SEASONAL VARIATIONS OF PAKARGK MICGERA. 218 



rather large size of the two placed between the third median and the 

 second cubital nervures of the hindwings, whilst, on the contrary, the 

 remaining eyespots all tend to become ver)' small and are, in the 

 summer generations, often entirely obliterated. I will shortly point 

 out that nymotypical ti'jdiiis (it should have been spelt with double /) 

 is the summer one, and mention the differences between it and the 

 spring generation, which I propose calling TioEr.i.ixA, rnihi (" types " 

 from Lanusei and Ogliastro, in my collection). 



Grade II : It was F. J. Ball who first pointed out (Aiuialcs Sor. 

 Kntoiii. de Bel(/i(jiie, Iviii., p. 177 (1914), that there exists a difference 

 between the two generations of meffera of Central Europe. He named 

 the second one filipluma, from Belgian specimens, because it differs 

 microscopically from the first by having a thinner distal end to the 

 androconial scales : the only character, visible to the naked eye, he 

 detected is that the broad fulvous space of the forewiug, which contains 

 the apical eye-spot, is not split up into five separate spaces by streaks 

 on the nervures, as it is in the first generation. In the specimens I 

 have at hand I might say this feature I do not see, but, its existence 

 may, of course, depend on localities and years. I find, on the other 

 hand, perfectly constant characteristics on the underside of the hind- 

 wing. To describe them it would be sufficient to say simply that they 

 are one grade away from nymotypical spring ineijera along the main 

 line of variation of the species, as described above, but to be clearer I 

 will briefly mention them again : the diffused scaling is not as uniform, 

 on account of narrow spaces which appear along the streaks and round 

 the eye-spots, splitting it up into bands and patches ; the streaks and 

 the circles round the eye-spots are darker and stand out more ; the pre- 

 marginal lunules, especially, become darker along their outer outline, 

 becoming as dark as the streaks, instead of being of the same tone as 

 the diffused scaling; the circles round the eye-spots are slightly broader 

 on the average ; all this gives the wing a more variegated appearance 

 and givr-3 one the impression of a dark complex pattern standing out 

 on a light ground colour. It must be understood, however, that, though 

 I find these features are always detectable, even in the most northern 

 regions, it needs a little attention to see them in the races of Northern 

 and Central Europe. As one proceeds southwards they become more 

 striking, and one then meets with extreme individuals which recall the 

 more southern races. At the same time one also observes a gradual 

 decrease in the average extent of the dark markings on the upperside 

 in the summer generation, or generations, whereas the spring genera- 

 tion remains as a rule unaltered, except in the Italian zone ; seasonal 

 dimorphism thus becomes more prominent. As might have been 

 expected, the darkest summer generation is the one I have named 

 Caledonia, in the Bull. Soc. Knt. de France, 1911, p. 814, pi. i., fig. 12, 

 from a series collected on the northern coast of Scotland, in August, 

 It is noteworthy that in this race, notwithstanding the high latitude, 

 the summer characteristics of the underside are constantly quite 

 marked. 



The summer generations of race tifielitis differ from the first in 

 exactly the same way as do, from each other, those of the Continent, 

 by the upperside reduced extent of the black markings, which are 

 extremely thin, and even partly obliterated on the outer part of the 



