32 THE BUTTERFLY VIVARIUM. 



culous and obstinate error of classing frogs and 

 lizards, which are regularly vertebrated, along with 

 invertebrated insects, in consequence of the meta- 

 morphosis which these animals undergo, subsequent 

 to the egg stage, in the curious change from the 

 tadpole to the eventual form. But, notwithstanding 

 the frog difficulty, the positive metamorphosis may 

 be considered one of the chief characters of insects ; 

 especially one which distinguishes them from the 

 other classes of invertebrate animals. 



Take the Crustacea, for instance ; they have no 

 metamorphosis — in the true sense of the term, as it 

 is applied to insects — but are endowed, on the other 

 hand, with a far more extended term of existence, 

 giving birth to several successive broods, while 

 insects never become parents but once. 



The Arachnida, or Spider class of invertebrate 

 creatures, though having the insertion strongly 

 marked, differ from true insects in having no antenna?, 

 which in Crustacea are often remarkable ; and, in 

 common with these last, they do not perish like 

 insects after their first brood of young, but live to 

 give birth to several, which undergo no material 

 change or metamorphosis after they are hatched. 



The Myriapods are also distinct from true 

 insects, inasmuch as they undergo no perfect trans- 



