ANIMAL KINGDOM. 273 



Brogniart. De Blainville indeed, on this account, has 

 called these last animals Ichthyoides. They are distin- 

 guished from all other Vertebrala by undergoing a spe- 

 cies of metamorphosis ; in their young state being Fish, and 

 breathing by branchise ; in their adult state being Reptiles, 

 and breathing by lungs. Sometimes indeed, as in the ge- 

 nera Proteus and Siren, the metamorphosis is abortive ; 

 for even in these singular cases the animal does not ap- 

 pear to have remained in its young state, but by some pe- 

 culiar disposition of Nature adopts a new structure with- 

 out having entirely lost its old one. The Proteus anguinus 

 is a Salamander, which with the usual internal lungs re- 

 tains the external branchiae which properly belonged to 

 its larva state. The genus Siren has a still more imper- 

 fect metamorphosis than the Proteus ; for here the animal 

 without arriving so near to the perfect form of the Sala- 

 mander, which may be considered its type, still takes the 

 lungs and those other peculiarities of internal structure 

 which always mark the adult in the Amphibia. 



Such is the outline of two of the most extraordinary 

 animals in nature, the Proteus anguinus of Laurenti and 

 the Siren lacertina of Linnaeus, the metamorphosis of 

 both which may be termed imperfect or abortive. By this, 

 however, it is not meant that the animal is imperfect, or 

 not fully provided by the Creator with all the organization 

 which it required, in order to retain its place in the scale of 

 nature, but that it has not fully arrived at the structure 

 of the type to which its form ought to be referred, and 

 which in this group is perhaps either the Frog or Sala- 

 mander. In every group there would seem to be a par- 

 ticular form or structure to which all the animals com- 

 posing it should be assimilated. In the more circum- 



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