Aulacodiscus excavatus. Location Singil (various spellings including Singeliewsky). Single example on the slide, underside facing the coverslip. Unknown maker. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 71 images stacked in Zerene (Pmax).
Slide says A.S. 36. 10. This corresponds to Schmidt’s Atlas, Plate 36, Figure 10.
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.