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Description of PsammonobiotidaeTest more or less shaped like a Greek vase, with funnel-shaped or disk-like apertural collar; aperture may be terminal or more or less bent to one side; clear or with attached or embedded particles. The concept of the Family applied here differs from that of Golemansky (1974) in that genera with round or oval siliceous idiosomes are excluded and placed with the Euglyphida; those with terminal collar like Micramphora, Nadinella and Ogdeniella are included. Whether these genera form a natural group is open to dispute. The striking similarity of the apertural structures is perhaps only a convergence as a result of the selective pressure in the interstitial environment. The genera of this family are separated mainly by characters of the shell. None of the species has been established in clonal culture, a critical evaluation of the diagnostic characters is lacking. The distinctions between the genera have been partly lost by recent species descriptions - and this also may make identification to genus difficult.