UNITED STATES. 63 



shell not very deep ; cavity of the beaks rather shallow and subangnlar ; nacre silver 

 white and iridescent. 



Soft Parts. — Branchial uterus . Branchim very large, inner ones much the larger; 



much curved below, attached the whole length of the abdominal sack.* Palpi very 

 large, angular below, not attached on the posterior edge. Mantle thin, thicker on the 

 margin and colored on the edges. Branchial opening rather large, with black papillae 

 on the inner edges. Anal opening rather small, with small nearly black crenulations 

 on the inner edges. Super-anal opening very long, dark on the inner edge and united 

 below for a short distance. Color of the mass whitish. 



RemarJcs. — Several specimens were received from Bishop Elliott in alcohol, but no 

 female individual. It is nearly allied to rutilans, (nobis,) but is a much thicker shell, 

 with a whiter nacre, and larger and more tubercular cardinal teeth, that in the left 

 valve having the anterior lobe much the larger. The lateral teeth are also much 

 thicker. The outline is nearly of a regular ellipse, but enlarged at the basal margin. 

 The specimen figured is probably a female, the part before the umbonal slope being 

 enlarged. 



Unio geminus. pi. 10, fig. 45. 



Testa Irevi, elliptica, inflatu, valde inoequilaterali ; valvuHs crassis ; natibus prominulis; cpidermide tene- 

 broso-castanea, obsolete^ radiatu, ad umbones polite ; dentibus cardinalibus magnis, acuminatis, in 

 utroque valvule duplicibus ; lateralibus longis, crassis subcurvisque ; luargarita purpurea et iridcscente. 



Shell smooth, elliptical, inflated very inequilateral ; valves thick ; beaks a little 

 prominent ; epidermis dark chestnut ; obscurely radiated, polished at the umbones ; 

 cardinal teeth large, pointed, double in both valves ; lateral teeth long, thick and 

 somewhat curved ; nacre purple and iridescent. 

 Proc. Acad. Nat. Sci., p. 262. 



Hab. — Buckhead Creek, Burke Co., Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. 1-2, Length 1-7, Breadth 2-9 inches. 



Shell smooth, elliptical, inflated, very inequilateral, rounded before, subbiangular 

 behind ; substance of the shell thick, rather thinner behind ; beaks a little prominent ; 

 ligament rather short and somewhat stout ; epidermis dark chestnut brown, polished 

 on the side and rather roughly striate towards the margin, very obscurely rayed, 

 with not very distant lines of growth ; cardinal teeth large, pointed, crenulate, double 

 in both valves ; lateral teeth long, thick, lamellar and somewhat curved ; anterior 

 cicatrices distinct and deeply impressed ; posterior cicatrices confluent ; dorsal cica- 

 trices rather small, and placed in the centre of the cavity of the beaks ; cavity of 



*0n each side along the attachment of the inner branchiie with the abdominal sack, there were two small 

 blind ponchos, which at first I thought led to the upper cavity, but they were not opened through, and I pre- 

 sume were the nidus of some parasite. 



