igoy] Mimicry in the Butterflies of North America 22 



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The female of Papilio polyxenes asterius (Cr.) belonging to the 

 Machaon Group mimics philenor on both surfaces, the male on 

 the under surface alone, except at Guerrero, Mexico, where a form 

 (ampliata) mimetic on the upper surface is transitional into the 

 ordinary male. 



Papilio glaucus glaiiciis (L.) belongs to the Glaucus Group, 

 next but one to the group containing asteriiisr^ The female is 

 dimorphic, one form resembling the male and the other, the ttirniis 

 form, mimetic of philenor (L.), becoming commoner in the south- 

 ern part of the range. In the closely allied sub-species P. glau- 

 cus canadensis (Rothsch. and Jord.), the mimetic female form is 

 unknown. 



Papilio troilus troilus (L.) belongs to the next succeeding 

 Troilus Group, allied to the tropical and highly mimetic An- 

 CHisiADEs Group, with gregarious larvae. Both male and female 

 of troihts mimic philenor on both wing surfaces. 



The most remarkable fact about these three mimics is not 

 their moderate resemblance to the primary model philenor, but 

 their extraordinary likeness to one another. Upon the wing or 

 at rest at a little distance they would be indistinguishable, -and 

 even in the cabinet they may be easily confused. It is to be 

 expected that the species of allied groups, with patterns converg- 

 ing towards that of a single model, and approaching it by varia- 

 tions which tend to be produced in the section to which they 

 belong, should incidentally approach one another. But the 

 strong likeness between the mimetic forms of troilus asterius, and 

 glaucus seems to require something more than this, and supports 

 the conclusion that there is secondary Mimicry between the mim- 

 ics themselves. It is not necessary to repeat here the details of 

 these secondary resemblances," and as a matter of fact the like- 

 ness itself is stronger than might be inferred from a consideration 

 of the details themselves. It is necessary to see it in order to 

 appreciate it. 



It is probable that troilus, mimetic in both sexes, is the oldest 

 mimic; asterius, non-mimetic on the upper surface of the male or 

 with very rough incipient Mimicry, the next to appear; and glau- 

 cus, mimetic in only one form of the female, the youngest. These 

 conclusions as to relative age are on the whole supported by the 

 relative strength of the detailed resemblances to philenor in the 

 three mimics. 



-" The species is commonly called P. turnns and its mimetic female the 

 glaucus form. 1 follow Rothschild and Jordan in transposing these names. 

 -• See Trans. Ent. Soc. Land. (1908), 467-471. 



