Mother-of 'Pearl Shell. 99 



the hole of a borer is disclosed, the shell is passed 

 aside, \{, however, the shell is solid at that spot, 

 the blister is cut out with a hammer and punch, 

 and split open, in the hope of finding a Pearl 

 within. 



The MeleagrincB, in common with all oysters 

 and mussels, produce an enormous quantity of ova, 

 a very small proportion of which ever escape their 

 numerous enemies, and succeed in establishing 

 themselves in their sub-marine world. The "spat" 

 is carried here and there by the currents until it 

 succeeds in attaching itself to some obstacle that 

 may have arrested its onward course, and here it 

 probably remains for life, unless some accident 

 happens to detach it again, such as the heavy seas 

 caused by hurricanes. Several thousands of Pearl 

 shells have been washed up on the Australian coast 

 after a " blow." Turtle also may disturb shells ; they 

 are very fond of the luscious morsel within, and full- 

 grown shells may be found bitten to pieces by their 

 powerful mandibles. There was found by our fleet 

 in 1884, a shell that at a certain period of its 

 growth had been broken, probably by a turtle, but 

 the oyster had succeeded in secreting fresh layers 

 of nacre within, before harm came to it, and the 

 old accident was only detected by the fracture at 

 the back of the shell. This case again furnishes 



