1/4 INSECTS CHAP. 



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



( = Termitidae and Mallophaga, parts of our Neuroptera). 



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



Neuroptera). 



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



Neuroptera). 



7. Thysanoptera. Mouth beaklike but with palpi ( = our Thysanopteni). 



8. Hemiptera. Mouth parts forming a beak for sucking. 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 (fora small part of our Neuroptera; 



the Panorpatae of Brauer). 



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



the same name). 



1 2. Coleoptera. Fore wings sheathing the hinder ones ( = our Coleoptera). 



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



1 4. Diptera. One pair of wings ( = our Diptera after subtraction of 



Siphonaplent). 



15. Lepidoptera. Four wings (and body) scaled ( = our Lepidoptera). 



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



Hymenoptera). 



Although this system of the Orders of Insects has some 

 valuable features 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 Neuroptera 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 substitute 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 



