Four diatoms on a slide labelled Eupodiscus velatus from Maryland, USA. All broken, but look to have broken in-situ on the slide. Mounted in Styrax and dated 3/11/[19]40. No makers name, but I think this is by WF Reeve (but will leave it with a question mark for now). Olympus BHB microscope using 450nm LED light. 20x Nikon Plan Apo 0.65 objective. Olympus Aplanat Achromat condenser, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 27 images stacked in Zerene (Pmax).
Eupodiscus velatus Greville ex Moller, 1868, 1881. Original description: Möller, J.D. (1868). Probe- und andere Platten. Wedel. Pages 4. 3. 12. Status: uncertain/unassessed.
Not to be confused with Eupodiscus vallatus Ba & Me.
I think these are probably Eupodiscus rogersii. Eupodiscus rogersii Ehrenberg, 1844. Published in: Ehrenberg, C.G. (1844). Mittheilung über 2 neue Lager von Gebirgsmassen aus Infusorien als Meeres-Absatz in Nord-Amerika und eine Vergleichung derselben mit den organischen Kreide-Gebilden in Europa und Afrik. Bericht über die zur Bekanntmachung Geeigneten Verhandlungen der Königl. Preuss. Akademie Der Wissenschaften zu Berlin 1844: 57-97. Page 81. This name is currently regarded as a synonym of Aulacodiscus rogersii (Ehrenberg) Schmidt 1886. Published in: Schmidt, A.[W.F.] (1886). Atlas der Diatomaceen-kunde. Series III: Heft 27/28. pp. pls 105-112. Aschersleben: Verlag von Ludwig Siever. Plate 107, Figure 3.