THE CHALK HILL BLUE. 167 



The Chalk Hill Blue (Lycccna corydon). 



Although this butterfly (Plate 109) is, in England, fairly 

 constant in the matter of colour, and, as regards the male 

 especially, differences in tint are noticeable when series from 

 various localities are ranged side by side. Silvery-blue 

 perhaps best expresses the general colour of the male on the 

 upper surface, sometimes very pale, and sometimes faintly 

 tinged with greenish. The blackish border on the outer margin 

 of the fore wings varies in width and in intensity ; often there 

 are indications of eyed spots on this margin, and occasionally 

 these spots are quite distinct, although the whitish rings are not 

 always clearly outlined. The black border on the outer margin 

 of the hind wings is often narrow and external to a series of 

 white-edged black spots, but sometimes it is broad and 

 obscures the spots ; orange markings rarely appear on this 

 margin, but such aberrations have been taken on the Dorset 

 coast. The fringes are white chequered with blackish on the 

 fore wings, but with seeming continuation of the veins through 

 those of the hind wings. The female is sooty-brown above, 

 with a black discal spot on the fore wings, and sometimes on 

 the hind wings also, and these spots may be ringed with blue 

 or bluish-white ; the outer marginal borders are hardly darker, 

 and those on the fore wings are limited by a wavy pale line, 

 which may be faintly or strongly marked with orange, but 

 orange marking on these wings is rather the exception than 

 the rule ; on the outer margin of the hind wings there are 

 some black spots, edged outwardly with white and inwardly with 

 orange. The fringes are white chequered with brown, and those 

 of the fore wings are tinged with brown. There are generally 

 some blue scales at the base of the fore wings and over a larger 

 portion of the basal area of the hind wings, but occasionally the 

 whole discal area of the hind wings (Fig. 7, Plate 117), or of all 



