1909] Mimicry in the Butterflies of North America 217 



I have dwelt upon the changes undergone by the white band 

 as an example of the way in which the new markings have been 

 carved out of the old. The changes in the elaborate marginal 

 pattern would have been equally convincing as evidence for a 

 gradual and "continuous" transformation. 



The Modification of the LniENiTis Mimic of Danaida 



PLEXIPPUS INTO A MiMIC OF D. BERENICE IN FLORIDA. 



Danaida plexippus occurs together with D. herenice in Florida, 

 but the latter far outnumbers the former, and the modification of 

 Limenitis archippus into the (onn floridensis, Strecker {=cros, 

 Edw.) is probably entirely due to the predominance of one model 

 over the other. Data for determining the exact proportions in 

 various localities would be of high interest. There is no reason 

 for believing that berenice is in any way more or less distasteful 

 than plexippus, but its abundance makes it a more conspicuous 

 feature in the environment. 



It is evident that the change has been of the kind expressed 

 in the above heading; for, as has been already implied in pp. 213-14, 

 traces of the former IMimicry of plexippus persist in floridensis 

 and tend to detract from the resemblance more recently developed. 

 This is especially the case with the conspicuously blackened veins 

 of archippus, which are so important a feature in the likeness to 

 plexippils. These, although obscured by the general darkening, 

 are still recognizable in floridensis, diminishing its resemblance 

 to herenice on the upper surface of both wings and on the under 

 surface of the fore wing. Inasmuch as the details have been 

 recently published elsewhere,^* I will only dwell on one further 

 point in the resemblance of floridensis to herenice — and that be- 

 cause the extensive observation of large numbers of specimens is 

 greatly needed. I spoke on pp. 2 r5-i6 of the persistent traces of 

 the white band on the hind-wing under surface in many indivi- 

 duals of L. archippus. These are ancestral features, diminishing 

 the mimetic resemblance to D. plexippus. But in D. herenice 

 there are conspicuous white spots towards the centre of the hind- 

 wing under surface, and these, at any rate upon the wing, would 

 bear some resemblance to the ancestral spots of the Limenitis 

 mimic. Now in my very limited experience of floridensis these 

 spots were sometimes exceptionally developed and, outlined with 

 black on their inner edges, were certainly far more distinct and 



IS Trans. Ent. Soc. Land. (1908), 460, 4G1. See also Scudder, 1. c. 718. 



