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NKW UNIONID.E OF THE 



Unio sudus. pi. 21, fig. 77. 



Testa liBvi, elliptica, subinflata, postice obtuse angulata, inxquilaterali ; valvulis subtenuibus, antit4 

 crassioribus ; natibus subprominentibus, ad apices undulatis ; epidermide luteola, valde radiata, nitida ; 

 dentibus cardinalibus parvis, compressis, lamellatis, in utroque valvule duplicibus ; lateralibus sub- 

 longis, lamellatis subrectisque ; margarita vel alba vel salmonis colore tincta et valdfe iridescente. 



Shell smooth, elliptical, rather inflated, obtusely angular behind, inequilateral ; 

 valves rather thin, thicker before ; beaks rather prominent, undulate at the tips ; 

 epidermis yellowish, very much radiated, polished ; cardinal teeth small, compressed, 

 lamellar, double in both valves; lateral teeth rather long, lamellar and nearly 

 straight ; nacre white or salmon color and very iridescent. 

 Proc. Acad. Nat. Sci., 1857, p. 170. 



Hah. — Dry Creek, near Columbus, Georgia, Bishop Elliott, and Macon, J. C. Plant. 



My cabinet and cabinet of Bishop Elliott. 

 Dijim. -7 Length 1, Breadth 1-S inches. 



Shell smooth, elliptical, rather inflated, obtusely angular behind and regularly 

 rounded before; substance of the shell rather thin, thicker before; beaks rather 

 prominent, with small, irregular undulations at the tips ; ligament small and light 

 brown ; epidermis yellowish, regularly radiated all over, the rays being green and 

 interrupted, polished and with distant marks of growth ; umbonial slope rather raised 

 and rounded ; posterior slope broad and slightly raised ; cardinal teeth small, com- 

 pressed, lamellar, double in both valves; lateral teeth rather long, lamellar and 

 nearly straight; anterior cicatrices distinct and rather large; posterior cicatrices 

 confluent; dorsal cicatrices in the centre of the cavity of the beaks; cavity of the 

 shell rather deep and wide; cavity of the beaks rather shallow and subangular; nacre 

 white or salmon color and very iridescent. 



Soft Parts. — Brancldal rtferas occupying the posterior half of the outer branchiae, 

 and charged in large sacks like TJ. cariosus Say, the inferior edge being blackish. 

 Brancldce. large, inner one the larger on the interior portion, nearly semicircular, free 

 for a very short distance at the end of the abdominal sack. Palpi rather large, sub- 

 oval and united at the upper part of the edges. Mantle thin, thickened at the margin, 

 with numerous rather distant well defined papilla3 for some distance below the 

 branchial opening. Branchial opejiing large, with numerous brownish papillae. 

 Anal opening small, with very minute papillas on the inner edges. Super-anal opening 

 small, united for some distance below. Color of the mass whitish. 



Emhrjjonic shell is the form which belongs to the group of the pouch-shape and is 

 somewhat elongate. 



Remarks. — This is a beautiful, rather small species, near to concavus (nobis and 

 Prevostianus (nobis). It is not quite so transverse as either. It is inflated like the 



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