Gyrovalvulina columnatortilis (d'Orbigny in Guérin-Méneville, 1832)

Description:

Loeblich, A. R., Tappan, H. N., 1987: Foraminiferal genera and their classification.  Van Nostrand, Reinhold Co. New York 1728 pp. Plate 202, Figs. 1-5: M. Eocene (Lutetian), Grignon, Dept. Seine et Oise, France. 1, Side view of hypotype showing early triangular and triserial stage, later cuneate chambers and final arcuate chambers that nearly completely encircle the test, giving a pseudouniserial appearance, x 50; 2, apertural view showing arcuate valvular tooth and encircling final chamber, x 50; 3, 4, longitudinal section, entire section, x 35, and part enlarged to show canaliculate wall, x 100; 5, part of surface enlarged to show openings of canaliculi at the surface, x 500 (from Loeblich and Tappan, 1985).