An arrangement of four Stictodiscus buryanus from Jérémie, Haiti. Unknown mounter. The mountant is described as ‘Liq. amb.’ which I presume is liquid amber (exudation of the American Sweetgum tree, liquidambar styraciflua, with a higher refractive index compared with Canada Balsam – RI 1.58 vs 1.53 for balsam – and I think another name for the mountant Styrax). Dated September 1922. It refers to Plate 131, Figure 3 of Schmidts Atlas der Diatomaceenkunde and it does match with the image in there. It is also mentioned in Greville, R.K. (1861). Descriptions of new and rare Diatoms. Series I. Transactions of the Microscopical Society, New Series 9: 39-45, pl. IV, Fig 1, relevant excerpts from which are provided here.
Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, brightfield lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 20 images stacked in Zerene (Pmax).