164 THE MALAYAN PAPILIONID& AS 



general conclusion is entirely objected to by the writer 

 of the article in the " Natural History Review," who, 

 however, does not deny its applicability to the par- 

 ticular order under discussion, while this very differ- 

 ence of opinion is another proof that difficulties in 

 the determination of species do not, any more than 

 in the higher groups, vanish with increasing mate- 

 rials and more accurate research. 



Another striking example of the same kind is seen 

 in the genera Rubus and Rosa, adduced by Mr. 

 Darwin himself; for though the amplest materials 

 exist for a knowledge of these groups, and the most 

 careful research has been bestowed upon them, yet 

 the various species have not thereby been accurately 

 limited and defined so as to satisfy the majority of 

 botanists. In Mr. Baker's revision of the British 

 Roses, just published by the Linnsean Society, the 

 author includes under the single species Rosa canina, 

 no less than twenty-eight named varieties, distin- 

 guished by more or less constant characters and often 

 confined to special localities ; and to these are referred 

 about seventy of the species of Continental and British 

 botanists. 



Dr. Hooker seems to have found the same thing 

 in his study of the Arctic flora. For though he has 

 had much of the accumulated materials of his pre- 

 decessors to work upon, he continually expresses him- 

 self as unable to do more than group the numerous 

 and apparently fluctuating forms into more or less im- 

 perfectly defined species. In his paper on the "Dis- 



