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 Parnassina3, 

 so typical of the lepidopterological fauna of the more elevated 

 mountains of northern Asia and Europe, three species occur in 

 Sikkim — Parnassius hardwickei, jacquemonti, 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. hardivickei 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 Himalaj^an Papilionidse, I have been guided 

 principally by my own personal experiences in the Sikkim 

 Himalayas, but M'here 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 Nic^ville, 

 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 ... ... Unrepresented.) 



2. Tropical Zone 200-2500 ft. 



3. Sub-Tropical Zone 2500-5000 ft. 



4. Warm Temperate Zone ... 5000-7500 ft. 



