196 ; _. THE ENTOMOLOGIST. 
bution, as hitherto, constituted the pivot upon which I based 
‘my observations and particular line of inquiry. Although the 
Himalayas, according to geographers in, general, consist of five 
‘principal parallel chains or ranges, two of which are situated 
upon the plateau of Thibet, for zoological and botanical purposes 
they are usually considered as including only that particular 
portion known as the central or meridional ridge, on the austral 
or Indian side of the high Asiatic tableland, together with its 
numerous spurs and continuations to the south. On the extreme 
western side the range is bounded by the Indus, where it makes 
a sudden bend and debouches into the plain, while on the east it 
terminates at the romantic gorge of the Brahmaputra or Tsangpo. 
Within these well-defined limits, which extend for about fifteen 
hundred miles in length and vary from one hundred to two 
hundred miles in width, the number of species of Rhopalocera 
possibly falls not far short of one thousand. Of this number, 
indeed, nearly six hundred and fifty different species have already 
been recorded from Sikkim and Western Bhutan alone, as many 
as six hundred and thirty-one having been particularised in the 
admirable ‘‘ List of the Butterflies of Sikkim,” by the late Lionel 
de Nicéville, in the ‘ Gazetteer of Sikkim,’ published at Calcutta 
in 1894; while at least seventy additional species have been 
enumerated from the North-western Himalayas. 
Of the family under consideration in the present paper fifty- 
two species are included in the above list by de Nicéville as in- 
habiting the circumscribed district named, while at least five 
others are known to occur in the Himalayas to the west of 
Nepaul, this interesting intervening country at present being a 
terra incognita to the entomologist. The latter remark also 
applies to the continuation of the chain to the east of Sikkim, 
namely, in Bhutan and South-east Thibet, where the Lepidoptera 
fauna will be found, in my opinion, to approximate more closely 
as regards the purely tropical element with the lower woody, 
hilly districts to the south of the Brahmaputra in Assam. When 
these countries are explored entomologically I have no hesitation 
in saying that the number of Papilionids occurring in the entire 
range of the Himalayas will be eventually increased to quite 
seventy. The number enumerated in the preceding catalogue 
as occurring in Sikkim, alone, far exceeds that existing else- 
where in anything like the same area, not only in the remaining 
portion of the excessively rich Indo-Malayan region, to which 
the Himalayas principally belong, but as regards the still richer 
lepidopterological fauna of the neotropical region in South 
America. For although collectively exceedingly rich in Papi- 
lionide, as well as in other families of Rhopalocera, all the 
larger islands of the East Indian Archipelago belonging both 
to the Indo-Malay and Austro-Malay sections, situated either 
directly under the Equator or in close proximity thereto, upon 
