THE NAUTILUS. 



VOL. ix. APRIL, 1896. No. 12 



NEW AMERICAN UNIONIDJE. 



BY BERLIN H. WEIGHT, PENN YAM, N. Y. 



TJnio bursa-pastoris sp. nov. PI. Ill, figs, above and below. 



Shell rough, disposed to be both nodulose and pitted, very inequi- 

 lateral, rounded evenly in front, urnbouial ridge nearly obsolete, 

 dorsal margin arcuate, ligament long, thick and much elevated, 

 epidermis reddish-black, rayless, except when very young; sub- 

 stance of shell thick ; cavity of shell shallow and uneven, with a 

 wide flattened area extending from beak cavities to the posterior 

 angle ; cavity of the beaks very deep, compressed and very wide ; 

 pallial impression very rough and deep ; greatest diameter of shell 

 over the anterior edge of the cardinals ; cardinal teeth low, thick 

 and rather smooth ; lateral teeth short, thick and widely separated 

 from the cardinals ; dorsal plate long, wide and usually notched 

 near the cardinals. Terminal cicatrices distinct ; dorsal cicatrices 

 numerous, shallow and under the posterior cardinal. Nacre white 

 and usually much blotched with smoky spots; occasionally with a 

 shade of pink in the center of the cavity. 



Size, length 2-5 inches, width o'6, diameter .1-25. 



Hab. Powell River, Virginia. 



My Cabinet, National Museum ami Mus. Acad. Nat. Sci., Phila. 



Remarks. This species belongs to the group of which U. argen- 

 teus Lea is typical. It differs from that species in having a darker 



