THE PRINCIPAL BIRD GROUPS 69 



and are certainly entitled to rank in separate 

 sub-orders. The Screamers (Palamedeae) can 

 scarcely be regarded as web-footed, for the 

 membranes between the long toes are rudi- 

 mentary. In this group the uncinate processes 

 to the ribs are wanting, a character not found 

 in any other existing birds. The bill is short 

 and stout, a horn or caruncle starts from the 

 forehead of one species, and the wings are 

 armed with two sharp spurs. Another curious 

 feature is the series of air cells between the 

 skin and the muscles, producing a crackling 

 sound when the body is pressed. These birds 

 swim well, and to some extent resemble the 

 Waterhens in their habits. The eggs are white, 

 and the young are clothed with down. The 

 Flamingoes (Phoenicopteri) are more Anserine 

 in their affinities, but some of these may be 

 due to analogy. They stand to some extent 

 midway between the Storks and the Geese. 

 Their most striking external features are the 

 long legs and long neck. We have already 

 dwelt upon the singular formation of the bill 

 in this group. The anterior toes are webbed. 

 These birds build conical nests of mud, and 

 lay but a single chalky-w^hite egg for a sitting. 

 The young are hatched covered with down. 



