﻿THE ENTOMOLOGICAL MAGAZINE, Vol. 111. Pt. I. 



tion of variation in the number of spots tending always to the formation 

 of new spot, and never to the contrary. 



Since there would be no species, in wliich such spots as those of the 

 interspace II， or VI of the fore wing, or the interspace I b, VII (under 

 surface) or IV, V, VI (upper suiffice) of the hind wing are nornially 

 formed among the genus Ypthima of Japiiii and of the adjacent terri- 

 tories, the appearance of such spots probably luis the significance of 

 progressive variation not retrogressive. The fact that the size of the 

 spots on the under surface of the hind wing is usually reduced in the 

 spring generation reminds us of the difference between the wet- and the 

 dry-season forms of many tropical species of this subfamily. It has been 

 known that these two forms differ distinctly from each other in size and 

 definition of the eye-spots on the under surface, the dry forms having 

 always smaller or less conspicuous spots than the wet forms. Moreover 

 it has been stated that these two forms usually differ from each other in 

 several respects besides the definition of the eye-spots, e.g., the expansion 

 of the wings, the patterns on the under surface. In the present material 

 too, the spring generation has several other characteristics : tlie ground 

 color of the upper surface of the wings is paler ； the discal and siibterminal 

 fascinae on the under surface of the fore wings are less conspicuous : the 

 under surface is more densely straitea ； the under surface of the males is 

 more deeply suffused with yellow; and the size of the wings is larger 

 than the summer generations. ($) Most of these points are practically 

 identical with what Bingham(3) has mentioned to be the characteristics 

 in which the two seasonal forms of the Indian Y. philomera are dis - 

 tinguished from each other. It is accordingly quite possible that the 

 reductive variation of the eye-spats in the spring generation of the Japa- 

 nese variety is due to the same cause, and also has the same ethological 

 meaning as in the tropical original species, althoueh it appears to be 

 much less marked. The reduction on the under surface by no means 

 implies the coincident diminution of the size of the spots on the upper 

 surface. In many cases, variation reveals itself quite contrary on the 

 Opposite surface ； as for instance, Mycalesis mineus and M. perseus 

 which I have secured from Formosa tend to be provided with the eye- 

 spots on the upper surface more numerous and more conspicuous in the 



