493 
[Packard. 
deeper and more uniform ground color, more distinct in the sum- 
mer form. As the lines and dots vary somewhat in my specimens 
of the more common winter form ( arcuata ), my material will not 
allow me to say that there are any other differences than that of 
the ground color, although the apex of the fore wings is more pro- 
duced in the summer form. 
In this species, then, temperature, i. e., the hibernation of the 
pupae of the second brood, seems to be the main factor in causing 
the variation in the two broods of moths, and this results in a 
slight change of form of the wings, in a deepening of the colors of 
the entire moth, and probably a diminution in its size. 
Seasonal dimorphism in Dryopteris rosea Walk. — Mr. Elliot at 
the same time told me that he had raised D. rosea and D. irrorata 
Pack., from caterpillars feeding on the birch and Viburnum, and 
that the larvae of both forms are “ exactly the same in markings, 
shape and habits.” He also told me that D. irrorata comes from 
the second brood of D. rosea , adding that D. rosea varies a good 
deal, some females being nearly all yellow. If these results ob- 
tained by so acute, careful and experienced an observer should be 
confirmed, then irrorata may be regarded as the summer form of 
D. rosea. It should be observed that Mr. R. Thaxter has collected 
D. irrorata in Newfoundland. Walker’s D. marginata is a yellow 
variety of D. rosea. 
Drepana siculifer Pack., probably a climatic variety of D. arcu- 
ata. — So far as I can judge from a single female received from Cal- 
ifornia, this form appears to be only a climatic variety of our east- 
ern D. arcuata , of which I have several males and a female. The 
Californian form is larger 1 than the eastern ones. I have a male 
of arcuata which differs in no important respect from the Cali- 
fornian female, except in the size of two of the discal dots, the 
outer two being very large in the Californian form. I should 
say, however, that the specimen now before me differs considerably 
from my description, and that I cannot at present examine my 
type. But, however this may be, my second Californian female is 
evidently not different specifically from the eastern arcuata and 
follows the law of climatic variation referred to in my “ Mono- 
graph of Georaetrid Moths” (p. 587), where it is stated that thir- 
ty-one species of moths, mostly Geometrids, have larger and longer 
wings on the Pacific coast than Atlantic coast individuals. 
1 The length of the fore wing of my Californian female is 21 mm. ; that of my largest 
eastern female 18 mm. 
