"CRIPPLED'' SHELLS THAT YIELD PEARLS 157 



Fig. 39. Exterior View of the Valuable "Cripple," which 

 Yields the Pearl. 



in two sets. One set illustrates the exterior of the shells, 

 while the other set shows the interior of the same shells. 



The shells which are illustrated are taken from the au- 

 thor's collection of "cripples," which he has gathered in 

 his work as a pearl hunter in various localities. The val- 

 uable one was found by him in the Illinois River, about 

 one mile south of Florence, Illinois, and contained a 

 beautiful low-button pearl, which weighed eleven grains. 

 In Fig. 41, the arrow indicates the socket in which the 

 pearl was found. The shells which contain sockets are 

 very rare. Most pearls rest in the folds of the mantle 

 or against the smooth surface of the nacre. 



In the views which show the exterior of the shells, the 

 two parts of each shell are in juxtaposition, while the 



