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PREFACE. 



THE objects that should be kept in view in preparing a Catalogue of 

 Lepidoptera are two in number, both of the greatest possible import- 

 ance. The first is that each species should have a distinctive name by which 

 it can be recognised now, and by which all that has been written about it can 

 be rightly attributed to it. The second object should be to arrange these 

 names in such order, that as far as possible, each species will be surrounded 

 by those to which it is most closely allied. Briefly, the objects should be 

 Correct Nomenclature and Natural Arrangement. 



It has, unfortunately, happened that many species have been described by 

 more than one writer, and different names given by each. It has also 

 happened that the same name has been given by different writers to distinct 

 species. It has thus become necessary for Entomologists to know what 

 species have been described by various writers, and what names have been 

 bestowed upon them, before their past history can be correctly followed. 

 Hence the importance of what are called Synonymic lists or catalogues, in 

 which all the names that have ever been given to the species are placed in 

 chronological order, with the references to the works in which such names are 

 used. In such a list or catalogue the oldest name stands first, and there is 

 a well understood rule among naturalists, called " The Law of Priority," that 

 such oldest name shall be that by which the species is known. Before it can 

 be decided which is the oldest name, it is necessary to ascertain that the dif- 

 ferent authors really meant that particular species, and therefore their figure 

 or description must be examined. To do this is not only a work of very 

 great labour, and requiring great knowledge of different languages, but it 

 also needs an amount of discrimination and judgment that are not the lot of 

 many, and that few possess in equal degree. There has thus arisen a wide 

 diversity of opinion as to the authority that should be given to the works of 

 different authors, and a consequent diversity as to the names by which the 



