156 ZYGNEMATACEAE 



Czechoslovakia; Tibet; China. 



Figure 16 on Plate XXII I depicts an instance in which the terminal 

 cells of 2 adjacent filaments conjugated through the end walls with 2 adjoin- 

 ing receptive gametangia of a third filament. The specimen was collected 

 near Douglas Lake, Michigan. Named for the late Oskar F. A. Borge of 

 Stockholm, Sweden. 



20. Spirogyra calcarea Transeau 1934. Trans. Amer. Micros. 



Soc. 53, p. 226. 



Vegetative cells 37-42 /x x 40-120/j., with plane end walls; i chro- 

 matophore, making 2 to 5 turns in the cell; conjugation scalariform; 

 tubes formed by both gametangia; receptive gametangium inHated only 

 on the outer side; zygospores ellipsoid, 40-55 /a x 58-80 /a; median spore 

 wall smooth, yellow. 



United States: Alabama, Birmingham, sinkholes in limestone. 



Similar in form to S. borgeana but larger in all dimensions. 



21. Spirogyra bullata Jao 1935. Sinensia. 6, p. 588, PI. 4, Fig. 55. 

 Vegetative cells 19-22/x x 41-83;", with plane end walls; i chro- 



matophore, making 1.5-5.5 turns in the cell; conjugation scalariform; 

 tubes formed by both gametangia; sterile cells buUate up to 64 m in 

 diameter and occurring in rows up to 25 cells long; fertile cells cylindric 

 or slightly enlarged; zygospores ellipsoid, 22-291". x 31-35 (-51)^; spore 

 wall smooth, yellow at maturity. (PI. XXII, Fig. 13.) 



China, Szechwan. 



Differs from S. pratensis in the shorter spores and absence of inflated 

 fertile cells. 



22. Spirogyra pratensis Transeau 1914. Amer. Jour. Bot. 1, 



p. 292. 



Vegetative cells 17-20 /a x 80-240 jU, with plane end walls; i chro- 

 matophore (rarely 2), making i to 8 turns; reproducing commonly by 

 both zygospores and aplanospores; conjugation scalariform and lateral; 

 tubes formed by both gametangia; fertile cells enlarged or fusiform- 

 inflated to 38 /ti; sterile cells cylindric or inflated up to 90 m in diameter; 

 spores in most cells ellipsoid, in others ovoid, or cylindric-ovoid, 

 2^-^6iJi X 50-70^1; median spore wall yellow, smooth. (PI. I, Fig. 7; 

 PI. XXII, Figs. 14-18.) 



United States: Iowa; Wisconsin; Arkansas; Illinois; Michigan; Ken- 

 tucky; Ohio. 



China, Peiping (Jao Coll.), Nanking (Li Coll.). 



The occurrence of globoscly swollen sterile cells and the presence of 

 lateral and scalariform conjugation together with aplanospore formation in 

 most collections and sometimes in a single pair of filaments give character 

 to this species. 



