UNITED STATES AND ARCTIC AMERICA. 213 



lations at the tips on each valve. It has not the acuminate recurved beaks of 

 Kennicottii, herein described, nor is it so much inflated. It need not be confounded 

 with that species. It is somewhat allied to Oregonensis, (nobis,) but is not so 

 wide in proportion, nor so high in the carina, nor so much inflated below, and has 

 much closer lines of growth. I dedicate this species to my friend, the late Sir 

 George Simpson, Governor-in-Chief of the Hudson's Bay Company. I am per- 

 sonally indebted to him for specimens from Upper Canada and Columbia in former 

 years, and he has at all times, with great liberality, promoted the objects of 

 science, as well as those of geographical discovery in Arctic America in various 

 ways. 



Anodonta virgulata. PI. 33, fig. 282. 



Testa laevi, elliptiea, ventricosa, insequilaterali, postice obtuse angulata ; valvulis subtenuibus ; nati- 

 bus proniinulis, ad apices undulatis ; epidennide vittata, virido-radiatl ; margarita cseruleo-alba 

 et iridescente. 



Shell smooth, elliptical, ventricose, inequilateral, obtusely angular behind ; valves 

 rather thin ; beaks slightly prominent and undulate at the tips ; epidermis banded, 

 with green rays ; nacre bluish white and iridescent. 

 Proe. Acad. Nat. Sci., 1857, p. 86. 



Hah. — Roanoke River, Weldon, North Carolina, Prof. Emmons; and Washington 

 County, Georgia, Rev. G. White. 



My cabinet and cabinets of Prof. Emmons and Rev. G. White. 

 Diam. 1-3, Length 1-7, Breadth 3 inches. 



Shell smooth, elliptical, ventricose, inequilateral, obtusely angular behind and 

 rounded before ; substance of the shell rather thin, slightly thickened before ; 

 beaks slightly prominent and undulate at the tips ; ligament rather long, thick 

 and dark brown; epidermis banded with green rays and very distant marks 

 of growth ; umbonial slope raised and rounded ; posterior slope wide, dark, 

 with three slightly raised lines on each valve ; anterior cicatrices confluent, 

 rather large and indistinctly impressed ; posterior cicatrices confluent, large, scarcely 

 perceptible ; dorsal cicatrices very slightly impressed and placed nearly in the 

 centre of the cavity of the beaks ; cavity of the shell deep and broad ; cavity 

 of the beaks very shallow and very obtusely angular; nacre bluish white and 

 iridescent. 



Remarks. — I have several specimens before me from North Carolina and Georgia. 

 That figured is from the Roanoke River, at Weldon, and is smaller than those from 

 Georgia. It seems to be between fluviatilis and decora, and perhaps nearer to the 

 latter, the plane of the valve forms a very regular ellipse. It is more inflated than 

 fiuviatilis usually is, and in the undulations of the beaks it differs, those of virgulata 

 being more like Ferussaciana, (nobis.) 



