CHAPTER XVI.

BIRDS--_concluded_.

The immature plumage in relation to the character of the plumage in both sexes when adult--Six classes of cases--Sexual differences between the males of closely-allied or representative species--The female assuming the characters of the male--Plumage of the young in relation to the summer and winter plumage of the adults--On the increase of beauty in the Birds of the World--Protective colouring-- Conspicuously-coloured birds--Novelty appreciated-- Summary of the four chapters on birds 183-238