On the Seasonal Dimorphism of Butterflies. 3 



formerly been distinguished as Plebeius (Lycczna) 

 Polysperchon and P. Amyntas, were merely winter 

 and summer generations of the same species ; and 

 that excellent Lepidopterist, Dr. Staudinger, proved 

 the same 2 with species belonging to the family of 

 the ' Whites/ Euchloe Belia Esp. and E. Ausonia 

 Hlib., which are found in the Mediterranean 

 countries. 



The instances are not numerous, however, in 

 which the difference between the winter and sum- 

 mer forms of a species is so great as to cause them 

 to be treated of in systematic work as distinct 

 species. I know of only five of these cases. 

 Lesser differences, having the systematic value of 

 varieties, occur much more frequently. Thus, for 

 instance, seasonal dimorphism has been proved to 

 exist among many of our commonest butterflies 

 belonging to the family of the ' Whites,' but the 

 difference in their colour and marking can only be 

 detected after some attention ; while with other 

 species, as for instance with the commonest of our 

 small 'Blues/ Plebeius Alexis (j=. Icarus, Rott.), 

 the difference is so slight that even the initiated 

 must examine closely in order to recognize it. 

 Indeed whole series of species might easily be 

 grouped so as to show the transition from complete 

 similarity of both generations, through scarcely 



2 " Die Arten der Lepidopteren-feattung Ino Leach, nebst 

 einigen Vorbemerkungen iiber Local varietaten." Stett. ent. 

 Zeit. 1862. Vol. xxiii. p. 342. 



B 2 



