s 



..-' 



Transactions of The Academy of Science of St. Louis. 



VOL.. vir. No. 1. 



'ip/' 



A STUDY OF THE UNIONID^ OF ARKANSAS, 

 WITH INCIDENTAL REFERENCE TO THEIR DIS- 

 TRIBUTION IN THE MISSISSIPPI VALLEY. 



By 



R. ELLSWORrH CALL. 



Issued January 3d^ 1896. 



