An arrangement of four Nitzschia sp. (the slide says N. sigmoidea, but I think the one on the right hand side is different) from Cawthorne, Yorkshire, UK. No makers name, but based on the style, I think this is prepared by WH Darlaston. Olympus BHB microscope using 450nm LED light. As well as the arrangement, I selected two (the 3rd and 4th in the arrangement) for imaging at higher resolution using a 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. 29 images stacked in Zerene (Pmax).
Nitzschia sigmoidea (Nitzsch) W.Smith 1853. Published in: Smith, W. (1853). A synopsis of the British Diatomaceae; with remarks on their structure, function and distribution; and instructions for collecting and preserving specimens. The plates by Tuffen West. In two volumes. Vol. I. pp. [i]-xxxiii, 1-89, pls I-XXXI. London: John van Voorst, Paternoster Row. Page 38, Plate XIII [13], Figure 104.
The right hand one looks different to the others to me, which is more obvious in the 63x objective image. Maybe Nitzschia linearis?