82 SATl'RAL HISTORY. 



On the Coast, per contra, the danger of oyster-eating almos* 

 always arises from gross carelessness on the part of some one or 

 other. Nobody gets poisoned with oysters at the Clubs, or at the 

 Apollo Bunder, where proper care is taken in the matter. In one 

 case that came under my notice, I myself, and my household, 

 ate safely of a basket of oysters for three days, at almost every 

 meal ; and a man who had eaten them there was afterwards 

 "poisoned" with oysters oat of that very same basketfal, only m 

 the meanwhile they had passed out of my hands. 



As for " copper in oysters/ 7 supposed to be derived from rocks, 

 it is a fact that the juices of oysters do, at least occasionally, con- 

 tain a trace of copper, but a dose of copper likely to affect a man 

 would probably be enough to kill a whole keg fall of oysters, certainly 

 far more than enough for any number of 03's-ters that the mam 

 could hold. If any gentleman doubts this, let him mix a dose of 

 verdigris with the water of an aquarium, and see how long any oyster 

 or any thing else, lives in the poisoned water. 



The fact is that nothing is so hateful to shell-fish, and especially 

 to the Conchifera, as the exide of copper ; and that is the reason why 

 it is useful on a ship's bottom. Sir Humphry Davy prevented the 

 copper on a ship's bottom from rusting (by a galvanic experiment 

 which need not be described here), and the result was that that ship's 

 bottom immediately became foul ; the Conchifera and Barnacles 

 having no further reason to fear it. 



We have several other oysters here; one has the lower valve plaited, 

 making it look something like a bird's foot. This is little eaten. 

 Another small and rare species, of the creeks has the valves long, 

 narrow, and rounded like dinner-knife blades, seldom exceeding ]-| 

 inch in length. I have not got here the "Mangrove oyster" 

 (Den drostrea) which " grows on trees." All oysters, or nearly all, 

 will grow upon dead wood. The connection of "oyster poisoning" 

 with Mangroves is a mare's nest. 



Of the so-called Pearl-oysters, Placuna Placenta, the Window- 

 oyster, is common here ; and is still sought after as containing seed- 

 pearls. It seldom produces large pearls; and since it ceased to be 

 used as a substitute for window-glass, its value has fallen off. I 

 once got here a single small fresh valve of the true Pearl-oyster 

 (Avicula margaritifera). It must be very rare. 



Our Scallops are small and unimportaut ; and we have, I think, 

 only one small Spondyle, conspicuous by its orange colour ; bnt 



