262 BRITISH BIRDS. 



and in breadth from 1'16 to T05 inch. The eggs of the Whiskered Tern 

 are readily distinguished from those of the Black and White-winged Black 

 Terns by their larger size, smaller markings, and paler and greener ground- 

 colour. Some eggs of the Arctic Tern are almost indistinguishable from 

 those of the Whiskered Tern ; but on an average those of the former 

 species are larger and more boldly marked. Some eggs of the Little 

 Gull also very closely resemble those of this bird, but they also are 

 generally much larger. 



The accounts of the breeding of the Whiskered Tern in South Africa 

 and in Australia are very unsatisfactory. It is quite possible that it does 

 breed in both these countries, but the interest attaching to the circum- 

 stance is so great that it is to be hoped that more precise details may be 

 published. 



The Whiskered Tern is somewhat larger than the two species already 

 described, and the fork of the tail is slightly deeper. It forms a connect- 

 ing link between the Marsh-Terns and the typical Terns, having the black 

 cap of the latter, but the black belly of the former. The adult in summer 

 plumage differs from the Black Tern in having the chin, throat, lores, ear- 

 coverts, and sides of the neck white ; the under wing-coverts are also pure 

 white. Bill dark red ; legs and feet bright red ; irides dark brown. After 

 the autumn moult the black on the head is absent from the forehead and 

 is mottled with white on the crown, and the whole of the underparts are pure 

 white. 



After the spring moult the young bird differs from the adult in having 

 the lesser wing-coverts mottled with brown, and the forehead and crown 

 with white. Birds of the year differ from adults in winter plumage in 

 having pale margins and brown sub-margins to the scapulars, innermost 

 secondaries, and the tips of the tail-feathers, as well as to the wing-coverts. 

 The bill, legs, and feet are brown. 



Young in first plumage differ from birds of the year in having chestnut 

 margins and brown sub-margins to all the feathers of the upper parts, 

 including the ear-coverts. 



Young in down have the upper parts pale chestnut, mottled with black ; 

 and the underparts white, except the throat, which is brownish black. 



