134 AQUATIC FOWL. 



very valuable, and is procured in great quantity by the Icelanders. 

 In the month of August, when the old birds have cast their quill 

 feathers and are unable to fly, the natives, attended by dogs, and 

 mounted on horses, ride them down or take them by the dogs. In 

 swimming it is never seen to throw up the plumes of its wings, or 

 assume any striking attitude ; and it carries its neck erect and straight, 

 instead of curved; but while walking its head is lowered. In 

 captivity it soon becomes tame, and has bred in England. It has 

 no basal protuberance on the upper mandible ; the cere, as far as 

 the eye, is yellow, as is also the back part of the lower mandible ; 

 the point as far as the nostrils, black these two colours meet each 

 other obliquely, the yellow advancing forward along the sides of 

 the beak; iris brown, feet black. Expanse of the wings, about 

 eight feet. 



THE BEWICK SWAN 



Is about one- third less than the hooper ; its beak rises high at the 

 base, which is yellow ; the anterior portion, including more than 

 the nostrils, black ; the tail feathers are eighteen, in the hooper 

 twenty ; the legs are of a deeper black than the hooper, and the 

 neck is more slender. The arrangement of the trachea is very 

 different. The tube of the windpipe is of equal diameter through- 

 out, and descending in part of the neck, enters the keel of the 

 sternum, which is hollow, as in the hooper, traversing the whole 

 length. Having arrived at the end of the keel, the tube, then 

 gradually inclining upwards and outwards, passes into a cavity in 

 the sternum, destined to receive it, caused by a separation of the 

 plates of bone, forming the breast-bone, and producing a convex 

 protuberance of the inner surface. This swan is a native of the 

 northern regions of Europe and Asia, as well as America; it 

 breeds in Iceland, and within the artic circle, migrating south- 

 wards in spring ; it appears to be much scarcer than the hooper. 

 The nest is large and deep ; its cry is loud ; in captivity its note 

 is a low-toned whistle ; its voice is much weaker than the pre- 

 ceding species . There has been a fine specimen of this swan for 

 some years in our Dublin Zoological Gardens. 



THE POLISH SWAN 



Has been confounded with the tame swan, to which, of all the 

 European swans, it is most nearly related. There are, however, 

 many important anatomical differences, especially as to the head- 



