HYDROCHELIDOK.— HYDEOPROGNE. 221 



(i.) Tail-feathers rounded or slightly pointed (236, 237). 



Genus HYDROOHELIDON. 



i)Sw/)=TS'ater; xE'^'5iii' = a Swallow. 



Bill long and slender. Tail short, less than half length of wing. Webs deeply 

 niarginate. 



236. Hydrochelidon leucoptera. The Whitk-winged Black Marsh-Tben. 



LeucopUra='KevKbirTepoi, white-winged; from XeuK6s + 7rTep6v. 



$ 9" to 10". Legs red. Bill livid red in summer, blackish in winter. Head, 

 neck, mantle, below, and wing-lining black. Upper tail-coverts and tail white. — 

 In winter: Parti-coloured and below white. Temperate Europe and Asia south of 

 55° N. lat. in summer. Africa to Australia in winter. Often met with in Ceylon, 

 but not identified in India west of Tipperah. Eggs (L3 x 0'9) chocolate, blotched 

 grey and brown. (B. 1497.) 



237. Hydrochelidon hybrida. The 'Whiskeebd Marsh-Tern. 



Sy})rida=a, mongrel, hybrid ; because Pallas thought it like a hybrid between H. nigra and 

 Sterna fiuviatilis. 



$ 10" to 11". Legs dull red. Bill lake. Forehead, crown, and nape black. 

 White eye-line. Chin, cheeks, throat, vent, under tail-coverts and wing -lining 

 white. Abdomen dull black. Upper tail-coverts and tail grey. — In lointer : 

 Front and round bill white. Beneath white. S.W., C, and S. Europe, Africa, 

 Asia, to China and Australia. Three eggs (1-51 x 1-09), olive, spotted purple 

 and brown. Breeds along the Danube and in the Orange Eiver Colony, forming a 

 curious but not the only instance of a bird nesting both north and south of equator. 

 (J. 984. B. 1496.) 



Also H. nigra. 9J" to 10". The Black Tern. Legs red-brown. Bill black. Head and 

 neck black. Mantle and wings slate. Breast and abdomen dark lead colour.' — In winter: 

 Forehead white, crown and nape mottled. Europe south of 60° N. lat., Africa. Not traceable 

 in Asia beyond W. Turkistan. 



H. surinamensis. 9J". Similar to H. nigra, but abdomen deep black. Temperate K. 

 America to S. America in winter. 



Also the genus Phaethusia, with webs slightly indented. One species — P. magnirostris, 

 14f". Legs olive, webs yellow. Bill yellow. Head and nape black, with narrow white 

 line at base of bill. Mantle and tail slate-grey. Primaries dark brown, with whitish wedges 

 on inner webs. Below white. S. America. 



(ii.) Outer tail-feathers longest, pointed. (238-254.) 

 Genus HYDROPROGNE. 



Bill stout and deep. Tail emarginate, short, rather more than one-third length 

 of wing. Webs fully developed. 



238. Hydroprogne caspia. The Caspian Marsh-Tern. 



(J 18" to 20". Legs black. Bill coral-red. Head and nape black. Above 

 pearl-grey. Back, neck, and below white. Some primaries edged and tipped. — In 

 winter : Head white, with black streaks. (J. 982. B. 1498.) See illustration, p. 222. 



