Relations of Organized Beings. 363 



ceus to Campephaga phcenicea. Many errors of classification 

 have been caused by mistaking these similarities for true affi- 

 nities. 



Not only are such cases of external resemblance uncon- 

 nected with any agreement in the essential structures of the 

 bodies compared, but there is no conceivable similarity in the 

 functions which they are created to discharge. I think there- 

 fore that it is not going too far, nor departing from that vene- 

 ration which the true naturalist will always feel for Nature's 

 God, to call such superficial coincidences of form accidental. 

 They seem to arise from the exuberant variety of the works 

 of Nature which causes an occasional recurrence of similar 

 forms, without any express design for such coincidences. 

 Nothing can be inferred from such resemblances, either as to 

 essential affinity or functional design ; and they would almost 

 have been beneath our notice, were it not that some authors 

 have regarded them as examples of real analogies. The ad- 

 vocates of the Quinary theory of classification, who regard 

 Analogies to be as important an element in the Natural System 

 as Affinities, often speak of these mere resemblances in the 

 light of true Analogies, and appeal to them in confirmation of 

 their views. Regarding however, as I do, those views to be 

 erroneous, I think it important that the distinction between 

 functional Analogy and mere resemblance should be clearly 

 pointed out; and to render the distinction more marked, I 

 would distinguish the latter by the new term Iconism. 



We must beware indeed of too hastily pronouncing an in- 

 stance of resemblance to be an Iconism, merely because we 

 cannot immediately detect any functional analogy. There 

 may be real reasons for these resemblances, real agreements in 

 the functions to be discharged, which we have not yet de- 

 tected, and perhaps may never discover. A person might 

 say, for instance, that the species of Mantis called the " walk- 

 ing leaf" presents a mere Iconism or accidental resemblance 

 to true leaves ; whereas it is highly probable that this very re- 

 semblance is given to the animal to enable it to remain con- 

 cealed from its foes amid the verdant foliage. Such at least 

 is undoubtedly the intention of numerous instances in which 

 animals present an analogous colour to the surrounding sur- 

 face, and even undergo corresponding changes with it, such 

 as that of the Ptarmigan, which during summer is of a 

 speckled gray plumage, like the lichen-covered rocks which it 

 frequents, while in winter it becomes a pure white when those 

 rocks are covered with snow. 



I have now endeavoured to show that the relations of re- 

 semblance in organized beings are of three kinds, diminishing 



2 C2 



