BLACK -HEADED GULL. 477 



They are also abundant at the same season on the river Clyde, in 

 the very heart of the city. 



Another numerous colony of Black-Headed Gulls has for many 

 years frequented the island of Inchmoin, on Loch Lomond. This 

 island, which is about two miles in circumference, is quite flat, 

 and stands but little above the level of the water. In wet 

 seasons, therefore, it is to a great extent converted into a wet 

 marsh. About the centre, where the ground is firmer, the Gulls 

 construct their nests, which in some cases measure about eight 

 inches in height, so that the contents are always safe against 

 damp. Here, as well as at Hairlaw, many of the nests contain 

 four eggs, though three is the usual number. Great variety also 

 exists in the markings some being pale blue and slightly spotted, 

 others entirely of a dark colour, like some varieties of the egg of 

 Richardson's skua. In one nest on Tnchmoin I found a nest with 

 two eggs one of which was much elongated, pale green in colour, 

 and spotless; while the other was much shorter, nearly twice the 

 thickness, and almost as black as a piece of bog oak. 



In February, 1870, I examined eight specimens of this gull, 

 which were shot at Girvan. Two were adults, in full winter 

 plumage, with coral-red bill and legs ; two were apparently of the 

 third year, with the bill and feet orange, inclining to red; the 

 remainder being of various ages, from the first year to the end of 

 the second, legs and bill of a dull, yellowish tint. There were not 

 two alike, either in the quill markings, colour of feet and bill, or in 

 the dimensions of the bill. The orbits in two of them were red ; 

 but in another, which was just assuming the black cap, and had 

 the rest of the plumage identical, the orbits were black. . The 

 general measurements of all the specimens also diifered consider- 

 ably. There seems to be considerable variation in the space 

 occupied by the dark brown feathers on the head of this bird. 

 The variety known as the Masked Gull (Larus capistratus) has 

 several times occurred in Aberdeenshire, as I have been informed 

 by Mr Angus. I examined a fine specimen in Mr Mitchell's 

 collection, which had been shot near Don Mouth in 1867, and 

 also one in Mr Angus's collection, killed about the same time and 

 place. The white spot near the eye of Mr Mitchell's specimen 

 appeared to me to be larger than that seen on L. ridibundus; but in 

 other respects as regards the measurements and general markings, 

 excepting of course the masked form of the black cap, the two 



