THE BIRDS OF MONGOLIA ETC. 99 



It is the first bird to arrive in spring at Lake Hanka, as a rule either 

 late in February or early in March, whilst the principal migration occurs 

 about a month later. Only a few pairs remain to breed, in the marshes 

 overgrown with reeds. 



259. Cygnus BEwiCKii, Yarr. Lehed maley. 



Together with the preceding species it was noticed at Dalai-nor in 

 spring ; but it was also seen in the Hoang-ho valley, on Lake Urgun-nor. 

 Tn Ala-shan w^e also occasionally saw migrating flocks in October, which 

 w^ere flying very high over a desert. At Koko-nor some flocks were seen, 

 which probably belonged to C bewickii ; and a few pairs evidently stopped 

 to breed there. 



260. Cygnus olor, Gmel. ? Lehed shipim. 



This species is mentioned with a ? on account of our not being able to 

 secure a single specimen, although we met with it at Dalai-nor, as well 

 as the two preceding ones ; the present bird very much differs from 

 C. musicus by its voice. 



On the 11th of April, on a small lake not far from Dolon-nor, we found 

 a Swan's nest containing one egg, which, according to its shape and colour, 

 belonged to the present species. It is an egg with a roughly grained but 

 tolerably smooth dirty-greenish shell : large diameter 3"'78, small diameter 

 2"-68. 



Besides, in S.E. Mongoha, I think we saw C. olor migrating over the 

 Koko-nor basin early in March. 



At Lake Hanka they appear much later than C. musicus, namely in the 

 beginning of April, and in larger flocks. They breed in similar locahties as 

 the preceding Swan. 



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