﻿UNITED STATES. 231 



embryos in the outer branchiae. This had them perfected and only filling the anterior 

 third, so that these branchial uteri presented the appearance of having discharged 

 more than half the young, the part not charged presenting a colored mass. BrancMce 

 large, nearly semicircular, inner ones the larger on the anterior ends, free nearly 

 half the length of abdominal sack. Palpi rather large, suboval, united but a short 

 distance on the posterior edges. Mantle thin and delicate, thickened at the border. 

 Branchial opening large, blackish within and without, with numerous, reddish papillae 

 on the inner edges. Anal opening black within, edges reddish, without papillae. 

 Super-anal opening rather small, edges slightly colored, united for some distance below. 

 Color of the mass whitish. 



Embryonic shell light brown, subtriangular, and very near to An. undulata (nobis) in 

 outline. 



Remarks. — I have the advantage of examining ten specimens of different ages. It 

 is nearly allied to fluviatilis, but is more inflated over the umbonial slope and not 

 quite so transverse, nor has it so smooth an epidermis. On the other side it leans 

 towards gibbosa Say, but is not so much inflated over the umbonial slope. It will 

 also call to mind Stewartiana (nobis), but it is more transverse and has a smoother 

 epidermis. In several of the young specimens in my possession the ligament is 

 concealed. 



Anodonta Gesnerii. PL 31, fig. 109. 



Test! lsevi, elliptic!, valde inflate, postice* subangulata, antice" sulcata, valde insequilaterali ; valvulis 

 subcrassis ; natibus prominentibus, tumidis ; epidermide valde polita, vel viridi vel lute!, obsolete 

 radiata ; margarita vel alba vel aurea et iridescente. 



Shell smooth, elliptical, very much inflated, subangular behind, sulcate before, very 



inequilateral ; valves rather thick ; beaks rather prominent, swollen ; epidermis very 



much polished, greenish or yellowish, obsoletely rayed ; nacre either white or golden 



and iridescent. 



Proc. Acad. Nat. Sci., 1858, p. 139. 



Blab. — Uphaupee Creek, Macon County, Alabama. Wm. Gesner, of Milledgeville, 

 Georgia. 



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

 Diam. 1-8, Length 2*5, Breadth 4-7 inches. 



Shell smooth, elliptical, very much inflated, subangular behind, sulcate before, very 

 inequilateral ; substance of the shell rather thick ; beaks rather prominent and swollen ; 

 ligament rather long, moderately thick and light brown ; epidermis very smooth and 

 much polished, greenish or yellowish, obsoletely rayed, with very distant lines of 

 growth ; umbonial slope raised and rounded ; posterior slope large, with two dark 

 rays passing from the beaks to the posterior margin ; anterior cicatrices large, confluent 



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