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gular, rather thin, united but a short distance down the posterior edges. Mantle thin, 

 thickened along the edge, deeply colored, nearly black along the posterior margin , 

 which, has numerous dark brown papillae on the edge for some distance below the 

 branchial opening. Branchial opening large, with numerous small brown papillae on 

 the inner edges. Anal opening rather large with numerous very minute light brown 

 papillae on the inner edges. Super-anal opening rather large, edge slightly colored, 

 united below. Color of the mass whitish. 



Remarks. — Seven or eight specimens were received from Bishop Elliott, in alcohol. 

 This species is nearly allied to U. exiguus, (nobis,) but is more regularly oval, more 

 inflated, browner, and has larger cardinal and lateral teeth. The exiguus is not brown 

 like this, but green, and much rayed. They are both delicate species. The epider- 

 mis about the middle of the outside of the valve is usually bright and polished. It 

 is of an unusually regular ellipse. 



Unio fullatus. PI. 8, fig. 39. 



Testa loevi, obliquo-transversa, paulisper inflata, valde insequilaterali ■ valvulis crassis ; natibus prominulis, 

 ad apices undulatis ; epidermide vel tenebroso fusca vel nigra; dentibus cardinalibus curtis, crassis, 

 in utroque valvulo duplicibus ; lateralibus crassis, longis subrectisque ; ruargarita vel purpurea vel sal- 

 monis colore tincta et iridescente. 



Shell smooth, obliquely transverse, somewhat inflated, very inequilateral ; valves 

 thick ; beaks a little prominent, undulate at the tip ; epidermis dark brown or black ; 

 cardinal teeth short, thick, double in both valves; lateral teeth thick, long and erect; 

 nacre purple or salmon color and iridescent. 

 Proc. Acad. Nat. Sci. 1856, p. 262. 

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

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

 Diam. l'l, Length T7, Breadth 3*4 inches. 



Shell smooth, obliquely transverse, somewhat, inflated, very inequilateral, rounded 

 before, subangular behind ; substance of the shell thick, thicker before ; beaks a little 

 prominent, rugosely undulate at the tip ; lines of growth distant ; ligament rather 

 long and somewhat stout ; epidermis very dark brown or black, usually bright on the 

 sides, in the young obscurely radiate ; umbonial slope obtusely angular ; cardinal teeth 

 short, thick, striate, disposed to be double in both valves ; lateral teeth thick, long, 

 erect, nearly straight, single in the right and double in the left valve ; anterior cica- 

 trices distinct and deeply impressed ; posterior cicatrices confluent ; dorsal cicatrices 

 placed in the cavity of the beaks posterior to the cardinal tooth ; cavity of the shell 

 rather shallow ; cavity of the beaks shallow and angular ; nacre usually salmon in 

 the cavity and purple on the border and iridescent. 



Soft Parts. — Branchial uterus spread out on the whole length of the outer branchiae. 

 Branchiae not very large, very transverse, inner ones somewhat the larger, gently 



curved below, free two-thirds the length of abdominal sack. Palpi very small, oblique, 



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