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. 1—12. 
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. Zycorea 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. Zlymnias 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 chrysippus 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 Elymnias. 
