PHOLAS. 



evidently designed to protect the shell from external injury 

 whilst its inhabitant is thus employed. At the same time a 

 beautiful variety of tints evince that minute attention to 

 the finishing and decorating of all created things which 

 everywhere prevails. But why this feeble creature is in- 

 structed to form an excavation in sand or lime-stone, whilst 

 others are permitted to range at liberty, we cannot under- 

 stand; or how this object is effected by means of a peculiar 

 secretion, has hitherto eluded our researches. 



There is another quality in this tribe of mollusks, which 

 demands a brief description. It is that of emitting a phos- 

 phorescent liquor, which illuminates whatever it touches. 

 This peculiarity, observed by Pliny and other ancient natu- 

 ralists, has furnished a subject for various observations 

 and experiments to different learned men, especially to 

 M. Eeaumur and M. Beccarius, who particularly devoted 

 their attention to the subject of phosphoric light. 



The luminous quality of the Pholas is in proportion 

 to its freshness ; but even when in a dry state, it may be 

 revived by the application of fresh or salt water. Brandy 

 immediately extinguishes the liglit. A solution of sea- 

 water increases it; sal ammoniac diminishes it a little; 

 oil of tartar nearly extinguishes it, and the acids entirely. 



2b 



