A strew from the Challenger Expedition, 1872-1876. Station 149d, Royal Sound. Kerguelen Island (28 fathoms). Prepared by Bernard Hartley. Mounted in Styrax and dated October 1995. Range of diatom species present, along with sponge spicules and some sand grains. 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. Image stacks prepared in Zerene (Pmax). I selected a couple of regions to image further.
One is shown as the full image frame, along with everything that was in it. This includes what I think is a Psammodictyon sp. (perhaps Psammodictyon panduriforme) in the top middle of the frame, and a Hyalodiscus sp. in the bottom right.
The other is a cropped image showing a Cocconeis sp. I got a bit lucky with this as it was right by the coverslip ring, and I could still use the 63x objective. Looking through the usual sources, I came across a couple of possibilities for this one; Cocconeis jacksoni (from the ANSP website, very similar looking, but that one is a fossil). Cocconeis dehiscens (Schmidt’s Atlas Plate 197, Figs 5,6), which looks like a good match.
There is some really good information on Station 149d on the Microscopy UK website here.