
• Aplysia donca Ev. Marcus & Er. Marcus, 1960 accepted as Aplysia morio (A. E. Verrill, 1901)
• Aplysia dumortieri Cantraine, 1835 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia elongata (Pease, 1860)
• Aplysia fasciata Poiret, 1789
• Aplysia ferussaci Rang, 1828 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia gracilis Eales, 1960 accepted as Aplysia fasciata Poiret, 1789
• Aplysia griffithsiana Leach, 1852 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia guttata M. Sars, 1839 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia hybrida J. Sowerby, 1806 accepted as Aplysia punctata (Cuvier, 1803)
• Aplysia intermedia Farran, 1905 (uncertain > taxon inquirendum)
• Aplysia japonica G. B. Sowerby I, 1869