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Second Sub-Genus STROPHITUS. 



Hinge with a marginal projection under the 

 apex. 



The Anodonta undulata of SAY forms this 

 sub-genus, which, with the following, might be 

 considered a genus. 



Third Sub-Genus LASTENA. 



Hinge with two transverse wrinkles, obtuse, 

 almost lamelliform, divergent on each side of the 

 apex; ligament straight, membranous, double, 

 either anterior or posterior. 



SPECIES LVIII. Anodonta Ohiensis (Lastena 

 Ohiensis.} 



Shell very thin, fragile, translucent, ventricose, 

 elliptical, somewhat winged, and obliquely trun- 

 cated posteriorly ; apices entire, wrinkled ; epi- 

 dermis smooth, olive coloured or brown ; nacre 

 bluish. Length f diameter and axis of the 

 breadth. 



Var. 1. radiata olivaceous copper colour- 

 ed, with radiated bands, greenish, 



