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 ( Uroaalpinx cinerea): 

 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., 



