An arrangement of six Auliscus elegans from Patos Island, guano (Patos Island is apparently a small island in the San Juan Islands of the U.S. state of Washington). Prepared by Arthur Cottam. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 46 images stacked in Zerene (Pmax).
The main image is of the large one in the middle of the arrangement. Lots of really nice detail present. Using ImageJ the dot spacing was measured as being about 312nm.
The diatom is discussed in: Greville, R.K. (1863). A monograph of the genus Auliscus. Transactions of the Microscopical Society, New Series, London 11: 36-53, pls II, III.