Ocinebra, Genus – synonym of Ocenebra, Genus
Oda, Genus – synonym of Noemiamea, Genus
Odoncineta, Genus – synonym of Thracia, Genus
Odontidium, Genus – synonym of Caecum, Genus
Odontina, Genus – synonym of Caecum, Genus
Odontostoma, Genus – synonym of Odostomia, Genus
Odontostomia, Genus – synonym of Odostomia, Genus
Oicodespina, Genus – synonym of Onchidoris, Genus
Ommastrephes, Genus – synonym of Todarodes, Genus
Ommatostrephes, Genus – synonym of Todarodes, Genus
Orbiculus, Genus – synonym of Dosinia, Genus
Orbis, Genus – synonym of Acanthocardia, Genus
Orixa, Genus – synonym of Abra, Genus
Oronthea, Genus – synonym of Kellia, Genus
Ortygia, Genus – synonym of Chamelea, Genus
Oscaniella, Genus – synonym of Pleurobranchus, Genus
Oscanius, Genus – synonym of Pleurobranchus, Genus
Ossiania, Genus – synonym of Philine, Genus
Ostracarius, Genus – synonym of Ostrea, Genus
Oudardia, Genus – synonym of Tellina, Genus
Ozoena, Genus – synonym of Eledone, Genus