I04 THE STORY OF THE BIRDS 



the Geographical Distribution of Birds, or the 

 way in which the various species that compose 

 those orders are dispersed over the earth's surface. 

 In the previous chapter we commenced by divid- 

 ing living birds into two great sub-classes, the 

 Rheas, Cassowaries, Emus, Kiwis, and Ostriches 

 forming one of these, called Ratitae, and all 

 remaining birds forming the other, called 

 Carinatae. Ratitae birds we have divided into 

 four orders with living representatives, whilst 

 Carinatae birds have been separated into twenty 

 orders. Let us now briefly consider how the 

 various species that form these twenty-four 

 orders of birds are .distributed over the earth's 

 surface. The first really scientific effort to do 

 this was made by Dr. Sclater, who divided the 

 world longitudinally into six great avifaunal 

 regions. This was followed a few years later 

 by a scheme of which Huxley was the author, 

 in w^hich he considered that the earth's surface 

 was better divided latitudinally, and that four 

 regions were preferable to Dr. Sclater's six. 

 Eight years later still. Dr. Wallace published his 

 great book on the geographical distribution of 

 animals, in which he adopted Dr. Sclater's views, 

 and these have been more or less generally 

 accepted ever since. Although many grave 



