158 Kansas Academy of Science. 



2. Cosmarium. 



Keu to Species. 



I. Single chloroplast (with one pyrenoid) in semi-cell. 



A. End view without central inflations, cytioderm punctate, mar- 

 gins granulate, semi-cell semi-obicular, diam. 12-16 mic, C. leve. 

 II. Two chloroplasts (with two pyrenoids) in each semi-cell. 



A. Membrane smooth or lightly punctate. End view with central 

 inflations, margins smooth, sinus acute inwardly, diameter 

 12-30 mic C. tithophorum. 



B. Membrane verrucose, rarely heavy punctate. 



1. End of semi-cells broadly rounded, diam. 60-68 mic. 



C. perforatum. 



2. End of semi-cells truncate, diam. 35-62 mic....C. Botrytis. 



U5. C. leve Rabenh. 



Kansas: Douglass, 1916. 

 Iowa (4). 



46. C. tithophorum Nordst. 

 Kansas: Douglass, August, 1915. 



47. C. perforatum Lund. 



Kansas: Douglass, August, 1915. 

 Jf8. C. Botrytis (Bory) Menegh. Plate III, fig. 15. 



Kansas: Horton, June, 1916, October, 1916; Parsons, 



August, 1915; Jewell City, 1915; Lyiidon, November, 



1915; Coffeyville, July, 1916; Burlingame, October, 



1916. 

 Colorado (15) ; Iowa (4) ; Nebraska (25) ; Missouri 



(11). 



Family II. ZYGNEMACEiE. 



Key to the genera of Zygiiemacem. 



I. Chromatophores one or two, star-shaped 1. Zygnema. 



II. Chromatophores one or more, parietal, more or less spiral. 



2. Spirogyrn. 



1. Zygnema. 



A9. Z. sp.1 



Kansas: Horton, June, 1916. 



2. Spirogyra. 



Key to Si)ecies. 



I. Septa between cells smooth, not folded back or replicate. 



A. Fruiting cells little or not at all swollen. 



1. One chromatophore in each cell. 



a. Zygospore broad ovoid, 1.5-2.5 times as long as wide, 

 diam. 18-20 mic S longata. 



b. Zygospore ellipsoid, 2-3 times as long as wide, diam. 19- 

 23 mic S. communis. 



2. Two or more chromatophores in each cell. 



a. Zygospore ovoid or globose, vegetative filaments 33-40 

 mic. in diam., cells 2-4 times as long as wide. 



S. decimina. 



b. Zygospore compressed ovoid, 140-160 mic. in diam., vege- 

 tative filaments, 150-160 mic. in diam <S. crassa. 



B. Fruiting cells distinctly swollen, one chromatophore in each cell, 

 end walls replicate, filaments 24-33 mic. in diam., zygospore 

 ellipsoid, 40-48 mic. in diam S. quadrata. 



