Semi-Centennial Volume. 163 



II. Lobes of marginal cell imarginate, bidentate or bifid, disc con- 

 tinuous P. tetras. 



flO. P. duplex Meyen; (P. pertusum) Wolle. Plate III, 

 fig:. 26. 



Kansas: Douglas, August, 1915; Mound City, August, 

 1915; Yates Center, August, 1915; Coffeyville, July, 

 1916. 

 Missouri (11); Colorado (15). 



81. P tetras (Ehrbg.) Rolfs; {P. Ehrenhergii) A. Braun. 

 Kansas: Burlingame, October, 1916. 



Iowa (4); Missouri (11); Colorado (15). 



Order IV. ULOTRICHALES. 

 Key to the Fainilies of Ulotrichales. 

 I. Chromatophore net-, disk-, or band-shaped. 



A. Fronds unbranched filaments; sexual reproduction by isogamous 

 gametes '. Ulotrichcbceae. 



B. Fronds branched or simple. 



* Sexual reproduction by oogonia and antheridisi; chromato- 

 phores net-shaped; filaments erect (Edogoniaceae. 



* * Sexual reproduction by isogamous zoogametes; fronds fila- 



mentous usually with hairs Chsetophoraceae. 



Family I. Ultrichace^. 



Key to the genera of Ulotrichaceas. 



A. Filaments monosiphonous throughout, cells forming a cylindrical 

 filament. 



* Cells without pyrenoid, chromatophore a granular sheath 

 covering the wall more or less completely 1. Microspores. 



* * Cells with one or more pyrenoids, chromatophore a zonate 



band sometimes incomplete 2. Ulothrix. 



1. Microspora. 



82. M. stagnarum Kuetz. Lagerheim. 



Kansas: Olathe, August, 1915, November, 1915, April, 

 1916, in masises along with Microthamiutn Kuetz- 

 ingianiirn, July, 1916. 



Iowa (4). Missouri (11). 



2. Ulothrix. 



83. U. tenerrima Kuetz. 



Kansas: Washington, April, 1916, mixed with Con- 

 ferva minor. 

 Iowa (4); Colorado (15); Nebraska (3). 



Family II. CEdogoniace^. 



CEdogonium was the only genus of the CEdogoniaceae found. 



8If. Oe. irregnlare Wittrock. Plate IV, fig. 30. 



Kansas: Douglass, June, 1916, great fruiting masses. 



85. Oe. sp.? 



Kansas: Leavenworth, July, 1916. 



86. Oe. .fp.? 



Kansas: Jewell City, November, 1915, August, 1915, 

 October, 1916. 



87. Oe. up.? 



Kansas: Medicine Lodge, August, 1915. 



