Heads and Necks 263 
The Laughing Thrush of the Himalaya Mountains 
has every feather upon its head lengthened and perma- 
nently erect, forming a soft, spreading halo. 
Fie. 205.—Hooded Merganser. (From a photograph provided by the American 
Museum of Natural History.) 
In almost every Family of birds we find certain spe- 
cies with long, well-developed crests. Among the ducks, 
the Hooded Merganser has a compressed, semicircular 
halo of delicate feathers, while the Mandarin Duck has 
a broad, many-coloured, erectile crown, which is con- 
