120 BIRDS OF NORFOLK. 



the bill, thus differing even from the female mute 

 swan at the same age. The smallness and flatness of 

 the tubercle, or "berry," has been a particularly marked 

 feature in all the specimens of this swan I have seen, 

 and its upper surface has been usually studded with 

 minute feathers, as remarked also by Mr. Southwell in 

 the Ingoldisthorpe birds. Macgillivray points out the 

 smallness of the eye, giving the measurement of the 

 aperture as five-twelfths and a half. This is very notice- 

 able in the head of the Hoveton specimen now before 

 me, as also the fact (observable in the pair at the Zoolo- 

 gical Gardens) that the triangular black patch at the 

 base of the bill meets the eye anteriorly, and does not 

 partially encircle the eye, as in adult specimens of C. olor, 

 the difference being plainly shown in the heads of these 

 two swans as figured by Yarrell. The same writer also 

 contrasts the position of the nostrils in the Polish with 

 those of the mute swan, stating that the nasal aperture 

 in the former is surrounded by the orange colour of the 

 beak, and does not, as in the latter, join the black at the 

 base of the beak. This distinction, however, like the 

 grey colour of the feet and legs before referred to, 

 cannot, I think, be relied upon as a specific distinction, 

 as I recently took some pains to examine with a glass 

 the heads of several old as well as young mute swans 

 on the river, and satisfied myself, in every instance, 

 that the orange or pink colour of the beak, accordmg 

 to age, surrounded the nostrils, although the overhang- 

 ing of the great black tubercle in adult males, at first 

 sight, conveyed a contrary impression. A much more 

 important difference, however, presents itself on com- 

 paring the heads of C. immutahilis and 0. olor, viz., the 

 curvature in the ridge of the upper mandible in an old 

 mute swan, as contrasted with the comparative straight- 

 ness of the same portion of the beak in the Polish swan. 

 Judging from the specimens in the Zoological Gardens, 



