PLATE 18. 





FRE SH WATER PEARLS, Tennessee. 



2 Dicun ptprs. 



GRAYand BLACK PEARLS, Lower California. 



Natural size . 



^BP 





BLACK PEARLS, Lower California. 

 2 Difim eters. 



CLAM PEARLS, Long Island Sound 



2 Did meters . 



A II lEc l.ithur.mishc. Baltimore 



