Lepidoptera of Sikkim. 277 
collecting by travellers in tropical countries, as such 
collections rarely contain more than the commoner 
species. I should expect an active and experienced 
collector to take 90 per cent. of the butterflies which 
existed in a district like the Alps or Pyrenees in one 
season, whilst in such a region as Sikkim I do not think 
he would take 50 per cent., though the season lasts at 
least twice aslong. And, notwithstanding the wonderful 
number of butterflies which occur in the lower valleys 
of Sikkim, I have never been able to take in one day so 
many species as 1 have done in one day in the Italian 
valleys of the Alps, whilst in the middle and upper zones 
I should not expect to take more than twenty to thirty 
species of Rhopalocera on the most favourable day, and 
such a day might occur perhaps only half-a-dozen times 
in the whole season. As to the Heterocera, I do not 
believe that a lifetime would exhaust them, as every 
change of locality brings a number of new species, and 
many species only seem to be taken at intervals of 
several years. 
In order to compare the characteristics and abundance 
of the butterfly fauna of Sikkim with that of adjoining 
regions of a similar character, I have selected two of 
which we have the best, though not a complete know- 
ledge ; namely, the Malay Peninsula and the North-west 
Himalayas. 
For the first I have taken Mr. Distant’s catalogue 
of butterflies as it stands in his recently-completed 
work, ‘ Rhopalocera Malayana,’ though I believe that 
if he had worked on such ample materials as I have 
done he would have added many good species to this 
list, and at the same time omitted many which he treats 
as species, though without any proof that they are so. 
For the North-west Himalaya I have compiled a 
catalogue from various sources, of which the principal 
are the lists of Capt. Lang’s collection in Proc. Zool. 
Soc., 1865, and Mr. Hockings, in Proc. Zool. Soc., 1882, 
both worked out by Moore. I have also used the paper 
on the Butterflies of Kumaon by Doherty, in the Journal 
of the Asiatic Society for 1886, and some MSS. notes on 
the Butterflies of Kangra, Kulu, and Lahoul, sent me by 
Capt. Graham Young. As almost all the species de- 
scribed in these papers are well represented in my own 
collection, I am able to say that this list is fairly 
