I slide simply labelled Triceriatum from Chalky Mount, Barbadoes [sic]. Single example on the slide, with some damage. I think this is Triceratium plicatum and more on this in a minute. Prepared by WA Firth. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 61 images stacked in Zerene (Pmax).
Back to the name. The slide just says Triceriatum, and after a bit of hunting around I came across Triceriatum plicatum in Schmidt’s Atlas (Plate 94, Figure 8) which was a good visual match. This is a translation of what Schmidt said about it;
Barbadoes [sic], Chalky Mount, (Weissfl.) Triceratium plicatum Grunow. The middle bands are in deeper focus; That is why the sculpture [structure] is not punctured, but is drawn in a meshy manner, as it appears when one precisely adjusts the higher parts of the bowl.
Location is correct (Chalky Mount). Schmidt is describing one with the rim facing upwards (i.e. bowl shaped). The one on this slide is the other way up with the rim facing away from the coverslip. On this slide, the ‘middle bands’ are closer to the coverslip, which would be in keeping with Schmidt describing them as being ‘in deeper focus’ on his, given the difference in orientation.
Overall, I’m fairly confident with this identification as Triceratium plicatum, from Chalky Mount, Barbados.