An arrangement of four Triceratium atlanticum. I can’t decipher the location. No makers name but based on the style and handwriting this was prepared by WH Darlaston. 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. 70 images stacked in Zerene (Pmax).
Triceratium atlanticum Castracane 1886. Published in: Castracane, [C.A.] F. (1886). Report on the Diatomaceae collected by H.M.S. Challenger during the years 1873-76. In: Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-76. Botany. Vol. II. (Murray, J. Eds), pp. [1]-178. Page 111, Plate XVII [17], Figure 3.
I’ll add my own perspective here. This does not look like a ‘Triceratium‘ to me, so perhaps this is one that needs a new look at the name. For example, a synonymized names is Amphitetras atlantica (Castracane) De Toni, 1894 (although this is uncertain/unassessed).