276 



THE A3IERICAN NATURALIST 



[Vol. LI 



their influence may be supplemented by that of other 

 enemies is of the greatest interest. 



In this connection Swynnerton's^^ observation that of 

 twenty small bird excreta collected in the African forest no 

 less than eighteen contained scales and small wing frag- 

 ments of Lepidoptera has suggestive value. But, for the 

 moment at least, it is more important that it appears that 

 mimicry might be initiated and advanced by indiscrim- 

 inate feeders, including lizards and insectivorous insects, 

 provided only that they possess color vision. For to 

 whatever extent such influence prevails it obviates the 

 necessity of appeal to the effects of discriminate feeding 

 by birds or other animals, and makes it possible to fore- 

 stall the criticism to which reference has been made above. 



Therefore it is suggested as a tentative explanation of 

 mimicry, that it has commonly arisen as a result of bio- 

 nomic pressure applied first by discriminate or indis- 

 criminate feeders, which by elimination of unadapted 

 variants have forced their accustomed prey to assume 

 color combinations which most effectually conceal it in 

 its normal environment. In addition, for no demoi^strated 

 reason, in a few of the many tlioii^nnds of cases in which 

 colors adapted to tlie cin i roniiicnt and habits of their 

 possessor have been evolved, patterns have appeared 

 which have been sufficiently like one another to deceive 

 enemies which exercise discrimination in their choice of 

 food. Beyond this point the evolution of resemblance 

 may have proceeded according to accepted formulae, but 

 without conspicuousness being involved at any point in 

 the process. 



It is submitted that in our present state of ignorance 

 this construction may be placed upon observed facts 

 rationally and without exposure to the criticism that has 

 been directed against other attempted interpretations. 

 However, the chief classes of facts to be explained and 

 tlio most scrions ()1)jections registered against the Neo- 

 Darwiiiiaii li\ ] ...t iicses of mimicry will be presented, that 



