RED-BREASTED MERGANSER. 



83 



The windpipe of the male of this speeies is very curious, and 

 differs something from that of the Goosander. About two inches 

 from the mouth it swells out to four times its common diameter^ 

 continuing of that size for about an inch and a half. This swell- 

 ing is capable of being shortened or extended ; it then continues of 

 its first diameter for two inches or more, when it becomes flattish, 

 and almost transparent for other two inches ; it then swells into a 

 bony labyrinth of more than two inches in length by one and a 

 half in width, over the hollow sides of which is spread a yellowish 

 skin like parchment. The left side of this, fronting the back of 

 the bird, is a hard bone. The divarications come out very regu- 

 larly from this at the lower end, and enter the lungs. 



The intention of Nature in this extraordinary structure is 

 probably to enable the bird to take down a supply of air to sup- 

 port respiration while diving ; yet why should the female, who 

 takes the same submarine excursions as the male, be entirely des- 

 titute of this apparatus ^ 



