34 DESCRIPTIONS OF 



in the right valve, the interior division passing under the suiierior one ; lateral teeth 

 rather long, lamellar, nearly straight, single in the right and double in the left valve ; 

 anterior cicatrices confluent ; posterior cicatrices confluent ; dorsal cicatrices placed 

 within the cavity of the beaks and on the under side of the cardinal tooth ; pallial 

 cicatrix slightly impressed ; cavity of the shell deep and rounded ; cavity of the beaks, 

 deep and subangular ; nacre white inclining to salmon and iridescent. 



Bemarhs. — Among the shells from Takrong Eiver, was a single small Unio which 

 has the appearance of being nearly, if not quite mature. It has that character of the 

 cardinal teeth, being single and double on the reversed sides, so common with the 

 species from the East of Asia. The tips of the beaks being eroded, the character of the 

 undulations cannot be given, but it is evident from those which may be yet seen on 

 the posterior slope of this specimen, that they must be numerous, regular and close. 

 In outline and in color it is near to U. crocatus, (nobis,) from Georgia ; but is a much 

 smaller species and rather more transverse. 



Unio Coloradoensis. PI. 31, fig. 29. 



Testfi lajvi, elliptica, inflatil, valde inaequilaterali ; valvulis erassis ; natibus clevatis magnisque ; epidermide 

 luteo-castanea, obscure radiatil et polita ; dentibus cardinalibus magnis, duplicibus, acuminatis crenu- 

 latisque ; lateralibus magnis, prrelongis, lamellatis subcurvisquo ; margarita purpurea et iridescente. 



Shell smooth, elliptical, inflated, very inequilateral ; valves thick ; beaks elevated 

 and large ; epidermis yellowish chestnut, faintly rayed and polished ; cardinal teeth 

 large, double, pointed and crenulate; lateral teeth large, very long, lamellar and 

 somewhat curved ; nacre purple and iridescent. 

 Proc. Acad. Nat. Sci. Vol. 8, p. 103. 



Hah.—R\o Colorado, Texas. B. W. Budd, M. D. 

 My cabinet and cabinet of Dr. Budd. 

 Diam. 1-8, Length 3-1, Breadth 4-9 inches. 



Shell smooth, elliptical, inflated, very inequilateral, subbiangular behind ; substance 

 of the shell thick, thinner behind ; beaks elevated and large ; epidermis yellowish 

 chestnut, faintly and closely rayed and polished on the umbones ; ligament large, long 

 and thick ; umbonial slope rounded and inflated ; posterior slope raised into a carina ; 

 cardinal teeth very large, double in both valves, pointed and crenulate ; lateral teeth 

 single in the right and double in the left valve, very large, lamellar and somewhat 

 curved ; antei'ior cicatrices distinct, the inferior large and deeply impressed ; posterior 

 cicatrices confluent, large ; dorsal cicatrices numerous, deeply impressed and crossing 

 the cavity of the beak; pallial cicatrix large and deeply impressed ; cavity of the 

 shell large ; cavity of the beaks large and rounded ; nacre purple and very iridescent. 



Bemai-Jcs. — Dr. Budd, to whose kindness I owe the possession of this shell, has a 

 second specimen, and these are the only two I have seen. It is nearly allied to 

 l^nrpurain-'i, Jjam., on one side, and to nJafits, Say, on the other; it is less inflated 



