RESEMBLANCES AMONG ANIMALS. 75 



semblance that deceives. As this kind of resemblance 

 has the same effect as voluntary imitation or mimicry, 

 and as we have no word that expresses the required 

 meaning, " mimicry " was adopted by Mr. Bates (who 

 was the first to explain the facts), and has led to 

 some misunderstanding ; but there need be none, if 

 it is remembered that both a mimicry " and a imita- 

 tion" are used in a metaphorical sense, as implying 

 that close external likeness which causes things un- 

 like in structure to be mistaken for each other. 



Mimicry. 



It has been long known to entomologists that certain 

 insects bear a strange external resemblance to others 

 belonging to distinct genera, families, or even orders, 

 and with which they have no real affinity whatever. 

 The fact, however, appears to have been generally con- 

 sidered as dependent upon some unknown law of " ana- 

 logy " some " system of nature," or "general plan," 

 which had guided the Creator in designing the myriads 

 of insect forms, and which we could never hope to 

 understand. In only one case does it appear that the 

 resemblance was thought to be useful, and to have been 

 designed as a means to a definite and intelligible 

 purpose. The flies of the genus Volucella enter the 

 nests of bees to deposit their eggs, so that their larvae 

 may feed upon the larvse of the bees, and these flies 

 are each wonderfully like the bee on which it is 

 parasitic. Kirby and Spence believed that this resem- 

 blance or " mimicry " was for the express purpose of 



