226 THE STORY OF THE BIRDS 



naturalists, but it is doubtless a very extra- 

 ordinary one. 



Although we find a considerable amount of 

 modification in the tails of birds, and especially 

 in the Humming-Bird group, there can be little 

 doubt that they are more for decorative pur- 

 poses than for musical ones. Amongst the 

 Humming-Birds the rectrices vary considerably 

 in shape ; but the modification of the wing is 

 more important from a musical point of view. 

 These feathers are moved rapidly, and can be 

 manipulated better than the tail for the pro- 

 duction of special sounds. We ought also to 

 state that the wings of Humming-Birds are 

 remarkably free from decorative colours, but on 

 the other hand the tail is famous for the many 

 glorious tints it displays, rivalling the rain- 

 bow in splendour. In this group the remiges 

 are modified to an astonishing degree. In the 

 genus Selasphorus the first primary is sharply 

 pointed or abruptly excised at the tip ; in 

 Lafresnaya and Aglaeactis it is very narrow, 

 and sometimes curved inwards, upwards, or 

 outwards, whilst in other genera the quills or 

 shafts of the primaries are exceptionally thick 

 or abnormally swollen, as in Campylopterus and 

 Sphenoproctus. Most of these modifications are 



