1886.] MR. H, J. ELWES ON THE GENUS PARNASSIUS. 15 



interesting problem for the future to discover how the organs of 

 such curious species as P. ncco, P. charltonius, P. imperator, or 

 P. tenedius are produced, and why insects so very similar in appearance 

 as P.jacquemonti and actiiis, or P. charltonius and imperator, have 

 such very differently shaped pouches. 



The distribution of this genus is entirely confined to the Palae- 

 arctic region, and in this respect it is peculiar, among lai-ge and 

 important genera, with Melitcea and Erebia, which have an almost 

 exactly similar distribution, though Erebia is more arctic than either 

 of them. In the Nearctic region, which, as I have before mentioned, 

 can hardly be separated from the Palsearctic region on the ground 

 of any peculiarity among the Lepidoptera, it is confined, as is 

 Erebia, and, with triflmg exceptions, Melitcpa, to the Rocky 

 Mountains and country west of them. It is most numerously 

 represented in the mountain-ranges of Turkestan, Southern Siberia, 

 and the Himalaya, having only three species out of 23 in Europe; 

 none in North Africa ; none within the Arctic Circle, though 

 P. mnemosyne and P. eversmanni come within a few degrees of it. 



Of all the sections into which I have divided the genus, only two, 

 namely the apollo and 7nnemosyne groups, have a wide range, and 

 only these two have developed any marked specific differences ; all 

 the rest of tlie groups, most of which are monotypic, being confined 

 to limited areas in Central Asia. It is almost certain that several 

 species remain to be discovered in the mountainous regions of 

 Mongolia, Tibet, and North-western China ; but many years must 

 elapse before we can liave auy complete knowledge of the natural 

 productions of these extremely distant, inhospitable, and elevated 

 regions. 



Parnassius in one respect is unique among Rhopalocera, namely, 

 that though in a great part of its range a genus most characteristic 

 of mountain-ranges, and most abundantly represented where, as in 

 Ladak and the mountains of Khokand, the climate is of an almost 

 Arctic character, yet it does not occur anywhere in the Arctic 

 Regions. Golias, Argynnis, Erebia, and Chionobas, with which 

 Parnassius is generally associated in Europe, Asia, and America, are 

 all typically Arctic genera. Why, then, is Parnassius, which finds a 

 home at as great an elevation as any other known butterfly, absent ? 



Though in Europe generally looked on as mountain butterflies, 

 several of the species, as P. apollo, mnemosyne, bremeri, eversmanni, 

 and nomion, are also found in low and wooded districts. Eversmanni is 

 said to be an inhabitant of deep bogs. Mnemosyne, though ascending 

 the xAlps to 5000 feet or more in Western Central Europe, in Eastern 

 Europe is found commonly in the steppes. Apollonius also occurs 

 both in saline steppes and high mountains. 



The following Table shows the general distribution of the species, 

 but it must be understood that almost everywhere the species are 

 found in somewhat restricted localities, and not generally through 

 the country. 



