562 William Reiff 



the white and red scale formations are replaced more or less by 

 black, eye-spots all smaller and tending to disappear, and the 

 disappearance of the halo surrounding the eye-spot so that the 

 center begins to shade over into the ground color. It is to be 

 noted also that the two red spots on the anterior border of the 

 anterior wing are scarcely changed in the slightest degree, either 

 in these or in the experiments with warmth, and this must point 

 to a great phylogenetic age for this portion of the markings which 

 is so characteristic of the species of Junonia. If, however, as I 

 have said, there is no atavism in these cold forms, we must regard 

 the changed specimens as being without doubt progressive forms. 

 It seems peculiar, and certainly it may be advanced as an objection, 

 that one species of butterfly can have two prospective forms, which 

 nevertheless, are in strongest contrast to each other. Let us 

 examine this question more closely. 



As I have stated before, J. coenia will probably take on, in the 

 not very distant future, a somewhat diff'erent coloration and pat- 

 tern in the portions of North America which it has continuously 

 inhabited. In these regions and because of the mild winters, 

 there has been no obstacle to the survival of the species, but the 

 conditions have been quite diff'erent in the northernmost portions 

 of its range, for here J. coenia can never become indigenous on 

 account of the severe cold of winter unless the species acquires 

 the habit of hibernating. As I have said in the beginning of this 

 paper, caterpillars and pupae of coenia die at what would be a 

 very slight fall of temperature for the northern winter. Hiber- 

 nation of the eggs can hardly come into the question, for the last 

 generation of our Pyrameis species, which, as I have several times 

 remarked, are closely related to Junonia, does not pair till spring. 

 Moreover, it is also known that butterflies pair, as a rule, only 

 after having flow^n for a considerable period. For the generation 

 of coenia which hatches in its northern range from the end of 

 October on, there would not be sufficient tmie to attain sexual 

 maturity, but this msect does not, as a rule, hibernate in the north 

 even as an imago. No doubt the last generation attempts this, 

 but only a few specimens survive the winter. How could we other- 

 wise understand that in spring the butterfly is a great rarity in 



