oct.— dec. 1857.] The Pearl Oyster of Ceylon. 101 



(g) That a thunder storm will kill some in an aquarium. 

 (Query,) Have thunder storms similar fatal effects on Oysters 

 lying deep in the sea ? 



(h) That the animal can unfix itself from its byssus ; and that 

 crabs, shrimps, and other creatures, force them to form a new 

 byssus, by nibbling through the old one. 



(i) That it can re-form its byssus at pleasure, if in good 

 health and condition. 



(j) That it can live for a long time, without forming a bys- 

 sus; and that it will re-form a byssus when it has recovered 

 strength. 



(Jc) That the power of re-forming its byssus, is not to confine 

 the young animal; but that the largest living Oyster I have seen, 

 can re-form it in an aquarium, as well as in the depths of the sea, 

 but not so actively as the young and middle aged. 



(/) Pearl Oysters are gregarious in their habits. In placing 

 several young Oysters in different parts of an aquarium, they will 

 sooner or later be found attached to each other. The older ones 

 have also this desire ; but their heavy shells impede their motion, 

 and they are contented to remain apart from their fellows. 



(m) That taking the foregoing facts into account, there ap- 

 pears to be no reason why Pearl Oysters should not be translated 

 from their native beds, and made to colonize other parts of the sea. 



(n) That the young, as well as the old, are in spawn from 

 March to September ; and that probably there is no stated period 

 for spawning. 



The whole occupation of the Oyster, when fixed to a spot, 

 appears to be, keeping its valves open, and admitting food to 

 its mouth. For several hours the valves remain open, they then 

 close for a few minutes, or for an hour or two, then open again. 

 At night, the valves remain generally open till towards daylight, 

 when they close, and remain so till the sun shines brightly over the 

 horizon. It is during the early part of the night, or soon after 

 sunset, that they exercise, when required, their locomotive powers. 

 I have watched the Oysters in aquaria for nearly a whole night ; 



