FRESH-WATER MUSSEL* 



ANODON. 



A. General Characters. 



I. Bivalve shell enclosing the animal, the valves 



fastened together by a hinge along one the 



dorsal side. 



1. Straight dorsal side. 



2. Curved ventral side. 



3. Anterior end wide and rounded. 



4. Posterior end narrower and more pointed. 



5. The bivalve shell bilaterally symmetrical. 



6. Concentric lines, lines of growth of the shell. 

 Diagram ! 



Force apart the valves of the shell about half an 

 inch and insert a loedge. Find : 



7. The mantle, lining each valve of the shell. 

 With the handle of a scalpel separate the mantle 



from the right valve. Find : 



8. The adductor muscles. 



With a strong scalpel cut through the attachment 

 of the muscles on the right side close to the 



* Living mussels are advertised by some of the dealers in Jabo 

 ratory supplies. For preservation they should be put for twenty- 

 four hours into 70 per cent, alcohol (which is reduced to a much 

 lower per cent, by the water inside the shell), then changed to 70 

 per cent, alcohol for twenty-four hours, and kept permanently in 

 80 per cent, alcohol. 



58 



