30 PASSERES. 



up without ever having heard the song of its 

 species, it would be destitute of it. 



It is in this Order, also, that we find the instinct 

 of nest-building most perfectly displayed. The 

 specimens of nests which are prepared, we can 

 hardly say built, by other birds, are rude struc- 

 tures, consisting mostly of loose aggregations of 

 rough materials with scarcely an attempt at con- 

 struction. But very many of the Passerine birds 

 build most elaborate and elegant structures, of 

 which we may mention as instances, the compact 

 felted nests of the Humming-bird, of the Gold- 

 finch, and of the Bottle-tit, and the w r oven purses 

 of the Orioles and the Starlings. 



The study of this immense assemblage of spe- 

 cies is facilitated by its sub-division into four 

 Tribes, characterized by the varying form of the 

 beak, and named respectively Fissirostres, Tenui- 

 rostres, Dentirostres, and Conirostres. 



TRIBE I. FISSIROSTRES. 



The beak in this Tribe is short, but broad, and 

 more or less flattened horizontally, often hooked 

 at the tip, with the mouth very deeply cleft : the 

 upper mandible is not notched. The feet are 

 small and feeble. Most of the species feed on 

 insects, which they capture on the wing, but one 

 genus subsists on fishes. 



The tropical regions are the principal home of 

 the fissirostral birds ; such species as reach to the 

 temperate zone, are, for the most part, migratory 



