Myida (formerly Myoida) is an order of saltwater and freshwater clams, marine and freshwater bivalve molluscs in the subclass Heterodonta. The order includes such bivalves as soft-shell clams, geoducks and shipworms.
Description They are burrowing molluscs with well-developed siphons. The shell is relatively soft and lacks a nacreous layer. Some species have a single cardinal tooth.
Superfamilies and families Superfamilies and families within the Myida include (the use of † indicate taxa that are extinct):
Superfamily: Dreissenoidea Family: Dreissenidae Superfamily: Myoidea Family: Corbulidae Family: Myidae Family: †Pleurodesmatidae Family: †Raetomyidae Superfamily: Pholadoidea Family: Pholadidae Family: Teredinidae Family: Xylophagaidae Superfamily: †Pleuromyoidea Family: †Ceratomyidae Family: †Pleuromyidae Family: †Vacunellidae
References
Powell A W B, New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979
External links Animaldiversity Taxonomicon