346 THE PLACE OF MIMICRY 



closer between the species exhibiting a strong Primary 

 Mimicry than between those exhibiting a weaker resem- 

 blance to the central model. This suggests that the 

 Secondary Resemblance is of permanent value, and not a 

 mere phase which will ultimately be lost in the Primary 

 Resemblance. 1 



The very best example of Secondary Mimicry I have 

 ever seen was shown to me, when a young man, by the 

 late Professor Westwood. He asked what I thought of 

 two small transparent - winged, black-marked South 

 American Lepidoptera with hind wings margined in red 

 and black. Did I think they were the same species ? 

 To my inexperienced eyes, attracted by the pattern, 

 they looked absolutely alike. Did I think they were 

 the same genus or family, and finally was it possible that 

 one was a butterfly and the other a moth ? And so it 

 proved to be ! The model was a small Erycinid 

 butterfly, itself a mimic of an Ithomiine ; the mimic a 

 day-flying moth of the same size. In this remarkable 

 case, the Secondary Mimicry was far closer than the 

 Primary. Not only is the Erycinid shown to be 

 specially protected by acting as a model, but the moth 

 itself was a member of a conspicuous distasteful group. 



10. Further Indirect Evidence Supporting a Miillerian 

 or Synaposematic Interpretation. — The following generali- 

 zations, first published in 1902, 2 support the Miillerian 

 interpretation of a large number of examples previously 

 explained upon the Batesian Hypothesis. 



(a) The fact that mimetic likeness tends to run in 

 genera or larger groups and is rarely seen in single 

 isolated species. It is more reasonable to explain this 

 fact by the hypothesis of some special defence common 

 to the group in question, than by supposing that all 

 or almost all of its members are compelled to shelter 

 themselves under a deceptive likeness to other dominant 

 and specially defended forms. 



(6) In many cases it is known that the mimetic groups 

 are large and dominant, and the individuals of many of 



1 Trans. Ent. Soc, Lond., 1902, p. 485. 



2 Trans. Eni. Soc, Lond., 1902, pp. 500-2. 



