120 



STRUCTURE OP CONCHIFERA OR BIVALVES. 



terminating near one of the canals or siphons, which also 

 carries out the water that has been taken in through the other 

 for the purposes of respiration. The figure also shows the 

 large fleshy foot, by which this animal can move itself along 



Foot - 



Intestine T. 



Stomach - 



Gills. 



Mantle 



Anas 



Respiratory Tubes. 

 Fig. 62. ANATOMY OF MACTRA. 



the ground, or bore into sand or mud. The heart and circu- 

 lating system are less complete than in the Gasteropoda ; but 

 are far higher in character (as are most of the other parts 



