IN LAND UOLLUSCA. 393 



notice by the animals they pursue, or they are no longer 

 liable to pursuit, because the predatory species to which they 

 might perhaps afford a dainty morsel regard them as being — 

 like the creatures they resemble — bad eating or even injurious. 

 In this case the prey deceives the pursuer ; in the former case, 

 on the contrary, the pursuer deceives the prey. The mode of 

 origin of this wonderfully strong protective resemblance can be 

 explained by the well- known principles of selection ; protective 

 resemblances, at first small, have been developed by elimination 

 to a greater, and at last to a perfect pitch of mimicry in form 

 and colour, and also in mode of life. This theory seems 

 extremely plausible, and I believe that in many cases it is the 

 right one ; whether it is in all is another question. Under no 

 circumstances can this theory account for the first appearance 

 of the resemblance, as seems to be tacitly assumed by many 

 writers. But before I entei; on any further discussion of this 

 point, I will describe a few new cases of mimicry observed by 

 myself 



True cases of mimicry among MoUusca have not yet — so 

 far as I know — been observed, although instances of protective 

 resemblance are not rare even among them. This is surprising, 

 since we might suppose that mimicry might originate where 

 a protective resemblance to inanimate objects or plants already 

 existed, for there seems to be an a, priori probability that 

 mimicry may have been developed from this. Perhaps this and 

 other gaps result from our very meagre knowledge of the 

 habits of life of the animals, particularly the invertebrate 

 animals, of other countries. 



Before describing the eases observed by me of mimicry among 

 land mollusca, however, I must make a few remarks on the 

 system of classification of land mollusca now in vogue. The 

 system according to which they are classified is based almost 

 exclusively on the practical requirements of the collector, i.e. on 

 the comparison of the empty shells ; on the other hand, the 

 investigation of the animals themselves has until quite recently 

 been very much neglected. But the anatomical researches carried 

 on during the last ten years — to which I believe I have contri- 

 buted a no inconsiderable share — prove that the shells of such 



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