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 Architectonicoidea Gray, 1850 Family Mathildidae Dall, 1889 Genus Mathildona Iredale, 1929