BUTTERFLIES OF THE DISTRICT OF COLUMBIA 15 



to be expected in this species. The two forms of Argynnh cyhele 

 seem to correspond to a late-spring and a summer form. The two 

 forms of Polygonia interrogatlonis and P. comma seem to corre- 

 spond to an early-spring and summer form. In both these species 

 occasional individuals occur with the wing shape of the light form 

 but intermediate in color between the extreme light and the dark 

 forms. 



How are these various forms to be interpreted? In the swallow- 

 tails the early-spring form when typically developed has the hair on 

 the body very long, so that the insect appears shaggy, and a tuft of 

 long hairs on the front of the head. Most light-colored butterflies 

 caught in March and early April show a more or less heavy infusca- 

 tion on the lower surface of the hind wing and at the bases of the 

 wings above. Development of long hair on the body and a general 

 infuscation are characteristics of Arctic and Alpine butterflies, and 

 so may reasonably be attributed to the direct effect of cold. But 

 our early-spring forms sometimes lack the long hair, and also may 

 show no trace of any infuscation. This is especially true when they 

 appear in autumn. Furthermore, at the end of the season large 

 individuals of the summer form of the pierids occur with a heavy 

 infuscation. Thus the long hair and the general infuscation, while 

 common attributes of early-spring forms, appear to be secondary 

 features superposed by cold upon a form which occurs normally in 

 cold weather but which is primarily a response to conditions other 

 than those directly produced by cold. 



In the case of Junonia lavinia coenia the differences between the 

 small, light, and active and the large, dark, and inactive forms are 

 essentially the same as those between the so-called dry-season and 

 wet-season forms of the Asiatic Junonia orithya. J. ahnana, and /. 

 ipUta. We seem to be justified, therefore, in considering the bog- 

 living form of the buckeye as a true wet form, corresponding exactly 

 to the wet forms of its Old World relatives. It arises from eggs 

 laid by the dry form, just as they do. It agrees with them in 

 occurring only at a certain season. It differs from them only in 

 being very local, in occurring together with the other forms and with 

 intermediates, and in leaving no descendants. The case is somewhat 

 similar to that of Papilio glaucus canadensh, which is the only form 

 of P. glaucus occurring where it is single brooded, but which in the 

 District appears only as the earliest individuals of the first brood. 



If the large dark and inactive form of the buckeye can be inter- 

 preted as a wet form and the small light active form as a dry form, 

 and if the three forms of this butterfly can be considered as cor- 

 i-esponding to the similar three forms of other District species, it 

 follows that the summer forms of the local species are in reality wet 



