polar regions, grading to more weakly fluted near the center; wall thin, with thin tectum and slightly thicker finely alveolar diaphanotheca, single tunnel, weakly developed chomata in all but final two volutions, very heavy axial fillings occupying much of the polar regions of all but the last two whorls, coating the wall and partly filling the cham­bers. U. Permian (Murgabian); S. China; USSR: Pamir, Crimea.

 

Remarks: Although originally described as having a three-layered wall, Sheng (1963, *2896, p. 43, 168) stated that better preserved specimens show it to have only two layers.