ROBERT T, JACKSON. 



UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



FRESH-WATER 



RHIZOPODS 



NORTH AMERICA. 



BY 



JOSEPH LEIDY, M. D., 



PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA, AND OF NATURAL 

 niSTORY IX SWAETHMORE COLLEGE, PENNSYLVANIA. 



WASHINGTON: 



GOVERNMENT PRINTING OFFICE. 

 1879. 



