478 



Mr. A. R. Wallace on the Natural History 



One duck, near Anas radjah, Less. 

 Twelve pigeons, Alecthelia Urvillei, 

 Less. 



New Guinea species. 

 Three New Guinea species. 

 Six Ptilotis. 

 Both New Guinea species. 



Two New Guinea species. 

 Both New Guinea species. 



A New Guinea species. 



Four or five New Guinea species. 



EurystomuSj same at Macassar 



and Lombock. 

 One New Guinea, one Australian. 

 Podargus and Caprimulgus. 

 Four or five New Guinea species.' 

 Centropits and Chrysococcijx. 



From this list, and the preceding observations, it will be seen 

 that many Australian genera and some species occur in Aru ; 

 while, considering the very small number of species known from 

 New Guinea, and the necessarily very imperfect exploration of 

 Aru in such a short time, the number of identical species is very 

 remarkable. I believe that nearly one-half of the hitherto-de- 

 scribed species of passerine birds from New Guinea will be 

 found in my Aru collections, a proportion which we could only 

 expect if all the species of the latter country inhabit also the 

 former. Such an identity occurs, I believe, in no other countries 

 separated by so wide an interval of sea, for the average distance 

 of the coast of Aru from that of New Guinea is at least ] 50 miles, 

 and the points of nearest approach upwards of 100. Ceylon is 

 nearer to India ; Van Diemen's Land is not farther from Au- 

 stralia, nor Sardinia from Italy ; yet all these countries present 

 differences more or less marked in their faunas ; they possess 

 each their peculiar species, and sometimes even peculiar genera. 

 Almost the only islands possessing a rich fauna, but identical 

 with that of the adjacent continent, are Great Britain and Sicily, 

 and that circumstance is held to prove that they have been once 



