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GREAT BLACK-BACKED GULL. 165 
and intensity; neutral-tint, chestnut brown, and dark brown being 
all met with, and sometimes in the same specimen.—Fiy. 3, 
plate XII, 
310. HERRING GULL—(Larus argentatus). 
A very numerous species in many different parts of the king- 
dom, where rocky coasts sufficiently high and precipitous are met 
with. I have seen it abundantly at Flamborough Head and St. 
Abb’s Head, and in smaller numbers on many parts of the York- 
shire coast north of Flamborough, as well as im others not distant 
from St. Abb’s. It usually selects for the site of its nest a flat 
ledge or other rock-surface towards the upper part of the cliff; 
but will sometimes build on a low rock or grassy island. The 
nest is like that of the last species, but even larger, and usually 
contains three eggs. These so strongly resemble those of the 
Lesser Black-back as to make it very difficult to distingush 
between the one and the other. Mr. Hewitson says the only 
means of distinction available even to an experienced eye seem to 
depend on the somewhat greater size of the Herring Gull’s egg, 
and the larger and more confluent character of the blotches of 
surface colour.—Fig. 4, plate XII. 
311. GREAT BLACK-BACKED GULL—(Larus marinus). 
Black-back, Cob, Great Black-and-white Gull—By no means 
a numerous species, and not affecting society as so many of the 
other Gulls do. It breeds, in some cases, on the Marsh or Salting- 
spaces met with so abundantly on some of the southern and 
eastern shores; but more commonly on rocky parts of the coast. 
Thus, it breeds very abundantly on the Orkney and Shetland 
Islands. The nest is made of a large quantity cf dry grass 
simply thrown together. The eggs are three in number, often 
bearing a great resemblance to those of the two species last 
