Cryptodonta

The Cryptodonta are a nearly-extinct subclass of the bivalves. It contains a single extant order, Solemyida, while the Praecardiida are known only from fossils.

The valves of the shell are relatively thin and somewhat elongated. Unlike most other bivalves, species in this group have no hinge teeth on their shells. They have relatively primitive, "protobranchiate", gills.

Taxonomy

 * Cryptodonta
 * Order †Praecardiida
 * Family †Butovicellidae
 * Genus †Butovicella
 * Family †Praecardiidae
 * Genus †Slava
 * Genus †Cardiola
 * Family †Antipleuridae
 * Genus †Dualina
 * Genus †Hercynella
 * Genus †Panenka
 * Order Solemyida
 * Superfamily Solemyoidea
 * Family Solemyidae (awning clams)
 * Genus Acharax
 * Genus Solemya
 * Family Manzanellidae
 * Genus Manzanella
 * Genus Posterodonta
 * Family Nucinellidae
 * Genus Huxleyia
 * Genus Nucinella