INTRODUCTION. ix 



Wings with a few principal vein.-, ; nu;taniorpliorsi.s perfect, pupa inactive; 



iarva mandil)ulate. 2. 



Wingri variable; mctaniorjjluwis imperfe(-t, pupa active; larva and imago 



haustellate. 7. 



Wings with numerous veins ; pupa variable ; larva and imago niandibu- 



late. 8. 



Wings wanting ; metamorphosis none ; thoracic segments similar. ?>. 



2. Thorax agglutinate. 3. 

 Prothorax free. (j. 



3. Mouth mandibulate. 4, 

 Mouth haustellate. ',, 



4. Four membranous wings fitted for flight. Hymenopteea. 



5. Hind wings abortive. Dipteka. 

 Four broad wings clothed with scales. Lepjdopteka. 



6. Prothorax free, front wings not suited for flight. Coleopteka. 



7. Front wings partly coriaceous, hind pair with but few veins ; prothorax 



large, free, as in Coleoptera. (Hetekopteka) Hemiptera. 



Wings membranous, with numerous veins. Homoptera. 



8. .Prothorax fi-ee, front wings unfitted for flight; hind wings folded like 



a fan. Okthoptera. 



Thorax variable, wings not folded, membranous, fitted for flight.* 



Neuroptera. 



0. Abdomen without appendages ; mouth mandil)ulate, excei)t in Pedi- 



culidffi ; (habits epizootic). Anoplura. 



Abdomen with anal appinidages ; mouth mandibulate ; body elothe<l 



with scales, like those of the wings of Lepidoptera. Tiiysanura. 



The order Neuroptera is diffieult to define, tlioiigh the sul)- 

 orders composing it arc very readily distinguished from any of 

 the other orders. 



Of these orders the first three constitute the division Metaboia 

 Scudder. They are tlie higliest type of insects, and are charac- 

 terized hy agglutinate thorax (protliorax very small and not free), 

 membranous wings with few veins, the anterior pair being the 

 larger; and by perfect metamorphosis. 



The otlier orders are grouped as Heterometabola, and tlio 

 sequence in the table above given indicates the gradiuil dcgrada- 



* Those having an active pupa (Biomorphotica Wcstwood) are now called 

 Psoudoneuroptera, and have been united by some authors with Ortboptera, 

 with which, however, they appear to have but little affinity. The habits, 

 as observed to us by Baron R. Ogten Sacken, are quite different, tlie 

 Orthoptera being terrestrial, using tlusir wings only as accessories in pro- 

 gression, while the Pseudoneuroptera are essentially aerial, passing the 

 greater part of the time on the wing. 



