An arrangement of Nitzschia sigmoidea from Cawthorne, Yorkshire, UK. No makers name, but based on the style this is by Herbert William Hutton Darlaston. Olympus BHB microscope using 450nm LED light. As well as the wider field of view I imaged one using the 63x Leitz Pl Apo NA 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting, parallel and perpendicular to the long axis. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Single unstacked images. Striae spacing 394nm (approx. 25.4 per 10µm).
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.