14 INTRODUCTION 



authors ; in such a case the earliest name is adopted, unless 

 preoccupied by another species in the same genus, and the 

 other names are called synonyms. In this book synonyms are 

 given in brackets after the adopted name ; but only such 

 synonyms are quoted as have been employed in English works 

 still in common use, and it has not been thought worth while to 

 notice the variations of termination introduced by Doublcday. 

 Following the specific name is given (in abbreviated form) the 

 name of the author who first bestowed it ; this, though not 

 necessary, is often convenient, as the same name has been not 

 unfrequently used by different authors to apply to different 

 insects. 



The genera are associated together to form families, all of 

 whose titles have the termination -idae or -adae. Similarly 

 the families are associated together in groups, whose titles have 

 the termination -ina. Occasionally it is found convenient to 

 subdivide a family into sub-families, whose titles have the 

 termination -ides or -odes. 



Mi I hod of Description. 



A species will be most quickly identified by means of the 

 complete system of analytical keys supplied ; following the 

 definition of the order will be found a key to the groups, under 

 each group a key to the families contained in it, under each 

 family a key to the genera, and under each genus a key to the 

 species ; these four stages include the whole process. Every 

 key is dichotomous throughout, that is, each head is subdivided 

 into two until the final results are reached. Each head is 

 numbered consecutively, and each subdivision of a head is made 

 to refer either to a final result or to a following head. Thus, in 

 the tabulation of groups, under the first head, we have to decide 

 whether the species under examination has more than six veins 

 rising from the cell of the hindwings ; if it has, it is at once 

 referred to the Microptcrygina, to which we should turn for the 

 next tabulation ; if not, it is referred to the number 2, meaning 

 the second head, of which the subdivision proceeds in the same 

 way. Care has been taken to make these tabulations as accurate 

 as possible, but they are necessarily based in general on single 

 characters, and should be regarded as affording probable in- 

 dications only, the full description being always consulted for 

 complete verification. 



The descriptions of groups, families, genera, and species, are 

 framed with a view to conciseness, and do not claim to be com- 



