Cyclagelosphaera margerelii Noël, 1965
Circular placoliths have single-tiered distal and proximal shields and a double tube cycle. All except the outer tube cycle exhibit inclined extinction lines and length-fast (-) elongation. The extinction lines are dextrogyre on the distal side, and their typical angles are typically around 73° on the distal shield and 60° on the tube cycles on the distal side (Figures 21AB). In the plan view, the outer tube cycle remains in constant extinction because the optic is vertical relative to the microscope stage. The central area may be open without any structure or
Noël, D. 1965. Sur les Coccolithes du Jurassique Européen et d'Afrique du Nord. Essai de classification des coccolithes fossiles. Éditions du Centre National de la Recherche Scientifique, Paris. 1-129.