Family Cryptodifflugiidae Jung, 1942
Diagnosis: Surface organic or with attached mineral particles. Aperture terminal or eccentric.
Two genera with hyaline shells:
Genus Cryptodifflugia Penard, 1890
Shell smooth, clear, flask- or egg-shaped, circular in cross-section, with adhering foreign particles or smooth surface; nucleus vesicular; cyst in test, by mucous plug.
Genus Wailesella Deflandre, 1928
Shell brown, aperture eccentric. Shells superficially remember Trinema shells.
Genus Meisterfeldia Bobrov, 2016
Ovoid shell, which is bilaterally symmetrical and laterally compressed, composed of proteinaceous material without mineral particles; circular subterminal aperture placed on ventrally and obliquely cut apertural end, or it is situated on a well developed or poorly expressed neck inclined ventrally