POLISH SWAN. 119 



possibility that two distinct birds have been confounded 

 under the name of "Polish" swan, one the so-called 

 Cygnus immutabilis, the race which produces white 

 cygnets, the other the original wild race of Cygnus 

 olor. Unfortunately, as Mr. Gurney remarks, "we 

 do not know the diagnosis between these two birds 

 accurately, and therefore cannot be sure whether the 

 swans which occasionally occur on our coast in a wild 

 state, belong all to the first or all to the second, or some 

 to each." Mr. Gurney, also, reasoning from analogy in 

 the case of the Swan-goose (Anser cygnoides), so common 

 in our parks and ornamental waters, and found wild in 

 so many parts of Asia, suggests the probability that the 

 tubercle on the base of the beak of our tame swans 

 may, on comparison with examples of the wild race of 

 (7. olor, be found to have largely developed during years 

 of domestication. 



Pending the settlement, then, of this vexed question 

 by competent authorities, I will conclude this notice 

 with a few remarks on the external differences,* pointed 

 out by Yarrell and others, between the Polish and the 

 mute swan of our home waters, and such as have more 

 particularly struck me in the examination of some three 

 or four examples of this disputed species. 



Besides the very important cranial differences quoted 

 by Yarrell from Mr. Pelerin's paper in the Magazine 

 of Natural History, and which he states were fully 

 verified by himself, we have that author's statement, 

 also, that an old male Polish swan, in its ninth or 

 tenth year, had but a small tubercle at the base of 



* The trachea of the Polish swan, according to Yarrell, 

 resembles that of the mute swan, and though, from the exami- 

 nation of an adult male, Macgillivray points out some slight 

 difference in this organ, in all other respects its internal construc- 

 tion seems to be the same as in C. olor. 



