An arrangement of four Actinoptychus diatoms from St Laurent, France. Labelled as Actinoptychus bifrons, but I am not convinced they are all that. Fossil marine material. Mounted in Naphrax and dated November 1966. Prepared by ECP Bone. Olympus BHB microscope using 450nm LED light. I imaged the largest one (which I think is A. bifrons) with a 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 d850 camera. 52 images stacked in Zerene (Pmax).
Actinoptychus bifrons A.W.F.Schmidt 1886. Published in: Schmidt, A.[W.F.] (1886). Atlas der Diatomaceen-kunde Series III: Heft 23. pp. pls 89-92. Aschersleben: Commissions-Verlag von Ludwig Siever’s Buchhandlung. Plate 90, Figure 6. Some of the others could be Actinoptychus stella or variants thereof (see for example other diatoms on Plate 90 of Schmidt’s Atlas).