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 place Entomology 

 in this respect by the side of her more fortunate sister : 

 and subsequently Mr. Vf. 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 Mus. 1815, b Hor. Entomolog. 42. 518, 



