Fig. 2. Light microscopical unstained sections of the same set of ommatidia at three different levels, 270 µm (A), 300 µm (B) and 320 µm (C). The existence of two ommatidial types is clear from the pigmentation. Four diagonally arranged pigment clusters occur distally in the round type (solid circles) and proximally in the trapezoidal type ommatidia (broken circles). In the transitional zone, some pigments exist in both types as in B. Note that the ommatidia of the trapezoidal type also bear orange pigment in the cell body (white arrowheads). Bar, 10 µm.