An arrangement of Actinocyclus oliveranus (spelt olivereanus on the slide) from Antarctic Ocean, 1900 fathoms, “Challenger” expedition. No makers name, but I understand this is by HRS Williams. No mountant details or date. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, brightfield lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 50 images stacked in Zerene (Pmax).
Initially when looking at this I was unsure about the Actinocyclus name for it, however in the 63x image, there is a small ‘hole’ near the rim at the 4 o’clock position which makes me less uncertain about it now.
Reference: O’Meara, E. (1876). On the Diatomaceous gatherings made at Kerguelen’s Land by H.N. Moseley M.A., H.M.S. Challenger. Journal of the Linnean Society, Botany, 15(82): 55-59, 1 pl. Shown in Plate 1, Figure 7.