4 o 



MULTIVALVES AND BIVALVES. 



the study of the shell, for malacology, the study of the mollusc. 

 The animal of Tapes decussatus has long been a favourite article 

 of food on the continent. It is oval and white, and the margins 

 of its mantle have a scalloped fringe. The siphons are equal, and 

 separate all the way up, and they are of a yellowish tint, dotted 

 towards the base and middle and speckled towards the end with 

 light brown. The orifice of the inhalent siphon has a double border 

 of a dozen long cirrhi alternated with a dozen that are not so long, 

 but the exhalent siphon has some twenty simple cirrhi, which, like 

 the others, are brown. The foot has a byssal groove, and is large, 

 white, and lanceolate, and, like the other parts, well-marked ; in 

 fact, the species is an excellent one for dissection. Let us, however, 

 as our example, take a better known edible bivalve, the common 

 oyster, which everyone can get and experiment upon. 



Beak 



Culler 



M&nfle 



PARTS OF AN OYSTER (Ostrea edulis). 



Here we have an oyster with the flat or left valve removed. At 

 the top is the beak, and near it is the ligament which opens the 

 valves, and almost in the centre is the adductor which closes the 

 valves, and which being cut through close to the shell by the expert 

 opener, allowed of the left valve being pulled up by the ligament, as 

 if the animal were dead and the muscular power had been lost. 



