84 MIMICRY, AND OTHER PROTECTIVE 
possibility of their being found out by their enemies. 
It is also very remarkable that in almost every case the 
particular Ithomias and other species of Heliconide 
which they resemble, are noted as being Very common 
species, swarming in individuals, and found over a 
wide range of country. This indicates antiquity and 
permanence in the species, and is exactly the condition 
most essential both to aid in the development of the 
resemblance, and to increase its utility. 
But the Leptalides are not the only insects who have 
prolonged their existence by imitating the great pro- 
tected group of Heliconide ;—a genus of quite another 
family of most lovely small American butterflies, the 
Erycinide, and three genera of diurnal moths, also 
present species which often mimic the same dominant 
forms, so that some, as Ithomia ilerdina of St. Paulo, 
for instance, have flying with them a few individuals 
of three widely different insects, which are yet dis- 
guised with exactly tle same form, colour, and mark- | 
ings, so as to be quite undistinguishable when upon the 
wing. Again, the Heliconide are not the only group 
that are imitated, although they are the most frequent ; 
models. The black and red group of South American 
Papilios, and the handsome Erycinian genus Stalachtis, _ 
have also a few who copy them; but this fact offers no 
difficulty, since these two groups are almost as domi- 
nant as the Heliconide. They both fly very slowly, 
they are both conspicuously coloured, and they both 
abound in individuals ; so that there is every reason to ' 
believe that they possess a protection of a similar kind 
