82 University of Michigan 



PLATE XI 



Lampsilis and Actinonaias. Hinge armature. 



Figure 53. Lampsilis ruthveni. Left valve of figure 53, plate XIIL 

 Figure 48. Actinonaias walkeri. Right valve of figure 48, plate X. 

 Figure 49. Actinonaias ivalkeri. Left valve of figure 49, plates IX 

 and X. 



