1929] On Certain Forms of Common American Butterxies 33 
The autumn brood of these butterflies is invariably of the 
light form. The summer brood is of the dark form, with 
which there are usually to be found a few individuals of the 
light form. 
These forms probably reflect wet spring and dry summer 
conditions acting on the food plants. 
In both species there is a wide difference in the habits 
of the two forms, the dark form tending to remain within a 
restricted area in or near woods and the light form scatter- 
ing widely over open country. This recalls the difference in 
habits of the two forms of Junonia coena. 
Eurymus eurytheme . — From the description of the suc- 
cession of forms of the orange clover butterfly in Texas 
and elsewhere in the southwest it would seem that ariadne 
is a dry form of this species, keewaydin an intermediate 
form, and the deep orange eurytheme with a more or less 
brilliant violet iridescence in the males the extreme wet 
form. 
In the District the earliest individuals to appear are of 
the extreme wet form, eurytheme. In July the keewaydin 
form appears, flying with the other until the end of the 
season and intergrading with it. Early in August the ariadne 
form appears, but it is scarce until after the middle of Sep- 
tember when it becomes frequent, though not very common. 
It flies with the other two until the end of the season in 
October or November. 
About Washington there is noticeable a difference in the 
distribution of these three forms. The deeply colored 
eurytheme is most numerous in the lower areas, especially 
along the river. The most intensely colored and the largest 
individuals are to be found in the wet meadows beyond 
Cabin John. In the higher country the individuals appear 
never to reach such a large size as they do here, while the 
relative proportion of the forms keewaydin and ariadne ap- 
pears to be greater. 
The forms ariadne , keewaydin and eurytheme , which appear 
in seasonal sequence in the southwest, about Washington 
seem to appear in response to very local conditions, perma- 
nent wetness in the boggy pastures and progressive drying 
in the higher areas, which accompany the general trend 
from wet spring to dry autumn. 
