172 BRITISH BUTTERFLIES. 



deal, has presented a greater number of races, almost all due apparently 

 to local conditions of altitude, latitude, and perhaps some geological 

 and geographical factors of environment. The impress of these 

 conditions is such as to lead us to recognise almost at sight the origin 

 of individuals coming from lowland, highland, heath, and moorland 

 districts, at least in the $ s, and not infrequently in the £ s. These 

 races are not only, as here indicated, in their broad features fairly 

 recognisable, but each of them presents, within its own racial limits, 

 most interesting aberrational features in the tint of the ground colour, 

 width of the dark marginal band, development of the discoidal lunules, 

 etc., in the upperside of the $ s, and in the ground colour, as well as 

 the quantity and intensity of the orange markings on all the wings, of 

 the 2 '■> on the underside the variation is, perhaps, still more marked, 

 the ground colour varying racially from white, through bluish- and 

 greyish-white to greyish-brown in the $ s, and pale grey-brown or 

 grey-ochreous to a somewhat deep brown in the $ s. The underside 

 spots also vary considerably in size, and somewhat in direction, the 

 orange submarginal band both in intensity and extent, and the 

 beautiful marginal " silver studs," also in number, size, and tint. 

 The variation in size is extreme ; the two largest races, bejarensis and 

 coreana (inhabiting almost the extreme western and eastern limits of 

 the species), reach 35mm. -36mm., and are difficult to distinguish apart, 

 though quite unlike any other races, whilst the smallest examples of 

 our European mountain form philonomus, do not exceed 18mm. Of. 

 the general size variation, Chapman notes specimens from Tragacete 

 30mm., Carinthia 29mm., Locarno 25mm., etc. Blachier gives the 

 average size of specimens from the Geneva district as 24mm. for both 

 sexes, whilst Reverdin gives his largest $ as 26mm. (from the Taren- 

 taise), the largest ? 23mm. (from Schallberg), the smallest $ 20mm. 

 (from Alpienalp), the smallest $ 19mm. (from Berisal); Behfous notes 

 that, in the Cote d'Or, the size varies from 19mm. -27mm. the average 

 about 22mm. ; Rebel states that the specimens from Sofia and Slivno 

 are small, the $ s varying from 20mm. -23mm., the ? s from 22mm.- 

 25mm. Wheeler observes that, in Switzerland, the variation in size is 

 very noticeable, increasing up to 32mm. in the hotter localities — Sierra 

 and the Rhone banks at Bouveret producing largo examples, and the 

 mountain districts smaller ones, sometimes even less than 23mm. 

 Staudinger reports the $ s from the Ala Tau as very large, with broad 

 black band, whilst Romanoff states that the specimens from Kasikopa inn 

 are remarkably small. Apart, however, from racial size, the examples 

 of the various plain and mountain forms vary much inter s«, even in 

 the same locality, and it might be well to look on examples above 

 27mm. in expanse, as ab. major, and less than 28mm., as ab. minor. 

 Grand is the only observer who notes a seasonal dimorphism in size. He 

 says that in Croatia (at Agram), the species is very common in the whole 

 district, a first generation in May and June, with a wing-expanse of 

 from 24mm. -29mm., the second, from July to September, from 20mm.- 

 26mm. ; in the second half of August, and sometimes in September, 

 very small specimens 20mm. -21mm., are common, perhaps belonging 

 to a partial third generation. Our British specimens fall into three 

 very distinct races. (1) The chalkhill race, the $ s with very narrow 

 dark marginal border to forewings. and spots on hindwings, of fairly 

 large size, and pale underside ; the ? S sometimes shaded with bhie= 



