60 PHOl.AS. 



are still in a young and, probably, a feeble 

 state. May not this process be forwarded by che- 

 mical as well as mechanic means ? May not the 

 peculiar secretion^which, both in the body of the 

 animal, and when separated from it, emits a phos- 

 phorescent light, may not this act in some degree 

 as a menstruum, on calcareous matter, and woody 

 fibre ? If so, the difficulty of procuring an entrance, 

 and of enlarging the internal chamber, would be 

 much diminished. 



It appears, indeed, scarcely possible that these 

 Mollusca should be able to obey the instinct of 

 their nature without some aid from a softening or 

 dissolving fluid. They are doubtless deposited, as 

 soon as formed, in the superficial cavities of the 

 rock or wood; for they are usually discovered in 

 great numbers about the same place, as if from the 

 ovary of a common parent. 



The accessory valves are affixed to the hinge and 

 upper margin by a gelatinous substance, which is 

 liable to decay after the death of the inhabitant : 

 hence arises the circumstance of their being found 

 very frequently defective. 



