12 DESCRIPTIONS OF 



Shell smooth, elliptical, iiitiated, nearly equilateral, obtusely angular behind ; valve 

 thick ; beaks somewhat prominent ; epidermis yellow, polished ; cardinal teeth thick 

 and short ; lateral teeth short, rather thick and nearly straight ; nacre white, irides- 

 cent. 



Proc. Acad. Nat. Sci. Vol. 8, p. 93. 



Hob. — Newville, Burmah. Mrs. Vinton. 



Cabinet of Mr. W. A. Haines, New York. 

 Diam. -7, Length 1, Breadth 1-4 inch. 



Shell smooth, elliptical, inflated, nearly equilateral, obtusely angular behind and 

 rounded before ; substance of the shell thick, thinner behind ; beaks somewhat promi- 

 nent, nearly medial ; ligament rather short ; epidermis olive yellow, smooth and 

 polished; umbonial slope subangular ; cardinal teeth large, thick and short ; lateral 

 teeth short, rather thick and nearly straight ; anterior cicatrices distinct ; posterior 

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

 cavity of the shell rather deep and rounded ; cavity of the beak rather shallow and 

 angular ; nacre white and iridescent. 



Remarks. — A single specimen only of this species was received by Mr. Haines. In 

 outline it is most like to Z7. Tavoyensis, Gould, but it differs in being without folds, being 

 yellow and not so much inflated towards the beaks. It also resembles U. corrugatus, 

 Retz., but is not corrugate, nor is it quite so transverse. It differs also in color. 

 The tips of the beaks being eroded in this specimen, I am unable to say if there be 

 any undulations there in perfect individuals. 



Unio geavidus. pi. 24, fig. 5. 



Testa alata, lasvi, triangulari, valde inflata, valde inaequilaterali ; valvulis tenuibus ; natibus elevatis, tumidis ; 



epidermide lutea, nitida ; dentibus cardinalibus praelongis, valde lamellatis ; lateralibus longis, lamel- 



latis subcurvisque ; margarita caeruleo-alba et iridescente. 



Shell winged, smooth, triangular, very much inflated, very inequilateral ; valves 



thin ; beaks elevated, swollen, epidermis yellowish, shining; cardinal teeth very long 



and very lamellar ; lateral teeth long, lamellar and slightly curved ; nacre bluish 



white and iridescent. 



Proc. Acad. Nat. Sci. Vol. 8, p. 93. 



iZa6.— Siam. S. R. House, M. D. 



My cabinet and cabinet of W. A. Haines, New York. 

 Diam. 1-9, Length 2-4, Breadth 3-2 inches. 



Shell winged, smooth, triangular, very much inflated, very inequilateral ; substance 

 of the shell thin, thinner behind ; beaks elevated, very much inflated and undulate 

 at the tip, in a double row with small striae on each side ; ligament rather long and 

 thin ; epidermis yellowish, inclined to olive, shining, with three obscure rays on the 



