London Insects. 131 



But as this arrangement, though a little further 

 reaching than the first, gives only three classes, and 

 these with no very clear lines between them, it is not 

 of much more value. For all practical purposes the 

 only possible classification of insects yet worked out 

 is according to the nature of their wings. "Those 

 Hexapod insects," writes Professor Owen the 

 greatest living authority perhaps on all such matters 

 " which are devoid of wings, are called Aptera ; 

 those with two wings only are the Diptera. All the 

 rest have four wings. The Lepidoptera have four scaly 

 wings ; the Hymenoptera have four veined wings, 

 crossing each other when at rest ; the Hemiptera 

 have one pair of wings partially thickened, and 

 called hemelytra ; the Orthorptera have one pair of 

 wings wholly thickened, the other folded length- 

 wise ; the Coleoptera have one pair wholly and much 

 thickened, called elytra, and the other pair folded 

 crosswise ; the Neuroptera have four reticulated wings ; 

 the Strepsiptera have one pair of wings rudimental 

 and curled up. In the Aphaniptera " which, by- 

 the-bye, are not an order by themselves, but only a 

 class of the so-called wingless order " both pairs 

 are rudimental and functionless as wings. Of these 

 orders the first five are ' haustellate ' ; the next four 

 are ' mandibulate.' The Aptera are ' ametabolian ' ; 

 the Hemiptera and Orthoptera are 'hemimetabolian'; 

 the remaining orders are ' metabolian.' " 



" These characters," Professor Owen adds, " briefly 

 and succinctly express the highest generalisations, as 

 yet reached, relative to the Hexapod Insecta." 



But here, as in every attempt of the kind, the more 

 perfect the work the more one is made to feel that 

 classification, absolutely necessary as it is as a step 

 towards progressive knowledge, is at best a purely 



