NEW FRESH WATER AND LAND SHELLS. 201 



B-emarks. — A single specimen only of this species was taken by Mr. Edgar. 

 It perhaps most nearly resembles U. Medelli7ms (nobis,) and U. radiatus. It is 

 smaller and more transverse than the latter. Its pearly lustre is unusually fine. 

 — In the individual before me the rays are thick and large. 



Unio obtusus. Plate 11, Fig. 13. 



Testa ohovatd, inflata, postice rotundatd; valvulis subcrassis ; natibus subprominentihus ; epidermide 

 luted, nitida; dentibus cardinalibus subgrandibus ; later alibus longis subrectisque; margaritd alba et 

 iridescente. 



Shell obovate, inflated, rounded behind ; valves rather thick ; beaks rather prominent ; epidermis yellow, 

 shining; cardinal teeth rather large; lateral teeth long and nearly straight; nacre white and iridescent. 



Hab. Chattahoochee River, Columbus, Georgia. Dr. Boykin. 



My Cabinet. 

 Diam. .9, Length 1.3, Breadth 2.2 inches. 



Shell obovate, inflated, rounded behind; substance of the shell rather thick; 

 beaks rather prominent; ligament rather short and thin; epidermis smooth, 

 shining, yellow over the whole disk except on the posterior slope, which is dark 

 brown; cardinal teeth rather large, double in both valves, erect, pointed; late- 

 ral teeth long and nearly straight; anterior cicatrices distinct; posterior cicatrices 

 confluent; dorsal cicatrices on the plate near to the cardinal tooth; cavity of 

 the shell deep and rounded; cavity of the beaks rather deep and angular; nacre 

 white and beautifully iridescent. 



Remarks. — Three specimens of this species now under my examination dif- 

 fer but little from each other. The nacre of one on the posterior part is golden 

 and very rich. This specimen has an indistinct ray upon it, the others are 

 ray less, having a rich yellow surface. It has some resemblance to U. cariosus, 

 Say, but is a more transverse shell, and differs in having the posterior slope 

 entirely dark, while the cariosus is usually rayed on this part. 



Unio fatuus. Plate 11, Fig-. 14. 



Testa transversd, compressd, emarginatd; valvulis subcrassis ; natibus parvis ; epidermide subviridi, 

 radiatd; dentibus cardinalibus parvis ; lateralibus longis, subcurvisque ; margaritd albd et iridescente. 



