252 PROFESSOK OWEN. 



hearthstone. ' I had/ he says, 'not patience to carry 

 the experiment any further, but as far as it went, it 

 left no doubt on my mind that, with the foot alone, 

 and without any silicious particles, without a chemical 

 solvent, and without using the rasping power of its 

 shell, our little animal could easily execute his self- 

 pronounced sentence of solitary confinement for life/ 



Such an inconclusive statement as this would, I 

 feel certain, never have been penned, had its author 

 been so fortunate as to have had opportunity of 

 watching a Pholas at work. 



But, as Professor Owen truly observes, ' Direct ob- 

 servation of the boring bivalves in the act of perfora- 

 tion has been rarely enjoyed, and the instruments 

 have consequently been guessed at, or judged of from 

 the structure of the animal/ Such, evidently, is the 

 case with Mr. Sowerby, and several other writers who 

 treat on this subject. 



Here we may call attention to the folly of natu- 

 ralists endeavouring to tag a pet theory upon all the 

 boring acephala, to the exclusion of every other. 

 Such a system is defended upon the principle that, 

 ' it is much more philosophical to allow that animals, 

 so nearly allied as these in question, are more likely 

 to effect a similar purpose by the same means, than 

 that several should be adopted. Surely this is more 

 consistent with the unity of the laws of nature, and 

 that beautiful simplicity which is everywhere pre- 

 valent in her works/ 



