NATATORES. 261 



but the former also differ inter se in summer and 

 winter. An old bird, killed in June, had the tarsi 

 and toes bright yellow, while another adult bird, 

 shot in February, had the same parts greyish green. 

 Two old birds, procured in October, exhibited the 

 yellow colour only around the tarsal joint, the rest 

 of the leg and foot being pale greenish grey. Tem- 

 minck calls this species " Mouette d pieds bleus." 



LESSER BLACKBACKED GULL, Larus fuscus. In a 

 list of water-birds occurring at Kingsbury Reservoir, 

 published in ' The Zoologist ' for 1843, the occur- 

 rence of the Lesser Blackbacked Gull is recorded ; 

 but it is a rare bird in Middlesex, and only met with 

 in severe weather, or after there has been a preva- 

 lence of east wind. I have seen a young bird of 

 this species, which was shot at Kingsbury Reservoir, 

 in autumn ; and in October, 1865, "William Sawyer, 

 the keeper at this reservoir, killed a fine old bird in 

 good plumage. 



Gulls appear to be longer in arriving at maturity 

 of plumage than, perhaps, any other class of birds. 

 Many species attain the adult plumage after the first 

 moult ; but I believe most, if not all, of the Gulls 

 pass three years in a state of gradual transition 

 before they display the colours of their parents. 

 Whether they pair and breed before they have 

 assumed the adult plumage has not yet, so far as I 

 am aware, been ascertained, but my own observa- 

 tions lead me to think that they do not. 



