CHIEFLY OF THE UNITED STATES. 43 



to diiplicature. The marks of growth are very numerous, regular and close. This 

 specimen evidently had over twenty. 



Unio crebrivittatus. pi. 15, fig. 41. 



Testa Isevi, valde obliqua, aatioe tumida et truucata, postice compressa rotuadaque ; valvulis crassis, au- 

 tice crassioribus ; natibus tumidis, elevatis iacui-vatis terminalibusqiie ; epidermide tenebroso-fusca, 

 transverse et erebrivittata ; dentibus cardinalibus subgrandibus, striatis corrugatisque ; lateralibus 

 loagis, crassis, corrugatis subcurvisque ; margarita argentea et irideseeate. 



Shell smooth, very oblique, swollen and truncate before, compressed and rounded 

 behind; valves thick, thicker before; beaks swollen, raised, incurved and terminal; 

 epidermis dark brown, transversely and thickly banded ; cardinal teeth rather large, 

 striate and roughened ; lateral teeth long, thick, roughened and somewhat curved ; 

 nacre silver white and iridescent. 



Proe. Acad. Nat. Sci.. 1861. p. 60. 



Hob. — Coosawattee River, Ala., Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. 1, Length 1-2, Breadth 2-1 inches. 



Shell smooth, very oblique, swollen and truncate before and compi-essed and 

 rounded behind ; substance of the shell thick, thicker before ; beaks swollen ; eleva- 

 ted incurved and terminal ; ligament rather large, thick and light brown ; epidermis 

 dark brown, transversely and closely banded along the numerous lines of growth, 

 shining above and striate below ; umbonial slope rounded ; posterior slope slightly 

 raised, elongate, heart-shaped, with an obscure impressed line from the beak to the 

 posterior margin in each valve ; cardinal teeth rather large, striate, corrugate and 

 nearly parallel with the lateral tooth ; lateral teeth long, thick, corrugate, slightly 

 curved and nearly horizontal; anterior cicatrices distinct, small and deeply im- 

 pressed; posterior cicatrices distinct, rather small and well impressed; dorsal cica- 

 trices placed above the centre of the cavity of the beaks ; cavity of the shell shallow 

 and wide ; cavity of the beaks shallow and rounded ; nacre silver white and irides- 

 cent. 



Remarks. — I have several specimens before me of different ages, all bearing the 

 same character of numerous close ti'ansverse bands along the lines of growth. It is 

 closely allied to declsm (nobis,) but may be distinguished by its close lines of growth 

 and having more elevated beaks. On the other side it is allied to clavus, Lam., but it 

 is not rayed like that species, nor has it the same tiatness before the umbonial slope. 

 The coloring matter in the epidermis in this species seems to be expended in the 

 markings of the lines of growth. The anterior slope is sharply truncate, and has a 

 w^'ll-de'fined cordate impre.ssion. 



