CO 
rNTRODl'CTION. 
difficulties formerly alluded to, and partly to the 
vast extent of the subject. Let any one attempt to 
arrange and name a moderate sized collection of fo- 
reign moths, and he -will soon be convinced how little 
has been done to facilitate his labours. The system 
of Latreille, one of the few that professes to apply 
to the whole subject, may now be regarded as little 
more than an outline, which leaves a great mass of 
the species altogether unprovided for. Hence the 
necessity that continually arises, even when giving 
the history of a comparatively limited number of 
species, for the establishment of many new genera. 
It must be admitted that such a step, in regard to 
insulated species, and when there is no means of 
distinctly pointing out the limits and relations of 
the genus so constituted, is in some degree unsatis- 
factory; and it becomes even more so when the 
genus is formed, as is sometimes necessarily the 
case, from the mere inspection of an engraved figure, 
destitute of those details of structure which should 
enter into the generic definition. But when it is 
found that the insect thus distinguished cannot with 
propriety be included in any of the existing genera ; 
that it affords prima facie grounds of distinction 
which cannot be overlooked, there is no alternative 
but to adopt this course. It is at least advancing 
on the right path, although the progress may not 
be so considerable as might be desired. 
There are few departments of entomology more 
worthy of the attention of travellers in foreign coun- 
tries than that now under consideration. Scarcely 
