Actinoptychus heliopelta from Dunkirk, Maryland. Single example on the slide. Prepared by Eric Impey. Mounted in Naphrax, dated October 1970. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo NA 1.4 Pl objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. Nikon CF 5x photoeyepiece. Removed 20mm of extension tube to fit the diatom in the field of view. Monochrome converted Nikon d800 camera. 27 images stacked in Zerene (Dmap).