Royal Physical Society. 403 



Though pearls originate in the mantle, when large they work 

 their way out, and lie loose between it and the shell, or become 

 attached to the " mother-of-pearl" surface of the latter. I have 

 no doubt that pearls can work their way out from this posi- 

 tion, and be found entangled in the meshes of the byssus. I 

 also consider it very possible that an over-distended ovarium 

 is one of the causes of pearls being discharged from the oyster 

 and lost. If this be really the case, it will easily account for 

 the singular fact, that a sample of oysters fished in the month 

 of October will yield a larger proportion of pearls than a batch 

 of oysters fished from the same bank in the months of April 

 and May of the following year. These observations are some- 

 what suggestive, and can be improved upon by future investi- 

 gation. I have now drawn to a conclusion this Report, which, 

 I fear, has extended to a greater length than will suit the pa- 

 tience of the reader. But the subject being one which has 

 been so long neglected, and so little understood, I hope that 

 the Government which has engaged my services, if they do not 

 consider my endeavours as already productive of some practi- 

 cal results, will at least see in these researches glimpses of 

 future success. It is due to Sir Henry Ward here to acknow- 

 ledge my grateful thanks, in which my brother naturalists in 

 all parts of the world will, I am sure, join, for the gracious 

 manner in which my humble services have been retained, for 

 investigating, fundamentally and practically, the natural his- 

 tory of a species of shells which, from the darkest ages of the 

 world to the present time, has been considered of inestimable 

 value in producing one of the richest of gems. Time was 

 when the product of pearl oyster fisheries founded cities in 

 South America and the Red Sea. But what is the state of 

 the islands of the Red Sea, " whose merchants were princes 7 ." 

 They are now thinly inhabited by a miserable race of fisher- 

 men. The sites of some of the oyster-banks in South America 

 are not even now known ; they have been destroyed by being 

 over-fished. New beds are doubtless forming in localities to be 

 yet known to future generations. Ceylon pearl -banks were once 

 on the point of sinking into the same fate, but for the subse- 

 quent observance of more caution. I was present at two of 

 the largest fisheries ever made off Arrippo in 1835 and 1836. 



