76 NEW UNIONID.^; OF THE 



sidered the type. It seems to be nearest to camptodnn, Say, and approaches 

 symefricus, nobis. It is not so transverse as cam2)iodo7i, nor so elliptical as symetrims. 

 It is less angular behind than declivis, Say, and less inequilateral. The posterior 

 slope has well marked impressed lines from the beaks to the margin. It seems to be 

 entirely without rays, the epidermis being usually well covered with rough striae. 

 The lines of growth are distant. All the specimens which I have seen have white 

 nacre. The obesus is usually disposed to be of a dull purplish color. 



Unio apicinus. pi. 14, fig. 56. 



Testa laevi, elliptica, subcompressa, subasquilaterali, postice obtuse angulata; valvulis subtenuibus; natibus 

 prominulis, ad apices regulariter et decore undulatis ; epidermide fusco-lutescente, radiis minuti.s 

 indute ; dentibus cardinalibus parvalis, obliquis, compressis, siibacutis, in utroque valvule duplicibus 

 crenulatisque ; lateralibus sublongis, lamellatis subcurvisque ; margarita albida et iridescente. 



Shell smooth, elliptical, rather compressed, nearly equilateral, obtusely angular 

 behind; valves thin; beaks slightly prominent, at the tip regularly and beautifully 

 undulate ; epidermis yellowish brown and covered with small rays ; cardinal teeth 

 rather small, oblique, compressed, rather sharp, double in both valves and crenulate ; 

 lateral teeth rather long, lamellate and rather curved ; nacre whitish and iridescent. 

 Proc. Acad. Nat. Sci. 1857, p. 32. 



Hob. — Othcalooga Creek, Gordon County, Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. -4, Length -7, Breadth 1-2 inches. 



Shell smooth, elliptical, rather compressed, nearly equilateral, obtusely angular behind 

 and rounded before ; substance of the shell thin, a little thicker before ; beaks slightly 

 prominent at the tips, regularly and beautifully undulate, the undulations forming a 

 sharp angle in the middle ; ligament short and thin ; epidermis yellowish brown and cov- 

 ered with small nearly equidistant rays ; umbonial slope scarcely raised ; cardinal teeth 

 rather small, oblique, compressed, rather sharp, crenulate, double in both valves ; lateral 

 teeth rather long, lamellar and slightly curved ; anterior cicatrices distinct ; posterior 

 cicatrices confluent ; dorsal cicatrices placed on the underside of the plate posterior to 

 cardinal tooth ; cavity of the shell shallow ; cavity of the beaks shallow and angular ; 

 nacre white and iridescent. 



Soft Parts. — A male. Branchke thin, proportionately rather large, inner one much 

 the larger, much rounded below, free two-thirds the length of abdominal sack. Palpi 

 small, elongate, united but a small distance down the posterior edges. Mantle thin, 

 dark brown at siphonal openings and on the basal margin. Branchial opening rather 

 large, with small brownish papilloe on the inner edges. Anal opening large, with small 

 brownish papillre on the inner edges. Super-ayial opening small and colored on inner 

 edge, seems not to be united below. Color of the mass whitish. 



Remarlcs. — Only a single specimen, and that a male, here figured, was received. It 

 has nearly the outline of a young pullatvf: (nobis,) or radintuf!. Lam. This is probably 



