Triceratium balaniferum from Sandai [Sendai], Japan. Single example on the slide. Prepared by Arthur Cottam. Olympus BHB microscope using 450nm LED light. 40x Leitz Pl Apo NA 1.00 objective, oil immersion. Olympus Aplanat Achromat condenser, oil immersion, oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. 72 images stacked in Zerene (Pmax).
Original description: Brun, J. & Tempère, J. (1889). Diatomées Fossiles du Japon. Espèces marines et nouvelles des calcaires argileux de Sendaï et de Yedo. Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 30(9): 75 pp., 9 pls. page(s): p. 59; pl. 6, fig. 4. Accepted Name: Entogoniopsis balanifera (J.Tempère & J.Brun) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams, 2015. There is some additional information on this in my page of a Sendai strew here.