Ellipsagelosphaeraceae
Ellipsagelosphaera Christmas, 1965
Watznaueriaceae Rood et al., 1971
Circular to elliptical 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 in the plane view. The outer tube cycle shows constant extinction in the plane view because the optical axis is vertical relative to the microscope stage. The central area may or may not be occupied by structures.
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.
Rood, A. P., Hay, W. W. & Barnard, T. 1971. Electron Microscope Studies of Oxford Clay Coccoliths. Eclogae Geologicae Helvetiae. 64: 245-272.
