METAMORf HOSES. 389 



All those creatures which we have been hitherto con- 

 sidering are too imperfect in the construction of their 

 simple organizations to maintain a terrestrial existence ; 

 they are, therefore, confined to a watery medium. In 

 the articulata, we have evidences of higher attributes, 

 and indications of instincts developed in proportion to 

 the increased perfection of organization. Commencing 

 with the annelidans, all of which, except the earth- 

 worms, are inhabitants of the waters, we proceed to the 

 myriapoda, presenting a system intermediate in every 

 respect between that of worms and insects ; we then 

 find embraced in the same order, the class insecta, 

 which includes flies and beetles of all kinds ; and, 

 as the fourth division of articulated beings, the arach- 

 nidans or spiders ; and, lastly, the marine tribe of crus- 

 taceans. 



The most remarkable phenomena connected with 

 these animals are the metamorphoses which they 

 undergo. The female butterfly, for instance, lays eggs, 

 which, when hatched, produce caterpillars : these live 

 in this state for some time, feeding upon vegetables, 

 and, after casting their skins as they increase in size, 

 at last assume an entirely different state, and, dormant 

 in their oblong case, they appear like dead matter. 

 This chrysalis, or pupa, is generally preserved from 

 injury by being embedded in the earth, from which, 

 after a season, a beautifully perfect insect escapes, and, 

 floating on the breeze of summer, enjoys its sunshine, 

 and revels amidst its flowers. 



No less remarkable is the metamorphosis of the ca- 

 ducibranchiate amphibia, passing through the true fish 

 condition of the tadpole to the perfect air-breathing 

 and four-footed animal, the frog. 



A metamorphosis of the crustaceans, somewhat similar 

 to that which takes place in insects, has been of late 

 years creating much discussion amongst naturalists : 

 but the question appears to be now settled by the 



