292 THE BUTTERFLIES OF NEW ENGLAND. 



think the figure [a colored drawing] is of proserpina ; the white band is 

 unusually broad on the upper surface." This single example, due possibly to 

 the union of an arthemis with a proserpina which had followed the coast 

 northeastward at an average rate of a dozen miles a day, should not be 

 considered as in any sense an impossibility, nor is it necessary to assume 

 so much as to suppose it the result of a single season's accident. It is not 

 at all improbable that ursula may yet be found as far as Mt. Desert, and 

 that colonies of proserpina are now living along the whole coast of Maine ; 

 negative evidence from a region where collectors are so few and sparsely 

 scattered, has but little value. Nor is it at all improbable that the speci- 

 men in question may not be a genuine arthemis, varying (possibly by 

 reversion) toward an allied species of similar ancestry. 



The second objection has no weight whatever, especially if we look 

 upon astyanax (as the last suggestion above possibly indicates), as nearer 

 the ancestral form from which both descended ; for where hybridity and a 

 tendency to reversion combine, there we should look for an easier min- 

 gling of these characters, and the "northern form" of astyanax would 

 result as a further approach toward the southern, by the union of proser- 

 pina with the latter and would be perpetuated in the northern part of the 

 range of astyanax, by the constantly renewed supply of new parents ; that 

 is, this form, very likely destined to eventual distinction, would not disap- 

 pear by amalgamation with the true stock, receiving as it would, a con- 

 stant infusion of new blood. The occurrence, therefore, of a "northern 

 form" of astyanax, is rather an argument in favor of, than opposed to the 

 hybrid theory of the status of proserpina. 



In addition to this it has been noted by at least one observer, Mr. R. 

 M. Grey of Kenwood, N. Y., that when flying in a restricted locality 

 where arthemis is found and no ursula, proserpina varies towards its com- 

 panion ; while in the lower county a few miles distant where the opposite 

 condition prevails, the variation is in the reverse condition. I quote his 

 words, not written with the purpose of maintaining the thesis here upheld, 

 but of the unity of all the species of Basilarchia. 



Near the Hudson River I find ursula and proserpina in close association, each par- 

 taking of the markings of the other, evidently one brood, alighting on the same heap 

 of pomace; expansion of -wings three to three and a half inches. About six miles 

 from the river ursula and proserpina are equally abundant, with a few arthemis and 

 rarely a disippus. Expansion of the wings of the four about two and a half inches ; 

 all found in one glade. From this to the highest tables of the Helderberg Hills, ursula 

 gradually disappears and only proserpina and arthemis are found, the latter most 

 abundant. In the low lands disippus, ursula and proserpina are only found; in inter- 

 mediate brolven lands ursula, proserpina and arthemis are chiefly found ; at the highest 

 altitudes only proserpina and arthemis are found, and examinations of many examples 

 from the different localities show that these forms approach each other very closely 

 (Can. ent. , xi : 10). 



Distribution (19 : 4) . As stated above, this form of Basilarchia is found 



