Nitzschia grandis. Single example on the slide. No makers name, but from the overall design, I think this is a slide by Edmund Wheeler. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 20 images stacked in Zerene (Pmax).