PROTECTIVE MIMICRY. 211 



suggestion is that the prototype did exist — i.e., that it has now 

 become extinct ; the mimicking form has established its 

 position by the help of its vanished model, and by its great 

 numbers is able to carry on the deceit, just as a dishonourable 

 firm may trade for a time under an old-established name no 

 longer represented in the firm. This again is a suggestion 

 which is easier to make than either to prove or refute. 



The third explanation is the most satisfactory : Mr. Scudder 

 believes that in such cases we have a general mimicry in course 

 of formation into a special mimicry, — that is to say, the 

 mimicking insect has got so far as to bear a certain likeness to 

 the members of another family or genus, but as yet has not 

 acquired a jiarticular resemblance to any one species of that 

 genus or family. The general resemblance might in the 

 meantime profit the insect. Arge galathea, a butterfly which 

 bears a certain likeness to the Whites, may be such a case ; 

 it is not particularly like any one species of White ; but a 

 comparatively slight change in the relative amount of the 

 black and white in its wings would certainly cause a close 

 resemblance to any of the Whites. The " Gate-Keeper " or 

 '' Wall Butterfly " is possibly another example: it has the rapid, 

 strong flight of a Vanessa, and is not altogether unlike the 

 '• Small Tortoiseshell." 



In the earlier periods of the earth's history reptiles were 

 no doubt the principal enemies with which butterflies had to 

 deal ; considering the obtuseness of modern lizards (see " Ex- 

 periments on Warning Colours," p. 153) to the most glaringly 

 obvious warning colours, and the possibility that the ancient 

 lizards were, if anything, still less discriminating, it is probable 

 that the butterflies of that time trusted more to protective 

 resemblance than to any other way of escaping their foes. 

 With the advent of birds, keen-sighted and apparently more 



