TRUE MIMICRY 113 



(PL II, Figs. 1 8 and 19) and Perhybris pyrrha (PL II, Figs. 16 and 17). 

 In the latter of these the male still has, on the upper surface, just 

 the appearance of one of our common Garden-whites, while the female 

 is coloured quite like the Heliconiidaa, but without having lost the 

 form of wing of the Whites. The larger the mimetic company is 

 the greater will be the protection afforded to its palatable mimics, 

 since they will be the more rarely seized by way of experiment. It 

 is, of course, obvious that in this kind of mimicry — that is, in the 

 imitation of an unpalatable and rejected species for protection — it 

 is presupposed as a general postulate that the edible mimics are 

 considerably in the minority, as Darwin showed ; for if it were other- 

 wise their enemies would soon discover that among the apparently 

 unpalatable species there were some which were pleasant to taste. 

 Here, too, the facts bear out the theory, although exceptions can 

 easily be imagined, and do seem to occur. 



This comparative rarity is true of the imitators of the Helico- 

 niidse and their great mimicry ring of unpalatable species, and is very 

 general. Thus, for instance, there is a series of palatable mimics of the 

 beautiful blue Euploece of the Indo-Malayan region (PL III, Figs. 25 

 and 27), but each of these mimics is rare compared with the hosts of the 

 blue unpalatable company, for these immune butterflies also occur in 

 many species, all similar to Euplcea midamus or binotata (PL II, 

 Figs. 1 and 3) ; and the same applies to the mimics of the Indo-Malayan 

 Danaidse. There are a great many Danais species, all of them 

 resembling Danais vulgaris (PL III, Fig. 20), which, when they occur 

 together, form an inedible ring, and this ring is imitated by a whole 

 series of edible species, each of which is comparatively rare. And there 

 are no fewer than six species of Papilio which resemble these Danaids 

 to the point of being easily mistaken for them, while another 

 rare Papilio effectively copies the iridescence of the blue Euplazai— 

 a coloration so unusual in the genus that the species has received the 

 name of Papilio paradoxus. 



But even in single species of butterflies immune through 

 unpalatability there is usually a great abundance of individuals. 

 Thus Danais cltrysippus, which is distributed over the whole of 

 Africa, is a very common butterfly wherever it can live at all ; and 

 in North America, in which country there are only two widely 

 distributed species of Danais, these often occur in enormous numbers. 

 The beautiful large Danais erippus Cramer (PL I, Fig. 8), is 

 distributed over almost all America, and in many places is not only 

 frequent, but occurs in great swarms. Usually it peoples the broad, 

 open stretches of the western prairies of the United States, but when 



