SEPTENARY SYSTEM. 239 



and Perla is readily traced, by means of this genus and the 

 genuine Termites. In many of the Psocl the mouth undergoes 

 a complete change, the component parts become linear and 

 rigid. By this character, as well as the narrow prothorax, 

 increasing mesothorax, and often folded hind wings, we are 

 prepared for the obsolete mouth, obsolete prothorax, fully deve- 

 loped mesothorax and folded hind wings, which characterise 

 the Stirps Phryganina. The circle is here complete ; from the 

 Phryganina to the Ephemerina, the transition is perfectly 

 natural. 



I am well aware how very little this tends to the corrobora- 

 tion of any system. I am as unable as my readers to see any 

 striking relation between these groups and the classes to which 

 I suppose they lead. All that I assert is, that, attending 

 solely to structure and metamorphosis, the foregoing appears a 

 natural arrangement of the principal groups into which 

 Neuroptera may be divided. It possesses points which indi- 

 cate the truth of a septenary arrangement, an assertion that we 

 shall see exemplified as we proceed. To myself these gradual 

 indications appear of paramount importance. An insect may 

 hereafter be met with which shall possess the hind wings of 

 Neuroptera, with a pair of rudimental or protecting fore wings ; 

 the prothorax may be that of Coleoptera, the head and mouth 

 those of Mantispa or Raphidia. These peculiarities, coupled 

 with the relations shown above, would render such a genus 

 invaluable ; without them it would be a mere stumbling-block, 

 like Stylops and Atractocerus. 



The supposed position of the classes surrounding Neurop- 

 tera may be seen by the diagram. 



The arguments on which the proposed position of the seven 

 classes was defended, were drawn up with scarcely a reference 

 to those important characters on which natural arrangement 

 essentially depends. On more attentively considering the 

 subject, I found that the exact points of union between neigh- 

 bouring classes was a subject of very limited importance, while 

 the approximating location of great groups was the grand object 

 to achieve. With this view I determined to learn before again 

 attempting to teach. I sought out, and, I think I may say, 

 mastered every arrangement of insects that has been transmitted 

 to us. When we look back at our predecessors in Entomology ; 

 when we consult the works of Aristotle, Linneus, Fabricius, 



