﻿202 NEW UNIONID^ OF THE 



Shell smooth, elliptical, rather inflated, inequilateral, rounded behind ; valves 

 rather thin, thicker before; beaks a little prominent, undulate at the tips; epidermis \ 

 yellow, polished, very much radiated ; cardinal teeth rather large, erect, somewhat 

 conical and crenulate ; lateral teeth rather long, lamellar and nearly straight ; nacre 

 either white or rose-color and very iridescent. 

 Proc. Acad. Nat. Sci., 1857, p. 32. 



Hob. — Othcalooga Creek, Gordon County, Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 



Diam. - 7, Length 1*1, Breadth 1-8 inches. 



Shell smooth, regularly elliptical, rather inflated, inequilateral, rounded behind ; 

 substance of the shell rather thin, thicker before; beaks a little prominent, with a 

 few rugose undulations at the tips ; ligament rather short, somewhat thin and brown ; 

 epidermis yellow, polished, very much radiated and with distant marks of growth ; 

 umbonial slope raised and very much rounded ; posterior slope not much raised and 

 quite broad ; cardinal teeth rather large, erect, somewhat conical and crenulate, 

 disposed to be double in both valves ; lateral teeth rather long, lamellar and nearly 

 straight ; anterior cicatrices distinct and moderately well impressed ; posterior 

 cicatrices confluent ; dorsal cicatrices placed across the centre of the cavity of the 

 beaks ; cavity of the shell rather deep and rounded ; cavity of the beaks shallow and 

 subangular; nacre white or rose-color and very iridescent. 



Soft parts. — Branchial uterus occupies the posterior half of the outer branchiae, very 

 much like U. cariosus Say. The two specimens under examination have, the one 

 nine the other twelve branchial ovisacks charged, which are rather long and very wide. 

 They were full of embryos ready to be extruded. The lower border of these branchial 

 ovisacks is very much enlarged and of a purplish tint. Branchial rather large and 

 rounded below, the inner ones much the larger before, united the whole length of 

 abdominal sack. Palpi rather small, thin, subtriangular and united above at the 

 posterior edges. Mantle thin, much thickened on the margin, which, below the 

 branchial opening, is deep brown and furnished with large dark papillae to the middle 

 of the basal line. Branchial opening rather large, with numerous small, dark papill'as 

 on the inner edges. Anal opening rather small, with numerous very small dark 

 papillae. Super-anal opening large, dark inside and united below for a short distance. 

 Color of the mass whitish. 



Embryonic shell is elongate pouch-shape, rather flattened on the side and very closely 

 resembling that of U. rutilans (nobis,) pi. 5, fig. 4. 



Remarlcs. — I have the advantage of having four specimens of this .pretty little 

 species before me. It is nearly allied to concavus (nobis), being yellow, having dark 

 green rays and of nearly the same outline, but it may be easily distinguished from 

 it by its being a smaller species, the beaks being more terminal and the form 

 inclining more to obovate. The rays too are broader and more distinct. The cardinal 



