﻿UNITED STATES. 67 



transversely striate; cardinal teeth rather thick, double in both valves and crenulate ; 

 lateral teeth long and somewhat curved; nacre purple or salmon color and iridescente. 

 Proc. Acad. Nat. Sci. 1857, p. 31. 



Hab. — Creeks near Columbus, Georgia. Bishop Elliott and Dr. Lewis. 



My cabinet and cabinets of Bishop Elliott and Dr. Lewis. 

 Diam. 1, Length 1-4, Breadth 2-3 inches. 



Shell smooth, elliptical, inflated, inequilateral, regularly rounded before and very 

 obtusely angular behind ; substance of the shell rather thick, thicker before ; beaks 

 somewhat prominent ; ligament rather long and slender ; epidermis very dark, nearly 

 black, with rather close marks of growth, smooth and shining on the umbones and 

 transversely striate on the margin; umbonial slope round; cardinal teeth rather 

 small and thick, crenulate, double in both valves ; lateral teeth long, lamellar and 

 somewhat curved ; anterior cicatrices distinct and rather deeply impressed ; posterior 

 cicatrices rather small and confluent ; dorsal cicatrices placed in the centre of the 

 cavity of the beaks, cavity of the shell rather deep; cavity of the beaks rather deep 

 and angular; nacre beautifully salmon or purple and very iridescent. 



Soft Parts. — Branchial uterus situated in posterior part of the outer branchiae in 

 large ovisacks like cariosus, Say. Branchiae rather small, inner ones very much 

 the larger, nearly semicircular, united the whole length of the abdominal sack. Palpi 

 large, thin, suboval, united at the posterior edges only at the upper part. Mantle 

 thin, thicker at the margin, with colored rather sharp papillae below the branchial 

 opening for some distance. Branchial opening small, with numerous small brown 

 papillae on the inner edges. Anal opening very small, with very small brown spotted 

 papillae. Super-anal opening rather small, colored on the edges, united below. Color 

 of the mass whitish. 



Embryonic shell elongate pouch-shape ; color clear white. 



Remarhs. — Many specimens of this very beautiful species were sent to me by 

 Bishop Elliott and other friends, but none were with perfect beaks, so that I know 

 not if they be undulate. It is near to subellipsis (nobis,) but is a smaller species, 

 and I have never seen any one with a white nacre, while subellipsis is I believe 

 always white. In the epidermis it is darker, has no rays and is disposed to be trans- 

 versely furrowed. The specimen figured is a male. The female is very obtuse at 

 the posterior end and much inflated on the umbonial slope. The nacre is remarkably 

 fine. In very perfect specimens it is beautifully, and usually intensely, colored, and 

 satin like. 



Unio extensus. PI. 12, fig. 49. 



Testa lasvi, valde transversa, valde compressa, ad latere planulata, valde inacquilaterali, postice subangu- 

 lata; valvulis subcrassis; natibus prominulis ; cornpressis ; epidermidc tencbroso-fusca, transverse 

 striata ; dentibus cardinalibus subcrassis, acuininatis ; latcralibus praslongis, rectis, postice incrassatis ; 

 margarita alba et iridescente. 



