Phylum Mollusca Linnaeus, 1758 - molluscs Class Gastropoda Cuvier, 1795 - snails and slugs Subclass Divasibranchia Minichev & Starobogatov, 1975 Order Stylommatophora Schmidt, 1855 see Infraorder Stylommatophora Schmidt, 1855 (Helicid Sigmurethra) Superfamily Helicoidea Rafinesque, 1815 Family Helminthoglyptidae Pilsbry, 1939 Subfamily Xanthonychinae Strebel & Pfeffer, 1879 Genus Xanthonyx Crosse & Fischer, 1867