THE ENTOMOLOGIST 



Vol. XLI.] JUNE, 1908. [No. 541 



THE ATHALIA GEOUP OF THE GENUS MELIT^A. 



By George Wheeler, M.A., F.E.S. 



With the possible exception of the black-and-white ' ' skippers, ' ' 

 there is probably no group of European butterflies which causes 

 more difficulty than those species of the genus Melitcea which 

 are usually grouped round athalia. No doubt it is, as a rule, 

 easy enough for any one with a slight acquaintance with the 

 various species to separate them, when the individuals are few 

 in number and the localities restricted ; but when long series 

 from many and widely separated localities are examined (and 

 frequently with only fragmentary data, or none at all, attached 

 to them), the difficulty of separating the species and of naming 

 all specimens correctly becomes almost insuperable. For this 

 difficulty two principal causes are responsible : first, the close 

 resemblance inter se of the different species, and, secondly, the 

 very great range of variation in each species, though always 

 within certain definite limits. But it is the combination of 

 these two difficulties which makes this group of almost un- 

 equalled biological interest amongst European butterflies ; for 

 we have here exactly the condition of things which was long ago 

 laid down by Darwin (' Origin of Species,' chap ii.) as that^ 

 which it is easiest to see species as it were in the making. If 

 species have been evolved from previously existing ones, it would 

 be a most remarkable circumstance if we could find no examples 

 of the process taking place under our eyes ; yet the majority of 

 collectors (if not even of naturalists) who give an unhesitating 

 assent to some theory of evolution, seem to expect to find it 

 possible in all cases to say with certainty to what species any 

 given insect belongs ; disregarding in practice the possibility, 

 nay, the extreme probability, that amongst the number of the 

 European butterflies, many of which are very variable, some few 

 may be expected to exhibit the process of species-making, or, in 

 other words, to afford instances of species not yet absolutely 

 differentiated from each other, and to certain individuals of which 

 it is therefore impossible to assign with certainty the correct 



ENTOM. — JUNE, 1908. M 



