90 



CRUSTACEA. 



ma\ also be observed, that the changes presented to our 

 notice in the Crustacea are quite peculiar, and of a totally 

 different description from those of insects." Mr. Thompson 

 then proceeds to notice the different extraordinary animals 

 known to naturalists under the name of Zoea, which, from 

 their peculiar structure, had greatly perplexed systematic 

 crustaceologists, and states, " It will no longer be a matter 

 of surprise that all the leading naturalists of the present 

 day should have been at a loss how to dispose of /oca in 

 their arrangements of the Crustacea, when it is known that 

 this singular type is not a perfect animal, but merely the 

 larva or imperfect state of the crab ! and not, as has been 

 imagined, an animal sui </eneris" Subsequently, this author 

 states, amongst other circumstances, that he, "succeeding in 

 hatching the ova of the common crab, during the mouth of 

 June, which presented exactly the 

 appearances of Zoea Taurus, with 

 the addition of lateral spines to 

 the corslet; the Crustacea then 

 indisputably undergo a meta- 

 morphosis, a fact which will form 

 an epoch in the history of this 

 generally neglected tribe, and 

 tend to create an interest which 

 may operate favourably in direct- 

 ing more of the attention of 

 naturalists towards them."* And 

 as the Zoese are aquatic animals, 

 furnished with swimming organs, 

 Mr. Thompson concludes, that 

 the circumstance of the young ' " 

 of the Crustacea being thus na- IT 

 tatory, enables us satisfactorily to account for the annual 

 * Zoolojrical Illustrations, p. 9. 



