WING OF THE HOUSE-SPARROW. 75 



Thus the largest hen, although a bigger bird than the largest 

 cock, measures half an inch less in entire length of wing, this 

 difference being due entirely to the lengthening of the second to 

 the fifth primaries, with their coverts, in the male birds. These 

 same feathers are often, though by no means invariably, narrower 

 in the females than in the males, and when this is the case the 

 resisting power of the wing must be considerably weakened. 



The width of the wing from back to front shows little, if any, 

 sexual difference, the secondaries being about of equal length in 

 male and female ; the natural effect of breadth without corre- 

 spondingly developed length would be to produce a somewhat 

 heavier and slower flight, so that in every respect the male bird 

 has the advantage. 



