8 Methods of Investigation. 



themselves would be practically useless. But all the 

 species can be distinguished without difficulty by means 

 of their galls, and these have beerf drawn as faithfully 

 as possible from fresh typical examples. The galls of 

 associated generations have been marked in the plates 

 by the same number, the generation occurring only in 

 the female sex being marked thus, ' i,' and that in 

 which both sexes occur thus, ' i^ '. 



For greater convenience of reference, I have 

 arranged the species in the following groups : — 



I. Neuroterus. 

 II. Aphilotrix. 



III. Dryophanta. 



IV. BlORHIZA. 



