Two arrangements of Auliscus elegans, 3 from Redondo beach deposit, and 5 from Patos Island guano. Redondo beach is in California, USA. The Patos Island guano is presumably Patos Island (also known as Isla de Patos or “Duck Island”) in the Gulf of California (Mexico) which is historically recognized as one of the “guano islands” in the Midriff region. Mounted in liquid ambar. No makers name. Olympus BHB microscope using 450nm LED light. As well as the arrangement, I imaged the largest from the Redondo group, and the Patos Island guano group using the 63x Leitz Pl Apo NA 1.4 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Image stacks prepared in Zerene (Pmax), 59 images for the Redondo one, and 63 images for the Patos Island one.
Aulacodiscus elegans Grove & Sturt, 1887. Original description: Grove, E. & Sturt, G. (1887). On a fossil marine diatomaceous deposit from Oamaru, Otago, New Zealand. Appendix. Journal of the Quekett Microscopical Club, Series 2, 3(19): 131-148, pls 10-14. Pages 140, 146, Plate 12, Figure 30. There is also another description of A. elegans. Auliscus elegans Greville 1863. Published in: Greville, R.K. (1863). A monograph of the genus Auliscus. Transactions of the Microscopical Society, New Series, London 11: 36-53, pls II, III. Page 45, Plate 2[II], Figure 8.
Quite a beautiful and striking species and an impressive arrangement. I’m not sure on the maker for this slide, but I have just imaged a few of them by the same maker, and they are all interesting slides. If you want to see others by this maker search for BBBBB in the search function.
EDIT – based on the handwriting and style, and some conversations with experts, I this could be by Edmund Grove (of Grove and Sturt). But I have no 100% proof of this at the moment.