An arrangement of Navicula firma. No location or makers name unfortunately. Olympus BHB microscope using 450nm LED light. I selected one (the larger one, just to the right of center in the arrangement) for imaging at higher resolution. 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. 22 images stacked in Zerene (Pmax), 13 images for the stack of the arrangement.
Navicula firma Kützing 1844. Published in: Kützing, F.T. (1844). Die Kieselschaligen Bacillarien oder Diatomeen. pp. [i-vii], [1]-152, pls 1-30. Nordhausen: zu finden bei W. Köhne. Page 92, Plate 21, Figure 10. This name is currently regarded as a synonym of Neidium firmum (Kützing) Pfitzer.