Slide labelled as Navicula (I think this is probably Mastogloia lamprosticta, more on that in a minute) from Springfield, Barbados. Single example on the slide. Cover slip 0.0035” (0.09mm) – thin coverslip. Dated December 1893. Prepared by William Allott Firth. Label on the rear of the slide says “1 valve, large sparse dots. Serpentine median line – Interesting.”. 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. 44 images stacked in Zerene (Pmax).
Looking at various sources I think this is probably Mastogloia lamprostricta (W.Gregory) Brun 1896. Published in: Brun, J. (1896). Diatomées Miocènes, description des espèces. Le Diatomiste 2(24): 229-247, plates 19-24. Plate 22, Figure 8. Basionym: Cocconeis lamprosticta W.Gregory 1857. Published in: Gregory, W. (1857). On the post-Tertiary diatomaceous sand of Glenshira. Part II. Containing an account of a number of additional undescribed species. Transactions of the Microscopical Society of London 5: 67-88, pl. 1. Page 69, Plate 1, Figure 28 (as ‘Cocconeis (?) lamprosticta‘).
D&S have this spelt as ‘lamprosticta’ in their Oamaru Diatoms book, and I have also seen it spelt as ‘lamprostricta’. Presumably both the same, not sure as to the reason why there are two spellings.