A strew slide of diatoms from Bridlington beach, Yorkshire, UK. Fresh water diatoms. There is a river which empties into the harbour (called Gypsey Race), so these could be from there. Material provided by Colin Lamb. Slide was prepared by Horace Dall. Dated 1983, shadowed with aluminium in a vacuum. Standard brightfield illumination gives a darkground image with full NA even for a high NA objective. Olympus BHB microscope using 365nm LED light (450nm for the 10x image image). As well as the wider field of view image, I photographed a couple of individual diatoms using 365nm light. 63x Leitz Pl Apo 1.4, oil immersion. Olympus Abbe condenser, oil immersion, brightfield lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Images stacked in Zerene (Pmax) for the view of the valve face, but a single unstacked image for the girdle view. I am fairly sure these are Fragilaria sp..