BRITISH BIRDS. 
48 
of the Rhine, are sometimes seen in France, but are 
most plentiful in the deserts towards the Caspian Sea, 
frequenting the dry plains in great flocks. They are 
also common throughout the deserts of Independent 
Tartary, as far as the rivers Kamyschlossca and Irtish. 
They make their nest in holes, like the Sand Martin* 
in the sandy banks of rivers, and lay six or seven 
eggs. 
