202 THE ENTOMOLOGIST. 
or Thibetan side, an anomaly which has been sufficiently explained 
by Sir J. W. Hooker in his well-known ‘ Himalayan Journals.’ 
The snow zone is practically only a continuation of the 
preceding, characterized botanically by its dwarf alpine herbs, 
the same as in the polar regions; while among the Parnassine, 
so typical of the lepidopterological fauna of the more elevated 
mountains of northern Asia and Europe, three species occur in 
Sikkim—Parnassius hardwicket, jacguemonti, and acco; with 
three others in the continuation of the chain towards the north- 
west—Parnassius charltonius, actius, and stoliczkanus. Of these 
I collected P. hardwicket and P. jacquemonti, both as high as 
18,000 ft. on the southern ascent of the Donkia Pass, in close 
proximity to the Thibetan frontier. 
In drawing up the accompanying list illustrating the vertical 
distribution of the Himalayan Papilionide, I have been guided 
principally by my own personal experiences in the Sikkim 
Himalayas, but where such first-hand information was wanting 
I have supplemented it by making use of the data contained in 
the ‘ List of the Butterflies of Sikkim,’ by Lionel de Nicéville, 
already alluded to, as well as the admirable ‘‘ Catalogue of the 
Lepidoptera of Sikkim,” by Mr. H. J. Elwes, with the assistance 
of the late Otter Moller, published in the ‘ Transactions of the 
Entomological Society of London in 1888.’ My principal object 
in compiling the same is to elicit further information respecting 
the vertical range of species which are either very rare or un- 
represented in that part of the Himalayan chain which I visited, 
and must be considered as only of a preliminary character. 
The chief difficulty in the way of tabulating the vertical distri- 
bution of the Himalayan Lepidoptera consists in not being able 
to distinguish between those species which are truly indigenous 
to the various climatal zones—that is, performing their meta- 
morphoses there, as most of the commoner species occasionally 
occur in the winged state only for several thousand feet above 
the altitude at which they underwent their transformations, 
either through a spirit of adventure, or by being carried up 
involuntarily, in a measure, by warm ascending currents of air, 
as I have frequently seen them during exceptional spells of hot 
weather experienced during the progress of the south-west 
monsoon. What is absolutely necessary is to ascertain where 
the different species undergo their adolescent existence, and this 
was out of the question during a short stay of seven months in 
the districts under consideration. 
In the accompanying table the numbers in the columns 
correspond to the following climatal zones as defined by that 
great scientific traveller Baron Humboldt :— 
(1. Equatorial Zone ge .... Unrepresented.) 
2. Tropical Zone... Pe ... 200-2500 ft. 
3. Sub-Tropical Zone ees ... 2500-5000 ft. 
4. Warm Temperate Zone ... 5000-7500 ft. 
