ANATID^. 



their appearance towards the end of July or the beginning 

 of August, becoming much more uniform in their general 

 colour, losing some of the most conspicuous external dif- 

 ferences which distinguish males from females, and which 

 are to be considered as secondary sexual characters. 



The female Wigeon has the bill bluish-black ; the irides 

 brown; head and neck brown tinged with rufous, and 

 speckled with dark brown ; the back varied with two 

 shades of brown, that in the centre of each feather the 

 darkest in colour, the paler brown on the margins tinged 

 with rufous ; quill and tail-feathers as in the male ; under 

 surface of the body nearly white. 



The young male birds of the year are, for a time, in 

 plumage resembling that of the females. 



The tube of the windpipe in the adult male Wigeon is 

 about six inches in length, and nearly equal in diameter 

 throughout; the form of the bony enlargement and the 

 depending bronchial tubes as figured in the vignette below. 



