Triceratium dobreeanum var. novazealandica from Oamaru, New Zealand. Single example on the slide. There is no makers name on the label however it is very similar to slides by WA Firth, although Barbour brothers ones are also very similar. For now I’ve put it down as WA Firth but with a question mark. Dated 1886. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, brightfield lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 52 images stacked in Zerene (Pmax). Some minor damage to the coverslip, but not near the diatom.