Slide labelled as Triceratium kinkerianum from Carlovo, Russia. Single example on the slide. I’m not certain the label for this one is correct. Could actually be Triceratium synicum (Medlinia synica) rather than T. kinkerianum (Medlinia venustu var. venustu). T. kinkerianum has ‘large hyaline central area’ which this does not. Also some hints of spikes towards the apices (as seen with synica). For more information on this see – Patricia A. Sims (1998) THE EARLY HISTORY OF THE BIDDULPHIALES. I. THE GENUS MEDLINIA GEN. NOV., Diatom Research, 13:2, 337-374, DOI:10.1080/0269249X.1998.9705455. Olympus BHB microscope using 390nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 14 images stacked in Zerene (Pmax).