MIMICRY 



69 



Fig. 28. — A, Stromhvs onauritianus 

 Lam., which mimics Conus in 

 shape. B, Conus Janus Hwass, 

 Mauritius. 



Actinian mimics the nudibranch than vice versd, since Aeolis is 

 known to be unpalatable to fishes. 



Certain species of Strombus (mauritianus L., hiliuanvs L.) 

 show a remarkal:)le similarity in the 

 shape of the shell to that of Conus, 

 so much so, that a tiro would be 

 sure to mistake them, at first sight, 

 for Cones. In the case of S. lull- 

 nanus at least, this similarity is 

 increased by the possession of a 

 remarkably stout brown epidermis. 

 Now Conus is a flesh-eating genus, 

 armed with very powerful teeth 

 which are capable of inflicting even 

 on man a poisonous and sometimes 

 fatal wound (seep. QQ\ Stromhus, 

 on the other hand, is probably frugi- 

 vorous, and is fm*nished with weak and inoffensive teeth. It is 

 possible that this resemblance is a case of ' mimicry.' It is quite 

 conceivable that powerful fishes which would swallow a Stromhus 

 whole and not suffer for it, might ac(|uire a distaste for a Cone, 

 which was capable of lacerating their insides after being swal- 

 lowed. And therefore the more like a Cone the Stronibus became, 

 the better chance it would have of being passed over as an 

 ineligible article of food. 



Protective coloration is not uncommon among the Mollusca. 

 Littorina ohiusata is habitually found, on our own coasts, on 

 Facus vesiculosus, the air-ljladders of which it closely resembles 

 in colour and shape. Littorina fcujoclus, a large and showy 

 species, resembles so closely the spongy crumbling rocks of 

 Timor, on which it lives, that it can hardly lie discerned a pace 

 off. Helcion pellucidum, the common British ' blue limpet,' lives, 

 when young, almost exclusively on the iridescent leaves of 

 the great Laminariae, with the hues of which its own con- 

 spicuous blue lines harmonise exactly. In mature life, when 

 the Helcion invariably transfers its place of abode to the lower 

 parts of the stalk and finally to the root of the Laminaria, which 

 are quite destitute of iridescence, these blvie lines disappear or 

 become much less marked. 



The specimens of I'urjmra la^nllus wliich occur at Xewquay 



