Cocconeis grevillei. Single example on the slide. This name is currently regarded as a synonym of Campyloneis grevillei (W.Smith) Grunow & Eulenstein. No makers name, but the handwriting would have this as being prepared by Frederick Marshall. 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. 25 images stacked in Zerene (Pmax).
The original frames for the stack were relatively low contrast, even with the oblique lighting, and some of the structures present at different depths on the diatom were lost as a result of the stacking process. This can be seen when looking at crops from two of the original frames, one from the top surface of the diatom and another from the bottom, which show different features. The images are not co-located, and have had their contrast boosted to show the features.