Mimicry 57 



not yet know with certainty what may be the biological significance 

 of the gaily coloured upper surface. 



In general it may be said that mimetic butterflies are com- 

 paratively rare species, but there are exceptions, for instance 

 Limenitis archippus in North America, of which the immune model 

 (Danaida plexippus) also occurs in enormous numbers. 



In another mimicry-category the imitators are often more 

 numerous than the models, namely in the case of the imitation of 

 dangerous insects by harmless species. Bees and wasps are dreaded 

 for their sting, and they are copied by harmless flies of the genera 

 Eristalis and Syrphus, and these mimics often occur in swarms about 

 flowering plants without damage to themselves or to their models; . 

 they are feared and are therefore left unmolested. 



EXPLANATION OF FIGS. 112. 

 Figs. 1 4 represent a Mimicry-ring from Eastern Brazil composed of four immune 



species belonging to three different sub-families and four different genera. 

 Fig. 1. Lycorea halia (Danainae). 

 Fig. 2. Heliconius narcaea (eucrate) (Heliconinae). 

 Fig. 3. Melinaea ethra (Ithomiinae). 

 Fig. 4. Mechanitis lysimnia (Ithomiinae). 

 Figs. 5, 6. Perrhybris pyrrha, male and female, S. American " Whites " (Pierinae). 



The female mimics immune Ithomiines, while the male shows only an indication 



of the mimetic colouring on the under surface. 

 Figs. 7, 8. Dismorphia astynome, male and female, also belonging to the family of 



S. American " whites," and mimicking immune Ithomiines ; a white patch on 



the posterior wing of the male and another on the corresponding surface of the 



under side of the upper wing, remain as traces of the original "white" coloration. 

 Fig. 9. Elymnias phegea, W. Africa, of the sub-family of Satyrines, mimics the 



succeeding species (Fig. 10). 

 Fig. 10. Planema epaea (gea\ an immune West African species belonging to the 



Acraeinae. 



Fig. 11. Danaida genutia, an immune Danaid from India, Burmah, etc. 

 Fig. 12. Elymnias undularis, female, one of the mimics of Fig. 11. 



In regard also to the faithfulness of the copy the facts are quite 

 in harmony with the theory, according to which the resemblance 

 must have arisen and increased by degrees. We can recognise this 

 in many cases, for even now the mimetic species show very varying 

 degrees of resemblance to their immune model. If we compare, for 

 instance, the many different imitators of Danaida chri/sippus we find 

 that, with their brownish-yellow ground-colour, and the position and 

 size, and more or less sharp limitation of their clear marginal spots, 

 they have reached very different degrees of nearness to their model. 

 Or compare the female of Elymnias undularis (Fig. 12) with its 

 model Danaida genutia (Fig. 11) ; there is a general resemblance, but 

 the marking of the Danaida is very roughly imitated in Elymuias. 



