Biddulphia rhombus, unknown mounter

Biddulphia rhombus slide, 20x Nikon Plan Apo NA 0.65 objective
Biddulphia rhombus var. trigona, underside facing upwards
Biddulphia rhombus var trigona, single image, 100x Leitz Pl Apo NA 1.32 objective, cropped
ImageJ analysis of the dot pattern, spacing 308nm
Biddulphia rhombus, top facing upwards

Biddulphia rhombus with 4 examples on the slide, from the seashore at Frieston, Lincolnshire, UK. Two Biddulphia rhombus and two Biddulphia rhombus var. trigona. For each species one example is present top side facing up towards the coverslip, and the other has the underside facing upwards. No name for the mounter. Olympus BHB microscope using 450nm LED light. Main stacks with a 100x Leitz Pl Apo NA 1.32-0.60 objective, oil immersion, set to wide open NA 1.32. Olympus Aplanat Achromat condenser, oil immersion, slightly oblique lighting. 2.5x Nikon CF PL photoeyepiece. Monochrome converted Nikon d850 camera. Stacked prepared in Zerene (Pmax). Some faint dot patterning which was more obvious on some of the single images rather than in the stacks. This had a spacing of about 308nm (measured in ImageJ).