v DISTRIBUTION OF ANIMALS 91 



point of view we are now considering, because it is not 

 exclusively temperate or tropical, but nearly equally divided 

 between the two. It also differs from the Oriental inasmuch 

 as botanists usually claim the flora of the Moluccas and 

 New Guinea as being essentially Malayan, and therefore 

 belonging to the Oriental Region. But the flora of New 

 Guinea has been stated by Sir Joseph Hooker to be so 

 peculiar as almost to deserve to form a Sub-region of its 

 own ; and, till recently, the natural order Dipteraceae, con- 

 sisting of lofty forest-trees with very distinctive botanical 

 characters, was supposed to be limited to the Oriental Region, 

 from the Himalayas to Java, Celebes, and the Philippines. 

 They have, however, now been found both in the Moluccas 

 and New Guinea ; but as westerly winds blow for half the 

 year with great steadiness between Celebes and New Guinea, 

 it is not difficult to explain their presence in the latter country, 

 as their solid but large-winged fruits would be easily drifted 

 for long distances. At all events the extreme richness of 

 New Guinea in both birds and plants, and not improbably in 

 insects also, is a matter of very great interest. 1 



Having shown by the best statistics available that the 

 general phenomena of the numerical distribution of species 

 over small or large areas correspond in their main features 

 for such diverse groups of organisms as plants, insects, and 

 birds, it is quite needless even if it were possible to attempt 

 a similar enumeration for other groups. In reality, with the 

 one exception of land-shells, the materials do not exist for 

 any other organisms. Even the mammalia and reptiles have 

 never been systematically collected in tropical countries, as 

 birds and insects have been collected, and what materials do 

 exist are more difficult to obtain. But to give the general 

 reader some notion of the extent of the whole world of life 

 as now studied by biologists, I will give a tabular statement 

 of the numbers supposed to be actually described, from the 

 estimate made by Mr. Shipley above referred to in the case 

 of insects. 



As regards these figures, I am informed by Mr. R. 



1 For a full explanation of the six great Zoological Regions, here enumerated, 

 the reader is referred to my Geographical Distribution of Animals, vol. i. 

 chap. iv. ; or for a more popular account of them to my Island Life, chap. iii. 



