1914,] NATURAL SCIENCES OF PHILADELPHIA. 189 



ancestral elements of L. ohsoleta renders such experiments especially 

 hopeful. ■ 



An experiment made by Edwards and quoted by Scudder (6, p. 278) 

 is also encouraging. The black band of the hind wing of archippus 

 was widened in two butterflies which emerged from pupae subjected 

 to cold, being in one specimen, a female, nearly three times the 

 normal width. 



It is necessary, in conclusion, to point out in a few words some 

 special effects of the Danaine model, D. strigosa. Most prominent 

 among these is the peculiar shade of the ground-color of ohsoleta, 

 «o different from that of arcMppus and floridensis and so strikingly 

 like that of the model. The triangular shape of the discal spots of 

 the fore wing, especially pronounced in those of areas 3 and 4, has 

 evidently been produced in mimicry of the characteristic-looking 

 triangular and diamond-shaped spots of the model. The direction 

 ■of the line of these spots in ohsoleta which has been shown on p. 185 

 to be more ancestral, viz., more like that of arthernis and weide- 

 nneyeri, than in archippus, has doubtless been stereotyped by the 

 model, in which four of the most conspicuous white spots in areas 

 lb, 2, 3, and 4 are parallel with the outer margin of the fore wing. 

 It is also probable, as suggested in a former paper (31, p. 460), that 

 the retention of the white spots representing the discal band on the 

 liind wing upper surface, and it may be added the linear mark in 

 area la of the fore wing, has been aided by "a general likeness " 

 [during flight] "to the pale-streaked hind-wings of strigosa'." Here, 

 too, the relative development of the feature in the female favors 

 a different interpretation; for, as already pointed out (p. 182), 

 the female is slightly the more ancestral and the male the more 

 advanced mimic in this species. The fact that the traces of the 

 l)lack border of the white discal band, which undoubtedly interfere 

 "with the mimetic resemblance, on the whole follow the white spots 

 In the degree of development (p. 182) is also in favor of the sup- 

 position that the entire marking is an ancestral feature which has 

 not yet been got rid of. 



In order to prove that ohsoleta is, as its pattern strongly suggests, 

 ancestral as compared with archippus — that it stands in a position 

 Intermediate between the latter form and the non-mimetic species 

 of Limenitis — arthemis and weidemeyeri — it is necessary- to seek for 

 another line of evidence. 



