l'NITEI> STATES. 75 



Remarks. — Two specimens only were found by Bisliop Elliott. They are both be- 

 fore me. It is among the smallest of the Uniones, and seems to be very rare. Both 

 arc females, and that figured shows the enlargement of the posterior portion about 

 the umbonial slope, incidental to the female in so many species. The margin of this 

 portion is disposed to be dentate. It is very nearly of the outline and general form 

 and polish of Haysianus, (nobis,) but is yellow, smaller, has less dentation on the margin 

 and it cannot be confounded with that species. It is the only very bright yellow spe- 

 cies I know of so diminutive a size. 



Unio Columbensis. pi. 14, fig. 55. 



Testa lajvi, oblongfi, siibinflata, valde inasquilatcrali, postice angulata ; valvulis subcrassis ; natibus prominu- 

 lis, concenti'icis undulatis; epidermide tcnebroso-fusea ; dentibus cardinalibus subgrandibus, elevatis, 

 acuminatis crenulatisque ; lateralibus praclongis, lamellatis subrectisquc ; margarita alba, et iridescente. 



Shell smooth, oblong, rather inflated, very inequilateral, angular behind; valves 

 rather thick; beaks somewhat prominent and concentrically inidulate ; epidermis 

 dark brown ; cardinal teeth rather large, elevated, acuminate and crenulate; lateral 

 teeth very long, lamellar and nearly straight ; nacre white and iridescent. 

 Proc. Acad. Xat. Sci. 18.57, p. 31. 



Hah. — Creeks near Columbus, Georgia. Bishop Elliott. 



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

 Diam. 11, Length 1-7, Breadth 35 inches. 



Shell smooth, oblong, rather inflated, very inequilateral, angular behind and 

 rounded before, carinate on the posterior slope ; substance of the shell rather thick ; 

 beaks somewhat prominent and concentrically undulate at tip ; ligament very long 

 and thin ; epidermis dark brown, in the young yellowish brown, transversely very 

 much striate ; cardinal teeth rather large, elevated, pointed, crenulate and disposed to 

 be double in both valves ; lateral teeth very long, lamellar and nearly straight ; 

 anterior cicatrices distinct, the smaller one being larger than usual ; posterior cicatri- 

 ces confluent ; dorsal cicatrices placed in the centre of the cavity of the beaks; cavity' 

 of the shell rather deep ; cavity of the beaks rather shallow and subangular ; nacre 

 white and iridescent. 



S(ift jwrts. — Branchial u(crv--< . Neither of the specimens before me have 



charged branchial ovisacks, but two are females and have ova in the ovarium. Bran- 

 chio' large, thin, inner one much the larger, free two thirds the length of abdominal 

 sack. Palpi very large, larger than in ohesufi, thin, triangular and united half down 

 the posterior edges. Mantle thickened and double along the edge, not colored except 

 at siphonal openings. Branchial opening rather large, with small brownish papilla? on 

 the inner edges. Anal ojwninr/ large, with very minute papilknc on the inner edges. 

 Super-anal openin// very large, edges not colored, united below for a short distance. 

 Color of the mass whitish. 



/?«»(«/ r/i-.s'. — This species belongs to that group of which rJ>e.sii.s, (nobis,) may be con- 



