MIMICRY. l8l 



satisfactory. Many cases can be interpreted only by 

 natural selection, those, namely, where from the first, 

 before the imitation had begun, such a resemblance 

 already existed 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 com- 

 menced with forms widely dissimilar 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 Mantidai can look so deceptively like leaves or 

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

 assured 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 excres- 

 cences, 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 advatitageous colouring, 

 within easy reach of many of our readers, is exhibited 

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



