292 IXTKODUCTION TO CONCHOLOGY. 



Mussels, therefore, can opeu and shut their shells at 

 pleasure ; remove to some distance ; fasten themselves to 

 the rocks with threads similar to those of the silkworm ; 

 respire water, like their tinny neighbours; and even doat 

 upon the sui'face of the billows. 



Xow from this we might suppose that the inhabitant was 

 at least provided with feet, in order to walk upon the sand, 

 or that he could swim at ease, in the wide ocean, by means 

 of such appendages as obviate in aquatic natures the neces- 

 sity of wings. But the Creator, who varies means with the 

 obstacles to be surmounted, has provided a peculiar and 

 appropriate mechanism, wliich answers the purpose equally 

 as well. The mollusk is fastened to the upper and lower 

 shells bv two white Hat cords of muscular substance, wliich 

 extend about two inches from the thick part of the body, 

 and gradually decrease in size ; these are capable of being 

 contracted according to his inclination, either for the pur- 

 pose of closing the doors of his impregnable citadel, or of 

 throwing them open. Moreover, every part of this floating 

 pavilion is inlaid with a membrane or epidermis, which, 

 after ha\'ina: been saturated with water, unites so closely as 

 not to admit the escape of a single drop. 



Xot less extraordinary is the creature's position, which is 



