236 BRITISH BUTTERFLIES. 



increase, however, in number and in frequency of occurrence towards 

 the north, the black spot being eventually replaced by a white one, 

 sometimes on all four wings. But although this is the general line 

 of variation, there are many exceptions. Wailes observes that " there 

 is no doubt that this band of orange spots is generally most fully 

 developed in the southern localities ; but the supposition that it always 

 decreases as we proceed north is certainly erroneous ; for some of the 

 finest and most brilliant specimens in this particular that I have seen 

 are from parts as far north as Liverpool, from our own district 

 [Durham] , and from Edinburgh ; those from the two latter localities 

 bearing the white spot of artaxerxes." This white spot, again, is not 

 confined entirely to the north, still less to specimens which are of the 

 artaxerxes form beneath. It has been observed, among other localities, 

 as far south as Dartmoor (Leach) and Brighton (Cooke), and from 

 Richmond (Yorks) northward it is by no means uncommon, even 

 where the artaxerxes underside is extremely scarce, if present at all. 

 The variation in the Durham forms of this species, which may be 

 regarded as aberrations of the var. salmacis, is very wide, wider, indeed, 

 than in any other portion of its habitat, and has been closely worked 

 out and described by Harrison (Ent. Record, xvii., pp. 267, 280 ; xviii., 

 p. 236) ; an account of these different forms will be found under vars. 

 salmacis and artaxerxes and their aberrations. The amount of white 

 varies from a few scales to a complete circle when the discoidal spot is 

 black, and in the case of a white discoidal the size ranges from a 

 small dot to 2-5mm. in a specimen taken by Harrison. 



Hodgson, who made a special study of the variation of the 

 Lycaenids in Great Britain, has contributed (in litt.) a number of 

 additional observations on this species. He states that he has found 

 no difference between the specimens taken on chalk and those on sandy 

 soils after long and careful comparison. The variation of the fringes 

 he describes thus : — u Never pure white ; often with dividing line 

 parallel to margin ; often, especially on the forewing, dusky, 

 sometimes nearly, or wholly, brownish, otherwise with stride running- 

 out from the nervures through the fringe." With regard to the white 

 edging exterior to the marginal black spots, he observes that it occurs 

 not uncommonly and in both sexes, though more rarely in the $ , 

 occasionally, though very rarely, on all the wings, but usually only on 

 the hindwing and at the anal angle of the forewing; he adds that there 

 is no tendency to encroach inwards. He also notes the occasional, but 

 very rare, absence of the discoidal spot on the upperside of the fore- 

 wing, and the fact that the»nervures, or the border, or both, may be 

 darker than the rest of the wing, the dark nervures being commoner 

 in the north, the dark border in the south. The greater brilliancy of 

 the orange markings he holds to be coincident with hotter seasons, 

 independent of broods. On the underside he observes that the white 

 marginal band is occasionally increased in breadth at the expense of 

 the orange, and that the black spots contained in it are often small, 

 or nearly, or quite, absent, but more commonly in the north than in 

 the south. He also remarks on the occasional presence, in the south, 

 of white, or whitish, wedge-shaped marks at the points where the 

 basal spots of the forewing occur in other species, and adds that he 

 has one specimen captured in Sussex, in 1889, in which one minute 



