FRESH-WATER MUSSELS. 2OI 



dered below with brown, and above with white 

 cirri, oblong and dark-brown foot, large, tongue- 

 shaped, grayish-yellow or dirty red, gills grayish, 

 labial palps broader than long, and united for two- 

 thirds of their length. The shell is oblong, 2-4 long, 

 and 5 broad. It thus differs from all the others in 

 size. It is found in mountain rivers and streams 

 throughout the British Isles. It is also darker in 

 colour ; the erosion of its umbonal region, and 

 especially in the posterior teeth, being scarcely de- 

 veloped. The lining of mother-of-pearl is equal to 

 half the thickness of the shell ; the shell is dull white 

 under the epidermis. 



The rivers of Scotland produce finely-formed pearls 

 in the mussels of Unio Margaritifera. A pearl which 

 was found in the river Conway, in Wales, was pre- 

 sented by Sir Richard Wynn, of Gwyder, to 

 Catherine of Braganza, Queen of Charles II. This 

 pearl was placed in the king's crown, and it is said 

 that a Scottish pearl, called the Ythan Pearl, is in the 

 Scottish crown. 



The famous Pennant, in 1769, made a tour of 

 Scotland, and in speaking of the river Tay says : 

 " There has been in these parts a very great fishery of 

 pearls got out of the fresh-water mussels from the year 

 1761 to 1764. Ten thousand pounds worth were 

 sent to London, and sold from IDS. to i. i6s. per 

 ounce. I am told that a pearl had been taken there 

 which weighed 33 grains. But this fishery is at 

 present exhausted, from the avarice of the under- 

 takers ; it once extended as far as Loch Tay." 



The Rev. Mr. Bannerman in his account of Car- 



