LECTURE VI. 289 



of the mauis. The coarse scales and spines 

 of fishes, the bucklers of the sturgeon, and 

 hard projections of the skin of the croco- 

 dile, all serve the same purposes. The 

 porcupine and hedgehog have quills like 

 those of birds, but they want the fibrous 

 part or plumage, and are remarkably strong 

 and pointed. They may indeed be consi- 

 dered as a defence to the animal, when 

 they lie horizontally; but as it is well known 

 these animals, when attacked, suddenly 

 squat down, bringing their fore and hind 

 legs near together, and putting their head 

 between their fore-legs, then contracting 

 their skin in a direction towards their belly, 

 by an appropriate muscle, the quills are 

 raised, and a chevaux de frise of pointed 

 spears presented in every direction to the 

 assailant. When the horny or crustaceous 

 investments of animals are of one piece and 

 unyielding, there is a necessity, whilst the 

 animal is growing, for casting these cover- 

 ings and forming new ones, adapted to the 

 increased bulk of the animal ; and we find 

 that snakes and lobsters thus cast their 

 skins or shells. 



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