﻿48 LÉPIDOPTÉROLOGIE COMPARÉE 



with the ground colour of the rest of the wing, in Aegus it is 

 more or less defînitely white. This seems a very small and trivial 

 point but it is very constant and is the différence between the 

 two species that may be really depended upon. 



The orange marks take a definite part in the structure of thèse 

 spots that differ so much in Aegus from Argus. In the latter it 

 is either a séries of separate spots or if, as is more usual, they 

 are united to form a band, this band is very zig-zag, the points 

 of the arrowheads reaching down towards the sides of the 

 central spots of the ocelli. In Aegus it is a more continuons 

 band, the flat arches of the inner row of black spots leaving its 

 inner edge moderately straight. This is very évident in com- 

 paring Aegus with such a well-marked form as Armoricanus, in 

 which at first glance one is inclined to say the orange is much 

 more a strong band than in Aegus, but though the colour is more 

 intense and there may be as great or even a greater area of it, 

 it has not so continuons an appearance as in Aegus and whilst 

 a broad line could be drawn right along the band in Aegus, in 

 Armoricanus the most slender line would hâve to wave up and 

 down to avoid the black spots on either side of the orange band. 



Thèse différences are well brought out in the photographs by 

 Mr. Tonge, showing the undersides of spécimens of Armorï- 

 canus, of a fairly typical Argus from Le Lautaret and of Aegî/s. 



I do not propose to describe the American and Asiatic forms 

 related to Aeg/is but they agrée generally in thèse différences 

 and especially in the white submarginal line or band. 



Thèse distinctions are based on maie spécimens, in the females 

 the characters are less strongly defined. Females of Aegus may 

 show a definite amount of arrowhead form of the black spots 

 on the hind-wings, rarely on the fore-wings, and in occasional 

 spécimens the marginal area (or line) that is white in Aegus, is 

 pale in Argus especially again on the hind-wing, so that one 

 can almost call it white, though not quite of the clear white of 

 Aegus. In both species and both sexes, the spécifie différences 

 are less pronounced on the hind-wings than on the fore-wings, 



