DISTRIBUTION OF PAPILIONID^E IN THE HIMALAYAS. 201 



enumerated as being indigenous thereto — that is, undergoing 

 their metamorphoses there: — Byasa latreillii, Achillides krishna, 

 A. arcturuSf Teniopalpus imperialis. 



While in the "interior" I have only met with the penulti- 

 mate species named, with a certainty, though I occasionally saw, 

 but was not able to procure, specimens of a large black species, 

 which I think possibly was the above-mentioned Byasa latreillii 

 (better known as P. minereus). This happened near the junction 

 of that exceedingly interesting district mentioned by Sir Joseph 

 Hooker in his ' Himalayan Journals,' which constitutes the 

 transitional area between the Indo-Malayan and Palaearctic 

 regions, in which one may almost in the space of a few yards 

 pass at once from a tropical to a temperate fauna and flora. 



Between 10,000 ft. and 12,500 ft., which corresponds to the 

 lower alpine zone, the only species which is indigenous therein 

 is Papillo machaon,^ which is, moreover, confined, as far as my 

 experience is concerned, to the lower portion thereof, although 

 several wanderers from the tropical zones occasionally pay it a 

 visit during warm spella of sunshine at the height of the south- 

 west monsoon, but they must invariably soon perish, like the 

 locusts which sometimes succumb in swarms among the snow. 

 I have thus seen males of Iliades agenor as high as 11,000 ft. at 

 Yatung in the Chumbi Valley, in Thibet, which is physically, 

 though not politically, part of the Bhutanese Himalayas. Tropi- 

 cal species of other families occasionally soar even higher still 

 during exceptional spells of warm sunny weather experienced at 

 intervals towards the middle heights, but they none of them 

 perform their metamorphoses at anything like these elevations 

 in the Himalayas, though they look sufficiently out of place in 

 the winged state among the forests of firs and larches which 

 clothe the mountains above 10,000 ft., as in like manner near 

 the sea-level in Norway. 



Towards the upper limits of the sub-alpine belt — that is, on 

 approaching the termination of the forests of conifers — no species 

 of Papilionidae are apparently indigenous, t but on making an 

 exit into the upper alpine or pseudo-arctic zone at 13,000 to 

 14,000 ft. or thereabouts, and arriving in the belt of bushes, 

 gregarious rhododendrons of various species predominating, 

 several species of Parnassius are encountered, which occur from 

 thence right up to the perpetual line of congelation. This latter 

 phenomenon prevails at an average elevation of from 16,000 to 

 18,000 ft. above the sea-level on the southern declivities of the 

 meridional ridge of the Central Himalayas in Sikkim, though it 

 is as much as from 1000 to 2000 ft. higher on the northern 



* This refers to the South-eastern Himalayas only. In the Simla district 

 Dr. G. B. Longstaff has met with Parnassius hardwichei as low as 10,000 ft. 

 within the present belt. 



+ Ibid. 



