PHILENOE AN AMERICAN MODEL 181 



characters. Rothschild and Jordan state that 

 every species can be recognized as American by 

 the examination of a single joint of one leg, and 

 they are therefore justified in concluding that all 

 the New World species were derived from a single 

 ancestor possessing this character. There is no 

 suflScient evidence that any of the numerous 

 patterns are ancestral as compared with the others, 

 although it is tolerably safe to conclude that the 

 presence of hind-wing ' tails ' is primitive as com- 

 pared with their absence. Following this indica- 

 tion, we find that as a general rule the specialized 

 and modern forms are predominant nearer to the 

 Equator, the comparatively ancestral tailed forms 

 occurring in latitudes more remote from it both 

 north and south. 



Ph. philenor is a ' tailed ' form, although its sub- 

 species orsua in the Tres Marias Islands is nearly 

 tailless. It is probably an intruder into North 

 America from the tropics of the same Continent. 

 It is well known to possess the characteristics 

 of distasteful species — gregarious larvae, tenacity 

 of life, and a strong, disagreeable scent. 



THE THREE PAPILIO MIMICS OF PH. PHILENOR 

 IN NORTH AMERICA 



The three swallow-tail mimics oi pMIenor belong 

 to separate groups of Haase's section Papilio. All 

 of them range from the Atlantic to the Mississippi 

 basin. 



