gula,!-, rather tliiii, united Imt ii short distaii h)\vM the posterior cdgos. Mantle thin. 



thickened along tlie edge, deeply colored, nearly hlack along the posterior uiargiii, 

 which has numerous dark brown papilla3 on the edge for some distance below the 

 branchial opening. Branchial opening large, with numerous small brown papilla^ on 

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

 papilla) on the inner edges. Super-anal openinri rather largo, edge slightly colored, 

 united below. Color of the mass whitish. 



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

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

 inflated, browner, and has larger cardinal and lateral teeth. The exigum 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. 



Uixio ruLLATus. PI. 8, fig. 39. 



T('sf:"i lajvi, obliqiio-transversa, paulisper inflata, vald6 iniioquilaterali; valvulis crassis ; iiatibus prominulis, 

 ad apices undulatis ; cpiderniide vel tenebroso-fuacS, vel nigra; dentibus cardinalibus curtis, crassis, 

 in utroque valvuio duplicibus; lateralibus crassis, longis subrectisque ; inargaritd. vel purpurea vel sal- 

 nionis 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. 11, Length 1-7, Breadth ;]-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 uter^is spread out on the whole length of the outer branchiae 

 Bronchia' not very large, very transverse, inner ones somewhat the larger, gently 

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



