DESCRIPTION OF A NEW ANODONTA. 



ANODONTA V1RGATA. 



Description. 



Shell subovate, thin and fragile, inflated; umbo prominent, distant 

 from the anterior extremity; beaks pointed, incurved, undulated; um- 

 bonial slope angulated; posterior margin arcuate, extremity angulat- 

 ed; basal margin dilated posteriorly; within bluish and iridescent; 

 cavity very capacious. 



Observations. 



This pretty Anodonta is related to A. undulata, Say, but can be 

 known by the posterior dilatation of the basal margin, which inclines 

 the outline to an ovate form, and by the rays, which are very numerous 

 and unequal, of a beautiful dark green, or the epidermis is green with 

 narrow pale rays, and much resembles Anodonta radiata, nob.; it is 

 comparatively shorter than that species. 



This species was afforded me for description by Dr. Jacob Green, 

 Professor of Chemistry in Jefferson College. Mr. William Mason has 

 specimens from Buck Creek, Clarke county, Ohio. 



Vr v. DESCRIPTION OF A NEW ANADONTA. 



^^ -\TTOtMrW.*] ANADONTA CARINIFERA. 



Shell narrow, elliptical, compressed, thin and fragile; anterior side 

 narrow, rounded at the extremity; posterior side produced, subcunei- 

 form, truncated at the extremity; hinge margin long, straight, elevated 

 or slightly ascending, from anterior to the posterior extremity; beaks 

 not elevated above the dorsal line; basal margin straight in the middle; 

 colour of epidermis olive-green inferiorly, darker above; hinge margin 

 without a callous. Length, 2| inches; height, 1 inch. Inhabits rivers 

 in Kentucky. 



This species is in the fine collection of my friend Mr. John Phillips, 

 who informs me that it is from the Ohio or one of its tributaries below 

 Louisville. It has much the outline of Unio carinifera of Lam. (the 

 common variety of U. complanatus,) but is proportionally more elon- 

 gated, and the posterior extremity resembles that of Unio declivis, 

 except that it is truncated at the tip. 



Unio gibbosus, var. perobliquus, pi. xxvii. fig. 2, 1 have ascertained 

 tQ be a species; it will therefore take the name of Unio perobliquus. 



