THE ATHALIA GROUP OF THE GENUS MELIT^A. 9 



specimens), and asteria, and the same tendency shows itself 

 occasionally even in dictynna and hritomartis. I do not, how- 

 ever, remember to have seen it either in aurelia or varia, and 

 certainly have not done so in the case either of berlsalensis or of 

 diciynnoides. An opposite form of aberration in which this 

 inner baud is enlarged at the expense of the basal band and the 

 light spot, and sometimes of the central band also, is occa- 

 sionally to be seen in all the species, but is more nsual in 

 aurelia, varia, and the others in which the lighter aberration is 

 least common. A great difference in facies is produced by the 

 great difference which exists in the breadth of the central band, 

 and in the comparative breadth of the two parts into which it is 

 normally divided, though the latter observation does not, of 

 course, refer to deione and asteria, in which the two divisions 

 are of the same shade. A not uncommon form of aberration, 

 especially in athalia, is the absence of the division in this band ; 

 in cases where the band itself is also unusually broad the effect 

 is almost startling ; there is a magnificent example of this in the 

 National Collection. The other bands of the un. s. h. w. are 

 also liable to great differences in breadth and intensity of colour, 

 especially perhaps in the size of the lunular portion of the 

 terminal band. I have already mentioned the tendency of the 

 light spot to coalesce with the third spot of the basal band. I 

 have seen this occur in every species, and possess examples of it 

 in all except asteria. The principal, if not the only, forms of 

 aberration on the f. w. un. s. consist in the intensification or 

 obsolescence of the black markings, and of the number of, and 

 the greater or less prominence given to, the light submarginal 

 lunules. 



On the upper side the greater or less breadth of the black 

 markings, their obsolescence or exaggeration into melanism, 

 their sharpness or suffusion, and to a less extent their angula- 

 tion, form one great cause of aberration, the other is the intensity 

 and the variegation of the ground colour. All these forms of 

 aberration are, to some extent at least, common to all the species, 

 but I think it may be safely asserted that variegation in the 

 ground colour is confined in this group to the female. A very 

 wide and difficult question is opened up by the approaches made, 

 individually or racially, by one species towards another, but this 

 will perhaps be best dealt with in considering the range of 

 variation in each species. 



As athalia is at present the dominant species in Europe, and 

 is also that to which all the other species except those of the 

 high mountains, viz. asteria and varia, are usually considered to 

 approach most nearly, it will be well to take it first. With very 

 few exceptions it seems hopeless to give characteristics for local 

 races of this species for three reasons : first, because in many 

 localities such different forms are found together ; secondly, 



