8 Mr Alfred K. Wallace on some Anomalies 



Tt would seem, therefore, that the supposed discrepancy 

 of the Mammalia, in determining the southern limit of the 

 Palaearctic province, is altogether imaginary. The number 

 of species absolutely identical is not so great as in the birds ; 

 but Europe is not the whole Palsearctic province, and if we 

 take genera instead of species, we shall find the correspond- 

 ence as complete as possible, — twenty-eight genera being 

 truly Palsearctic, only three Ethiopian, while five are Asia- 

 tic, or desert-dwellers. In this case, therefore, the whole of 

 the vertebrata combine with the insects, the land shells, 

 and the plants, to place North Africa in the Palsearctic 

 region. 



The case of the insects in the Australian portion of the 

 Malay Archipelago is one of much greater difficulty. Austra- 

 lia itself contains a remarkable assemblage of insects, among 

 which its Lamellicornes, Buprestidse, and Curculionidse offer 

 a number of striking forms and genera quite peculiar to it. 

 In New Guinea and the Moluccas, on the other hand, Lamel- 

 licornes are comparatively scarce, and with the Buprestidse 

 and Curculionidse are of Indian rather than Australian 

 genera ; while the great family of the Anthribidse, which is 

 almost entirely absent in Australia, is here everywhere 

 abundant in genera, species and individuals, though less so 

 than in the Western or Indian region. 



To account for this remarkable discrepancy, we must 

 consider, — 1st, That insects are much more immediately 

 dependent on the character of the vegetation, and therefore 

 on climate, than are vertebrated animals ; and, 2dly, That 

 water-barriers are much less effective in preventing their 

 dispersion. A narrow strait is an effectual bar to the mi- 

 gration of mammals and of many reptiles and birds, while 

 insects may be transported in the egg and larva state by 

 floating timber, and from their small size and great powers 

 of flight, may be easily carried by the winds from one island 

 to another. Now, the characteristic insects of Australia 

 seem specially adapted to a dry climate and a shrubby 

 flower-bearing vegetation, and could hardly exist in the 

 excessively moist atmosphere and amid the dense flowerless 

 forests of the equatorial islands. If, therefore, we suppose 

 Australia itself to be the most ancient portion of this 



