PEARLS AND PEARLING 



Fig. 38. Exterior View of the Worthless "Cripple." 



terior of one valve and a corresponding long concave de- 

 pression on. the exterior of the other valve. These pecu- 

 liar distortions are the largest and most distinct at the 

 outside edge of the posterior or thin end of the shell. 

 Both marks lead across the shells toward the umboes, 

 or beaks, gradually becoming smaller and less distinct 

 as they reach the older parts of the valves. The eleva- 

 tion is sometimes called a "deerhorn." These misshaped, 

 or distorted shells are scarce, the valuable "cripples" be- 

 ing much rarer than the worthless ones. 



It is rather difficult to give a description of the two 

 different classes of "cripples," which will be sufficiently 

 plain to show the difference between them. 



For this reason four photographs are supplied, which 

 illustrate the two classes of "cripples/' These are shown 



