﻿UNITED STATES. 87 



Unio viridicatus. PL 18, fig. 67. 



Testa lasvi, suboblcmga, subcompressa, postice compressa, biangnlata, valde inaequilaterali, valvulis subtenui- 

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

 cardinalibus parvis ; subcompressis crenulatisque ; lateralibus prgelongis, lamellatis subrectisque; mar- 

 garit& cseruleo-alba et iridescente. 



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

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

 rugosely 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. 



flab. — 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, very 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. Branchiaz 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 papillse 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. 



Remarks. — 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. 



