Phylum Mollusca Linnaeus, 1758 - molluscs Class Bivalvia Linnaeus, 1758 - bivalves Subclass Palaeoheterodonta Newell, 1965 see Clade Palaeoheterodonta Newell, 1965 Order Trigonida orth. inval. [monotypic] 1 Superfamily Trigonoidea orth. inval. [monotypic] see Superfamily Trigonioidea Lamarck, 1819