82 MIMICRY, AND OTHER PROTECTIVE 



at a longer distance it might be mistaken for one of the 

 uneatable group, and so be passed by and gain another 

 day's life, which might in many cases be sufficient 

 for it to lay a quantity of eggs and leave a numerous 

 progeny, many of which would inherit the peculiarity 

 which had been the safeguard of their parent. 



Now, this hypothetical case is exactly realized in 

 South America. Among the white butterflies forming 

 the family Pieridse (many of which do not greatly 

 differ in appearance from our own cabbage butterflies) 

 is a genus of rather small size (Leptalis), some species 

 of which are white like their allies, while the larger 

 number exactly resemble the Heliconidse in the form 

 and colouring of the wings. It must always be re- 

 membered that these two families are as absolutely dis- 

 tinguished from each other by structural characters as 

 are the carnivora and the ruminants among quadrupeds, 

 and that an entomologist can always distinguish the one 

 from the other by the structure of the feet, just as 

 certainly as a zoologist can tell a bear from a buffalo 

 by the skull or by a tooth. Yet the resemblance of a 

 species of the one family to another species in the other 

 family was often so great, that both Mr. Bates and my- 

 self were many times deceived at the time of capture, 

 and did not discover the distinctness of the two insects 

 till a closer examination detected their essential differ- 

 ences. During his residence of eleven years in the 

 Amazon valley, Mr. Bates found a number of species 

 or varieties of Leptalis, each of which was a more or 

 less exact copy of one of the Heliconidoe of the district 



