THE CASPIAN TEEN. 405 



When we consider the descent of so many great rivers, in 

 so many directions, into that great basin, and that the upper 

 streams of all rivers which are in mountain ridges, overlap 

 each other in the flexures of these, we can see easily why 

 birds of an Indian character may be found in that part of 

 the world, or may even reach the shores of England from 

 thence. The pratincole is one instance, the bird under 

 notice is another, and the one next to be mentioned is a 

 third. We have no perfect natural history of that very sin- 

 gular portion of the earth's surface ; and some parts of it are 

 vague and unsatisfactory, even in respect of that very slender 

 information which is afforded by the common topographical 

 map. The snows of the Alps, of the Ural, and the Hindu 

 Coosh, if not of the Himalaya, are melted, roll down their 

 several rivers, and again raised by evaporation, frozen, and 

 cast anew in snow upon Caucasus ; and where there is this 

 singular meeting of distant waters, we may naturally enough 

 look for some community among the creatures which these 

 waters support, especially those families of them which are 

 so discursive as the terns. 



THE CASPIAN TERN (Sterna caspia). 



This species also belongs to the eastern migration, as indeed 

 its name imports ; for it is abundant on the great salt or 

 inland sea, after which it is called. The probability is, that 

 the centre of its range in longitude lies more to the eastward 

 than that of the former species, and it extends very near at 

 least to the Indian mountains. It is a large species, mea- 

 suring nearly two feet in length, with the wings long in pro- 

 portion ; so that while it has all the characters of a true tern 

 in much greater perfection than the gull-billed tern, its size is 

 nearly the medium of that of the gulls. It does not appear 

 to be so discursive a bird as several of the smaller terns ; but 



