WILD DUCK. 



179 



and under tail-coverts pale brown, slightly varied witli darker 

 brown, which occupies a portion of the centre of each feather ; 

 legs and toes orange, the interdigital membranes darker. 



The females are smaller than males, and measure but 

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

 quarter ; the first and second quill-feathers very nearly equal. 



I have seen two instances in which females of this species 

 have assumed to a considerable extent the appearance of the 

 plumage of the Mallard, even to the curled feathers of the 

 tail. One of these birds, in my own collection, was given 

 me when alive by my kind and liberal friend John Morgan, 

 Esq. 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 Pheasant, mentioned in the second volume, 

 page 285. In the recently published Illustrations to his 

 Fauna of Scandinavia, M. Nilsson has given a coloured figure 

 of a Duck in this state of plumage, plate 163, which is called 

 a barren female, and in which the curled tail-feathers are 

 made very conspicuous. From the general similarity in these 

 females to the appearance assumed for a time by healthy 

 males in July, I am disposed to refer this seasonal change 

 in males to a temporary exhausted state of the male gene- 

 rative organs and their consequent diminished constitutional 

 influence on the plumage. 



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 



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