150 THE STORY OF THE BIRDS 



divided by narrow shallow seas the avifauna 

 of each is very similar in character we find 

 either the same species or others very closely 

 allied to them in both. But in the case of seas 

 of great antiquity usually very deep even 

 though in not a few cases comparatively narrow, 

 we often find that they separate avifaunae of 

 very different aspects. As examples of what we 

 mean we may instance Madagascar, an island 

 in which many families of birds commonly dis- 

 tributed over the African continent are entirely 

 absent, and on the other hand, out of a number 

 of less than 250 avine species more than 130 

 are peculiar to the island, many of which have 

 no near African allies. The reader will also 

 recall that in many cases mentioned in the 

 previous chapter Madagascar is excepted from 

 the Ethiopian range. Then we have New Zea- 

 land another group of islands surrounded by 

 ancient and deep seas presenting us with a 

 very similar series of facts. Or still more won- 

 derful and suggestive, we may instance the case 

 of two islands in the Malay Archipelago, Bali 

 and Lombok, which are separated by a very 

 narrow yet very deep and ancient sea. This 

 strait is but fifteen miles across in its narrowest 

 part, yet so effectual a barrier has it proved to 



