420 



SKELETONS OF BIRDS. 



these long spear-like processes exist, but without, as far as is known, 

 the lateral spurs. 



In many families of birds, as the ducks, (Anatidce,) the trachea or 

 windpipe of the male, affords valuable means of distinguishing between 

 the different natural groups, or even species, chiefly by the form of 

 the bony labyrinth, bulba ossea, situated at or just above the divarica- 

 tion of the bronchial tubes. A little trouble will enable the collector in 

 all cases to preserve this organ perfectly, as represented in the annexed 

 engraving, (Fig. 3:) Before proceeding to skin the specimen, a nar- 



Fig. 3. 



A 



B 



G\ 



u -'.. i 



Mergus serrator, $ . 

 Upper surface about one half natural size. 



