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ART, XXII. — Descriptions of New Fresh Water mid Marine Shells. 



By T. A. Conrad. 



Of the following fresh water shells, those from Georgia were kindly loaned me for 

 description by J. Hamilton Couper, Esq. 



UNIO. 



U. SECURiFORMis. PI. 37, fig. 1. — Suborbicular, thick, compressed; valves slightly convex; umbo 

 flattened, marked with obtuse, narrow, divaricated plaits ; plaits on the lower half of the valves 

 obscure and interrupted ; umbonal slope rounded ; posterior slope with strong oblique plaits towards 

 the apex ; beaks eroded ; epidermis black ; within white ; cardinal teeth large, direct, profoundly 

 sulcated. 



Proceed. Acad. Nat. Sc, Vol. iv., p. 152. 

 Inhabits Flint River, Georgia. 



U. STAGNALis. PI. 37, fig. 2. — Widely elliptical, ventricose, rather thin ; towards the posterior extremity 

 very thin and fragile ; anteriorly regularly rounded ; posteriorly somewhat pointed, with an acutely 

 rounded extremity ; basal margin regularly curved ; summits prominent, eroded ; posterior margin very 

 oblique and nearly straight ; epidermis ochraceous and olivaceous; rays green, not very distinct on the 

 middle and anterior side, but more so posteriorly, some rather broad, others linear; posterior slope dark 

 colored, rayed ; within white and highly iridescent posteriorly ; cardinal teeth much compressed and 

 oblique, double in each valve ; lateral teeth very slightly curved, finely granulated. 

 Proceed. Acad. Nat. Sc, Vol. iv., p. 152. 

 Inhabits mill ponds ; Ogeechee River, Georgia. 



U. Ogeecheensis. pi. 37, fig. 3, 4. — Elliptical, thin, inflated ; posterior side somewhat pointed, extremity 

 subangular; valves slightly contracted from beak to base; summits rather prominent, decorticated, 

 slightly undulated ; epidermis ochraceous with interrupted green rays, some of them broad ; within 

 white, highly iridescent posteriorly ; cardinal teeth oblique, compressed ; lateral teeth rectilinear. 

 Proceed. Acad. Nat. Sc, Vol. iv., p. 153. 

 Allied to the preceding, but has a lighter colored epidermis with more distinct rays; 

 is proportionally longer ; the cardinal tooth in the left valve is longer and less lobed, 

 and the lateral teeth are straight, without granules, and less oblique than in the 

 preceding species, which is a larger shell. 



U. EOSACEus. PI. 37, fig. 5. — Widely elliptical, ventricose above ; posterior margin obliquely truncated, 

 slightly sinuous ; extremity subangular or acutely rounded ; epidermis ochraceous and dark brown : 

 rays indistinct, frequently broad, but composed of fasciculi of lines; surface with tine radiating wrinkles ; 

 within deep rose-purple ; cardinal teeth prominent, oblique, compressed, trifid, or three teeth in the 

 left valve. 



Proceed. Acad. Nat. Sc, Vol. iv., p. 153. 



Inhabits Savannah River. Allied to U. ochraceus, Say. 



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