Coiifrihiitions to Experimental Entomology 559 



1883). The species of Junonia differ, therefore, from those of 

 the very closely related, ubiquitous genus Pyrameis Hb., which, 

 according to Standfuss (Handbuch der paiaearkt. Gross-schmet- 

 teilinge, Jena, 1896), also had their origin in the tropics. Gen- 

 erally speaking, however, the species of Junonia are less adaptable 

 than those of Pyrameis. 



The onlv northern representative of the genus Junonia is a 

 member of the coenia group, and I believe that this species had 

 already developed as an independent form before the glacial 

 period, while it was advancing towards the north, and had at least 

 become sufficiently stable to remain as a species after it had been 

 pushed back to the south. When later the road to the north 

 was again open, it was all the easier for this species to follow the 

 path of its ancestors and take possession of the region which the 

 preceding generations had to leave on the approach of the ice age. 



If we now glance at the species of Junonia which are exclusively 

 peculiar to the tropical fauna of America, we are surprised to 

 find that no single species of the group is at all as brilliantly colored 

 as ccenia. All of them have a rather dull coloration and fewer or 

 at any rate smaller eye-spots. The most nearly allied form from 

 which coenia could be supposed to have arisen, is J. genoveva 

 Cramer. Jamaica seems to be the true home of this species, but 

 it has already spread so far over South America that the northern- 

 most limit of its range coincides in part with the southernmost 

 limit of that of J. coenia. Its pattern, which everywhere remains 

 constant, except for the sporadic appearance of slight differences 

 in shade of color, proves that genoveva is phylogenetically a very 

 old form. That genoveva and coenia are to be regarded as two 

 decidedly distinct species and are not to be united in one species, 

 as, for instance, Dyar has done in his "List of North American 

 Butterflies" (Washington, 1902), is proved by the facts, first that 

 there are no true transitions between the two species; second, that 

 from none of the experiments with high temperatures did there 

 result a butterfly which even approximated to the genoveva type. 

 Nevertheless, at least a partial reversion to the primitive form 

 should have taken place through high temperatures if coenia were 

 not a species that had been fixed for a long time, for, since the 



