Pulex irritans. 



CHAPTER XIV. 



THE APHANIPTERA, OR FLEAS. 



At the close of the last chapter we saw that whatever 

 apparent contradiction there might be in terms, the 

 existence of such things as Apterous Diptera is by 

 no means impossible. The little insects which I have 

 here placed as forming a distinct order, have also 

 been regarded by many authors as coming under the 

 same denomination, but it seems to me that this is 

 going rather too far, as the Fleas really present very 

 little resemblance to the Diptera, either in their ge- 

 neral organization or in the structure of their mouths. 

 The common Flea {Pulex irritans) , which is pro- 

 bably pretty well known to most of my readers, may 

 serve as an example of this order, which includes but 

 a few species, all of which resemble each other very 

 closely both in structure and habits. This little 

 creature, equally noted for its activity and thirst for 



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