NATURAL HISTORY. 



•res of Massachusetts Bay. To-day, except in one or two localities in 



E St. Lawrence, there are no natural beds north of Cape Cod. 



1, year the oystermen of these regions bring a cargo of small or 



ed' oysters from the south, and 'plant' them in suitable localities 



along the shore. Here they live, and increase in size, but they fail to 



breed, and so each year the stock has to be replenished from more 



favored localities. 



S >uth of Cape Cod, and especially around the Chesapeake, the oyster 

 breeds freely, and natural beds are abundant, but besides these large num- 

 bers are planted. The requisites for an oyster-bed arc a hard bottom (old 

 oystfer-shells are good), fresh water, and an absence of quantities of sedi- 

 ment, which would soon smother the molluscs. Baltimore is the great 

 centre of the oyster trade, employing thousands of hands. Philadelphia 

 and New York stand next as distributing points. According to the cen- 

 s of 1880 the annual product of the American oyster-fishing amounted 

 1,, over twenty million bushels, the first cost of which amounted to 



si:;. iMio,000. 



Our American oyster is much larger and better flavored than the 

 European species, and we export large numbers to England every year. 

 They have to fight against a considerable prejudice on the part of the 

 English, who feel willing to pay three times as much for their own 

 •natives' as for the American oysters. In Paris 'green' oysters are 

 highly esteemed. In these the flesh is of a decidedly green color, to 

 .plain whi<h, various theories — such as disease, presence of copper — 

 have been advanced. It is now known that it is caused by an element in 

 the food, a diatom very abundant in certain 'oyster-parks' in France, 

 when- at times it forms a thick green scum on the flats when the tide 

 ss out. It does not appear that the color is in any way connected with 

 any appreciable difference in taste, yet in Paris green oysters will bring a 

 much higher price than the natives. 



In the tropics there occurs an oyster which is said to grow on trees. 

 [j really grows on the roots of the mangroves in the swamps, and twice 

 each 'lay. as the tide ebbs, these oysters are left high and dry in the air. 

 The tinkle-shells, or, as they are also called, silver — or gold — shells 

 Aiiomia), arc without economic importance, but are introduced here as 

 an instance of the way in which for years inference will pass for demon- 

 it inn. Anomia was regarded as an intermediate between the brachio- 

 pods and the molluscs, from the fact that, while it possessed the general 

 ructure of the latter, it was fastened to foreign objects, like a brachiopod, 

 by a peduncle which passed through one of its valves. The similarity at 

 first seems striking, but the peduncle is really totally different in the two 



