Navicula crabro (now known as Diploneis crabro). Single example on the slide. Prepared by Watson and Sons Ltd. Mounted in Styrax and dated 18th May 1933. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo NA 1.40 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 33 images stacked in Zerene (Pmax).