A new edition of this volume having become necessary, it was deemed a
fitting opportunity to bring the subject matter somewhat in line with our
present knowledge of the Nomenclature, Habits, and Distribution of the
Species considered therein. With this end in view, the new facts have been
incorporated in the text so far as this was possible. Matter that could not
be accommodated in this way has been presented in the form of an Appendix.
The changes in the names of genera are not numerous, and in every case
where such change has been made, the name used in the first edition has
been placed in brackets--_i.e._ _Pieris daplidice_ of the 1st edition
becomes in the present one _Pontia (Pieris) daplidice_.
By this treatment it has been found convenient to utilise the old Index
and, at the same time, to provide a Specific Index for those who prefer to
consult the volume by its aid.
* * * * *
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