NATATORES : LARID.E. 279 



ern regions of both hemispheres. They are piratical, 

 chasing other species and robbing them of their prey. 



The Genus Larus Gulls has the bill strong, tail 

 nearly even, colors light, and head white. 



The Glaucous Gull, or Burgomaster, L. glaucus, Briinn, 

 of the Arctic regions and southward, is thirty inches 

 long, with an extent of wing of sixty to sixty-five inches. 

 The Glaucous-winged Gull, L. glaucescens, Licht, of the 

 northwest coast of North America, is twenty-seven and 

 three quarters inches long, and the wing sixteen and a 

 half inches. The White-winged Gull, L. leucopterus, Fa- 

 ber, of Labrador to the Arctic regions, is twenty-six 

 inches long, and the wing seventeen and a half inches. 

 The Great Black-backed Gull, L. marinus, Linn., of the 

 Atlantic, is thirty inches long, and the wing nine inches. 

 The Herring or Silvery Gull, L. argentatus, Briinn, of 

 the Atlantic coast and the interior of the United States, 

 is twenty-three inches long, the wing eighteen inches ; 

 the head, neck, under parts, rump, and tail, pure white ; 

 back and wings light pearl-blue. The Western Gull, L. 

 occidentalis, Aud., of the Pacific, is twenty-five inches long, 

 and the wing seventeen inches. The California Gull, L. 

 californicus, Lawr., of the Pacific, is twenty-two inches 

 long, and the wing sixteen and a half inches. The Ring- 

 billed Gull, L. delawarensis, Ord, of North America, is 

 twenty inches long, and the wing fifteen inches ; bill yel- 

 low, with a dark brown band. Suckley's Gull, L. Suckleyi, 

 Lawr., of the Pacific, is seventeen and a half inches long, 

 and the wing thirteen and three quarters inches. 



The Genus Blasipus has the bill long and rather slen- 

 der. It is represented by the White-headed Gull, B. Heer- 

 manni, Bonap., of California, which is seventeen and a 

 half inches long, and the wing thirteen and a half inches. 



The Genus Chroicocephalus has the bill rather slender 

 and much compressed, wings long, narrow, and tail usually 



