52 Mr. C. H. B. Grant on a Collection of 



"European birds are in full winter dress, the African birds 

 are in full summer dress. 



[Irides reddish brown ; bill brownish horn, tip of lower 

 mandible lighter ; legs and toes mottled yellow and black. 

 Many seen, shy and difficult to shoot.] 



40. Hydrochelidon leucoptera leucoptera. White-winged 

 Tern. 



Sterna leucoptera Temm. Man. d'Ornith. 1815, p. 483: 

 Coasts of the Mediterranean. 



a. ^ imm. Lake Naivasha, 6700 ft. Dec. 4. 



Total length in flesh : 9^ inches. Wing : 205 mm. 

 Bill : 25 mm. 



This bird is practically in full winter dress, but still 

 retains a few of the immature feathers in the wings 

 and tail. 



In naming this bird I have gone through the whole series 

 in the National Museum, both of this species and H. nigra 

 Linn. (Syst. Nat. 10th ed, 1758, p. 137: Europe), and have 

 noted the following differences between the species in winter 

 and immature dress : — 



H. I. leucoptera. — Adult winter. Appeai'ance of crown and 

 nape lighter (actually the black is much blacker), feathers 

 more broadly edged with white, giving a very mottled 

 appearance. Above lighter grey. 



Young. On the average more white on forehead, and much 

 whiter rump. 



H. nigra. — Adult ivinter. Appearance of crown and nape 

 darker (actually the black is more sooty). Above darker 

 grey. 



Young. On the average less white, often more fulvous, on 

 forehead, and much greyer rump. 



At all times and at all ages the bill of H. leucoptera is 

 shorter than that of H. nigra., i. e. H. leucoptera, 22-25 mm., 

 and H. nigra, 26-28 mm., taking adults only. 



Specimens in the Museum show that H. leucoptera is found 

 commonly in Africa, both east and west, and south to Cape 

 Colony ; H. nigra is apparently a rare visitor, as there are 



