Figure 4. Visual unit, slightly, obliquely squeezed, of Chotecops ferdinandi Struve,1985, Age and location: Siegenian/Emsian Stage (~407 million years) lower Devonian, Bundenbach, Hunsrück, Germany.

(a) Obliquely ‘opened’ compound eye of B. cf. granulops. (b) schematic drawing of a. 1 lens, 2 ?lens-building cells 3 shielding pigment cells, 4 sensory cells, 5 efferent nerves of the sensory cells. Insert: Chotecops ferdinandi Struve,1985.