Auliscus ovalis from Oamaru, New Zealand. Not, as per the slide label, Cerataulus polymorphus forma. minor. Single example on the slide, tilted away from the coverslip towards the bottom of the image. Prepared by Frederick Marshall. 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. 64 images stacked in Zerene (Pmax).
Auliscus ovalis Arnott 1861. Published in: Pritchard, A. (1861). A history of infusoria, including the Desmidiaceae and Diatomaceae, British and foreign. Fourth edition enlarged and revised by J. T. Arlidge, M.B., B.A. Lond.; W. Archer, Esq.; J. Ralfs, M.R.C.S.L.; W. C. Williamson, Esq., F.R.S., and the author. pp. [1]-xii, [1]-968, 40 pls [I-XV]. London: Whittaker and Co.. Page 846. See also Schmidt’s Atlas Plate 149, Figure 4, where it is referred to as Auliscus ellipticus. Schmidt describes this as ‘related’ to A. ovalis Arnott.
For comparison see – https://diatomimaging.com/auliscus-ovalis-samuel-henry-meakin/