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



Oe. cardiacum, Hass. 



Oe. earbonicum, Wittr. 



Oe. Pringsheiinii, Cram. 



Oe. punctato-striatum, I). B>/. 



2. Oospore-s ellipsoid or oval. 



Oe. Boscii, Led. 



Oe. Landsborouglii, Hass. 



Oe. rivulare, Led. 



SECTION III. ORGANS OF FRUCTIFICATION IM- 

 PERFECTLY KNOWN. 



a. Oospores globose or subglobose. 



Oe. delicatuluni, Kg. 

 Oe. moiiiliforme, Wittr. 

 Oe. Fonticola, A. Br. 

 Oe. princeps, Hass. 

 Oe. Loiidiense, Wittr. 

 Oe. vesicatnin, Lynyb. 

 Oe. hexagonum, Hass. 



b. Oospores ellipsoid or oval. 



Oe. giganteum, Kg. 

 Oe. grande, Kg. 

 Oe. pyriforine, Wittr. 

 Oe. longatum, Kg. 



SECTION I. MONCECIOUS SPECIES. 



A. Oogonia always destitute of median processes. 

 a. Oospores globose or subglobose. 



OEDOGONIUM CRYPTOPORUM, Wittr. 



Oogonia single, elliptic, or somewhat depressed globose, 

 opening by a median pore, almost filling the oogonium, 

 sperrnogonia 2-7 celled, scattered. 



Diameter veg. cells, 7-9 // ; 4-6 times as long. 

 Diameter oogonia, 24-25 ju by 26-27 jn. 

 Diameter oospore, 22-23 /< by 19-21 /*. 

 Diameter sperm, cells, 6-8 /< by 7-9 //. 



Var. VULG-ARE, Wittr. 



Oogonia 2-5 continuous, or single ; spermogonia siibepi- 

 gynons or snbhypogynons or scattered. Measures all some- 

 what less than the typical form, and much more frequent. 



Ponds, Pennsylvania and New Jersey. 

 Plate LXXI V, figs. 1, 2, 



