- macandrewi Iredale, 1926 = Sepia novaehollandiae (family Sepiidae)

- maccoyi Petterd, 1879 = Guraleus jacksonensis (family Conidae – Mangeliinae)

- maccoyi Pritchard & Gatliff, 1899 = Cancellaria purpuriformis (family Cancellariidae – Cancellariinae)

- maccoyi Tenison Woods, 1876 = Austrorissopsis maccoyi (family Aclididae)

- maccoyi Tenison Woods, 1878 = Pellasimnia maccoyi (family Ovulidae – Ovulinae)

- macilenta Iredale, 1926 = Sepia cultrata (family Sepiidae)

- macleayana Tenison Woods, 1877 = Conus rutilus (family Conidae – Coninae)

- macleayana Tenison Woods, 1877 = Turbonilla acicularis (family Pyramidellidae – Turbonillinae)

- macleayi Angas, 1864 = Spurilla macleayi (family Aeolidiidae)

- macphersonae Burn, 1962 = Phyllodesmium macphersonae (family Facelinidae – Favorininae)

- macphersonae Gabriel, 1956 = Mitromorpha macphersonae (family Conidae – Clathurellinae)

- macrocystialis Ashby, 1924 = Acanthochitona macrocystialis (family Acanthochitonidae – Acanthochitoninae)

- macrohista Voss, 1969 = Histioteuthis macrohista (family Histioteuthidae)

- mactroides Tate & May, 1900 = Cyamiomactra mactroides (family Cyamiidae)

- maculata Perry, 1811 = Notocypraea angustata (family Cypraeidae – Pustulariinae)

- maculata Quoy & Gaimard, 1832 = Pleurobranchaea maculata (family Pleurobranchidae – Pleurobranchaeinae)

- maculata Quoy & Gaimard, 1835 = Bostrycapulus pretzgeri (family Calyptraeidae)

- maculosa Hedley, 1903 = Aclophoropsis maculosa (family Triphoridae – Triphorinae)

- maculosa Hoyle, 1883 = Hapalochlaena maculosa (family Octopodidae – Octopodinae)

- maculosa Pease, 1871 = Pseudamycla dermestoidea (family Columbellidae – Atiliinae)

- maculosus A. Adams, 1853 = Clanculus limbatus (family Trochidae – Trochinae)

- maculosus Sowerby, 1833 = Conus anemone (family Conidae – Coninae)

- magellanicus retiolus Hedley, 1914 = Fusitriton magellanicus retiolus (family Ranellidae – Ranellinae)

- magna Gatliff & Gabriel, 1911 = Cingulina magna (family Pyramidellidae – Turbonillinae)

- magna Tate, 1891 = Diala suturalis (family Dialidae)

- malinoides Gabriel, 1961 = Alaginella malina (family Marginellidae – Marginellinae)

- malinoides Gabriel, 1961 = Alaginella malina (family Marginellidae – Marginellinae)

- mamilla May, 1915 = Melanella mamilla (family Eulimidae)

- mamillata Verco, 1909 = Obesula mamillata (family Triphoridae – Triphorinae)

- mammilla May, 1919 = Specula mammilla (family Cerithiopsidae – Cerithiopsinae)

- mammilla Sowerby, 1844 = Livonia mammilla (family Volutidae – Cymbiinae)

- mandarinus Duclos, 1831 = Penion mandarinus (family Buccinidae – Siphonaliinae)

- maoria Finlay, 1927 = Mitra badia (family Mitridae – Mitrinae)

- maorum Hutton, 1880 = Octopus maorum (family Octopodidae – Octopodinae)

- margaretae Burn, 1966 = Noumea haliclona (family Chromodorididae)

- margaritacea Lamarck, 1804 = Neotrigonia margaritacea (family Trigoniidae)

- margaritae Burn, 1974 = Ercolania margaritae (family Limapontiidae)

- margaritina Lamarck, 1818 = Merisca margaritina (family Tellinidae – Arcopagiinae)

- marginata Lamarck, 1811 = Amalda marginata (family Olividae – Ancillariinae)

- marginata Tenison Woods, 1879 = Eulima augur (family Eulimidae)

- mariae Powell, 1940 = Terebra tristis (family Terebridae – Terebrinae)

- mariae Tenison Woods, 1876 = Laevilitorina mariae (family Littorinidae – Laevilitorininae)

- mariae Tenison Woods, 1876 = Merisca margaritina (family Tellinidae – Arcopagiinae)

- mariae Tenison Woods, 1876 = Notochlamys hexactes (family Pectinidae – Chlamydinae)

- mariae Tenison Woods, 1876 = Turbonilla mariae (family Pyramidellidae – Turbonillinae)

- marmorata Basedow & Hedley, 1905 = Paradoris dubia (family Discodorididae)

- marmorata Bergh, 1904 = Alloiodoris marmorata (family Discodorididae)

- marmorata Tenison Woods, 1876 = Patelloida latistrigata (family Lottiidae – Patelloidinae)

- marmorea Odhner, 1917 = Seila crocea (family Cerithiopsidae – Seilinae)

- massyae Pfeffer, 1912 = Tetronychoteuthis massyae (family Pholidoteuthidae)

- matthewsi Iredale, 1910 = Plaxiphora matthewsi (family Mopaliidae)

- matthewsi Tate, 1889 = Mactra jacksonensis (family Mactridae – Mactrinae)

- matthewsianus Bednall, 1906 = Leptochiton matthewsianus (family Lepidopleuridae)

- maugeana Burn, 1960 = Melibe maugeana (family Tethydidae)

- maugeana Burn, 1962 = Dendrodoris maugeana (family Dendrodorididae)

- maugeana Hedley, 1915 = Dentimargo maugeana (family Marginellidae – Marginellinae)

- maugeansis Burn, 1958 = Onchidoris maugeansis (family Onchidorididae)

- maugeansis Burn, 1966 = Haminoea maugeansis (family Haminoeidae – Haminoeinae)

- maugeanus Iredale & May, 1916 = Sypharochiton pelliserpentis (family Chitonidae – Chitoninae)

- maugeri Wood, 1828 = Clanculus maugeri (family Trochidae – Trochinae)

- mauritiana Philippi, 1847 = Austrolittorina unifasciata (family Littorinidae – Littorininae)

- mawlei Iredale & Hull, 1926 = Plaxiphora albida (family Mopaliidae)

- mawlei Iredale & May, 1916 = Callistochiton mawlei (family Ischnochitonidae – Callistoplacinae)

- mawlei Iredale & May, 1916 = Ischnochiton mawlei (family Ischnochitonidae – Ischnochitoninae)

- mawsoni Cotton, 1945 = Semicassis pyrum (family Tonnidae – Phaliinae)

- maximus Tryon, 1881 = Penion maximus (family Buccinidae – Siphonaliinae)

- mayana Hedley, 1922 = Paramontana mayana (family Conidae – Mangeliinae)

- mayana Tate, 1899 = Munditia mayana (family Liotiidae – Liotiinae)

- mayi Ashby, 1919 = Callistochiton antiquus (family Ischnochitonidae – Callistoplacinae)

- mayi Beddome, 1897 = Notocypraea comptoni (family Cypraeidae – Pustulariinae)

- mayi Cotton, 1947 = Glycymeris mayi (family Glycymerididae)

- mayi Finlay, 1926 = Cocculinella mayi (family Cocculinellidae)

- mayi Gatliff & Gabriel, 1911 = Myrtea mayi (family Lucinidae)

- mayi Iredale, 1930 = Pronucula mayi (family Nuculidae)

- mayi Kershaw, 1955 = Ethminolia probabilis (family Trochidae – Umboniinae)

- mayi May, 1923 = Notoacmea mayi (family Lottiidae – Lottiinae)

- mayi Pilsbry, 1895 = Ischnochiton mayi (family Ischnochitonidae – Ischnochitoninae)

- mayi Tate, 1899 = Orbitestella mayi (family Orbitestellidae)

- mayi Tate, 1900 = Melanella mayi (family Eulimidae)

- mayi Torr, 1913 = Callochiton mayi (family Ischnochitonidae – Callochitoninae)

- mayii Tate, 1898 = Odostomia mayii (family Pyramidellidae – Odostomiinae)

- mayii Tate, 1900 = Dentimargo mayii (family Marginellidae – Marginellinae)

- medietas Burn, 1962 = Berthella medietas (family Pleurobranchidae – Pleurobranchinae)

- mediolaevis Cotton, 1944 = Pusillina mediolaevis (family Rissoidae – Rissoinae)

- megapicalis Ponder & de Keyzer, 1992 = Diala megapicalis (family Dialidae)

- megastoma Pilsbry, 1895 = Tricolia variabilis (family Phasianellidae – Tricoliinae)

- megastoma Ponder & Yoo, 1976 = Pisinna megastoma (family Anabathridae)

- melaleuca Quoy & Gaimard, 1833 = Vexillum australe (family Costellariidae)

- melancholicus Chun, 1906 = Sandalops melancholicus (family Cranchiidae)

- melanochroma Tate, 1899 = Eatoniella melanochroma (family Eatoniellidae)

- melanostoma Gmelin, 1791 = Bembicium melanostoma (family Littorinidae – Lacuninae)

- melanotragus E. A. Smith, 1884 = Nerita melanotragus (family Neritidae – Neritinae)

- melanura Tenison Woods, 1877 = Eatoniella melanochroma (family Eatoniellidae)

- mellila Iredale, 1924 = Asteracmea illibrata (family Lottiidae – Lottiinae)

- menda Iredale, 1924 = Puncturella demissa (family Fissurellidae – Emarginulinae)

- menda Iredale, 1924 = Puncturella kesteveni (family Fissurellidae – Emarginulinae)

- menkeana Reeve, 1857 = Gari modesta (family Psammobiidae)

- menkeana Reeve, 1859 = Mitrella menkeana (family Columbellidae – Atiliinae)

- menkeanus Philippi, 1847 = Brachidontes erosus (family Mytilidae)

- meracus Iredale, 1936 = Sirius badius (family Capulidae)

- merces Iredale, 1924 = Ellatrivia merces (family Triviidae)

- meredithiae Tenison Woods, 1875 = Guraleus pictus (family Conidae – Mangeliinae)

- meredithiae Tenison Woods, 1876 = Guraleus alucinans (family Conidae – Mangeliinae)

- meridiana Iredale & Hull, 1925 = Cryptoplax iredalei (family Cryptoplacidae)

- meridionalis Ashby, 1919 = Callistochiton antiquus (family Ischnochitonidae – Callistoplacinae)

- meridionalis Brazier, 1877 = Phytia myosotis (family Ellobiidae – Pedipedinae)

- meridionalis Hedley, 1903 = Propilidium tasmanicum (family Lepetidae – Propilidiinae)

- meridionalis Tate, 1887 = Pecten fumatus (family Pectinidae – Pectininae)

- mestayerae Iredale, 1915 = Colubraria mestayerae (family Colubrariidae)

- metcalfei Angas, 1877 = Alaginella ochracea (family Marginellidae – Marginellinae)

- metcalfei Pritchard & Gatliff, 1900 = Syrnola metcalfei (family Pyramidellidae – Syrnolinae)

- metella Hedley, 1917 = Barbatia metella (family Arcidae – Arcinae)

- metulifera Bergh, 1905 = Acanthodoris metulifera (family Onchidorididae)

- meyeri Philippi, 1848 = Astele armillatum (family Calliostomatidae – Calliostomatinae)

- micans A. Adams, 1850 = Pseudoliotia micans (family Tornidae – Vitrinellinae)

- micans Angas, 1878 = Pronucula pusilla (family Nuculidae)

- micans Tenison Woods, 1876 = Melanella tenisoni (family Eulimidae)

- michaeli Gosliner & Johnson, 1994 = Hallaxa michaeli (family Actinocyclidae)

- michaeli Tenison Woods, 1877 = Syrnola tincta (family Pyramidellidae – Syrnolinae)

- micra Finlay, 1924 = Rissoella micra (family Rissoellidae)

- micra Petterd, 1884 = Koloonella micra (family Pyramidellidae – Unplaced)

- micra Pritchard & Gatliff, 1900 = Odostomia micra (family Pyramidellidae – Odostomiinae)

- micra Tenison Woods, 1876 = Lissotesta micra (family Turbinidae – Skeneinae)

- micra Tenison Woods, 1878 = Truncatella scalarina (family Truncatellidae – Truncatellinae)

- microcosta May, 1920 = Pisinna kershawi (family Anabathridae)

- microscopica May, 1910 = Aclis microscopica (family Aclididae)

- microscopica May, 1911 = Balanetta microscopica (family Marginellidae – Marginellinae)

- microscopica May, 1915 = Nepotilla microscopica (family Conidae – Rhaphitominae)

- microstoma Quoy & Gaimard, 1833 = Polinices sordida (family Naticidae – Naticinae)

- micrum Verco, 1895 = Salaputium micrum (family Crassatellidae)

- mija Burn, 1967 = Okenia mija (family Goniodorididae)

- miliacea Hedley, 1902 = Ledella miliacea (family Nuculanidae – Ledellinae)

- milligani Iredale & May, 1916 = Ischnochiton versicolor (family Ischnochitonidae – Ischnochitoninae)

- miltostoma Tenison Woods, 1876 = Pseudamycla miltostoma (family Columbellidae – Atiliinae)

- mimica Sowerby, 1897 = Zenepos mimica (family Conidae – Rhaphitominae)

- mimicum Iredale, 1924 = Eunaticina umbilicata (family Naticidae – Naticinae)

- minima Petterd, 1884 = Cystiscus angasi (family Cystiscidae – Cystiscinae)

- minima Sowerby, 1887 = Microvoluta australis (family Volutomitridae)

- minima Tenison Woods, 1876 = Epicodakia consettiana (family Lucinidae)

- minima Tenison Woods, 1876 = Lodderena minima (family Turbinidae – Skeneinae)

- minimum Tenison Woods, 1878 = Tubercliopsis cessicus (family Cerithiopsidae – Cerithiopsinae)

- minimus Hutton, 1873 = Monophorus angasi (family Triphoridae – Triphorinae)

- minor Dunker, 1875 = Vulsella spongiarum (family Malleidae)

- minor Philippi, 1851 = Phasianotrochus irisodontes (family Trochidae – Trochinae)

- minor Tate & May, 1901 = Austroginella johnstoni (family Marginellidae – Marginellinae)

- minorum Iredale, 1936 = Epitonium minorum (family Epitoniidae)

- minusculum Iredale, 1924 = Eunaticina umbilicata (family Naticidae – Naticinae)

- minuta Tenison Woods, 1876 = Anachis interrupta (family Columbellidae – Atiliinae)

- minuta Tenison Woods, 1876 non Fleming, 1813 = Pronucula pusilla (family Nuculidae)

- minuta Tenison Woods, 1877 = Hydrococcus brazieri (family Hydrococcidae)

- minuta Tenison Woods, 1877 = Zenepos minuta (family Conidae – Rhaphitominae)

- minutissima Tenison Woods, 1878 = Fusceulima perexigua (family Eulimidae)

- minutissimus Tenison Woods, 1876 = Cystiscus minutissimus (family Cystiscidae – Cystiscinae)

- minutocrassa Ponder, 1965 = Eatoniella atropurpurea (family Eatoniellidae)

- minutula Tate & May, 1900 = Awanuia minutula (family Aclididae)

- miranda Berry, 1918 = Histioteuthis miranda (family Histioteuthidae)

- mitraeformis Lamarck, 1811 = Lyria mitraeformis (family Volutidae – Volutinae)

- mitralis A. Adams & Angas, 1863 = Guraleus mitralis (family Conidae – Mangeliinae)

- mitsuii Baba, 1938 = Diaphorodoris mitsuii (family Onchidorididae)

- mixta Petterd, 1884 = Hydroginella mixta (family Marginellidae – Marginellinae)

- mixta Reeve, 1855 = Lottia mixta (family Lottiidae – Lottiinae)

- mixta Tate, 1899 = Onoba australiae (family Rissoidae – Rissoinae)

- mobilis Hedley & May, 1908 = Nassarius mobilis (family Nassariidae – Nassariinae)

- modesta Deshayes, 1855 = Gari modesta (family Psammobiidae)

- modesta Sowerby, 1833 (non Carpenter, 1865) = Abranda modestina (family Tellinidae – Tellininae)

- modestina auct., non Tate, 1891 = Merisca margaritina (family Tellinidae – Arcopagiinae)

- modestina Tate, 1891 = Abranda modestina (family Tellinidae – Tellininae)

- modestus Reeve, 1852 = Pecten fumatus (family Pectinidae – Pectininae)

- molinae Lichtenstein, 1820 = Onychoteuthis banksii (family Onychoteuthidae)

- molleri Iredale, 1931 = Notocypraea angustata (family Cypraeidae – Pustulariinae)

- molleri Laseron, 1954 = Splendrillia woodsi (family Drillidae)

- mollis Sowerby, 1823 = Hinea brasiliana (family Planaxidae – Planaxinae)

- mollis Sowerby, 1823 = Hinea brasiliana (family Planaxidae – Planaxinae)

- molokaiensis Pilsbry, 1917 = Tricolia variabilis (family Phasianellidae – Tricoliinae)

- molorthus Hedley & May, 1908 = Ollaphon molorthus (family Muricidae – Trophoninae)

- monachus Crosse & Fischer, 1864 = Plesiotrochus monachus (family Plesiotrochidae)

- monile A. Adams, 1862 = Alaba monile (family Litiopidae)

- monile Kiener, 1840 = Epidirona quoyi (family Turridae – Crassispirinae)

- monile Rousseau, 1854 = Epidirona philipineri (family Turridae – Crassispirinae)

- moniliformis Hedley & Musson, 1891 = Koloonella moniliformis (family Pyramidellidae – Unplaced)

- montebelloensis Preston, 1914 = Phasianella variegata (family Phasianellidae – Phasianellinae)

- morchi Angas, 1871 = Plastiscala morchi (family Epitoniidae)

- morum Philippi, 1848 = Clanculus limbatus (family Trochidae – Trochinae)

- moslemica Hedley, 1912 = Amoria undulata (family Volutidae – Amoriinae)

- mucronatus Sowerby, 1866 = Hypermastus mucronatus (family Eulimidae)

- multiangularis Tate, 1887 = Dianadema multiangularis (family Clavagellidae)

- multicarinata Tenison Woods, 1877 = Clanculus plebejus (family Trochidae – Trochinae)

- multicarinatus Fishe, 1876 = Austrocochlea porcata (family Trochidae – Trochinae)

- multicostata Broderip, 1827 = Lyria mitraeformis (family Volutidae – Volutinae)

- multicostata May, 1910 = Retizafra multicostata (family Columbellidae – Atiliinae)

- multicostata May, 1911 = Mitromorpha multicostata (family Conidae – Clathurellinae)

- multicostata Sowerby, 1843 (non Geinitz, 1839) = Lima nimbifer (family Limidae)

- multidentata May, 1920 = Cystiscus halli (family Cystiscidae – Cystiscinae)

- multidigitalis Burn, 1957 = Crimora multidigitalis (family Polyceridae – Triophinae)

- multilirata May, 1915 = Onoba multilirata (family Rissoidae – Rissoinae)

- multilirata Sowerby, 1894 = Seilarex turritelliformis (family Triphoridae – Metaxiinae)

- multimaculosa Rudman, 1987 = Chromodoris multimaculosa (family Chromodorididae)

- multiplicata Tate & May, 1900 = Cystiscus alternans (family Cystiscidae – Cystiscinae)

- munieriana Crosse, 1864 = Nassarius nigellus (family Nassariidae – Nassariinae)

- munita Hedley, 1903 = Sabinella munita (family Eulimidae)

- muratensis Cotton, 1944 = Lucidestea muratensis (family Rissoidae – Rissoinae)

- murrayi E. A. Smith, 1891 = Limea murrayi (family Limidae)

- muscaria Lamarck, 1822 = Austroginella muscaria (family Marginellidae – Marginellinae)

- mustelina Angas, 1871 = Serrata mustelina (family Marginellidae – Marginellinae)

- mutabilis May, 1909 = Risellopsis mutabilis (family Littorinidae – Littorininae)

- myodoroides E. A. Smith, 1885 = Thracia myodoroides (family Thraciidae)

- myosotis Draparnaud, 1801 = Phytia myosotis (family Ellobiidae – Pedipedinae)