SPIROGYRA 155 



matophore; conjugation scalariform; tubes formed by both gametangia; 

 fertile cells shortened and inflated to 34-39^1; zygospores ellipsoid, 

 24-31 ju, X 45-55/^; median spore wall yellow-brown, smooth. (PL XXII, 



Fig- 4-) 



Finland; China, Szechwan; South Africa. 



Distinguished from S. parvula by the much smaller vegetative cells; and 

 from S. pratensis by the absence of cells with 2 chromatophores, and by the 

 absence of globosely inflated sterile cells. 



17. Spirogyra parvula (Transeau) Czurda 1932. Siisswasserflora 



Mitteleuropa. 9, p. 170, Fig. 174. 



Vegetative cells 20-24 /x x 50-105^1, with plane end walls; i chro- 

 matophore, making i to 6 turns; conjugation mostly lateral, sometimes 

 scalariform; tubes formed by both gametangia; fertile cells inflated up 

 to 37 /x, often separating from one another but held in place by the male 

 filament; zygospores ellipsoid, 20-27 /x ^ 40-60 a^; median spore wall 

 yellow-brown, smooth; aplanospores similar in size and shape to zygo- 

 spores. (PI. XXII, Figs. 5-6.) 



United States: Iowa and Texas, to New York. 



Norway; India; China. 



18. Spirogyra gibberosa Jao 1935. Sinensia. 6, p. 586, PI. 4, Figs. 



50-51. 



Vegetative cells 19-21^1 x ^^-10^^, with plane end wall; i chro- 

 matophore, making 2 to 8 turns in the cell; conjugation scalariform, 

 sometimes lateral; tubes formed by the male gametangia; fertile cells 

 inflated on the conjugating side, to 45 /i, often separating from each 

 other as the spores mature; zygospores ellipsoid with more or less 

 pointed ends, 22-29 /a x 38-50 /x; median spore wall smooth, yellow at 

 maturity. (PI. XXII, Figs. lo-ii.) 



China, Szechwan. 



Separation of the sporiferous cells after conjugation is similar to that 

 frequently seen in S. parvula. Placed here because of doubt that tubes are 

 formed by the male gametangia. This may be only apparent, because of 

 subsequent enlargement of the receptive gametangia. 



19. Spirogyra borgeana Transeau 1915. Ohio Jour. Set. 16, p. 23. 

 Vegetative cells 30-35 ju- x 50-200 /x; with plane end walls; i chro- 



matophore, making 1.5 to 5 turns; conjugation scalariform; tubes 

 formed by both gametangia; fertile cells inflated on the outer side, 

 cylindric on the conjugating side; zygospores ellipsoid, 30-40 /it x 54-70 ;ix; 

 median spore wall yellow, smooth. (PI. XXII, Fig. 8; PI. XXIII, 

 Fig. 16.) 



United States: Iowa; Illinois; Michigan; Indiana; Ohio. 



