CHIEFLY OF THE UNITED STATES. 257 



- Shell smooth, widely elliptical, rather compressed, very inequilateral, subbiangular 

 behind, round before ; valves rather thin, somewhat thicker before ; beaks a little 

 prominent; epidermis dark brown, obscurely rayed ; cardinal teeth very small, oblique 

 and striate ; lateral teeth very long and slightly curved ; nacre bluish white or salmon 

 and very iridescent. 



Proc. Acad. Nat. Sci. 1865, p. 88. 



Hah. — North Carolina, Prof. E. Emmons. 



My cabinet and cabinet of Prof. Emmons. 



Diam. -4, '" Length -8, Breadth TC inch. 



Shell smooth, widely elliptical, somewhat compressed, very inequilateral, subbi- 

 angular behind, round before ; substance of the shell rather thin, somewhat thicker 

 before ; beaks a little prominent ; ligament rather long and thin ; epidermis dark 

 brown, obscurely rayed and with distant marks of growth ; umbonial slope slightly 

 raised and obtusely angular ; posterior slope very narrow, elliptical and slightly cari- 

 nate ; cardinal teeth very small, oblique and striate ; lateral teeth very long and 

 slightly curved; anterior cicatrices distinct, rather large and well impressed; poste- 

 rior cicatrices confluent, rather small and slightly impressed ; dorsal cicatrices placed 

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

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

 and very iridescent. 



Remarhs. — This is a small species nearly allied to aquilus (nobis) in outline, but is 

 very much smaller. In the color of the epidermis and in the small obscure rays 

 they are very much alike. None of the five specimens before me have beaks perfect 

 enough to ascertain the class of undulations of the tips. Aquilus, which this species 

 closely resembles, is from Flint River, Georgia. This is one of the many new species 

 collected by my friend, the late Professor Emmons, to whom I am so much indebted 

 for this and other favors. 



Unio amabilis. pi. 31, fig. 72. 



Testa Itevi, triangiilari, micanti, subinflata, iiiffiquilaterali, postiee angulata, autice rotunda ; valvulis 

 crassiusculis, autice crassioribus; natibus subprominentibus, ad apices undulatis; epidermide vel 

 luteola vel fiiscescente, obsolete radiata; dentibus cardiualibus parvis, obliquis, subcompressis ; 

 lateralibus sublongis, obliquis corrugatisque ; margarita vel alba vel dilute saloiouea et valde 

 iridescente. 



Shell smooth, triangular, shining, rather inflated, inequilateral, angular behind, 

 round before ; valves somewhat thick, thicker before ; beaks somewhat prominent, 

 undulate at the tips ; epidermis yellowish or brownish, obscurely radiate ; cardinal teeth 

 small, oblique, somewhat compressed; lateral teeth rather long, oblique and corru- 

 gate ; nacre white or pale salmon and very iridescent. 

 Proc. Acad. Nat. Sci. 1865, p. 89. 



