Triceratium sp. from St Laurent la Vernède, France. Single example on the slide. Dated 18/11/1944 and mounted in Styrax. No makers name but based on style and handwriting I think this is by WF Reeve. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 54 images stacked in Zerene.
Ok, the name. I looked through what literature I had on St Laurent and could find an obvious match. To me it looks like a group of diatoms which are often called Sheshukovia so I looked through a couple of articles on those. It looks a bit like Triceratium flos (also known as Sheshukovia flos). The overall shape looks similar, but the size of the holes on the apices looks wrong (for example see here). The ones here are much more coarse in size. I only found one example of ‘Triceratium flos‘ from St Laurent online and it does look like the one here, but doesn’t give any references. So for now I will leave it with a very tentative ID of Triceratium flos.