234 BIRD LIFE 



surface of this coat is either smooth and polished as in 

 Nectarinia' (the Sunbirds), 'or exhibits very fine 

 longitudinal wavy ridges when the feather is violet, or 

 numerous small dot-like irregularities as in Galbula' 

 (bright-coloured South American birds which, to the 

 eye of the uninitiated, look many of them not unlike 

 Kingfishers). ' The coating seems to act like a number 

 of prisms. All metallic feathers appear black when 

 their surface is parallel to the rays of the light in the 

 same level with the eye and the light. To the eye of 

 the observer the metallic collar of Ptilorhis magnified ' 

 (the Rifleman Bird of Paradise) will in one position 

 ' appear absolutely black,' in others ' bright coppery 

 red ' or ' rich green ; the metallic feathers of the sides 

 of the breast in the same bird will change' with the 

 position from which it is seen, ' from black to green and 

 to blue. The beautiful "Pharomacrus moccino' (the 

 Trogon which Montezuma in the days of Cortez kept as 

 a royal bird, and with a staff of attendants to wait upon 

 it, and which is now the national emblem of Guatemala, 

 as is the Eagle of a more northerly American Republic) 

 ' changes from greenish bronze through golden green, 

 green, and indigo to violet. Oreotrochilus chimborazo ' 

 (one of the Humming-birds) ' exhibits the whole solar 

 spectrum, namely, violet and red on the head, followed 

 by orange and green on the back, blue, violet, and 

 lastly purple on the long tail feathers.' 



When we remember that every feather thus mar- 

 vellously built and decorated is changed, probably, 

 at least once a year, the marvel is not lessened. 



