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 Rissoelloidea Gray, 1850 Family Hyalogyrinidae Warén & Bouchet, 1993 [monotypic] 1 Genus Xenoskenea Warén & Gofas, 1993