234 THE CANADIAN ENTOMOLOGIST. 



chrysalids at the end of June, after fourteen days, forty-five marcellus 

 emerged, but five remained over till the next spring and then emerged 

 telamonides. The explanation of this fact follows very simply from the 

 above stated theory. According to this the two winter forms must be 

 considered as the primary, but the marcellus form as the secondary. But 

 the last is not yet so firmly established as with prorsa, where a reverting 

 of the summer generation to the levana form is only accomplished through 

 special outside influences; while here there are in every generation single 

 individuals with which the inclination towards reversion is still so strong 

 that the extremest heat of summer is incapable of diverting them from 

 their original hereditary disposition, to accelerate their emerging and to 

 force them to take the marcellus form. Here it is indubitable that the 

 old hereditary tendency is not restrained by different outside influences, 

 but wholly by internal causes, for all the larvae and pupae of many 

 different broods were simultaneously exposed to the same outside influ- 

 ences. If it be asked what significance belongs to the duplication of the 

 winter form, it maybe answered that the species was already dimorphic at 

 the time when it had but one generation a year. Still this explanation 

 may be gainsaid, for such a dimorphism is not elsewhere known, though 

 indeed some species possess a sexual dimorphism in one sex — the female 

 — as in the case of Papilio turnus, which has two forms, but not as is 

 here the case, belonging to both sexes. And therefore perhaps another 

 theory must be advanced. With Irvana we saw the reversion occurring 

 in very different degrees with different individuals ; only rarely it reached 

 the genuine levana form, generally only succeeding in reaching part way, 

 as far as the so-called porima form. Now, it would be at all events 

 astonishing if with Papilio ajax the reversion were every where complete, 

 as exactly here the inclination to revert is so different in different indi- 

 viduals. It might therefore be presumed that one of the two winter 

 forms, indeed telamonides, is nothing else than an incomplete reverting 

 form, answering to por'una with V. levana. Then Walshii only would be 

 the original form of the butterfly, and with this would agree the fact that 

 this variety appears later in the spring than telamonides* Experiments 

 ought to be able to give the explanation. The pupae of the first three 

 generations placed upon ice ought to give for the greater part the telam- 

 onides form, the lesser portion should be Walshii, and only a few, perhaps 

 no individuals should emerge marcellus. And this may be assumed to be 



* There is an error here, Walshii being the earlier form. — E. 



