368 ANATID^. 



twenty-two inches in length ; the wing ten inches and a 

 quarter. 



The Author has seen instances in which females of this 

 species have assumed to a considerable extent the appear- 

 ance of the plumage of the Drake, even to the curled feathers 

 of the tail. One of these birds was given to him when 

 alive by his friend Mr. John Morgan. In this female the 

 beak was yellowish-brown ; the head and upper part of the 

 neck a mixture of green and brown ; the white ring below 

 perfect ; the lower part of the neck and the breast chestnut- 

 brown ; the upper surface of the body a mixture of ash- 

 brown and dark brown ; the under surface dull white. 

 When this bird was examined after death the sexual organs 

 were found to be diseased, as in the cases of the Hen 

 Pheasants referred to and figured in the third volume, pages 

 102 and 103. In his ' Scandinavisk Fauna ' (pi. 163), 

 Nilsson has given a coloured figure of a Duck in this state 

 of plumage, which is called a barren female, and in which 

 the curled tail-feathers are very conspicuous. From the 

 general similarity in these females to the appearance 

 assumed for a time by healthy males in July, the Author 

 was disposed to refer the seasonal change in the males to 

 a temporarily exhausted state of the male generative organs, 

 and their consequent diminished constitutional influence on 

 the plumage. 



Varieties are not uncommon, but complete albino wild 

 birds are very rare. 



The windpipe of the Mallard is about ten inches long, 

 the diameter of the tube is of equal size throughout ; the 

 bony labyrinth is large, the vignette indicates the form by 

 its outline, but represents a section of the lower part of 

 the tube of the trachea, the bony cavity, and the bronchial 

 tubes, as seen from behind ; the enlargement in this, as 

 in most of the other species, being on the left side. The 

 object is to show the course of the air from each lobe of 

 the lungs to the single portion of the tube of the windpipe. 

 The column of air on the right side in the bird, and in the 

 representation, goes direct from the right lobe of the lungs 



