PLATE 17 



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The longer left wing-coverts of adolescent (second plumage) male, adult male, and adult female 

 crested pigeons. X 0.9. Toda del., Apr. 1906. For comparison, feather by feather, in the 

 three forms. Depth of pigment and extent of iridescence indicated as in pi. 16. The blue 

 color gives the angles formed by the proximal border of the band-elements and the spots with 

 the feather shaft (see text). 





