CLAMS, MUSSELS, AND OYSTERS. 



41 



A f 



Fig. 42.— Common Clam. — A. showing Siphons partly extended; in., Incurrent Orifice; eat., 

 Excuirent Orifice; /, Foot; m, thickened border of the Mantle projecting" beyond the 

 Edg-e of the Shell; ^, Siphons, greatly extended. (The shell is not dra\vn, as there was 

 no room for it on the page.) The excurrent and incurrent orifices are more open than in A. 



