312 Mimetic Analogy. 



departed from the proper normal form of the genus Leptalis, 

 which is shown at Figure 1, representing L. Nehemia ; whilst 

 the Heliconidge figured, belonging to the genera Ithomia and 

 Methona, are the imitated, because they resemble their nearest 

 allies. Hence we regard Leptalis Theonoe, var. Leuconoe, Fig. 

 2, as imitating Ithomia Ilerdina, Fig. 2a; Leptalis Orise, 

 Fig 3, as imitating Methona Psidii, Fig. 3a; and Leptalis Theonoe, 

 Fig. 4, as imitating Ithomia Flora, Fig. 4a. 



These resemblances are sufficiently striking when seen in 

 the cabinet, or even as represented in the accurate plate which 

 illustrates this article. But it is only when the animals are 

 seen in the natural state that the palpable intentional imitation 

 is seen in its full force ; for those features of the portrait, says 

 Mr. Bates, are most attended to by nature which produce the 

 most effective deception when the insects are seen alive. 



The next point to be considered is the useful end served by 

 this mimetic analogy. In the majority of cases the motive is 

 evident — it is protection against natural enemies, either by 

 concealment or disguise. Those animals that resemble the 

 objects with which they are surrounded are protected from the 

 observation of others that prey upon them. The ground feeding 

 birds, such as the partridge and snipe, the hare amidst the dried 

 leaves, the ptarmigan in the snow, are all well known instances 

 of the advantage of the assimilation of colour to that of surround- 

 ing objects. In the case of the South American butterflies the 

 imitation is obviously for the purpose of disguise rather than 

 of concealment. The Heliconidas are a numerous and flourish- 

 ing group: although slow flying, they are never persecuted by 

 birds or dragon-flies, to which it might be supposed they 

 would be an easy prey; nor when at rest on the leaves are they 

 molested by lizards or predaceous flies, which constantly devour 

 butterflies of other families. They appear to owe this immunity 

 from persecution to their offensive odour, which renders them 

 unpalatable to the enemies of insects. Even when set out to 

 dry in the cabinet of the collector, they are less liable to be 

 attacked by vermin than other specimens. 



Now it is obvious that the more closely an inodorous but- 

 terfly of another species, resembles one of the bad-smelling and 

 offensive Heliconidas, the less likely will it be to be preyed upon 

 by its natural enemies. Hence the imitation of the genera 

 Ithomia and Methona by the persecuted insects of the genus 

 Leptalis. 



The mode in which this remarkable imitation is brought 

 about has now to be considered. Some naturalists maintain 

 that the resemblances existed from the Creation ; but the diffi- 

 culties in this view of the case are numerous. One of the 

 strongest arises from the fact, that in those cases where a local 



