River Pearls ; British and Foreign. 237 



are known locally as Ctagcn las. The Pearl-bearers 

 are confined to the bar of the river, no Pearls being 

 found either in those mussels that are collected 

 higher up or in those found on the sea shore. 

 Each Pearl usually presents in its centre a dark- 

 coloured hard granular nucleus ; and on careful 

 microscopic examination of the mussels from the 

 bar of the Conway, Mr. Garner came to the con- 

 clusion that the Pearls had usually been concreted 

 around a small parasitical Distomiis. 



Fresh-water Pearls have been often found in 

 mussels from the mountain-streams of Cumberland, 

 especially in the Irt and the Esk. In Camden's 

 Britanfiia we read that "At the mouth of the little 

 brook Irt, on the sea coast, are bred a sort of 

 shell-fish or mussel, which gaping there, and sucking 

 in its dewy streams, conceive and bring forth Pearls, 

 or (as the Poets call them) Shell-berries. The in- 

 habitants gather them up at low water, and sell 

 them to the jewellers at London for a trifle, who 



make a considerable gain of them 



Those that are not bright and shining, commonly 

 called Sand-Pearl (and such are those found in 

 these parts usually) are as useful in physick as the 

 finest, tho' not so beautiful. Dr. Lister says he has 

 found sixteen of them in one mussel, and asserts 

 them to be ^^ Senescentitim Musculorum Vitia''^ — 



