280 



VERTEBRATES : BIRDS. 



even. The colors are mainly dark above and light be- 

 low, and these are in beautiful contrast. In spring and 

 summer the head is dark, but in winter white. Five 

 species belong to North America. The Laughing Gull, 

 C. atricilla, Linn., of New England to Texas, is seventeen 

 inches long, the wing thirteen inches. Bonaparte's Gull, 

 C. Philadelphia, Lawr., of all North America, is fourteen 

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



TheGenus^z>.5Y? comprises the Kittewakes, of the north- 

 ern regions, which are fourteen to seventeen inches long. 

 The Genus PagopJiila Ivory Gulls has the webs 

 of the feet indented. The gulls of this genus are Arctic, 

 found far from land, are about eighteen or nineteen inches 

 long, and mostly pure white. 



The Genus RJiodostetJda contains the Wedge-tailed Gull, 

 R. rosca, Jard., of the Arctic regions, which is fourteen 

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



The Genus Creagnts contains the Swallow-tailed Gull, 

 C.furcatus, Bon., of California ; and Xema the Fork-tailed 

 Gull, X. Sabinii, Bon., of the North Atlantic, which is thir- 

 teen and a half inches long, and the wing eleven inches. 

 Fig 146 The Genus Sterna comprises 



the Terns, which have the bill 

 slender, wings long and pointed, 

 tail long and forked. They are 

 generally white or light below ; 

 black, and bluish or bluish gray, 

 above. They feed upon small 

 marine animals, which they dart 

 down upon. Fourteen or more 

 species are found on the coasts 

 of North America. The Marsh 

 Tern, 5. aranca, Wils., of the 

 Atlantic coast as far north as 

 Connecticut, is nearly fourteen 



