POLISH SWAN. 187 



TYhen the young are hatched, the old female will sometimes carry them on her back, 

 when swimming about; and we believe this to be the practice of many of our aquatic birds. 



In the adult male, the bill is orange red, the nail, base, lore, and tubercle, black. 

 Irides, brown. The whole of the plumage is of a pure white. The legs and feet are 

 black. 



The female, -which is somewhat smaller than the male, has the neck more slender, 

 and swims more deeply in the water. 



The young birds, before their first autumnal moult, are of a blue gray colour; the 

 beak, lead-colour. After their second autumnal moult, they are almost white, and can 

 hardly be distinguished from the old birds. 



The Tame Swan weighs from twenty-five to thirty pounds. 



In length it occasionally measures as much as five feet: but is generally from four 

 to six inches shorter. 



The trachea is simple, entering directly into the lungs, and does not traverse the 

 breast-bone, as in the Swans already described. 



POLISH SWAN, (Cygnus immutabilis.) Tarrell. 



This Swan was confounded with the other Swans until the year 1836; and in 1838, 

 a specimen was exhibited by Mr. Tarrell, at a meeting of the Zoological Society, and 

 described under its present name. Mr. Tarrell states, that "during the severe weather 

 of January 1838, several flocks of these Polish Swans were seen pursuing a southern 

 course along the line of our north-east coast, from Scotland to the mouth of the Thames, 

 and several specimens were obtained." 



The Polish Swan is known to frequent the Baltic sea, from whence specimens find 

 their way to this country. Its farther geographical range seems not to be known. 



The Polish Swan has bred in Ireland, as mentioned by Mr Thompson; he says — 

 "In August 1843, a bird preserver in Dublin, shewed me a Cygnet of a whitish gray 

 colour, which puzzled him very much. He stated that it was the produce of a pair 

 of Swans purchased by a gentleman, living in the neighbourhood of Dublin, a few 

 years previously, in London, and whose Cygnets were always 'white,' instead of the 

 ordinary gray colour." 



This peculiarity, in the young birds being of the same colour as the adults, induced 

 Mr. Tarrell to give it the name of 'immutabilis,' or, which does not change; certainly 

 a very suitable name, and one which cannot be appropriated by any of our other 

 Swans, whose young are all gray for the first two years. 



