18 DESCRIPTION OF FIFTY-TWO SPECIES OF UNIONIDJi]. 



Shell very much tuberculate, quadrate, compressed, subequilateral, rounded 

 before, truncate behind ; valves rather thick, thicker before ; beaks rather promi- 

 nent ; epidermis saffron-yellow, without rays ; cardinal teeth rather large, com- 

 pressed and crenulate; lateral teeth short, oblique and lamellar; nacre salmon color 

 and elegantly iridescent. 



Proc. Acad. Nat. Sci., 1871, p. 190. 



Hab. — Cahaba Eiver, Shelby Co., Ala., E. E. Schowalter, M.D. 



My cabinet, and cabinet of E. E. Schowalter, M.D, 

 Diam. -8, Length 1-5, Breadth 1-8 inch. 



Shell tuberculate nearly over the whole disk, quadrate, subequilateral, round 

 before and truncate behind ; substance of the shell rather thick, much thicker 

 before; beaks somewhat prominent; ligament short, rather dark; epidermis saifron- 

 yellow, without rays, with distant lines of growth ; umbonial slope flattish ; pos- 

 terior slope compressed, carinate, with many small tubercles ; cardinal teeth rather 

 large, compressed, crenulate, double in the left and treble in the right valve ; late- 

 ral teeth short, oblique, lamellar and straight; anterior cicatrices distinct and well 

 impressed ; posterior cicatrices distinct and slightly impressed ; dorsal cicatrices 

 placed within the cavity of the beaks ; cavity of the beaks deep and angular ; 

 cavity of the shell shallow and wide ; nacre salmon color, splendent and satinlike, 

 deeper colored on the margin. 



Remarks. — Two specimens only were sent by Dr. Schowalter. The larger 

 appears to be full grown; the smaller rather more than half mature. The beautiful 

 salmon color and satinlike nacre of these specimens are very remarkable, the color 

 extending from the margin into the cavity of the beaks. It belongs to the quad- 

 rate nodulous group which contains lachrymosus, pustulatus, Schoolcraftii, &c., the 

 outline and compressed form being nearly the same with the latter. It differs 

 entirely in having very numerous tubercles over three-fourths of the disk, the 

 anterior fourth being somewhat welted. It is devoid of the broad green ray which 

 is usually so well defined in Schoolcraftii, no appearance of rays being in the two 

 specimens before me. The very remarkably fine nacre displays a series of irregular 

 undulations, caused by the exterior tubercles. The beaks of both specimens being 

 eroded, present no undulations. 



Unio simulans. pi. 5, fig. 15. 



Testa Isevi, obliqua, subcompressa, insequilaterali, antice rotundata, postice obtuse angulata ; valvulis 

 crassiusculis, antice erassioribus ; natibus prominentibus ; epidermide tenebroso-fusca, eradiata ; 

 dentibus cardinalibus parvis, compressis crenulatisque; lateralibus sublongis, curvis lamellatisque ; 

 margarita alba et iridescente. 



