AVES. 389 



follow ships for immense distances, for the purpose of picking up such ai-ti- 

 cles suitable for their food as may be thrown overboard. The cape pigeon, 

 Procellaria capensis {pi. 91, fg. 11), and the storn)y petrel {Thalassidroma 

 pelagica), are common species. 



Fam. 5. Larid^. This extensive family embraces all the common and 

 generally handsome sea-birds known by the names of gulls and terns. They 

 are natives of the sea-shores of all countries. 



Sub-fam. 1. Larincc, or Gulls. Bill rather long, straight, curved at the 

 tip, which is acute; wings long, pointed ; tail moderate; tarsi short, strong; 

 feet moderate, fully webbed. Size various; colors mostly white, and light 

 cinereous. ^ 



Nearly fifty species of these birds are scattered over the marine portions 

 of the world, sometimes, during winter, being found in the marshes or on 

 the borders of rivers, but returning to the sea coast during summer. They 

 are generally gracefully formed birds, with pure white or cinereous plumage. 

 The black-headed gull {Larus atricilla), the kittiwake {L. rissa), the ivory 

 gull, L. eburneus {pi. 91, fg. 5), a beautiful pure white species, the burgo- 

 master {L. glaucus), the black-backed gull or saddle-back {L. marinus), and 

 the herring gull, L. argentatus {pi. 92, fig. 11), are the principal species of 

 the American sea-coasts, and are also found on those of Europe. 



Sub-fam. 2. Sternince, or Terns. Bill rather long, slender, straight, sharp; 

 wings very long, pointed ; tail long, generally forked ; tarsi and feet short ; 

 Size various ; color mostly white. 



These handsome birds, known on the Atlantic coasts of the United States 

 by the name of sea-swallows, frequent all the sea-coasts of the world. They 

 are continually on the wing, and their flight is frequently elevated, but at 

 other times near the surface, and of long continuance. When seeking their 

 food, which consists of small marine animals, they generally perform large 

 circles, and, upon discerning a suitable object, suddenly dart upon it. At 

 other times they sweep over the surface of the water in the manner of 

 swallows, seizing with their bills any floating objects. The great sea swal- 

 low, Sterna hirundo {pi. 92, fig. 12), the little tern {S. minuta), and the sooty 

 tern, S. nigra {pi. 91, fig. 4), are common species. 



There are nearly one hundred species of terns. 



Fam. 6. Pelecanid^. Contains the pelicans, cormorants, tropic birds, 

 and some others. They are generally large and powerful birds, and inhabit 

 principally the southern hemisphere. 



Sub-fam. 1. PhcBtonince, or Tropic Birds. Bill rather long, broad at base; 

 wings long, pointed ; tail moderate, two middle feathers lengthened ; tarsi 

 and feet short. Size rather small ; color white. 



Four or five species of these birds inhabit the southern seas, and are 

 usually observed at a considerable distance from land, skimming over the 

 surface of the water, seizing such fishes and other marine animals as 

 approach the surface. They are the especial enemies of the flying fish, 

 and are said to rear their young in hollow trees or in the fissures of rocks. 

 The white tropic bird, Phceton ccthereus {pi. 92, fig. 4), is a good example 

 of these birds. 



inONOGKAiniC EXrYCLOl'iBDIA. — VOL. II. 38 693 



