Two diatoms, Coscinodiscus and Cestodiscus sp. (with a question mark, from Cambridge, Barbados. Unknown maker. Olympus BHB microscope using 450nm LED light. For the Cestodiscus I used 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. 31 images stacked in Zerene (Pmax). It is an underside view with the rim towards the coverslip.
This could be Cestodiscus aff. intersectus. Written about in Strelnikova, N.I., Fourtanier, E., Kociolek, J.P. & Barron, J.A. (2001). Ultrastructure studies of Coscinodiscus and Cestodiscus species from the Eocene and Oligocene. In: Lange-Bertalot-Festschrift: Studies on Diatoms. It does look similar, and C. aff. intersectus is mentioned as being present but rare in the Bath Cliff, Barbados samples. C. aff. intersectus is also described in Brun, J. (1891). Diatomées espèces nouvelles marines, fossiles ou pélagiques. Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31(part 2, no.1): 1-47, pl. 11-22. page(s): p. 22; pl. 20, fig. 5 as Coscinodiscus (Cestodiscus) intersectus. However in this the ‘pearls’ (areolae) are described as bigger in the middle and then getting smaller towards the edges, which is not seen with this one. As such I am leaving it with a form question mark for now.
I recently acquired about 60 slides by this maker, so if you want to see others by them, search for AAAAA in the Search option at the top of the page, and I’ll include this in each of the pages for them.