6 



The Naturalist. 



Leaving now the classification according to the pupae, we turn to 

 that of arrangement by the affinities of the imago ; and while I would 

 not take any one stage of the existence upon which to base a classifica- 

 tion, but take the whole life- history into consideration, yet the imago 

 should rank as of first importance, because we know most about that 

 state ; and it is in that state in which insects are generally arranged 

 for public examination. 



The first classification based upon characters of the imago is that of 

 Linnaeus, and is founded upon the characters of the wings. His first 

 division is, those having four wings ; the next, those with two wings ; 

 and the third, those destitute of wings — which results in the following 

 distribution of the different orders : — ■ 



1. Coleoptera 5. Hymenoptera 



2. Hemiptera 6. Diptera 



3. Lepidoptera 7. Aptera 



4. Neuroptera 



After this came the system of Fabricius, founded mainly upon tlie 

 characters of the mouth part, but when we see that it resulted in the 

 crabs and lobsters being placed between the Neuroptera and the 

 Lepidoptera, we may venture to dismiss it as unsuitable, at least for 

 our present purposes. 



We now come to the system of Olivier, in which the characters of 

 both wings and mouth are used as a means of classification, which 

 resulted in the following arrangement : — 



1. Thysanura 7. Hemiptera 



2. Parasita 8. Neuroptera 



3. Siphonaptera (fleas) 9. Hymenoptera 



4. Coleoptera 10. Lepidoptera 



5. Dermaptera (earwigs.) 11. Rhipiptera (bee parasites.) 



6. Orthoptera 12. Diptera. 



The objection to this system is that it separates the Coleoptera and 

 Orthoptera, which have both mandibulate mouths, and which are in 

 other respects nearly allied. The Parasita, Hemiptera, Neuroptera, 

 and Lepidoptera have also each two distinct classes of mouth organs. 



At present I cannot but regard the characters of the mouth as 

 insufficient for the distribution of the British insects into orders, 

 although up to the time of Stephens, and in some instances up to the 

 present, this mode of classification has been mainly adopted. In many 

 of the various orders do we find both the haustellate and mandibulate 

 characters, and if this rule be rigidly adhered to, it will result in the 

 lepidopterous insects being placed in one division, while the larvae 



