An Entogonia sp. from Springfield, Barbados. Single example on the slide. Prepared by Arthur Cottam. Olympus BHB microscope using 450nm LED light. 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. 54 images stacked in Zerene (Pmax) for the top view of the main part of the diatom. 12 images for the view of the structure underneath this main part of the diatom (I stacked this separately as when all done together it muddied the final view).
The slide originally said Entogonia marginata, but then this has been crossed out in pencil and changed to what looks to be Entogonia pulcherrima var. punctulata. I am therefore leaving this as just an Entogonia sp. at the moment, as I am not sure. There is a good review of this genus in: Holmes, R.W. & Brigger, A.L. (1979). The marine fossil diatom genus Entogonia Greville – A review. Bacillaria 2: 155-214.