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, through 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 //.uag, from fjjhoo, to compress^ 
(whence the word Mya is derived,) v/as formerly 
applied to the Genus Mytilus. 
