102 



DISTRIBUTION OF ANIMALS. 



[part I. 



INSECTS. 



The families and genera of insects are so immensely numerous, 

 probably exceeding fifty-fold those of all other land animals, 

 that for this cause alone it would be impossible to enter fully 

 into their distribution. It is also quite unnecessary, because 

 many of the groups are so liable to be transported by accidental 

 causes, that they afford no useful information for our subject ; 

 while others are so obscure and uninteresting that they have 

 been very partially collected and studied, and are for this 

 reason equally ineligible. I have therefore selected a few of 

 the largest and most conspicuous families, which have been so 

 assiduously collected in every part of the globe, and so carefully 

 studied at home, as to afford valuable materials for com- 

 parison with the vertebrate groups, when we have made due 

 allowance for the dependence of many insects on peculiar forms 

 of vegetation, and the facility with which many of them are 

 transported either in the egg, larva, or* perfect state, by winds, 

 currents, and other less known means. 



I confine myself then, almost exclusively, to the sixteen 

 families of Diurnal Lepidoptera or butterflies, and to six of the 

 most extensive, conspicuous, and popular families of Coleoptera. 



