DISTRIBUTION OF PAPILIONIDA IN THE HIMALAYAS. 201 
enumerated as being indigenous thereto—that is, undergoing 
their metamorphoses there:—Byasa latreillii, Achillides krishna, 
A. arcturus, Teniopalpus imperialis. 
While in the “interior” I have only met with the penulti- 
mate species named, with a certainty, though I occasionally saw, 
but wag not able to procure, specimens of a large black species, 
which I think possibly was the above-mentioned Byasa latreallit 
(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 Palearctic 
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 Papilio 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 spells 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 ag 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 Papilionide are apparently indigenous,t but on making an 
exit into the upper alpine or pseudo-arctic zone at 138,000 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 hardwickei as low as 10,000 ft. 
within the present belt. 
+ Ibid. 
