570 INVESTIGATION OF INSECTS. 



their habitat and localities, or the source from which you 

 derived them. In this you should number the genera in 

 Roman capitals, and the species under each by a figure; 

 leaving considerable space at the end of each genus for 

 the insertion of new species. The other book should be 

 of an octavo size, containing 400 or 500 pages. Under 

 the number of each genus and species you might de- 

 scribe and figure it, if undescribed ; if described, note in 

 what it varies from the description, and what characters 

 are overlooked: and in general, insert such observations, 

 with regard to its economy and habits, as you may have 

 had an opportunity of making. As to foreign insects? 

 wherever you can, upon good authority, be particular in 

 indicating the country and station of each specimen. 



I need not say much to you concerning the micro- 

 scopes you should use for the examination of insects, a 

 common pocket one of three glasses of different powers 

 will answer every ordinary purpose 3 . 



We have treated hitherto of insects as we find them 

 now inhabiting our globe : but I must not conclude our 

 correspondence without taking some notice of those that 

 are found in & fossil state. Fossil insects may be divided 

 into those that are found in amber, and those that are 

 found in other substances. 



It has been observed with respect to insectiferous am- 

 ber, that the greater part of the insects found in it exist 

 no longer in the countries that produce that amber, and 

 that in every different locality the insects found in it are 



a For dissections the one recommended above, p. 201, may be 

 used. Sometimes a watchmaker's eye-glass, which also sets the hands 

 at liberty, will be found useful. 



