Cocconeis sp?, top and bottom valves? from Commonwealth Bay. Rather rare. Prepared by SH Meakin. Mounted in Sirax, September 1943. Olympus BHB microscope using 450nm LED light. 63x Leitz Pl Apo NA 1.40 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, bright field lighting. 2.5x Nikon CF PL photoeyepiece, removed 11mm of tube spacer to increase field of view. Monochrome converted Nikon d850 camera. 17 images stacked in Zerene (Pmax). It seems as though Meakin had some questions about the species and whether these show the top and bottom of the diatom valves.
EDIT 12th February 2026. Yesterday I came across a paper which might shed a little light on these samples. The article is Romero, Oscar E.. “Morphological study of the genus Cocconeis Ehrenberg (Bacillariophyceae) collected during the 1897–1899 Belgian Antarctic Expedition” Botanica Marina, vol. 54, no. 2, 2011, pp. 179-188. https://doi.org/10.1515/bot.2011.020. In there are a couple of diatoms which look like these. The smaller one on the left looks like a valve of Cocconeis gautierii var. gautierii, while the larger one on the right looks to be Cocconeis japonica var. antarctica. I will however leave the label as is for now, as these are tentative assignments.