MOLLUSCS. 87 



pea in size, but more or less imperfect ones, much larger, are common. 

 The largest pearl known was two inches in length and four in circumfer- 

 ence, and weighed three ounces and three-quarters. While the precious 

 stones can have their value enhanced by judicious cutting, there is no such 

 chance with a pearl. In a gem the beauty lies in the polish of the facets, 

 but a pearl is not polished, and no art can make a surface like that of 

 nature. White pearls are most common and most prized, but other colored 

 pearls — red, purple, and black — are not uncommon. Recently black 

 pearls have advanced in favor, and to-day command ten times their former 

 price. 



Many other molluscs besides the pearl-oyster produce pearls, but only 

 those which have a pearly lining to the shell can afford pearls of value. 

 It is not rare to run across pearls in the common oyster or clam, but these 

 are always of a dirty white, and are absolutely without beauty or value. 

 Many of the fresh-water mussels, on the other hand, have pearly shells, 

 and these afford pearls, some of which are worthy of position alongside of 

 those produced by the true pearl-oyster. As long ago as the Roman occu- 

 pation of Britain, pearls were collected from the fresh-water mussels, and 

 the same is true to-dav ; for in Scotland and Bohemia, as well as in other 

 parts of Europe, the fresh-water pearl fishery is an industry of considera- 

 ble importance. 



In 1857 a pearl was found in a fresh-water mussel in New Jersey, 

 which was sold by Tiffany & Co. for twenty-five hundred dollars. It is 

 now in the possession of the ex-empress Eugenie, and is valued at ten or 

 twelve thousand dollars. This find created great excitement, and all over 

 the United States people went to examining the mussels in the streams 

 and ponds, in the mad search for pearls. Some rivers were completely 

 cleansed of molluscs, and the result was the finding in all of pearls to the 

 value of about ten thousand dollars. Since that time the search has greatly 

 fallen off, but each year some are found, Texas to-day furnishing the most. 

 In looking for pearls in fresh-water mussels, one should neglect all the 

 young and the perfect individuals, and examine only the old, sickly, and 

 distorted specimens. The Indians knew that the fresh- water mussels pro- 

 duced pearls, and they also apparently prized them, for numbers of them 

 are found in their graves and mounds. The largest find of this character 

 was that by Professor Putnam, who exhumed over sixty thousand of them 

 from a single mound in the Little Miami Valley, all of them so altered 

 and decayed by their long sojourn underground as to be of no value, 

 except as archaeological specimens. 



A curious belief regarding the origin of pearls is that given by Tonti, 

 in 1698. He accompanied La Salle in his voyage down the Mississippi, 



