A strew slide from Hakodate, Japan. This is fossil marine material. Mounted in Styraclor and dated May 1995. Prepared by Bernard Hartley. Olympus BHB microscope using 450nm LED light. As well as the strew, I imaged a couple of what I think are Coscinodiscus sp. (more on this in a minute) using 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 Nikon d850 camera. Images stacked in Zerene (Pmax).
Back to the name for the high resolution images. When looking at them, they looked familiar to me, but I couldn’t place where I had seen them before. They are quite common on this slide. After a bit of searching I came across an image of Coscinodiscus elegans, and I think this is probably the right name for these. Coscinodiscus elegans Greville 1866. Published in: Greville, R.K. (1866). Descriptions of new and rare Diatoms. Series XVIII. Transactions of the Microscopical Society, New Series, London 14: 1-9, pls I, II. Page 3, Plate 1, Figure 6. Algaebase has a Actinocyclus rattrayi D.M.Williams as a synonym of this, but I can see no evidence of the hole just inside the rim which is so typical of an Actinocyclus. I did also fine reference to C. elegans at Hakodate in CN Walter’s, A Diatomist’s Vade Mecum (http://www.microscopy-uk.org.uk/diatomist/cnwalter.pdf). Overall I am fairly confident of these being examples of C. elegans, but not very confident.