GEOGRAPHICAL DISTRIBUTION OF INSECTS. 489 



of plants, 60,000 being already known, may be some- 

 where between 110,000 and 120,000 a . If we consider 

 with reference to this calculation, that though the great 

 body of the mosses, lichens, and sea-weeds are exempt 

 from the attack of insects, yet as avast number of phanero- 

 gamous plants and fungi are inhabited by several species, 

 we may form some idea how immense must be the num- 

 ber of existing insects; and how beggarly does Ray's con- 

 jecture of 20,000 species , which in his time was reckoned 

 a magnificent idea, appear in comparison ! Perhaps we 

 may obtain some approximation by comparing the num- 

 ber of the species of insects already discovered in Britain 

 with that of its phanerogamous plants. The latter, and it 

 is not to be expected that any large number of species have 

 escaped the researches of our numerous Botanists, may 

 be stated in round numbers at 1500, while the British in- 

 sects, (and thousands it is probable remain still undisco- 

 vered,) amount to 10,000 ; which is more than six insects 

 to one plant. Now though this proportion, it is probable, 

 does not hold universally ; yet if it be considered how 

 much more prolific in species tropical regions are than 

 our chilly climate, it may perhaps be regarded as not 

 very wide of a fair medium. If then we reckon the pha- 

 nerogamous vegetables of the globe in round numbers at 

 100,000 species, the number of insects would amount to 

 600,000. If we say 400,000, we shall perhaps not be 

 very wide of the tfuth. When we reflect how much 

 greater attention has been paid to the collection of 

 plants than to that of insects, and that 100,000 species 

 of the latter may be supposed already to have a place 



a Essai Element, de Geograph. Botan. 62. 

 b Wisdom of God, &r. 2d edit. 9. 



