An arrangement of three Actinoptychus packi from Panoche Hills, California. Cretaceous. Mounted in Hyrax. Prepared (or perhaps just sold) by Flatters and Garnett Ltd. Olympus BHB microscope using 450nm LED light. For the 20x objective image of the arrangement I left the background in the image. It makes me think they look like they are hewn from stone (which they were I suppose). I selected one, the upper middle one, for higher resolution imaging. 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. 52 images stacked in Zerene (Pmax).
Original description: Hanna, G. D. (1927). Cretaceous diatoms from California. Occasional Papers of the California Academy of Sciences. 13: 5-49 [including 5 plates]. Page 12, Plate 1, Figs 1-3.