TROPICAL SEA-BIRDS. 269 



them as the harbingers of the tropics. The two long straight 

 narrow feathers of which their tail consists, are employed by 

 the natives of the greater part of the South Sea Islands as 

 ornaments of dress, and serve to distinguish the chieftains from 

 the multitude. 



The esculent swallow {Colocalia esculenta) — whose edible 

 nest, formed by a secretion which hardens in the air, is one of 

 the greatest dainties of the Chinese epicure — may almost be 

 considered as a sea-bird, as it chiefly inhabits marine caves in 



ESCULENT SWALLOWS' NESTS. 



various islands of the Indian Archipelago, and exclusively seeks 

 its food in the teeming waters. 



The steep sea-walls along the south coast of Java are 

 clothed to the very brink with luxuriant woods, and screw- 

 pines strike everywhere their roots into their sides or look 

 down from the margin of the rock upon the sea below. 

 The surf of ages has worn deep caves into the chalk cliffs, 

 and here the swallow builds her nest. When the sea is most 

 agitated, whole swarms are seen flying about, and purposely 

 seeking the thickest wave-foam, where no doubt they find 



