NON-MIMETIC PAEENT OF MIMIC 165 



because of the resemblance between its pattern 

 and that of other species of Limenitis (using the 

 name in the broad sense) from all parts of the 

 circumpolar land-belt, including North America 

 itself. The difference between the pattern of 

 the mimic and that of its non-mimetic parent 

 is enormous — probably as great as that between 

 any two butterflies in the world ; but the steps 

 by which the transition was effected were long 

 ago suggested by S. H. Scudder,' and have 

 recently been worked out in considerable detail 

 by the present writer. ^ 



L. arthemis exhibits the characteristic * White 

 Admiral ' pattern — possessing on the upper sur- 

 face a dark ground-colour with a broad white 

 band crossing both wings, and white markings 

 within the apex of the fore wing. Eeddish or 

 orange spots between the white bands and the 

 margin are found in the hind wings of many 

 individuals, more rarely in the fore wings. These 

 latter markings are of the utmost importance, 

 for, as Scudder long ago pointed out (1. c, 714), 

 they undoubtedly provided the foundation for 

 the change into the mimetic archippus. 



A careful comparison between arthemis and 

 arcJdppus reveals the most conclusive evidence 

 of selection. The one species has become changed 

 into the other precisely as if an artist were to 

 paint the pattern of archippus upon the wings 



^ Butterflies of the Eastern United States and Canada, Cambridge, 

 Mass. (1889), 278, 714. 

 " Trans. Ent. Soc. Lond. (1908), 454-60. 



