THE OYSTER. 



Lesson I. 



Onr oysters, which are the largest ones to be had, will need at 

 least twenty-foar horns in warm water to kill them, even if a hole 

 large enough to admit the water has been nicked in the edge of 

 each one. They are sponged to remove the dirt, withont taking 

 off the brown skin. Boasted and decalcified shells are on hand, too, 

 to show the layers of lime and flesh. Before the lesson, the large 

 mnsole should be cut between the lower valve and the body of the 

 oyster. If we remove the lower valve, the knife will follow the 

 curve of the shell, and will not be so likely to injure the soft parts. 

 The teacher has an oyster with the mnscle still nncut. 



The oyster shell has two valves, one larger and thicker 

 than the other. It is convex on one long edge, and con- 

 cave or nearly straight on the other. It is broad at one 

 end, and the beak is at the opposite narrow end. The 

 deposits of lime are much more uneven than on the clam 

 shell, and the shell is strongly roughened along the lines 

 of growth. One shell has a piece of rock on the thick 

 valve, another has a young oyster fastened to it, and a 

 third has a piece split off from its large valve. These teach 

 us that the oyster was atta ched to some object by the 

 large, thick valve, which is therefore the lower valve. 

 The upper valve is smaller and thinner than the lower 

 one. To find the right and left valves, after holding a 

 clam shell in the proper position, we hold the oyster shell 

 in the same way, with the beak pointing away from us 

 and the concave side uppermost. Then the right valve 

 is on our right side, and the left valve on our left. 



Various Bnbstanees are found on the ontside of the shell.^ Some- 

 thing red proves to be a bit of red sponge. Twisted white tubes 



