392 THE LIFE OF A BIRD. 



days could scarcely have made the mistake alluded 

 to. Yet, under the most strange and extravagant 

 superstition, birds were in former times supposed 

 to have been produced by trees ; and the case 

 of the barnacle goose is an instance of this 

 absurd and ignorant fancy. In some old engrav- 

 ings the bird is represented as the offspring of a 

 tree, bearing the shells of a molluscous animal. 

 Thus not only were the extremely opposite natural 

 classes, shell-fish and birds, confounded together, 

 but the animal and vegetable kingdoms were so too. 

 Such an error is doubtless unlikely to occur in 

 our enlightened age. Yet the student of nature 

 ought to be well able to assign a reason for the 

 improbability of the story, and to show that each 

 of these forms of organic life the tree, the bird, 

 and the mollusk has certain distinctive charac- 

 ters, which separate them to the widest possible 

 extent from each other. Let us, therefore, pay 

 that attention to these points in the history of a 

 bird, which will put us in possession of such facts 

 connected with its characteristic features as to 

 enable us to state with precision what structural 

 peculiarities constitute a bird, and wherein it 

 differs from every other class in the animal king- 

 dom. 



