MYTILID^. — MUSSEL. 67 



breadth; but in 1862 I produced two specimens from 

 Exmouth, which had been dredged, the largest measur- 

 ing five inches in length and two and a half in breadth, 

 the other four inches long and one and a quarter 

 wide. Large mussels are brought from Padstow, and 

 are sold in the Truro market ready boiled for eating, 

 and, when cooked, the fish measures quite two iuches 

 in length ; the colour is like the yolk of a hard-boiled 

 egg and the flesh is very sweet and tender. The shells 

 of these, measured four inches in length, and two and 

 a half inches in breadth. Though mussels are a valuable 

 article of food, and considered wholesome, yet many 

 cases of poisoning by mussels have occurred ; but it 

 may generally be traced to their having been gathered 

 from either the sides of docks, or piers, where there 

 are copper bolts or nails, or from ships that are copper- 

 bottomed ; or else from the neighbourhood of large 

 town sewers, the sewerage water running over the 

 rocks on which the mussels grow. In the ( Field/ 

 November 15th, 1862, is an interesting account of an 

 experiment made on oysters that had become so im- 

 pregnated with copper as to be as green as verdigris. 

 They were taken from Falmouth harbour. An at- 

 tempt was made to extract the copper from them ; 

 and, after putting a hundred or more into a large 

 crucible, reducing them to ashes, and continuing to 

 increase the heat until the copper was melted; the 

 produce was a bright bead of pure copper, which, ac- 

 cording to the description, would be about the size of a 

 large pin's head. Mr. Penwarne, who communicated 

 this article to the ' Field/ adds, that the oysters may 

 have lain on a lode, or the copper might have accu- 

 mulated from the wash of the stamping-mills. This 



f 2 



