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 (Cotile 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 (Mniotiltincz) 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 



