Bukrylithus ambiguus Black, 1971a
In plan view under XPL, the wall, axial cross, and intercross segments show constant extinction, reflecting the orientation of their optic axes (c‑axes) perpendicular to the microscope stage. The stellate distal process, in contrast, exhibits white interference colours.
Loxolith with a single zeugoid wall, a fibrous axial cross bearing a stellate distal process, and a central area infilled by segments. The arms of the axial cross taper from the centre toward the wall. The axial cross supports a hollow, stellate distal process.
Bukrylithus is closely related to Vagalapilla, but differs in possessing a filled central area and a distal process with a distinct calyx.
Black, M. 1971a. Coccoliths of the Speeton Clay and Sutterby Marl. Proceedings of the Yorkshire Geological Society 38: 381-424.
Bukry, D. 1969. Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles 51 (Protista 2): 1-79.