192 BRITISH BVTTEEFLIES 



with a border of reddish spots, and a niiuiber of black spots in white 

 rings, the arrangement of which is here represented. 



The butterfly frequents challiy downs, chiefly in the south of 

 England, and seems to be im.known in Scotland and Ireland. The 

 Isle of Wight, and the chalky downs and banks of Sussex, Surrey, 

 and Kent, are its favourite localities ; and even in these it is generally 

 very local, sometimes swarming on a grassy bank of no great extent, 

 when the surrounding neighbourhood, though apparently equally 

 suitable to its requirements, does not harbour a single specimen. 

 It is on the wing in May and June, and again in August. 



The caterpillar is green, with two rows of yellow streaks on the 

 back, and a yellow stripe on each side. It feeds on the Dutch clover 

 {Trifoliam repeiiis), horse-shoe vetch {Hippocrcpiti coiitosa), and 

 various other leguminoiis plants. 



The Chalk-Hill Blue [LijCLcna Corijdon) 



The male of this species (Plate VII, fig. 1) is readily to be dis- 

 tinguished from all other members of the genus by its pale glossy 

 blue, but the female (fig. 2 of Plate VII) so closely resembles that 

 of Bellargus that it is often a somewhat difficult matter to dis- 

 criminate between them. The following, however, are a few points 



worthy of observation : The ujjper 



side of the female Corydon has the 



bases of tlie wings more or less 



sprinkled with the pale sillcy blue that 



characterises the male ; and the black 



■ \' ^ '" ^ bars of the fringe are usmtdhj broader 



-^•<* •, ; /■ ' - ' •',''- in C'or//(7on than in Bellarniis. The 



i'i^l^ ;4^>' black-centred spots of the under side 



Yio. 91. The Chalk Hill ^i'6 '^Iso usually more conspicuous in 



Blue — Under Side. the former species than in the latter. 



The difticulty of identification is 

 increased by the fact that both these butterflies frequent similar 

 localities, and are often on the wing at the same time ; but al- 

 though Corijdon is certainly a frequenter of chalky districts, yet it 

 is often found plentifully in districts far removed from the chalk, 

 notably at Arnside in Lancashire, and in Epping Forest. 



The butterfly' is out in June and July. The caterpillar is green, 

 with two rows of short yellow streaks on the back, and a yellow 

 stripe on each side. It feeds on the purple and Dutch cloAcrs 



