A slide with an arrangement of three diatoms. The middle looks to be a Gomphonema sp., the two disc ones maybe Lindavia sp. Written on the slide label is “Gomphonema don’t know. Note: lack of puncta on raphe ends of centre [diatom]. Broken foot. ASA [Schmidt’s Atlas] 266/37.”. No makers name. 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. 28 images stacked in Zerene (Pmax).
The reference to Schmidt’s Atlas is Gomphonema continuum F.Fricke. Schmidt’s Atlas Plate 266, Figure 37, Gomphonema continuum from Demerara River (Guyana, South America).
As for the circular diatoms, maybe Lindavia balatonis (Pantocsek) Nakov, Guillory, Julius, Theriot & Alverson, 2015. Published in: Nakov, T., Guillory, W.X., Julius, M.L., Theriot, E.C. & Alverson, A.J. (2015). Towards a phylogenetic classification of species belonging to the diatom genus Cyclotella (Bacillariophyceae): Transfer of species formerly placed in Puncticulata, Handmannia, Pliocaenicus and Cyclotella to the genus Lindavia. Phytotaxa 217(3): 249-264. Page 254. Basionym: Cyclotella balatonis Pantocsek. However I am less certain about these.