Slides of the Genus Limcnitis. 459 



in many individuals of archifpus have lost their original 

 form and gained a rounded shape. They often tend, as in 

 the model, to be more strongly developed in the anal part 

 of the series. Clear evidence of selection is seen in the 

 relation between the degree of development of the black, 

 white-marked marginal pattern in fore- and hind-wing of 

 arthemis and aorhippus respectively. In arthemis this 

 pattern is far more developed in the hind-wing than the 

 fore, a condition reversed in archippus in accordance with 

 the pattern of its model. A sickle-like curve is developed 

 within the apex of the fore-wing in the same manner but 

 not so fully as on the under surface. 



The black outer border of the white discal band persists 

 but is less heavy than on the under side. As on the latter 

 surface it seriously interferes with the likeness to Anosia 

 on the hind-wing, but enters into the mimetic pattern on 

 the fore. Vestiges of the white discal band were not found 

 on the upper surface of the hind-wing in any of the 

 numerous specimens I have examined (although occurring 

 in the form hulsti, Edw.) ; nor was the black band entirely 

 wanting from any. A variety without this latter marking 

 is however known and has been described as piseicdodor- 

 ippus, Strecker. The type of this form exists in Dr. W. J. 

 Holland's collection (" Butterfly Book," New York, 1899, 

 p. 185). On the fore-wing, vestiges of the white band 

 persist and enter into the mimetic pattern, but they are 

 far more reduced than on the under surface, in correspond- 

 ence with the fact that many of the orange apical spots 

 on the upper surface of the model are represented by white 

 on its under surface. 



The triangular pale spot in the cell of the fore-wing is 

 usually represented on the upper surface by its black border 

 only, but in a considerable proportion of individuals the 

 white centre persists in a conspicuous form. In many indi- 

 viduals of the ancestral arthemis the same marking appears 

 on the upper surface as a white point, generally very 

 minute and often developed unequally on the two sides. 



d. The tvhite spots on Body and Appendages of Limenitis 

 arehippius. — There appears to be great variation in arthemis 

 in the development of these pale spots and markings, but 

 there is no doubt about their great increase in size and 

 brilliancy in archippus and conversely their great reduction 

 in astyanax. Pale spots corresponding to the brilliant 

 white marks of archippus are always to be found in some 



