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Summary. Structural colours in birds are surveyed systematically. From this survey, the common structural configurations in feathers, producing bright colours of the iridescent and non‐iridescent types respectively, are seen to exclude one another Feather pigments of unusual shades or chemical constitutions have been included in the survey, since some of them produce colour effects similar to structural colours of the non‐iridescent type
L. Auber (Mon,) studied this question.