SIGMOILINA Schlumberger, 1887

 

 

Type species: Planispirina sigrnoidea Brady, 1884 (*344), p. 197; SD Cushman, 1917 (*708), p. 60.

Si_gmoilina Schlumberger, 1887 ( *2761), p. 118,Test ovate in outline, biconvex but asymmetrical. chambers one-half coil in length, at first added about 120° apart but the angle gradually increasing so that the chamber arrangement shows a sigmoid curve as seen in section. chambers with broad lateral extensions that overlap the earlier part of the test, resulting in a much thickened wall in the central area and a biloculine appearance from the exterior; wall calcareous, thick, imperforate. porcelaneous: aperture terminal, rounded, with a small tooth. Eocene?, L. Miocene (Burdigalian) to Holocene: cosmopolitan.