NEW UNIONIDiE OF THE UNITED STATES. 7-5 



as it is in the left, and the interspace between the teeth form quite an arch. I name 

 this after Dr. Showalter, to whom I am greatly indebted for many fine specimens of 

 the Molluscs from Alabama. 



Unio dolosus. PI. 9, fig. 224. 



Testa laevi, obovata, subalata, subcompressa, ad latere planulata, postice et autice rotundata, valde inoei|ui- 

 laterali ; valvulis subtenuibus ; natibus prominulis, ad apices minute undulatis ; epidermidc virido- 

 oliva et obsolete radiata ; dentibus cardinalibus parvis, compressis crenulatisque ; lateralibus longi.s, 

 lamellatis subcurvisque ; margarita albida et purpurea paulisper tincta et valde iridescente. 



Shell smooth, obovate, scarcely winged, rather compressed, flattened at the sides, 

 rounded before and behind, very inequilateral ; valves rather thin ; beaks a little 

 prominent and minutely undulate ; epidermis greenish olive and obscurely rayed ; 

 cardinal teeth small, compressed and crenulated ; lateral teeth long, lamellar and 

 somewhat curved; nacre whitish, slightly tinted with purple and very iridescent. 

 Proc. Acad. Nat. Sci. 1S60, p. 307. 



Hub. — Alabama River, at Claiborne, Ala., Judge Tait. Coosa River, E. D. Showal- 

 ter, M. D. 



My cabinet and cabinet of Dr. Showalter. 

 Diam. - 8, Length 1'4, Breadth 2 - 3 inches. 



Shell smooth, obovate, scarcely winged, rather compressed, flattened at the sides, 

 rounded before and behind, very inequilateral ; substance of the shell thin ; beaks a 

 little prominent and minutely undulate ; ligament rather long, rather thin and light 

 brown ; epidermis greenish olive and obscurely rayed, with distant marks of growth ; 

 umbonial slope rather low and rounded ; posterior slope raised, compressed, with three 

 dark lines on each valve ; cardinal teeth small, compressed, crenulate and disposed to 

 be double in both valves; lateral teeth long, lamellar and somewhat curved; anterior 

 cicatrices distinct, rather large, well impressed ; posterior cicatrices confluent, large, 

 very slightly impressed ; dorsal cicatrices placed in a row across the cavity of the 

 beaks ; cavity of the shell shallow and wide ; cavity of the beaks rather shallow and 

 angular ; nacre wbitish, slightly tinted with purple and very iridescent. 



Soft Parts. — Branchial uterus fully charged, and occupying the posterior half of the 

 outer leaves of the branchiae, much as in the form o£cariosics, Say, being nearly oval, 

 and the ovisacks coming below the edges of the branchiae. Bronchia large, nearly 

 semicircular, inner one much the larger, united the whole length of abdominal sack. 

 Palpi large, falcate, united more than half way down the posterior edges. Mantle 

 very thin, thickened on the edges and fringed below the branchial opening. Branchial 

 opening rather small, with numerous minute papillae on the inneredges. Anal opt ning 

 small, with very numerous minute papillae. Super-anal opening rather long, colored 

 mi l lie edtnjs and united below. Color of the mass whitish. 



*& v 



