IV PREFACE. 



of genera and species; whilst the immense number of insect 

 species in hke manner prevented the latter class of works from 

 entering into detailed acconnts of habits and structure, or in- 

 quiries into the relations of the different groups. 



Thus the student was led at once from the general vieivs he 

 had gained of the subject, to the minute technical details of 

 genera and species, there being no work which he could take up 

 to sei've as a guide to the developement of the principles of 

 modern classification, in the disti'ibution of the orders and 

 families. For years this deficiency has strikingly manifested itself 

 to me, and it is long since 1 announced my present undertaking, 

 in which I had proposed to myself to show the application of the 

 modern views which have been entertained relative to the na- 

 tural relations of animals in the arrangement of the entire 

 groups of winged insects; illustrating the subject by details of 

 the natural habits, transformations, and structure of the different 

 families. 



Nothing can be more distinct than the views entertained by 

 Linnaeus and his immediate followers, and modern natia-alists, 

 as to the principles of classification. With the former, nothing 

 further was requisite than the construction of an arrangement 

 by which the name of a species might be arrived at in the most 

 convenient, and, consequently, often in the most artificial, 

 manner. Totally regardless of the relations, more or less re- 

 mote, existing amongst the different groups, their writings cannot 

 be regarded otherwise, than as catalogues raisonnces. Modern 

 entomologists, on the other hand, with Latreille at their head, 

 have endeavoured to render the science more in accordance 

 with nature by the establishment of ^^ Families Naturelles" for the 

 reception of the species most nearly according in habits and 

 structure, the investigation of which, in all the various states of the 

 insects' existence, has been rendered requisite, in order to trace 

 the limits, or to show the points of connexion existing between the 

 different groups. Convinced that in our endeavours to perfect 



