582 



FOURTH SECTION. 



TAXONOMY. 



FIRST CHAPTER. 



GENERAL IDEAS. 



318. 



TAXONOMV, which is the last division of the general portion of 



Entomology, has to exhibit the means whereby the large host of insects 



may, according to certain principles, be classed in divisions and groups, 



and also the connexion of these groups together. The necessity of this 



grouping and subdivision is not so evident in any class of animals as 



the present, as the number of their different forms is very great, and 



doubtlessly greater than those of the entire vegetable kingdom. A 



computation of the known species has not been indeed latterly made, 



and can scarcely be so, as all the known forms are nowhere yet brought 



together, or even described, yet a tolerable result may be deduced by 



comparing the number of known species of any country with its 



indigenous plants, and then forming a comparative computation with 



that of all known plants. There are, for instance, in Germany, 



including the Cryptogamea, at most 6000 different plants, but certainly 



more than 12,000 insects, so that if this proportion be constant, which 



may be admitted, the number of known insects, according to the 



6070,000 known plants, will evidently rise to 120 140,000 species. 



If, now, in concordance with the estimation of the latest and most 



successful botanists, we say that about one-third of the collective species 



of plants are known, then the number of insects inhabiting the earth 



would amount to from 360 420,000 species, or, in round numbers, we 



may say 400,000. But this number has neither been collected nor 



described. Even were we to calculate all that are preserved in the large 



