50 NEW UNIONID.E OF THE 



and slightly impressed ; posterior cicatrices confluent and very slightly impressed ; 

 cavity of the shell very deep and very wide; cavity of the beaks somewhat deep and 

 rounded ; nacre white or golden and iridescent. 



Remarhs. — This is a very fine species, which is found as wide as seven and a half 

 inches. It reminds one of J., cygnea Lam., but is mox'e ponderous and more inflated. 

 It is rather more transverse than fluvlatilis, which sometimes is nearly as large. 

 Young specimens remind one of Dunlapiana (nobis), from South Carolina. The 

 nacre is remarkably rich, and in some specimens it has a soft, satin, golden hue. 

 The old individuals are disposed to be much thickened along the margin. Some 

 specimens are very much sulcate on the anterior portion and have yellow and green 

 bands. The posterior slope is usually dark. It is to be regretted that we have not 

 the opportunity of examining the soft parts of this species. None were received in 

 alcohol. I dedicate this fine species with pleasure to Mr. William Gesner, to whom 

 I am indebted for many fine Unionidce of Georgia. 



Anodonta IIallenbeckii. pi. 32, fig. 112. 



Testa sulcata, ad basin subarcuatii, vald^ inflata, postie^ et antice rotundata, inequilaterali ; valviilis 

 subtenuibus, antice paulisper crassioribus ; natibus prouiinentibus, tumidis ; epidermide micante, vel 

 luteavel tenebroso-oliva, eradiata; margarita alba et iridescente. 



Shell sulcate, subarcuate at the base, very much inflated, rounded behind and 

 before ; inequilateral ; valves rather thin, slightly thicker before ; beaks rather 

 prominent, swollen ; epidermis shining, yellow and dark olive, without rays ; nacre 

 white and iridescent. 



Proc. Acad. Nat. Sci., 1858, p. 138. 



Hub. — Uphaupee Creek, Macon County, Georgia. W. Gesner. 



My cabinet and cabinet of Mr. Gesner, Mr. Hallenbeck and Dr. Lewis. 

 Diam. 1-5, Length 2-2, Breadth 4 inches. 



Shell sulcate, subarcuate at base, very much inflated, rounded behind and before, 

 inequilateral ; substance of the shell rather thin, slightly thicker before ; beaks rather 

 prominent, swollen ; ligament rather long, thick and dark brown ; epidermis shining, 

 yellow or dark olive, without rays, with distant marks of growth ; umbonial slope 

 raised and rounded ; posterior slope slightly raised, dark and striate ; anterior cicatrices 

 large, confluent and slightly impressed ; posterior cicatrices confluent, large and very 

 slightly impressed ; dorsal cicati'ices placed in the centre of the cavity of the beaks ; 

 palleal cicatrix broad, but very indistinct ; cavity of the shell deep and broad ; 

 cavity of the beaks shallow and obtusely angular ; nacre white and iridescent. 



Remarhs. — This species is nearest allied to Gesnerii (nobis), but may be distin- 

 guished at once by the sulcations of the surface and the emargination of the basal line. 

 The youngest of four specimens before me is not emarginate, but would no doubt 



