454 Mr. YARRELL on a new Species of Wild Swan. 
Fig. 2. Upper surface of the sternum of an older bird, showing 
the loop of the trachea occupying one side of the ca- 
vity only. Part of the slender plate of bone being 
cut away. 
3. Upper surface of the sternum of an adult bird, the cavity 
| wholly occupied by the loop of the trachea. Part of 
. the plate of bone being also cut away. 
All the representations are one-fourth less than the na- 
tural size. 
