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Test elongate, early stage triserial and triangular in section, later stage uniserial and rectilinear, with angular to rounded section; wall agglutinated, with considerable calcareous cement, in at least some species addition of a new chamber results in addition of an imperforate floor to the new chamber, so that the septa are secondarily doubled; wall canaliculate, fine canaliculi bifurcating within the wall, openings of the canaliculi sealed internally by an inner organic lining, and externally by the imperforate surface layer of the wall; aperture interiomarginal in the early triserial stage, terminal and rounded in the adult, with imperforate bordering rim and an imperforate apertural toothplate obstructing part of the aperture, reducing it to a semilunate form, then extending inward from the aperture through the chamber to attach to that preceding, successive toothplates oriented 120 degr. apart, reflecting the original triseriality. Paleocene to Holocene; cosmopolitan.