Butterflies 221 



Professor J. H. Gerould carried on some extensive experi- 

 ments in hybridizing E. eurytheme (from Arizona) with E. philo- 

 dice (from New Hampshire). The offspring were yellow flushed 

 with orange, and this was even the case when he used white 

 females of E. eurytheme, showing that the latter carried the factor 

 for orange in the germ-plasm. Many years ago, W. H. Edwards 

 proposed as species what he called ariadne and heewaydin. The 

 form ariadne is just like Gerould's hybrids, and flies where the 

 orange and yellow forms approach each other or meet. The one 

 called \eewaydin is larger and more strongly suffused with orange, 

 being intermediate between ariadne and the large brilliant orange 

 form which Boisduval named amphidusa. We may suspect that 

 these orange-flushed insects had their origin as hybrids, or are 

 derived from hybrid stock, but they occur not only along the 

 eastern border of the range of E. eurytheme, but also across the 

 western country to the Pacific. It appears that ariadne is the 

 spring form, not genetically distinct from k^waydin. In Custer 

 County, Colorado, I found a race which I named intermedia, 

 larger than heevoaydin, expanse of wings in female over two inches, 

 color of wings pale sulphur, with distinct orange patches on the 

 front pair, much as in ariadne, but the wings much suffused with 

 black scales near their bases; under side of hind wings pale green- 

 ish yellow, not ochreous as in keewaydin, but without the gray- 

 ish appearance of ariadne. Finally, the investigations of Verity, 

 Barnes and McDunnough have shown that the original eurytheme 

 of Boisduval was orange-flushed, and was essentially identical 

 with ariadne. Boisduval was so impressed by the differences 

 between this and the rich orange form that he called the latter a 

 separate species, amphidusa. Both names were given in 1852, 

 on the same page, but all agree in now employing E. eurytheme as 

 the name of the collective species. 



We may now recapitulate by saying that there is a yellow 

 species in the East and an orange species or race in the West. 

 Both produce white females, but never white males. The yellow 

 species never gives rise to orange specimens, but the orange one 

 produces yellow ones, not always easily separated from the 

 Eastern E. philodice. But over a large range, from the Mississippi 

 to the Pacific, are found orange-flushed specimens, closely simu- 

 lating, at least, the hybrids raised by Gerould. In addition, there 



