500’ GEOGRAPHICAL ZOOLOGY. [part iy. 
with a preponderance of Lamiidse ; and New Zealand 12, of which 
the Cerambycidse are only slightly in excess. 
The relations between the Longicorn fauna of the several 
regions, are such as are in accordance with the dependence of the 
group on a warm climate and abundant vegetation ; and indicate 
the efficiency of deserts and oceans as barriers to their migration. 
The Neotropical and Australian regions have only 4 genera in 
common, but these are sufficient to show, that there must proba- 
bly once have been some means of communication between the 
two regions, better adapted to these insects than any they now 
possess. The Nearctic and Neotropical regions have 5, and the 
Nearctic and Pal ^arctic 13 genera in common and peculiar to 
them, the latter fact being the most remarkable, because no 
means of inter-communication now exists, except in high lati- 
tudes where the species of the Longicorns are very few. The 
Oriental and Australian regions, on the other hand, are closely 
connected, by having no less than 52 genera of Longicorns in 
common and peculiar to them. Most of these are specially 
characteristic of the Malay Archipelago, often extending over all 
the islands from Sumatra to New Guinea. This large number of 
wide-spread genera of course gives a character of uniformity to 
the entire area over which they extend ; and, with analogous facts 
occurring in other families, has led many entomologists to reject 
that division of the Archipelago between the Australian and 
Oriental regions, which has been so overwhelmingly demon- 
strated to be the natural one in the case of the higher animals. 
The general considerations already advanced in Chapter II. 
enable us, however, to explain such anomalies as this, by the 
great facilities that exist for the transfer from island to island 
of such small animals, so closely connected with woody vege- 
tation in every stage of their existence. That this is the true 
and sufficient explanation, is rendered clear by certain additional 
facts, which those who object to the sharp division of the Indo- 
Malay and Austro-Malay sub-regions have overlooked. 
An analysis of all the Malay Longicorns proves, that besides the 
52 genera characteristic of the Archipelago as a whole, there are 
100 genera which are confined to one or other of its component 
