THE COLOURS OF BIRDS 



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bands near the tip of the general contour-feathers, or 

 as longitudinal bands at the edges of the quill-feathers. 



Fig. 2. — Barb and barbules from feathers of sun-birds, 

 magnified to show the peculiar structure of metallic barbules. 

 <z is a barb bearing both proximal and distal barbules, the 

 lower barbules being partially, the upper completely metallic. 

 h, non-metallic distal barbules from a tail-quill of a sun- 

 bird, showing lamina, booklets, and filamentous region. 

 c, partially metallic distal barbules ; the colour is confined 

 to the enlarged filamentous region, but the lamina and 

 booklets persist unaltered, d^ completely metallic barbules, 

 with no trace of booklets or lamina. 



In tint they are usually green, blue, violet, or reddish- 

 violet, yellow or red structural colours being absent. 



