48 PRACTICAL ZOOLOGY. 



8. Hold the closed shell with the umbones and hinge- 

 ligament uppermost, the latter nearer, and the former 

 pointing away from you. 



The end pointing from you is the anterior end. 



The end pointing toward you is the posterior end. 



The upper edge is the dorsal margin. 



The lower edge is the ventral margin. 



The half shell to your right is the right valve. 



The half shell to your left is the left valve. 



Fix these relations firmly in mind. 



9. Make a drawing of the clam as seen from one side, 

 naming all the parts. 



10. Draw as seen from above, placing this drawing along- 

 side the side view. 



11. Draw the clam as seen from the anterior end. 



12. Observe the color, the degree of cleanness, and 

 general condition of the different parts of the shell, 

 and consider the relations between these facts and the 

 position of the clam when first found. 



DISSECTION OP THE CLAM. 



Put the live clam for a few minutes into water as warm 

 as the hand can well bear. This causes the muscles to 

 relax, so that the shell can be readily opened. If warm 

 water cannot be easily obtained, the clam may be opened 

 with a strong knife, after reading the directions which 

 follow. 



Pry apart the two valves, and insert a small block to 

 keep them from shutting. 



1. Observe a soft white membrane, the mantle, adhering 

 to the inner surface of the shell. Now hold the clam 



