SIZE-VARIATION OF MELITiEA ATHALIA. 59 



to low temperatures he was able, in V. io nh. jischeri, Stdfss., to 

 produce strong facial transition to V. urticce, which, at least in 

 the fore wings, was very great, especially if the local (" climatic " 

 and seasonal) form of V. urtica var. iclimisa is taken for com- 

 parison. Normal British V. io, induced by the cool, contrastless 

 climate, are more or less transitory in fades to this urticce-form 

 aberration, ab.fischeri, Stdfss. On the other hand, V.urticce pre- 

 serves its facial ioform tendency, and exhibits it also in seasonal 

 vai'iation, extreme aberrations, for instance, ab. ioprotoformis , ab. 

 ioformis, and in existing local (climatic) varieties. In this sense 

 V. io appears as a palse-entomological variety of V. urticce, which 

 became a "species " by losing its sexual affinity to the type. 



SIZE-VARIATION OF MELIT.EA ATHALIA. 



By Rev. Frank E. Lowe, M.A., F.E.S. 



While preparing notes of some of my captures last summer, 

 the January issue of the ' Entomologist ' came to hand, in 

 which Mr. Wheeler refers to specimens of Melitcea athalia taken 

 by me at Reazzino {antea, p. 10). There can be no doubt that 

 he is right in saying that at present " with very few exceptions it 

 seems hopeless to give characteristics for local races of this species, 

 for three reasons," which he enumerates. Against the asserted 

 tendency to a decrease in size south of the Alpes, teste Riihl and 

 others, he adduces many exceptions from his own experience. To 

 me it appears that this decrease in size may be true when you get 

 ivell away from the Alps, perhaps in the plains of which I know 

 nothing, but not in the mountainous districts themselves. For 

 instance, at Orta and in the Val Strona, Iselle and its neighbour- 

 hood, athalia is often above the average in size and brilliancy of 

 colour as compared with specimens from the Rhone Valley or 

 Caux. In South France again, to my surprise, all specimenswhich 

 I have taken at Digne or Gavarnie were small of a poor form. 

 But, as Mr. Wheeler says, " in many localities such different 

 forms are found together" that it is difficult often to find any- 

 thing characteristic of a locality, especially in the matter of size. 

 This may be exemplified from my Reazzino specimens, all of 

 which I did not send to Mr. Wheeler. Some of these are 

 decidedly small (he is right in supposing that they were taken 

 on the same ground as the " britomartis"), one female measures 

 only 31 mm., while, as instances in the other direction, some 

 measure 43 mm., and males 40 mm. Again, some of my largest 

 specimens are from Orta, males often reaching an expanse of 41. 

 From the Tyrol, i.e., the Mendel, Brenner, and Trafoi, speci- 

 mens appear to be uniformly smaller than those from the Swiss 

 mountains. 



