in Zoological and Botanical Geography. 9 



region (which its great richness in peculiar generic forms 

 seems to indicate), we can easily understand how, when the 

 islands of the Moluccas and New Guinea first rose above 

 the waters and became clothed with dense forests nurtured 

 by tropical heat and perpetual moisture, thougli the birds 

 and mammals readily adapted themselves to the new con- 

 ditions, the insects could not do so, but gave way before the 

 immigrants from the islands to the west of them, whicli 

 having been developed under similar climatal conditions, 

 and thus become specially adapted to them, were enabled, 

 by the enormous powers of multiplication and dispersion 

 possessed by insects, at once to establish themselves in the 

 newly-formed lands, and develop an insect population in 

 many respects at variance with other classes of animals. 



There are, however, several instances of groups of insects 

 almost as strictly confined to one-half of the Archipelago as 

 is so remarkably the case with the vertebrata ; and when 

 the extensive collections made by myself in most of the 

 islands come to be accurately worked out, no doubt more 

 such -instances will be found. Among Coleoptera I may 

 mention the Tmesisternince, a remarkable sub-family of 

 Longicornes, as being strictly confined to the Australian 

 region, over the whole of which it extends, and has its 

 western limit in Celebes along with the Marsupials and the 

 Trichoglossi. Again, Mr Baly, so well known for his 

 acquaintance with the Phytophagous Coleoptera, finds that 

 one of the principal sub-families of that tribe (Adoxinse), 

 which he has recently classified, though spread over Europe 

 and the whole of Asia, is only found in the Archipelago in 

 those islands which belong to the Indian region of zoology. 

 This proves that there is an ancient insect-population in the 

 Austro-Malayan Islands, which accords in its distribution 

 with the other classes of animals, but which has been over- 

 whelmed, and in some cases perhaps exterminated, by im- 

 migrants from the adjacent countries. The result is a 

 mixture of races, in which the foreign element is in excess ; 

 but naturalists need not be bound by the same rule as poli- 

 ticians, and may be permitted to recognise the just claims 

 of the more ancient inhabitants, and to raise up fallen 

 nationalities. The aborigines, and not the invaders, must 



NEW SERIES." VOL. XIX. NO. I.-- JANUARY 1864. B 



