tlie Birds of the Lower Petchora. 455 



plied with cartridges we might have secured many more. 

 About a dozen or fifteen Gulls {Larus affinis, Reinhardt) were 

 frequenting the same ground ; but these at once took their 

 departure and did not return. On several occasions we ob- 

 served the peculiar Kestrel- or Tern-like hover of the BufFon's 

 Skua on wing, and also saw these birds pick up from the 

 ground, or seize upon the Aving, Dunlins and Stints, in the 

 one case acting like a Hen- Harrier, in the other seizing their 

 prey like a Falcon. We had cause also to suspect their 

 depredations amongst the eggs ; and Grey Plovers and other 

 birds often joined in driving them away from their domains. 

 Sometimes, in the evenings or mornings, we saw long strag- 

 gling flocks of these Skuas passing over the island of Alex- 

 ievka, and crossing and recrossing the branch of the Petchora 

 which separates that island from the fastland. We found 

 them common all over the tundra as far north-east as we 

 penetrated. 



In the specimens of the two species which we obtained we 

 found a marked difference in the coloration of the legs and 

 toes, those of the Richardson's Skua being uniform dark 

 brown, while those of Buffon's Skua were blotched with bluish 

 grey. In one specimen of the latter there is a single feather 

 of the under tail-coverts white, with dark brown bars ; in all 

 the other specimens procured the under tail-coverts are of a 

 uniform smoky brown. This single feather is doubtless a 

 last trace of immaturity. 



Obs. We saw many specimens of the Pomatorhine Skua 

 outside the Golaievskai banks on our journey home by sea, 

 but saw nothing of this species during our stay in Russia. 



COLYMBUS SEPTENTRIONALIS, L. 



We added this species to our list on the 12th June as we 

 were descending the river, when one was shot from the boat. 

 Afterwards we met with it sparingly on the tundra and ob- 

 tained their eggs ; but the next species appeared to be certainly 

 the more abundant of the two. 



CoLYMBUS ARCTICUS, L. 



We identified the Black-throated diver first at Ilabariki, ou 



