in PROTECTIVE RESEMBLANCES AMONG ANIMALS 61 



advantage to other insects to be mistaken for them. There 

 is also another extraordinary fact that we are not yet in a 

 position clearly to comprehend : some groups of the Heli- 

 conidae themselves mimic other groups. Species of Heliconia 

 mimic Mechanitis, and every species of Napeogenes mimics 

 some other Heliconideous butterfly. 1 This would seem to 

 indicate that the distasteful secretion is not produced alike 

 by all members of the family, and that where it is deficient 

 protective imitation comes into play. It is this, perhaps, 

 that has caused such a general resemblance among the Heli- 

 conidse, such a uniformity of type with great diversity of 

 colouring, since any aberration causing an insect to cease to 

 look like one of the family would inevitably lead to its being 

 attacked, wounded, and exterminated, even although it was 

 not eatable. 



In other parts of the world an exactly parallel series of 

 facts have been observed. The Danaidse and the Acrseidse of 

 the Old World tropics form in fact one great group with the 

 Heliconidse. They have the same general form, structure, 

 and habits ; they possess the same protective odour, and are 

 equally abundant in individuals, although not so varied in 

 colour, blue and white spots on a black ground being the 

 most general pattern. The insects which mimic these are 

 chiefly Papilios and Diadema, a genus allied to our peacock 

 and tortoiseshell butterflies. In tropical Africa there is a 

 peculiar group of the genus Danais, characterised by dark- 

 brown and bluish-white colours, arranged in bands or stripes. 

 One of these, Danais niavius, is exactly imitated both by 

 Papilio hippocoon and by Diadema anthedon ; another, Danais 

 echeria, by Papilio cenea ; and in Natal a variety of the 

 Danais is found having a white spot at the tip of wings, 

 accompanied by a variety of the Papilio bearing a correspond- 

 ing white spot. Acrsea gea is copied in its very peculiar 

 style of coloration by the female of Papilio cynorta, by 

 Panopsea hirce, and by the female of Elymnias phegea. Acraea 

 euryta of Calabar has a female variety of Panopea hirce from 

 the same place which exactly copies it ; and Mr. Trimen, in 

 his paper on " Mimetic Analogies among African Butterflies," 



1 A satisfactory explanation of this phenomenon has now been found. See 

 Darwinism, p. 252. 



