Phylum Mollusca Linnaeus, 1758 - molluscs Class Gastropoda Cuvier, 1795 - snails and slugs Subclass Opisthobranchia Milne-Edwards, 1848 - opisthobranchs see Order Opisthobranchia Milne-Edwards, 1848 Order Notaspidea Fischer, 1883 [monotypic] see Suborder Notaspidea Fischer, 1883 Superfamily Pleurobranchoidea Gray, 1827 Family Pleurobranchidae Gray, 1827 Genus Tomthompsonia Wägele & Hain, 1991