Class Bivalvia Linnaeus, 1758 - bivalves Subclass Autobranchia Grobben, 1894 Superorder Heteroconchia Gray, 1854 Clade Heterodonta Neumayr, 1884 Superfamily Hiatelloidea Gray, 1824 [monotypic] 1 Family Hiatellidae Gray, 1824 - geoducks