Myida

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==