Loeblich, A. R., Tappan, H. N., 1987: Foraminiferal genera and their classification. Van Nostrand, Reinhold Co. New York 1728 pp. Plate 278, Figs. 1-4: U. Carboniferous (Stephanian), Virgil Series, Ervine Creek Shale Member, Deer Creek Limestone, Osage County, Oklahoma, USA. 1, 2, Axial section of lectotype, x 10, and part enlarged, x 20; 3, 4, sagittal sections, x 10 (1, 3, 4, from Thompson, 1948; 2, from Thompson, 1942). courtesy of Michael Hesemann https://foraminifera.eu