INTRODUCTION. 



In describing several new species of Tortricidce from North America, and re- 

 describing such of Mr. Walker's species as had not been anticipated by other 

 authors, and of which the types are now in the British Museum, I have thought 

 it advisable to adopt as far as possible the system of classification laid down by 

 Heinemann in his ' Schmetterlinge Deutschlands und der Schweiz,' published 

 in 1865. 



Many systems of generic subdivision have been suggested for this difficult 

 group ; but all appear to have been founded upon a study of European species 

 only. So far as I have been able to judge, none of these various systems are 

 sufficiently perfect and natural to facilitate the arrangement of a cosmopolitan 

 collection. It is very desirable that some comprehensive system should be 

 devised ; but for this purpose a very careful study of specimens from all parts 

 of the world is obviously necessary, and it may be long before such a work can 

 be successfully undertaken. Until this has been done, any arrangement of this 

 group of insects must, I think, be considered, in part at least, provisional. 



In the meanwhile Heinemann's system, although not infallible when applied 

 to large numbers of species with which he was necessarily unacquainted, seems 

 to afford a wider and sounder basis for generic classification than those of other 

 authors. He attaches much value to differences of neuration; and although 



