134 ORGANIC EVOLUTION 



secretion of its scent glands, advertises its disagreeable char- 

 acter by its conspicuous black-and-white color (Plate 72, B}. 

 There are a number of similar instances among the Mam- 

 malia. The black-and-white color of the skunk probably 

 renders it inconspicuous when hunting its prey on moonlight 

 nisfhts, the black resembling shadows, and the white marks 



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blotches of light. Its color, therefore, is probably both 

 aggressive and warning coloration, aggressive by night, 

 warning by clay. 



Similar phenomena of warning coloration are found 

 among the different groups of marine invertebrates, but, 

 as the forms are less familiar, we will not refer to them. 



Convergence in warning coloration. 



One very interesting feature is observed in the warning 



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coloration of the inedible butterflies. Different inedible 

 species, belonging to distinct genera or even to distinct 

 families, in many instances show the closest similaritv in 



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color and in color pattern, and often also in shape 

 (Plate 77, AD). This was for a long time a puzzle to 

 students of color phenomena, until Bates, an English 

 naturalist, suggested that this convergence in coloration 

 among unrelated inedible butterflies must decrease consider- 

 ably the number of experiments necessary to teach young- 

 birds and lizards the evil character of the butterflies, since 

 they are all of one pattern, and so save from destruction 

 many individuals which would be sacrificed did their enemies 

 need to learn a separate pattern for each inedible species. 

 This suggestion seems plausible. It is, at least, the best we 

 have yet found. 



