68 FRESH-WATER ALG.E OF THE UNITED STATES. 



The following are the species of the United States as far as 

 identified, arranged in accord with the plan of Wittrock's 

 monograph. 



(EDOGONIUM. 



SECTION I. MONCECTOUS SPECIES. 

 OOGrONIA ALWAYS DESTITUTE OF MEDIAN PROCESSES. 



A. Oospores globose or subglobose. 

 a. Oogonia globose or subglobose. 



Oe. crytoporum, Wittr. 

 Oe. obsoletum, Wittr. 

 Oe. fragile, Wittr. 

 Oe. zig-zag, Cleve. 

 Oe. vernale, Has*. 

 Oe. crispum, Hats*. 

 Oe. plusiosporum, Wittr. 

 Oe. polymorphuin, Wittr. 

 Oe. autumnale, Wittr. 



b. Oogonia elliptic or egg-shaped. 

 Oe. urbicum, Wittr. 



B. Oospores elliptic or egg-shaped. 



Oe. paludosuni, Hays. 

 Oe. crassum, Hass. 

 Oe. gracillimum, Wittr. 



SECTION II. DICECIOUS SPECIES. 



SUBSECTION I. WITH DWARF MALES. 



A. Species with dwarf males unicellular. 



a. Oogonia furnished with vertical intersections. 

 Oe. platygynum. 



b, Oogonia destitute of vertical intersections. 



1. Oospores globose or subglobose. 



Oe. decipiens, Wittr. 

 Oe. Areschougii, Wittr. 

 Oe. undulatum, A. Br. 

 Oe. cateractum, Wolle. 



Oospores subellipsoid. 

 Oe. cyathigerurn, Wittr, 



