Slide labelled as Navicula (I think this is a Lyrella sp.) from Mejillones, Bolivia (I’m thinking this is now Chile). Single example on the slide. Cover slip 0.0035” (0.09mm) – thin coverslip. Dated February 1897. Prepared by William Allott Firth. Label on the rear of the slide says “1 valve, large well marked (but cannot all be seen at once).”. 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. 89 images stacked in Zerene (Pmax).
A very pretty diatom, but I am not sure as to the species at the moment.