vi PEEFACE. 
yet been thoroughly revised, it has not been deemed advisable to make use of 
ths subdivisions at present indicated. Mr. E. Y. Watson's valuable classifi- 
cation of the Hesperiidse has been adopted in this work as far as it goes. 
It is unfortunate, however, that such able work should have been restricted 
to the limited material dealt with. A really comprehensive classification of 
])iurual Lepidoptera, based on sound structural characters, is much needed, 
and would be of the greatest service to Lepidopterists of every country. 
Amongst many Continental entomologists it seems the custom, whenever 
possible, to force every newly discovered species of butterfly occurring within 
Palfearctic limits into one of the genera they are in the habit of using for 
European species, however slight its affinities may be, even though it may 
belong to some well-known Oriental genus ; its habitat would appear to be a 
sufficient reason for denying it its proper position. 
In identifying species there is but one really satisfactory method, and that is 
by comparing them with the actual types. If this is not practicable, reference 
must be made to existing descriptions and figures. The former should be 
not only descriptive, but should also give comparisons with allied species, if 
there are any. Figures are of the greatest use, if accurate, and often save the 
entomologist much time and trouble ; but they can never rank in importance 
with a good description, and some entomologists attach far too much importance 
to them. It often happens that the figure and description are taken from 
diff'erent specimens, and in such cases the former may not quite agree with 
the latter. Sometimes, as has been referred to in this work, an author, who 
especially prides himself on the accuracy of his plates, figures the same unique 
specimen twice with important diff"erences. Mistakes are much more usual 
in hand-coloured plates than in those printed in colours, if well executed. 
If the publication of descriptions of new species were dependent on their 
being accompanied by accurately-coloured figures, the science of Entomology 
would be indefinitely retarded, and the naming of new species restricted to 
