XXIII] LIFE IN LONDON 397 



chain of islands according as they are of Javan or Australian 

 origin, we have the following results : — 



Javan species 36 Australian species ... 13 



Javan allied species ... 11 Australian allied species 35 



47 48 



We thus see that while the proportion of the birds derived 

 from each source is almost exactly equal, about three-fourths 

 of those from Java have remained unchanged, while three- 

 fourths of those from Australia have become so modified as 

 to be very distinct species. This shows us how the distribu- 

 tion of birds can, when carefully studied, give us information 

 as to the past history of the earth. 



We can also feel confident that Timor has not been 

 actually connected with Australia, because it has none of the 

 peculiar Australian mammalia, and also because many of the 

 commonest and most widespread groups of Australian birds 

 are entirely wanting. And we are equally certain that 

 Lombok and the islands further east have never been united 

 to Bali and Java, because four Australian or papuan genera 

 of parrots and cockatoos are found in them, but not in Java, 

 as are several species of honeysuckers (Meliphagidae), a 

 family of birds confined to the Australian region. On the 

 other hand, a large number of genera which extend over the 

 whole of the true Malay islands, from Sumatra to Java, never 

 pass the narrow straits into Lombok. Among these are the 

 long-tail parrakeets (Palaeornis), the barbets (Megalaemidae), 

 the weaver-birds (Ploceus), the ground starlings (Sturno- 

 pastor), several genera of woodpeckers, and an immense 

 number of genera of flycatchers, tits, gapers, bulbuls, and 

 other perching birds which abound everywhere in Borneo 

 and Java. 



Two other papers dealt with the parrots and the pigeons 

 of the whole archipelago, and are among the most important 

 of my studies of geographical distribution. That on parrots 

 was written in 1864, and read at a meeting of the Zoological 



