UNITED STATES GEOLOGICAL SURVEY OF THE TEIMUTOMES. 



FRESH-WATER 



RHIZOPODS 



or 



NORTH AMERICA. 



JOSEPH LEIDY, M. 13., 



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

 HISTORY IN SWARTHMORE COLLEGE, PENNSYLVANIA. 



"WASHINGTON: 



G-OVEKNMENT PRINTING OFFICE. 



1879. 



