40 NATURE STUDIES. 



the birds. But now comes the most curious phase of 

 this history. Another and distinct family of butter- 

 flies, known as the Leptalidce, allied to the common 

 white cabbage butterfly, and removed from the Heli- 

 cons, also possesses representatives in South America. 

 There are no points of agreement between the Lep- 

 talides and the Helicons, save, indeed, that both are 

 butterflies. Furthermore, the Leptalides are entirely 

 destitute of the nauseous odour and of the strong 

 taste of the Helicons, and in respect of their more 

 agreeable presence, should become a prominent 

 article as do other butterflies in the bill of fare 

 of the birds. Yet, strangely enough, the Leptalides 

 escape persecution ; and the reason is not far to seek 

 or difficult to find. When they are carefully examined, 

 certain species of the Leptalides are seen to be exact 

 facsimiles, in colour and appearance, of the stinking 

 Helicons ! Naturalists at first classed both as He- 

 licons, until a closer examination showed the differ- 

 ence between these butterflies, and likewise proved 

 that the Leptalides had thus "mimicked" in the 

 plainest possible manner the colours of their strong- 

 smelling neighbours. Nor are the colours alone 

 imitated. The very shape of the Helicon's wings is 

 reproduced in those of the Leptalides, and the 

 " feelers " likewise mimic those of the former group. 

 Again, special forms of Leptalides " mimic" special 

 forms of Helicons. The flight has become of similar 

 character in both species, and the habits have been 

 also slavishly copied. 



