THE WORLD'S BIRDS. 



95 



Bengalee {Uroloncha acuticauda). A white breed 

 of the Jackdaw {Coloeus monedula) appears to 

 exist on the Continent. 

 Distribution and Important Species. — The Passerine 

 birds comprise more than half the known species 

 of the bird class, and are in most countries the most 

 numerous in species and individuals ; they are 

 found all over the world ; a large number are 

 migratory. Few individual species, however, have 

 the wide distribution often found in other groups ; 

 the most widely-ranging bird of the family is our 

 Sand-martin {Cottle riparia), found, according to 

 season, all over the northern hemisphere. 



The numerous subdivisions of this huge family 

 are commonly treated as families, but this is mis- 

 leading, as they are only of subfamily value. With 

 the exception of a few, such as the Swallows, 

 they are very difficult to define exactly, their 

 limits being in many cases quite undefined, and 

 being differently assigned by different authors. 

 The arrangement given below — in which the sub- 

 families are arranged in alphabetical order — may 

 be taken as fairly representing the usual view of 

 what are distinct groups and what species may be 

 assigned to them. But to learn the sub-groups 

 of Passerine birds it is before everything necessary 

 first to make the acquaintance of typical species 

 of the various divisions, such as those given under 

 each heading. 



American Warblers [MniotiltincB) are small delicately- 

 shaped birds of, usually, tree-haunting and insectivor- 

 ous habits, much like the Old World warblers in form 

 and size ; but they show gay and varied colours, and 

 as they are only found in the New World, are the less 

 likely to be confused with the true Warblers. They 



