ARCTIC BUTTERFLIES CLARK 293 



In this connection the occurrence of the broad submarginal band 

 on the under side of the fore wings in the Arctic yellow swallowtails 

 as well as in all the yellow swallowtails of our more or less arid 

 western country is of interest. Still more interesting is the occur- 

 rence of the same band in the very small yellow swallowtails of 

 early spring in the vicinity of Washington, together with the practi- 

 cally tailless form {acauda) of the blue swallowtail {Papilio 'phil- 

 enor)w\\\Q\\ is otherwise known only from Mexico and the southern 

 portion of New Mexico. These occur, however, only if the warm 

 weather of early spring follows immediately after very cold weather ; 

 if the passage of winter into summer is gradual they do not appear. 

 All of the butterflies living about Washington that have both a " wet " 

 and a " dry " form occur in early spring only in the latter. Such 

 are the buckeye {Junonia coenia), the painted lady {Vanessa ca7'dui), 

 the angle wings (Polygonia) and the orange clover butterflies (C olios 

 eury theme) . In the case of the buckeye and the painted lady the 

 " wet " form together with the " dry •' is found in the late autumn, 

 but only the " dry " lives through the winter. Among the most char- 

 acteristics of the Arctic butterflies are the clover butterflies [C olios) ^ 

 the bog fritillaries {Brenthis) , the little blues {Lycaenidae) ^ and the 

 satyrids {Scttyridae) . In the arid regions of the Tropics we find as 

 characteristic butterflies close relatives of the clover butterflies (espe- 

 cially CatopsUia), various little blues, and certain satyrids. Further- 

 more, some of the bog fritillaries live in regions that for a large por- 

 tion of the year are extremely dry. 



Professor Griggs has pointed out that the floral characteristics of 

 the Arctic are chiefly negative, owing to the absence from northern 

 lands of species occurring in southern latitudes. This is quite as 

 true of Arctic butterflies as it is of Arctic plants. 



Although all Arctic plants are more or less dwarfed and usually 

 rise but little above the ground, they exhibit no structural peculiari- 

 ties that differentiate them from allied species farther south. Among 

 the butterflies all the Arctic species or varieties are more or less 

 dwarfed, but they show no structural differences as compared with 

 others from other regions. In addition to being dw^arfed they are 

 more or less suffused with black or blackish, at least on the under side, 

 and the head and body are very hairy. These features are shared 

 with early spring butterflies from regions much farther south, es- 

 pecially in eastern North America. One of the clover butterflies in 

 the vicinity of Washington {Colias eury theme) in early spring ap- 

 pears in a small and very pale form with only a slight trace of orange 

 on the upper side, and dark greenish on the under side of the hind 

 wings. In autumn, if the season be hot and dry, this small light 

 form reappears, but without the dark suffusion on the under side. 



