222 ANIMAL COLORATION. 



he named Mimonectes on account of its likeness to a Medusa, 

 The body of this animal is produced into a dome-like structure 

 transparent as glass, from the under side of which depend the 

 minute legs, which give the impression of the tentacles of a 

 Medusa. 



Here we have a case of mimicry which is the more 

 striking inasmuch as it exists between animals widely removed 

 from each other in zoological position. And the poisonous 

 character of the Medusa, armed as it is with innumerable 

 " lasso cells," would seem to make it an excellent model for 

 the defenceless crustacean to copy. It is a pelagic animal- 

 that is, it lives in the surface waters, precisely where Meduste 

 live and there are three or four different species belonging to 

 the genus, all of which have aimed at the same model for 

 imitation. 



But in this instance it is equally doubtful how far the 

 Mimonectes profits by its departure from the usual amphipod 

 appearance: a school of whales or a shoal of pelagic fish, 

 rushing through the water and devouring all before them,, 

 could hardly be supposed to stop and analyse carefully the 

 advantages or disadvantages of selecting or rejecting a given 

 animal as food. And these must be the chief enemies with 

 which small pelagic creatures have to deal. Nor does any 

 theory of aggressive mimicry afford much help. 



Prof. Semper discovered a most remarkable instance which 

 he was at first inclined to regard as confirmatory of the theory 

 of mimicry. This is his description : - 



" During my last stay at Port Mahon, in the Balearic Islands, 

 I found among the polyps of Cladocom cuespitosa a coral 

 which is there very common a species, as it seems to me 

 now, of the genus Myxicola (Annelida). . . . The species of 

 this genus spread out the tentacles with which the head is 



