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THE AMEBIC AN NATURALIST [Vol. XLVIII 



B. astyanax the " red-spotted purple " of the southeast- 

 ern states. The hybrid species, B. proserpina, occurs 

 in a zone in which their two faunal areas overlap. 

 In this same group is the common " viceroy " B. ar chip- 

 pus, the range of which roughly covers that of both the 

 other species and extends further westward, touching the 

 Pacific coast in Washington ( Scudder) . The experiments 

 of Edwards, and especially of Field, have shown that 

 these three well-differentiated pure species occupying 

 contiguous, or in respect to ar chip pus overlapping, 

 territory are in some cases at least mutually fertile. 

 B. arthemis and astyanax regularly interbreed in the 

 narrow zone where proserpina occurs. Proserpina, the 

 hybrid, usually shows the general dominance of the 

 astyanax characters (lack of white band). 



From eggs laid by a wild female proserpina Edwards 10 

 secured three arthemis, one proserpina. Field 11 raised 

 from a similar lot of eggs nine proserpina, seven arthe- 

 mis. Presumably in each case the male parent was the 

 recessive arthemis, and hence equal numbers of the two 

 types would be expected. Field has also succeeded in 

 crossing a 2 astyanax with a $ arthemis, and a $ viceroy, 

 archippus, with a J arthemis, the latter pair producing 

 nine males intermediate in color. Specimens of an ap- 

 parent hybrid, intermediate in color between astyanax 

 and archippus, have also occasionally been captured. 



The complete overlapping of the faunal area of archip- 

 pus upon those of the two other species indicates that,' 

 though crossing sometimes occurs, the resulting hybrids 

 are probably usually sterile, though this matter has not 

 yet been thoroughly investigated. Proserpina, however, 

 is a fertile and extraordinarily variable hybrid. In view 

 of its great variability it appears, by the way, not impos- 

 sible that archippus, the red-brown " mimic " of the mon- 

 arch, Anosia plexippus, may have arisen as a mutation 

 from the hybrid proserpina, though the wide-spread 



10 Canadian Entomologist, Vol. IX, 1877. 



11 Psyche, Vol. XVII, No. 3, 1910. 



