550 



it is, however, less abundant than the Arctic Tern, with 

 which it is frequently found breeding, although the two 

 species generally keep a little apart from each other, occupy- 

 ing different islets or portions of the same coast. South- 

 wards the Common Tern replaces the Arctic, with a few 

 exceptions, which will be noticed when treating of that 

 bird ; and along the coast of England and Wales it is dis- 

 tinctly the predominant species. From Norfolk, along the 

 east and south coasts, it has several breeding stations ; 

 but in the Scilly Islands, it is stated by Mr. Eodd to be far 

 less numerous than the Arctic Tern. 



In Ireland the Common Tern is distinctly the more abun- 

 dant species, breeding all round the coasts, and on many of 

 the salt and fresh-water loughs. Its arrival in the British 

 Islands takes place in May, and the autumnal migration 

 lasts from August to October. It ascends rivers for a con- 

 siderable distance, and has often been observed on small 

 pieces of water far inland ; it is even by no means un- 

 common to see a few birds hovering over the Serpentine and 

 other sheets of water in or near the metropolis. 



The Common Tern is generally distributed, during the 

 breeding-season, on the coasts and rivers of Europe, from 

 Norway to the extreme east of the Mediterranean, as well as 

 in the islands of the Atlantic. Crossing that ocean, this 

 species is abundant in North America (where it was for- 

 merly distinguished as S. ivilsoni by Bonaparte), from 

 Labrador to Texas ; and the Editor has examined specimens 

 obtained at Cumana in Venezuela, and at Bahia in Brazil, 

 in autumn. It has not, however, been recorded as yet from 

 the Pacific side. 



Returning to the eastern hemisphere, we find this Tern 

 in Western Asia, and on the shores of the Bed Sea, strag- 

 gling to the coasts of India in winter. On the elevated 

 lakes of Kashmir, Tibet, and Southern Siberia as far east 

 as Lake Baikal, it appears to be replaced by a form which 

 the Editor has distinguished (P. Z. S. 1876, p. 649) by 

 the name of Sterna tibetana. The latter, in breeding-dress, 

 has the sides of the neck, shoulders and flanks, of a clear 



