THE TRUE SWANS. 255 



Cygnus olor, D/esser, B. Eur. vi. p. 419, pi. 418 (1880) ; 

 B O. U. List Br. B p. 119 (1883) ; Satmders, ed. Yarr. 

 Br. B. iv. p. 324 (1885); Seebohm, Br. B. iii. p. 476 

 (1885); Saunders, Man. Br. B. p. 405 (1889); Salvad. 

 Cat. B. Brit. Mus. xxvii. p. 38 (1895). 



(Plate LV. Fig. 2.) 



Adult Male. White all over, and distinguished from the other 

 species by the colour of the bill, which is described by Count 

 Salvador! as follows: " Lores, frontal tubercle, base of upper 

 mandible, nostrils, nail, edges of upper mandible and entire 

 under mandible, black ; remainder of the beak reddish-orange ; 

 legs and feet dull black ; iris hazel." Total length, about 5 feet ; 

 culmen, 4-2 ; wing, 27-0 ; tail, io-o; tarsus, 4-5. 



Adult Female. Similar to the male, but a little smaller, and 

 with a smaller tubercle on the bill. 



Young Birds. Sooty-grey, paler on the neck and under sur- 

 face of body ; bill and legs grey. The nestlings are covered 

 with down of a dull ashy-grey colour, which is paler and in- 

 clining to white on the lower throat and breast. 



Characters. In the Mute Swan the keel of the sternum is 

 simple, and is not entered by the trachea, as in the foregoing 

 species. The knob on the bill is also a distinguishing feature. 



Polish Swan (Cygnus immutabilis}. This supposed species 

 (Plate LV., Fig. 3) is said to have white cygnets, and in the 

 adult birds the tubercle is less developed, and the legs and 

 feet are more ashy-grey, but with regard to the latter characters 

 Mr. Howard Saunders writes : " Neither Mr. Bartlett nor I 

 could find these distinctions in old birds in the Zoological Gar- 

 dens which had been white as cygnets." Some ornithologists 

 still believe in the difference of the Polish Swan as a species, 

 and the Rev. H. A. Macpherson, in his " Vertebrate Fauna of 

 Lake-land," gives a figure of the sternum and trachea of a young 

 bird, which, he thinks, show characters defining the Polish from 

 the Mute Swan. 



On the other hand, Mr. Howard Saunders, Mr. Seebohm, 

 and most of our leading British ornithologists regard the Polish 

 Swan as only a kind of quasi-albino, probably produced by 

 domestication. This opinion is endorsed by Count Salvador], 



