LYCAENA ARION. 305 



(b) The hindwings are occasionally quite unspotted; sometimes they bave a 



band of black dots or sometimes of black spots ; sometimes, instead of 

 the band, only isolated spots or dots are present. 



(c) The margin of the hindwings is sometimes very broad, without darker 



spots, sometimes very narrow, and then black spots appear with a pale 

 cloudy ring round them. 



(d) The ground colour is sometimes a paler and sometimes a more intense. 



blue. Sometimes it is so dark that it comes near to black. 



(e) In size tbis butterfly also varies. One linds specimens which hardly reach 



the size of argus (Borkhausen). 



With regard to the underside, however, where the variation is 

 really as marked as on the upper surface, he observes that it is alike in 

 all cases, relying on this to show the specific identity of the various 

 forms he cites. 



Priihstorfer has divided avion into a number of " sub-species," 

 founded generally on a few insects taken from time to time in different 

 localities, which he dignifies with the name of local races. Practically 

 all other entomologists agree in the ob-ervation that both in size and 

 markings this species is remarkably variable throughout most of its 

 range, and that it is very rarely that any form of variation is at all 

 confined to any special locality, though certain peculiarities are often 

 predominant. For instance the mountain specimens are generally 

 more or less suffused with black, but Wheeler observes (Ent. Becovd, 

 xiii., p. 119) that at Miirren, which is at the same altitude as Zermatt, 

 " avion resembles the form of the lowlands, being very bright and 

 clearly marked, with no inclination towards var. obscura" On the 

 other hand the darkest form described, ab. aldvovandns } de Sel.-Lngch., 

 which has the whole upper surface suffused with black, with only a 

 slight dusting of blue basally, was named from a specimen taken at 

 the foot of Mt. Vesuvius, while Wheeler (in litt.) notes another in his 

 collection exactly corresponding with this, taken at Iselle, near the 

 bottom of the southern slope of the Simplon. No one who has 

 collected butterflies in the Alps can fail to be aware how frequently 

 ab. obscura, Christ, is to be found among large, broad-bordered, but 

 basally bright blue, specimens, to which this name should not, strictly 

 speaking, be applied ; and it is impossible to deprecate too strongly the 

 misuse of terms by which alone such a form can be called a sub-species; 

 and still less can the term be legitimately employed to designate 

 forms of which half-a-dozen or less have been taken in the same 

 neighbourhood. We have frequently objected altogether to the use of 

 the term, but, if it be employed at all, it should at least be confined to 

 forms which so greatly predominate in a given locality, that others, 

 which may occur among them, can only be regarded as casual 

 aberrations, obviously in process of being weeded out. 



Oberthiir, (Lip. Uomp., iv., p. 326) has demonstrated precisely the 

 condition of local races in this species. He says: — "Examination of 

 avion from these different localities* shows that there is in each a race 

 whose facies or general appearance is distinctive, but with an admixture 

 of examples lecalling those which constitute the majority in other 

 localities. Thus, w T herever avion flies there are large and small speci- 



* He has ennumerated England, Brittany, the Pyrenees-orientales, the 

 Italian Riviera, the Alpes-maritimes, Digne, Zermatt, the Tyrol, Fusio, Stresa, 

 Greece, the Bernese Oberland, the Bernese Jura, Savoie, Corsica, Lozere, Gironde, 

 Charente, the Hautes-Alpes, Doubs, Lake Baikal and East Turkestan. 



