A slide with 6 examples of Epithemia turgida from Toome Bridge, County Antrim. Unknown maker, but it does have the intials W.M.M. Dated 1957. Olympus BHB microscope using 450nm LED light. 20x Nikon Plan Apo NA 0.65 objective. Olympus Aplanat Achromat condenser, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 16 images stacked in Zerene (Pmax). I like this arrangement, reminds me of a cross section through a camera lens, showing the elements (6e6g arrangement in this case).