174 INSECTS 



4. Platyptera. Four net-veined wings ; nioutli parts adapted for biting 



( = Termitidae and Mallophagu, 23arts of our Neuroptera). 



5. Odonata. Wings net -veined, equal (= Odonata, a division of our 



Neuroptera). 



6. Plectoplera. Wings net-veined, unequal ( = Ephemeridae, a part of our 



Neuropitera). 



7. Tlnjsanoptera. Mouth beaklike but witli palpi ( = our Thysanoptera). 



8. Hemiptera. Mouth parts forming a beak for suclfing. No palpi ( = our 



Hemiptera). 



The above eight Orders form the group Ametabola, while the 

 following eight constitute the Metabola : — 



9. Neuroptera. Wings net- veined ; metamorphosis complete ( = a small part 



of our Neuroptera). 



10. Mecaptera. Wings long and narrow (for a small j)art of our Neuroptera; 



the Panorpatae of Brauer). 



11. Trichoptera. Wings not net-veined ( = our division of Neuroptera with 



the same name). 



1 2. Goleoptera. Fore wings sheathing the hinder ones ( = our Coleop>tera). 



1 3. Siplionaptera. Wingless, parasitic. Flea ( = a division of Diptera). 



14. Diptera. One pair of wings ( = our Diptera after subtraction of 



Siphonap>lerci). 



15. Lepidoptera. Four wings (and bodj') scaled ( = our Lepidoptera). 



1 6. Hymenojitera. Four clear wings ; hinder pair small ; a tongue ( = our 



Hyrtienoptera). 



Although this system of the Orders of Insects has some 

 valuable featiu-es it is open to very serious objections, to which we 

 can only briefly allude. The Order Hemiptera with its extensive 

 divisions, Heteroptera, Homoptera, Coccidae, and Anoplura exhibit- 

 ing great differences in structure and considerable divergence in 

 metamorphosis, is treated as only equivalent to the little group 

 Panorpatae (scorpion-flies) ; these latter being considered a dis- 

 tinct order, although they are not very different in structure or 

 metamorphosis from the Orders he calls iS^europtera and Trichop- 

 tera. The arrangement appears to be specially designed with 

 the view of making the Orders adopted in it fall into the two 

 groups Ametabola and Metabola. The propriety of such a 

 course is more than doubtful since very few of the Ametabola 

 are really without metamorphosis, in the wide sense of that term, 

 while the Metabola include Insects with various kinds of meta- 

 morphosis. Indeed if we sul3stitute for the term Ametabola the 

 more correct expression, " Insects with little metamorphosis," and 

 for Metabola the definition, " Insects with more metamorphosis 

 but of various kinds," we then recognise that the arrangement 



