84 



CHAPTER VIII. 



OF THE CLASS OF INSECTS. 



602. THE class of Insects is pre-eminent, not only amongst 

 the divisions of the Articulated series, but in the whole Animal 

 kingdom, in regard to the number of distinct species which it 

 includes ; and it is probably unsurpassed by any, save the Infu- 

 sory Animalcules, in regard to the number of individuals at any 

 time existing on the earth's surface, which belong to the nu- 

 merous and diversified races comprehended in it. The whole 

 sub-kingdom of Vertebrated animals may probably be estimated 

 as not containing above 30,000 species, a number which is 

 surpassed by the Beetle tribe alone ; and we should be probably 

 not far wrong in saying, that the number of species of the whole 

 class, already known, exceeds that of all other animals put toge- 

 ther. Moreover, on account of the small size of all, and the very 

 minute size of a large proportion, of the animals belonging to 

 this class, it is probable that the number of species already 

 known is far surpassed by that which remains to be discovered. 

 Even in our own country, new species of Insects are continually 

 being discovered, by the industry of observers who devote 

 themselves to this particular branch ; and the number at present 

 unknown must of course be far greater, in countries that have 

 been less completely explored. Of the importance of this class 

 in the economy of Nature, several striking proofs will be given 

 hereafter. 



603. The tegumentary skeleton of Insects, that is to say, 

 the hard skin of these animals, sometimes preserves a certain 

 degree of flexibility ; but generally presents a consistency analo- 

 gous to that of horn. It must not be thought, however, that its 

 tissue is really of that nature ; for Chemistry teaches us that it 

 is composed of very different materials, and that a particular 



