chap. x\i.] INSECTS. 499 



9; and in this respect the Neotropical region agrees with them, 

 though the superiority in the proportion of Cerambycida3 is 

 somewhat less. In the Old World tropical regions, however, 

 and in Australia, the Lamiidae greatly preponderate — being 

 nearly double in the Oriental and Ethiopian regions (or as 11 to 

 6), while in the Australian it is as 6 to 5. The Prionidse show 

 a similar difference, though in a less degree ; being proportion- 

 ately more numerous in the North Temperate and Neotropical 

 regions. Now, as regards the North Temperate regions, this 

 difference can be, to some extent explained, by a difference in 

 the habits of the insects. The Lamiidae, which both in 

 the larva and perfect state have exceedingly powerful jaws, 

 exclusively frequent timber trees, and almost always such as 

 are dead ; while the Cerambycidae, are generally more delicate 

 and have weaker mandibles, and many of the species live on 

 shrubs, dead twigs, foliage, and even on flowers. The immense 

 superiority of the Tropics in the number and variety of their 

 timber trees, and the extent of their forests, sufficiently accounts 

 for their superiority to the Temperate regions in the develop- 

 ment of Lamiidae ; but the great excess of Cerambycidae in 

 South America as compared with the rest of the Tropics, is not 

 to be so readily explained. 



Bearing in mind the different proportions of the families, as 

 above noted, we may now consider the distribution of the 

 Longicorns as a whole. In number of generic forms, the Neo- 

 tropical region, as in so many other groups, has a marked 

 superiority. It possesses 516 genera, 489 of which (or about 

 i|- of the whole) are peculiar to it. The Australian and Orien- 

 tal regions come next, and are exactly equal, both possessing 

 360 genera, and having almost exactly the same proportion (in 

 each case a little less than f ) peculiar. The Ethiopian region 

 has 262 genera, with about £ peculiar ; the Palaearctic 196, with 

 51 (rather more than £) peculiar; and the Nearctic 111, with 

 59 (a little more than half) peculiar. The more isolated of 

 the sub-regions are also well characterised by peculiar genera. 

 Thus, Chili with Temperate South America possesses 37, a 

 large proportion being Cerambycidae; the Malagasi group 26, 



