198 DESCRIPTION OF 



a young U. perdiz (nobis.) The nacre is very pearly and very thin, leaving a 

 broader margin than usual. Three specimens out of four before me have in- 

 terrupted rays indistinctly painted on the posterior part of the shell. 



Unio strigosus. Plate 9, Fig. 9. 



Testa transversa, compressd, valde incequilaterali, postice biangulatd; valvulis subtenuibus; natibua 

 subprominentibus, compressis; epidermide tenebroso-fuscd ; dentibus cardinalibus parvulis ; lateralibus 

 longis subrectisque ; margarita purpurea el iridescente. 



Shell wide, compressed, very inequilateral, biangular behind; valves rather thin; beaks somewhat pro- 

 minent, compressed ; epidermis dark brown ; cardinal teeth very small ; lateral teeth long and nearly straight ; 

 nacre purple and iridescent. 



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



My Cabinet. 

 Diam. .5, Length .1, Breadth 2.2 inches. 



Shell wide, compressed, very inequilateral, biangular behind; substance of 

 the shell rather thin; beaks somewhat prominent, compressed; ligament long 

 and thin; epidermis dark brown; cardinal teeth very small and lobed; lateral 

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

 confluent; dorsal cicatrices placed on the plate over the cavity of the beaks; 

 cavity of the shell very shallow; cavity of the beaks scarcely perceptible; nacre 

 purple and iridescent. 



Remarks. — This species belongs properly to the group of which the U. com- 

 planatus, Soland, is the type. In outline it resembles U. angustatus (nobis,) but 

 is a more compressed species. Two individuals only were received, one of 

 which is nearly white in the nacre. The cardinal teeth are remarkably small, 

 and, in the oldest specimen, stand nearly in the direction of the lateral teeth. 



Unio tener. Plate 10, Fig. 10. 



Testa ellipticd, valde compressd, valdh inaquilaterali; valvulis tenuihus; natibus subprominentibus; 

 epidermide luteo-fuscd; dentibus cardinalibus parvis; lateralibus longis subcurvisque ; margaritd alba 

 et iridescente. 



