Phylum Mollusca Linnaeus, 1758 - molluscs Class Gastropoda Cuvier, 1795 - snails and slugs Subclass Heterobranchia Burmeister, 1837 [monotypic] see Superorder Heterobranchia Burmeister, 1837 Order Heterostropha Fischer, 1885 Superfamily Valvatoidea Gray, 1840 Family Orbitestellidae Iredale, 1917 Genus Orbitestella Iredale, 1917 Subgenus Omalogyrina Magne & Vergneau-Saubade, 1973