A strew slide from Cherryfield, Maine, USA. range of species present. No makers name, but this looks like it is a Northern Biological Supplies slide. Olympus BHB microscope using 450nm LED light. I selected what I am fairly sure is an example of Neidium tumescens (formerly known as Navicula (firma var.) tumescens and shown in Schmidt’s Atlas Plate 49, Figure 10) for further imaging. 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. 34 images stacked in Zerene (Pmax).
There’s a nice review of Cherryfield diatoms (with images) by Richard Carter here.