MOLLUSCA OR UNIVALVES. 233 



outer lip; the latter is sometimes reflected 

 inwards towards the middle part. 



The animals of the Strombus occasionally 

 produce pearls. Mr. Wood, in his "Zoography," 

 relates that he saw a pink pearl which was taken 

 from the body of the animal of the Strombus 

 gigas, which is caught for the table off the island 

 of Barbadoes. The pearl was discovered by 

 chance, whilst the men were employed in 

 cleaning the fish. Its weight was 24 grains ; 

 but it would have been more valuable if it had 

 been round. The same author states that only 

 four of these pearls had been discovered in the 

 vast numbers of fish that are annually brought 

 to market in that part of the world, though he 

 has reason to believe that this is in some mea- 

 sure owing to the carelessness of the negroes. 

 This pearl was exactly of the same colour as 

 the interior coat of the shell.* 



Family 13. — Purpurida. f 



This family has the shell either notched at 

 the base, or terminated by a short canal turned 



* Penny Cyclopaedia, article Strombidcs. 

 \ Les purpurifereSy Lamarck. 



