Heart-Cockle and Fresh-zvater Cockle 



113 



stains of dull green. The animal is usually greyish 

 with a tinge of red. It is a northern species, not 

 occurrinof south of Pembrokeshire and Yorkshire. 

 This is the species which produces the British pearls, 

 at one time a somewhat important article of jeweller3\ 

 The so - called " fishery " appears to have been 

 abandoned, probably on the ground that " the game 

 is not worth the candle." We are told tliat in the 



Pearl Mussels, showing pearl within the shell, and 

 detached pearls (1-8) 



middle of the eighteenth century the Perthshire Tay 

 in three years contributed to London pearls valued 

 at £10,000. These varied in hue from white, through 

 pink and green to brown and black, the white pre- 

 dominating, and the pink most in demand. The 

 peasants used to collect the mussels from the 

 mountain streams just before the corn-harvest, and 

 in the oldest and most deformed specimens they were 

 most likely to find the pearls. Yet it is said that not 



