46 HOMOPTERA 



In most cases it is of course not necessary to mention all of these characters, but in the instances 

 of closely related genera where careful comparison is required to note differentiation, the entire category 

 is often listed. 



Coloration and sculpturing are in general ignored in these generic descriptions since such char- 

 actersare usually specific rather than generic. 



Neither have we used the genital characters or the abdominal structures, not because these are 

 not valuable, for they probably are, but because they are so extremely difficult to distinguish in mount- 

 ed specimens. 



BIBLIOQRAPHICAL REFERENCES 



For obvious reasons we have abbreviated the bibhographical references to the shortest possible 

 form but we believe that no undue difficulties will be presented because of this fact since we are 

 appending a complete bibUography to which reference may easily be made. 



QEOGRAPHICAL DISTRIBUTION 



It has been our practice for many years to keep a record of all localities represented by specimens 

 sent us for determination as well as of those seen in collections throughout the world. We are thus 

 able to add a great many distribution records to those given in previously published lists. 



The problem has been how to limit the number of references in the cases of widely distributed 

 species. In general, in such cases, we have endeavored to give for each species the general region in 

 which it is to be found, with enough scattered localities to indicate the extent of distribution. 



