INTRODUCTION. Xix 



the lung. In certain species pf Geese it forms a coil be- 

 tween the skin and breast muscles; and in a large num- 

 ber of the Ducks and Mergansers, several lower rings of 

 the trachea are united together and enlarged, producing 

 a capsule in the throat. These convoluted windpipes in- 

 crease the volume of the voice, as in the case of the 

 Trumpeter Swan, and in numbers of other Fannlies the 

 twisting 'and winding of this organ are carried to an ex- 

 treme within the breast bone, as is seen in the \\'iiooping 

 Crane (Cms amcricaiia) and other species. 



The wings vary in shape and in comparative length to 

 the body. Some species have these very short, and 

 they are moved with great rapidity, sometimes appear- 

 ing devoid of outline' so swift is their action, and their 

 possessors go buzzing through the air more like insects 

 than birds. Again the wings are long and pointed, and 

 when the bird is flying are moved more slowly. Most of 

 the Anatidas, however, are rapid flyers, and even large 

 species like Swan and Geese, although their flight may 

 appear labored, proceed with much speed. 



The plumage is dense and consists of a coating of 

 down next to the skin, protected by the overlapping outer 

 feathers, affording a very warm covering. Most of the 

 species have a subdued coloring, but some are arrayed 

 in a gorgeous dress of many hues, frequently exhibiting 

 the brilliancy of metallic iridescence. The tail is of va- 

 rious shapes, rounded, cuneate, or with the median pair 

 of feathers moderately or greatly elongated. The bills 

 also vary greatly, from those that are broad, low, and flat, 

 through a shape short, high at base, and rather pointed at 

 tip, to one long, narrow, hooked, and serrated. The bill is 

 covered by a skin, which in the Swan extends to the eye, 

 leaving the lores bare. The sternum or breast bone 

 being broad and flat with little or no keel, the pectoral 



