SPIROGYRA 



193 



by both gametangia; fertile cells cylindric; zygospores lenticular to 

 compressed-ovoid, 102-126 i-t x 140-154 /a x 72-97 a^; median spore wall 

 brown, smooth. (PL XXXII, Fig. 5.) 

 Russia, Bessarabia. 



166. Spirocyra azygospora Singh 1938. Jour. Indian Bot. Soc. 

 17, p. 372. 



Vegetative cells 85-90 a^ x 270-300^1, with plane end walls; chro- 

 matophores 5; conjugation unknown; reproduction by aplanospores 

 which are compressed-globose, 71-77/^ x 60-67 /x; rnedian wall thick, 

 brown, and smooth. (PL XLI, Fig. 16.) 



India, Gorakhpur, U.P., October, 1936. 



Fig. F. — Vegetative cell of Spirogyra crassa. The average length is usually about the 

 same as the diameter, and conjugating filaments always have some cells about one-half 

 the diameter. This cell has 8 chromatophores. 



167. Spirogyra crassa Kiitzing 1843. Phycologia Generalis, p. 280, 

 PL 14, Fig. 4. 



Vegetative cells 140-165 /x x 126-330 /a, with plane end walls; 6-12 

 chromatophores, making .5 to i turn; conjugation scalariform; tubes 

 zygospores compressed-ovoid, 120-150 /x x 140-160 a<. x 8o-ioom; median 

 spore wall brown, with irregular shallow pits. (PL XXXII, Fig. 6.) 



United States: Generally distributed, but not common, from Minne- 

 sota and Wisconsin to Louisiana and the eastern seaboard. 



Europe; Australia; South Africa. 



Collections of what appear to be vegetative filaments of this species in 

 shaded ponds are not infrequent, but fruiting specimens are relatively rare. 



