"CRIPPLED" SHELLS THAT YIELD PEARLS 163 



shells have some imperfections. The faults are mostly 

 caused by pressure of the shells against the pearls. 



While the "crippled" shells produce most of the pearls, 

 it should be remembered that perfect ball pearls of fine 

 luster are occasionally found in shells that are normal. 

 The pearls which are found in perfectly normal shells do 

 not touch either shell and are therefore perfectly round 

 and have a fine luster. Such pearls are often found in a 

 sort of sack hanging inside of the palaal line near the 

 gills. 



Mr. Noah McFadden found one of this kind in the 

 Illinois River, near Meredosia. He sold the pearl for 

 $1,000.00. The pearl was perfectly round with a fine 

 luster and weighed twenty-seven grains. The shells 

 which contained the pearl were perfectly normal. 



While the perfectly normal shells do not often contain 

 pearls, the gems which are found in them are very likely 

 to be perfect. 



There is another kind of "cripple" which produces 

 baroques and slugs. These "cripples" are often the re- 

 sult of some kind of accident, in which the shells have 

 received some injury. Occasionally a mussel becomes in- 

 jured in a manner which moves one valve farther for- 

 ward and the teeth are broken off. Such shells often 

 produce a large number of slugs. 



Other shells become wedged between solid rocks and 

 grow into peculiar shapes, but are not so likely to yield 

 slugs. 



There are many ways in which the mussels may be in- 



