CATALOGUE OF BIRDS. 173 



fish. ' The small boat is occasionally sent to drive off 

 the birds, but if disturbed from one part of the nets, 

 they rapidly commence operations on another. 



After the boats have finished hauling, the birds are 

 usually satisfied, and rest in larg bodies upon the water 

 for the remainder of the day. It is by no means- 

 uncommon to meet with a flock that extends a mile or 

 two in length. 



I have noticed that when any disease has broken 

 out, and destroyed the fish on the fresh - water broads 

 in the eastern counties, that the gulls rapidly become 

 aware of the fact, and resort daily in thousands to the 

 spot, feeding greedily on the decomposing remains that 

 are floating round the banks. 



The specimens in the case were obtained on the 

 Bass Eock in June, 1867. 



LESSER BLACK BACK GULL. (IMMATURE.) 

 Case 218. 



The specimens in the present case represent the bird 

 in its various immature stages. 



They were shot at sea, off the Norfolk coast, in the 

 autumn of 1872. 



POMERINE SKUA. 



Case 219. 



Several letters recently appeared describing an 

 " extraordinary migration" of these birds. The 

 writers appear to have been ignorant of the fact that 

 large flocks may every season be met with a few miles 

 off our coasts. 



The specimens were shot in the North Sea in 

 November, 1879. 



