CHAPTER IV 



THE METAMORPHOSES OF CRUSTACEA 



THE great majority of Crustacea are hatched 

 from the egg in a form very different from that 

 which they finally assume, and reach the adult state 

 only after passing through a series of transformations 

 quite as remarkable as those which a caterpillar 

 undergoes in becoming a butterfly, or a tadpole in 

 becoming a frog. Many of these young stages were 

 known for a long time before their larval nature 

 was suspected, and it is one of the curiosities of the 

 history of zoology that, even after the actual changes 

 from one form to another had been observed and 

 described in several Crustacea, many eminent 

 naturalists refused to believe in the possibility of 

 their occurrence. This scepticism was largely due 

 to the fact that the common fresh- water Crayfish, 

 when hatched from the egg, has practically the same 

 structure as the adult, and it was assumed that other 

 Crustacea were developed in a similar fashion. 

 Although certain cases of metamorphosis had been 

 actually seen and described by naturalists in the 

 eighteenth century, these observations were for- 



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