164 THE MALAYAN PAPILIONIDE 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 Linnzan 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- 
