BIVALVE MOLLVSCA. 



377 



Fig. 170. Groups of Oysters of different ages attached to a block of wood. 



merchandise ; that is to say, it is in a state to be sent to the parks 

 for preservation and feeding. In Fig. 171 we see a group of oysters,* 



* We give this illustration as representing the comparative size of the oysters 

 at different ages ; but it is necessary to state that the specimens were artificially 



