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Fresh-water Biology 



Recognition Characters of Some of the Commoner 



Single distinctive characters 



1. Forms in which the immature stages (commonly known as nymphs) are not 

 visible upon the back. 



2. Forms in which the immature stages differ very greatly from the adults of the same 

 from the outside, and having the legs shorter, rudimentary, or even wanting {larvae 



3. Further characters of some common dipterous larvae: these are distinguished from 



