UNITED STATES GEOLOGICAL SUEVEY OF THE TEERITOEIES. 



FRESH-WATER 



RHIZOPODS 



NORTH AMERICA. 



BY 



JOSEPH l.EIDY, M. D., 



tROFKSSOR OF ANATOMY IN THE UNIVERSITY OP PENNSYLVANIA, AND OF NATURAL 

 HISTORY IN SWARTHMORE COLLEGE, PENNSYLVANIA. 



I M « » 



WASHIITGTON: 



GOVEENMENT PEIKTING OFFICE. 

 1879. 



