PEOTECTIVE EESEMBLANCES IN VERTEBKATA 71 



eiders that they were undoubtedly of the same species. 

 When placed in an aquarium the molluscs always 

 sought their own corals, but if red molluscs and 

 yellow corals were put together the former took no 

 notice of the latter. 



It is very interesting to find that Mr. Garstang 

 notices a similar association between species allied, to 

 the above at Plymouth. A reddish coral {Gorgonia 

 verrucosa) is attended by a gastropod {Ovula patida)^ 

 adapted in form and colour for concealment on the 

 stems of the Gorgonia. 



It might be argued that these are cases of Pro- 

 tective Mimicry, inasmuch as one animal resembles 

 a portion of another for the purpose of protection. 

 Similar examples are to be found in certain parasites 

 which resemble the colour of the hair or skin of 

 the animal they infest. Protective Mimicry, how- 

 ever, leads one animal to be mistaken for another, 

 and thus to live upon the reputation of the latter. 

 Protective Kesemblance simply renders an animal 

 difficult to detect. Animals defended in the former 

 manner are almost invariably conspicuous ; in the 

 latter they are admirably concealed. Mr. Garstang 

 tells me that Gorgonia is exempt from the attacks of 

 fishes, so that the molluscs gain additional advantage 

 by resembhng an inedible form. Inasmuch as con- 

 cealment appears to be the chief object of the form and 

 colour, the example falls under Protective Kesemblance, 

 although it leads in the direction of true Mimicry. 



