SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 



241 



A CONTRIBUTION 



HISTORY OF THE FRESH-WATER ALGiE 



Of 



NORTH AMERICA. 



BT 



HORATIO 0. WOOD, Jr., M.D., 



rROFESSOU OF BOTANY, AND CLINICAL LBCTUREn ON DISEASES OF THE NERVOUS SVSTEW IN TBE 

 UNIVERSITY OF PENNSYLVANIA i PHYSICIAN TO THE PHILADELPHIA HOSPITAL, ETC. 



[accepted for 'PDBLICATIOH, PEBKCABT, 1872.] 



