LAMELLIBRANCHIA. 
35 
entire fish, and in the other a small crab, have been so enclosed 
(see side table-case E). 
The most ancient and, even at the present day, one of the most 
important of the pearl fisheries is that carried on on the western 
shores of Ceylon. ''The Banks," or spots on which the oysters 
grow, are at an average depth of 30 to 60 feet, and extend several 
miles along the coast. The oysters, which should be six or seven 
years old when collected, are gathered in baskets by native divers 
and hauled up by ropes into hundreds of small boats. The shells 
Fi°\ 21). 
Pearl-Oyster (Meleagrina margaritifera). Case 146. 
are then brought to land and placed upon the ground to die and 
putrefy, and then minutely examined for the pearls, which are either 
found loose in the shells or imbedded in the fleshy parts of the 
oysters. As many as two million oysters have been brought ashore 
on one day ; but the number obtained varies very much according 
to the state of the banks. A small proportion of the oysters 
contain pearls ; in some only very small ones (seed or dust-pearls 
as they are called) are found, and very few contain pearls larger 
than a pea, which are so highly valued. In his account of the 
d 2 
