1. The structure of the ommatidia of the eye ofCalliphora erythrocephala is very similar to that ofDrosophila. 2. Primary and secondary pigment cells are present, but the basal pigment cells described by Lowne could not be identified, and probably dense groups of granules in the basal expansions of the secondary pigment cells were mistaken for separate cells. 3. At 24° C. the onset of pigment formation in eyes during pupal life is at about 72 hr.; and the sequence is yellow, brown and red, but the late phase deposition of pigment, and the appearance of red granules, does not occur until a few hours before emergence, which at 24° C. is at 240 hr. after puparia formation. 4. The white-eyed mutant ofCalliphora erythrocephala, which is sex-limited and appears only in the female, has eyes normal in structure, and with the full complement of both primary and secondary pigment cells, but there is complete suppression of the formation of all pigment granules.