48 MYA. 



and the shell is only to be classed by other points 

 of generic resemblance. It would perhaps be bet- 

 ter if this genus were recast ; for, as it at present 

 stands, it includes, most palpably, several stolen 

 species. The inhabitants of the Mya burrow in 

 the sand or mud, leaving a channel ,Hhrough which 

 they occasionally thrust their retractile proboscis. 



Mya margaritifera, a species which is found 

 chiefly in the large rivers of northern latitudes, is 

 known to produce pearls, partial secretions of the 

 same matter which forms the inner coating of the 

 shell, in considerable abundance. The British 

 islands, especially Ireland, have been considered 

 famous for their fisheries of the Mya, and a few 

 pearls of great value have at different periods been 

 obtained from these sources ; but the quality of 

 British specimens in general is by no means held 

 in the highest estimation. 



The Greek original //<ua£, from pvu, to compress, 

 (whence the word Mya is derived,) was formerly 

 applied to the Genus Mytilus. 



