56 SUPPLEMENT TO ISAAC LEA'S PAPER ON TNIONIDiE. 



tional specimens I am satisfied that it is distinct. It may be distinguished by its 

 being more quadrate, of a darker epidermis, and having the marks of growth much 

 more close. None of these specimens have the beaks sufficiently perfect to display 

 the undulations of the tips. 



Unio hastatus. pi. 19, fig. 54. 



Testa Isevi, transversa, subcompressa, valde insequilaterali, postice angulata, antice rotunda; valvulis 

 crassiusculis, antice parum crassioribus ; natibus prominulis ; epidertnide luteo-oliva, obsolete 

 radiata; dentibus eardinalibus parvis, subcompressis crenulatisque ; lateralibus longis, lamellatis 

 subrectisque ; margarita alba et valde iridescente. 



Shell smooth, transverse, somewhat compressed, very inequilateral, angular 

 behind and round before ; valves somewhat thick, slightly thicker before; beaks 

 slightly raised ; epidermis yellowish-olive, obscurely rayed ; cardinal teeth small, 

 somewhat compressed and crenulate ; lateral teeth long, lamellar and nearly 

 straight; nacre white and very iridescent. 

 Proc. Acad. Nat. Sci., 18T3, p. 423. 



Hab. — New-Market, Abbeville District, South Carolina, Dr. L. R. Gibbs and 

 Dr. J. P. Barratt ; E.ocky Creek, near Macon, Georgia, J. C. Plant. 



My cabinet. 

 Diam. '6, Length 1*1, Breadth 2'5 inches. 



Shell smooth, transverse, somewhat compressed, very inequilateral, angular be- 

 hind, round before; substance of the shell somewhat thick, slightly thicker before; 

 beaks slightly raised; ligament long, thin and light brown; epidermis yellowish- 

 olive, obscurely rayed, with distant marks of growth ; umbonial slope very slightly 

 raised and rounded ; posterior slope narrow elliptical, slightly carinate ; cardinal 

 teeth small, somewhat compressed and crenulate ; lateral teeth long, lamellar and 

 nearly straight ; anterior cicatrices distinct, rather large and somewhat impressed ; 

 posterior cicatrices confluent, large and slightly impressed ; dorsal cicatrices placed 

 nearly in the centre of the cavity of the beaks ; cavity of the shell wide and very 

 shallow ; cavity of the beaks very shallow ; nacre white and very iridescent. 



Remarks. — Many years since I received two specimens of this species from 

 Prof. Gibbs, and shortly afterwards a single valve from the late Dr. Barratt. 



I was greatly in hopes of getting more and better specimens, but none have 

 been observed, to my knowledge. The outline is somewhat like that of Barrattii 

 (nobis), but that species is not so transverse, is darker in the epidermis and has 

 more rays. It is also a straighter shell It properly comes between Barrattii and 

 productus Con. It cannot be confounded with the latter shell. Neither specimen 

 has beaks perfect enough to display any undulations of the tips. 



