The Diplommatinidae are an extremely diverse family of land-living snails from the order of the Architaenioglossa ( Caenogastropoda ). All of them are small to very small species, only a few millimeters in size, which are included in the non-systematic group of “micromollusks”. The right- and left-wound, conical, egg-shaped-conical, sometimes irregularly rolled up and unrolled housings often have secondary deposits on the housing. Often the end turn is somewhat constricted. The housings usually have only a few turns. The mouth is usually rounded with or without folds or lamellas. The lid ( operculum ) is more or less calcified. The animals are of separate sex. The species and genera of the Diplommatidae are native to the tropics in Southeast Asia, Melanesia, Micronesia, Mexico, Central America and the Antilles. They occur from sea level up to 2600 m above sea level. The oldest members of the family come from the Upper Cretaceous of Hungary, but the genus Ajkaia can hardly be distinguished from the housings of other genera of the Diplommatinidae.