78 



BRANCH MOLLUSCA 



dreds of vessels are engaged in this industry. Pearls of various shapes are 

 found. Their colors may be white, yellow, pink, blue, red, green, or even 



Fig. 57. Some enemies of the oyster: 1, Drill (Urosalpinx dnerea); 

 2, mussel (My'tilus edulis) ; 3, Sabellaria vulgaris; 4, periwinkle (Fulgur 

 carica). (Report of Fish Commision for 1897.) 



black. Round lustrous white ones are most prized in Europe and America, 

 but those of the yellowish hue are preferred by Asiatics 



