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 Ehopalocera 

 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 Nic^ville, 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 Nic6ville 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 Papilionidae 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- 

 lionidse, as well as in other families of Ehopalocera, 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 



