18 CHECK-LIST OF NORTH AMERICAN BIRDS. 
47. Larus marinus LInn. 
Great Black-backed Gull. 
Larus marinus LINN. S. N. ed. 10, I. 1758, 136. 
[B 660, C 546, R 663, C 771.] 
Geroc. Dist.— Coasts of the North Atlantic; south in winter to 
Long Island and Italy. 
48. Larus schistisagus STEJN. 
Slaty-backed Gull. 
Larus schistisagus STEJN. Auk, I. July, 1884, 231. 
[B—, C—, R—, C—.] 
Geos. Dist.— North Pacific, chiefly on the Asiatic side; Herald 
Island, Arctic Ocean, and Alaskan coast of Bering Sea. 
49. Larus occidentalis Aup. 
Western Gull. 
Larus occidentalis Aup. Orn. Biog. V. 1839, 320. 
[B 662, C 5474, R 664, C 774.] 
Groc. Dist.— Pacific coast of North America, breeding from 
Lower California northward to British Columbia. 
[50.] Larus affinis Remnu. 
Siberian Gull. 
Larus afinis Retnu. Vid. Med. 1853, 78. 
Geroc. Dist.— Northern Asia and Europe, southward in winter to 
northern Africa. Accidental in Greenland. 
51. Larus argentatus Brinn. 
Herring Gull. 
Larus argentatus BRUNN. Orn. Bor. 1764, 44. 
[B—, C 547, R 666, C 772.] 
Geroc. Dist.— Old World, south to the Azores; Cumberland 
Sound ; occasional on the eastern coast of the United States. 
