306 CHARADRIIFORMES CHAP. 
Tarrock, is much variegated with dark grey or black, and has a 
blackish tip to the tail, as is the case in most fresh-water Gulls. 
Many fine colonies inhabit the loftier cliffs of Great Britain, the 
nests of sea-weed and grass being closely crowded together, and 
the eggs exhibiting softer colours than is usual in the Sub-family. 
The darker A. brevirostris of Bering Sea has red feet. 
Pagophila eburnea, the Ivory Gull, seems truly circumpolar, 
while it accidentally visits Britain, Northern Europe, and New 
Brunswick. It is pure white, with black feet, the young shew- 
ing grey and black variations. It will eat whale- or seal-offal. 
Leucophaeus scoresbii, of South Patagonia, the Falkland 
Islands, and the neighbouring Antarctic seas, has a crimson Dill, 
coarse red feet, with somewhat excised webs, a dark hood in 
immature examples, and a white tail. Gabianus pacificus of 
Australia and Tasmania is somewhat like Larus marinus, but 
has a very short stout bill and a black-banded tail. 
In the genus Larus, as throughout this Family, the arrange- 
ment followed is that of Mr. Howard Saunders,’ much of whose 
admirable work is here incorporated. His first section com- 
prises species with a white tail but no hood, the young having 
the head striated. Of these, Z. glaucus, the Burgomaster or 
Glaucous Gull, and LZ. leucopterus, the Iceland Gull, are the only 
members of the group with nearly white primaries, the former 
being larger, with proportionately shorter wings. In summer 
the former is circumpolar, and the latter occurs from Jan Mayen to 
Greenland and perhaps the west side of Baffin Bay; in winter 
both visit Britain, but the latter only reaches the Gulf of Gas- 
cony, and Boston in America, whereas its ally extends to the Medi- 
terranean, the Caspian, Japan, California, and the Bermudas. At 
this season the head shows brown markings; while the young are 
entirely mottled, though they apparently become creamy white 
just before assuming the grey mantle. L. glaucescens of the 
North Pacific, Z. nelsoni of North-West America, and L. kumlieni 
of Cumberland Sound have the quills chequered with grey, and 
connect the above with the following or blacker-quilled group. 
L. argentatus, our Herring Gull, has a blue-grey mantie; the 
black primaries shew white tips and “mirrors” or round white marks, 
as well as a grey wedge on the inner web ; the feet are flesh-coloured, 
1 Cat. Birds Brut. Mus. xxv. 1896; J. Linn. Soc. xiv. pp. 390-406; P.Z.S. 
1876, pp. 638-672, 1878, pp. 155-212. 
