DESCRIPTION OF FIFTY-TWO SPECIES OP UNIONIDiE. 19 



Shell smooth, oblique, somewhat compressed, inequilateral, rounded before and 

 obtusely angular behind ; valves rather thick, thicker before ; beaks a little promi- 

 nent ; epidermis dark brown without rays ; cardinal teeth small, compressed, and 

 crenulate ; lateral teeth somewhat long, curved and lamellar ; nacre white and 



iridescent. 



Proc. Acad. Nat. Sci., ISU, p. 190. 



Hah. — Cahaba River, Shelby Co., Ala., E. E,. Schowalter, M.D. 



My cabinet, and cabinet of Dr. Schowalter. 

 Diam. -6, Length 1, Breadth 1-5 inch. 



Shell smooth, oblique, somewhat compressed, inequilateral, rounded before, 

 obtusely angular behind; substance of the shell somewhat thick, somewhat thicker 

 before; beaks a little prominent; ligament short and dark brown; epidermis dark 

 brown, nearly black, without rays and with rather distant marks of growth ; um- 

 bonial slope rounded; posterior slope narrow elliptical, with two indistinct rays on 

 each valve, scarcely carinate ; cardinal teeth small, compressed and crenulate ; 

 lateral teeth rather long, curved and lamellar ; anterior cicatrices distinct, rather 

 small, deeply impressed; posterior cicatrices confluent and slightly impressed; 

 dorsal cicatrices placed over the centre of the cavity of the beaks ; cavity of the 

 shell rather shallow and wide ; cavity of the beaks somewhat deep and obtusely 

 angular ; nacre white and iridescent behind. 



Remarks. — Four specimens of this species were sent to me by Dr. Schowalter. 

 They seem all to be males. The species seems to be more nearly allied to TJ. 

 Genthii (nobis) than any other I am acquainted with. It differs in being more com- 

 pressed, and in being a little more oblique. When young the color of the epidermis 

 is no doubt a dark green. The most perfect specimen shows a disposition to exhi- 

 bit that color. None of the specimens had beaks perfect enough to show undula- 

 tions at the tips, which no doubt they possess when young. 



Unio dispansus. pi. 6, fig. 16. 



Testa laevi, elliptica, subinflata, valde inffiquila.terali, antice rotunda, postice obtuse angulata; valvulis 

 crassiusculis, antice crassioribus ; natibus prominulis, fere terminalibus ; epidermide tenebroso- 

 olivacea, perradiata; dentibus cardlnalibus parviusculis tuberculatis et in utroque valvule duplici- 

 bus ; lateralibus prolongis, lamellatis subrectisque ; margarita purpurea et valde iridescente. 



Shell smooth, elliptical, somewhat inflated, very inequilateral, round before and 

 obtusely angular behind; valves somewhat thick, thicker before; beaks a little 

 prominent, nearly terminal; epidermis dark olive, very much rayed; cardinal teeth 

 rather small, tuberculate and double in both valves ; lateral teeth very long, lamel- 

 lar and nearly straight ; nacre purple and very iridescent. 



