DISTRIBUTION OF INSECTS INTO ORDERS. 23 



views opened to them by the researches of comparative anatomists, 

 that it was necessary to have recourse to the entire characters 

 afforded by the insect in all its stages, and with reference also to its 

 internal as well as external organization. Here, however, we are 

 met, as might indeed be naturally expected, by difficulties of a far 

 greater weight than were caused by the employment of a single 

 character in its various modifications ; since a very slight acquaintance 

 with any extensive group of insects will be sufficient to prove, that 

 many characters which we find in one group, exhibiting a constancy 

 of character, vary in the greatest degree in another, showing that 

 although with the former they might, and indeed ought to be re- 

 garded of the highest importance, in the latter they acquire but a 

 secondary consideration ; thus, whilst some groups which agree in 

 their wings, disagree in the structure of the mouth ; others agree- 

 ing in metamorphosis, vary in their organs of flight. 



The first attempts made towards the establishment of this, which has 

 been called, the Eclectic System, were of course partial ; thus Olivier, in 

 1789, proposed a system in which insects were divided into eight 

 orders, distributed primarily from the wings, from which, as well as, 

 secondly from the mouth, the characters of the orders were derived. 

 Clairville on the contrary, in 1798, divided the winged insects into 

 two groups, Mandibulata and Haustellata, from the structure of the 

 mouth, whether furnished with jaws or a proboscis, characterising 

 the orders from the wings. But it is to Latreille that we are indebted 

 for the great advances made towards the perfection of this system. 

 For nearly forty years was this author unceasingly occupied in im- 

 proving the classification of insects ; and it was by him that the 

 introduction of family groups was effected, from which so great ad- 

 vantages were derived, by greatly limiting the number of the secondary 

 groups ; which from the cutting up of the more unwieldy Linna^an 

 genera had become very numei'ous. It is true that his numerous suc- 

 cessive publications exhibit variations in the classification of some of 

 the orders ; but this was the natural result of his labours, which were 

 closed by the publication of his introductory work, the Cours dEnto- 

 mologie, in which the Hexapod Annulosa formed his fourth Class 

 Insecta, distributed as follows : — 



c 4 



