4-88 GEOGRAPHICAL DISTRIBUTION OF INSECTS. 
any improvement or enlargement of this last department 
was attempted; when in 1815 M. Latreille, stimulated 
by what had been effected in Botany, in a learned and 
admirable memoir a endeavoured to rrtace Entomology 
in this respect by the side of* her more fortunate sister : 
and subsequently Mr. W. S. MacLeay, in the memora- 
ble work so often quoted in our correspondence, has 
viewed the subject in another light, and added some 
important information to what had been before col- 
lected b . 
The point now under consideration naturally divides 
itself into two principal branches ; — the numerical distri- 
bution of insects, and the topographical. 
I. By the numerical distribution of insects I mean 
not only the number which Providence has employed 
to carry on its great plan on this terraqueous globe, or 
any given portion of it ; or of the species of which each 
group or genus may be supposed to consist ; or of the 
comparative number of individuals furnished by each 
species, — points of no easy solution : but more parti- 
cularly their distribution according to their functions, 
whether they prey upon animal or vegetable matter, and 
in its living or decaying state. 
We have no data enabling us to ascertain with any 
degree of accuracy the actual number of species of in- 
sects and Arachnida distributed over the surface of the 
globe ; but it is doubtless regulated in a great degree by 
that of plants. We should first then endeavour to gain 
some just though general notion on that head. Now 
Decandolle conjectures that the number of the species 
a Mem. du Mm. 1815. b Hor. Entomolos. 42—. 518. 
