150 ZYGNEMATACEAE 



186. With 6 to 8 chromatopliores in 



each cell, spores ellipsoid 85. 5. wrightiana 



186. With 5 chromatophores in each 



cell, spores lenticular \(£. S. azygospora 



Aplanospores have been found together with zygospores in some 

 collections of the following species: S. catenae form is, S. denticiilata, 

 S. farlowii, S. gratiana, S. groenlandica, S. hyalina, S. inflata, S. juer- 

 gensii, S. rnajuscula, S. neglecta, S. obovata, S. parvula, S. pratensis, 

 S. protecta, S. quadrata, S. qiiinquelatninata, S. reftexa, S. sahnii, 

 S. semiornata, S. spreeiana, S. sitbpapidata, S. tenuissima, S. tjibodensis, 

 S. varians, S. weberi. 



Descriptions of Species 



SPECIES WITH PLANE END WALLS 

 USUALLY ONE CHROMATOPHORE 



1. SpmoGYRA COMMUNIS (Hassall) Kiitzing 1849. Species Al- 



garum, p. 439. Hassall. 1844. History of British Fresh- 

 water Algae, p. 148, PI. 28, Figs. 5-6. 



Vegetative cells i8-26iu, x ^5-90 m with plane end walls; i chro- 

 matophore, making 1.5 to 4 turns; conjugation scalariform and lateral; 

 tubes formed by both gametangia; fertile cells cyUndric, rarely enlarged; 

 zygospores ellipsoid, 19-26 m x 36-78 /a; median spore wall yellow, 

 smooth. (PI. XXI, Fig. i.) 



United States: Colorado to Texas; east to Massachusetts and New 

 Jersey. 



Reported from all the continents, also New Caledonia. 



Distinguished from other species with similar vegetative cells and with 

 approximately the same dimensions by the smooth ellipsoid spores, the 

 cylindric fertile cells, and the absence of inflated sterile cells. Found hybrid- 

 izing with S. varians at Charleston, Illinois. The resulting segregates were 

 also present. 



2. Spirogyra intorta Jao 1935. Sinensia. 6, p. 590, PI. 5, Fig. 58. 

 Vegetative cells 25-29 /j. x 60-1 83 /x, with plane end walls; filaments 



generally curved to spiral; i chromatophore, making 3.5-6 turns in the 

 cell; conjugation scalariform and lateral; tubes formed by both gam- 

 etangia; fertile cells cylindric, sometimes slightly enlarged; zygospores 

 ellipsoid, with pointed ends, 22-29/i x 4i-68;ti; median spore wall 

 yellow, smooth. (PI. XXI, Fig. 2.) 



United States: Texas, Johnson City, April 24, 1938 (Taft Coll.). 



China, Szechwan. 



