2o() Annals Entomological Society of America [Vol.11, 



ordinarily akin to the methods of Artificial Selection. Indeed a 

 very fascinating and promising line of investigation in a suitable 

 locality would be the attempt to initiate or improve a mimetic 

 likeness by means of Artificial Selection. 



Mimetic resemblances are of two kinds, respectively inter- 

 preted by two well-known hypotheses, both based on the theory 

 of Natural Selection. 



1. Mimicry as interpreted by H. W. Bates is an advan- 

 tageous deceptive resemblance borne by palatable or harmless 

 species (the mimics) to others that arc unpalatable or otherwise 

 specially defended (the models). Such resemblance will be 

 spoken of as Batesian Mimicry, the examples as Batesian mimics, 

 the interpretation as the Batesian Hypothesis. 



2. The resemblances between specially defended species 

 themselves, although well known to Bates, were not explained by 

 his hypothesis as he conceived it. He suggested that they were 

 an expression of the common results produced by forces common 

 to the environment of the species in cjuestion. Such likenesses^ 

 were subsequently interpreted by Fritz Miiller as the advantage- 

 ous adoption of a common advertisement by specially defended 

 species, whereby the loss of life incurred during the education of 

 young inexperienced enemies was contributed between the similar 

 forms, instead of by each species independently as would have 

 been the case if they had been dissimilar, and possessed patterns 

 requiring each a separate education. Such resemblance will be 

 spoken of as ]\Iullerian Mimicry, the examples as Miillerian 

 mimics, the interpretation as the Miillerian Hypothesis. 



Special Advaxt.\ges of the North American Butterfly 

 Fauna for the Study of Mimicry. 



The butterfly fauna of North America affords probably the 

 best field in which to begin the study of Mimicry, — a subject 

 ^vhich has been shown to possess the most profound significance 

 in relation to the deepest problems by which the naturalist is 

 confronted. The examples are sharp and striking, but not too 

 numerous, and the inquiry can be approached without the con- 

 fusion and excessive strain on the memory which must inevitably 

 at first beset the student of Mimicr^^ in the tropics. But outside 

 the tropics it is also the best field for this study, as will be shown 

 below. 



' It is probable that these Avere the examples which Fritz Miiller had pre- 

 viously sought to explain by the theory of Sexual Selection. 



