A slide labelled as “Pond Life, 50 forms circle slide”, and “Freshwater diatoms”. Prepared by Flatters and Garnett Ltd. This poor slide is not in good shape is highly degraded. Two diatoms selected for higher resolution imaging. Olympus BHB microscope using 450nm LED light. 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. Image stacks prepared in Zerene (Pmax), 22 images for the first one and 19 images for the second one. Both of these were either deeply set and/or the coverslip is thick as they were right at the limit of being imaged with this objective.
I’ve looked around for names, and have ended up at the following;
Neidium sp.. Maybe Neidium dilatatum or Neidium iridis?
Perhaps a Diatoma sp. or a Tetracyclus sp.. Less sure about this one. Maybe Diatoma vulgaris, Schmidt Atlas Plate 268, Figs 1-34 (spelt vulgare in Schmidt). This looks like a pretty good match. Also perhaps a Tetracyclus of some type. Tetracyclus ellipticus (Schmidt’s Atlas Plate 281), or Tetracyclus rhombus (maybe var. maxima) again look like potentials.