106 THE BIRDS OF MONGOLIA ETC. 



earlier. In the Hoang-ho valley, on Lake Tsaidemin-nor, towards the end 

 of July, we killed a male bird, which was moulting very quickly. At 

 Koko-nor these Ducks appeared on the 14th of March, and were common 

 throughout that month. 



It migrates to Lake Hanka early in March, and becomes most abundant 

 towards the end of that month, leaving the locality about that time in flocks, 

 together with other species of this genus ; and only a few pairs remain to 

 breed. 



273. FuLix CRisTATA, L. Niroc chernet. 



Is not scarce during the spring migration in Mongolia and at Koko-nor. 

 At the latter place Fulix cristata appeared on the 5th of March, and perhaps 

 even earlier still, and, together with Bucephala clangula, inhabited the river 

 Buhain-gol ; but towards the end of the month most of them had left. 



At Lake Hanka the migration takes place between the SOth of March 

 and the middle of April ; and only a few pairs remain to breed. 



274. Aythya ferina, L. Niroc crasnogolovoy. 



We once met with some migrating pairs at the northern bend of the 

 Hoang-ho at the end of April 1872, and, another time, at Koko-nor in 

 March. It does not inhabit Lake Hanka. 



275. Bucephalus clangula, L. Niroc gogol. 



Tolerably common at the Dalai-nor at the end of March and beginning 

 of April, on those parts of the lake which are free from ice ; and when shot 

 at they rise, but very soon settle down again. 



At Koko-nor they arrive about the 4th of March, and get rather 



