314 CHARADRIIFORMES CHAP. 
which the last two are said to lay a single egg. S. albistriata, 
with but slightly elongated outer rectrices, yellow bill and feet, 
inhabits New Zealand and strays to Norfolk Island; S. forster:, 
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, Seena aurantia, 
of India, the Burmese countries and Yunnan, has the bill and 
feet orange ; Hydroprocne 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. Phaéthusa 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 
egos 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 /Z. swrinam- 
ensis inhabits temperate America from Alaska and Canada south- 
wards, migrating to Chil 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. . hybrida, 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 
