CHAP. XVIII.l 



BIKDS. 



299 



FAMILY 50. ATRICHIID^. (1 Genus, 2 Species.) 



GENERAL DISTRIBUTION. 



The genus Atrichia, or Scrub-birds of Australia, have been 

 formed into a separate family by Professor Newton, on account 

 of peculiarities in the skeleton which separate them from all 

 other Passeres. Only two species are known, inhabiting East 

 and West Australia respectively. They are very noisy, brown- 

 coloured birds, and have been usually classed with the 

 warblers, near Amytis and other Australian species. 



General remarks on the distribution of the Passeres. 



The order Passeres, is the most extensive among birds, 

 comprehending about 5,700 species grouped in 8JO genera, 

 and 51 families. The distribution of the genera, and of the 

 families considered individually, has been already sufficiently 

 given, and we now have to consider the peculiarities of dis- 

 tribution of the families collectively, and in their relations to 

 each other, as representing well-marked types of bird-structure. 

 The first thing to be noted is, how very few of these families 

 are truly cosmopolitan ; for although there are seven which 

 are found in each of the great regions, yet few of these are 

 widely distributed throughout all the regions, and we can 

 only find three that inhabit every sub-region, and are distri- 

 buted with tolerable uniformity; these are the Hirundinidae, 

 or swallows, the Motacillidae or wagtails and pipits, and the 

 Corvidse or crows, but the latter is a family of so hetero- 

 geneous a nature, that it possibly contains the materials of 

 several natural families, and if so divided, the parts would 

 probably all cease to be cosmopolitan. The Sylviidae, the 



