SWAN. NATATORES. CYGNUS. 283 



is necessary to be made, according to the supposed distance 

 of the object. When caught alive, it soon becomes very 

 tame, as seen in the instance mentioned by MONTAGU ; and 

 I have also, in several cases, known it survive for a long 

 time, and thrive well, when provided with plenty of water ; 

 it refuses, however, to associate with the common or mute 

 species. The food of the Swan consists of the roots, leaves, Foo<i ' 

 and stems of aquatic plants, in obtaining the former of which 

 its length of neck is of essential service, which it has also the 

 power of keeping submerged for a long time ; but as this is 

 done by the mute species perhaps in an equal degree, it can- 

 not be attributed to the peculiar form of the trachea, an idea 

 that has been suggested by different ornithologists. In the 

 present species, the elastic process or joint, in the upper man- 

 dible, which enables it to be opened to a considerable extent, 

 is very prominent, and more easily distinguished than in 

 many others of the Anatidae, in whom it is hidden by the 

 knob, or by the feathers of the brow. When swimming, the 

 neck is borne erect, at a right angle with the body, and sel- 

 dom arched, as is the custom of the Common Swan ; but in 

 walking (which is performed in a heavy and awkward man- 

 ner), the head is lowered, and the neck reclines over the 

 back, in order to preserve the equipoise of the body. 



PLATE 47. Represents this bird in scarcely one-third of the 



natural size. 



Average length five feet; breadth from seven to eight. General 

 Bill four inches long from the tip to the brow, black, tion. 

 and having the basal part covered with a lemon-yeUow- Adult. 

 coloured cere, that, extending backwards, encircles the 

 eyes. Head and nape of the neck generally speckled 

 with pale orange-yellow; the rest of the plumage in 

 adults being pure white. Legs black. 



The young birds are of an uniform pale grey, with the Young, 

 cere and naked skin around the eyes pale flesh-red, 

 Legs reddish-grey. 



