PLEBEIUS ARGUS. 207 



wanting in argus. Oberthur observes (Etudes, etc., v., p. 21) that 

 Plebeius argus (aegon) " varies greatly in different localities, as also 

 -does its congener P. argyrognomon,irom. which it is sometimes difficult to 

 ■distinguish it with certainty. In Brittany, argus (aeyon) is very large, 

 and its size often surpasses that of argyrognomon, but the two species 

 differ greatly in the shade of blue in the J , being always more violet 

 in argyrognomon, and in the tint of the underside of the wings, grey- 

 white in argus, darker (brown) in argyrognomon : further, the latter 

 always emerges one or two weeks earlier than argus, and is passe when 

 -argus is quite fresh. At Zermatt, argus is very small, and the g has 

 the wings margined with a very wide blackish border. In the Pyrenees- 

 Orientales at Vernet, argus $ is large, pale, less widely- bordered with black, 

 and the marginal dots of thehindwing are very pronounced" ( = hypochio- 

 noides,antea p. 199). "At Cannes, the type appears to be smaller, and if one 

 may judge by captures made in June 1876, the J tends to be of a very 

 pale blue, with a slightly greenish tinge. At Madrid, the type of argus 

 differs little from that of Vernet. In Dauphiny, near Uriage, a very 

 large form of argyrognomon is found, of which the 2 is sprinkled with 

 blue scales on the underside, and a form of argus very similar to that 

 of Brittany, flying at nearly 900 metres altitude ; further, one finds in 

 a southern locality, on the road from Grenoble, a species of which the 

 $ is as widely blue above as ceronus ; this species, which Boisduval 

 called acreon, Fab., in his collection, and treated as a variety of 

 -argyroynomon in the Index Methodicus, 1840, p. 11*, is very distinct in 

 the flax-grey tint of its wings beneath, and the reduction, and even 

 obliteration, of the black spots, particularly those of the median 

 part of the wings. In Andalusia, near Granada (Alfakar), and above 

 Lanjaron, towards the Picacho de Veleta, Mr. R. Oberthur captured, 

 in 1879, in abundance, hypochiona, Ramb., which is to be regarded as 

 •a variety of aryus, although Staudinger, in his Cataloy, 1871, p. 10, 

 treats it as a variety of argyrognomon ; this butterfly differs from the 

 French form of argus, by the brilliant sheen of the blue of the upper- 

 side, and the remarkably bright white of the underside, of the wings in 

 the $ ; the $ , generally brown above, but sometimes strewn with 

 blue scales, is below of a clear yellowish-tawny, very bright, and the 

 marginal golden -blue points are very accentuated. In the same 

 locality, argyrognomon is to be found, differing from J argus, by the 

 underside of the wings being of a grey-brown, and approaching greatly 

 to the French form. This colour of the underside of the wings in the 

 $ , appears to me significant, although certain examples of both 

 species are sometimes sufficiently intermediate to be embarrassing, 

 but, in the immense majority of cases, it is a very certain guide, and 

 it is largely on this account that I refer to argus (aegon) the Lycasnid 

 from Askold ; above, it differs little from argyroynomon, the colour of 

 the J is of a darker blue, the margin of the wings is very narrowly 

 black, but beneath, the tint of the J is of a whitish-grey, that of the 

 2 from Askold is not even so brown as that of the $ argyrognomon 

 of France. However, the underside of the $ argus is known to come 

 somewhat near the tint of $ argyrognomon. David has taken, in the 

 north of China, a form of argus similar to that from Askold, but 

 smaller." Later, in Etudes, viii., p. 15, Oberthur adds : " The two 



* Referred to infra p. 208, as calliopis, Bdv. (Icones, p. 58). 



