NOTES ON THE DISTRIBUTION OF AGRIADES CORIDON. 263 



brown to pale cream) of the ground colour underside hindwing. The 

 2 , on the other hand, is peculiar in that it is found to be much 

 more variable on Royston Heath than in any of the other localities. 

 Thus, considering first the minor variation of the markings on the 

 underside, one notices that it is usually possible to find at Royston a 

 pronounced example of ab. an-uata, whereas I have not yet taken this 

 elsewhe'^e ; at Royston also I have found a very complete ab. obsoleta 

 and several intermediate forms, but very rarely have I noticed any 

 approach to this elsewhere. In all the localities a form occurs with 

 the discoidal spots, fore- and hindwing, ringed with white, but this, too, 

 is perhaps commonest at Royston. With regard to the conspicuous- 

 ness of the orange markings along the borders of fore- and hindwing, 

 there is not much to be said ; every degree of variation in this respect 

 is found in all the localities. 



There is a more striking variation to be found in the ground colour 

 of the underside forewing. In a typical specimen of L. coridon 2 this 

 is of a fairly dark brown, and the black spots are ringed with white. 

 In many specimens in this district the white has spread, until, in a 

 number of instances, the wing has become, with the exception of the 

 border and the spots, entirely white, as in the 3- . Occasionally the 

 colour of the hindwing has become lighter at the same time, and it 

 would not be easy to distinguish at sight such a specimen from a g- 

 by the underside alone. This form occurs in all the localities, but is 

 decidedly more frequent at Roj^ston than elsewhere. 



The most interesting variation of all, which it is the chief object of 

 these notes to record, is found on the upperside, the normal brown of 

 which is more or less replaced on the lower, or on all four wings, by 

 the blue of the J . None of these specimens are quite as completely blue 

 as in the extreme form known as ab. i<y)i(iraplia, but many approximate 

 to it. The majority of the aberrant forms have the lower wing all 

 blue, except the upper fifth, and a variable amount of blue on the fore- 

 wing, and are apparently included in ab. wiiiibrunnea, Mill. It is also pos- 

 sible to find every intermediate stage between ab. sennbnmnea and the 

 typical 5 . Now it is very noticeable that these blue forms are found 

 only on Royston Heath, where they have occurred regularly for the last 

 four years, and are comparatively common. A rough attempt at estimating 

 the proportions gave the result that one specimen in about every fifty or 

 sixty has at least a well-marked blue hindwing. The ab. seiuibrunnea 

 is very conspicuous and may easily be distinguished when fiying from 

 an ordinary $ . I have searched carefully for ab. sewibriinnea in the 

 other localities during three seasons, but without success. I have one 

 specnnen from Fleam Dyke Avith the left forewing splashed irregularly 

 with blue, and a few from the Devil's Dyke showing indications of blue 

 on the hindwings; but that is all. 



It is impossible to ofler any explanation as to the reasons why this 

 local race of blue $ s should have established itself only on Royston 

 Heath, since the conditions are apparently very similar in all the 

 localities. 



There appears to be no relation between this upperside approxima- 

 tion to the J form and the underside approximation mentioned above. 

 Many of the ab. seinibnninea have the white underside forewing, but an 

 equal number have quite typical undersides. 



The ab. sijiu/rapha seems to be found sometimes at Devizes [Knto- 



