ISO 



THE AMEBIC AN NATURALIST [Vol. L 



Thus, referring by way of illustration to the somewhat analogous 

 case of the coat colors of rodents, he says : 



In certain features the rabbit might be said to " mimic " the mouse, 

 in other features the guinea-pig. 



It is a significant fact in this connection that the various models 

 "mimicked" by the different species of a polymorphic species 

 are almost always closely related, and hence may be expected 

 to exhibit color patterns based on different combinations of iden- 

 tical factors. 



In criticism of Wallace 's laws of mimicry, Punnett points out 

 the fact that although the mimic and model usually occur in the 

 same locality this is not always the case, the cooperation of mi- 

 gratory birds being invoked to explain the exceptions. 



Kegarding the defenselessness of mimics as compared with 

 models, it is noted that the "mimic" is often a swifter flyer, and 

 hence better prepared for defense than the model. 



Exceptions are given to the rule that the models are more 

 numerous than the mimics, and that the mimics differ from the 

 most of their nearest allies. The Pierid genus Dismorphia, for 

 example, includes prominent South American mimics which 

 differ strikingly from the "whites" of the Temperate Zone but, 

 unfortunately for the theory of mimicry, only about a dozen 

 of the seventy-five described species are white, the rest present- 

 ing a "wonderful diversity of color and pattern. ' ' Among them 

 are species clearly non-mimetic as regards color, which by simple 

 substitution of one color for another in the spots would be trans- 

 formed into a 1 1 mimetic ' ' species. 5 



The author concludes that 



It is on the whole unusual to find cases where a single species departs 

 widely from the pattern scheme of the other members of the genus and 

 at the same time resembles an unrelated species. 

 Two of the best examples are our American ' ' viceroy ' ' and the 

 pierid Pareronia. ' ' Mimicry tends, ' ' he adds, 1 ' to run in certain 

 groups" and "in many cases at any rate little meaning can be 

 attached to the statement that the imitators differ from the bulk 

 of their allies." 



o The reviewer recently observed in Porto Eico a case bearing upon this 

 point, in Leptalis (Dismorphia) spio, which closely resembles in color ana 

 general shape the very common Helwonius charitonius. A color variety ol 

 the former, however, is found in certain localities on the island, in which 

 orange replaces yellow in the color pattern, rendering the resemblance to the 

 Heliconian less apparent. A simple mutation of orange into yellow would 

 make this an excellent example of "mimicry." 



