1286 THE BUTTERFLIES OF NEW ENGLAND. 



black upon the upper surface ; and the other, the male of Cyaniris 

 pseudargiolus, in which a similar change is general in the same southern 

 region, but in this case affecting the male sex. These two cases, belong- 

 ing to different families, though occurring in butterflies of similar range in 

 a similarly restricted district, have no other points in common. First, 

 Jasoniades is a vellow butterfly, striped with black, in which both sexes 

 are normally alike, but where in the melanic form the yellow is partially 

 or wholly subdued, the wing becoming totally black above. In the other 

 the sexes already differ in color, the female being paler than the male and 

 having a broad brown margin, while the male is almost or absolutely uni- 

 form blue above ; in the melanic male, however, this blue is almost en- 

 tirely changed to a dark brown or to a shade similar to that bordering the 

 wings of the female. Besides this, the melanic female of Cyaniris appears 

 only in the spring brood, and here comprises all the members of that 

 brood, at least in the southern portion of its distribution, while there is no 

 seasonal restriction in Jasoniades. There are two other instances of this me- 

 lanism among our New England buttei-flies, Atrytone zabulon and Erynnis 

 attains, where the upper surface of the female is affected in certain instances. 

 These again differ from the others, first in the imperfection of the melanism 

 and second in there being no restriction to the range of the melanic form, 

 appearing as far as we know wherever the normal form appears and in about 

 ecpial quantities ; similar examples appear in allied Pamphilidi. 



Instances of albinism are confined, so far as we yet know, to the Rhod- 

 oceridi ( where white is a prevailing color in an allied tribe) and to the 

 female sex. It is familiar to all entomologists, especially in the genus 

 Eurymus. In some instances all the females are albinic ; in others only 

 a portion of them, but not restricted as to geographic range, though in 

 polymorphic species relatively far more frequent in later than in earlier 

 broods, but known to occur in all. It is found in all the Rhodoceridi men- 

 tioned in the body of the present work with the sole exception of Calli- 

 dryas. Among the Eurymi it is far more common in the species of the 

 subarctic and subalpine regions than in those found in lower levels or lati- 

 tudes ; and only here does it ever include all the females. 



How to explain these phenomena is exceedingly difficult. The moment 

 one begins to speculate, some fact appears which altogether upsets any 

 theory he may form on the subject. Thus while this is plainly a form of 

 colorational antigeny, which I formerly inferred was a departure on the 

 part of the female from the normal coloring of the sex, it immediately ap- 

 peared that in the case of our blue butterfly, it was the male and not tlie 

 female that was melanic, in striking opposition to all the cases we other- 

 wise know of melanic or albinic antigeny. How should this be explained? 



If melanism or albinism were confined altogether to females, we might 

 look upon it as a form of protective coloring similar to some instances we 



