30 Studies in the Theory of Descent. 



quite uninfluenced. In reference to this, the 

 American Papilio Ajax is particularly interesting. 



This butterfly, which is somewhat similar to 

 the European P. Podalirius, appears, wherever it 

 occurs, in three varieties, designated as var. Tela- 

 monides, var. Walshii, and var. Marcellus. The 

 distinguished American entomologist, W. H. Ed- 

 wards, has proved by breeding experiments, that 

 all three forms belong to the same cycle of de- 

 velopment, and in such a manner that the first 

 two appear only in spring, and always come only 

 from hibernating pupae, while the last form, var. 

 Marcellus, appears only in summer, and then in 

 three successive generations. A seasonal dimor- 

 phism thus appears which is combined with 

 ordinary dimorphism, winter and summer forms 

 alternating with each other; but the first appears 

 itself in two forms or varieties, vars. Telamonides 

 and Walshii. If for the present we disregard 

 this complication, and consider these two winter 

 forms as one, we should thus have four generations, 

 of which the first possesses the winter form, and 

 the three succeeding ones have, on the other hand, 

 the summer form, var. Marcellus. 



The peculiarity of this species consists in the 

 fact that in all three summer generations only a 

 portion of the pupae emerge after a short period 

 (fourteen days), whilst another and much smaller 

 portion remains in the pupal state during the 

 whole summer and succeeding winter, first 



