Macha, Genus – synonym of Solecurtus, Genus
Macomangulus, Genus – synonym of Tellina, Genus
Macomopsis, Genus – synonym of Macoma, Genus
Macoploma, Genus – synonym of Macoma, Genus
Macrotoma, Genus – synonym of Macoma, Genus
Macrotritopus, Genus – synonym of Octopus, Genus
Mactrina, Genus – synonym of Goodallia, Genus
Maera, Genus – synonym of Tellina, Genus
Magdala, Genus – synonym of Lyonsia, Genus
Magniturbonilla, Genus – synonym of Turbonilla, Genus
Magulus, Genus – synonym of Gibbula, Genus
Maka, Genus – synonym of Solecurtus, Genus
Malleolus, Genus – synonym of Teredora, Genus
Mamillocylichna, Genus – synonym of Cylichna, Genus
Mamilloretusa, Genus – synonym of Retusa, Genus
Mangilia, Genus – synonym of Mangelia, Genus
Mangiliella, Genus – synonym of Mangelia, Genus
Manobittium, Genus – synonym of Bittium, Genus
Manotrochus, Genus – synonym of Jujubinus, Genus
Mantellum, Genus – synonym of Limaria, Genus
Manupecten, Genus – synonym of Chlamys, Genus
Maoricrypta, Genus – synonym of Crepidula, Genus
Maoritellina, Genus – synonym of Tellina, Genus
Margarita, Genus – synonym of Margarites, Genus
Marsenia, Genus – synonym of Lamellaria, Genus
Marteliella, Genus – synonym of Aclis, Genus
Martinea, Genus – synonym of Scrobicularia, Genus
Massotia, Genus – synonym of Alvania, Genus
Massotiella, Genus – synonym of Alvania, Genus
Matharena, Genus – synonym of Favorinus, Genus
Megastomia, Genus – synonym of Odostomia, Genus
Melampidae, Familia – synonym of Ellobiidae, Familia
Melanellidae, Familia – synonym of Eulimidae, Familia
Mendicula, Genus – synonym of Thyasira, Genus
Menippe, Genus – synonym of Aclis, Genus
Mesocybota, Genus – synonym of Arca, Genus
Metaplysia, Genus – synonym of Aplysia, Genus
Metaxylophaga, Genus – synonym of Xylophaga, Genus
Microcucullaea, Genus – synonym of Bathyarca, Genus
Microgloma, Genus – synonym of Phaseolus, Genus
Microlophus, Genus – synonym of Tritonia, Genus
Middendorffia, Genus – synonym of Lepidochitona, Genus
Miohinia, Genus – synonym of Nassarius, Genus
Miranda, Genus – synonym of Ancula, Genus
Mirua, Genus – synonym of Nassarius, Genus
Mirulinus, Genus – synonym of Jujubinus, Genus
Mitella, Genus – synonym of Calyptraea, Genus
Mitrula, Genus – synonym of Calyptraea, Genus
Modiolacea, Genus – synonym of Musculus, Genus
Modiolaria, Genus – synonym of Musculus, Genus
Moera, Genus – synonym of Tellina, Genus
Moerella, Genus – synonym of Tellina, Genus
Monia, Genus – synonym of Pododesmus, Genus
Moniziella, Genus – synonym of Alvania, Genus
Monodonta, Genus – synonym of Osilinus, Genus
Monoeciostrea, Genus – synonym of Ostrea, Genus
Monostichoglossa, Ordo – synonym of Sacoglossa, Ordo
Montaguia, Genus – synonym of Montacuta, Genus
Mopaliella, Genus – synonym of Lepidochitona, Genus
Mopaliopsis, Genus – synonym of Lepidochitona, Genus
Moschites, Genus – synonym of Eledone, Genus
Multidentata, Genus – synonym of Ovatella, Genus
Murchisonia, Genus – synonym of Turritella, Genus
Musculus, Genus – synonym of Tellina, Genus
Mutilastra, Genus – synonym of Osilinus, Genus
Mutiturboella, Genus – synonym of Pusillina, Genus
Myatella, Genus – synonym of Lyonsia, Genus
Myochlamys, Genus – synonym of Chlamys, Genus
Myoparo, Genus – synonym of Crenella, Genus
Myosotella, Genus – synonym of Ovatella, Genus
Myridas, Genus – synonym of Idas, Genus
Myrina, Genus – synonym of Idas, Genus
Myrinopsis, Genus – synonym of Idas, Genus
Myrsus, Genus – synonym of Venerupis, Genus
Mysia, Genus – synonym of Diplodonta, Genus
Mythus, Genus – synonym of Mytilus, Genus
Mytilarius, Genus – synonym of Mytilus, Genus
Mytlias, Genus – synonym of Mytilus, Genus
Myxia, Genus – synonym of Mysia, Genus