Ukko, Genus – synonym of Beringius, Genus
Umbiculus, Genus – synonym of Gibbula, Genus
Unela, Genus – synonym of Microhedyle, Genus
Usatricolia, Genus – synonym of Tricolia, Genus
Utriculus, Genus – synonym of Retusa, Genus
Uzita, Genus – synonym of Nassarius, Genus