558 * William Reiff 



which runs parallel with the outer margin, is almost completely 

 supplanted by the dark ground color of the posterior wings, and 

 is no longer to be detected in the anterior wings. The small white 

 apical spot is very variable. Although it has all disappeared in 

 rather light-colored specimens, it continues to remain more dis- 

 tinctly visible in dark specimens. All the eye-spots are diminished 

 in size through the effects of cold. Instead of there being new 

 adventitious markings, the markings already existing have begun 

 to disappear. The most posterior eye-spot of the hind wings 

 often consists only of a tiny dot, while the remaining eye-spots 

 towards the outer margin lose their rings, and the ground color, 

 therefore, goes over into the inner marking. The two red spots 

 towards the anterior border of the fore-wing are least influenced 

 by these changes. The inferior surface of the anterior wings 

 corresponds to that of the upper surface. That of the hind wings 

 is uniform silver gray, with a pale brownish tint and a scarcely 

 perceptible pattern. 



WHAT CONCLUSIONS MAY BE DRAWN FROM THESE EXPERIMENTS ? 



We may assume as established beyond question that the genus 

 Junonia had its origin in the tropical zone, where even today most 

 of the species of the genus are to be found, and whence the species 

 migrated and spread in the direction of the two poles till a limit 

 was set to their expansion by the coming of the glacial period. 

 The more the northern regions were covered with ice, the more 

 Junonia had to retreat to the south. The conditions in the 

 subtropical zone, in which the genus was able to spread in all 

 directions without meeting with any obstacle, were difi^erent. 

 After the glacial period, and hence not so very long ago, a gradual 

 northward migration again began. 



There are species of Junonia in the tropics both of the old 

 world and the new world, but they are to be found in the north 

 temperate zone only in North America, where the north is not 

 separate from the south by mountain ranges, although it has been 

 shown that North America passed through a longer glacial period 

 than Europe (J. Hann, Handbuch der Klimatologie, Stuttgart, 



