1*20 ON THE OBJECTS OF A COLLECTION OF INSECTS. 



Agrarian species, which in every case is most familiar, 

 abounds on the ascent and especially in the valleys." This 

 is not the place to investigate the question, but I have 

 indicated it as one which can only be decided by a careful 

 examination of a series of specimens judiciously collected. 



Mr. Wollaston in his excellent work, which cannot be 

 too highly praised, on the Insects of Madeira, informs us, 

 that out of four hundred and eighty-two species of Coleop- 

 tera occurring in that group of islands, two hundred and one 

 are also found in Europe. To account for this we must 

 suppose one of two things, either that the two hundred and 

 one species of insects have been introduced by accident, as by 

 man or by winds, or some similar cause ; or else that these 

 species have been in existence ever since the time when 

 Madeira formed part of the great continent. The latter 

 supposition will certainly be preferred by all who have 

 studied the great changes which have taken place in the 

 distribution of sea and land even in the most recent geolo- 

 gical period. 



Similar reasoning will hereafter afford us curious evidence 

 of the relative antiquity of different species and of former 

 geography, but it is extremely difficult and must be used with 

 the greatest caution. 



For if the immense number of the species of insects has 

 hitherto prevented Entomology from bearing much fruit of 

 this nature, it, on the other hand, holds out the promise of 

 an abundant harvest in future ; and, when we shall have cor- 

 rect and complete lists of the insects of different countries, 

 the results cannot fail to be extremely interesting. 



The collections of insects now being formed are great 

 storehouses of facts, which ere long some future Humboldt 

 or Edward Forbes will turn to good account, and from which 

 he will perhaps draw conclusions, the nature of which we 

 cannot at present conjecture. 



