116 



ILLINOIS BIOLOGICAL MONOGRAPHS 



[214 



EXPLANATION OF PLATE 



Fig. 22. Anodonta grandis. 

 Fig. 23. Anodonta grandis. 

 Fig. 24. Anodonta grandis. 

 Fig. 25. Amblemaundulata. 

 Fig. 26. Amblema undulata. 

 Fig. 27. Amblemaundulata. 

 Fig. 28. Amblema undulata. 

 margin of shell. 



Right valve with pearly growths at anterior end. 



Left valve with injured portion folded inward. 



Pearly formation in left valve. 



Right valve uninjured. 



Left valve with large blister inside pallial line. 



Left valve with abnormal pallial line. 



Left valve with pin-head pearls between pallial line and 



Pathologic mussels from Salt Fork. 



