SHOVELER. 



153 



degrees to tlie true distinctive plumage of the sex, but do 

 not attain it till after the old males have completed their 

 change under the influence of the autumn moult. 



The tube of the trachea in the Shoveler male is about 

 seven inches long, and nearly uniform in size throughout its 

 length, with a small hollow bony protuberance on the left 

 side, from which it will be observed by the figure below 

 that one bronchial tube goes off to the lobe of the lungs 

 on its own side ; the other bronchial tube comes off from 

 the right inferior portion of the bone of divarication at the 

 bottom of the trachea. 



The second figure below represents the lower part of the 

 trachea, and the bronchial tubes in the female Shoveler, in 

 which, as in all the other females of the Anatidse, there is 

 no bony enlargement. 





