in PROTECTIVE RESEMBLANCES AMONG ANIMALS 55 



to butterflies or to bees, of beetles to wasps, and of locusts to 

 beetles, has been many times noticed by eminent writers ; 

 but scarcely ever till within the last few years does it appear 

 to have been considered that these resemblances had any 

 special purpose, or were of any direct benefit to the insects 

 themselves. In this respect they were looked upon as 

 accidental, as instances of the " curious analogies " in nature 

 which must be wondered at but which could not be explained. 

 Recently, however, these instances have been greatly multi- 

 plied ; the nature of the resemblances has been more carefully 

 studied, and it has been found that they are often carried out 

 into such details as almost to imply a purpose of deceiving 

 the observer. The phenomena, moreover, have been shown 

 to follow certain definite laws, which again all indicate their 

 dependence on the more general law of the " survival of the 

 fittest," or, " the preservation of favoured races in the struggle 

 for life." It will, perhaps, be as well here to state what these 

 laws or general conclusions are, and then to give some account 

 of the facts which support them. 



The first law is, that in an overwhelming majority of cases 

 of mimicry, the animals (or the groups) which resemble each 

 other inhabit the same country, the same district, and in 

 most cases are to be found together on the very same spot. 



The second law is, that these resemblances are not indis- 

 criminate, but are limited to certain groups, which in every 

 case are abundant in species and individuals, and can often 

 be ascertained to have some special protection. 



The third law is, that the species which resemble or 

 " mimic " these dominant groups are comparatively less 

 abundant in individuals, and are often very rare. 



These laws will be found to hold good in all the cases of 

 true mimicry among various classes of animals to which we 

 have now to call the attention of our readers. 



Mimicry among Lepidoptera 



As it is among butterflies that instances of mimicry are 

 most numerous and most striking, an account of some of the 

 more prominent examples in this group will first be given. 

 There is in South America an extensive family of these 

 insects, the Heliconidae, which are in many respects very 



