On the Geographical Distribution of Insects. 345 



All these causes, moreover, may be so combined in a certain 

 country, as reciprocally to compensate each other ; while in 

 another they may harmonize in such a way as to produce the 

 highest possible resvdt. It is thus that Africa and equatorial 

 America, though nearly on an equality with respect to tempe- 

 rature, are so differently circumstanced in their insect produc- 

 tions ; the latter being infinitely the richest, because it is ge- 

 nerally more wooded and moist. 



The most general result at which we can arrive, and which 

 is particularly deserving of attention in examining this ques- 

 tion, is that the number of species augments as we recede from 

 the poles and approach the equator. Heat being the most 

 important condition for vegetation, must also be so for insects. 

 But it must not be thence concluded that this increase takes 

 place equally in all countries. The vicinity of Paris, for ex- 

 ample, is as rich in species as that of Marseilles, which is owing 

 to its being more humid, and presenting more varied stations 

 to these animals. 



The law of which we speak, can only be demonstrated, 

 with any degree of precision, in reference to the Coleoptera. 

 and even in their case somewhat imperfectly, owing to the 

 want of local faunas for most countries. With regard to the 

 other orders, we are completely destitute of data for the coun- 

 tries out of Europe, except for a portion of the Lepidojitera. 

 The following table, therefore, relates only to the Coleoptera. 

 An attempt is made to compare with each other only countries 

 of as nearly equal extent as possible ; and it must be remai'ked, 

 in particular, that the portion of Brazil, to which the notice is 

 limited, scarcely equals France in extent. 



Notwithstanding the imperfections of this table, it sufficient- 



