314 CHARADRIIFORMES 



which the last two are said to lay a single egg. ;S'. alhistriata, 

 with but slightly elongated outer rectrices, yellow bill and feet, 

 inhabits New Zealand and strays to Norfolk Island ; S.forsteri, 

 with white under parts, orange bill, and reddish feet, inhabits 

 most of North America. >S'. melanogaster of India, reaching 

 northwards to Afghanistan and Bhutan, has a black belly. 



Of forms with much stouter bills than Sterna, Scena aurantia, 

 of India, the Burmese countries and Yunnan, has the bill and 

 feet orange ; Hydrojjrocne caspia, the Caspian Tern — largest of the 

 Sub-family — has a very short tail, red bill, and black feet. The 

 latter occupies most of the world, except tropical South America 

 and the Pacific Islands, visiting Britain, and breeding as near 

 to it as Sylt. Gelochelidon anglica, the Gull-billed Tern, with a 

 long metatarsus, reddish-black beak and feet, occurs in Britain 

 and is found through the temperate and tropical "parts of the Old 

 and New Worlds, but not in South Africa, and rarely in Western 

 America. Pha'ethusa magnirostris, of the warmer portions of 

 North America, has a short tail, yellow bill, and olive-yellow feet. 



The genus Hydrochelidon, or Marsh Tern, is distinguished by 

 a short tail, a comparatively small bill, and feet with much in- 

 dented webs. The note is shrill ; the food consists of aquatic 

 insects, varied by frogs, newts, and small fish : the nests, placed 

 in close proximity on swamps or pools, are formed of water 

 plants and are sometimes mere floating masses of them ; the three 

 eggs are often very dark olive or brown. H. nigra, the Black Tern 

 or Blue Darr, ranges from Europe south of lat. 60° N. and the 

 Mediterranean to Turkestan, wintering as far as Loango and 

 Abyssinia. It bred in the east of England up to 1858, since 

 which date a nest is quite exceptional, while its two congeners are 

 only chance visitors. The colour is lead-grey, with blacker head, 

 black bill and reddish-brown feet. The darker race H. surinam- 

 ensis inhabits temperate America from Alaska and Canada south- 

 wards, migrating to Chili and Brazil. H. leucoptera, the White- 

 winged Black Tern, is found in Central and Southern Europe, tem- 

 perate Asia and North Africa ; reaching accidentally to America, 

 and in winter from Cape Colony to Australia and New Zealand. 

 It is chiefly black, with white carpal region, rump, tail, and vent, 

 the bill and feet being red. H. hyhrida, the Whiskered Tern, has 

 a similar range, but breeds also from India to Australia. The 

 main colour is slate-grey, the head and nape being black, the bill 



