nNITKD STATES. 87 



Unio vikidicatus. pi. 18, fig. 07. 



Testa Irevi, suboblongrt, subcompressa, poatici comprcssa, biangnlata, valde in.icquilaterali, valvulis subtcnui- 

 bus ; natibus prominulis, ad apices rugoso-undulatis ; epidermide virescentc, polita, eradiata ; dentibus 

 cardinalibus parvis, subcompressis crenulatisque ; lateralibus prsolongis, lamellatis subrectisquej mar- 

 garita cwrulco-albu et iridescentc. 



Shell smooth, somewhat oblong, rather compressed, flat and biangular behind ; 

 very inequilateral; valves rather thin; beaks slightly prominent, at the beaks 

 rugoselj' undulate ; epidermis greenish, polished and without rays ; cardinal teeth 

 small, rather compressed and crenulate ; lateral teeth very long, lamellar and nearly 

 straight ; nacre bluish white and iridescent. 

 Proc. Acad. Nat. Sci., 1857, p. 170. 



Hah. — Buckhead Creek, Burke County, Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. -9, Length 1-7, Breadth 3-1 inches. 



Shell smooth, somewhat oblong, rather compressed, biangular, compressed behind and 

 round before, verj' inequilateral ; substance of the shell rather thin, slightly thicker 

 before ; beaks slightly prominent, rugosely undulate at the tip ; ligament long and 

 thin ; epidermis greenish inclining to olive, without rays, shining on the umbones and 

 striate towards the margin ; umbonial slope slightly raised into an obtuse angle ; car- 

 dinal teeth small, rather compressed, crenulate, pointed, single in the right and double 

 in the left valve ; lateral teeth very long, lamellar and nearly straight ; anterior cica- 

 trices rather large, distinct and impressed ; posterior cicatrices confluent, and rather 

 large ; dorsal cicatrices placed across the centre of the cavity of the beaks ; cavity of 

 the shell very shallow and wide ; cavity of the beaks shallow and rounded ; nacre 

 bluish white and iridescent. 



Soft Parts. — Branchial uterus not charged, but ova were found in the ova- 

 rium. BrancMoi thin, very wide, rounded below, inner ones much the larger, free 

 more than half the length of abdominal sack. Palpi very small, thin, oblique, sub- 

 angular, very wide on the upper portion and united only at the upper part of the 

 posterior edge. Mantle very thin, with a rather thin broad border. Branchial opening 

 large, with numerous small dark brown papilla; on the inner edges. Anal opening 

 very large, with very minute brown papillae on the inner edges. Super-anal opening 

 very large, slightly colored on the inner edges and united below for a small distance. 

 Color of the mass whitish. 



Remarlcs. — Several specimens were received from Bishop Elliott, and that figured 

 is a female. It belongs to the complanatus group, and is very near to the thin white 

 compressed varieties of that species. All the specimens had a white nacre. A single 

 one was indistinctly rayed. 



