MIMICRY. l8l 



between the imitating and imitated forms as to render 

 confusion possible; where, therefore, the resemblance so 

 conducive to the preservation of those in which it was 

 the strongest, needed only to be increased by natural 

 selection. Darwin '' is also of opinion " that the process 

 probably has never commenced with forms widely dis- 

 similar in colour." 



A peculiar, simpler and long known mimicry, is when 

 animals have accommodated themselves in colour to 

 their habitats in such a manner as not to attract the 

 attention of their enemies, and likewise to deceive their 

 prey. Who, in the days when he chased butterflies, did 

 not learn how difficult it is to recognize certain evening 

 and nocturnal flyers on the bark of trees, as they quietly 

 sit with their dusky brown or gray-striped or speckled 

 wings, outspread in a roof-like shape? The tree locusts 

 and Mantidae can look so deceptively like leaves or 

 twigs, that it is only by the touch that one can be as- 

 sured of their real nature. Wallace relates that one of 

 the Phasmidae (Ceroxylus laceratus), which he obtained 

 at Borneo, was so covered with pale olive-green ex- 

 crescences, that it looked like a stick covered with moss. 

 The Dyak who brought him the animal declared that, 

 although alive, it was really overgrown with moss, and 

 the naturalist himself was only convinced of the con- 

 trary by the closest examination. 



A remarkable example of advantageous colouring, 

 within easy reach of many of our readers, is exhibited 

 in most species of the flat-fish (Pleuronectidse), now so 

 frequently kept in aquaria. Observe the gray or brown- 

 ish speckled creatures, as with a few strokes of their 

 fins they partially cover their upper surface with sand. 



