116 BIRDS OF NORFOLK. 



course along tlie line of our north-east coast from 

 Scotland to tlie mouth of the Thames." One of four 

 examples shot at that time on the Med way, where a 

 flock of thirty and other smaller flocks had been seen, 

 was exhibited by Yarrell at a meeting of the Zoological 

 Society (Feb. 13th, 1838), and was the type on which he 

 founded the claims of this swan to be considered speci- 

 fically distinct from Cygnus olor ; for, to use his own 

 words ("Brit. Bds.," 2nd ed., vol. iii., p. 227) :— 



"The circumstance of these flocks being seen without any 

 observable difference in the specimens obtained, all of which were 

 distinct from our mute swan ; the fact also that the cygnets, as far 

 as observed, were of a pure white colour, like the parent birds, and 

 did not assume, at any age, the grey colour borne for the greater 

 part of the first two years by the young of the other species of 

 swans, and an anatomical distinction in the form of the cranium, 

 which was described by Mr. Pelerin in the Magazine of Natural 

 History (1839, p. 178), induced me to consider this swan entitled to 

 rank as a distinct species, and in reference to the unchangeable 

 colour of the plumage, I proposed for it the name of Cygnus 

 immutahilis." 



Having so far quoted from the earlier records re- 

 specting this swan, I may here introduce Yarrell's sub- 

 sequent remarks in a letter to Mr. Thomas Southwell 

 (before referred to), in which, under date of January 2nd, 

 1852, he expresses his belief that the two Ingoldisthorpe 

 specimens, sent to Mr. Bartlett, belonged to the newly 

 recognised species. Besides this result of his visit to 

 Mr. Bartlett, he writes, " I learned something more on 

 the subject you may like to know." 



" In the sale catalogue of the collection at Knowsley, the pro- 

 perty of the late Earl of Derby, was a pair of the immutahilis, 

 which Mr. Gurney, it appears, went to buy. At the sale, also, 

 among others was Mr. Bartlett, and a Dutch zoologist named 

 Westerman.* The latter told Mr. Gurney that he did not 



* Dr. Westerman, the director of the Zoological Gardens in 

 Amsterdam. 



