PREFACE TO THE PRESENT 

 EDITION. 



A NEW edition of this volume having become necessary, it was 

 deemed a fitting opportunity to bring the subject matter some- 

 what in Hne 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. Pleris 

 dnplidice of the ist edition becomes in the present one Pontia 

 {Picris) 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. 



